7 Fé 563 Florida Volume 38 Fall, 1975 No. 4 ACADEMY SYMP LAND SPREADING OF SECOND Lo LECT eae eee Rudy J. Wodzinski 193 Chemical, Physical and Biological Composition wetgeea! Sccondary Effluents.........0.........2.0:2.0-- Rudy J. Wodzinski 194 Virus Considerations in Land Disposal of Sewage Effluents and Sludge ...................... F. M. Wellings, A. L. Lewis, C. W. Mountain and L. M. Stark 202 An Overview— Wastewater Treatment Disposal Systems Utilizing Land Application .............0000000.0.. Russell L. Wright 207 Effluent Irrigation as a Physicochemical LE TET 66 0) 1 o) 00 Allen R. Overman 215 Land-Spreading of Secondary Effluents........0..000.00. cee. G. J. Thabaraj 222 Re MMMMRREOM MM NC ACCUINY 22.0 seco e se foc oce seks vc oagacgsteestdenrsecenscitee Peter P. Baljet 228 Se NN RONNIE 2172, ole aaa aga scant dnc vawbldne ateend oo 232 NINN RCI MCC 5 Se sce hes 8 e801 ae (ae Soe lacs asvnssvseedeubsueevasndvoden veer’ 233 Formulation of the Energy Equation A 291 Ce ee Pieter S. Dubbelday 234 *Copies of this issue may be obtained for $5.00 postpaid from the Academy offices, 810 East Rollins Street, Orlando, Florida 32803. QUARTERLY JOURNAL OF THE FLORIDA ACADEMY OF SCIENCES FLORIDA SCIENTIST QUARTERLY JOURNAL OF THE FLORIDA ACADEMY OF SCIENCES Copyright © by the Florida Academy of Sciences, Inc. 1975 Editor: Harvey A. Miller Department of Biological Sciences Florida Technological University Orlando, Florida 32816 The Fiorina Scientist is published quarterly by the Florida Academy of Sciences, Inc., a non-profit scientific and educational association. Membership is open to individuals or institutions interested in supporting science in its broadest sense. Applications may be obtained from the Treasurer. Both individual and institutional members receive a subscription to the FLoripa Scientist. Direct subscription is available at $10.00 per calendar year. Original articles containing new knowledge, or new interpretation of knowledge, are welcomed in any field of Science as represented by the sections of the Academy, viz., Biological Sciences, Conservation, Earth and Planetary Sciences, Medical Sciences, Physical Sciences, Science Teaching, and Social Sciences. Also, contributions will be considered which present new applications of scientific knowledge to practical problems within fields of interest to the Academy. Articles must not duplicate in any substantial way material that is published elsewhere. Contributions from members of the Academy may be given priority. Instructions for preparation of manuscripts are inside the back cover. Officers for 1975 FLORIDA ACADEMY OF SCIENCES Founded 1936 President: Dr. WiLL1AM H. Tarr Treasurer: Dr. ANTHONY F. WALSH Division of Research Microbiology Department University of South Florida Orange Memorial Hospital Tampa, Florida 33620 Orlando, Florida 32806 President-Elect: Dr. Patrick J. GLEASON Editor: Dk. Harvey A. MILLER 9809 W. Churchill Court Department of Biological Sciences West Palm Beach, Florida 33401 Florida Technological University Orlando, Florida 32816 Secretary: Dr. Invinc G. Foster Department of Physics Program Chairman: Dr. JosEpH MuLSON Eckerd College Department of Physics St. Petersburg, Florida 33733 Rollins College Winter Park, Florida 32789 Published by the Florida Academy of Sciences 810 East Rollins Street Orlando, Florida 32803 Printed by the Storter Printing Company Gainesville, Florida Florida Scientist QUARTERLY JOURNAL OF THE FLORIDA ACADEMY OF SCIENCES Harvey A. Miller, Editor Vol. 38 | Fall, 1975 No. 4 Academy Symposium LAND SPREADING OF SECONDARY EFFLUENT Rupy J. Wopzinsk1, Chairman Gordon J. Barnett Professor of Environmental Sciences, Florida Technological University, Orlando, Florida 32816 THE THEME selected for the Academy's Symposium at the 1975 ANNUAL MEETING OF THE FLoripA ACADEMY OF SCIENCES was Land Spreading of Second- ary Effluent. All other activities were halted to focus attention on the six papers presented to summarize this complex subject. Research results were presented by professional microbiologists, geologists, virologists, agricultural engineers, chemical engineers and hydrologists. In addition, some viewpoints were pre- sented which are representative for state and federal agencies charged with the regulatory aspects of the landspreading of secondary effluents. It is most timely that special attention be drawn to this important alterna- tive for disposal of sewage effluents. Florida, with its unusual climate and geo- logical constitution, presents unique situations for land spreading. We are fortu- nate today to have in Florida individuals who have studied the effects of land- spreading for a number of years. The summaries of their data on the effects of landspread on the environment presented are worthy of careful study and atten- tion by scientists, professional consultants, and responsible officials in the sev- eral levels of government. The need for a multidisciplinary approach is empha- sized for this complex problem that affects the fragile environment of Florida. Hopefully, the exchange of information and ideas which occurred at the Sym- posium and which will occur as a result of this publication will spur scientists in the State of Florida as well as in the United States to develop techniques and regulations for the landspreading of secondary effluents which will achieve de- sirable water quality goals and protect the health of its residents. Academy Symposium CHEMICAL, PHYSICAL AND BIOLOGICAL COMPOSITION OF “TYPICAL” SECONDARY EFFLUENTS R. J. WopzinskI Department of Biological Sciences, Florida Technological University, Orlando, Florida 32816 Asstract: Chemical, physical and biological composition of the secondary effluents from mu- nicipal treatment plants is reviewed. IT Is IMPOSSIBLE to formulate a quantitative definition of a secondary efflu- ent which will serve in all situations. Typically, a secondary effluent is the dis- charge from a sewage plant after secondary treatment of water wastes. This im- plies that waste water has been processed by preliminary treatment, i.e. pre- chlorination in most cases, removal of grit and passage through a communitor; and by secondary treatment, i.e. biological oxidation of the organic matter, in an activated sludge tank or contact aerator followed by clarification. In many waste water plants in Florida secondary treatment is followed by retention of the effluent in holding ponds for 1-7 days. Most plants chlorinate the effluent from the holding pond. The physical, chemical and biological composition of secondary effluents will vary with 1) the type of influent, i.e. residential, industrial or combined residential-industrial; 2) the type of treatment facility; and 3) the competence of the personnel operating the facility. These variables are difficult to control and result in a secondary effluent which differs from treatment plant to treatment plant and from the same treatment plant on different days. PHYSICAL AND CHEMICAL ComposiTIoN—As part of its mission to enforce state and federal water quality standards on parties who discharge effluents, Orange County Pollution Control monitors the effluent discharge of waste water treatment facilities in Orange County, Florida. They provided raw data which are the basis of the calculated values in Tables 1, 2, 3, and 5. Analytical data on effluents from four sewage plants in the county were col- lected during 1973 and 1974 on a monthly basis. These plants are secondary treatment facilities and all have holding ponds. They receive diverse influents ranging from strictly residential wastes to combined residential wastes plus un- digested residues and wastes from such sources as septic tanks, recreational ve- hicles, citrus processing, potato chip processing, dairy processing, or soft drink processing. Regular sampling times were used at the various sites where values were established for all parameters listed in the tables. If data were incomplete they were not utilized. Means were drawn from 38 sets of data (Table 1). The avg dissolved oxygen concentration in the effluent for the four plants in the 2 yr span was 5.8 mg/l. The temperature varied from 20° to 29° C during No. 4, 1975] WODZINSKI—COMPOSITION OF SECONDARY EFFLUENTS 195 these studies. The ranges of dissolved oxygen are as important as the avg value. The range was from 0.0 to 24.4 mg/l. The 0.0 value indicates that at least one plant on one occasion during the sampling period had inadequate treatment and was discharging effluent that was not completely oxidized. The 24.4 mg/] value indicates that the holding pond had a high concentration of algae that produced enough oxygen to supersaturate the effluent. TaBLe |. The avg values for the physical and chemical data of secondary effluents of 4 sewage plants in Orange County, Florida, during 1973-74. mg/1 x! Range Dissolved Oxygen 5.8 0.0— 24.4 BOD, 9.6 L1— 46 COD> 42.7 11.8— 74.9 Hardness as CaCO, 94.1 590.9—162 Total Alkalinity as CaCO, 113.1 39 —199 Total Acidity as CaCO, 15.9 7 — 30.8 Total Solids 326 109 —577 Suspended Solids 9 0.0— 22.5 pH 7.3 6.8— 89 'Values are the averages of 38 determinations. *Values are the averages of 15 determinations. Raw data courtesy of Orange County Pollution Control. The avg BOD, and COD levels from the four plants (9.6 mg/] and 42.7 mg/1) indicates good overall performance. However, the high range values; BOD, equal to 46 mg/l and COD equal to 74.9 mg/], indicates once again that at least on one occasion a plant was not functioning properly. The data reported here reflect typical operation of well run waste water fa- cilities. The avg performance of facilities is good but poor treatment does occur sometimes. In a land spreading operation, effluents which have been poorly treated will be spread unless precautions to prevent the spreading are enforced. Values for hardness, total alkalinity, total acidity and other values for the metallic cations are largely dependent on the inorganic composition of the water supply. These values have regional significance. When effluents are spread they become of interest to agronomists for cropping studies and to geologists if they should percolate through soil to the aquifer or are drained into navigable waters. The values in the tables are listed as mg/l. These can be converted to lbs/ acre/in. of effluent applied. Each mg/1 corresponds to 0.227 Ibs/acre/in. (=0.1 kg/ha/cm) of effluent applied. Levels of sodium, calcium, magnesium, potassium, iron, copper and chlorine present in sewage effluents are noted in Table 2. The avg turbidity of the efflu- ents monitored was 11 Jackson Units and the avg conductivity 510 micro mho. The avg values for phosphorus and nitrogen are shown in Table 3. Levels of metallic cations, phosphorus, and nitrogen must be correlated to the ion ex- 196 FLORIDA SCIENTIST [Vol. 38 change capacity of a particular soil, the microbial transformation which might occur, and the hydrology to determine whether the materials will eventually move vertically to the permanent aquifer or laterally to streams. TaBLE 2. The avg values for the physical and chemical data of secondary effluents of 4 sewage plants in Orange County, Florida, during 1973-74. mg/l x’ Range Sodium 42.2 21.5 — 65 Calcium 23.6 12.4 — 44.8 Magnesium 8.39 6.35— 12.2 Potassium 9.65 6.55— 19.6 Iron (0.3)? 0.18 0.0 — 0.70 Copper (1.0)? 0.03 0.0 — 0.07 Chlorine (250)? 43 6 — 62 Turbidity (J.T.U.) 11 2 — 44 Conductivity micro mho 510 235 —990 'Values are the averages of 38 determinations. Values in ( ) are Public Health Drinking Water Standards (1962). Raw data courtesy of Orange County Pollution Control. The presence of organic compounds (Table 4) in secondary effluents has been reviewed by Hunter (1974); and Hunter and Kotalik (1974). Low concentrations of the branched and unbranched fatty acids, and the sterols coprastanol and cholesterol were detected by Murtaugh and Bunch (1967). O'Shea and Bunch (1965) found uric acid. Kahn and Wayman (1964) detected the amino acids leu- TABLE 3. The avg values for the physical and chemical data of secondary effluents of 4 sewage plants in Orange County, Florida, during 1973-74. mg/| x! Range Phosphorous Ortho 5.91 2.0 —11.59 Poly 0.82 0.0 —11 Total 6.68 3.11—13 Nitrogen NO, 0.04 0.0 — 0.132 NO,(45)? 1.65 0.04— 6.55 NH, 5.42 0.0 —24 Organic 2.31 0.8 —11.84 Total 9.8 1.65—29.57 'Values are the averages of 38 determinations. Values in ( ) are Public Health Drinking Water Standards (1962). Raw data courtesy of Orange County Pollution Control. No. 4, 1975] WODZINSKI—COMPOSITION OF SECONDARY EFFLUENTS 197 TaBLeE 4. Organic compounds detected in secondary effluents. ComMPouND CONCENTRATION mg/ml Formic acid’ 9.1 x 10-’ Acetic acid!’ 1.3 x 10-4 Propionic acid' 1.37 x 10° Isobutyric acid’ 2.65 X 10-° Butyric acid' 3.07 xX 10-* Isovaleric acid’ 7.34 X 10~° Valeric acid’ Sax 1052 Caproic acid’ 4.79 x 10°’ Uric acid? 5-12 x 10°° Coprostanol' 8 x 10° Cholesterol’ ; 15 x 10°° Pyrene® 0.4-1.0 x 10°° Leucine* ) Valine* 5 'Murtaugh and Bunch (1967). 