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WAN AOAOL CAN
HAA/18 1)
LIMNOLOGICAL ASPECTS
OF
WATER SUPPLY AND WASTE DISPOSAL
Publication of the American Association
for the Advancement of Science
Edited by
F. R. Movuuton
and
FLORENCE HITZEL
AL |
rom
SU
rat) AAAS {
WOODS HOLE, MASS.
W. Ee @: E
American Association for the Advancement of Science
1515 Massachusetts Avenue, N.W., Washington 5, D. C
1949
Copyright, 1949, by
Tue AmerRICAN ASSOCIATION FOR THE
ADVANCEMENT OF SCIENCE
PRINTED BY
THE HORN-SHAFER COMPANY
BALTIMORE 2, MD.
By THEODORE A. OLSON, Chairman of the Symposium
SCHOOL OF PUBLIC HEALTH, UNIVERSITY OF MINNESOTA, MINNEAPOLIS, MINN.
The present period is characterized by much specialization in scientific
work, often with resulting neglect of borderline fields of considerable im-
portance. This lack of inter-science cooperation is often apparent even
within relatively small subdivisions of scientific work. For instance, Stein-
haus (1946) in his “Insect Microbiology” stated that the microbiologist and
the entomologist greatly need an introduction to one another, although both
are in the generally accepted sense biologists.
It is at once apparent that the lack of complete understanding between
scientists in related fields may be even greater when one considers the border
area lying between the engineer and the biologist. Dr. Paul Sears of Oberlin
College, in discussing this matter (1947), suggested biology courses for
engineers and pointed out that there are many ill effects which are unwit-
tingly produced by engineers because they had too little knowledge of liv-
ing things and their ecology. An industrial engineer may, for example, do
an excellent job creating factories of great economic importance to the
country yet fail to solve properly the waste disposal problems associated
with the same industry. Thus valuable surface waters may be seriously
polluted to the point where great economic, as well as aesthetic, losses are
sustained. Problems of drainage and of irrigation often involve questions
relating to biological principles as well as to engineering skills.
Conversely, the biologist may often fail to take advantage of the knowl-
edge available in the field of engineering and of the sound advice he might
receive from members of that profession. Carried sufficiently far, a plan for
cooperation between the two groups, which necessitates working and think-
ing together, should lead to coordinated efforts which would be really effec-
tive and practical. Such action on the part of biologists and engineers
should break down the invisible wall which at present seems to exist between
their respective fields of endeavor.
In view of the general agreement that future progress must include
cooperation and mutual understanding in fields of inter-science, the appear-
ance of this volume is timely. The subject matter presented represents a
sampling of the border area which lies within the scope of interests common
to the engineer, the limnologist, and the oceanographer. On this common
ground a better understanding and a fuller appreciation of the role played
by each profession can be built. It is hoped, therefore, that these papers
will stimulate further thinking and cooperative work in the fields of activity
represented, and that ultimately they will lead to other as yet unexplored
areas of common interest.
THEODORE A. OLSON
Chairman of Symposium
REFERENCES CITED
Sears, P. B. 1947. Importance of ecology in the training of engineers. Science, 106: 1-3.
Stemnuavus, E. A. 1946. In Insect Microbiology. Comstock Publishing Co., Inc., Ithaca,
N.Y:
LIST OF CONTRIBUTORS
ALFRED F. BartscH, PH.D.
Biologist, Pacific Northwest River Basin Office, U. S. Public Health Service, Portland,
Ore.; formerly Senior Biologist, Wisconsin Committee on Water Pollution, State Board
of Health, Madison, Wis.
Marcaret P. Brices, M.A.
Graduate Student, Department of Agricultural Bacteriology, University of Wisconsin,
Madison, Wis.
CorneuiA L. Carty, PH.D.
Associate Professor of Botany, Barnard College, New York, N. Y.
Suin L. Cuane, M.D.
Assistant Professor of Sanitary Biology, Department of Sanitary Engineering, Graduate
School of Engineering and School of Public Health, Harvard University, Cambridge,
Mass.
WarrEN 8. CHURCHILL, M.A.
Biologist, Wisconsin Conservation Department, Northeast Fishery Area Headquarters,
Woodruff, Wis.
Bostwick H. Ketrcuum, PH.D.
Marine Microbiologist, Woods Hole Oceanographic Institution, Woods Hole, Mass.
JAMES B. Lacxry, PH.D.
Editor, The Blakiston Company, Philadelphia, Pa.
JoHN B. Moyte, PH.D. 7
Aquatic Biologist, Fisheries Research Unit, Minnesota Department of Conservation,
St. Paul, Minn.
THEODORE A. Ouson, A.M.
Associate Professor, School of Public Health, University of Minnesota, Minneapolis,
Minn.
CLARENCE FE). Tart, Pu.D.
Associate Professor of Botany, The Ohio State University, Columbus, Ohio.
Wiis M. Van Horn, Pu.D.
Research Associate, The Institute of Paper Chemistry, Appleton, Wis.
JoHn N. Witson, M.A.
Associate Public Health Biologist, Minnesota Department of Health, Minneapolis,
Minn.
TABLE OF CONTENTS
Microbiota of Sewage Treatment Plants and Polluted
SEDC al seee ORENDEING ) WILSON D Weyer ereemerarntia sae vshrce snes tare eyes ii 1
Some Epidemiological and Biological Problems in Water-Borne
ATMO MOIASISS 1) SERED I ©ETAN GME NC py ales acatelcuel aie teaches elec e creel 16
Biotic Responses to Stream Pollution During Artificial Stream
Reaeration. ALFreD F. BartscH AND WARREN S. CHURCHILL.... 33
A Study of Kraft Pulping Wastes in Relation to the Aquatic
Emyinonments., WaiLLisn Mia WANDIELORN 4552) le cei ee em cicie chee e 49
Plankton as Related to Nuisance Conditions in Surface Water.
ANAS UB ES IEA CAGE Yous i eure te mele neta Peas ier Deane Nast oye a Tera ve ah UE aS 56
Preliminary Studies on the Viability and Dispersal of Coliform Bacteria
in the Sea. Bostwick H. KercHum, Cornenia L. CarrEy, AND
IVIAR CARED RIGGS 0. -scscveper ne levcireee epee aot ne ary aT ent oat Lt ces dined sets 64
The Algologists’ Part in City and Industrial Water Supply Problems.
(STAR ION CE ARAB rete elec cto atat acerca a Ud UNE iy vale Mars uO iaoa bay au ante 74
The Use of Copper Sulphate for Algal Control and its Biological
hmplications ms JOHN d.) MOYaEn Varese wives eee le as a kia 79
;
Wis
uur
‘
Hy
MICROBIOTA OF SEWAGE TREATMENT PLANTS AND
POLLUTED STREAMS
By JOHN N. WILSON
MINNESOTA DEPARTMENT OF HEALTH, MINNEAPOLIS, MINN.
LATE LAsT century there was some controversy among sanitary engi-
neers in this country and in Europe concerning which of two methods of
sewage treatment should be advocated—chemical or biological treatment.
Those who favored the former tried to show that sewage could be treated
successfully in much the same manner as surface water is prepared for
drinking. However, the advocates of Mother Nature’s method—biological
treatment—had caught a preliminary glimpse of her seemingly miraculous
powers of self-purification and were pressing ahead rapidly with their ex-
periments in this virgin field. In 1890, a report from the Lawrence Experi-
ment Station, in Massachusetts, stated that when sewage is passed intermit-
tently through a filter of coarse gravel from which all sand has been washed,
“_. each stone was kept covered with a fine film of liquid, very slowly-
moving from stone to stone and continually in contact with air in the spaces
between the stones. The liquid, starting at the top as sewage, reached the
bottom within twenty-four hours with the organic matter nearly all burned
out” (Mills 1890). Shortly after this report an English investigator, Scott-
Moncrieff (Anonymous 1892), experimenting with the treatment of sewage
from his own home developed a filter plant using upward flow and demon-
strated beyond any doubt the biological action as opposed to mechanical
action alone. Although the early experiments in sewage treatment were con-
ducted largely by engineers, representatives of other professions, such as
bacteriologists, chemists, biochemists and biologists, began gradually to ap-
pear on the scene to contribute their share in the development of the methods
of biological treatment in use today.
The purpose of this paper is to discuss sewage Prentment from a biologi-
cal viewpoint and to show some relationships that exist between the micro-
biota of sewage treatment plants and polluted streams. The term microbiota
is used to designate those plants and animals which range from the higher
bacteria through certain aquatic msect larvae. In a sense, microbiota em-
bodies a synthesis of plankton (flowing sewage or polluted water of a
stream) and benthos (biological film of trickling filter or similar treatment
unit and bottom-dwelling organisms of a polluted stream). Only those or-
ganisms which can be identified by direct microscopic examination are
included. The large group of bacteria which is commonly identified by
culture methods is omitted.
To facilitate interpretation of the data, the microbiota of the sewage
treatment plants included in these studies have been divided into three
classes on the basis of function: The binding organisms, the free-living
1
2 LIMNOLOGY, WATER SUPPLY AND WASTE DISPOSAL
organisms, and the scouring or grazing organisms. The members of the
binding group comprise the fibrous-gelatinous matrix of the biological film.
The slime bacterium, Zoogloea ramigera, certain molds and fungi, and fila-
mentous algae are among the representatives of this group. The free-living
organisms include the higher bacteria, protozoans and rotifers. The rotifers
and larger protozoans feed upon bacteria and solids in the sewage. Many
smaller protozoans subsist largely upon dissolved nutriment in the sewage.
Those which feed upon bacteria help to prevent overpopulation among the
bacteria and some function as colloiders of dissolved material. The scour-
ing or grazing group includes insect larvae, round worms, annelid worms,
snails and adult insects (Collembola). As the name suggests, these organ-
isms feed directly upon the biological film and sewage solids. But scouring
organisms may sometimes create a nuisance or interfere with normal plant
operation; consequently, control measures have been developed in recent
years (Page 11). Nevertheless, they play an unquestioned role, particularly
in low-rate trickling filters,* by consuming solids in the sewage, by reducing
the volume of the film and by inducing sloughing, which opens the voids
between the rocks, thereby enhancing aeration.
The studies on the microbiota of sewage treatment plants have been
made intermittently over a period of five years. The following projects are
included:
1. Investigations on the biology of high-rate trickling filters were made
over a period of three months in 1942. The results of this work were pub-
lished as a supplement to the report of the engineering investigations of
filters of this kind (Walton 1943). This project was sponsored by five
State Health Departments: Wisconsin, Minnesota, Iowa, Illinois and
Indiana.
2. Studies on the biology of contact aerators (Hays Process) were made
during a brief period in the winter of 1944. This work was under the aus-
pices of the Repairs and Utilities Branch of the Seventh Service Command
in Omaha and was performed as a supplement to engineering investigations.
Five plants were included in the survey.
3. Investigations of the sewage treatment plant at South St. Paul,
which handles a large volume of wastes from meat packing plants, were
made this last summer (1947). The biological studies included the filter
back-washing operation and a vertical section of a filter.
Most of the reactions which take place in a sewage treatment plant may
also be observed to some extent in a polluted stream; therefore, let us first
consider stream self-purification from the microbiotic standpoint.
MIcROBIOTA OF STREAM SELF-PURIFICATION
In his book entitled “Stream Sanitation,” Professor E. B. Phelps (1944)
uses a financial simile in a most apt manner to describe the self-purification
* For the purpose of this paper, the following distinction is made between low-rate
and high-rate trickling filters: Low-rate trickling filters are operated with intermittent
application of sewage, whereas high-rate filters are dosed continuously. The total
amount of biochemical oxygen demand applied per unit period of time on a high-rate
filter is much higher than on a low-rate filter.
MICROBIOTA OF SEWAGE TREATMENT PLANTS IN STREAMS 3
of streams. Mother Nature is a banker, the amount and strength of the
sewage discharged to the stream are the debt, or liability, and the dissolved
oxygen and other factors of self-purification are the assets. If the demand
for oxygen is excessive in relation to that available, the dissolved oxygen
is depleted and the stream goes into bankruptcy. At the opposite extreme,
the stream may be so large in comparison to the amount of waste discharged
into it that the sag in dissolved oxygen may be scarcely perceptible.
Let us consider a stream which has been polluted to a moderate degree
so that it could be classed somewhere between the two foregoing extremes.
Space will not permit a discussion of the physical, chemical and biochemical
factors of self-purification; however, it is within the province of this paper
to demonstrate the role of the microbiota of a stream in the amortization of
the pollution debt. Mother Nature is an exacting banker. She expects the
pollution debt to be paid off without any needless delay, but she is also re-
sourceful in changing the composition of the microbiotic association to cope
with the situation. The rigorous conditions of the environment caused by
dumping sewage into the stream are met at first by eliminating the sensitive
species from the microbiota. The increase in turbidity is a factor in limiting
the growth of phytoplankton, and the deposition of putrescible sludge makes
the bottom of the stream untenable for the growth of many insect larvae and
other sensitive benthic organisms. As a rule, the zooplankters dominate
the polluted stretches. These include the bacteria-feeding ciliate and flagel-
late protozoans as well as the saprophytic forms. Because of the greatly
augmented supply of food present in the stream below the point of sewage
discharge, the population of these organisms is usually large.
As the sewage solids settle to the bottom to form sludge deposits, the
normal association of benthic organisms changes from a large number of
genera and species to a few hardy genera whose numbers usually increase
prodigiously. For example, it is not unusual to observe aquatic annelids
(sludge worms) in such numbers on a slightly submerged sludge bank that
they resemble the nap of a thick rug. The importance of these biological
workmen and of other scavengers of the benthos in the process of self-puri-
fication of streams has been demonstrated repeatedly.
When recovery progresses to the point where there is some clearing
of the water, algae and chlorophyll-bearing protozoans may be seen to thrive
in the fertile water, sometimes to the extent of producing a water bloom.
The stream returns to its normal condition when the fertility decreases below
the point required for the maintenance of the algal bloom. At the same
time, hosts of bacteria, after consuming nutriment which is available to
them in the diluted sewage, starve and perish as they move down stream.
In this manner, a stream purifies itself.
Sewage treatment plants are often called “condensed streams’ where
self-purification is carried on by a succession of different organisms, each
utilizing the waste products of the preceding species. In such a system,
one should be able to trace out the various zones of self-purification, namely:
Recent pollution, active decomposition and recovery. While it is true that
the development of processes of biological treatment of sewage was aided by
4 LIMNOLOGY, WATER SUPPLY AND WASTE DISPOSAL
observations on the self-purification of polluted streams, yet, in the process
of contracting a stream to the dimensions of a sewage plant, forces other
than those normally active in the self-purification of a stream are brought
into play. Surface, contact, and interfacial forces become operative as a
group. For example, in a trickling filter, the sewage disperses a thin film
and passes from rock to rock with all substances in the sewage coming into
contact with the biological film. Particles in the sewage are adsorbed by
the film and digested particles are removed from the film to be washed out
with the effluent from the filter. The reduction in the strength of sewage
(biochemical oxygen demand removal) by biological contact processes at
work in a sewage plant approaches 90%. At normal summer temperatures,
this value is reached in the self-purification of polluted streams only after
days of flow. However, the usual time required for the percolation of
sewage through sand beds and trickling filters is 1-2 hours (Imhoff and
Fair 1940). In spite of this contrast in the rate at which self-purification
proceeds, many of the same organisms and many similar biotic relationships
may be observed in streams and sewage plants.
MicroBioTa OF SEWAGE TREATMENT PLANTS
Technique. Five series of samples were collected for the identifica-
tion and enumeration of the microbiota from the sewage treatment plant at
Owatonna, Minnesota, which was included in the cooperative survey of high-
rate filters (Walton 1943). These samples were taken from the upper sur-
face rock, one foot beneath the surface and the filter effluent. The samples
of effluent from the filter were taken during extensive sloughing or unload-
ing induced by stopping the distributor for a brief period. The rock medium
was analyzed on the basis of numbers of organisms per square cm of sur-
face area. The samples of effluent were enumerated on the basis of numbers
per liter of the original samples which were examined without concentration.
Quantitative determinations were made on samples preserved in formalin,
but in order to facilitate the identifications the living organisms were exam-
ined. The standard plankton counting cell (Sedgwick-Rafter) was used
with a maximum magnification of 210 diameters.
Samples from contact aerators were usually obtained by scraping
growth from plates and sample boards in the aerators. Wherever possible,
at each plant, one plate was lifted from near the influent to the primary
aerator, one from near the effluent, and two additional plates from corres-
ponding locations in the secondary aerators. This was done to determine the
nature of the biological gradient as postulated by the proponents of the
process. The samples were examined in the fresh state with the maximum
magnification of 440 diameters. The results were qualitative, but the rela-
tive numbers of each organism were recorded for comparative purposes.
The method of quantitative analysis of the filter growth in the plant at
South St. Paul differed from the technique described above. Instead of
measuring the surface of several rocks from which the growth had been
scraped, the volumes of representative samples of growth were measured
in a graduate cylinder and diluted to a sufficient degree to permit examina-
MICROBIOTA OF SEWAGE TREATMENT PLANTS IN STREAMS 5)
tion in a standard counting cell. By this means a direct relationship is
established between the quantity of growth and the number of organisms
present therein. The vertical series of samples from the filter rock were
collected at 6-inch intervals over a distance of 5 feet, where a filter had
been opened for repair. In order to determine the microbiotic composition
of the film and solids removed by backwashing a filter, samples were col-
lected near the beginning and near the end of the operation. Before the
backwashing started, however, a sample for control was collected from the
combined filter effluent as it emptied into the final clarifier.
REACTION OF MICROBIOTA TO CHANGES IN THE OPERATION OF A
TRICKLING FILTER
The sewage treatment plant at Owatonna, Minnesota, was investigated
5 times from March 18 to April 24, 1942, to determine the effects of changes
in plant operation upon the microbiota of the trickling filters. This sewage
plant was designed to handle a large volume of waste from a canning fac-
1,200,000
i ie cl
Binding Organisms
Started
Free Living Organisms
per square centimeter
Parallel! Flow
Numbers
Intermediate Clarifier Bypassed
Numbers per square centimeter
High Rate Dosage
———— Parallel Flow Started
409,
200.
Fic. 1. Effect of changes in the operation of the sewage plant at Owatonna, Minn.
upon the microbiota in the upper part of the second stage trickling filter.
Bo,
pO eee
#
Fo Intermediate Clarifier Bypassed
Apr. 24
Dotes—1942
tory in the fall in addition to the normal flow of sanitary sewage from the
community of nearly 9,000 population. Provision was made in the design
for coping with the wide variation in strength and volume of sewage. Among
other devices for absorbing “shock loads,” the design called for two trickling
filters placed in series with an intermediate clarifier between. The microbi-
ota in the secondary filter only will be discussed.
Analytical data obtained from earlier tests on this plant showed that
during the 9 months of the year when the cannery is inoperative, the primary
filter does most of the work and the secondary filter operates on a strictly
6 LIMNOLOGY, WATER SUPPLY AND WASTE DISPOSAL
rationed diet. The microbiota is partially “starved” during these slack
months. Just as a patient in a condition of physical weakness must be
strengthened before an operation, so it was considered advisable to enrich
the secondary filter before the experiments were conducted. Consequently,
the intermediate clarifier was bypassed and the effluent from the primary
filter flowed directly to the secondary filter. This procedure was started on
March 20 and continued 11 days (March 31), after which auxiliary piping
was installed to provide parallel operation of the two filters with low-rate
dosage. Three weeks later (April 17), the outer orifices of the distributors
were plugged as a means of increasing the rate of dosage on the central
portion of the filters. This schedule of operation is shown on the graphs
(Figs. 1,2). The samples which were collected on April 17 represented the
second series taken after parallel flow was begun and they immediately
preceded the change to high-rate dosage.
eT ean i
fic
3
u
ee
da
z rab
Free Living Orgenisms__
3
IN
Binding Organisms
eZ moet
7
ay
ne
Mar. 18
Numbers per Liter
Intermediate Clarifier Bypassed
Parallel Flow Started
Parallel Flow
Intermediate Clarifier Bypassed
High Rate awe
Apr. 24 jar. ar. 1. ts Apr. 24
Dates—1942
Fic. 2. Effect of changes in operation of the sewage plant at Owatonna upon the
microbiota in the effluent from the second stage trickling filter.
These changes of operation caused quantitative as well as qualitative
changes in the microbiota within the secondary filter, which is the one to be
discussed (Figs. and Tables I and II). The initial enrichment process caused
a noticeable increase both in binding and free-living organisms, but a
decrease in the scourers. Among the binding components of the film, the
white sulphur bacteria (Beggiato alba) almost doubled in numbers and
fungi appeared on the surface rock where they were not found before.
Almost all of the free-living organisms increased as a result of the more
adequate diet of bacteria and organic solids. Predominant among these were
two ciliate protozoans, Opercularia sp. and Paramecium sp., and rotifers.
Scouring or grazing organisms were not abundant at any time during the
tests. Those present were minute round worms and a few sludge worms
MICROBIOTA OF SEWAGE TREATMENT PLANTS IN STREAMS
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MICROBIOTA OF SEWAGE TREATMENT PLANTS IN STREAMS 9
(Oligochaeta). The change to parallel flow modified the volume and char-
acter of the sewage sprinkled on this filter. There was a 50% decrease in
volume of sewage but instead of receiving partially digested solids and
sloughed film from the primary filter, the filter received fresh material from
the primary sedimentation chamber. As a result, the binding organisms in-
creased in the upper section of the bed as well as in the effluent from the
filter; but the free-living organisms decreased steadily in the upper layer of
rock and increased in the lower strata toward the middle of April, as evi-
denced by the samples of filter effluent on April 17.
On April 17, when the rate of dosage was increased on the central
portion of the filter, there was a widespread unloading of the microbiota
indicated by the effluent, while at the same time the numbers of organ-
isms increased in the upper strata of rock. The last investigation (April 24,
1942) indicated that the filter had assumed the biological characteristics
of a typical high-rate unit, whose microbiota are described as follows:
1. The binding group composed of the omnipresent slime bacterium,
Zoogloea ramigera, large numbers of Beggiatoa alba (white sulphur bac-
teria) and fungi.
2. The free-living group composed principally of bacterial-feeding and
saprophytic protozoans, such as Opercularia, Vorticella, Colpidium, Uron-
ema, Arcella vulgaris, and Bodo spp.
3. The scouring group, with Nematode worms as the sole representa-
tive: This group plays a minor role in many high-rate filters, although
there are some notable exceptions.
The trend of increase in the population of the entire microbiota toward
the close of these investigations demonstrated the importance of an ade-
quate supply of food in a sewage filter. This increase in numbers of organ-
isms was accompanied by an increased efficiency of the filter as a treatment
unit.
Contact AERATION (Hays Procsss)
This process of biological treatment is similar to activated sludge
except that with activated sludge, the sewage-sludge mixture is churned
freely in open aeration chambers, while in contact aeration large asbestos
plates are suspended 2 inches apart throughout the aeration tanks to pro-
vide a substrate for the growth of the microbiota. Most plants of this type
have two such aeration chambers placed in series with 3 sedimenation units
arranged as follows: Primary sedimentation tank, primary aerator, inter-
mediate sedimentation tank (clarifier), secondary aerator, and final
clarifier.
The proponents of the contact aeration process claimed a real advan-
tage for their process owing to the establishment of a “‘biological gradient”
which apparently is akin to the succession of organisms in a polluted stream
below a sewer outlet (Griffith 1943). This presupposed the maintenance
of straight-line flow throughout the plant with no recirculation, as occurs
in some other methods of biological treatment. Our studies showed that
where plants of this type were operating beneath their designed capacity,
10 LIMNOLOGY, WATER SUPPLY AND WASTE DISPOSAL
the “biological gradient” could be demonstrated. Near the influent of the
primary aerator in one instance, the growth was very heavy, filling the
spaces between the plates in places. This condition was accompanied by
an unhealthy growth of the bacterial slime, Zoogloea ramigera, and the
presence of numerous anaerobic flagellate protozoans. Myriads of green
and red sulphur bacteria as well as the green alga Chlorella vulgaris, and
the diatom, Navicula sp. occurred where the light could reach them. Free-
living bacteria were also abundant in this part of the aerator, but no
ciliate or amoeboid protozoans were to be found. Near the outlet of this
aerator, however, there were large numbers of ciliate and flagellate proto-
zoans which were subsisting largely on bacteria in the sewage. In the
secondary aerator, the microbiota showed continued improvement. The
appearance of the slime on the plates indicated a healthy condition, and
dense pink colonies of rotifers occurred on the upper portions of some plates.
Moreover, large numbers of Opercularia sp. occurring in the secondary
aerator, indicated that an advanced stage of purification of the sewage
had been reached.
Among the plants of this type there were several instances where
overloading caused a failure of the process, as was evidenced by oxygen
depletion in the aerators and a septic condition throughout. Anaerobic
bacteria and protozoans thrived in a manner similar to what is expected
in a digestion chamber for sludge. According to Lackey and Dixon (1943)
there was “. .. oxygen starvation in the midst of plenty.” Sometimes, where
such difficulty was encountered, the biological gradient was modified by
interposing a trickling filter in the system or recirculating some of the flow.
In every case, the results were good. We are to conclude from this that
the maintenance of the aerobic activity among the microbiota is as impor-
tant in a sewage plant as it is in a stream, if a condition of nuisance is
to be avoided.
TRICKLING Fitters MopIFriED FoR BACKWASHING
The microbiota in the trickling filters at South St. Paul is abundant
and varied. The filters are not housed; therefore the sunlight on the sur-
face rock stimulates the growth of algae and diatoms. Chief among these
are Chlorella sp., Oscillatoria tenuis and Navicula spp. Moreover, some
organisms were found in a sample taken during backwashing operation
that are rarely found in trickling filters. These are Macrobiotus, the water
bear, Aelosoma hemprichi, Pristina sp., and Dero sp. The first is a Tardi-
grade, the other three are aquatic annelids. Although snails have often
been reported from low-rate beds with intermittent dosage of sewage, their
occurrence on high-rate units, such as these at South St. Paul, is unusual.
Several Physa sp. have been found at a depth of 1-2 feet. In addition to
these rather unusual organisms, there are representatives of the higher
bacteria, fungi, protozoa (rhizopods, flagellates and ciliates), rotifers and
insect larvae.
Each filter is backwashed every two weeks with 450,000 gallons of
plant effluent applied through the underdrains of the filters. The action of
+
MICROBIOTA OF SEWAGE TREATMENT PLANTS IN STREAMS 11
the reversed flow is enhanced by the introduction of forced air through
openings in a pipe grid system imbedded near the base of each filter. The
procedure requires about 12 minutes and is effective in removing huge
quantities of sewage solids and biological film. Judging by the myriads of
filter flies in all stages of development which are visible on the surface of
the wash water leaving the filter, this procedure may be cited as a means
of fly control.
The samples taken near the beginning of the backwash contained more
than twice as many binding organisms as at the close of the operation, but
the reverse was true of the free-living organisms and the scouring com-
ponent. Apparently, the first masses of binding organisms were loosened
quickly from the upper surface of the filter, but the majority of the other
organisms resided deeper in the bed and required more time to be dislodged.
The control sample from the effluent of the filters under normal operating
conditions indicated some natural sloughing of solids with about one-third
the number of binders, one-tenth as many free-living forms and but a trace
of scourers in comparison to the average concentration of the effluent from
the backwash.
The series of 13 samples which represent the vertical section of a
trickling filter disclosed several interesting facts. But, first, it is to be noted
that the concentrations given in Table III represent numbers per mm of
film but do not give any clue to the thickness of the film or its mass per
unit volume of stone media. Tests have shown, however, that efficiency
of the film is a function of surface area and not mass. Table III indicates
that among the binding organisms, Zoogloea ramzgera is the predominant
organism throughout the filter, but it is most abundant, and, from its
appearance, most active in the section from 6 to 30 inches in depth. The
large numbers of sewage fungus, Sphaerotilus natans, present on the surface
of the filter on the underside of the upper rocks, may be attributed to the
fact that the carbohydrates, upon which this organism feeds, are assimi-
lated largely in the upper portion of sewage filters. The abundance of the
white sulphur bacteria throughout the remainder of the section is con-
sistent with previous tests on high-rate filters. Among the free-living organ-
isms, predominance is shared by ciliates, rhizopods and flagellates alike.
Although the minute nematodes outweigh the filter flies in numerical pre-
dominance, the latter are probably the more important component of the
scourers. Moreover, the oligochaetes, such as Dero sp., although few in
number, exert a potent influence on the reduction and stabilization of
sewage solids and assist in clearing the voids between the rocks to improve
ventilation. The importance of these and other scouring organisms in sew-
age filters and some recent developments in methods for their control should
not be overlooked.
RECENT DEVELOPMENTS IN SELECTIVE ConTROL OF MICROBIOTA IN
SEWAGE PLANTS -
Among the experts on sewage treatment in England, there are many
who advocate the cultivation of a balanced scouring fauna on sewage filters
LIMNOLOGY, WATER SUPPLY AND WASTE DISPOSAL
12
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MICROBIOTA OF SEWAGE TREATMENT PLANTS IN STREAMS 13
in order to increase aeration, to prevent ponding and to assist in stabiliz-
ing sewage solids. Nuisance from adult filter flies (Psychoda spp.) is at a
minimum where the population of other macrofauna such as chironomids
is sufficient to control them. Nevertheless, a certain amount of fly trouble
is considered to be inseparable from the low-rate filter (Lloyd 1945).
In this country, however, the benefits derived from these organisms
seem, in the opinion of the majority of sewage plant operators, to be over-
shadowed by the nuisance which they create in the immediate vicinity of
the plants. Moreover, from the southern part of this country Brothers
(1946) reported such enormous numbers of filter flies on certain high-rate
filters that not only was practically all of the growth consumed but the
filter bed and pipe lines became clogged. Numerous methods of control
had been tried through the years prior to World War II from chlorination
to flooding the filters for extended periods. One operator perfected the
unique, if hazardous, method of spraying gasoline on the surface of the
filter and igniting it. Most of the earlier methods had the one common dis-
advantage of injuring the biological film.
During the war some significant experiments on the control of filter
flies by the use of DDT were conducted under the sponsorship of the U. 8S.
Army Sanitary Corps. Brothers’ (1946) experiments at Camp Fannin,
Texas, demonstrated the effectiveness of DDT when application is by the
batch method and the chemical is introduced into the sewage as it is sprayed
on the filter. The optimum concentration of one part per million was effec-
tive when a holding period of one hour was provided. The effectiveness
of such a treatment should be apparent for about 30 days.
Although the investigation of Carollo (1946) in this field was con-
ducted independently from Brothers’ investigations, there is excellent agree-
ment in the results. Carollo, however, applied the DDT emulsion to the
filter with the sewage over a 24 hour period at the rate of 1 part per mil-
lion based upon the 24 hour flow.
Examination of the microbiota of the test filters following the appli-
cation of DDT confirmed the selectivity of the chemical. According to
Carollo, snails became more abundant after each treatment, and sewage
filter bacteria were not killed in concentrations up to 100 parts per million.
Since the time of these investigations, there have been others which
confirm them in similar situations and extend the range of possibilities of
DDT in the selective control of the microbiota in sewage plants. Our
knowledge, however, is insufficient with regard to the residual effect of
DDT on receiving waters.
SUMMARY AND CONCLUSIONS
1. The term microbiota is a collective one, including microscopic and
near-microscopic organisms from the higher bacteria through insect larvae.
For convenience in discussing the biology of sewage plants, the organisms
are divided into the following 3 groups on the basis of the functions which
they perform: Binding, free-living and scouring organisms.
14 LIMNOLOGY, WATER SUPPLY AND WASTE DISPOSAL
2. Self-purification in streams and in sewage treatment plants is dis-
cussed. Many of the processes are similar, but in general the reactions
observed in a sewage plant are accelerated. This is attributed to the action
of surface, contact and interfacial forces which operate as a group in
trickling filters, contact aeration tanks and other biological treatment
units. The biological film, with its teeming life, removes food from the
sewage with which it comes in contact and discharges waste products to be
carried away with the effluent.
3. Many of the organisms which are important agents of self-purifica-
tion in streams are also found in sewage treatment plants.
4. The importance of an adequate supply of food in a sewage filter
was illustrated by the effect of changes in operation on the microbiota of
the secondary filter at Owatonna, Minn.
5. Studies on the biology of contact aeration showed the importance
of an adequate supply of dissolved oxygen in the aerators. Where plants
were operating beneath their designed capacity, the biological gradient,
which is apparently akin to the succession of organisms in a polluted stream,
could be observed. Experience has shown, however, that where septic condi-
tions have been created by overloading, the most effective means of correct-
ing the condition is to alter the succession of organisms either by inter-
posing additional treatment units or by recirculating some of the sewage.
6. An unusual opportunity for examining the abundant and diverse
microbiota on trickling filters was afforded at South St. Paul, not only at
the time of backwashing, but also when a filter was opened for repair.
Examinations of the microbiota at the beginning and toward the end of
the 12 minutes required for the backwashing process indicated some differen-
tial in the rate of removal of the organisms. A control sample of the com-
bined effluent from the filters confirmed the efficiency of the process as a
means of removing excessive microbiota and solids. Moreover, this was
an excellent demonstration of control of filter flies. The examination of
the vertical series of samples showed some noticeable variation in the con-
centration of certain organisms, as for example Sphaerotilus natans, Zoo-
gloea ramigera and Chlorella vulgaris; otherwise, the population of micro-
biota was reasonably uniform throughout the section.
7. Recent experiments in the control of filter flies in trickling filters
indicate that an amount of DDT emulsion equivalent to one part per mil-
lion of the total daily flow of sewage is highly effective in controlling the
flies (larvae, pupae and adults) in the dosed area. When applied with the
sewage, DDT does not destroy the biological film or cause it to unload or
slough off. There are, however, insufficient data on the residual effect of
the DDT on aquatic life in receiving waters.
MICROBIOTA OF SEWAGE TREATMENT PLANTS IN STREAMS 15
REFERENCES CITED
Anonymous. 1892. “Cultivation Filters” for sewage disposal. The London Engineer,
p. 330.
BrotuHers, W. C. 1946. Experiments with DDT in filter fly control. Sewage Works Jour.,
18(2): 181-207.
Carouto, J. A. 1946. Control of trickling filter flies with DDT. Sewage Works Jour.,
18(2): 208-211.
GrirFiTH, L. B. 1948. Contact aeration for sewage treatment. Engin. News-Rec., 130(4):
138-142.
Imuorr, K. anp Fair, G. M. 1940. In, Sewage Treatment. John Wiley and Sons, Inc.,
New York.
Lackey, J. B. anp Drxon, R. M. 1948. Some biological aspects of the Hays process of
sewage treatment. Sewage Works Jour., 15(6): 1139-1152.
Luoyp, L. L. 1945. Animal life in sewage purification processes. Abst. of preprint in
Sewage Works Jour., 17(5): 1056-1058.
Mus, H. F. 1890. Natural purification of sewage. Lend a Hand, 5(9): 598-606.
Puetps, BH. B. 1944. In, Stream Sanitation. John Wiley & Sons, Inc., New York.
Watton, G. 1943. In, High Daily Rate Trickling Filter Performance. Published under
the direction of the Board of State Health Commissioners, Upper Mississippi River
Basin Sanitation Agreement, Madison, Wis.
SOME EPIDEMIOLOGICAL AND BIOLOGICAL PROBLEMS
IN WATER-BORNE AMOEBIASIS
By SHIH L. CHANG
DEPARTMENT OF SANITARY ENGINEERING, GRADUATE SCHOOL OF ENGINEERING AND
SCHOOL OF PUBLIC HEALTH, HARVARD UNIVERSITY, CAMBRIDGE, MASS.
INTEREST in the problem of amoebiasis in this country reached a
climax in the few years following the Chicago epidemic of amoebic
dysentery in 1933 (Natl. Inst. Health Bul.). Toward the end of the thirties,
the problem was more or less tossed out of the window and attracted atten-
tion only from those interested in tropical diseases. Although it has been
estimated that from 5 to 10% of the general population pass the cysts of
Entamoeba histolytica (Craig and Faust 1943), the infection has not been
considered a serious public health hazard. This is partly due to the fact
that in most cases, the infection is in a quiescent state, relatively few cases
developing clinical amoebiasis which requires medical care, and partly due
to the fact that the highest incidence of even quiescent infections has been
found in those localities where health problems have not yet received full
attention of health authorities.
While it cannot be denied that in spite of the world-wide occurrence
of quiescent amoebiasis, amoebic dysentery and liver abscess are usually
diseases of the tropics and subtropics, the Chicago epidemic has clearly
shown that under certain circumstances, severe clinical amoebiasis may
occur in epidemic form even in the temperate zone. It may also be pointed
out that while the carrier rates were high in the Southern States, e.g., 17.3,
11.4 and 36.4% in Tennessee and 25.9 and 14.9% in New Mexico, they were
also impressive in some of the surveys made in the Northern States, e.g.,
4.6, 7.7, and 10.7% in Minnesota and 4.1 and 11.1% in Pennsylvania (Craig
and Faust 1943). These carriers not only constitute a potential source of
infection to others, but may themselves develop amoebic dysentery when
they enter the tropics or subtropics, or when certain changes take place in
the alimentary canal.
The successful control of an infectious disease demands a thorough
understanding of its mode of transmission. Unfortunately, it is an extremely
difficult task to ascertain the mode of transmission of some infectious
diseases. For instance, in spite of extensive epidemiological and experi-
mental studies on human poliomyelitis in the last 15 years, we are still
in the dark as to how this infection spreads in a community. Controversial
opinions also exist on the mode of transmission of amoebiasis. In places
such as mental institutions and orphanages where water supply is well
controlled and where personal hygiene of an overcrowded population is
usually bad, direct contact and contamination of food and drink by car-
riers are probably the only two routes by which amoebiasis spreads. How-
16
EPIDEMIOLOGICAL AND BIOLOGICAL PROBLEMS 17
ever, as to the spread of the infection in a large community, two schools
of thought seem to have prevailed, one of which emphasized the importance
of contaminated water supply while the other stressed the presence of car-
riers among food handlers.
Many epidemiologists have not yet fully accepted the view that
amoebiasis is water-borne. The skepticism seems to be based on the fact
that amoebiasis in general does not follow the epidemiological pattern of
classic water-borne bacterial diseases. For instance, amoebic infection is
usually not directly traceable to water supply; it is not explosive in nature;
and the cysts of EL. histolytica have not been demonstrated in water. The
Chicago epidemic, in the opinion of these epidemiologists, is so unusual that
it should be considered as an exception rather than the rule.
In an attempt to ascertain the role played by water in the spread of
amoebiasis, the author has endeavored in the first two sections of this paper
to bring together and analyse the important reports pertaining to this sub-
ject and to discuss certain problems encountered in determining the mode of
transmission of this protozoan infection.
Epidemiologically speaking, the mode of transmission of any infectious
disease is generally detected by a close correlation of the disease in one way
or another with its source of infection. In establishing this relationship, the
following conditions are desirable:
(1) The infection should have a relatively short incubation period.
(2) The infection should give rise to certain distinct clinical symp-
toms that call for medical attention, thus establishing the diag-
nosis.
(3) The causative organism of the disease should be demonstrable
in the transmitting agent, or agents.
Unfortunately, not all infectious diseases satisfy these above-mentioned
conditions. This is particularly true in the case of amoebiasis which has
certain features that make the establishment of the relationship of the
infection to its source extremely difficult under ordinary circumstances.
These features are discussed in the subsequent section of the paper.
I. Certain PEcuULIAR CLINICAL FEATURES OF AMOEBIASIS
A. Symptomless Infection. One of the characteristics of the behavior
of EH. histolytica is its great tendency to produce asymptomatic infection,
particularly in the temperate zone. Ingestion of the cysts of E. histolytica
with subsequent appearance of the organism in the stool does not necessarily
mean that the infected person is going to develop clinical symptoms. In
fact, most of the infected cases develop into a quiescent state. This phe-
nomenon is not only confirmed by the existence of carriers in various coun-
tries (Craig and Faust 1943) but also by the outstanding work of Walker
and Sellards (1913) in the Philippines. These two authors fed a faecal
suspension containing cysts of H. histolytica from a carrier to 20 volunteers
and found that 18 became infected and 2 did not. Among the 18 parasit-
18 LIMNOLOGY, WATER SUPPLY AND WASTE DISPOSAL
ized, only 4 developed dysentery, respectively 20, 57, 87, and 95 days after
the feeding. Some of the quiescent cases were followed for over 2 years and
never showed symptoms related to the infection. Furthermore, Wenyon and
O’Conner (1917) reported that of the 106 carriers of E. histolytica found
among 1979 healthy persons in Egypt, only 16 gave any history of
dysentery.
Hence, it seems that even in the tropics and subtropics, the majority
of cases of amoebiasis exist in the native population in a quiescent state.
For these asymptomatic cases, the determination of the source of infection
would be extremely difficult, if not impossible.
B. Secondary Factors in the Etiology of Amoebic Dysentery. Although
amoebic dysentery has been known to us since the end of the last century,
we must admit that we are still uncertain about the factors concerned in
the etiology of the clinical disease. As stated before, introduction of E.
histolytica into the human intestine oftentimes results in a carrier state and
dysentery may not develop until certain secondary factors are present.
Evidently the factors involved in the development of dysentery are complex.
Some laboratory investigators and clinicians (Dobell and O’Conner 1921;
Wenyon 1926; James 1927; Westphal 1937; Deschiens 1938; Nauss and
Rappaport 1940; Manson-Bahr 1947) have reached the conclusion that
under normal conditions, EH. histolytica is a harmless parasite in the human
intestine and will not invade tissue and provoke dysentery or liver abscess
until other factors exist, such as injury of the tissue by pathogenic bacteria
or chemical agents. The fact that many of the German soldiers who had
been carriers for years in Germany developed amoebic dysentery during
outbreaks of bacillary dysentery in North Africa made Horster (1943)
believe that it was the presence of pathogenic bacteria such as the shigellae
that damaged the tissue and provoked clinical amoebiasis in those carriers.
Very recently, Wenyon (1947) has suspected that the Chicago epidemic
might have been an outbreak of bacillary dysentery among a population
with a high carrier rate of HE. histolytica.
The other group of investigators led by Craig (1944), Faust (1941)
and Johnson (1941) believe that EH. histolytica is pathogenic under all cir-
cumstances. While there are some reports in the literature of the occur-
rence of typical amoebic ulcers in the intestine of apparently symptomless
persons, these observations have usually been made in the tropics and sub-
tropics. Those who favor this belief frequently quote the careful observation
of Faust (1941) made on 202 autopsies of accidental death in New Orleans
in which £. histolytica was found in 13, with 8 showing bowel lesions but
only 5 with amoebae in the lesion. Commenting on Faust’s observation,
Napier (1947) has very recently pointed out that in none of these autopsies
was a typical amoebic lesion demonstrated, and the description of the
lesions, particularly of the superficial erosions, do not distinguish them
from post-mortem changes.
In a previous communication, the author (1946) showed that EH.
histolytica is an obligate anaerobe flourishing in natural or artificial media
EPIDEMIOLOGICAL AND BIOLOGICAL PROBLEMS 19
at Ey, values between -350 and -400 millivolts. This strongly reducing con-
dition is apparently provided by the growth activity of the accompanying
bacterial flora. In another communication, the author (1945) pointed out
the importance of ligating the rectum in the establishment of infection in
kittens of 2 strains of E. histolytica which had lost much of their infectivity
through prolonged in vitro cultivation, and felt that the ligation of the
rectum favored the development of pathology not so much because of the
retention of the inoculum, but rather because of changes induced in the
intestine after ligation, particularly changes in the bacterial flora.
It is beyond the scope of the present paper to discuss in detail the
problem of pathogenesis of H. histolytica. There should not be any doubt
that E. histolytica is a pathogenic protozoa. However, parasitism in the
human intestine by a pathogenic protozodn may not always be accompanied
by pathological changes. Haemolytic streptococci are unquestionably patho-
genic bacteria; but they are frequently found in the throat of healthy
individuals. The same thing has been shown to be true of many other patho-
genic bacteria.
Whatever may be the actual mechanism by which the bacterial flora
affects the pathogenic activity of H. histolytica, it is probably a more com-
plex phenomenon than the mere damaging of the tissue to favor invasion
by the amoebae. The provision of anaerobic conditions by the bacterial
flora, in the author’s opinion, may not only favor the survival and multipli-
cation of amoebae but may also play a leading role in facilitating the tissue
invasion by the latter. In one experiment (unpublished data) in which the
author fed culture-induced cysts of a strain of amoeba that had lost much
of its infectivity for kittens to 6 kittens, 2 animals had the rectum ligated;
2 had the rectum ligated and also received 10 ml of a rich culture of
Clostridium perfringens in gelatin; and 2 were control. The first 2 animals
became sick after the 5th day and were sacrificed on the 9th day. At
autopsy, the caecum of each animal was punctured with a platinum elec-
trode and a capillary pipette containing saturated KCl in 2% agar, con-
nected to a potentiometer. The potentials were measured against a calomel
reference cell and the E, values of the caecal contents of both animals were
found to be -275 and -282 millivolts respectively. Both caeca showed a few
patches of superficial ulcers of the mucosa with many trophozoites in the
ulcers but outside the basement membrane. The second two animals that
had received the clostridium culture were sick on the 3rd day and dying
on the 6th day. They were sacrificed. At autopsy, the Ey, values of the
caecal contents were recorded as -375 and -392 millivolts respectively, and
both caeca showed several typical amoebic ulcers with numerous tropho-
zoites in the submucosa. The control animals remained uninfected and
were sacrificed 7 days after feeding. The E, values of their caecal contents
were -185 and -198 millivolts respectively and no lesion was noticed at
autopsy. Although the number of animals used was small, the unique results
provide some basis for explaining the establishment of amoebic infection.
It is anticipated that the ingestion of cysts of EL. histolytica by some indi-
20 LIMNOLOGY, WATER SUPPLY AND WASTE DISPOSAL
viduals who have an intestinal bacterial flora which does not provide
conditions anaerobic enough for the perpetuation of the amoebae, may
not produce any infection at all. In those persons whose intestinal bacterial
flora furnishes a moderately anaerobic condition, the ingestion of cysts
may produce an infection without apparent pathology. In those persons
whose intestinal bacterial flora creates a profound anaerobic condition
which may extend into the mucosa, the introduction of amoebic cysts will
establish infection and produce amoebic lesions.