2O’Shea and Bunch (1965). ‘Wedgewood (1952). ‘Kahn and Wayman (1964). cine and valine. Others have identified gallic, citric and perhaps lactic acid and the amino acids serine, glycine, aspartic acid, glutamic acid and threonine. The listing of organic compounds in sewage effluents is incomplete. Recent publicity on the studies on industrial effluents in New Orleans in which chlorination has been implicated as causing the halogenation of aromatic compounds to produce known carcinogens has catalyzed renewed emphasis on survey of organic com- pounds in wastewater. We can expect more definitive data on the organic con- tent of effluents. BIOLOGICAL CONTENT OF SECONDARY EFFLUENTS—The biological content of secondary effluent varies. If an effluent is chlorinated and the free HOCI con- centration is maintained for an adequate period of time the biological content will be nil. It should be emphasized that this is true only if the secondary efflu- ent has a very low concentration of suspended solids and therefore low turbidity. High concentrations of suspended material and high turbidity increase the chlo- rine demand of the effluent and affords protection to bacteria and virus which are either entrapped in the particulate matter or adsorbed to it. High concen- trations of suspended material enhance the possibility for providing inadequate chlorine to achieve disinfection. The ranges of total and fecal coliforms/100 ml are listed in Table 5. The sewage treatment facilities surveyed did not chlorinate effluents during 1973 but did chlorinate the effluents in 1974. This accounts for the wide range in the numbers of microorganisms detected. Most investigators who conduct surveys on wastewaters restrict sampling to indicators of fecal pollution. However, Pike and Carrington (1972) performed an excellent survey on sewage effluents and solids utilizing microbial numerical taxonomy (Table 6). They surveyed the microbial population for 29 different 198 FLORIDA SCIENTIST [Vol. 38 TaBLe 5. Bacteriological analysis of secondary effluents of 4 sewage plants in Orange County, Florida, during 1973-74. Range' Total Coliforms/ 100ml 8.5 X 10°-3.0 x 10° Fecal Coliforms/ 100ml 2.0 X 10—3.30 x 10° Fecal Streptococci/ 100ml 2.2 x 10-15 X 10° Total plate count/ml 20 xX 10—7.5 xX 10° 'Values from 38 analyses. Raw data courtesy of Orange County Pollution Control. characteristics. It is apparent that the numbers of microorganisms is much higher per g of suspended solids than per ml of sewage effluent. Data they reported does not identify the organisms into specific genera. The methods used indicate the number of microorganisms which may possess more than one activity. These data do reflect the biochemical capacity of the efflu- ent and the types of reactions which would occur if substrate for the reaction is present in the effluent or the soil on which it is spread. Usually microbiologists concede that inoculating a natural environment such as soil with a specific microorganism does not guarantee that the newly introduced microorganism will a) survive or b) reproduce unless the environment contains the same physical and chemical characteristics which will allow the newly introduced micro- organisms to out-compete the indigenous flora. However, few studies exist in which not only microorganisms are introduced into a natural environment but also substrate. For secondary effluent, we can cite a specific example—NO,, NO.,, and NH, are added when a secondary effluent is applied to soil. If an unchlori- nated effluent is added 7.1 X 10° nitrate reducers/ml] and 95 Nitrosomes spp/ml are added (Table 6) as well. Both types of organisms are important in the inter- conversions of nitrogen. Since substrate as well as microorganisms are added it is possible that an ecological upset might occur in the soil. Dr. Reichenbaugh discussed nitrification in soil during land spreading. Secondary sewage effluents also contain viruses. Grabow (1968) has listed over 100 serotypes of human enteric viruses which have been detected in sewage. Culp, et al. (1971) reported the presence of virus in secondary effluents at the South Lake Tahoe Plant (Table 7). Dr. Wellings dealt with viral aspects of efflu- ent disposal in her report in this symposium. Public health aspects of the spreading of secondary sewage effluents has caused concern. Drs. Thabaraj and Wright reported some of the state and federal standards which were prompted by this concern in this symposium. Approximate numbers of disease organisms and indicators used for disease organisms in secondary effluents are listed in Table 8. Numerous investigators have attempted to correlate the numbers of coliphage with the number of enteric virus in secondary effluent. Wolf, et al. (1974) detected 2.39 to 10* PFU coli- phage/ml. Kott, et al. (1974) reported 1.0 X 10? coliforms/coliphage and 1.0 X 10° coliphages/human enteric virus in secondary effluents. The values agree within a factor of five. No. 4, 1975] WODZINSKI—COMPOSITION OF SECONDARY EFFLUENTS 199 TaBLE 6. Numbers and kinds of bacteria isolated from effluents and effluent suspended solids during high rate activated sludge treatment in England.' Population/g Population/ml suspended Bacteria effluent solids Total bacteria 4.8 x 10’ 3:0 DAO? Nitrate reducers 7.1 X 10° 4.3 * 10'° Viable bacteria 1.5 x 10° 1.0 x 10! Indoxy] Butyrate” 4.0 x 10° 2 OE Catalase positive 3.1 x 10° 2.0 x 10” Anaerobes 2.8 Xx 10° 1.8 x 10'° Glucose, Aerobic acid 2.3 X 10° 15) Culp, et al. 1971. ent samples from different treatment plants and sources, The ratio should be used only as an approximation. The physical, chemical and biological composition of secondary effluents varies among different treatment plants and within the same treatment plant on different days. This variation must be considered in studies of secondary sewage effluents. TABLE 8. Approximations of the relative numbers of indicator and disease organisms in secondary effluents. WoLrF, ET AL. (1974). 2.39—3.44 x 10‘ Pfu of coliphage/ml. Kort, ET AL. (1974). 1.0 X 10’ Coliforms/coliphage 1.0 X 10° Coliphages/human enteric virus Buras (1974). 2.0 X 10° Coliforms/human enteric virus in secondary effluent 2.0 X 10* Coliforms/human enteric virus in raw sewage Kortt anv Kotr (1967). 7 X 10-°/Entamoeba histolytica/ml] and 22 X 10-* Entamoeba coli/ml McCoy (1971). Calculations of his data indicate 3.1—9.1 x 10% E. coli/Salmonella SUMMARY In unchlorinated secondary effluents the approximate numbers of organisms/ml is: Coliforms + Coliphage « Humanentericvirus + Salmonella + Entamoeba 3.4 10° ¢ 34% 10° © 3.4 x 10? © 1K 10?) ~ 722s ACKNOWLEDGMENTS—I wish to thank Mr. Terry Stoddart and Mr. John Bate- man of the Orange County Pollution Control for making the Orange County Data on secondary effluents available for this paper. No. 4, 1975] WODZINSKI—COMPOSITION OF SECONDARY EFFLUENTS 201 LITERATURE CITED Buras, N. 1974. Recovery of viruses from waste-water effluents by the direct inoculation method. Water Res. 8:19-22. Cup, R. L., D. R. Evans, anv J. C. Wixtson. 1971. Advanced Waste Water Treatment as Prac- ticed at South Tahoe. Water Pollution Contr. Res. Ser. Environ. Prot. Agency, Water Qual. Off. 17010 ELQO 8/71. Washington, D.C. Grasow, W. O. K. 1968. The virology of waste water treatment. Water Res. 2:675-701. Hunter, J. V. 1971. Origins of organics from artificial contamination. Pp. 51-94. In Faust, S. J., AND J. V. HunTER (eds.) Organic Compounds in Aquatic Environments. Marcel Dekker Inc. New York. AND T. A. Kora.ik. 1974. Chemical and biological quality of sewage effluents. Pp. 6- 27. In Soprer, W. E., anv L. T. Karpos (eds.) Conference on Recycling Treated Municipal Wastewater Through Forest and Cropland. Environ. Prot. Tech. Ser. Office of Research and Development. U.S. Environmental Protection Agency. EPA-660/2-74-003. Washington, D.C. Kort, Y., N. Roze, S. SPERBER, AND N. Betzer. 1974. Bacteriophages as viral pollution indicators. Water Res. 8:165-171. Kort, H., anp Y. Kort. 1967. Detectability and viability of Endamoeba histolytica cysts in sewage effluents. Water & Sewage Works 114:177-180. Kaun, L., anp C. Wayman. 1964. Amino acids in raw sewage and sewage effluents. J. Water Pollut. Contr. Fed. 36:1368-1371. McCoy, J. H. 1971. Sewage pollution of natural waters. Pp. 33-50. In Syxes, G., anp F. A. SKINNER (eds.) Microbial Aspects of Pollution. Society Applied Bacteriology Symposium Ser. No. 1. Academic Press. London. Morraucu, J. J., anD R. L. Buncu. 1967. Sterols as a measure of fecal pollution. J. Water Pollut. Contr. Fed. 39:404-409. O'SHEA, J., AND R. L. Buncu. 1965. Uric acid as a pollution indicator. J. Water Pollut. Contr. Fed. 37:1444-1446. Pixe, E. B., anp E. G. Carrincton. 1972. Recent developments in the study of bacteria in the acti- vated sludge process. J. Inst. Water Pollut. Contr. 6:1-24. Wo r, H. W., R. S. SAFFERMAN, A. R. Mixson, anp C. E. Strincer. 1974. Virus inactivation during tertiary treatment. J. Amer. Water Works Assn. 66:526-531. Florida Sci. 38(4):194-201. 1975. Academy Symposium VIRUS CONSIDERATION IN LAND DISPOSAL OF SEWAGE EFFLUENTS AND SLUDGE F. M. We.uincs, A. L. LEwis, C. W. MounTaIn AND L. M. STARK Epidemiology Research Center, Department of Health and Rehabilitative Services, State of Florida, Division of Health, 4000 West Buffalo Avenue, Tampa, Florida 33614 ApstRACT: As populations increase, disposal of man’s biological wastes poses increasing threats to man’s health through contamination of potable water sources with chemicals and pathogenic orga- nisms. We have addressed the latter and more specifically, the virus problem. Data accrued in labora- tories and in the field related to virus survival in the terrestrial environment are reviewed. AS POPULATIONS INCREASE, disposal of man’s biological wastes poses increas- ing threats to his health through chemical and biological contamination of po- table water sources, particularly today when land disposal of these wastes is becoming more widespread. Many publications have dealt with chemical and microbiological aspects of land disposal of sewage effluents under field condi- tions. However, there is a dearth of information related to viruses under the same circumstances. Laboratory data (Drewry and Eliassen, 1968; Lefler and Kott, 1974; Young and Burbank, 1973) have indicated that virus may or may not be trapped in the upper few inches of the soil, depending on the type of soil tested. Unfortunately, most of these studies were carried out in sterilized soil-packed columns which in no way represent conditions encountered under natural situations. A recent laboratory study by Lefler and Kott (1974) in Haifa showed that repeated wash- ings of sand to which poliovirus had been adsorbed continued to yield virus through repeated washings. Most virus was eluted in the first wash but some could still be demonstrated in the 10th wash water. They also showed that polio- virus survived for 77 days in dry sand and 91 days in moist sand. When the tem- perature was reduced to 20°C, 20% of the virus survived for 175 days. Again, these sands had been sterilized before virus was added. The earliest evidence for virus survival in the terrestrial environment re- sulted from epidemiological studies of waterborne infectious hepatitis out- breaks. Many studies have indicated that passage through soils of virus laden cesspool and septic tank seepage have resulted in contamination of potable water sources (Eliassen and Cummings, 1949; Hallgren, 1942; Mosley, 1959; Tucker, et al., 1954). More direct evidence for virus survival and movement in soils was the iso- lation by Mack et al. (1972) of poliovirus type 2 from 50 gal of water drawn from a 100 ft deep well located more than 300 ft from the edge of a wastewater drain field. This isolation was made during the investigation of a gastroenteritis out- break in patrons of a restaurant using the well water. No. 4, 1975] WELLINGS ET AL.