Furthermore, it is not entirely unlikely that the amoebae do secrete a
cytolysin for their parasitic life in the tissue and that the secretion of this
cytolysin may be facilitated by the profound anaerobiasis.
However, there may be other factors involved in the pathogenicity of
E. histolytica, such as the virulence of the amoeba, the nature of the diet,
the physiological condition of the intestine, particularly its ability to resist
the changes produced by the normal bacterial flora, and the immunity
status. All of these may affect in one way or another the development of
clinical amoebiasis.
C. Primary and Secondary Amoebic Dysentery. Whatever the actual
mechanism involved in the development of amoebic dysentery, from the
epidemiological point of view, the clinical cases may be divided into two
groups, namely: the primary and secondary dysentery. The primary cases
are those that develop dysentery following the ingestion of infective
material. They could be due to either introduction of amoebic cysts of a
virulent strain into the intestine where conditions favorable for develop-
ment of dysentery exist, or introduction of such amoebic cysts accompanied
by a bacterial flora which is capable of altering the normal intestinal flora
and favors tissue invasion. This type of case usually occurs during epi-
demics or in small outbreaks in poorly sanitated or unsanitated tropical
or subtropical regions. Examples are the cases in the Chicago epidemic, and
those developed after consuming grossly polluted water in the tropics
and subtropics as cited by Strong (1944) and observed in the Burma cam-
paign in World War II (personal communication). It is in this kind of
cases that the incubation period can be reasonably accurately determined
and source of infection established.
The secondary cases are those that have been carriers for months or
years and develop amoebic dysentery upon introduction of certain second-
ary factors. The type of case in this group is illustrated by the carriers
who developed amoebic dysentery during outbreaks of bacillary dysentery
as observed among German soldiers by Hauer (1942) and Horster (1943)
and among the Allied troops in North Africa (Coggeshall 1943) and the
Near East (Fairley and Boyd 1943). In this type of case, the determina-
tion of the course of infection is very difficult, since the disease is not
correlated with the primary source but with the occurrence of secondary
factor or factors.
D. Incubation Period of Amoebiasis. Under natural conditions, it is
impossible to know the incubation period of asymptomatic amoebiasis. In
EPIDEMIOLOGICAL AND BIOLOGICAL PROBLEMS 21
the quiescent cases in Walker and Sellards’ experiment (1913) the average
incubation period was about 9 days. Even if we take for granted that the
incubation period of naturally infected cases is 9 days, it would not be
of any help in ascertaining the date of infection unless the population is
constantly examined for the presence of the amoebae in the stool.
In the secondary cases of amoebic dysentery, the incubation period,
as stated before, is very obscure, since it is not the period between the
ingestion of amoebic cysts and the development of clinical amoebiasis, but
the period elapsed after the secondary factors come into operation.
Hence, from a practical view-point, it is only in the primary cases
of amoebic dysentery that the incubation period can be determined with
a fair degree of accuracy. In the four cases of dysentery observed in
Walker and Sellards’ experiment, the incubation period was 20, 57, 87,
and 95 days respectively. The incubation period of the cases involved in
the Chicago epidemic has been considered by Wenyon (1947) as too short
for amoebic dysentery. Wenyon stressed in particular the few cases hav-
Ing an incubation period of two days and thought that, in order to pro-
duce amoebic dysentery with so short an incubation period, the cyst-
contaminated water must have been so heavily polluted that it would have
shown physical impurities to arouse objections on the part of the guests.
In the author’s opinion, there must have been misdiagnosed cases in that
epidemic, in view of the fact that physicians and technicians did not
become aware of the existence of the epidemic until it was over and most
of them were probably not too familiar with the diagnosis of amoebiasis.
Hence, it is not unlikely that those few cases with an incubation period of
less than one week might have been cases of bacterial enteric infection;
but there is not much doubt that the epidemic, as will be shown later,
was itself amoebic dysentery. Furthermore, the incubation period of the
4 cases in Walker and Sellards’ experiment cannot be regarded as uni-
versally applicable since the virulence of the amoeba, the susceptibility of
the host, and the nature of the intestinal bacterial flora may vary from
strain to strain, person to person, and place to place.
In fact, the incubation period of the majority of cases in the Chicago
epidemic was not too different from that observed in other studies. Of the
216 selected cases who resided in the two hotels involved for a short enough
time to allow the determination of incubation period, 25% gave an incu-
bation period of less than 11 days, 25% between 12 and 20 days, 25%
between 21 and 36 days, and the remaining 25% between 37 and 120 days.
It may be interesting to point out that, because of the relatively long
incubation period in the majority of cases, the Chicago epidemic was not
recognized during the outbreak as there were only 15 cases which were con-
nected with the two hotels reported to the Chicago Board of Health, and
that the epidemic was only disclosed by the questionnaire survey made later
when suspicion was aroused by a report on amoebic dysentery at the
American Public Health Association Convention held in Indianapolis (Natl.
Inst. Health Bul.).
22 LIMNOLOGY, WATER SUPPLY AND WASTE DISPOSAL
II. THe Rous or PottutTep WATER AS A TRANSMITTING AGENT OF AMOEBIASIS
As early as 1926, Craig mentioned the possibility of water-borne
amoebiasis. Clark (1925) reported the marked reduction in post-mortem
incidence of amoebic infection in Panama following the introduction of a
modern water supply; but the evidence has been considered as too non-
specific to support the view that amoebiasis is water-borne, since many
other factors, such as improvement of personal hygiene and change of eat-
ing habits, could have altered at the same time and might also have
affected the incidence of amoebic infection. Nevertheless, there have been
accumulated a few substantial facts that provide sufficient ground to believe ©
that polluted water may be one of the most important sources of amoebiasis.
A. The Chicago Epidemic. In spite of the skepticism expressed by
some epidemiologists and eminent tropical disease experts, the Chicago
epidemic of amoebic dysentery, in several of its essential features, still
stands out as an example of water-borne amoebiasis. As stated before,
Wenyon (1947) expressed skepticism on the basis that the incubation
period was too short for amoebic dysentery; but the number of cases hav-
ing an incubation period of less than one week was so small that they
should carry no weight in judging the nature of the epidemic.
Although the finding of EH. histolytica-like cysts in the cross-connection
pipe removed at the time of inspection (Natl. Inst. Health Bul.) served
only as weak evidence for the water-borne nature of the epidemic, there
were a few essential observations that strongly supported the water-borne
theory. First, if the epidemic were bacillary dysentery, there should
have been a very large number of cases of bacillary dysentery noticed
during the early part of the epidemic. On the contrary, the epidemic
was reported to be uncomplicated by the existence of outbreaks of bacterial
enteric infections (Natl. Inst. Health Bul.). Second, the fact that amoebia-
sis, including the asymptomatic infection, has been successfully controlled
in the two Chicago hotels after the sanitary defects were corrected is also
strong evidence that the source of infection of that epidemic was of water
origin. Third, the recent outbreak of bacillary dysentery in Kansas (Kin-
naman and Beelman 1944) in which 3000 cases were reported was not
complicated by cases of amoebic dysentery.
B. The Chicago Stockyard Fire Outbreak. In the Chicago Stockyard
fire in 1934 (Hardy and Spector 1935), at least 11 cases of amoebic
dysentery were noticed along with over 300 cases of dysentery and 78
cases of typhoid fever among the firemen and some spectators who drank
water from a pipe which was used to supply water to the stock and fed
with sewage-polluted water and sewage effluent. It is of particular interest
to note that among the 216 firemen who developed enteric infection of
various degrees of severity, 57% showed cysts of H. histolytica in their
stools, while only 15% of 161 firemen who did not drink the polluted water
and consequently were not infected, had the cysts. While it could be argued
that the 11 cases of amoebic dysentery might have been secondary cases
developed in carriers, the much higher percentage of cyst passers among
EPIDEMIOLOGICAL AND BIOLOGICAL PROBLEMS 23
the firemen who drank polluted water than among those who did not,
serves as good evidence that many of those cyst passers among the higher
percentage group were infected by the polluted water they drank.
C. Discovery of Cysts of E. histolytica in Sewage and Sewage Effluent.
Recently, Gordon (1941) reported that the effluent of the Moscow sewage
discharging into a river had been found to contain EL. histolytica-like cysts
constantly during a period of 3 years of examination, and that stor-
age of the effluent for 614 hours in a tank failed to remove all cysts from
the supernatant. Cram (1943), in this country, reported that HE. histolytica-
like cysts were occasionally found in the sewage sludge both from munici-
palities and from army camps, and that storage and sewage treatment
failed to remove all the cysts from the sewage effluent. In a previous
report, the present author (1945a) showed that the cysts of EH. histolytica
have a specific gravity of about 1.06 and that even in perfectly quiet, pure
water, it would take 2 or more days for the cysts to settle through a 5-foot
depth at 10-28° C. These results imply that in places where carriers
exist, the sewage will contain the cysts, and some of these cysts are likely
to remain in the effluent after treatment. Pollution of water with this
sewage or sewage effluent will render the former a source of amoebic infec-
tion.
III. BroLtocicaL PRoBLEMS IN WATER-BORNE AMOEBIASIS
Having shown that polluted water supply may constitute one of the
most important sources of amoebic infection, this section of the paper
attempts to bring out some of the biological problems related to the cysts
of EH. histolytica in order to furnish information on the purification or dis-
infection of water for removal or destruction of the amoebic cysts that may
be present.
A. Cultivation of E. histolytica in Artificial Media. To detect the
presence of cysts in possible agents of transmission, or to determine the
viability of cysts in survival tests requires cultivation of the cysts in arti-
ficial media. Excystation of the mature cysts and multiplication of the
trophozoites result in a positive culture. Although several good entamoeba
media have been successfully used by protozoologists, obtaining positive
culture of the organism is not simple. As shown in a previous report by
the author (1946), H. histolytica requires a moderately anaerobic condition
for excystation and a profound anaerobic condition for perpetuation, and
these anaerobic conditions are furnished by the growth activity of an
accompanying bacterial flora. This bacterial flora must also not produce
unfavorable pH range in the culture. These growth requirements of the
amoebae are not provided by every kind of bacterial flora. Therefore,
unless the cultures are handled by experienced persons, cultural results
obtained in tests for the presence or survival of amoebic cysts may be
misleading.
B. Survival of Cysts of E. histolytica in Water and Sewage. In a
previous report by the author (1943), it was shown that culture-induced
24 LIMNOLOGY, WATER SUPPLY AND WASTE DISPOSAL
amoebic cysts may survive in sterile normal saline, distilled water, river
water, or raw sewage for a few days to almost 3 months depending on
the temperature of the suspending medium. With a cyst concentration
of about 1 million per ml of fluid, the survival time may be expressed by
the equation: t — 87.2 x 10~-°**T, where ¢ is the time in days and T tem-
perature in °C. The survival time is essentially the same whether the
suspending fluid is sterile normal saline, river water, or raw sewage.
C. Sedimentation of Cysts of E. histolytica in Water or Sewage. As
stated before, the specific gravity of amoebic cysts was found to be about
1.06. Assuming that the modal diameter of amoebic cysts is 15 microns
(except. in the small race which may have an average diameter of 10
microns), the settling rate in perfectly quiet, pure water is about 1 foot
in 16 hours at 10° C and in 10 hours at 25° C. Under natural conditions,
the settling of cysts in polluted water is bound to be much slower, since the
water is usually flowing and has convection currents and a higher specific
gravity than pure water. This, of course, refers to the isolated cysts only.
For those that are embedded in solid matter, the settling rate would be much
faster. Hence, while the embedded cysts may be settled out in polluted
water, one cannot depend on storage of water or sewage for removal of
cysts unless a long period of storage is used.
D. Removal of Amoebic Cysts by Filtration, Flocculation and Sedi-
mentation, or by Both Methods. Spector, Baylis and Gullans (1934) have
shown the effectiveness of the rapid sand filter in removing cysts from
water. In the preparation of purified cyst suspensions for cysticidal
studies, the author (1944) has used a small sand filter composed of a 2-
inch layer of sand of size between 100 and 140 mesh to separate cysts
from starch grains and found that such a sand filter removes practically
all cysts from the suspension if the sand is fresh and undisturbed and if
no pressure is exerted on the filter. Brady and Black (1945) reported that
the portable pressure filters used by the Army removed 88% of the cysts
from the water filtered at a rate of 15 gallons per minute. The cyst
removal was increased to 99% if flocculation was applied to the water
before filtration. These authors also reported that the diatomaceous earth
filter developed by the Army removed almost all the cysts from the treated
water.
Brady and Black (1945) reported that flocculation with good floc
formation followed by sedimentation for 2 hours removed over 99% of the
cysts from the supernatant. In a few tests made by the author (unpub-
lished data), it was found that good flocculation of a river water by the
use of alum followed by sedimentation for 2 hours removed practically all
the cysts (in water containing 100 cysts per ml) from the supernatant
of 10 cm in depth, and that the settled flocs contained cysts in lumps and
unharmed. However, with poor flocculation, only 90% to 95% of the
cysts were removed. Hence, it seems that this method of water purifi-
cation, if properly done, may remove all the cysts in water.
BE. Resistance of Cysts of E. histolytica to Acids and Bases and Various
EPIDEMIOLOGICAL AND BIOLOGICAL PROBLEMS 25
Disinfectants. In the last 5 years, numerous experiments on the destruc-
tion of amoebic cysts in water by various chemicals have been conducted
in our laboratory. A few reports by other investigators have also appeared
in the literature. It is beyond the scope of the present paper to deal in
detail with the data on this subject, but it is felt desirable to present here
a brief account of the conclusions reached in our studies and by other
investigators. The early studies in which the eosin staining method was
used (Wenyon and O’Conner 1917; Mills, Bartlett and Kessel 1925; Baylis,
Gullans and Spector 1936) for determining the viability of treated cysts
and the more recent study made by Stone (1937), in which the viability
of the treated cysts was tested by the culture method without restoring
the bacterial flora are not included in this presentation because these
methods of testing the viability of amoebic cysts are unreliable.
1. Acids and Bases. Cysts of E. histolytica are very resistant to acids
and bases. The cysticidal effect seems to be chiefly a function of the hydro-
gen or hydroxide ion concentration. In our studies on water disinfection
(Fair, Chang and Morris 1945), it was found that the culture-induced
cysts were not destroyed by acids at a pH value of 0.5 with a contact time
of 2 hours. With bases reaching a pH value of 14.0, the cysts were
destroyed in 10 minutes; but a pH value of 13.0 showed no cysticidal effect
in 2 hours. Hence, it seems that the OH-ions are more cysticidal than
the H-ions. Unfortunately, this cysticidal pH value is too high to be of
practical use in ordinary water treatment.
2. Halogens and Halogen Compounds. In an earlier report by Chang
and Fair (1941), it was shown that amoebic cysts were definitely more
resistant to active chlorine than vegetative bacteria, such as Hscherichia
colt and that the cysticidal efficiency of active chlorine increased with
lowering of pH value, rise of water temperature, and increase in contact
time, and, to a less extent, with decrease in cyst concentration. It was
concluded that for complete destruction of amoebic cysts that may be
present in water, doses of active chlorine in the lower range of super-
chlorination would be required provided that the pH of the water could
be held below 7.5 and the chlorine demand was not too high. Brady and
his associates (1943) also reported that superchlorination is necessary to
destroy the cysts; but they also noticed that the contact time is more
important than the chlorine dosage, since increase in chlorine dosage some-
times resulted in a lowering of the cysticidal efficiency. In view of the
fact that these investigators used calcium hypochlorite in their tests and
that the increase in chlorine dosage by the use of calcium hypochlorite
automatically raises the pH of the chlorinated water (Fair, Chang and
Morris 1945), thus decreasing the amount of more cysticidal hypochlorous
acid (HOCO1) and increasing the amount of less cysticidal hypochlorite
ions (OC1—), this phenomenon observed by Brady et al. (1943) was
to be expected. It is regretted that these authors did not determine the
pH value of their treated water.
Becker, Burks and Kalieta (1946), working with amoebic cysts
26 LIMNOLOGY, WATER SUPPLY AND WASTE DISPOSAL
obtained from carriers in India, reported that even as much as 10 ppm
of residual chlorine failed to destroy all cysts in water of relatively low
organic content with a contact time of 60 minutes. These authors used
bromthymol blue as an indicator in regulating the pH of the chlorinated
water to neutral. Since organic dyes like bromthymol blue react rapidly
with active chlorine to give false colors, it is apparent that they were
working at unknown pH values. In view of the fact that these authors
used calcium hypochlorite for active chlorine and NaOH for regulating
the pH, it is probable that these authors were working at high pH values.
In two recent reports, the present author (Chang 1944a; 1944b) brought
out the fact that in chlorination studies, the chemistry of chlorine and
chlorine compounds must be thoroughly understood. The effect of pH on
the cysticidal efficiency of chlorine is profound and lies in the alteration
of the proportions of chlorine present as hypochlorous acid and hypochlorite
ions. In the pH range up to 9.0, the cysticidal activity seems to be en-
tirely due to the HOC1 concentration. At 25-28° C and with a contact
time of 10 minutes, about 2 ppm of residual chlorine as HOC1 destroyed
all cysts when a cyst concentration of 30-60 per ml was used. More
recently, we showed that the cysticidal efficiency of hypochlorite ions is
only about 1/300 of that of HOC1 (Chang, Fair and Morris 1945; 1946).
In another report (Fair, Chang and Morris 1947), it has been shown that
the cysticidal efficiency of HOC1 can be expressed by the cysticidal con-
centration-time relationship which is represented by the equation: tC" = k’,
where k’ is the disinfection constant, t the disinfection time in minutes,
C the concentration of disinfectant in ppm, and n the concentration coeffi-
cient of the disinfectant. Substituting the values for HOC1 into the equa-
tion, it was found that,
t= 205C"1 at 3° C.
i SOC muiat 2a 41;
From the value of n, it is seen that the concentration affects the cysticidal
efficiency of HOC1 just as much as the contact time. In the same report
(Fair, Chang and Morris 1946), it has been shown that the temperature
affected the cysticidal efficiency of HOC1 to give a Q,, of about 2.2.
The chloramines and chloramides are definitely less cysticidal than
HOC1. Among the monochloramines and chloramides, ammonia-mono-
chloramine is more cysticidal than the organic compounds or hypochlorite
ion. This is believed to be due to the small molecular size of ammonia-
monochloramine, which penetrates more readily into the cysts than the
larger molecules of organic chloramines and chloramides and negatively
charged hypochlorite ions. Among the organic monochloramines and
chloramides, succinchlorimid seemed to be the most cysticidal. At 23° C
and with a 10-minute contact time, 10 ppm of residual chlorine as ammonia-
monochloramine destroyed all cysts, while the same efficiency was reached
by 80 ppm of residual chlorine as succinchlorimid, or 140 ppm of residual
as monochloramine-T or azochlorimid. It must be pointed out that the
EPIDEMIOLOGICAL AND BIOLOGICAL PROBLEMS 27
results obtained with succinchlorimid were oftentimes irregular, due appar-
ently to its unstability in solution.
The dichloramines are more cysticidal than the monochloramines and
among the dichloramines, ammonia-dichloramine seemed to be the most
cysticidal. About 6 ppm of residual chlorine as ammonia-dichloramine
destroyed all cysts in 10 minutes at 23° C while the commonly used organic
dichloramine, Halazone, reached the same efficiency at a residual chlorine
concentration of 12 ppm (Fair, Chang and Morris 1945; 1946).
Chlorine dioxide as tested in our laboratory, seems to be less cysticidal
than HOCI1 on a basis of ppm as titrable chlorine, and we were uncertain
as to the method for determining the amount of active chlorine in this
compound.
Bromine, in its elemental form, has also been tested in our laboratory
for its cysticidal efficiency. In a small number of experiments, it has
been found that this halogen is slightly less cysticidal than HOC1 on a
weight basis and slightly more cysticidal molecule for molecule (Fair,
Chang and Morris 1945). This is believed to be due to the fact that bromine,
having a smaller hydrolysis constant, exists to a greater extent in elemental
form than chlorine, the elemental forms of the halogens being thought to
penetrate cysts more easily than their compounds. However, bromine
showed a considerably greater loss to the halogen demand of the water
than HOC1.
Iodine has been extensively studied in our laboratory. Its cysticidal
efficiency, as reported by us (Fair, Chang and Morris 1945; 1946) is less
than that of HOC1 on a weight basis but slightly more on a molar basis.
This is again believed to indicate that elemental iodine penetrates cysts
more easily than HOC1. The advantage of elemental iodine as a cysticidal
agent over HOC1 lies in the fact that it is less affected by changes in
temperature, does not form iodomines with ammonia or amino compounds,
and does not impart as much objectionable odor and taste to the treated
water as does HOC1 at the cysticidal level. The cysticidal efficiency of
elemental iodine has also been expressed in concentration-time relationship
as follows:
G—— Wileo Creatine 3©,
Ga NS Crt aiat 0) 21©
b= SUA ip 289 C
The effect of temperature on the cysticidal efficiency of iodine has also
been calculated to give a value of Q,, of 1.6 (Fair, Chang and Morris 1946).
Ozone was reported by Kessel and his associates (1944) to be more
cysticidal than active chlorine. These investigators found that a residual
of 0.1 to 0.3 ppm of ozone (using orthotolidine test) destroyed all the cysts
in water in a few minutes.
The cysticidal efficiency of synthetic detergents has been studied by
Kessel and his associates (1946) and also in our laboratory. In the report
of Kessel et al. (1946), it is noticed that some of the cationic detergents
were cysticidal at a concentration of less than 12.5 ppm. In our reports
28 LIMNOLOGY, WATER SUPPLY AND WASTE DISPOSAL
(Fair, Chang and Morris 1945), we showed that anionic detergents
were noncysticidal at a concentration as high as 20,000 parts per mil-
lion. Neutral detergents, such as Hexyl-resorcinol, were cysticidal at a
concentration of 75 ppm in 10 minutes to 30-50 ppm in 120 minutes.
Cationic detergents were cysticidal at lower concentrations but some were
considerably more cysticidal than others. For instance, Fixanol, Sapamine,
Ceepryn, Zephiran, Ortho-7 and Nopco-QCL were cysticidal at 5-10 to
30 ppm in 10 to 120 minutes, while others, such as Emulsol-660B, were
not cysticidal even at 75 ppm in 10 minutes to 50 ppm in 120 minutes.
The cysticidal efficiency of cationic detergents was found to be affected
by the presence of proteins, lipoids, and probably also by greasy and soapy
substances. Anionic detergents were found to be good neutralizing agents
for cationic detergents (Fair, Chang and Morris 1945; Kessel and Moore
1946).
IV. Discussion
Is amoebiasis an important infection in this country? Besides the
nationwide distribution of cases of quiescent infection, about 3 to 4 thou-
sand cases of amoebic dysentery have been reported annually in the Public
Health Reports of the U. S. Public Health Service in the last 10 years. Of
these reported cases, about one third have been from the State of Missis-
sippi. Hence, it would seem that if amoebiasis is not a serious infection
in the country as a whole, it is so in Mississippi.
While it would be absurd to think that polluted water is important
in spreading amoebic infection in areas where water supply is sanitarily
controlled, it would be equally absurd to think that polluted water is of
no importance in establishing the infection in areas where water supply
is still inadequately controlled. Judgment as to the more important mode
of transmission of this infection must be based on the local conditions
existing rather than on biased opinion.
Since the present paper deals only with the problems in water-borne
amoebiasis, emphasis has been laid on this route of transmission. The
author, of course, has no intention of minimizing the other routes of trans-
mission when circumstances that favor the spreading of the infection by
such routes exist. From the epidemiological problems presented in the paper,
it is apparent that any argument for or against the water-borne theory is
circumstantial in nature, and so are the arguments for or against the theory
of other routes of spreading the infection. If diseases like typhoid and
bacillary dysentery result from unhygienic habits of eating and drinking,
so does amoebiasis. A very careful study of the epidemiology of the amoebic
dysentery as well as quiescent amoebiasis and of the effectiveness of vari-
ous methods of contro] in Mississippi may bring out valuable information
and throw more light on the subject of the mode of transmission of amoebia-
sis.
The biological characteristics of the cysts of H. histolytica brought
together in the present paper provide us sufficient information as to the
EPIDEMIOLOGICAL AND BIOLOGICAL PROBLEMS 29
problems to be encountered in the control of water-borne amoebiasis. From
these characteristics, it is apparent that if polluted water is to be used as
a source of public water supply, it must be considered as a potential
source of amoebic infection and must be treated as adequately as is the
practice in a modern municipal water works, namely, by storage, floccula-
tion and sedimentation, filtration, and chlorination. The cysts that may
be present in the water are completely removed by the combined effect
of the first three methods but will not be killed by chlorination as normally
practiced in water works. If chlorination is the only method available for
destruction of cysts in water, then superchlorination or breakpoint chlorina-
tion must be employed. For emergency treatment of water to destroy
cysts, superchlorination at pH 5.0 to 6.0 followed by dechlorination or treat-
ment with elemental iodine to give a residual of about 4 to 5 ppm in 10
minutes at pH 5.0-7.0 would be satisfactory. The use of 30 to 50 ppm
of some of the best cationic detergents is also feasible, but this treatment
would produce a bitter and slightly soapy water. Ozone is a powerful cysti-
cidal agent, but its use is bound to be handicapped by its low solubility and
the difficulty of distributing it evenly in a large body of water.
It goes without saying that one of the best control measures of amoebia-
sis is a thorough treatment of the cases of amoebic dysentery to prevent
them from swelling the army of carriers and a thorough treatment of all
carriers. While the former can be effectively carried out, the treatment
of all carriers, particularly in areas where the carrier rate is high, would
certainly encounter many difficulties.
V. SUMMARY
In this paper, some of the clinical features of amoebic infection have
been discussed to bring out the difficulties involved in the study of the
epidemiology of this infection for establishing the mode of transmission.
These features are quiescent infection, primary and secondary amoebic
dysentery, incubation period, and the not-too-well-understood factors
involved in the provoking of amoebic dysentery.
The water-borne nature of amoebiasis has been discussed. Evidences
such as the Chicago epidemic, the Chicago Stockyard fire outbreak of
enteric infections, and finding of E. histolytica-like cysts in sewage and
sewage effluent are brought out and analysed to show the probable role
‘played by polluted water in the spread of amoebiasis.
The biological characteristics of the cysts of H. histolytica have been
presented, such as the cultivation of amoebae, the specific gravity and
settling of amoebic cysts in water and sewage, the removal of amoebic
cysts from water by flocculation and sedimentation and by filtration
through sand or diatomaceous earth filters, and the resistance of amoebic
cysts to various water disinfectants, particularly the halogens and halogen
compounds.
At the end of the paper, the thought is expressed that if amoebiasis is
not a serious public health hazard in the United States as a whole, it is
30 LIMNOLOGY, WATER SUPPLY AND WASTE DISPOSAL
so in the state of Mississippi. It is suggested that the study of the epi-
demiology of amoebic dysentery and the quiescent infection, and of the
effectiveness of various methods of control in Mississippi, may throw more
light on the subject of the mode of transmission of amoebiasis in a free
community.
The author is grateful to Dean G. M. Fair, to his colleague Professor
E. W. Moore, and to his friend Dr. D. Weinman for reading this manu-
script and making helpful suggestions.
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and pathogenicity for kittens of H#. histolytica during prolonged in vitro cultivation
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Jour. Infect. Dis., 76: 126.
. 1945a. Sedimentation in water and the specific gravity of cysts of Hn-
tamoeba histolytica. Amer. Jour. Hyg., 41: 156.
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Cuane, 8. L. anp Farr, G. M. 1941. Viability and destruction of the cysts of Entamoeba
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Cuark, H. C. 1925. The distribution and complications of amoebic lesions found in 185
post-mortem examinations. Amer. Jour. Trop. Med., 5: 157.
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EPIDEMIOLOGICAL AND BIOLOGICAL PROBLEMS 31
Dosett, C. and O’Conner, F. W. 1921. In The Intestinal Protozoa of Man. William
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32 LIMNOLOGY, WATER SUPPLY AND WASTE DISPOSAL
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BIOTIC RESPONSES TO STREAM POLLUTION DURING
ARTIFICIAL STREAM REAERATION
By A. F. BARTSCH
WISCONSIN COMMITTEE ON WATER POLLUTION
AND
WARREN S. CHURCHILL
WISCONSIN CONSERVATION DEPARTMENT, MADISON, WIS.
INTRODUCTION
During lumbering days, the Flambeau River carried logs of majestic
pine and hardwood, and even now the water is shaded occasionally by
virgin timber. Its natural beauty is an annual attraction to the fisherman
and vacationist. Aside from these values, the river is efficiently wash-
ing away pulp and paper mill wastes equal in strength to the domestic
sewage from a city about the size of Omaha, Richmond or Oklahoma City.
This report is primarily an account of the way in which the living things in
the stream are affected by this natural clean-up job.
HYDROGRAPHIC AND CULTURAL
The Flambeau River is located in the north-central part of Wiscon-
sin (Figure 1) and drains southwesterly into the Chippewa. The drainage
area of the North Fork, considered in this report, is about 1,150 square
miles with 720 square miles above the city of Park Falls. This area is
mostly cut over land, relatively undeveloped and with a low human popu-
lation. The most prominent cultural feature is Park Falls with a popula-
tion of about 3,200.
Domestic sewage is treated efficiently by the activated sludge process
(Figure 2). Daily B.O.D. population equivalent from this source is 150.
Critical pollution of the North Fork by waste sulphite liquor originating
at a Park Falls mill has been a serious problem for more than 10 years.
The daily B.O.D. contribution from this source was about 189,000 popu-
lation equivalent during the summer of 1946. In years of low stream
flow, conditions became severe as far downstream as Oxbo—25 to 30 miles
from the pollutional source. Dilution by river water alone as a source of
dissolved oxygen has been adequate only when flows approach 2,000 c.f.s—
almost three times average flow.
These conditions led to selection of the Flambeau River as the subject
for experimental artificial reaeration. The project was undertaken as a
cooperative one by the Sulphite Pulp Manufacturers’ Committee on Waste
30
34 LIMNOLOGY, WATER SUPPLY AND WASTE DISPOSAL
Disposal, the National Council for Stream Improvement and the Commit-
tee on Water Pollution, State of Wisconsin.
The reaeration procedure, still going on, consists of pumping air under
pressure through carborundum diffusers located in the head and tail races
of Pixley Dam. This location—6.3 miles from the pollutional source—
was selected as the point where dissolved oxygen approaches depletion.
Fig. 1. Drainage area of Flambeau river. North Fork shown in black.
Four summers of artificial reaeration study have shown the procedure to
be valuable in disposing of B.O.D. more rapidly, raising dissolved oxygen
levels and shortening the zone of critical conditions. That was the setting
under which a biological study was carried out during the summer of 1946.
The aims were three in number: (1) to determine the responses of
downstream biota to the presence of pollutants tributary to the river; (2)
to locate the stream level or levels of biological recovery, and (3) to deter-
mine if artificial reaeration visibly accelerates the biological recovery.
BIOTIC STREAM RESPONSES TO STREAM REAERATION 35
BIOLOGICAL CONSIDERATIONS
It is generally recognized that the living organisms in a polluted stream
are intimately concerned with many of the transformations that lead to
Fic. 2. Sources of pollutants, city of Park Falls. 1 and 2, lumber mills.
3, pulp and paper mill. 4, sewage treatment plant.
36 LIMNOLOGY, WATER SUPPLY AND WASTE DISPOSAL
sanitary recovery. At the same time, their linear distribution is influenced
by the intensity of pollution, while population magnitude is determined
by degree of suitability of the habitat. Some organisms find pollutional
conditions ideal for their livelihood and characterize these conditions by
their presence. They are sometimes called index organisms. Others are
inhibited by these same conditions, and their absence may be significant.
BIOTIC DEGREE OF POLLUTION
CHARACTER
POPULATION | gamma
DENSITY
ee
fics tUds coer RD
cn ee
SS
ANIMALS
_
BACTERIA . CG
EATERS
EATERS ;
cyte ae ea
EATERS
oat ea
SCAVENGERS re |
pobre ——— Ut
REQUIREMENTS
Fia. 3.
Such biotic responses are the basis for biological criteria of stream condi-
tion as summarized in Figure 3 modified from Hentschel.t Some of these
are as follows:
(a) Population density generally is in direct proportion to degree of
pollution except at the two extremes.
1 Hentschel, E. 1923. Abwasserbiologie. Handbuch der biologischen Arbeitsmethoden
by Emil Abderhalden. Sec. IX, Part 2, Book 1. Berlin-Vienna: Urban und Schwarzen-
berg.
BIOTIC STREAM RESPONSES TO STREAM REAERATION 37
(b) Variety of organisms is inversely proportional to the degree of
pollution.
(c) Scavenger populations may be tremendous in extreme pollution
and decrease rapidly with stream recovery.
(d) The more serious the condition of pollution, the less are the oxygen
requirements of the existing biota.
Fic. 4. Sampling stations, north fork of Flambeau river.
(e) Biotic responses to stream pollution are superimposed upon the
responses to natural stream conditions.
(f) The value of these criteria is jeopardized by the presence of toxic
types of trade wastes.
With this summary as a brief review, we are ready to examine the
sanitary and biotic status of the Flambeau River.
PROCEDURE AND Data
Sampling stations were selected at various stream intervals as shown
in Figure 4, beginning 7.1 miles above Park Falls and extending 39.1 miles
38 LIMNOLOGY, WATER SUPPLY AND WASTE DISPOSAL
downstream. All sampling was done by boat, since the river is not other-.
wise accessible. Samples were collected for data on B.O.D., apparent color,
physical character of stream bed, aerobic and anaerobic plate counts, B.
coli index, plankton and benthos. Not all of these data, although available,
will be reported here.
In the region under study, available bacterial foods are waste sulphite
liquor, wood fiber, domestic sewage and other organic substances of natural
origin. Graph 1 shows that the food supply, expressed as B.O.D., increases
abruptly as a result of the entry of waste sulphite liquor at level zero.
Bacterial oxidation plus a non-biological affinity of this trade waste for
5 t) 5 15 20 25 30
10
Alles
GraPH 1. 0 Five day biochemical oxygen demand ppm at 20°
C., ----- e————— Dissolved oxygen in ppm. Average for August 8, 9, 10.
oxygen reduces the supply to less than 1 ppm within 10 miles. A correla-
tive relationship will be shown between these environmental conditions,
high food and low oxygen, and the biotic density and distribution. It goes
without saying, of course, that other factors also are influential.
Twenty-four hour, 22° C aerobic plate counts are plotted as log of
the count per milliliter in Graph 2. Field conditions necessitated storage
of the samples just above the freezing point for 48 hours before plating,
so the dependability of the data is questionable. At the same time, they
do suggest an inhibitory influence of waste sulphite liquor. Anaerobic
counts tended to increase erratically downstream but are not considered
significant. As would be expected, the B. cols index reached a peak of
100,000 below Park Falls and gradually decreased to 1,000 twenty-seven
miles downstream.
BIOTIC STREAM RESPONSES TO STREAM REAERATION 39
Log. of Count
10 5 0 5 10 15 20 25 30
Milee
GrapH 2. Aerobic bacteria per milliliter plotted as logarithm of the count.
Two and one-half liter plankton samples were concentrated by means
of a continuous-flow centrifuge and analyzed in accordance with Standard
Methods of Water Analysis so that results could be expressed as popula-
tion per milliliter and as volumetric standard units.
The trend curve for total volume (Graph 3), expressed as volumetric
Midetrees
Plankton io
Volumetric Standard
Units Per Kl.
:
:
3
z
3
:
>
40 LIMNOLOGY, WATER SUPPLY AND WASTE DISPOSAL
standard units (8,000 cu. micra), shows an increasing quantity above Mill
Dam. Following introduction of mill wastes, the quantity drops within
1.5 miles from 190 to 95 volumetric standard units. Plankton again increase
in the quiescent water behind Pixley and Crowley Dams although never
reaching the volume peak above Mill Dam. The decrease from the 11 mile
level downstream shows the destructive and inhibitory influence of swift
and turbulent water. If quiescent water persisted downstream, it is possi-
ble that the plankton volume would increase beyond the peak at Mill Dam.
Volume of zooplankton is erratic but shows the same depression as
total plankton. As a group, they appear relatively scarce which may be
due, in part, to the difficulty of recognition in the preserved condition. These
Planktoa As
Volumetric Stenderd
Onite Per Fl.
Volumetric Standard Unite Por Ml,
10 5 0 5 10 15 30 25 39
Miles
GraPH 4.
totals, however, do not include immense populations of Carchestwm and
Vorticella attached to waving masses of Sphaerotilus natans along the
shore.
The main constituents of the phytoplankton show a trend of the same
pattern as that of total volume (Graph 4). The green and blue-green algae
and the diatoms all show a decline within 44 mile of the pollutant entry
point. Volume recovery is rapid from the 3 to 11 mile levels for both green
and blue-green algae, whereas the diatoms continue to decline to the 10
mile level and then increase only slightly.
The plankton data fail to locate a point or zone where recovery is
complete. It is concluded that the decreases in plankton in the down-
stream vicinity of Park Falls reflect the toxic influence of industrial efflu-
ents—perhaps from SO, in waste sulphite liquor. The following rising
BIOTIC STREAM RESPONSES TO STREAM REAERATION 41
volumes are interpreted as a positive response to increased food and food
material supplies made available through stream recovery processes.
Further decreases downstream apparently result from the swiftness and
turbulence of the stream.
While it would have been valuable to study the plankton for species
g
é
g
:
Organiens - log.
+s 16 5 is) 3 10 15 20 25 30
Miles
GrapH 5. Total Oligochaeta, log. (no./sq. ft. x 100)
that may be characteristic of waste sulphite liquor pollution, no attempt
could be made to do so. That information is lacking at the present time.
Samples of the bottom deposits and their organisms were collected
with the Eckman or Peterson dredges or with the square-foot sampler with
downstream net. Samples were examined for physical quality of the sub-
stratum and determination of quality and populations of bottom organisms.
Appreciable deposits of bark, chips or wood fiber were found as far as
6.1 miles downstream, and intermittent deposits of fiber 11 miles down-
stream.
Bottom organisms, as referred to here, are those restricted in their
habitat to a position on the surface of, or imbedded in, the accumulated
deposits or natural bed of the stream. They obtain their food from the
supernatant medium in which they are bathed or feed as they burrow
through or creep over the beds of deposited substances. Inhabitants of
such substrata in pollutional areas must be able to tolerate low oxygen
supply and toxic products of anaerobic processes. Some of the larger
inhabitants are nematodes, flatworms, annelids, crustaceans, molluscs and
insect larvae.
Since organisms vary in their powers of pollutional tolerance, it is
to be expected that some species will find suitable conditions for existence
42 LIMNOLOGY, WATER SUPPLY AND WASTE DISPOSAL
at points where natural recovery has not yet progressed sufficiently for the
livelihood of others. For this reason population peaks of various species
will be arranged in linear order downstream. Certain species, though often
occurring in clean water, are able to tolerate and frequently thrive under
severe pollutional conditions. Notable of these are tubificid worms and
chironomid larvae. Certain naiad worms, sphaeriid mussels, some snails
and the Isopod, Asellus communis, thrive in regions of low and improving
oxygen content. The presence of appreciable numbers of these, especially
in the absence of less tolerant species, is evidence of serious pollution.
Some of these biotic relationships and responses to pollution will be shown
in the following graphs.
Total Oligochaete population, and especially the tubificid worms
(Graph 5), shows a positive response to the presence of pollutants. They
are notorious for this type of response, and their population trend follows
the B.O.D. trend quite closely. Even hard bottom populations, which are
normally low, increase considerably downstream.
is
S .
gS
Lt
‘
ral
-
¢
&
:
4
Orgenicma - Log.
10 3 te) 3 15 20 25 30
Miles
GrapH 6. Total Chironomidae, log. (no./sq. ft. x 100)
Chironomid larvae (Graph 6) are absent from the immediate down-
stream vicinity of Park Falls but respond quickly to pollutional condi-
tions by producing an appreciable population within 2 miles. They reach a
population peak at about 11 miles and then decrease gradually downstream.
The distribution of all other insect larvae (Graph 7) is in contrast
to the Chironomidae. A substantial population of these clean water forms
was present above Park Falls but dropped to zero following the introduc-
tion of pulp and paper mill effluents. The bottom was devoid of insect
larvae, other than chironomids, for a downstream distance of 8.6 miles,
and some habitats were still unsuitable beyond that point.
BIOTIC STREAM RESPONSES TO STREAM REAERATION 43
Organisms - Lag. (no./eq.ft. = 100)
10 5 0 3 10
Hiles
Grapu 7. All insect larvae minus Chironomidae, log. (no./sq. ft. x 100)
35 25 30
The snail populations (Graph 8) consisted of 4 different species with
Campeloma integrum the dominant one. Three of them are pulmonates
which may breathe air by means of a lung and therefore are not dependent
upon dissolved oxygen values of the stream. For this reason, their distri-
bution is governed mainly by available food, suitable substratum and con-
g
fn
é
a
g
3
q
&
GrapH 8. Total snails, log. (no./sq. ft. x 100)
44 LIMNOLOGY, WATER SUPPLY AND WASTE DISPOSAL
@ Soft Botton
O fterd Botton
Orgenioms - Log. (no./eq.ft, 1 100)
10 3 ° 5 10 45 20 a5 30
Wiles
GraPH 9. Total Sphaeriidae, log. (no./sq. ft. x 100)
centration of toxicants. While they apparently resist high concentrations
of waste sulphite liquor, they do not inhabit the zone immediately below
the industrial sewer outlet. Within 3 miles, they reappear in concentrated
population and persist beyond the 32 mile station.
@ Soft Bottom
O Hard Bottca
g
:
i
g
i
3
E
10 5 °o 5 15 20 25 30
10
Miles
GraPH 10. Population of Asellus, log. (no./sq. ft. x 100)
BIOTIC STREAM RESPONSES TO STREAM REAERATION 45
The sphaeriid mussel, Sphaertum rhomboideum, also responds posi-
tively to intense conditions of pollution (Graph 9). Although immediately
inhibited by trade waste, the rapid population increase downstream resem-
bles that of the Oligochaetes.
The sow-bug, Asellus, is recognized as an indicator of mild or improv-
ing conditions. They reach their population peak near the 15 mile level
(Graph 10) and are infrequent beyond 25 miles.
Population peaks of the prominent bottom organisms have the follow-
ing linear order: Oligochaeta—3.2 miles, Sphaeriidae—7.7 miles, Chironomi-
dae—11, Asellus—15, snails—22, and various insects as a group—26 miles.
@ Soft Bottom -
\Popalation
O Bard Botton °
& Soft Bottom »
\tumber of Species
& Hard Bottea
Population - Log. (no./oq.ft. x 100)
10 5 ° 5 10 15 20 25 30
Hiles
GraPH 11. Relationship of populations and numbers of species.
The trend curve of total bottom population (Graph 11) is in contrast
to station variety expressed as number of species. It will be noted that
variety begins to decrease above the zero level. This appears to be due,
at least in part, to decreased velocity above Mill Dam and to the presence
of bark and chips accumulated on the bottom. Variety is decreased further
with the entry of trade wastes with only 3 species found in the distance
of 1.8 miles to Lower Dam. Variety increases somewhat below this point.
On soft bottom, the pre-pollutional variety is not regained at any down-
stream level examined, but on hard bottom variety is normal between
the 10 and 15 mile level.
While there is considerable station-for-station fluctuation in total popu-
lation, the trend is for a striking population peak near the 9 mile level.
The following progressive decrease apparently results from declining food
supply and changing physical conditions.
46
LIMNOLOGY, WATER SUPPLY AND WASTE DISPOSAL
DISSOLVED
OXYGEN
BACTERIA
PLANKTON
BENTHIC
POPULATION
VARIETY
Fic. 5. Diagrammatic summary of data.
BIOTIC STREAM RESPONSES TO STREAM REAERATION 47
CoNCLUSIONS
The pertinent data on stream condition are diagrammatically summar-
ized in Figure 5. Without question, there are definite biotic responses to
industrial pollution and the environmental conditions that result. Decreases
in population of bacteria and plankton and abrupt loss in variety of bottom
organisms below the industrial sewer suggest the presence of a toxic ingredi-
ent. Gas production and the rising of bottom fiber mats occur in the
region of oxygen depression. This region is unsuitable for many kinds of
organisms, but the persistent ones thrive, and scavengers are numerous.
Fic. 6. Stream zones, north fork of Flambeau river.
Abrupt improvement of the biological picture below the site of arti-
ficial reaeration was not apparent. At the same time, improvement in
the recovery zone may be accelerated so that a normal, clean water biota
extends farther upstream.
The available data show that conditions for biotic existence below the
20 mile level are similar to those above Park Falls. These are the zones
of clean water as shown in Figure 6. Thirteen miles of stream are seri-
ously affected by pollution and have little recreational or other value. For
2.5 miles below Park Falls, in the zone of degradation, dissolved oxygen
decreases to 40 per cent saturation and inhibitory substances are present.
Below this zone oxygen conditions are poorest for aquatic life. Dissolved
48 LIMNOLOGY, WATER SUPPLY AND WASTE DISPOSAL
oxygen approaches or reaches zero in the zone of active decomposition and
then slowly climbs to a level sufficient for a variety of organisms. Improve-
ment continues in the recovery zone with normal biotic populations at the
20-mile level.
Biotic responses to stream pollution lead to the intense biochemical
activities that assist in sanitary recovery. Bad as it may seem, localized
stream defilement is a necessary part of the process. Only by this sacrifice
are the recreational downstream areas preserved.
SUMMARY
During the summer months, since 1944, diffused air has been pumped
into the North Fork of the Flambeau River near Park Falls, Wisconsin,
in an attempt to alleviate the serious conditions resulting from sulphite
pulp and paper mill pollution. While four years of study have shown bene-
fits from the artificial reaeration procedure, biotic responses to pollution
under these conditions were unknown.