—VIRUS IN SEWAGE EFFLUENT 203 There is no doubt that certain viruses, the most numerous being the entero- viruses, do survive secondary waste treatment processes including terminal dis- infection. Viruses in sewage effluents from an activated sludge treatment plant in St. Petersburg in 1974, as shown in Table 1, ranged from 0-204 Plaque Form- ing Units (PFU) liter~', with an average of 39, and a median of 13 PFU liter~’. When one considers that the daily effluent output is at least 5 Million Gallons per Day (MGD) the minimal amount of discharged virus based on the median, would be 245,700,000 or 2.5 x 10° PFU day~', whereas, 7.2 x 10° PFU day! would be discharged based on the avg. Recognizing that a single PFU has the capability of initiating infection in man, this represents a very real threat if even 0.1% of this were to enter our potable water sources. TaBLeE |. Virus isolations from 500 ml samples of chlorinated effluent: St. Petersburg spray irri- gation project—1974. Number Range Average Median Month Tested PFU/ Liter PFU/ Liter PFU/ Liter January 6 6-92 45 37 February 3 4-28 13 12 March 1 16 16 16 April 3 34-98 56 36 May 3 52-204 137 154 June 1 32 132 132 July il 0 0 0 August 0 0 0 0 September 2 0-16 8 8 October 4 0-16 7 6 November 1 0 0 0 December 1 i 14 14 TOTAL 26 0-204 39 13 Virus also survives the sludge digestion process. Only a few isolations made from completely digested sludge have been reported in the literature. In the WatTeR NEWSLETTER of November 27, 1974, Ontario’s Health Ministry’s Virus Laboratory reported one virus isolation from 111 samples of digested sludge tested. In attempting to isolate virus from completely digested sludge, we un- successfully tried various concentration methods such as membrane adsorption and polyethylene glycol dehydration. After deciding that virus present must be an integral part of the sludge solids, we devised three different approaches to free the entrapped agents. The first consisted of sonicating (SoniFier, Model W-350, Ultrasonic, Inc.) the digested sludge for 15 min at 100 watts in a rosette cooling cell. The second method provided magnetic stirring in the presence of eluting medium (5% beef extract buffered to pH 9.5 with Tris and NaOH) over- night in the cold room and the third, extraction with Freon. After the individual treatments, samples were reduced to a state of slight wetness by polyethylene glycol hydroextraction at 4°C, reconstituted to 3 ml and centrifuged before inoc- 904 FLORIDA SCIENTIST [Vol. 38 ulation onto Buffalo green monkey kidney cell cultures. Table 2 shows the re- sults. Five samples have been completed and all have yielded agents. It appears that sonication may be the most efficient method, with 4 of 5 specimens being positive; 2 yielding 29 or more PFU. These data would appear to indicate that virus present in sludge is well protected and as such, should survive longer in the terrestrial environment than would virus present in secondary effluents under similar conditions. We have been testing 10 monitoring wells at the sludge spreading site but have found no virus in groundwater to date, nor have we ex- perienced any heavy rainfalls at the site. The project has been in progress for approximately 6 months. TABLE 2. Virus isolations from 500 ml samples of digested sludge: St. Petersburg sod farm proj- ect—1974. Date of Sonication Stirring Freon Specimen No. PFU! No. PFU No. PFU 11-22-74 29 --’ --- 12-02-74 i -- --- 36 ] 0 0 1 0 1 0 1 ‘Plaque forming unit. *Not tested. We have recently completed a study in St. Petersburg (Wellings, et al., 1974) in which monitoring wells at a wastewater land disposal site were tested for virus. Virus was concentrated by the membrane adsorption technique (Wallis, et al., 1969) with the addition of diatomaceous earth (Sigma Chemical Company, St. Louis, Missouri, Celite Grade I) (Hill, et al., 1974). Membranes were homog- enized with mortar and pestle in the presence of alundum and eluting medium (0.15M NaCl in 10% fetal calf serum buffered to pH 9 with Tris). The homog- enate was held on a rotary shaker for an hr before centrifugation at 1,200 X grav- ity for 15 min. Supernate was decanted and concentrated by polyethylene gly- col. After reconstitution to 5 ml, it was centrifuged at 20,000 x gravity for 15 min, treated with 2,000 U of penicillin and 2,000 ug streptomycin ml’ and held at -70°C until assayed for virus in Buffalo green monkey kidney cell cultures. Chlorinated effluents were sprayed on the site through rainbirds. Percola- tion of virus through 5 ft of sandy soil was readily demonstrated shortly after the land spreading began. Positive findings occurred whether the application rates were 2 or 1] in wk~'. However, no virus was found in the 10 ft wells until Sep- tember, 1973, about 1.5 yr after the study was initiated. No effluents had been applied in May and from June on, the application rate was 2 in week~'. Heavy summer rains, 10 in in July, 10 in August and 8 in September, resulted in soil saturation including the 3-5 ft thick organic layer located about 5 ft below ground surface. As these waters began to recede on September 27, difficulty in filtering No. 4, 1975] WELLINGS ET AL.—VIRUS IN SEWAGE EFFLUENT 205 water from the 10 ft well was experienced and coincided with the first virus iso- lation made from a 10 ft well. A second was made on October 3. On October 4, there was a burst of virus (78 PFU) demonstrated. On November 19, a 100 gal sample was negative but on November 26, a coxsackie B4 was isolated from 100 gal. No further isolations have been made from the 10 ft well. The 20 ft well had been tested only once in 1972 and was negative. When positivity was demonstrated in the 10 ft well, the 20 ft well was tested. A 100 gal sample taken on the morning of October 10 yielded 67 PFU and a comparable specimen taken in the afternoon yielded 14 PFU. The following morning a 100 gal sample was negative. All subsequent samples have been negative al- though we have not experienced the same type of soil saturation which occurred at that time. We hypothesized that saturation of the hardpan had resulted in partial solution of this layer thus freeing large quantities of adsorbed virus which passed into the deeper soil strata as groundwater receded. The high water to soil ratio and alkaline pH of the deeper strata would mitigate against readsorption of the virus. A somewhat similar situation was noted in a study we are currently conduct- ing at the Center for Wetlands in Gainesville. Secondary effluents are being discharged into a cypress dome where H. T. Odum of the University of Florida felt that the multiecosystems may provide a better polishing of these waters. Application of effluents was initiated in April, and on May 15 virus was iso- lated from a 50 gal sample drawn from the 10 ft deep well A-16 located approx. VIRAL TEST WELL GROUND WATER WELL 145'peep | EDGE OF WETLAND TYPE VEGETATION Valet ESi Ww BEES EXPERIMENTAL DOME L CENTER FOR WETLANDS UNIVER SITY OF FLA. SEPT 1974 SCAL E; AS SHOWN Fig. 1. Viral test wells in Experimental Dome | at the University of Florida Center for Wetlands. 206 FLORIDA SCIENTIST [Vol. 38 7 m outside the southwestern rim of the dome pond (see Fig. 1). However, an observation tower had been erected in the center of the dome cutting through the clay confining layers. This may have permitted rapid movement of virus- bearing dome waters into deeper strata. Even so, no effluent was applied to the dome from May 19 through July 2 due to heavy rains. On June 14, 10 ft deep wells, A-9 and A-11, both yielded virus isolates, demonstrating virus survival in this cypress dome milieu for at least 28 days. This represents the first demon- stration of relatively long-term survival of virus in soil under natural conditions. It is of interest to note that bacteriological tests of the A-16 well water which yielded virus on May 16 showed 2 total coliform and no fecals per 100 ml. In the other 2 positive well samples bacteriological tests were not done on the same sample from which virus was isolated. However, samples taken from these wells on June 24th showed 33 total coliforms and 13 fecal per 100 ml in well A-9 and 2 total and no fecals per 100 ml in well A-11. From a bacteriological stand- point both A-11 and A-16 would have been considered negative. A second experimental dome is now being tested and no structures which might disturb the natural confining layers will be placed in the dome. All moni- toring wells will be located outside the dome. Data presented here must be con- sidered as minimal findings because the virus concentration techniques avail- able today are anywhere from 10% to possibly 40% efficient. In summary, we have both laboratory and—of more acute concern—field evi- dence that virus does percolate through soils, is adsorbed by the soil, can be de- sorbed, moves with the subsurface waters, and can survive in the soil for at least 28 days. ACKNOWLEDGEMENTS— These studies were supported in part by a grant from the City of St. Petersburg and a Rockefeller Foundation Grant No. RF 74064. James W. Ordway at the Center for Wetlands directed construction of moni- toring wells and provided Fig. 1. His aid is gratefully acknowledged. LITERATURE CITED Drewry, W. A., AND R. Extassen. 1968. Virus movement in groundwater. J. Water Pollut. Contr. Fed. August, 1968:257-271. ELIAssen, R., anp R. H. Cummincs. 1949. Analysis of waterborne disease outbreaks 1935-45. J. Amer. Water Works Assn. 40:509. HaLucren, R. 1942. Epidemic hepatitis in the County of Vasterbotten in northern Sweden. An epidemiological and clinical study. Acta Med. Scand. Suppl. p. 140. Hit, W. F., Jr., E. W. Akin, W. H. Benton, C. J. MAyHEw, AND T. G. METCALF. 1974. Recovery of poliovirus from turbid estuarine water on microporous filters by the use of Celite. Appl. Microbio. 27:506-512. LEFLER, E., AND Y. Korr. 1974. Virus retention and survival in sand. Pp. 84-91. In Ma ina, J. R., Jr., AND B. P. Sacix (eds.) Virus Survival in Water and Wastewater Systems. Proc. Water Res. Symp. No. 7. Mack, W.N., Lu YuE-sHounc, anv D. B. Coonon. 1972. Isolation of poliomyelitis virus from a con- taminated well. Health Services Rpts. 87(3):271-274. Mos ey, J. W. 1959. Waterborne infectious hepatitis. New England J. Med. 261:703-748. Tucker, C. B., W. H. Owen, anv R. P. Farreu. 1954. An outbreak of infectious hepatitis appar- ently transmitted through water. Southern Med. J. 47:732. Wa tis, C., S. Grinstetn, J. L. MELNICK, AND J. E. Fretps. 1969. Concentration of viruses from sewage and excreta on insoluble polyelectrolytes. Appl. Microbio. 18:1007-1014. No. 4, 1975] WELLINGS ET AL.—VIRUS IN SEWAGE EFFLUENT 207 We uincs, F. M., A. L. Lewis, Anp C. W. Mountain. 1974. Virus survival following wastewater spray irrigation of sandy soils. Pp. 253-260. In Maina, J. F., JR., anp B. P. Sacix. Virus Sur- vival in Water and Wastewater Systems. Proc. Water Res. Symp. No. 7. Younc, R. H. F., anp N. C. Burpank, Jr. 1973. Virus removal in Hawaiian soils. J. Amer. Water Works Assn. Sept. 1973:598-604. Florida Sci. 38(4):202-207. 1975. Academy Symposium AN OVERVIEW-WASTEWATER TREATMENT DISPOSAL SYSTEMS UTILIZING LAND APPLICATION RusseE.LL L. WRIGHT Hydrogeologist, Water Programs Office, Technical Support Branch, Region IV, Environmental Protection Agency, Atlanta, Georgia 30309 INCREASED PUBLIC CONCERN about the quality of water that goes into our streams and lakes has forced federal, state, county, and local community officials to seek alternate wastewater disposal methods. Some wags have often used the phrase “the solution for pollution is dilution.” This, however, is far from being the case. Even today, in spite of the economic situation, industries are more than doubling their normal volume of wastewater, and some cities and towns are even tripling their wastewater discharge. It has long been recognized that most lands have the assimilative capacity for handling common organic wastes. The discharge of sewage effluent into streams and lakes adds nitrogen, phosphorus, potassium, calcium, magnesium, sodium, and several other elements that in all probability will create conditions that are detrimental to the aesthetic and recreational values of our waters. For the purpose of establishing eligibility for grant funding under Title IJ, and to insure that all EPA grant-assisted projects comply with the intent of Public Law 92-500, 40 CFR 35,917(d) of EPA’s construction grant regulations requires that all projects funded after June 30, 1974, shall be based upon appli- cation of Best Practicable Waste Treatment Technology (BPWTT) as a mini- mum. In March 1974, EPA published a proposed definition of BPWTT, which requires the evaluation of technologies included under each of the following waste treatment management techniques: 1) Biological or physical chemical treatment and discharge to receiving waters; 2) treatment and reuse; and 3) land application techniques. Best practicable waste treatment technology is the selection of any particu- lar treatment management techniques governed by cost-effectiveness as well as by general environmental consideration to meet water quality standards or minimum effluent limits. Land application systems shall be so designed that the 208 FLORIDA SCIENTIST [Vol. 38 permanent groundwaters (or groundwater which is not removed from the ground by an underdrain system or other mechanical means) which are in the zone of saturation (where the water is not held in the ground by capillary tension) that would result from the application of wastewater will not exceed the bacterio- logical, chemical, or pesticide levels for raw or untreated drinking water sup- ply sources in the EPA manual for evaluating public drinking water supplies. Land application techniques are of two types with respect to discharge. One involves collection of wastewater in underdrain systems; where these systems discharge to navigable waters, they must meet the treatment and discharge cri- teria. The other technique involves the percolation of wastewater through the soil until it becomes part of the permanent aquifer. Land application and land EVAPORATION SPRAY OR oe SURFACE | 1f. =e APPLICATION sien VARIABLE ROOT ZONE = | 1 | eee SUBSOIL_ ————» PERCOLATION (a) IRRIGATION EVAPORATION = 2 ON fees AND VEGETATIVE LITTER —, SHEET FLOW PERCOLAT toy 100-300 ene | (B) OVERLAND FLOW SPRAY APPLICATION SLOPE 2-8% SPREADING BASIN SURFACE APPLICATION INFILTRATION —— or PERCOLATION THROUGH oo ec UNSATURATED ZONE ZONE OF AERATION fy eae AND TREATMENT Bes ae gue Ss NEW WATER TABLE RECHARGE MOUND eters te AI i i Se ae Sas Zi Sa . : oh ee OLD WATER TABLE (c)_ INFILTRATION-PERCOLATION Fig. 1. Three basic approaches to land application of wastewater. No. 4, 1975] WRIGHT—WASTEWATER DISPOSAL SYSTEMS ON LAND 209 utilization are the two major wastewater management techniques that do not result in point source discharges. Groundwater criteria reflect the level of groundwater protection desired. The criteria are geared to making land application technologically and eco- nomically feasible while protecting the groundwater from permanent contam- ination or costly renovation. Pollutants affecting groundwater fall into three categories: 1) chemical pol- lutants such as heavy metals, dissolved salts, and nitrates; 2) organic pollutants such as pesticides and residual organics; and 3) pathogenic pollutants such as bacteria. The technology for removing heavy metals, dissolved salts, and nitrates in a treatment plant to levels that will meet drinking water standards is not prac- ticable for publicly owned plants. The technology exists to remove pesticides and residual organic compounds from groundwater. Activated carbon absorption can be used in a water treatment plant to reduce organic pollutants to levels ac- ceptable for drinking water purposes. However, the cost will be more than double the normal cost of the water treatment in most cases. The criteria for the best practicable system, however, do require reducing chemical and organic pol- lutants to raw or untreated drinking water supply source levels. This require- ment applies to the processing of both effluent and sludge. TABLE 1. Generalized characteristics of land application approaches. TYPE OF APPROACH INFILTRATION FACTOR IRRIGATION OvERLOAD FLOow PERCOLATION Liquid, loading rate 0.5 & 4 in/wk 2 to 5.5 in/wk 0.3 to 1.0 ft/wk Annual application 2 to 8 ft/yr 8 to 24 ft/yr 18 to 500 ft/yr Land required for 1 62 to 560 ac. 46 to 140 ac. 2 to 62 ac. MGD flow + buffer zone + buffer zone + buffer zone Application techniques spray & surface usually spray usually spray Soils moderately per- slowly per- rapidly perme- meable soils meable soils able soils such with good such as clay as sands, loamy productivity loams and sands & sandy when irrigated clay loams Probability of influ- encing ground water quality moderate slight certain Needed depth to groundwater about 5 ft undetermined about 15 ft. Wastewater losses predominantly predomi- percolation to evaporation or nantly sur- groundwater deep percola- face dis- tion charge but some evapo- ration and percolation 210 FLORIDA SCIENTIST [Vol. 38 TABLE 1. (continued) Primary Objectives for Land Application Approaches OBJECTIVE Use as a treatment process with a recovery of treated 50 to 60% Up to 90% water Impractical recovery recovery Use for Treatment Be- yond Secondary For BOD and suspended solids removal 90-99% 90-99% 90-99% For nitrogen removal 85-90% 70-90% 0-80% For phosphorus removal 80-90% 50-60% 75-90% Use to grow crops for sale excellent fair poor Use as direct cycle to the land complete partial complete Use to recharge groundwater 0-30% 0-10% up to 90% Use in cold climates fair* --> excellent *Conflicting data—woods irrigation acceptable, cropland irrigation marginal. *Insufficient data. Irrigation, overland flow, and infiltration percolation, the three basic ap- proaches to land application are diagrammed in fig. 1. The controlling factors in this type of land application are site selection and design, methods of irri- gation, loading rates, management and cropping practices, and the expected treatment or removal of wastewater constituents (Table 1). Factors involved in site selection are: type, drainability, and depth of soil; nature, variation of depth, quality and present and potential use of groundwaters; location, depth and type of underground formation; topography, and consid- eration of public access to the land (Table 2). Climate is as important as the land in the design and operation of irrigation systems. It is not a variable, however, because feasible sites must be within economic transmission distance of the source. In general, soils ranging from clay loams to sandy loams are suitable for irri- gation. Soil depth should be at least 2 ft of homogenous material and preferably 9-6 ft throughout the site. This depth is needed for extensive root development of some plants as well as for wastewater treatment. The minimum depth to groundwater should be 5 ft to insure aerobic condi- tions. If the native groundwater is within 10-20 ft of the surface, control proce- dures such as underdrains or wells may be required. No. 4, 1975] WRIGHT—WASTEWATER DISPOSAL SYSTEMS ON LAND 211 TABLE 2. Practical factors and criteria for irrigation. FACTOR CRITERION Soil type Loamy soils preferably, but most soils from sands to clays are acceptable. Soil drainability Well-drained (more than 2 in/day) soil preferred. Soil depth Uniformly at least 5 to 6 ft throughout site. Depth to Groundwater Minimum 5 ft Groundwater control May be necessary to insure treatment if water table is less than 10 ft from surface. Groundwater movement Velocity and direction must be determined. Slope Up to 15% are acceptable with or without terracing. Underground formations Should be mapped and analyzed with respect to interference with groundwater or percolating water movement. Isolation Moderate isolation from public preferable, the degree depending on wastewater characteristics, method of application and crop. Distance from source of wastewater Economics. The ideal is moderately permeable soil capable of infiltrating approximately 2 in per day or more on an inter- mittent basis. For crop irrigation, slopes are generally limited to about 10% or less, de- pending on the type of farm equipment to be used. Heavily foliated hillsides up to 30% in slope have been spray irrigated successfully. A suitable site for typical secondary effluent wastewater (Table 3) irrigation would preferably be located in an area where contact between the public and the irrigation water and land is limited. However, this is often impossible. The important loading rates (Table 4) are liquid loading in terms of in per wk and nitrogen loading in terms of lbs per acre per yr. Organic loading rates are less important if an intermittent application schedule is followed. Liquid loadings may range from 0.5-4.2 in per wk. Depending on soil, crop, climate, and wastewater characteristics, crop requirements generally range from 0.2-2.0 in per wk, although a specific crop’s water needs will vary throughout the grow- ing season. Typical liquid loadings are from 1.5-4.0 in per wk, although waste- water irrigation rates have ranged up to 7.8 in per wk. A generalized division between irrigation and infiltration-percolation system is 4 in per wk. In almost all cases where land application is being practiced, the nitrogen- loading rates have been calculated because of nitrate buildup in soils, underdrain waters, and groundwater. To minimize such buildup, the weight of total nitrogen applied in a year should not greatly exceed that removed by crop harvest. With loamy soils, the permissible liquid-loading rate will be the controlling factor in most cases; for more porous sandy soils, the nitrogen-loading rate may be the controlling factor. A drying period ranging from several hr each day to several wk is then re- quired to maintain aerobic soil conditions. The length of time depends upon the 212 FLORIDA SCIENTIST [Vol. 38 TaBLE 3. Typical Secondary Effluent Characteristics; organic and inorganic compounds com- mon to municipal wastewaters. I. Oxygen-demanding compounds a. BOD 25 b. COD 70 II. Biostimulants a. Nitrogen Total N20 Organic 2.0(as N) +NH, 9.8 as N -NO, 0.0 as N -NO, 8.2 as N b. Phosphorus Total P 10 Ill. Other organic compounds a. Phenols 0.3 b. Chlorinated and other complex organics-(concentrations vary, total concentration of these refractory organic’s approaches 45 mg/] as indicated by the difference between COD-BOD re- sults above. IV. Inorganic compounds a. Metals 0.1 cadmium 0.1 chromium 0.2 copper 0.1 iron 0.1 lead OW manganese 0.2 mercury 5 ppb. nickel 0.2 zinc 0.2 sodium S.A.R. = 4.6 b. Non-metals boron 0.7 chlorides 100 sulfate 125 V. Other characteristics a. suspended solids 25 b. pH 7.0 ‘As mg/liters unless otherwise stated. crop, the wastewater characteristics, and the length of the application period. A ratio of drying to wetting of about 4:1 should be considered a minimum. Treatment of the wastewater often occurs after passage through the first 2-4 ft of soil. The extent of treatment is generally not monitored; when it is, how- ever, removals are found to be on the order of 99% for BOD, suspended solids, and bacteria. As irrigation soils are loamy with considerable organic matter, the heavy metals, phosphorus, and viruses have been found to be nearly completely removed by absorption. Nitrogen is taken up by plant growth if the crop is har- vested. The removals can be on the order of 90%. SUMMARY—Each potential treatment plant site must be evaluated on a case- by-case basis. The final disposal site will also influence the operating and main- tenance and capital costs, as well as many other parameters that should be con- sidered. A. Wastewater Treatment Considerations. 1. Primary treatment with land application. No. 4, 1975] WRIGHT—WASTEWATER DISPOSAL SYSTEMS ON LAND TaBLeE 4. Typical waste load at design rates; load in pounds per acre. MATERIAL BOD 11.1 330 240 Organic N 0.9 27 18.5 NH,* 4.4 132 91 NO,- 0.0 0 0 NO, 3.8 114 76 Total N 9.1 273 185.5 Phosphorus 4.5 135 92 Phenols 0.1 3 2.8 REFRACTORY Organics 20.0 600 415 Cadmium 0.04 2 0.9 Chromium 0.09 2.7 1.8 Copper 0.04 2 0.9 Iron 0.04 1.2 0.9 Lead 0.04 1.2 0.9 Manganese 0.09 ell 1.8 Nickel 0.09 2.7 1.8 Zinc 0.09 2 1.8 Boron 0.3 9 6.5 Chlorides 45.0 1,350 900 Sulfates 56.0 2,520 1,150 2. Waste stabilization lagoon. 3. Trickling filter with surface water discharge. 4. Trickling filter with land application. 5. Activated sludge with surface water discharge. 6. Activated sludge with land application. 7. Biological-chemical treatment. 8. Activated sludge-coagulation-filtration. 9. Tertiary treatment. 10. Physical-chemical treatment. 11. Extended aeration. B. Sludge Treatment and Disposal Considerations. Fr. SS Se Se ews — Pes Thickening-conditioning-filtration-incineration-landfill. Conditioning-centrifugation-incineration-landfill. Thickening-heat treatment-filtration-incineration-landfill. Thickening-digestion-sod drying-landfill. Thickening-digestion-land spreading. Thickening-digestion-ocean disposal. Thickening-digestion-conditioning-filtration-landfill. Thickening-digestion-conditioning-filtration-ocean dumping. Chemical sludge thickening-filtration-incineration-landfill. Chemical sludge thickening-filtration-recalcination. . Chemical sludge thickening-centrifugation-incineration-landfill. Chemical sludge thickening-centrifugation-recalcination. 213 214 FLORIDA SCIENTIST [Vol. 38 For all of the above sludge, considerations were based on sludge produced from activated plants, followed by coagulation and filtration (wastewater treat- ment consideration #8). Consideration 8 was selected because it generates both biological and chemical sludges. It was also selected on the basis of widespread use of activated sludge systems throughout the United States. No single wastewater treatment consideration or sludge disposal considera- tion is optimal for all situations. Nevertheless, acceptable alternatives exist, each with inherent advantages and disadvantages, which change in relative impor- tance as a function of site-specific variables. Consequently, regulatory policy and guidelines must permit flexibility in the decision making process. All wastewater treatment considerations are capable of meeting existing dis- charge regulations if properly designed and operated. Selection between indi- vidual considerations will depend on prevailing conditions at the proposed site. Land application of effluents can be an economical alternative for achieving high levels of organic and nutrient removal. Additional research is needed, how- ever, before the application of treatment plant effluent can feasibly be applied to any food or feed grain crops. All sludge disposal considerations are acceptable if properly designed and operated. Selection of individual courses of action will depend greatly on the condi- tions prevailing at the proposed site. Land spreading of organic sludges offers the potential for both disposal of waste materials, and resource recovery of nu- trient materials otherwise wasted. Because experience is limited, unanswered questions still exist concerning the public health effects and length of soil ex- haustion cycle associated with this practice. Incineration is one of the best developed methods for disposal of sludges, but it affords little opportunity for the reclamation of resources, and it places heavy energy demands on the community. More work is needed to identify specific stack gas contaminants and establish emission standards for individual toxicants. Additional work is required to detail the secondary effects associated with the various treatment considerations. This will allow for optimization from a system overview. Grant and bonding provisions also discriminate against development of pri- vate utilities for the treatment of municipal wastes. Such utilities could be bene- ficial in sponsoring economical regionalization of facilities and continued inno- vation in waste treatment. BACKGROUND DOCUMENTS CEQ-EPA, Municipal sewage treatment—A Comparison of Alternatives. EPA, 1973. Wastewater Treatment Reuse by Land Application, Vol. I and II. EPA-660/2-73-006 A & B, August 1973. Supt. of Documents. U. S. Govt. Printing Off. Washington, D.C. EPA, 1974. Alternate Waste Management Techniques for Best Practicable Waste Treatment. EPA, March 1974. Off. Water Program Operations. Washington, D.C. EPA, 1974. Evaluation of Land Application Systems. EPA-430/9-74-015, September 1974. EPA, Off Water Program Operations. Washington, D.C. SR 171 Wastewater Management by Disposal on the Land. Florida Sci. 38(4):207-214. 