Investigation has shown no abrupt biological improvement near the
artificial reaeration site, but improvement in the downstream recovery
zone is accelerated. The introduction of these industrial pollutants has an
immediate toxic influence upon most organisms and alters the biological
picture for a distance of 20 stream miles. In this region the societies of
organisms increase, reach a population peak, and decrease in linear order
as their biochemical activities change the degree and character of pollu-
tion. Action upon the pollutants in the 20-mile zone produces local critical
conditions but, in so doing, protects downstream recreational areas.
A STUDY OF KRAFT PULPING WASTES IN RELATION
TO THE AQUATIC ENVIRONMENT
WILLIS M. VAN HORN
THE INSTITUTE OF PAPER CHEMISTRY, APPLETON, WIS.
INTRODUCTION
OF THE several methods for the manufacture of chemical wood pulp,
the kraft process now occupies a major position in the industry. Tonnage-
wise, the amount of this type of pulp produced in the United States exceeds
that produced by the sulphite and soda processes combined. In the pres-
ent discussion, it is well to distinguish clearly between the kraft and the
sulphite processes.
In the sulphite process, the liquor used for digesting the wood is an
aqueous solution of sulphurous acid in which lime, or some other base, has
been dissolved; the final result is, therefore, a solution of a bisulphite of
the base containing an excess of sulphurous acid. The nature of this
liquor, where calcium is used as the base, as well as the mechanics of the
sulphite process, makes it economically unfeasible to recover the spent
liquor; it is accordingly wasted to the river and is commonly known as
sulphite waste liquor.
The kraft process, on the other hand, is an alkaline process. The
principal constituents of the cooking liquor are sodium hydroxide and
sodium sulphide, the latter comprising up to 45% of the total. From
the present point of view, the important aspect of the kraft process is that
the spent liquor is recovered, for the most part, by a process involving
evaporation and combustion. In this treatment, the chemicals are recovered
and heat energy is generated as well.
In order to understand the problem at hand, it is desirable to con-
sider briefly the principal features of the kraft pulping process.
The wood is carefully prepared and cut into small chips, after which
it is introduced into large receptacles called digesters. The cooking liquor
is added and the digester securely closed. Heat is then gradually applied
and the cooking process is started.
The cooking cycle of any type of chemical pulp production consists
of three phases: a period during which the liquor is penetrating the chips
and the internal pressure is being brought up to cooking level, a full pres-
sure period during which the wood is actually being cooked, and a gassing-
down period during which the pressure in the digester is lowered slowly to
the point where the pulp can be blown therefrom.
At the start of a cook, there is a considerable amount of air in the
digester which must be removed before the start of the second phase.
49
50 LIMNOLOGY, WATER SUPPLY AND WASTE DISPOSAL
After the digester is brought up to pressure, therefore, it is relieved; that is,
the air and other accumulated gases are permitted to escape. This initial
“blowdown,” as it is called, is usually condensed and its condensate is one
type of waste from a kraft mill. Similarly, at the completion of the second,
or cooking, phase of the operation the digester is again relieved, these
“final blowdown” gases are condensed, and the condensate becomes waste.
When the digesters are blown (or emptied) at the conclusion of the
cook, the pulp is blown to a pit and the spent liquor (or black liquor) is
collected and sent to the recovery plant. The pulp is washed by a series
of waste waters used in washing previous batches of pulp. The black liquor
concentration of these waste waters is increased with every batch of pulp
washed and, eventually, when the concentration is high enough, they are
sent to the recovery plant along with the concentrated black liquor. In
the final washing processes, however, the wash waters may be so dilute
that their chemicals cannot be recovered economically; for that reason,
they may be sent to the sewer.
The spent black liquor and the concentrated wash waters are sub-
jected to evaporation under a vacuum to a consistency of approximately
50% solids. The vacuum is produced by a barometric leg and in its efflu-
ent may be found in solution some of the noncondensable gases from the
process of black liquor evaporation. This effluent is a waste material.
The concentrated black liquor containing most of the nonfibrous por-
tion of the original wood, as well as the spent chemicals, is then burned in
recovery furnaces; the chemicals and heat energy are thus recovered.
When the black liquor from the blow pits is sent to the recovery plants,
it is usually stored in large receptacles for varying periods. As the material
stands in these tanks, a thick foamy material, called sulphate soap, rises
to its surface. Actually, it is composed of the sodium salts of resin and
fatty acids which were in the wood. Currently, this soap is recovered and
sold, but small amounts of it may be found in the dilute wash water. It
is interesting to note that, although eastern and southern woods have a
relatively high resin and fatty acid content, the woods of the Pacific North-
west contain very little. For that reason, the kraft mills in the northwest
are not ordinarily faced with a serious soap problem.
In summary, it can be stated that the major stream polluting products
from the normal operation of a kraft mill are: (a) initial blowdown con-
densate, (b) final blowdown condensate, (c) evaporator condensate, and
(d) soaps and other material in the weak wash waters.
It is the purpose of this paper to describe the possible effect of these
wastes on the aquatic environment and to consider measures which may
be employed to prevent their reaching the stream.
Krart WASTES AND THE STREAM E\NVIRONMENT
The relief gases referred to above have been studied rather widely in
Sweden and Germany. It was demonstrated by Klason and Segerfelt
(1911) that up to 1000 gm of mercaptans may be produced per ton of wood
KRAFT PULPING WASTES AND AQUATIC ENVIRONMENT 51
pulped. It was noted that pine yielded approximately twice as much
mercaptans as spruce. Falk (1909) analyzed the condensates from the
kraft cooking process and found that the oily and aqueous portions con-
tained the following per ton of wood pulped (Table I):
TABLE I
ANALYSIS OF Krarr CooKING CONDENSATES
In Oil Portion, In Aqueous Portion,
kg kg
WieK Cap tansy) st MOS et ave li 0.062 0.06
Dimethyl! sulphide ............... 0.927 0.17
Dimethyl! disulphide ............. 0.103 0.05
BMT DETIGIME! pee sa a Ue ea 8.487 0.92
Methylialcoholieccrnechaeeeaeeee. 5.00
PAUMIMO MTA Goes ey ae ae au da 0.18
The black liquor which is drained from the pulp and the small amount
of which may find its way to the sewer, has been analyzed by Klason and
Segerfelt (1911). According to them, its organic matter consists of 54.3%
lignin, 2.5% fatty and resin acids, 3.7% formic acid, 5.2% acetic acid,
and 30.3% lactonic acids. In addition, Cirves (1930) made the analyses
shown in Table II.
TABLE II
Buack Liquor ANALYSIS
Chemical Amount,
g/l
Sodium! bicarbonate ce ne oe ee eee oer cote 14.78
Sodiummhydroxidemaas emcee ses eitctletels 1.43
Sodiumsulolird ele ese vaetrcilevereveclalstsiersierslevers ce 3.01
Sodmmeaswlpbatenecwran cies se aciceei cots arora: 14.70
Sodiumypsulp hired yee aie cee cieis miele) sveievenearslenere ts 6.64
Sodiumpiehloridey airs cia ois Sosales sre everest okers! « 0.88
Sodium! thiosulphatel auece an seaee cece meeeiae 3.98
Sodium salts of organic acids (soaps) .......... 14.52
Orgamicvacvas |e we ewe ees eyes RLM eur steals 92.49
TAYE 5) UL EU 8 Tae Up RG Hn a EN ee 846.05
It becomes apparent that many of the materials listed might have a
serious effect on the aquatic environment if present in sufficient quantities.
That this is the case has been demonstrated by several workers. Ebeling
(1931) found that the greatest poisonous action of the nonsulphur com-
pounds was exhibited by the sodium salts of resin and fatty acids. Hag-
man (1936) established the minimum lethal concentration of these acids
to fish at 2 ppm. He also pointed out that the sulphur components
52 LIMNOLOGY, WATER SUPPLY AND WASTE DISPOSAL
(mercaptans, sulphides) of these wastes may be toxic in concentrations
as low as 0.5 ppm. Hagman’s results have been substantiated by Berg-
stro6m and Vallin (1937), who made a special study of the relief and evapor-
ator condensates described above.
Several investigators have studied this problem in our own country.
Cole (1935) investigated the effects of whole black liquor on perch, blue-
gills, large-mouth black bass, and rock bass, and found that it would kill
these species in concentrations above 5000 ppm. Extrom and Farner (1943),
working on the premises of a typical kraft mill located on a medium-sized
stream, were able to calculate the concentration, under ordinary circum-
stances, of the wastes in question in the stream. Using these concentrations
in continuous flow experimental aquaria, they determined that bass, blue-
gills, and sunfish were not adversely affected by such concentrations of
black liquor and blowdown condensates. They found, however, that some
of the chemicals listed above, particularly the sulphur compounds and the
soaps, were present in the mill sewer in concentrations high enough to kill
fish. They concluded, therefore, that, if there was stream volume discharge
to adequately dilute the wastes, the stream environment would not be
adversely affected, but that it was possible (particularly at periods of low
stream flow) for the wastes to be present in dangerous concentrations.
Generally speaking, therefore, it can be concluded that, of the com-
ponents found in a typical kraft pulp mill waste, the sulphur compounds
(particularly the sulphides and the mercaptans) and the resin and fatty
acids (and their sodium salts) are, potentially, the most dangerous to the
aquatic environment.
REMEDIAL MEASURES
Studies on toxic effect of kraft pulp mill wastes on stream environments
have progressed to the point where a well-directed effort can be made to
materially abate such pollution.
One of the most effective methods of abating kraft pulp mill pollution
embodies simply efficient and careful operation of the plant. It has been
pointed out that, normally, most of the spent liquor is recovered; indeed,
the economic feasibility of the kraft process depends on adequate chemical :
and heat recovery. If the plant is efficiently operated at all times, the
loss to the sewer of harmful chemicals can be greatly reduced. However,
because of inadequately trained or careless operating personnel, or because
of unavoidable mechanical difficulties, it is not always possible to effect
top-rate performance. For that reason, it is desirable to examine additional
methods of abatement. For purposes of discussion, this can be done most
satisfactorily by considering each waste element separately.
The soap problem. No well-operated mill permits the escape of much
of the soap material to the sewer. Formerly, it was burned along with
the rest of the black liquor and its chemicals and heat values were recov-
ered. More recently, however, its chief constituent, tall oil, has been sepa-
rated and marketed in considerable quantities. The fat scarcity in recent
KRAFT PULPING WASTES AND AQUATIC ENVIRONMENT 53
years has made its recovery especially profitable and it is expected that,
even after the scarcity ends, there will be a ready market for it. From
the stream pollution abatement point of view, the recovery of tall oil
removes essentially all the fatty and resin acids from the wastes.
The digester relief condensates. It was noted above that these wastes
contained considerable amounts of turpentine. Formerly, most of this
material was wasted. In recent years, however, the economic advantage
of its recovery has become so apparent to mill operators that most mills
recover it and find a ready market for it.
In addition to the turpentine, the digester relief condensates contain
sulphur compounds; in the present case, those of primary interest are the
sulphides and mercaptans. The amounts of these materials in these wastes,
which may be relatively large from the point of view of stream pollution,
are too small to be recovered to economic advantage. For that reason, not
a great deal of attention has been directed to their removal from the wastes.
The problem, therefore, is to provide a method by which these wastes
may either be removed or neutralized before they are passed to the stream.
One of the complicating factors in removing the mercaptans and sul-
phides lies in their inherent odor characteristics. Anyone who has spent
much time around a kraft mill knows that there is, ordinarily, a typical
smell associated with the process. Many people think that this smell is
unpleasant, not to say foul, and there is some justification for this opinion.
The basic source of this smell is in the presence of the very substances
under consideration. In considering ways and means of eliminating these
compounds from the stream, attention must be given, therefore, to the
problem of air pollution as well.
In conducting experiments on the toxicity of kraft mill waste com-
ponents to fish and other aquatic organisms, it was discovered that the
toxic properties of any given concentration may be significantly reduced
if a finely divided stream of air is passed through the solution. It is unlikely
that the phenomenon is caused by any other means than the action of the
air-flushing or washing the materials from the water, although it is possi-
ble that some oxidation occurs. This observation suggests the possibility
that the wastes in question could be detoxified simply by subjecting them
to a process of thorough aeration and/or agitation.
The easiest and most economical method of achieving this end is the
one that has been and is now employed—namely, the use of the receiving
stream. In normal circumstances, if adequate volumes of water are avail-
able for dilution, the stream will absorb or dissipate these sulphur com-
pounds rapidly enough so that the danger to aquatic fauna is eliminated.
The possibility always exists, however, that, in periods of low flow and
high production, the absorbing capacity of the stream will be taxed beyond
a safe limit and, under those conditions, the need for some other method
of treatment becomes apparent.
The problem is complicated by the relatively large amounts of water
in which the sulphur compounds may be carried. A treatment process
54 LIMNOLOGY, WATER SUPPLY AND WASTE DISPOSAL
must take into account these water volumes with the resulting complica-
tions relating to economics.
Various attempts have been made to impound these wastes in reser-
voirs, sometimes for extended periods. For example, Crawford (1946)
was able to provide adequate stream protection by storing in a lagoon
(for periods up to 90 days) the more concentrated wastes from a typical
kraft mill. The objective of this installation was to provide storage space
during periods of low water for subsequent release when the river was high.
The work demonstrated that, during the time the wastes were impounded,
their pollutional properties were greatly reduced. A somewhat similar
installation, described by Gehm (1947), has been made in Texas with satis-
factory results.
The construction and successful operation of lagoons involve a number
of requirements not always available on a pulp mill premises. For example,
in order to operate successfully, the contents of a lagoon must be held at
a level higher than that of the receiving body of water. In mills located
on or near tide water, this primary requirement cannot be met without
great capital outlay. Furthermore, lagoons, over a sustained period of
operation, will fill with solids and must be dredged or otherwise cleared.
Depending on the type of operation, this might have to be done often
enough to make lagooning operations unfeasible.
Several studies have been made to remove the sulphur compounds
from kraft wastes of kraft mills by special processes. Bergstrém and
Trobeck (1945) have suggested that water pollution can be abated by
removing the sulphur compounds in wooden absorption towers. The
towers contain fillers of a type to afford a maximum absorbing surface.
The wastes are passed downward over the filler and waste stack gases are
forced upwards through the tower. It is claimed that this process will
remove most of the sulphides contained in the condensates. If this type
of installation can be made to work, it will reduce considerably the amount
of sulphides and other sulphur compounds which ordinarily pass to the
stream. One objection, however, becomes apparent. The apparatus may
prevent the sulphur compounds from passing to the stream and pass them
to the air instead. This would result in an air pollution problem which
might be considered worse than possible effects on the stream.
Actually, the feasibility of the Bergstrom and Trobeck development
remains to be demonstrated in our country.
SUMMARY
Under normal circumstances, kraft. pulp mill operation depends, for
its economic feasibility, on the recovery and utilization of the components
of its spent liquor. If the mill is well operated and adequate stream dis-
charge is available, the effluent from the mill should not cause a serious
stream pollution problem. Certain sulphur components in the wastes,
particularly those in the condensed blowdown and evaporator condensates,
KRAFT PULPING WASTES AND AQUATIC ENVIRONMENT 35
have been shown to be toxic to fish and other aquatic fauna. Methods of
preventing these components from reaching the stream are discussed.
REFERENCES CITED
Berostrom, H. anp Troseck, K. G. 1945. The removal of malodorous substances from
the condensate of digesters and diffusers by means of special towers. Svenska Pap-
perstidn., 48, no. 10: 246.
Bercstrom, H. anv VaLLin, S. 1937. The contamination of water by the waste liquors
of sulphate pulp mills. Kungl. Lantbruksstyrelsens Medd. Statens undersoknings-
och férsdksanstalt for sotwattensfisket. No. 13.
Cirves, F. J. 1930. General analysis of black liquor. Paper Trade Jour., 91, no. 19: 55.
Corz, A. E. 1935. Water pollution studies in Wisconsin. Effects of industrial (pulp and
paper mill) wastes on fish. Sewage Works Jour., 7, no. 2: 280.
Crawrorp, 8. C. 1946. Ponding of sulphate mill wastes. Paper Mill News 69, no. 36: 12,
14, 17-18.
Exsetine, G. 1931. Recent results of the chemical investigation of the effect of waste
waters from cellulose plants on fish. Vom Wasser, 5: 192-200; C. A. 26: 2262.
Exrrom, J. A. aNp Farner, D. S. 1943. Effect of sulphate mill wastes on fish life. Paper
Trade Jour., 117, no. 5: 27-32.
Faux, H. 1909. By-products in the manufacture of soda pulp. Papier Fabrik., 7: 469-72.
Geum, H. W. 1947. The industrial waste problem. III. Recent developments in pulp
and paper waste treatment and research. Sewage Works Jour., 5: 827.
Haocman, N. 1936. Resin acid and fish mortality. Finnish Paper Timber Jour., 18: 32-34,
36-38.
Kuason, P. anp SecerFett, B. 1911. Ueber den chemischen Verlauf der Herstellung von
Sulfatzellulose. Papier Fabrik., 9: 1093-99.
PLANKTON AS RELATED TO NUISANCE
CONDITIONS IN SURFACE WATER
By JAMES B. LACKEY
THE BLAKISTON COMPANY, PHILADELPHIA, PA.
Man Has never been able to do without water very long. Preferably
clear, cool, virtually tasteless and odorless; not like the “arf-a-pint o’water
—green” that crawled and stunk, which Gunga Din gave the British
Tommy. But, like the Tommy, we are grateful for even that kind if no
other is available. Gunga Din’s water must have been taken from a pool
in full bloom, well exemplifying those nuisances which blooms can cause.
For they all too frequently turn surface waters into nauseous soups of
some green, brown or red shades that truly stink. Hence the reason for
an article on “Plankton as Related to Nuisance Conditions in Surface
Water.”
Plankton may be defined loosely as suspended aquatic small plants
and animals. A bloom is an unusually large number of plankters, usually
one or a few species, per unit of the first few centimeters of surface water.
An arbitrary definition (Sawyer, Lackey and Lenz 1944) has set 500 indi-
viduals per ml as constituting a bloom. Extremely small algae, such as
Chlorella or Gleocapsa, are not crowded at such an aggregation, but
Pandorina would be. There are, of course, plankters of which a single indi-
vidual exceeds 1 mm in diameter, or 1 ml in volume.
Nuisances due to peak occurrences of these organisms are many. A
partial list includes: Nauseous tastes and odors in drinking water;
lakeshore decay with odor and debris; interference with bathing, boating
and fishing; killing of fish; prevention of stock watering; shortening of filter
runs in water purification plants; effects on industrial water use, such
as growths in cooling systems; poisoning of waterfowl, stock, and possibly
man; poisoning of mussels; secondary fish depletion because copper sulfate
has been used to control blooms; secondary increases in mosquito nuisances
by increasing larval food.
This list could be extended by specific instances. For example, during
the war a sewage plant effluent was turned into an otherwise dry stream
bed near a small Texas town. The effluent, highly purified, produced heavy
growth of filamentous algae which, in turn, produced pooling. In the stag-
nant waters, mosquitoes—some of them anophelines—bred abundantly.
This is a highly specialized case and it might be questioned, academically,
that either surface waters or plankton were concerned. The complaints
of fishermen concerning the vast mats of filamentous algae in some Wis-
consin lakes are similar, but there is no doubt that these algae can be
56
PLANKTON AND NUISANCE CONDITIONS IN SURFACE WATER o7
planktonic or that they interfere with both bathing and boating as effec-
tively as a bloom of Anabaena or Microcystis.
Tastes and odors in drinking water are only too familiar to water
plant operators, as are shortened filter runs. Almost any group of algae
may cause them, but blue-greens, brown flagellates (such as Synura or
Uroglenopsis) and diatoms are the chief offenders. Increased operating
costs accrue in such cases, but equally bad is the loss of revenue when
summer cottagers leave because an onshore wind piles their beach with a
loathsome mass of decaying algae. And according to newspaper and other
reports (Staff, Univ. Miami Marine Laboratory 1947) the recent red
waters near the Florida shores were simply a huge bloom of dinoflagellates
which not only hurt commercial fishing, but also left fish carcasses along
shore in such numbers as to cause vacationists to leave.
It has been observed frequently that stock will not drink while a
heavy red bloom of Euglena sanguinea is present. Stock deaths have been
attributed to poisonous blooms in the U. 8. (Fitch et al. 1934), Africa
and Australia; and in 1946 (Hervey) waterfowl deaths in Utah were
ascribed to huge numbers of dinoflagellates. Mussel poisoning along the
Pacifie Coast is familiar, and its appearance along the Atlantic Coast should
be carefully watched for, as we increase the species of shellfish we eat.
There are numerous instances of enteric diseases in man, apparently water-
borne, and not satisfactorily accounted for, but which seem to travel down-
stream—in one instance, at least, paralleling the downstream travel of an
algal bloom.
THE NATURE, OCCURRENCE AND CAUSES OF THESE BLOOMS
Blooms are typical of shallow lakes in the late summer, but may occur
in almost any body of water at any time of the year. They are not gen-
erally noticed by laymen until surface waters are obviously discolored.
Blue-green algae are perhaps the most common producers of blooms in
stagnant water, but in streams a much wider variety of organisms is en-
countered in bloom densities. Colors range from a rather pale yellow-
green or blue-green, such as caused by Anabaena in Prospect Park lake in
Brooklyn, in 1924, to yellow (Gleotrichia, Mendota, 1942), brown (Peridi-
nium, Chillicothe, Ohio, 1936), or red, Euglena sanguinea, North Alabama,
1935; Azolla, North Mississippi, 1940). Table I shows the organism groups
which reached bloom proportions (i.e., 500 organisms per ml of raw water)
(Lackey 1943-44), a total of 509 times during a two years’ survey of 16
southeastern Wisconsin lakes and three rivers in 1942-43. It should be
clearly understood that not all this impressive list of 509 blooms were of
the nuisance type.
There were actually more blooms, 509, than the 478 samplings. Evi-
dently high populations in Monona, Waubesa, Kegonsa, Wingra, Geneva,
and the three rivers were mixtures of two or more species and their normal
biota was rich and varied. Except Geneva, all had nuisance conditions.
Blooms in Geneva were due largely to very small organisms; the layman
58 LIMNOLOGY, WATER SUPPLY AND WASTE DISPOSAL
would never have noticed them. Mendota had one extremely bad condi-
tion, a particularly nauseous population of Gleotrichia.
Table I also indicates to what group these abundant organisms be-
longed. The only animal blooms were flagellates and ciliates although no
account of copepod populations was taken. Animals were not a nuisance.