1975. Academy Symposium EFFLUENT IRRIGATION AS A PHYSICOCHEMICAL HYDRODYNAMIC PROBLEM ALLEN R. OVERMAN Agricultural Engineering Department, University of Florida, Gainesville, Florida 32611 Asstract: Irrigation of cropland with municipal effluent is presently being practiced on a lim- ited scale. Studies have shown that a number of physical, chemical, and biological processes occur within the soil-water-plant system. Interactions among these processes are discussed and a mathe- matical framework is described for modeling some of them. THE TITLE chosen for these remarks deserves some elaboration at the outset. “Effluent Irrigation . . .” refers to irrigation of cropland with waste water, par- ticularly municipal sewage effluent. In the United States irrigation is preceded by pretreatment (primary, secondary, or tertiary) and disinfection (chlorination). In the context here “... Physicochemical Hydrodynamic . . .” refers to physical and chemical rate processes that influence transport of a given solute, as dis- cussed by Levich (1962). A survey of effluent irrigation systems has been conducted by Sullivan, Cohn, and Baxter (1973) of the American Public Works Association under contract for the U. S. Environmental Protection Agency. Of the 140,000 acres irrigated at sites included in the survey, about two-thirds were planted to forage crops. Only a small percentage was planted to fruits and vegetables. The largest effluent irri- gation system in the world was found to be in Mexico City with a daily flow of 430 MGD (MGD=nmillion gallons per day) and an area of 115,000 acres. The next largest system was in Melbourne, Australia, with a flow of 96 MGD and an area of 17,000 acres. Application of sewage sludge to land was begun in Hert- fordshire, England, in 1952 onto 6,000 acres to produce grass, grain, and po- tatoes. The largest designed system in the U. S. was that at Muskegon, Michigan, with a flow of 43 MGD onto 6,000 acres. Design factors for effluent irrigation have been discussed by Pound and Crites (1973) in a contract report for the U. S. Environmental Protection Agency. Some characteristics of “typical” secondary effluent have been abstracted from their report and shown in Table 1. Particular attention has been given to fac- tors such as climate, groundwater hydraulics, application rates, vegetation, sys- tem components, and system reliability. Results from 10 yr of field experience at Pennsylvania State University have been reported by Sopper and Kardos (1973). The soil-crop complex was found effective in removing suspended solids, bacteria, and nutrients from the waste- water and provided a percolate suitable for groundwater recharge. Experience with effluent irrigation at Tallahassee has been described by Overman and Smith (1973). Nitrogen recovery for pearl millet was 75% at an 216 FLORIDA SCIENTIST [Vol. 38 TaBLE 1. Characteristics of typical secondary effluent. Component Value Total solids 425 Total suspended solids 25 Total dissolved solids 400 BOD 25 COD 70 Total nitrogen 20 Total phosphorus 10 Chlorides 45 Sodium 50 Potassium 14 Calcium 24 Magnesium hee pH 7.0 'Source: Pound and Crites (1973). application rate of 5 cm per wk. Efficiency of nutrient recovery was observed to decrease with increase of application rate. Dry weight of forage increased with rate, while moisture content also increased. Various summer and winter forage crops have shown good growth response under effluent irrigation. RaTE Processes—Processes such as convection, diffusion, adsorption, ion exchange, and chemical reactions influence solute movement in soil. The soil tends to filter out suspended solids (Tchobanoglous and Eliassen, 1970), bacteria (Dazzo, Smith and Hubbell, 1973), and virus (Drewry and Eliassen, 1968). Con- vection (water flow) tends to transport suspended solids and dissolved solutes through the soil profile. Concentration gradients cause net movement of solutes within the soil solution due to the kinetic nature of liquids. Adsorption and ion exchange reflect movement of solutes between solution and solid surfaces within the soil. Factors such as ionic strength, redox potential, bacterial activity, and soil type strongly influence these processes. Furthermore, some of the processes may be coupled, i.e., convection and diffusion (dispersion), convection and chem- ical reactions, and chemical transformation and biological activity. The theory of physicochemical hydrodynamics deals with the mathematics of such coupled processes. Water Movement. The flow of water in soil may be described by (Kirkham and Powers, 1972) v > ( KvH )-60/ét = 0 (1) where t is time, 6 volumetric water content, H hydraulic head, K hydraulic con- ductivity, v the vector gradient operator, and v- the vector divergence opera- tor. It should be noted that 6, H, and K are point functions that may change values in space and time. For unsaturated flow we write K=K(h), where h is pressure head (negative for unsaturated conditions). Since H=h+Z (2) No. 4, 1975] OVERMAN—EFFLUENT IRRIGATION HYDRODYNAMICS 217 where Z is vertical distance, Equation (1) becomes nonlinear for unsaturated flow. Solutions to these boundary-value problems are handled either through simplifying assumptions or by numerical methods (Kirkham and Powers, 1972). For saturated flow in a homogeneous soil, the one-dimensional flow equation becomes d@?H/dZ* = 0 (3) and the rate of flow is described by Darcy’s equation V = -KdH/dZ (4) where V is the flux, or volumetric flow rate per unit area. Saturated hydraulic conductivity values of sands are typically in the range 10° *-10-* cm/sec. For a unit gradient (-dH/dZ = 1), these values lead to a flux range of 9-900 cm/day. It becomes apparent that convective transport of solutes may be fairly rapid in saturated sandy soil if proper conditions prevail. Sandy soils are very sensitive to capillary tension. Overman and West (1972) have shown that for Lakeland fine sand the hydraulic conductivity dropped from 4-10-* cm/sec at 34% water content (saturation) to 4°10-° at 13% water content (55 cm water tension). It is apparent that sandy soil becomes very restrictive to water movement as it drains and water tension rises. For conductivity of 10° cm/sec and unit gradient, 33 hr would be required for water to move 1 cm in the soil. We see that flow rates in the sandy soils of Florida may vary over a wide range. Consequently, convective transport of solutes may vary over a wide range, also. Phosphorus Transport. In recent times removal of phosphorus from waste- water has received increased attention because of its role in cultural eutrophi- cation of lakes and streams. With effluent irrigation phosphorus must be re- duced from about 10 mg/1 (Table 1) to some prescribed level by plants, soil, or within the aquifer. Many Florida soils have the capacity to fix phosphorus in as- sociation with iron, aluminum, and calcium. Studies are presently underway in our own and other laboratories to model its movement in soil. Phosphorus transport in soil is believed to involve the processes of convec- tion, diffusion, adsorption, and chemical reaction. For steady, uniform convec- tion, linear adsorption, and a first-order chemical reaction, we may write for vertical transport D &P/6z’ - V6P/6z-kP-e( 1+R) dP/dt = 0 (5) where P is phosphorus concentration in the soil solution, z the depth below soil surface, t the time, D the dispersion coefficient (> diffusion coefficient), V the Darcy velocity, k the first-order rate constant, ¢ the porosity, and R the distribu- tion coefficient (between solution and adsorbed P). Equation (5) is a homog- eneous, second-order, partial differential equation which may be solved with appropriate boundary and time conditions. Caution must be used in applying Equation (5) to experimental results since the reaction term is not thought to completely reversible and the adsorption term is not believed to be single-valued (exhibiting different values for adsorption and desorption). 918 FLORIDA SCIENTIST [Vol. 38 DEPTH DEPTH te WEAK STRONG FIXATION FIXATION Fig. 1. Phosphorus distribution in soil solution with time. Figure | shows the type of penetration of phosphorus into soil expected with time for soils with weak and with strong fixation capacities. As time advances 0 — t, — t, > ... phosphorus distribution in soil solution shows down- ward movement. When the irrigation schedule stops, solution concentration at any depth will decrease toward zero with time. Some coupling of processes occurs in that D=D(V) and k=k(V), both tending to increase as V is increased. Cho, Strong, and Racz (1970) have applied the theory to movement of P-31 and P-32 in laboratory columns. Nitrogen Transport. Because of possible health effects from nitrate in drink- ing water, more attention is now being directed toward nitrogen removal from wastewater. In effluent irrigation nitrogen may undergo several transformations in the soil. Under aerobic conditions ammonia will be converted to nitrite by certain bacteria and then converted to nitrate by other bacteria. Under proper conditions nitrate may be converted to nitrogen gas by bacteria (denitrification). Transport of nitrogen in soil involves the processes of convection, diffusion, adsorption, and chemical reaction. The sequence of nitrogen transformations may be written as k, k, k, N, — N, — N, ~ WN, ( NH?) ( NO; ) ( NO; ) ( Nz ) (6) where k,, k,, and k, are taken as first - order rate constants. The chemical reac- tion equations for net gain of each species in solution are dN,/dt = -K,N (7) dN,/dt = k,N, -k,N, (8) dN,/dt = k,N, - k,N, (9) No. 4, 1975] OVERMAN—EFFLUENT IRRIGATION HYDRODYNAMICS 219 N,mg/I fe) 5 fe) 15 20 N 400 No E = 300 A = == 5 & ra _200 — | Se W = > 100 a a fe) ) 20 40 60 80 100 AGE , DAYS Fig. 2. (left) Nitrogen distribution in soil solution at steady-state. Fig. 3. (right) Growth response of irrigated corn (Bar-Yosef and Kafkafi, 1972). The corresponding transport equations for vertical flow with constant and uni- form convection are D 8&N,/8z? - V8N,/6z-k,N, -( 1+R )edN,/dt = 0 (10) D &N,/8z?- VSN,/dz + k,N, -k,N, - e6N,/6t = 0 (11) D &N,/6z? - VON,/dz + kN, -k,N, - eN,/dt = 0 (12) where ammonia, nitrite, and nitrate are assumed to have equal dispersion co- efficients. Equation (10) contains a distribution coefficient since NHf may un- dergo ion exchange in soils, while NO; and NO; do not. Equations (10)—(12) may be solved simultaneously with appropriate boundary and time conditions. Figure 2 shows steady-state distributions of N,, N., and N, that would be expected from continuous irrigation with effluent containing N7=20 mg/1, N=0, and N’=0. In this case N, decays exponentially, N, rises to a peak and then declines to zero, while N, rises to a peak and declines. If no denitrification occurs, then k, =0 and N, rises to 20 mg/1. In general for complete nitrification without denitrification N, (final)=N{7+N?