TABLE I
Tue NumBer, COMPOSITION AND OccURRENCE OF BLooMs DurinG a Two-Year SURVEY
Gay
nm 2) [.>) =
= ian) eh ne as é
S) 3 a) ry ry ae
3 ia) =| = SS 5 wn S
a o ic a a o ap 3
be fe E SN een iS ina rE ia)
2 = o iS) = 3 zB 5 =| a s
B22) 28 2s) bl b |) Ss eee
Z a Q Q Q 1) 'S) > o) aie
Mendota 59 22 2 10 3 1
Monona 64 86 10 28 15 i 13
Waubesa 64 | 112 12 52 1 18 16 1 1
Kegonsa 63 80 2 29 20 1 18 2
Wingra 52 91 15 34 6 12 2 3
Como 10 7 4 3
Delevan 13 5 2 2
Geneva 11 13 3 7 1
La Belle 13
Lauderdale 13 1 1
Nagawicka 13 1 1
Nemahbin 13 2 1 1
Oconomowoc 14 4 4
Okauchee 13 1 1
Pewaukee 12 6 1 4 1
Rock Lake 12 5 1 2 2
Crawfish River 10 20 3 12 1 2
Koshkenong River} 13 33 9 11 5 2 2
Rock River 14 20 2 9 1 1
Totals 478 | 509 68 | 205 1 73 26 54 7 1
PLANKTON AND NUISANCE CONDITIONS IN SURFACE WATER 59
There were only 68 high occurrences of blue-green algae, generally the
most troublesome group, while diatoms, rarely obnoxious, were high 205
times. Obviously the table indicates that any of the groups of algae may
pass bloom proportions if conditions are right. No chronology is shown
here, but these peak populations occurred at any time; two very dense
swarms of Volvocales (Chlamydomonas and Diplostauron) occurred under
ice cover in Kegonsa. Diatom abundance was noted through the year and
in these lakes was due most frequently to small naviculoid forms and to
bandbox forms, such as Cyclotella: small, and not productive of color in
surface waters. In rivers, forms like Synedra occur in huge swarms and
overnight may make their presence felt in the filter runs. In Lake Michi-
gan Tabellaria and Asterionella have been conspicuous. Diatoms, however,
are rarely troublesome except to water supplies.
Dinoflagellates, while frequent in these Wisconsin lakes, were not a
nuisance. In oceanic waters their blooming is well known, and their oily
inclusions could be very troublesome in water supplies. Cryptophyceae
have not been reported as troublesome, but because they sometimes occur
in huge numbers, may contribute to tastes and odors. Centrifuging a virtu-
ally pure population of Cryptomonas produced almost no whole cells; but
the olive-green slime adherent to the centrifuge walls was highly offensive
in odor, and these organisms readily disintegrate on sand filters. They
tend to be especially abundant in rivers. Chrysophyceae seem to occur in
winter and spring or late fall. In this survey they were not troublesome,
but are notorious to water works men. They are especially characteristic
of non-caleareous waters; many genera, abundant along the Atlantic sea-
board or in Lake Michigan, are totally lacking in the Ohio Valley. Volvo-
cales probably rank next to blue-green algae as obvious trouble makers,
and together with other green flagellates, such as Euglena, are often con-
spicuous in waters whose organic content is above normal. But they do
not occur in such numbers as to form windrows on the beaches.
Other bloom-forming organisms such as Azolla, Lemna or small arthro-
pod water fleas are either rarely troublesome or do not belong to the
plankton.
The causes of blooms have long been debated. Highly special or local
causes may occur at times, but there seems little reasonable doubt at
present that one or more optimal conditions—light, temperature, pH, food
—produce them, and perhaps the most compelling of these is the nutrient
content of the environment. Many laboratory studies have indicated that
nitrogen and phosphorus relationships are perhaps the most critical. Trace
elements should be sufficiently abundant in natural waters from large drain-
age areas to supply the infinitesimal amounts presumably needed. But
nitrogen and phosphorus demands are comparatively large. Drainage areas
may supply these demands from four sources: Original, virgin land; agri-
cultural (fertilized) land; sewage; trade wastes.
Table II shows inorganic nitrogen relationships in two small Ohio
creeks draining small areas; these determinations were made when light
60 LIMNOLOGY, WATER SUPPLY AND WASTE DISPOSAL
TABLE II
InorcANic NirroGEN—OrGANISM RELATIONSHIPS IN Two SMALL OHIO CREEKS
Station Nitrates Nitrites Number of Number of
p.p.m. p.p.m. species organisms
Lytle Creek
1 10 01 40 826
2 44 02 32 1,629
3 80 08 31 954.
4 08 01— 22 1,097
5 08 01— 39 25,189
Crown Creek 04. 01— 40 313
and temperature were optimal for many species, and stream flows average.
Both creeks showed small amounts of nitrites and nitrates but admission
of a sewage effluent below Station 2 in Lytle Creek changed that condition.
Station 1 was above the town, some of whose street drainage was respon-
sible for the increase at Station 2. Within about four miles (Station 5)
nitrates had decreased to normal, nitrites had dropped nine-tenths, and
organisms had multiplied twenty-five times; there was a dense bloom of
Euglena, Chlamydomonas and Phacotus.
Table III shows that temperature may keep populations low even if
sufficient nitrogen and phosphorus are present; but rising temperatures
result in a sharp increase of organisms, until the available nutrients are
lowered past a critical point, when organisms also decrease sharply. This
table does not indicate that most of the organisms in Lake Delevan in
January and February were quite small, whereas in April and May the
organisms were much larger and of different species.
TABLE III
NitTrRoGEN-PHOSPHORUS ORGANISM RELATIONS IN LAKE DELEVAN
Inorganic Inorganic
Date nitrogen phosphorus Number of Number of
ta alsiny fra Soe species organisms
January 24 ....... 0.87 0.07 21 819
February 29 ...... 59 35 26 361
Aral eS cen ane se 36 025 32 996
May Oricon ror nss .o2 03 34 1,826
JUNE 6. osc se he 22 01 24 184
Julyial Wee ce cian 09 01 33 223
Detailed studies of these Wisconsin lakes gave the following average
inorganic nitrogen and phosphorus values over a year’s cycle, shown in
columns one and two of Table IV and averaged from analyses of samples
collected during one year.
PLANKTON AND NUISANCE CONDITIONS IN SURFACE WATER 61
TABLE IV
Inorcanic NirroGEN AND PHOSPHORUS IN WISCONSIN LAKES
Lake Inorganic N, ppm Inorganic P, ppm No. blooms
Mendota ene -ensen. 17 .018 22
Monona ........... eet 23 041 86
Wiaubesa ....65...../6. 79 38 112
WEF ONSA! ee)e her en slee 35 33 80
VAI Dt y eres See SG 26 012 91
Koshkenong .......... 39 019 7
Delevans ies celeb ae ol 023 5
Geneva o.oo dec. 10 01— 13
WOMOR ARS ises csc as 14 01— 0
Lauderdale ........... 13 01— 1
Rewaukee ele wee 15 01— 1
INaeawicka: iscsi oo): BY 016 2
Upper Nehmabin ..... 24 013 4
Okauchee~ 2232522505 13 01— 1
Oconomowoc ......... 12 ‘ol 1
WacwWavbelle: s2202 se. 19 01— 6
ROC Kapa Mone aes a 10 01— 5
On the basis of this and other data Sawyer reasons: “In general, it may
be concluded that lakes showing average annual concentrations of inor-
ganic nitrogen and phosphorus in excess of 0.30 and .015 ppm, respectively,
will produce frequent ‘nuisance blooms.’” Table IV generally bears this
out, but of course there are exceptions. Mendota produced one nuisance
bloom in the two years’ study, unless the masses of filamentous algae be
so called despite its low nitrogen average. Wingra and Geneva, despite low
phosphorus averages, produced many blooms. But virtually all of these
were very small organisms, and the term bloom applied only when there
were more than 500 of some species per ml of raw water. No discolora-
tion or nuisance would have been evident.
Positive results are equally evident in Monona, Waubesa and Kegonsa.
Here a large amount of contributed fertilizing minerals came from properly
functioning sewage plant effluents, although agricultural drainage and indus-
trial drainage were also contributors. Blooms in these lakes were so
abundant and so frequent as to evoke legislative action on the part of the
shore residents. Most of the nuisance conditions here were due to blue-
green algae, Microcystis and Anabaena being the chief offenders.
But there is far too little evidence as to the causes of specific swarm-
ing growths of organisms. In shallow, warm lakes, accumulating nitrates
and phosphates seem to produce blue-green algae; but agricultural drain-
age into streams of moderate hardness seems to produce swarms of euglenoid
flagellates, small non-motile green algae and green flagellates belonging to
the Volvocales. Sulfuric acid drainage from exposed coal seams produces,
particularly, Euglena mutabilis (Lackey 1939). Distillery wastes have
shown most abundantly, Volvocales: the first United States record of
62 LIMNOLOGY, WATER SUPPLY AND WASTE DISPOSAL
Chlorobrachis gracilla was a bloom of them in whiskey distillery wastes at
Lawrenceburg, Indiana (Lackey 1942). Cedar swamp acid waters along
the Atlantic coast have produced blooms of the green flagellate Gonyosto-
mum semen at Woods Hole, in New Jersey and near Savannah, often
with an accompanying huge population of Euglena polymorpha. Reser-
voirs in areas underlain by granitic rocks may be troubled by yellow-brown
flagellates, such as Uroglena, Uroglenopsis, Synura, Chlorodesmus and
similar forms. Flagellates of these types are common to waters whose pH
tends toward acidity and are almost lacking in waters which are prevail-
ingly hard. The pattern behind many blooms is reasonably clear, but
specific causes are not clear and probably causes are due to combinations
of conditions. An accumulation of nutrients is certainly necessary. Small
streams draining sparsely inhabited areas along the Columbia River had
as small plankton populations as have been found despite summer tem-
peratures and low, clear water stages. Positive evidence is found in the
increased plankton populations of fertilized fresh water fish ponds, as well
as marine experiments at Milford, Connecticut (Loosanoff and Engle 1942) ;
Woods Hole; and lochs in Scotland (Gross et al. 1946).
Control of nuisance conditions has followed three general lines. In
the Wisconsin lakes a sewage treatment plant was put into operation and
control of some industrial wastes was initiated. Further control by copper
sulfate was used. An attempt was made to secure legislative action for
diversion of sewage plant effluent. Storm sewer wastes and agricultural
drainage were neglected. None of these schemes achieves more than par-
tial success. Treatment of sewage reduces the B.O.D., and by maintaining
oxygen and decreasing putrescible matter, changes the nature of blooms
from saprophytic organisms (mainly bacteria) to presumably altogether
holophytic ones. This probably decreases the nuisance, but leaves an
abundance of available N and P in food form. Copper sulfate treatment is
temporarily successful, but since copper accumulates in the bottom mud,
where it apparently destroys clams, worms and insect larvae, its long con-
tinued use is questionable. The same question should be raised for recently
developed algacides of other natures which upset biologic balance. Diver-
sion of sewage or sewage plant effluents from a lake to a stream merely
begs the question. The streams near Madison are already extremely rich
in plankton, and additional food might cause nuisances therein.
Control or elimination of bloom nuisances thus far is purely tem-
porary. The most promising investigations would seem to aim at the
removal of phosphorus. Nitrogen might at times be available by fixation
from the atmosphere. But before phosphorus removal is attempted, further
studies of the amounts and mechanism of contribution from agricultural
drainage should be made. In some instances, as when fertilizer is spread
on iced-over fields, it appears the farmer is paying for fertilizer which, on
the first thaw or rain, at once washes into streams or lakes. The biology
of industrial wastes needs much more study. The wastes of tanneries have
a B.O.D. averaging 1200 ppm; those of milk and distillery wastes are far
PLANKTON AND NUISANCE CONDITIONS IN SURFACE WATER 63
greater. Many wastes, such as those of paper and chromium plating indus-
tries, are indirectly or directly toxic, even though they leave the oxygen
content of water largely unaffected. Such toxic effects may likewise be
nuisances. Prevention of pollution or poisoning of shellfish areas, bathing
beaches, lakes, and streams is better than cures. And if the biochemist
or chemical engineer can achieve prevention by recovery of useful by-
products as an economic measure, very little legislation will ever be neces-
sary.
REFERENCES CITED
Fitcu, C. P. et al. 1934. “Water bloom” as a cause of poisoning in domestic animals.
Cornell Vet., 24, 1: 31.
Gross, F., Raymont, J. E. G., Nutman, 8. R. anp Gautp, D. T. 1946. Application of
fertilizers to an open sea loch. Nature, 158, 4006: 187-189.
Hervey, R. J. 1946. Abstract. Studies on the toxicity of algae for animals. Personal
communication.
Lackey, J. B. 1939. Aquatic life in waters polluted by acid mine waste. Pub. Health
Rpts., 54, 18: 740-746.
. 1942. The effects of distillery wastes and waters on the microscopic flora
and fauna of a small creek. Pub. Health Rpts., 57, 8: 253-260.
Loosanorr, V. L. anp Encus, J. H. 1942. Use of complete fertilizers in cultivation of
micro-organisms. Science, 95: 488.
Sawyer, C. N., Lackey, J. B. anp Lenz, A. T. 1944. Investigation of the odor nuisance
occurring in the Madison Lakes, particularly Lakes Monona, Waubesa, Kegonsa,
from July, 1943, to July, 1944. Part II. Biological. Report for the Governor’s Com-
mittee of the State of Wisconsin, Madison.
Starr, Univ. Miami Marine Lasoratory. 1947. Red tide and fish mortality on the
Florida West Coast. Special Service Bul., Coral Gables, Fla.
PRELIMINARY STUDIES ON THE VIABILITY AND
DISPERSAL OF COLIFORM BACTERIA IN THE SEA*
By BOSTWICK H. KETCHUM, CORNELIA L. CAREY, AND MARGARET BRIGGS
WOODS HOLE OCEANOGRAPHIC INSTITUTION, WOODS HOLE, MASS.
THE DISPOSAL of sewage in the sea is widespread and increasing. There
is, however, little information to indicate how much sewage a given body
of water will accommodate and even less on the fate of the pollution bac-
teria in the sea. The economic effects of polluted estuaries are already
evident, since large areas have been closed for the taking of shellfish and
many beaches throughout the country have been posted as unsatisfactory.
These problems will probably become more acute, because the disposal of
sewage is essential and the sea provides an efficient means of dispersion.
Harbors and estuaries frequently contain many thousands of bac-
teria per ml, a large proportion of which may be enteric species. In the open
sea, however, the bacterial counts normally range from 50-200 per ml,
and the coliform bacteria are never found in open, unpolluted sea water.
This tremendous decrease in numbers occurs within a short distance from
the mouth of the harbor or estuary (Calif. State Dept. Pub. Health 1943;
Knowlton 1929; Mass. Dept. Pub. Health 1936; Warren and Rawn 1938;
Weston 1938; Winslow and Moxon 1928). It is clear, therefore, that the in-
troduced bacteria do not persist for extended periods in the sea. The relative
importance of dilution of the polluted water by sea water, of the death of
the coliform bacteria, of sedimentation and predation by animals has never
been clearly assessed in the marine environment.
Our studies on this problem have included laboratory investigations of
the viability of Escherichia coli in sea water and surveys of some polluted
areas selected in the hope that the various factors in the disappearance of
pollution bacteria could be evaluated. The results described here must be
considered of a preliminary nature.
The results of our laboratory investigations of the death rate of
Escherichia coli in sea water will be described first. Previous investigations
of this problem have given widely divergent results, varying from death
rates much more rapid than are found in fresh waters (Calif. State Dept.
Pub. Health 1943; Carpenter, Setter and Weinberg 1938; ZoBell 1936,
1946) to the conclusion that sea water is neither antiseptic nor inimical to
enteric bacteria (Dienert and Guillerd 1940). We have found that the
laboratory treatment of the sea water influences the results greatly. The
use of artificial, synthetic or diluted sea water cannot be expected to give
results which will correspond to the natural phenomenon.
* Contribution No. 446 from the Woods Hole Oceanographic Institution.
64
STUDIES OF COLIFORM BACTERIA IN THE SEA 65
When natural, unpolluted sea water is brought into the laboratory and
stored in the dark a tremendous growth of the bacterial population takes
place. This growth and the effect of adding Z. coli to the water are shown
in Figure 1.* The total population of the raw sea water increases to a
maximum in three days, then decreases to a more or less uniform popula-
tion of about a million cells per ml. A slight initial increase in bacterial
numbers is also detected in the water to which the coliforms were added.
This period of growth of the mixed population is followed by a decrease
in numbers so that the final populations are approximately the same
whether EH. colz were added or not.
O-Totet Bacteria in Rew Sea Water
Total Bacteria in Raw Seo Weter
©- inoculated with 10° £.Coli sce
Cetiform Bacteria in Inoculated
hers Water
Number of Bacteria per CC, (tog scale}
Time in Days
Fic. 1. Growth of marine bacteria
and the viability of Escherichia coli in
untreated sea water.
The concentrations of E. coli were estimated independently in this
experiment by inoculating lactose broth fermentation tubes. The indicated
numbers of EH. coli thus obtained are also shown in Figure 1. They decrease
regularly from the initial inoculum of 10® cells/ml and after approxi-
mately seven days only a millionth of this population persists. Clearly,
the conditions which are suitable for the growth of marine bacteria are
inimical to the growth or persistence of the coliforms. It appears that the
final populations in both the raw sea water and in the water inoculated
with E. coli consist of the normal sea water organisms.
If, instead of using untreated sea water, Escherichia coli are intro-
* The numbers were determined by plate counts after 7 days’ growth on a medium
containing 1 gm glucose, 1 gm peptone, 0.05 gm NaHePOs, 15 gm agar in 1 liter of
aged sea water.
66 LIMNOLOGY, WATER SUPPLY AND WASTE DISPOSAL
duced into water sterilized by autoclaving or by boiling, the results shown
in Figure 2 are obtained. In the autoclaved water the death rate of the
coliform bacteria is very slow. The maximum decrease observed was to one-
fifth of the total population in a period of seven days. In the boiled water
the death rate is more rapid and is similar to the rate found in the untreated
sea water. It is clear from these results that the bactericidal action of sea
water is destroyed by the heat of autoclaving, but is unaffected by the
milder boiling treatment.
Another observation shown in this figure is that a second or subsequent
inoculum of E. coli dies off more rapidly than the first. In these experi-
10
Autoclaved
Sea Wailer
°
& putoclaved
Seo Woter V7
0.1
Reinoculated
Autoctoved Sea Woter
Boiled
\ Sea Water
E.Coli Surviving Fraction (tog scale)
E.Coli Surviving Fraction (log scale)
Reinoculoted x
Boiied
Sea Water \ @
\
‘\
\
ee eee
° 2 4
Time in Days Time in Doys
Fic. 2. The viability of Escherichia coli in autoclaved and in boiled sea water. The
original inoculation of E. coli provided a population between 5x107 and 5x108 cells/ml.
The surviving fraction is plotted. Different symbols represent different experiments.
ments the water receiving the first inoculum was stored until no viable cells
were found. This took about 20 days for the autoclaved sea water, 5
to 10 days for the boiled water. When another inoculum of E. coli was
added to the water, the bacterial counts decreased as shown by the heavy
lines. The death rate in the reinoculated autoclaved water is eight times
as great as the rate observed for the first inoculum. A threefold increase
in rate was observed with the boiled water. It may be presumed that the
greater death rates observed with reinoculated water correspond to what
would be obtained in polluted estuaries.
The coefficients of death rate, as shown in Table I, summarize the
results of these laboratory investigations. This coefficient is the reciprocal
of the time (in days) for the population to decrease to one-tenth its original
STUDIES OF COLIFORM BACTERIA IN THE SHEA 67
TABLE I
AVERAGE COEFFICIENTS OF DeatH Rate or ESCHERICHIA COLI
IN SEA WATER TREATED IN VaRIOUS Ways
Coefficient of Death Rate (k)
Treatment ; y
First inoculum | Subsequent inocula
days—! days—1
INORG! 5/d ahalosc SERS SUR are ee RR a Ney ad 1.00
Boned opm ira. eA Vets ee cue ream aaye 1.15 3.48
mucoclaved 10-15) mins) ess aos ee 0.04 0.35
value. Thus, a coefficient of 1.0 means that a tenth of the population dies
daily; the coefficient 0.04 indicates that 20 days are required for an
equivalent mortality. These experiments show that sea water has a potent
bactericidal action. The activity is decreased greatly by autoclaving, but
not by boiling the sea water. It is increased by previous “pollution” of
the water with E. coli.
Further investigations are necessary to determine how the bactericidal
activity of sea water varies with natural conditions. Is there a seasonal
variation which might be correlated with variations of the normal popula-
tion of the sea? Is the bactericidal activity greater in polluted harbors
than in the open sea, and what are the effects of dissolved organic matter,
oxygen supply and other variables associated with pollution? What is the
identity or nature of the bactericidal activity?
Some of our experiments suggest that antibiotic substances produced
by marine organisms may be responsible for the death of the pollution
bacteria. They do not exclude, however, the possibilities that bacteri-
ophage or autolytic or degenerative products of the coliforms themselves
may also be involved. It is possible that all three contribute to the final
action. It is significant, however, that Rosenfeld and ZoBell (1947) have
recently described the production of antibiotic substances by several species
of marine bacteria. None of these antibiotics was inimical to gram nega-
tive species and E. coli was not included among their test organisms. In
our experiments pour plates of the normal sea water bacteria were made
and the population allowed to develop for 48 hours. The surface of one
of each pair of plates was then flooded by a suspension of E. colz, the excess
being poured off. After a total time of four days the plates were inspected
and clear areas were found surrounding some of the sea water bacteria.
These results suggest that some of the sea water forms produce substances
inimical to E. colt.
It is pertinent to inquire whether the results of these laboratory experi-
ments bear any relation to the phenomena which occur in nature. In the
sea the mortality of the bacteria may be completely obscured by the cir-
culation and mixing of water masses. The dilution of the polluted water
68 LIMNOLOGY, WATER SUPPLY AND WASTE DISPOSAL
with sea water disperses the bacteria, and this effect must be accounted for
in order to observe the death rate. In complicated estuarine situations,
where there are several sources of contamination, it becomes especially
difficult to differentiate between mortality and dilution. The recent develop-
ment of an instrument for the continuous recording of salinity and tem-
perature, however, has made it possible to conduct more rapid and accurate
surveys of hydrographic conditions. From the data thus obtained the
rate of dilution of the introduced contaminated water can be estimated.
It is this possibility which has stimulated our interest in the field.
A comparatively simple picture of the fate of sewage bacteria in sea
water may be found at the Sewer Outfall at New Bedford, Massachusetts.
Here the sewage is introduced from a seven-foot diameter outfall pipe at
a depth of 30 feet, 1100 yards offshore into water that is relatively uncon-
taminated. During the rising tide the flow of sewage is decreased and
sometimes stops completely. During the falling tide the sewage wells
oe ov © & &
cy)
100 Bo. @ GAS PRODUCIWO OROANISI
ow
DISTANCE PROM OUFPALL, YARDS
Fic. 3. The salinity and the indicated
numbers of organisms producing gas
from lactose broth at various distances
from the New Bedford Sewer outfall.
out of the pipe in sufficient volume so that it is readily detectable. It is,
indeed, difficult to obtain samples directly in the upwelling column since
the boat’s course is deflected by the rising and spreading current. A
tidal current flow of about half a knot sweeps past the location of the
outfall, and, on the ebb, carries the polluted water seaward. Several
series of observations on the distribution of salinity and coliform bacteria
have been made at this location.