+N$. As with phosphorus, some coupling of processes occur since D = D(V) and k=k(V). Cho (1971) has applied the theory to nitrogen transport in laboratory columns. Crop Growth. Many studies have been conducted to determine the response of crops to fertilization and irrigation. Bar-Yosef and Kafkafi (1972) measured the growth response and nutrient composition of irrigated corn under nitrogen and phosphorus fertilization. Their results are shown in Figs. 3—9 for nitrogen and phosphorus rates of 400 and 80 kg/ha, respectively. The sigmoidal growth curve (Fig. 3) is typical of that found by other investigators. Corn showed a lag period of about 20 days before appreciable growth appeared. At an age of 90 days maximum yield had been reached, the age at which it would have been harvested for silage or green chop. Corresponding to the increase in dry matter 220 FLORIDA SCIENTIST [Vol. 38 4 4 53 3 = =] a 2 ~N # S 2 iS 2 a [e) a oO | O oO 0 20 40 60 80 100 0 20 40 60 80 100 AGE, DAYS AGE , DAYS Fig. 4. (left) Nitrogen content of irrigated corn with age (Bar-Yosef and Kafkafi, 1972). Fig. 5. (right) Nitrogen uptake of irrigated corn with age (Bar-Yosef and Kafkafi, 1972). was a rapid decrease of nitrogen content (Fig. 4), from 4.5%N at 10 days age to 1.2%N at 90 days age. Crop nitrogen (Fig. 5) rose to a maximum at about 65 days and then slowly declined. Phosphorus content of the corn (Fig. 6) rose from 0.2% at 10 days, to a maximum of 0.4% at 25 days, then rapidly declined to 0.18% at 90 days. Crop phosphorus (Fig. 7) rose rapidly between 20 and 90 days toward a maximum of approximately 0.55%. Nitrogen content of the corn (Fig. 8) in- creased with applied nitrogen toward a maximum of approximately 1.3%. Simi- larly, phosphorus content (Fig. 9) increased with applied phosphorus, toward a maximum of approximately 0.2%. Irrigation has been found to influence moisture content of forage crops. Over- man and Smith (1973) observed a decrease in dry matter content (Fig. 10) for pearl millet with increased irrigation rates, approaching a minimum of 14%. A theory of plant growth processes has not been developed, as has been done for water and solute transport in soil. Experience has shown that growth re- 05 04 0.8 03 Oe Cc o a. a ~N 2 e o 0.2 04 a (o) fs or 02 0 0 0 20 40 60 80 100 0 20 40 60 80 100 AGE, DAYS AGE, DAYS Fig. 6. (left) Phosphorus content of irrigated corn with age (Bar-Yosef and Kafkafi, 1972). Fig. 7. (right) Phosphorus uptake of irrigated corn with age (Bar-Yosef and Kafkafi, 1972). No. 4, 1975] OVERMAN—EFFLUENT IRRIGATION HYDRODYNAMICS 221 2 2a 2 | re) 30 0 200 400 APPLIED N, kg/ha aw F 20 re = > & r) Ps 0 %% 100 200 0 5 10 15 20 APPLIED P, kg/ha IRRIGATION RATE, cm/week Fig. 8. (upper left) Nitrogen content of irrigated corn with applied nitrogen (Bar-Yosef and Kafkafi, 1972). Fig. 9. (lower left) Phosphorus content of irrigated corn with applied phosphorus (Bar- Yosef and Kafkafi, 1972). Fig. 10. (right) Dry matter of pear! millet with irrigation rate (Overman and Smith, 1973). sponse, nutrient content, and dry matter content are all related to climate, crop, soil, and cultural practices. A rate model is very much needed that would in- corporate these parameters and would describe the dynamic link between plant growth and soil factors through the root system. ConcLusion—Effluent irrigation of cropland involves movement of water and solutes through the soil. Mathematical description of water movement re- quires information on the hydraulic conductivity. In sandy soils this parameter is very sensitive to water content. Mathematical description of solute transport is possible through the theory of physicochemical hydrodynamics and involves convection, diffusion, adsorption, ion exchange, and chemical reactions. Crop response involves dry matter accumulation, moisture content, nutrient uptake, and chemical composition. At present a descriptive theory is not avail- able for plant production. Field experience remains the primary guide in this area. LITERATURE CITED Bar-Yoser, B., anp U. Karxari. 1972. Rates of growth and nutrient uptake of irrigated corn as af- fected by N and P fertilization. Soil Sci. Soc. Amer. Proc. 36:931-936. Cuo, C. M. 1971. Convective transport of ammonium with nitrification in soil. Canadian J. Soil Sci. 51:339-350. J. Stronc, anv C. J. Racz. 1970. Convective transport of orthophosphate (P-31 and P-32) in several manitoba soils. Canadian J. Soil Sci. 50:303-315. Dazzo, F., P. Smitu, anp D. HusBE.v. 1973. Vertical dispersal of fecal coliforms in Scranton Fine Sand. Proc. Soil & Crop Sci. Soc. Florida 32:99-102. Drewry, W. A., anv R. ELiassEn. 1968. Virus movement in groundwater. J. Water Pollut. Contr. Fed. 40:R257-271. 222 FLORIDA SCIENTIST [Vol. 38 KirkHaM, D., anp W. L. Powers. 1972. Advanced Soil Physics. John Wiley & Sons, Inc. New York. Levicu, V. 1962. Physicochemical Hydrodynamics. Prentice-Hall, Inc. Englewood Cliffs, New ersey. pee A. R., anp T. P. Smiru. 1973. Effluent irrigation at Tallahassee. In Proceedings of Work- shop on Landspreading Municipal Effluent and Sludge in Florida. Univ. Florida. Gainesville. , AND H. M. West. 1972. Measurement of unsaturated hydraulic conductivity by the constant outflow method. Trans. Amer. Soc. Agr. Eng. 15:110-111. Pounp, C. E., anp R. W. Cries. 1973. Wastewater Treatment and Reuse by Land Application. Off. Res. Develop. EPA. Washington, D.C. Soprer, W. E., anp L. T. Karpos. 1973. Recycling Treated Municipal Wastewater and Sludge Through Forest and Cropland. Pennsylvania State Univ. Press. University Park. SULLIVAN, R. H., M. M. Coun, anv S. S. Baxter. 1973. Survey of Facilities Using Land Applica- tion of Wastewater. Off. Water Programs Operations. EPA. Washington, D.C. TCHOBANOGLOUS, G., AND R. ExrassEn. 1970. Filtration of treated sewage effluent. J. Sanitary Eng. Div., Amer. Soc. Civil Eng. 96:243-265. Florida Sci. 38(4):215-222. 1975. Academy Symposium LAND-SPREADING OF SECONDARY EFFLUENTS G. J. THABARAJ Environmental Administrator, State of Florida, Department of Pollution Control, Tallahassee, Florida 32301 SECTION 201 of the Federal Water Pollution Control Act Amendments of 1972 (Public Law 92-500) requires that, “waste treatment management plans and practices shall provide for the application of the best practicable waste treatment technology before any discharge into receiving waters, including re- claiming and recycling of water, and confined disposal of pollutants so they will not migrate to cause water or other environmental pollution and shall provide for consideration of advanced waste treatment techniques.” In accordance with this mandate, the United States Environmental. Protec- tion Agency has designated land application of wastewater as a viable alterna- tive to the traditional treatment-discharge system. Any project subject to federal funding is required to evaluate all feasible alternative waste management sys- tems including land disposal on a cost-benefit basis and to choose the most cost- effective alternative, provided that it also satisfies environmental and other cri- teria. In addition to these federally mandated requirements, the State of Florida has stringent regulations applicable to waste discharges to certain bodies of water in Florida. For example, the Wilson-Grizzle Amendments to Chapter 403 Flor- ida Statutes require advanced waste treatment of sewage before discharge to the coastal waters in the Tampa and lower west coast areas in Florida. No. 4, 1975] THABARAJ—LAND-SPREADING SECONDARY EFFLUENTS 223 Several local pollution control agencies in Florida have also promulgated ordinances requiring advanced waste treatment of wastewaters prior to dis- charge into the bodies of water under their jurisdictions. Since advanced waste treatment systems are complex and expensive, most treatment plants, especially the smaller ones, have elected to go to land dis- posal. Furthermore, in many instances, land disposal of secondary effluents has been found to be more cost-effective than complying with requirements for dis- charge to surface waters. Also, land disposal is becoming an attractive alterna- tive due to its simplicity, reliability and low-energy requirements contrasted with the complex technology and high energy requirements of advanced waste treatment. Land disposal of treated wastewaters has much public appeal these days since it implies “recycling” where the “pollutants” become nutrients for plant growth on land instead of causing nuisance plant growth in receiving waters. The Department of Pollution Control does not endorse the view that land disposal of wastewaters is the panacea for our waste management and water quality problems. Instead, it requires that each waste management alternative be evaluated on the basis of site-specific constraints such as water quality, other environmental impacts and cost-effectiveness. OBJECTIVES AND BENEFITS OF LAND Disposat—The basic objective of any land disposal system should be to produce a renovated effluent that will not degrade the quality of the native groundwaters beyond the water quality limits set forth for drinking water. Exemptions to this policy may apply when the quality of the native groundwaters are not compatible with their prospective use as drinking water. Another major consideration is that the quality of the renovated effluent that moves laterally and discharges to a body of surface water should meet such standards and limitations that are applicable to direct dis- charges to it. The benefits that accrue from the land disposal alternative include preven- tion of degradation of surface waters, water conservation, reclamation of waste lands that are otherwise not arable, prevention of salt water intrusion, preser- vation and enlargement of greenery and open space and economic return from use of water and nutrients to produce marketable crops. In other words, dis- posal of treated effluents on land involves “reuse” that turns the “wastes” toward economic and environmental benefits. PRE-TREATMENT REQUIREMENTS AND ALLOWABLE LoaApinGc Rates—Under Florida's existing statutes and regulations, the minimum treatment for all do- mestic wastewaters is secondary treatment with 90% removal efficiency. Ac- cordingly, all domestic wastewaters should be treated to remove 90% 5-day BOD and suspended solids before disposal by land spreading. Experience to date indicates that, for low-rate land spreading (generally less than 2 to 3 in per wk), secondary treatment, disinfection, storage, good crop management practices and a large buffer area will provide adequate safeguards against risks of ground- water contamination and public health hazards. The critical consideration in applying secondary effluents on land is the ex- 224 FLORIDA SCIENTIST [Vol. 38 tent of removal of applied nitrogen through direct uptake by the vegetation and any incidental losses by denitrification in the soil. Experience at Tallahassee, Florida, indicates that about 650 lb of nitrogen per acre per yr can be removed with a crop rotation of coastal bermuda grass and rye or rye grass. Assuming that a typical secondary effluent contains 25 ppm of total nitrogen and that if the rate of application is 3 in per week with a total loading of 900 lb. per acre per yr, the recovery of nitrogen will amount to about 70%, with about 7.5 ppm in the efflu- ent leaving the root system. It should be borne in mind that the condition and suitability of the soil is of paramount importance in obtaining the maximum recovery of nitrogen through the crop system. The soils best suited for land spreading are those with moder- ate to good drainability and having no less than 5 ft to groundwater and with underground formations not interfering with the movement of percolating water or groundwater. Also, geological discontinuities that may cause short circuiting of applied water to the groundwater should be absent throughout the disposal site. It is, therefore, the policy of this Department to allow up to 3 in of hydraulic application of secondary effluent on suitable soils under good irrigation and crop management practices. If, however, the type of soil or the sub soil condition does not allow sustained application of 3 in per wk of secondary effluent to get maxi- mum renovation efficiency, the rate of application should be lowered in order to be compatible with the site-specific conditions. Artificial sub-surface drainage may be necessary to alleviate the problems related to poor sub-soil drainage or high groundwater elevation. On the other hand, if the availability of land is the limiting consideration, the Department may allow higher hydraulic loading rates provided additional treatment like terminal filtration of the effluents followed by break point chlori- nation is given before land application. This additional treatment will also apply when the disposal site is in close proximity to present or potential residential areas. When the expected renovative capacity of the proposed irrigation system with respect to nitrogen is low, it will then be necessary to accomplish the re- quired degree of nitrogen removal during pre-treatment before land application. However, when it is desired to maximize the usefulness of the hydraulic con- ductivity of the soils, it may even be necessary to provide advanced wastewater treatment prior to use of the limited amound of land as a medium for recharge of the effluents to shallow groundwater through rapid infiltration and percola- tion. It is our belief that pre-treatment standards and requirements should be flex- ible so that the best design for each specific problem or location can be devel- oped by the design engineer. SITE SELECTION AND SPRAY IRRIGATION DeEsicN—The factors to be consid- ered during selection of the land disposal site include availability of land to sat- No. 4, 1975} THABARAJ—LAND-SPREADING SECONDARY EFFLUENTS 225 isfy present and future needs of the irrigation project and compatibility with land-use plans