The surface distribution of salinity and bacteria along the axis and
across the axis of the tidal current are both shown in Figure 3. As
would be expected, the salinity of the outfall water is low com-
pared to the surrounding sea water of Buzzards Bay. The introduced
sewage is diluted with 13-14 volumes of sea water by the time it appears
at the surface. In crossing the axis of current in the neighborhood of the
outfall, the bacterial numbers increase to a maximum at a location near
the outfall and then decrease again on the other side. The distribution of
salinity and of bacteria along the axis are similar except that the down-
stream distances required to reach a given concentration are greater.
STUDIES OF COLIFORM BACTERIA IN THE SEA 69
The bacterial numbers are, however, always lower than would be pre-
dicted on the basis of dilution alone. To illustrate this point the dilution,
expressed as percent outfall water in the sample,* and the surviving per-
centage of bacteria in the sections across and along the axis of current
flow are plotted in Figure 4. If the bacterial count decreased only because
of the dilution of the water the two sets of data would be superimposable.
The surviving percentage of bacteria, however, is always less than the
percent dilution of the water.
The extent by which the numbers of bacteria are less than the expected
numbers is shown in Figure 5, where the numbers of bacteria found are
10,000 J X - across flow
0 - with flow
J) i
: Vi Dilution
A tf
Saas
Bh
: ‘
: :
H H
: :
‘
; H
iS cterle
Section
long Flow
DILUTION, % OUTPALL @ATER
uo
3
°
BACTERIA SURVIVING PERCEPT
No. OF GAS PRODUCING ORGANISMS POUND
DILUTION, % OUTFALL WATER
DISTANCE PROM CUTFALL, YAXDS Based on Salinity Change
Fic. 4. The dilution of the outfall Fic. 5. The number of gas-producing
water, as calculated from the salinity organisms found plotted against the
change, and the percentage of bacteria dilution of outfall water as calculated
surviving at various distances from the from the salinity change.
New Bedford Sewer outfall.
plotted against the dilution of the water. If the bacteria diminished in
direct proportion to the dilution of the water a straight-line correlation
would be expected since dilution of the water by 50% would lead one to
expect half of the original bacterial population. The bacterial numbers
are, however, substantially lower than can be accounted for by dilution
alone. In the simplified situation at the New Bedford Sewer outfall, there-
fore, it is clear that the coliform population disappears much more rapidly
than would be expected on the basis of simple dilution by sea water.
* Hach sample of water is considered a mixture of the polluted, fresher water with
sea water, 1.e.
XS, Lh G_[08 = hh
in which X is the fraction of polluted water of salinity S,, and S and Sj are the salini-
ties of the sea water and of the diluted water sample.
70 LIMNOLOGY, WATER SUPPLY AND WASTE DISPOSAL
A more complicated picture is found in polluted estuaries where the
circulation of the water masses play a more important role. The water
exchange in an estuary includes a net outward movement of surface water
contributed by rivers at the head of the bay and a net inward movement
of the denser more saline sea water at mid-depth or near the bottom.
Along the length of the estuary vertical mixing tends to increase the
salinity and the volume of the outflowing surface waters with the result
that the total surface outflow at the mouth of the estuary is greater than
the flow into the estuary from the rivers. An imporant corollary of this
generalization is that introduced pollution can be removed only in the sur-
face waters, since any material which sinks to the deeper water moves in a
net “upstream” direction.
It may be pointed out that the float tests, which have long been
standard techniques in the study of such situations, give only a small part
LONGITUDINAL SALINITY SECTION OF MOUNT HOPE BAY
TAUNTON
2052075 290 295 2975 SEAWARD
IN FEET
2 3
NAUTICAL MILES
Fig. 6. The distribution of salinity in
a longitudinal section of Mount Hope
Bay at the end of the ebb and flood
tides.
of this complicated picture. The floats show only the net flow of the sur-
face waters, and give no information concerning the rate of vertical mixing.
In studying the effects of various wind conditions the use of floats is
especially deceptive. The wind drives the float more rapidly than it drives
the water. The same wind, furthermore, increases vertical turbulence to
such an extent that the pollution is dissipated more rapidly instead of being
carried farther as suggested by the float results. Measurements of the
salinity of the water provide the most useful tool in studying the exchanges
and dilution of various water masses.
Typical salinity contours in Mount Hope Bay, below Fall River,
Massachusetts, at the end of the ebb and flood tides are given in Figure
6. These data, collected by the continuous salinity-temperature recorder,
illustrate the general principles of estuarine circulation described in the
Survey of the River Tees (1931, 1935, 1936). The picture at low tide
shows relatively flat, elongated salinity contours demonstrating the greater
surface flow of the less saline and consequently lighter river water. The
deep water retains much of its dense, high salinity character. Follow-
STUDIES OF COLIFORM BACTERIA IN THE SEA 71
ing the flood tide all of the contours are shifted upstream, and the gradients
of salinity distribution with depth are more gradual.
An important contribution of water circulation to the disposal of
pollution is the rate of dilution of the contaminated water. This occurs,
9 :
CAN Spire
NAUTICAL MILES
iia el
0) I 2
Fic. 7. The ratio between the observed and the expected bacterial counts at various
locations in Mount Hope Bay at different stages of the tide. The expected numbers
are computed by correcting the numbers introduced in the Taunton River (NE.
corner of chart) by the degree of dilution with sea water.
not only by horizontal mixing, but also by the vertical mixing of the sur-
face water with the more saline deeper water. The rate of this mixing
is increased as the density gradient between the surface and deeper waters
decreases. As shown by the salinity contours in Figure 6 vertical mixing
72 LIMNOLOGY, WATER SUPPLY AND WASTE DISPOSAL
will be most rapid at the end of the flood tide, since at this time the vertical
distribution of salinity and density is most uniform. Any increase in wind
force will increase the rate of this mixing, which will tend to diminish the
salinity gradients still further.
The distribution of bacteria in relation to the phase of the tide in
Mount Hope Bay is shown in Figure 7. In this figure the bacteria are
represented by a ratio between the number actually found and the number
expected. The number expected is calculated by correcting the number
introduced in the river water at the head of the bay by the degree to
which this water has been diluted by mixing with sea water. The ratio
thus obtained is plotted against the time after high water at each of the
locations shown in this figure. If dilution were the only factor operative
in this area all of these curves would be flat and show no variation with
the tide. The fact that all of them increase above unity indicates that
there are contributions of bacteria from sources other than the river mouth.
This is to be expected since the area is densely populated and several
sewerage systems empty directly into the bay. The interesting fact, how-
ever, is that in spite of this additional pollution, the numbers at each loca-
tion fall far below the expected numbers during the period of high tide.
Since the effect of dilution has been cancelled out it is clear that this
diminution is the result of other processes which deplete the bacterial
population.
To summarize, our investigations have indicated that the coliform
bacteria disappear rapidly from normal sea water under laboratory condi-
tions. This disappearance is not related in a simple way to the chemical
content of sea water since autoclaving the water eliminates its bactericidal
activity. The lethal factors, or substances, are apparently organic in
nature and heat labile.
That the bactericidal property of sea water is important under natural
conditions is indicated by the fact that the disappearance of coliform bac-
teria in the sea is much more rapid than can -be accounted for by the
dilution of contaminated water with sea water. It is fortunate indeed that
this is the case, else our heavily polluted harbors would be unbearable.
Several additional problems must be studied in order to complete the
picture. It would, of course, be desirable to determine the nature of the
bactericidal substance or factor in sea water. The distribution of bac-
tericidal activity in waters and muds collected from polluted areas and
at varying distances from shore should aid in identifying its character.
The potency of a given body of water may be expected to have an im-
portant relation to its ability to accommodate introduced pollution. Finally,
considerably more fundamental information is needed concerning the
principles which govern the mixing of water masses. When this informa-
tion is available it should be possible to plan marine outfalls so that the
introduction of pollution will lead to the minimum interference with the
fisheries and economy of the area.
STUDIES OF COLIFORM BACTERIA IN THE SEA 73
ACKNOWLEDGMENTS
The authors gratefully express appreciation for the interest and advice
of Dr. Selman A. Waksman, who initiated our laboratory studies, and of
Dr. Alfred C. Redfield, who has encouraged our investigations of sewer
outfalls and estuarine conditions. The contributions of Dr. William L.
Ford, who conducted the hydrographic investigations and collected the
salinity data used in this report, and of Mr. C. M. Weiss, who made the
bacterial counts at New Bedford, are gratefully acknowledged.
REFERENCES CITED
Cauir. State Derr. Pus. HeartH. 1943. Report on a pollution survey of Santa Monica
Bay beaches in 1942. 69 pp. Calif. State Printing Office, Sacramento, Cal.
CarPenter, L. V., Setter, L. R. anp WEINBERG, M. 1938. Chloramine treatment of sea
water. Amer. Jour. Pub. Health, 28: 929-934.
Drenert, F. anp GuILuerD, A. 1940. Etude de la pollution de l’eau de mer par le déverse-
ment des eaux d’egouts. Ann. d’Hyg. Pub., Ser. 5, 18: 209-217.
Knowuton, W. T. 1929. B. coli surveys, Los Angeles ocean outfalls. Calif. Sewage
Works Jour., 2: 150-152.
Mass. Dept. Pus. Heattu. 1936. Report of the special commission on the investigation
of the discharge of sewage into Boston Harbor and its tributaries. House No. 1600.
Wright & Potter Printing Co., Legislative printers, Boston, Mass.
RosENFELD, W. D. AnD ZoBELL, C. E. 1947. Antibiotic production by marine microorgan-
isms. Jour. Bact., 54: 393-398.
SURVEY OF THE River TEEs.
Parr I. HyprocrapHicaL. 1931. [Gt. Brit.]| Dept. Sct. and Indus. Res., Water Pollut.
Res. Tech. Paper 2: 92 pp. H. M. Stationery Office, London.
Parr II. ALExANpeEr, W. B., Soutuaatsr, B. A. AND BASSINDALE, R. 1935. The Estuary,
Chemical and Biological. Water Pollut. Res. Tech. Paper 5: 171 pp.
See also summary in Mar. Biol. Assoc. Jour. U.K.NS., 20: 717-724, 1936.
Warren, A. K. anp Rawn, A. M. 1938. Disposal of sewage into Pacific Ocean. Modern
Sewage Disp. pp. 202-208. Federation of Sewage Works Assoc., New York.
Weston, A. D. 1938. “Disposal of Sewage into the Atlantic Ocean,” Modern Sewage
Disp., pp. 209-218. Federation of Sewage Works Assoc., New York.
Wins tow, C. E. A. anp Moxon, D. 1928. Bacterial pollution of bathing beach waters in
New Haven Harbor. Amer. Jour. Hyg., 8: 299-310.
ZoBruu, C. E. 1936. Bactericidal action of sea water. Soc. Expt. Biol. and Med. Proc.,
34: 113-116.
. 1946. In Marine Microbiology. Chapter XVI, 182-192. Chronica Botanica
Co., Waltham, Mass.
THE ALGOLOGISTS’ PART IN CITY AND INDUSTRIAL
WATER SUPPLY PROBLEMS
By CLARENCE E. TAFT
THE OHIO STATE UNIVERSITY, COLUMBUS, OHIO
For THE past ten years I have had the privilege of being in charge of
the Algae Studies in connection with the Columbus City Division of Water,
Columbus, Ohio. During that period many problems have been met and,
I hope, solved through the practical application of the accumulated knowl-
edge concerning the algae. With this somewhat limited background in a
science which was not new even at the turn of the century, I approached
the preparation of this paper with two questions in mind. Their answers
I consider fundamental to the understanding and solution of our problems.
The first question is, why is the Algologist peculiarly qualified to aid
in Water Supply Problems? The second question is, what part does he
actually play in the solution of these problems? The answer to the first
is basically one of fundamental training, while the second is answered by
the degree to which he applies his knowledge. Let us return for a moment
to the first question where we must consider the qualifications of the
Algologist. These qualifications are several in number. He must recognize
the fact that algae are living organisms, unicellular or multicellular, and
that their physical and chemical properties are such that they may influ-
ence the potability of water, either by mechanical or chemical means. He
must recognize that in the algae, as is true of any plant which has specific
hereditary complexes, the environment determines the growth and repro-
duction through its influence upon the physiological processes within the
living cell. He must understand the action as well as the interrelation-
ships of these environmental factors so as to know how and where to take
samples in order that his final results will be more than representative of
microhabitats. Also, he must be able to interpret the samples after they
have been prepared for analysis. This last I consider of the greatest
importance. It involves not only a knowledge of the algae, but a famili-
arity that will allow their identification with medium power magnification.
With the counting chambers used it is impossible to use the higher magnifi-
cations of the microscope, so if one is not familiar with most of the com-
mon algae and cannot at least call them by their generic names as one
would speak of an old friend, then that person is at a decided disadvantage,
or rather completely lost. This familiarity can only be gained by hours of
looking, painstaking key-work, and a thorough understanding of the life
histories of all common algae. This last is of decided importance because
much of the material encountered in some samples is undergoing reproduc-
tion and to the uninitiated has very little resemblance to the mature indi-
vidual.
74
CITY AND INDUSTRIAL WATER SUPPLY PROBLEMS 79
I find that it is this last, or the identification, that is the most difficult
for people to understand. A summer seldom passes when I do not have
a call or letter from some individual who asks if I can give him a couple
of hours so he can learn to recognize the algae that may be in the water
supply for which he is responsible. Although I feel that these requests
may constitute a part of the Algologist’s work, especially if he is a member
of an educational institution, I know it cannot be done in the few hours
available. Such a procedure, if attempted, can only lead to inadequacy and
questionable results.
Briefly, we can now summarize the answer to the first question in one
statement. The Algologist not only knows the names, but also some of
the physiological and ecological relationships, of the organisms with which
he works.
Let us now proceed to the second question by assuming that the indi-
vidual has the necessary qualifications. The success which he will attain
in the solution of City or Industrial Water Supply Problems will be propor-
tionate to the degree of successful application of the above principles. He
has a choice of two procedures, either of which may lead to the solution
of the problem immediately at hand. One is by a complete and detailed
survey of the water supply involving chemical and physical analyses as
well as qualitative and quantitative analyses of both phyto- and zooplank-
ton. Here the plankton data may be extracted for immediate use at any
point during the survey, if such is necessary. The other data may be
used immediately, or they may be incorporated in the records and later
put to use in future studies of aquatic environments, which in turn lead
to a better understanding of water supplies. Such a study as this usually
necessitates the services of a permanent Staff Member who in reality can
be rated as a highly trained Limnologist. Today I do not intend to deal
with the problems of the professional Limnologist, but only with the occa-
sional and varied problems which concern the consulting Algologist.
For those systems where such detailed and elaborate records are con-
sidered non-essential by those in charge, then the second procedure is ap-
plicable, and I presume is the most widely used. Possibly we can con-
sider Columbus, Ohio, as a fair example. Its water supply lies mainly in
the Scioto River, which is a drainage system in the west central part of
the State. Two reservoirs were created by Griggs Dam about four miles
west by northwest of the City, with a capacity of approximately 1,627,-
000,000 gallons, and by O’Shaughnessy Dam twelve miles north, with an
approximate capacity of 5,000,000,000 gallons. In both cases the dams
were constructed across narrow, rocky gorges, so that much of the im-
pounded water is in vertical walled reservoirs. This is especially true of
Griggs Reservoir. Because of the nature of the watershed which is almost
entirely farm land the water often maintains a fairly high turbidity fol-
lowing storms which result in severe run-off. Spring thaws also contribute
turbidities which may continue well beyond the middle of June. Clear
water, with intermittent periods of turbid water caused by rains, then
76 LIMNOLOGY, WATER SUPPLY AND WASTE DISPOSAL
continues until the advent of the autumn rains.
During the summer of 1937, Mr. Charles P. Hoover, Chief Chemist
for the Columbus City Division of Water, asked me to carry out some sort
of an algal survey for the Department. This type of work was new to
me at the time, but I felt that a weekly survey for one year would
be valuable as a base plan. The samples were taken at Griggs Reservoir
and proved their worth because we found the winter months to be
especially unproductive. Little beyond sporadic sampling was done
during the summers of 1938, ’39, ’40, and ’41. These fortunately did not
show any serious algal problems. I say fortunately because such occasional
sampling would have been of little value if a “bloom” of some particularly
bad alga had started. It was not until the spring of 1942 that we went on
a basis of regular samples beginning with the clearing of spring turbidity
and extending to the period of fall turbidity, or of periods of low temper-
ature and overcast sky. We are very fortunate (algologically speaking)
in having spring and fall turbidity as it reduces our danger period to
about four months, July to November. Two stations were established at
Griggs Reservoir, one near the Dam crest, and one about 300 yards above.
Two stations were established at O’Shaughnessy and two more about two
miles farther north. The four stations above O’Shaughnessy Dam fulfilled
a dual purpose. They were located so as to check the possible influence of
sewage effluent on plankton production and as a warning of what we might
expect down river at Griggs Reservoir.
Next in importance was the method of collecting. Consideration of
this factor was definitely colored by the needs and desires of those in
charge of the Water Plant. Should the collections be extremely accurate,
should they show absolute total plankton, should counts be in standard
units, or would fairly accurate quantitative counts be satisfactory. The
judgment that the Algologist exercises here will determine to a great extent
what the Chemist will later consider success or failure. Furthermore, to
be perfectly frank, here is where the problem of relative cost enters, if this
is a problem. For a trial period we took each sample by putting 25 gallons
of river water through a Number 20 Bolting Silk Plankton Net. This
sample was made up to 50 ee during preservation and then standard pro-
cedures used to effect a count, although the “Standard Unit” was not
adopted. The advantages are that it requires a minimum of equipment,
that most any of the Water Plant personnel can be readily trained to make
the collections, and also that all organisms of any considerable size are
retained. A few of the very small organisms do go through but these
as far as we know have little effect on the water.
Counts of the organisms in these samples are made and the results
translated directly into organisms per gallon of raw river water. Where
random samples through the summer would have little value, these weekly
samples present an integrated picture of the plankton concentrations of
any one station. All that is now necessary is for the algologist to analyze
them on the basis of particular genera present or upon the basis of total
CITY AND INDUSTRIAL WATER SUPPLY PROBLEMS 77
numbers of organisms. In general the first is of greater importance. Know-
ing that only certain genera are real trouble makers, the algologist watches
for them especially. If one should happen to appear, he is on his guard
and when the next samples come in his attention is directed to it. If the
number of individuals of this organism is great when first seen, then con-
trol may be essential immediately. One variation of the rule is for Synura.
If one colony appears in the collections, then treat and treat fast. It may
be that no organisms of especial significance appear, but that the com-
bined total of all organisms rises steadily and rapidly. Here one must
use his judgment as to the best procedure; in other words, he must be able
to predict the probability of a “bloom.” As there is a definite correlation
between ‘‘water blooms” and environmental conditions the quality of one’s
predictions depends largely upon the understanding and interpretation of
the environment. In the case postulated above if the weather continues
to be warm with bright sunshine and little wind, I would recommend treat-
ment. Only because of these regular collections of algae and with a
knowledge of the probable effects of environment, can one anticipate plank-
ton trouble and prevent it. At Columbus we have seldom found it neces-
sary to apply copper more than twice during any summer since 1942.
The preceding discussion illustrates what is probably the best known,
if not the most important, part played by the algologist. His position is
somewhat that of a “watch-dog.” He anticipates trouble and recommends
precautionary measures before the troubles reach serious proportions.
Along with these regular surveys, the algologist sometimes can be of
assistance in settling disputes that may arise in connection with water plant
operation or policy. An example of this occurred in Columbus where some
wanted to use Griggs Reservoir as a power boat course. The City was
to build and rent docks to accommodate these boats. Although it pro-
vided an additional recreation area to the City Park System, as well as
some additional income, a few individuals felt that maybe boats should
not be in the water supply. My opinion was that these boats might be
beneficial in the dispersion of algal blooms. Subsequent surveys tend to
show that this heavy, and may we say somewhat wild boat traffic, has done
much to disperse algal concentrations during the critical July and August
days.
Another case occurred in which suddenly and for no apparent reason
the water entering the mains had a violent odor and flavor. A quick
check at the Reservoir disproved the possibility that it was of algal origin,
and turned the investigation to the river between the Reservoir and the
pumping plant. It was soon discovered that run-off from a new black
top pavement was the cause.
Let us now assume that everything possible has been done and that
water of as near perfect quality as can be reasonably expected has entered
the mains. As a reward one would expect that they could sit back and
accept the plaudits of the community. Through my contacts with Mr.
Hoover and the Columbus Water Department, I find that this is not always
78 LIMNOLOGY, WATER SUPPLY AND WASTE DISPOSAL
the case. Let something go wrong with a manufacturing process in which
City water is used and the first finger of suspicion is directed at that water.
The algologist is not always the individual to finally clear the situation,
but at times his knowledge will aid the plant personnel in clearing the water
supply of suspicion. For instance, I was called in on a case where the
bottle of the office water cooler had acquired a brilliant green film. Exami-
nation proved definitely that it was the alga Chlorella. The management
was positive that it came in with the City water and demanded that the
situation be corrected. I found that the empty bottles “just stood around”
and that the cooler occupied a position in the corridor in front of a large
window. The solution of the problem was now relatively simple. First
was to wash and stopper all unused bottles. Second, scrub the inside of
the cooler so as to eliminate this as a source of infection. Third, move
the cooler into an area of reduced light where Chlorella cannot grow as
well.
Of a more serious nature are the problems of those industries that use
the same water repeatedly in their cooling systems after it has passed over
cooling towers or through cooling basins. Algae develop at astounding rates
on these towers or in the basins, and unless they are removed before the
water re-enters the cooling system they leave gelatinous or other organic
debris inside pipes and fins. This results in a perfect culture medium for
bacteria and fungi and subsequently in clogging. Such clogging is often
blamed on impurities supposed to have been in the original water used,
or on the premise that algae must have gotten in through this medium.
Few realize that an open dish of water exposed for a few days will soon
have a very nice culture of many algal genera. Again the algologist can
do more in preventing these situations than in their cure.
The algologist also has a part to play in water supplies involving
wells. The question was raised as to the purity of water from a well in
Northern Ohio. Samples which I examined and which came directly from
the pump contained several genera of green algae, as well as several indi-
viduals of the zooplankters. Knowing that light is necessary for chloro-
phyll development, and that green algae continue to live only in light, and
that zooplankters usually have algae somewhere in their food chains, I
could safely say that the stream tapped by the well headed up in some
nearby lake or pond, or that somewhere there was seepage. Either situa-
tion could result in polluted water. Another case superficially similar to
this, but with a totally different ending, occurred near Columbus. The
driller had brought in a well in the gravel drift south and west of the
City, but samples from the pump showed a great deal of debris. Upon
examination this debris proved to be fragments of moss leaves, some algae,
and bits of zooplankters. But, and this was important here, these were
fossils. The well had acidentally been drilled into an inter-glacial bog
which had been covered by gravel following the retreat of the last glacial
ice. Although not desirable in the water supply, the condition of the
material definitely indicated that it was not the result of surface water
seepage.
THE USE OF COPPER SULPHATE FOR ALGAL CONTROL
AND ITS BIOLOGICAL IMPLICATIONS?
By JOHN B. MOYLE
FISHERIES RESEARCH UNIT, MINNESOTA DEPARTMENT OF
CONSERVATION, ST. PAUL, MINN.
INTRODUCTION
Durine the last 40 years coppers sulphate (CuSO,.5H,O) has been
used widely and effectively for the control of objectionable algal growths
in lakes and reservoirs. This salt is also poisonous to fish and aquatic
invertebrates. However, experimental work (Moore and Kellerman 1905;
Marsh and Robinson 1910; Ellis 1937) and the general observations of
many field workers show that usually plankton algae can be destroyed
with concentrations below those toxic to aquatic animals.
Most users of copper sulphate and investigators like those already
cited have been principally concerned with the comparative toxicity of
the salt to different animals and plants and with the immediate practical
results of algal control. To the conservationist there is another and a
wider viewpoint which is worthy of consideration. Evaluation of algal
control with copper sulphate in terms of immediate toxicity or in terms
of sanitary or esthetic gain is not enough. The long-time effect of repeated
copper sulphate treatments on the biological productivity of a water, espe-
cially on fish production, should also be taken into account. In an increas-
ing number of lakes algal growths are being controlled for such reasons
as elimination of obnoxious odors, improving conditions for swimming
and maintaining the value of shore property. For these waters, considera-
tion of the effect of copper sulphate on fish production is essential. Many
municipal water supplies also are used for public fishing. In these recrea-
tional values should not be overlooked.
Growth of most objectionable algae can be controlled with concentra-
tions of copper sulphate between .12 and .50 ppm. Fish, on the other hand,
tolerate considerably greater amounts. In a Minnesota hard-water lake,
concentrations as great as 1.2 ppm have been used without damage to a
mixed game and rough fish population. Surber (1943) reports that 2 ppm
copper sulphate did not kill small-mouth bass in hard-water ponds. Much
higher local concentrations have been used for snail control in hard waters
without fish loss (McMullen 1941) and Nichols et al. (1946) found that
in the hard water of Lake Mendota (alkalinity about 170 ppm) the lethal
concentration for large-mouth bass was “about 200 parts of applied copper
1 Investigational Report No. 76, Fisheries Research Unit, Minnesota Department of
Conservation, St. Paul.
79
80 LIMNOLOGY, WATER SUPPLY AND WASTE DISPOSAL
sulphate per million.” In soft water, fish and aquatic invertebrates are
much more susceptible to copper poisoning. The addition of 3 ppm to a
soft-water Nova Scotia lake by Smith (1935) resulted in nearly a complete
kill of fish and fish food.
It should be noted that fish kills may result from the use of copper
sulphate and not be due to copper poisoning. If treatment is delayed until
a heavy algal crop is present, decay of the algae killed may so reduce the
supply of dissolved oxygen that fish die of asphyxiation.
ALGAL CONTROL AND FISH YIELDS
In the simplest sense algae are the grass of our waters. They, with
the larger aquatic plants, are the synthesizers of organic material on which
all other aquatic life depends. This general statement is an over-simplifi-
cation, since the interrelationships within the aquatic “microcosm” are
immensely complex, but it does pose a very pertinent question. Will the
reduction of algal crops through the use of copper sulphate seriously affect
the potentialities of a water for raising fish and waterfowl?
Approaches to this problem in the literature are few and of an obser-
vational nature. Huff (1923), after considering 6 years of algal control
with copper sulphate in Lake Vadnais, near St. Paul, observes that “Fish,
... are apparently as abundant as they ever have been.” Domogalla (1935)
in reviewing 11 years treatment of Lake Monona, at Madison, does not
commit himself to a definite answer but remarks “the opinions of fisher-
men on that subject (effect of copper sulphate on fishing) vary a good
deal.” This problem has recently been brought to the attention of sports-
men by Schoenfeld (1947) in an article in Field and Stream, in which he
makes a general condemnation of the use of copper sulphate for algal con-
trol. He cites an unnamed Illinois pond which has been treated with
copper sulphate for 30 years and is “now completely sterile.” He states that
perch fishing in Lake Monona, which has been treated, is poor compared
to untreated Lake Mendota. There is also negative evidence which per-
haps should be considered. With the exception of Schoenfeld’s article,
no account has been found in which a decline in fishing has been proven
to be the result of continued use of copper sulphate for algal control.
The longest history of copper sulphate treatment in Minnesota is that
of the Fairmont water supply. Here since 1921 algal growths have been
controlled in Amber, Budd, Hall, and Sisseton Lakes. These lakes are
part of a chain lying in an ancient glacial river valley in Martin County.
They range in size from 84 to 513 acres, in average depth from 5.4 to 11.4
feet, are very hard and of high chemical fertility. Aphanizomenon is, and
has been since 1921, the principal objectionable algae (Huff 1922; Moyle
and Wilson 1946). Microcystis is also present and has at times been
troublesome. Poisoning of livestock drinking from Hall Lake has been
attributed to it (Fitch et al. 1934).
The Fairmont water supply lakes, together with untreated waters in
the same chain are quite heavily fished by anglers. All have large rough
COPPER SULPHATE IN ALGAL CONTROL AND IMPLICATIONS 81
fish populations, mostly buffalo and carp. Rough fish have been removed
regularly since 1923.
Five untreated lakes in this chain have been selected for a comparison
of rough fish yields from treated and untreated waters. The untreated
lakes, North Silver, South Silver, Wilmert, Martin, and Iowa, range in
size from 186 to 443 acres. They are shallow, fertile, and very similar to
the treated waters. As far as can be ascertained these lakes, with the excep-
tion of South Silver in 1921, have never been treated with copper sulphate.
Because most of the rough fish removal has been carried out in the winter
by seining under the ice, the fishing records are considered by seasons
rather than by calendar years. In all there have been a total of 137 fish-
ing seasons on the 9 lakes, 64 on treated and 73 on untreated waters. The
number of rough fish removal operations on any one lake ranges from
12 to 22, with an average of 15 for all.
For the last 24 years (1923-1947), the average rough fish yield per
fishing season was 132.1 pounds per acre from the 4 treated lakes and 117.7
pounds per acre from the 5 not treated. On the average, the yield of
the untreated lakes has been 9% less than of those treated with copper
sulphate. If fishing records are broken down into two long periods, 1923-
1933 and 1934-1943, to show trends, and a shorter period, 1944-1947, to
evaluate present conditions, a similar decline in rough fish production will
be observed for both treated and untreated waters (Table I). It appears,
TABLE I
RoucuH Fisu YIELDS IN PounpDs PER ACRE PER FISHING SEASON IN Two
Groups oF SOUTHERN MINNESOTA LAKES +
1923-33 1934-43 1944-47
Four treated lakes............ 143.6 (27) 127.9 (22) 76.8 (9)
Five untreated lakes........... 137.7 (39) 115.4 (39) 79.7 (12)
1 Parenthetical figures are the number of fishing seasons on which the average is based.
therefore, that most of the decline in the catch of rough fish in the treated
lakes must be attributed to causes other than copper sulphate—to such fac-
tors as repeated rough fish removal, fishing skill, weather, and the price of
fish. The somewhat greater decline in catch from the treated lakes may be
due to copper sulphate but there are so many variables involved that the
statistical validity of difference in yield cannot be proven.
From such information as we have on the Fairmont lakes, it appears
that the continued treatment with copper sulphate has not seriously affected
angling. Creel census carried out during the months of July, 1941, and
July, 1942, on 2 of the treated lakes, Amber and Budd, showed an average
catch rate of 2.28 fish per hour of fishing. The average catch rate dur-
ing these months for all Minnesota lakes was 1.61 fish per hour of fishing
(Hiner 1943).
82 LIMNOLOGY, WATER SUPPLY AND WASTE DISPOSAL
ALGAL CONTROL AND PrRropucTION oF FisH Foop
It has long been recognized by fish culturists that maximum fish pro-
duction is usually obtained with the aid of fertilization. Good results have
been obtained with inorganic fertilizers and with such organic fertilizers as
cottonseed and soybean meal. The aim of fertilizing with inorganic fertil-
izers is to produce a plant plankton crop. These minute plants are of
little direct importance as fish food, but by their growth and decay, organic
material is released into the water. This promotes the growth of water
bacteria and the smaller animals which are the food of fish. The role of
organic fertilizers is more direct. Such material is available for immediate
bacterial decay and may even serve directly as food for some aquatic
animals. The application of either type of fertilizer usually results in an
increase in both plant plankton and fish crops (Smith and Swingle 1940).
Because plankton and fish production are known to be related in ponds,
the question arises as to whether or not the elimination of part of the
plankton crop with copper sulphate will seriously affect fish production.
To answer this question, it is necessary to consider a more basic one. Is
there a direct and proportionate relationship between plant and animal
production in waters?
Huff (1923) found that the growth of the plant plankton crop or its
reduction with copper sulphate had no effect on the population trends of
microscopic animals in Lake Vadnais near St. Paul. Pennak (1946) in
reviewing his work on the plankton of Colorado lakes concludes that “a
relatively low plankton crop .. . may support populations of grazers which
range from very low to very high and that dense phytoplankton popula-
tions are not necessarily associated with dense populations of grazers.”
Similarly, in natural Minnesota ponds used for the rearing of pike-perch
from fry to fingerling size, a concentration of nutrients was found above
which additional natural fertility, and presumably the amount of organic
matter produced by that fertility, did not increase the yield. In a series
of such ponds, having an excess of calcium and nitrogen, those in which
total phosphorus concentrations were between .02 and .05 ppm yielded an
average 11.4 pounds of fingerlings per acre; those within a total phosphorus
range of .051 -.1 ppm yielded 71.2 pounds per acre; those within a range
of .11-.2 yielded 65.5 pounds, and those with a total phosphorus concen-
tration greater than .21 yielded at the average rate of 67.8 pounds per acre
(Moyle 1949). It appears, therefore, that above a certain optimum level,
added fertility and the production of organic material by algal growth
does not greatly increase the production of aquatic animals. Above an
optimum level, it is likely that other biological and spatial factors become
more important than basic food supply.
The main purpose of pond fertilization is to make certain that enough
organic material is present for maximum fish production. To be sure of
this, ponds are fertilized heavily enough to raise an excess of algae. In
algal control with copper sulphate, the reverse is accomplished. Excess
organic producing power as represented by algae is removed by chemical
COPPER SULPHATE IN ALGAL CONTROL AND IMPLICATIONS 83
treatment. In the Fairmont lakes, it appears that the removal of such
an excess has had little effect on the yield of rough fish. Expressed another
way, organic production has not been reduced below, or much below, the
critical optimum level despite a long history of copper sulphate treatment.
There are several reasons why such a result might be expected. First,
waters which have objectionable algal crops are very fertile and produce
an abundance of other aquatic life besides specific bloom formers. Second,
destruction of an algal crop by copper sulphate does not destroy the organic
material that this crop represents. The organic material is released into
the water upon decay of the algal cells. Often this decay is accompanied
by a great bacterial increase (Whipple 1927). Third, usually following a
copper sulphate treatment, rapid growth is made by copper tolerant forms
which were not killed. After the destruction of a heavy Aphanizomenon
bloom in Hall Lake on June 3, 1946, the population of planctonic diatoms
and green algae rose from 300,000 to 41,000,000 per 100 liters in 5 days.
During this same period, the population of animal plankters and euglenoids
rose slightly from 34,000 to 40,000 per 100 liters (Moyle and Wilson 1946).
Schoenfeld (1947) concludes that since copper precipitates from hard
water as insoluble copper carbonate, this salt accumulates on the bottom
to the detriment of fish-food animals living there. This conclusion is evi-
dently based on the work of Nichols et al. (1946) on the accumulation of
copper in the treated lakes at Madison, Wisconsin, and the statement of
Hasler (1947) that Lake Monona, a treated lake of this chain, had 800
bottom fauna organisms per square meter in contrast to 9,000 for untreated
Lake Mendota.
It is well known that copper carbonate is poisonous to snails and its
toxicity is utilized for controlling swimmer’s itch. McMullen (1941) found
that when high concentrations of copper sulphate or mixtures of copper
sulphate and copper carbonate were applied to the shallow waters in Michi-
gan, “crayfish, leeches, tubificides and insect larvae were usually killed.”
He also notes that the use of 20 ppm copper sulphate resulted in the ac-
cumulation of 78.6 mg of copper per square foot of bottom 4 hours after
treatment.
It is certain from this and other similar observations by McMullen
and also from the experimental work of Whipple (1927) that following
a copper sulphate treatment, copper does precipitate onto the bottom mud.
It is also certain that high concentrations of precipitated copper are
poisonous to aquatic invertebrates. There is, however, an important ques-
tion to be answered. Do these precipitated copper compounds remain
insoluble and accumulate on the lake bottom to such an extent that pro-
duction of fish food is affected?
Whipple (1927) noted that copper carbonate may be decomposed into
copper “hydrate” (hydroxide?) and carbonic acid, and that although the
hydrate is insoluble, the carbonate is slightly soluble in the presence of
carbonic acid. Since carbon dioxide is being continually generated from
bottom muds, it is likely that at least some of the precipitated copper car-
84 LIMNOLOGY, WATER SUPPLY AND WASTE DISPOSAL
bonate goes into solution again. McMullen (1941), when eradicating
snails in a hard-water Michigan lake, found that there were 75.6 mg of
copper per square foot of bottom 4 hours after treatment; 30 mg at the
end of 24 hours, and 4.8 mg at the end of 54 hours. Whipple cites a con-
clusion of Hale (without exact reference) that at least during the winter
months all copper fed into the New York water supply came through the
distributing system. Conversely, he notes another case where 3% copper
was reported in the bottom mud of a reservoir that had been treated.
The most conclusive evidence on the accumulation of copper in the
bottom muds of treated lakes is that of Nichols et al. (1946) who analyzed
muds from three Wisconsin lakes with a long history of copper sulphate
treatment. In the treated lakes a range of 18 to 1093 mg of copper per
kilogram of bottom mud was found in Lake Menona; 18 to 595 mg in
Lake Waubesa and 18 to 595 mg in Lake Kegonsa. In contrast, untreated
Lake Mendota showed a range of 32 to 135 mg of copper per kilogram of
bottom mud. These workers conclude that “. . . 7t appears that by far
the greatest amount of that copper applied remains as a deposit in the
mud of the lake.”
The amount of siltation is also important. In lakes, such as those
of the Fairmont chain, which are continually receiving silt from adjacent
land, any copper precipitated to the bottom would be buried and its possi-
ble toxic effect on bottom fauna thereby greatly lessened.
ALGAL CONTROL AND THE GROWTH OF LARGER AQUATIC PLANTS
Larger aquatic plants are quite tolerant to copper sulphate and there
is no record of injury to them from algal control measures in Minnesota.
The higher algae are more susceptible than the aquatic seed plants and
the growth of such forms as Chara and Hydrodictyon has been controlled
with copper sulphate in fish ponds. Greater concentrations are necessary
than those ordinarily used for plankton algae (Surber 1948; O’Donnell
1945). In reviewing the literature on the effect of copper on terrestrial
seed plants, Miller (1931 p. 284) states that although copper is usually
toxic, low concentrations of .02 to .2 ppm “not only increased the length
of life of various plants but also their dry weight.”
Generally, there is an inverse relationship between plankton produc-
tion and that of larger aquatic plants. Minnesota lakes with little plank-
ton may have aquatic weeds to a depth of 25 feet. In those with moderate
plankton production, the littoral zone usually extends to about 15 feet
and in those with a heavy algal bloom there are often few weeds beyond a
depth of 4 feet. The production of a heavy plankton crop by fertilization
has been found to be an effective way to control weed growth in fish ponds
(Smith and Swingle 1941). Conversely, plankton production may be
limited by robust growth of the larger aquatic plants. Observations along
this line have been made by Kofoid (1903) and more recently by Bennett
(1943) who recommends the elimination of larger aquatic plants from fish
COPPER SULPHATE IN ALGAL CONTROL AND IMPLICATIONS 85
ponds because “they take up nutrient materials and light that would
otherwise produce algae.”
A few general observations have been made on algal control and the
growth of larger aquatic plants. Huff (1923) notes that concurrent with
algal control in Lake Vadnais there was “cutting and removal of great
quantities of submerged vegetation each year.” Domogalla (1935) states
that during 11 years of treatment of Lake Monona “weeds have grown
luxuriantly in 18 feet of water’ and flourished despite the use of a
weed cutting machine.
It appears that control of plankton algae with copper sulphate can
be expected to have little or no detrimental effect on larger aquatic plants
and may even increase their growth.
ACQUIRED TOLERANCE OF ALGAE TO COPPER SULPHATE
Hale (1942) and Whipple (1927) are both definitely of the opinion
that algae do not acquire a tolerance to copper. However, acclimatization
of other microorganisms to copper and similar heavy metals is fairly well
known (Heilbrun 1987, p. 294). -
In the Fairmont lakes, Aphanizomenon seems to have acquired an
increased tolerance to copper as a result of 26 years of treatment. These
lakes were first treated in 1921 by Huff (1922). He carefully noted the
kinds of algae present, the concentrations of copper sulphate used and the
results. The concentrations used for successful control in the 4 lakes at
that time were: Amber, .15 ppm; Hall, .14 ppm; Budd, .20 ppm; and
Sisseton, .24 ppm. In the period 1943-46 much higher concentrations were
necessary to obtain the same results; the average of treatments in these
years being Amber, .35 ppm; Hall, .73 ppm; Budd, .80 ppm; and Sisseton,
.50 ppm. Two to five times as much copper sulphate must now be used as
was necessary in 1921.
The high concentrations used in later years on the Fairmont lakes
were necessary and not due to calculation or judgment errors of the Fair-
mont Water Department. Moyle and Wilson (1946) supervised treatment
of Hall Lake with .5 ppm and achieved only partial success in eliminating
Aphanizomenon—a reduction of 1,200,000,000 to 21,800,000 filaments per
100 liters 5 days after treatment. This alga made a rapid recovery and
it was soon necessary to treat the lake again. In both 1921 and 1946 the
boat and burlap bag method of application was used.
Two other hard-water Minnesota lakes with Aphanizomenon blooms
were treated for the first time in the summer of 1947. No filaments were
found following treatments with .8 ppm in Little Elk Lake, Sherburne
County, and no return of the bloom for a month was noted in Spring Lake,
Scott County, which was treated with .11 ppm.
SUMMARY
Although much work has been done on the toxicity of copper sulphate
to different aquatic plants and animals, little consideration has been given
86 LIMNOLOGY, WATER SUPPLY AND WASTE DISPOSAL
to the effect of its continued use as an algicide on the productivity of
waters. In Minnesota, 4 lakes have been regularly treated with copper sul-
phate for 26 years. The average rough fish yield from these lakes for the
last 24 years is slightly greater than that of 5 adjacent untreated lakes.
In the treated lakes, the blue-green alga, Aphanizomenon, seems to have
acquired an increased tolerance to copper as a result of the 26 years of
treatment. From theoretical considerations and the few data available, it
appears that algal control with copper sulphate is not detrimental and may
even favor the growth of aquatic seed plants. It is also likely that ordinary
algal control has little effect on the production of plankton animals.
Whether or not copper accumulates in the bottom muds to the extent of
being toxic to the bottom fauna is at present uncertain.
REFERENCES CITED
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investigations, 1938-1942. JIl. Nat. Hist. Survey Bul., 22: 357-376.
Domocaia, B. 1935. Eleven years of chemical treatment of the Madison lakes:—its
effect on fish and fish foods. Amer. Fisheries Soc. Trans., 65: 115-121.
Eis, M. M. 1937. Detection and measurement of stream pollution. U. S. Bur. Fisheries
Bul., 22, 48: 365-437.
Fircn, C. P., Bisuor, L. M., Boyp, W. L., Gortner, R. A., Roczrs, C. F. anp TILDEN,
J. E. 1934. “Water Bloom” as a cause of poisoning in domestic animals. Cornell
Vet., 24, No. 1: 31-40.
Hate, F. E. 1942. In The Use of Copper Sulphate in Control of Microscopic Organisms.
Phelps Dodge Refining Co., New York.
Haster, A. D. 1947. The case against spraying copper sulphate in lakes. Wzs. Acad. Scv.,
Arts, Letters. In press.
Heitprun, L. V. 1937. In An Outline of General Physiology. W. B. Saunders Co.
Hiner, L. E. 1943. A creel census of Minnesota lakes, 1938-1942. Minn. Dept. Conserv.,
Bur. Fisheries Res. Invest. Rpt. No. 44.
Hurr, N. L. 1922. Copper sulphate treatment for preventing algae growths in lakes and
reservoirs. Water Works News, pp. 65-72.
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Vadnais Lake. Minn. Univ. Studies Biol. Sci., No. 4: 185-198.
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notes upon the hydrography of the Illinois River and its basin. Part I. Quantita-
tive investigations and general results. Jl. Nat. Hist. Survey Bul., 6: 95-628.
McMotten, D. B. 1941. Methods used in the control of schistosome dermatitis in
Michigan. Symposium on Hydrobiology, Wis. Univ. Press, pp. 379-388.
Marsu, M. C. anp Rosinson, R. K. 1910. The treatment of‘fish-cultural waters for the
removal of algae. Fourth Internatl. Fisheries Cong. Proc. 1908, Part II: 871-890
(Pub. by U. S. Bur. Fisheries, Bul., 1908).
Muuer, EH. C. 1931. In Plant Physiology. McGraw-Hill, New York.
Moorz, G. T. anp KetiermMan, K. F. 1905. Copper as an algicide and disinfectant in
water supplies. U.S. Dept. Agr. Bur. Plant Indus. Bul. 76: 1-55.
Moytz, J. B. 1949. Some indices of lake productivity. Amer. Fisheries Soc. Trans. In
press.
Moyts, J. B. anv Witson, J. N. 1946. Report on the use of copper sulphate for control-
ling blue-green algae in Hall Lake (2-83) and connected water supply lakes in
Martin County. Minn. Dept. Conserv. and Health.
Nicuots, M. S., Henxet, T. anp McNatu, D. 1946. Copper in lake muds from lakes
of the Madison area. Wis. Acad. Sci., Arts, Letters, Trans., 38: 333-350.
O’DonneLL, D. J. 1945. Control of Hydrodictyon reticulatum in small ponds. Amer.
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COPPER SULPHATE IN ALGAL CONTROL AND IMPLICATIONS 87
Pennak, R. W. 1946. The dynamics of fresh-water plankton populations. Ecol. Monog.,
16: 339-356, Oct.
ScHOENFELD, C. 1947. Don’t let ’em spray. Field and Stream, 52, No. 4: 46, 79, 80, 81,
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Smrrn, E. V. anp Swinatz, H. S. 1940. Effect of organic and inorganic fertilizers on
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. 1941. The use of fertilizer for controlling the pondweed, Najas guadalupen-
sis (Spreng.) Morong. 6th North Amer. Wildlife Conf. Trans., pp. 245-251.
Smitu, M. W. 1935. The use of copper sulphate for eradicating the predatory fish popu-
lation of a lake. Amer. Fisheries Soc. Trans. 65: 101-113.
Surser, E. 1943. Weed control in hard-water ponds with copper sulphate and sodium
arsenate (arsenite). 8th North Amer. Wildlife Conf. Trans., pp. 132-140.
Wurtz, G. C. 1927. In Microscopy of Drinking Water. 4th edit. rev. by Fair and
Whipple. John Wiley and Sons. New York.
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