and areawide wastewater management plans. Distance from surface waters and water supply wells should be reviewed from the standpoint of overall hydrology of the system, present water quality constraints and potential impacts of the irrigation system. Also, flood-prone areas should be selected only if protective measures are incorporated in the design. The buffer zone between the irrigation site and adjacent property should be planted with trees and/or deep rooted vegetation. A minimum distance of 150 ft shall be maintained between the periphery of the spray area and any present or potential residential site. Also, minimum of 200 ft distance shall be main- tained from any water supply well or surface waters. Any surface runoff from the spray area should be contained within the site in stormwater retention ponds and may be discharged if applicable effluent discharge requirements are met. Similarly, any stormwater from outside should be intercepted and diverted be- fore reaching the spray area. As mentioned earlier, a sub-surface drainage system will be required to pre- vent the water table from rising to the soil root zone. This is especially necessary when the soil has limited drainability and/or when the rate of hydraulic applica- tion is such as to prevent the maintenance of aerobic conditions in the soil root zone. The sub-surface drainage, so collected, may be discharged to surface waters if it meets the local criteria established for such discharge. All land irrigation systems shall be provided with holding basin(s) having a hydraulic capacity to store 7 days avg daily flow. All effluents shall be stored in the basin after disinfection and before spray application. In addition to this storage capacity, the basin should be designed to handle any temporary storage of the wastewaters during storm or harvesting conditions. A reserve area of no less than 25% of the actually required spray area shall be set aside to provide for future expansion and operational contingencies. The method of (spray) applica- tion should be such as to minimize the wind drift of water droplets from the sprinkler system. Sprinklers adjacent to the periphery of the spray field should be of “low angle” type operated at pressures low enough to minimize atomiza- tion of the effluent spray. DIsINFECTION CRITERIA AND PuBLic HEALTH CoNSIDERATIONS—The major public health consideration in land spreading of wastewater is the possible trans- mission of potentially pathogenic agents like viruses through groundwater and aerosols. Chlorination of wastewaters is not effective in killing the viruses if pro- longed exposure periods and low turbidity levels are not maintained. It has been shown by several workers that chlorination to a free chlorine residual of 1 mg/1 with a contact time of 30 min is normally adequate to completely re- move or inactivate all viruses in waters or wastewaters having a turbidity below one Jackson Turbidity Unit (JTU) and preferably as near as 0.1 JTU as possible. However, in actual practice, it is difficult, if not impossible, to maintain such 226 FLORIDA SCIENTIST [Vol. 38 low turbidity levels in the effluents from secondary effluents. Normally the tur- bidity level in a secondary effluent will range from 20 to 50 JTU. Multi-media filtration after secondary treatment can reduce the turbidity to less than 5 JTU. With a coagulant aid, the turbidity level can be further reduced to less than 1 JTU after multi-media filtration. Since soil filtration of wastewater during spray irrigation essentially removes all suspended and colloidal materials, and since effective virus kill can be easily obtained with chlorination of the renovated wastewater, it is the opinion of this Department that disinfection, rather sterilization, of wastewater to remove all virus particles before land application is not necessary even though it is a de- sirable objective. If the application rate is low (less than 2 in) and adequate buffer zone (greater than 200 ft) to a potential water supply source is provided, applica- tion of adequately disinfected (chlorinated for 30 min at avg flow to produce 0.5 mg/1 total residual) and stored secondary effluent can produce a renovated water that will meet the drinking water (microbiological) standards after break- point chlorination. If high rates of application are desired and/or large buffer areas cannot be afforded, then it will be necessary to provide for (coagulation), multi-media filtra- tion and breakpoint chlorination to effect maximum inactivation of the viruses before land dispersal. No matter what precautions are taken and how fail safe a sewage disposal system might be, it cannot be expected to produce an effluent free of all known (and unknown?) forms of pathogens. The simplest and most prudent precaution against potential public health hazard is to apply maximum possible (cost- effective) controls in treatment and disinfection of the effluents before land dispersal and provide for maximum isolation from residential, and ground water supply/surface water sources. It goes without saying that all water for human consumption that is pumped from well within underground traveling distance from landspreading sites or other potential sources of contamination should be chlorinated beyond break-point level. MoniToRING REQUIREMENTS—The objective of the monitoring system is to detect primarily any adverse changes in the quality of groundwater moving away from the irrigation site. Secondarily, it is also desirable to monitor the changes in the quality of soil, plants, percolate and runoff during sustained and long-term application of wastewater. It is important to consider groundwater flow condi- tions before designing a monitoring system. The location and depth of the moni- toring well should be such as to intercept and sample the groundwater moving away from the boundary of the irrigation site. Ideally, a cluster of wells should be constructed to sample the groundwater at different depths which will provide for the natural fluctuations in groundwater elevations at a particular site. Any monitoring system should provide for sampling of native groundwater at or near the site that is not affected by the landspreading operation. To design meaningful groundwater monitoring system, a hydrogeologic in- vestigation should be undertaken to determine the best monitoring locations. The important parameters that should be monitored in the groundwater include No. 4, 1975] THABARAJ—LAND-SPREADING SECONDARY EFFLUENTS 227 pH, total dissolved solids, total and nitrate nitrogen, total phosphate, chlorides, and total and fecal coliforms. Also, periodic analysis for arsenic, cadmium, chromium, lead, selenium, and mercury in the groundwater should be performed to detect any adverse impact of the land spreading operation on the quality of the groundwater that serves as a source or potential source of drinking water. The Department requires that base-line information on existing ground- water quality be collected at the proposed site in order to provide a data base for future evaluation of the land spreading operations. RESTRICTIONS ON LANDSPREADING OPERATIONS—At the present time, the De- partment does not allow land irrigation of effluents under the following circum- stances: (1) Irrigation of food crops that may be used in its raw or natural state with- out physical or chemical processing sufficient to destroy all pathogenic or- ganisms. (2) School grounds, playgrounds, lawns, parks and other areas where chil- dren may congregate. (3) The nature of soil and groundwater conditions are such that, in the opinion of the Department, landspreading operation would cause water quality degradation in an aquifer that presently serves as the principal source of drinking water. Areas which have public access shall be irrigated only at night. The land spreading area shall be protected to keep livestock and trespassers out. Warning signs shall also be posted. SUMMARY—It may be said that the Department considers landspreading of secondary effluents as a viable alternative to discharge to surface waters. It should be understood, however, that land disposal is not the panacea for our waste management problems. There are several constraints that restrict adop- tion of this method to a particular site. The important considerations are its po- tential impact on the quality of usable groundwater in terms of nitrogen, total dissolved solids, heavy metals and pathogens and the cost-effectiveness of this alternative as contrasted with other methods of treatment and discharge. Before choosing land spreading as the preferred alternative, we have to as- sure ourselves that all potential hazards are eliminated and/or only minimum acceptable risks are involved in comparison with other alternative treatment/ disposal techniques. Florida Sci. 38(4):222-227. 1975. Annual Address REPORT TO THE ACADEMY’ PETER P. BALJET, Executive Director Florida Department of Pollution Control, 2562 Executive Center Circle E, Montgomery Building, Tallahassee, Florida 32301 Ir is a very great pleasure for me to meet with the Academy tonight. Now, more than ever, the efforts and input of top-flight scientists are needed as we make regulatory decisions affecting our environment. These decisions cannot be made in a vacuum. No single group or technical discipline has all the answers to problems involving technology, politics, and eco- nomics. But when views of diverse groups are brought together and put into our action plan, I see more hope than ever today to blend science, economics and pol- itics together for effective environmental policies. One of the most pressing, yet difficult, problems we face in Florida, as you all know, is disposing of our human wastes. In this area, as well as others like land- use planning, air quality, and noise control, we must take a broad view of the problem. Our regulatory actions should be attainable in terms of technology, cost, and political decision-making. For a few minutes tonight, I would like to talk about a promising technique for sewage treatment beyond secondary treatment that may meet some or all of these requirements—land disposal of secondary effluent. To put the problem in some perspective, we know we have over 3000 sewage treatment plants in Florida. Our staff estimates that just to achieve secondary treatment by 1990 will cost some $7 billion—a whopping figure in anybody's book. If we assume advanced treatment costs about twice as much as secondary, we are getting into some almost unmanageable figures. We also know we are facing water shortages that are going to force us to stop using, and in many cases, losing huge quantities of fresh water in disposing of our wastes. Finally, we are dealing with a finite quantity of available land in Florida for our various uses, including waste disposal. With these things in mind, let me just give you generally a picture of how we and the federal authorities view land spreading from the regulatory standpoint as a method of advanced treatment and consequent nutrient removal. I know that you will be talking much more specifically in your symposium with Dr. Jay Thabaraj of our staff who is very heavily involved in state activities in this area. Both the state and the federal water pollution laws cause us to examine very closely the land-spreading alternative for nutrient removal and water reuse when we consider approval of treatment facilities. 'Eprtror’s Note: On the occasion of our annual banquet held March 21, 1975, at Florida Southern College, Peter Baljet addressed those attending with an off-the-cuff presentation (with audience permission) of the increasing need for scientists to become involved in the process a political decision-making. The question and answer period following his remarks was enlightening and pointed up the need for greater service to the state by the Academy and its members. This statement is the text of the formal speech brought to the meeting by our speaker who graciously agreed to allow us to share it with all our members by publication. No. 4, 1975] BALJET—REPORT TO THE ACADEMY 229 Indeed, the Federal Water Pollution Control Act, as amended (section 201, Public Law 92-500) requires that “waste treatment management plans and prac- tices shall provide for the application of the best practicable waste treatment technology before any discharge into receiving waters, including reclaiming and recycling of water, and confined disposal of pollutants so they will not migrate to cause water or other environmental pollution and shall provide for consideration of advanced waste treatment techniques.”’ This very forceful mandate has led EPA to designate land application of wastewater as a viable alternative to traditional treatment-discharge systems. Any project which obtains funding through the federal grant program is required to evaluate all feasible alternative waste management systems, including land disposal, on a cost-benefit basis. After this evaluation, the most cost-effective alternative must be chosen, provided that it also satisfies environmental and other criteria. In other words, land treatment must be considered in the basic selection of method for waste treatment. I might mention parenthetically, however, that the Environmental Protec- tion Agency has been cautious, and rightfully so, when considering the land- spreading method for federally-funded projects. General parameters EPA holds to include holding ponds to contain 5-7 days of the plant’s output in case of heavy rains; hydraulic application rates of 2-4 inches per week, depending on soil con- ditions; application rates of 500 pounds per acre per year of nitrogen; no more than 10 ppm of nitrogen in ground water; and, plenty of monitor wells on the perimeter of the spray irrigation field. The net result is a rule-of-thumb 100-125 acres necessary per million gallons per day (MGD) of the plant’s size. One of the very fine examples of the application of these principles is the new Lynn Haven federally-funded project, with an application rate of 400 pounds of nitrogen per acre per year. In addition to the federal requirements, we have our own stringent regula- tions in Florida for waste discharges. For example, the 1972 “Wilson-Grizzle” amendments to our water pollution law (chapter 403, F.S.) requires advanced waste treatment prior to any discharge to the coastal waters in the Tampa and lower west coast areas in Florida. And, of course, there is the broad catch-all” phrase in the law which allows the Department of Pollution Control to require, administratively, advanced waste treatment “deemed necessary. ” Because advanced waste treatment systems are so very expensive, most treat- ment plants—especially the smaller ones—are employing land disposal to meet the requirements. In many instances land disposal has been found to be more cost-effective than complying with advanced waste treatment regulations in other, more costly ways such as reverse osmosis, ion exchange, or denitrification. Indeed, land disposal can be very attractive cost-wise when compared to other methods. Land disposal is also becoming an attractive alternative due to its sim- plicity, reliability and low-energy requirements as contrasted with the complex technology and high energy requirements of other methods of advanced waste treatment. An obvious disadvantage is the large amount of land required for land disposal. 230 FLORIDA SCIENTIST [Vol. 38 Land disposal has a great deal of public appeal these days since it implies “recycling” —where the pollutants become nutrients for plant growth on land instead of causing eutrophication and nuisance plant growths in receiving waters. It is easy to visualize lush, green parks and golf courses fertilized by ef- fluent from treatment plants—the “ultimate” in recycling in many people’s view. It is especially attractive to people in Florida’s Tampa, Orlando, and Dade County areas where the surface waters are already eutrophic and even ad- vanced treatment of effluents would cause further degradation of the waters. Another popular use of wastewaters is irrigation of crops, if the threat of viruses can be minimized. Moreover, there is increasing use of reclaimed waters for planned ground water recharge. In Florida, where we have the greatest number of first-magnitude springs in the United States (17 with an average flow of 100 second-feet or more), as well as 49 second-magnitude springs (average flow of 10 to 100 second-feet), and with a plentiful average yearly rainfall of 50 inches—it’s somehow hard to visualize that reuse of our sewage effluents could even be necessary. Also there is a tremendous quantity of surface water in Florida during normal years. An average of about 40 billion gallons per day flows, largely unused, into the oceans—but most of the flow is from a few rivers in the northern part of the state. Indeed, either of Florida’s two largest springs has sufficient water to sup- ply a city of over 3 million population, and any of the 20 major springs could serve the drinking water needs of a city of over a half-million. But we all know the so-called “normal years” have become abnormal. There are acute water shortages in some parts of the state causing citizens and public officials serious concern. Yet in some other parts of the state “50-year rainfalls” have become rather common. In any case, we feel technology needs to be pushed to its limit but are hoping there will not be a need to consider direct potable reuse. That is not to say there is not a relationship between other uses and drinking water—keep in mind that all non-potable reuse of water can result in making alternate water sources avail- able for potable use. In the area of drinking water suffice it to say that we hope land-spreading of treated effluent helps us to attain the goal of freeing other water supplies for potable use. We feel Florida’s resources are sufficient so that with good water manage- ment programs we should never be forced to resort to direct reuse of sewage ef- fluent for drinking water. Land disposal for other water consumption purposes may help relieve the pressure on our potable water supplies. Just as the federal authorities are cautious, however, the Department of Pol- lution Control also refrains from strong endorsement of land disposal until more questions are answered. Certainly we cannot see at this time that land disposal will be the “panacea”’ for all our water quality problems in Florida. There are still many aspects of land disposal that have not been thoroughly investigated. For example, the question No. 4, 1975] BALJET—REPORT TO THE ACADEMY 231 of heavy metal uptake by crops has not been satisfactorily answered. Other areas needing more study are the fate of airborne pathogens from irrigation sites, the survival of viruses during land treatment, and possible contamination of ground- water by trace organics that may penetrate the soil. We know that when nutrients are applied to the land, they must be balanced against the nutrient removal capacity of the soil-plant system to minimize groundwater contamination. Heavy applications of sewage waste can result in the movement of nitrogen below the root zone. In spite of these problems and potential problems, we feel that under cer- tain conditions and in certain Florida locations land disposal may be the best, most cost-effective alternative with minimum acceptable risks. Certain bodies of water in Florida, for example, serve as drinking water sup- plies (upper St. Johns, Lake Okeechobee, Caloosahatchee River and Hillsbor- ough River) and should be protected from any direct discharge of sewage efflu- ents. This may be a good example of what IJ have just talked about—relieving the direct pressure on potable water supplies by using land disposal for other pur- poses or reasons. Sewage treatment facilities located in areas upstream of the water supply intakes should be required to dispose of their effluents on land after adequate treatment and disinfection, rather than allowing them to discharge di- rectly to these important drinking water sources or their tributaries upstream. Land disposal offers real promise in helping also to relieve our ever-increasing eutrophication problem. It is fair to say Florida is unique in the whole country in its environmental assets, and we must protect our waters from further over- enrichment that will ruin it for our residents and our economically-important visitors alike. Most of us would agree, I think, that over the long haul secondary treatment, while an obvious improvement over primary or no treatment, will not be ade- quate to allow unlimited discharges of sewage effluents to our inland surface waters and still maintain acceptable water quality. So additional treatment, in- cluding nutrient removal, will eventually be absolutely necessary to prevent eu- trophication. Given the terrific expense of alternative methods of nutrient re- moval, we may very well see more attention given as time passes to adequate pre- treatment and land disposal as a viable alternative for protecting our precious waters. And, of course, the most important questions to be resolved regarding land disposal is, whether in solving one problem we are creating another. With the potential hazards I have mentioned earlier, we may be endangering our usable groundwater by employing this disposal method. And since more than 90 percent of our potable water supply comes from groundwater, it would surely be penny- wise and pound-foolish in the long run to possibly impair the quality of our groundwater in our zeal to protect the quality of surface waters. The most realistic solutions to some of these problems lie in the judicious management of our water resources based on sound decisions. This decision- making process should take into account the most advanced and most practical 232 FLORIDA SCIENTIST [Vol. 38 technology of waste treatment and the cost-benefit aspects of our regulatory ac- tions as they affect our environment. If we do find that land disposal is the most cost-effective and environmentally- sound alternative to direct discharge to streams, then we may very well adopt this course of action subject, of course, to any environmental constraints. We must assure ourselves that the potential hazards are eliminated, or only minimum acceptable risks are involved in the use of land spreading, when it is compared with other available alternative disposal techniques. Just let me emphasize again that we intend to be cautious in our approach to land disposal systems. We do not regard them as the cure-all for our water quality problems. We will, however, encourage them in areas where they present no risk or minimal risks to our environment, because we are seeing some very excellent cost-to-benefit results with them when properly designed and supervised. Above all, we intend to protect and enhance our irreplaceable environmental assets. In that, we cannot let down. Florida Sci. 38(4):228-232. 1975. REVIEWERS FOR 1975 THE suCccEss of a scientific journal depends upon cooperation among many persons giving freely of their time. Authors are recognized for the contributions published bear- ing their name but the unseen hero of the journal is the specialist reviewer. Many authors in our journal and others have been spared embarrassment by sympathetic and painstak- ing reviewers who have fingered lapses in the manuscripts submitted. Recommendations of our reviewers have been cherished by the editor although he has sometimes accepted an author's viewpoint if well-defended and reasonable. It is with sincere pride and warm- est thanks that I acknowledge the invaluable assistance of the following persons in publi- cation of the issues which appeared in 1975.—Editor. DANIEL F. AUSTIN RONALD C. Bairp MONDELL BEACH Joun C. Briccs SAMUEL F’, CLARK GLENN M. COHEN WALTER R. CourTENAY, JR. ERNEST H. Davis THOMAS R. DyE LLEWELLYN M. EHRHART F. E. FREIDL JouN J. Koran, JR. FRANK B. KujAWwA DEAN F. MarTIN WILLIAM M. McCorp Guy C. OMER GEORGE Y. ONADA JouN A. OSBORNE THoMaAs N. Russo FRANKLIN F.. SNELSON JANICE B. SNOOK MICHAEL J. SWEENEY WILLIAM H. Tart WALTER K. TAYLOR Howarp J. TEAS DANIEL B. WarpD LinpAa WarpD-WILLIAMS HEnry O. WHITTIER Rupy J. WopzinskI Academy Medalist CITATION FOR ALEX E. S. GREEN OUTSTANDING SCIENTIST OF FLORIDA Awarded at the Annual Meeting, March 21, 1975 Dr. GREEN’s achievements in advancing the frontiers of science extend all the way from the realm of the particles constituting the atomic nucleus on out through our en- vironment to the sun and the planet Jupiter. Typical of his diversity of talents and produc- tivity throughout his career, were the eight years between his graduation in Physics from the City College of New York and his receipt of the Ph.D. degree in Physics from the University of Cincinnati. In addition to his graduate studies and teaching, he earned a War Department Citation for Outstanding Overseas Service; did important experimental research and development as well as theoretical work on gunnery, fire control, and ballistics; was an instructor in electronics at the California Institute of Technology; achieved a new higher order of precision in the determination of a fundamental constant of modern physics; and published several papers in theoretical physics in the Physical Review. His over two hundred subsequent technical articles and books cover many aspects of theoretical nuclear physics and contribute significantly in such fields as elementary particle theory, field theory, atomic and molecular physics, solar radiation, aurora, the polar cap, instrumentation, laser phenomena, ion propulsion, teaching the teachers, so- ciophysics, radiation biology, ultraviolet radiation and skin cancer, traffic noise, atmos- pherics, aeronomy and pollution. Dr. Green came to Florida State University in 1953 and soon became an advisor to Governor Leroy Collins, who then arranged legislative appropriations for nuclear re- search and development, out of which grew the Van de Graaff program at Florida State University and the reactor program at the University of Florida. After four years away from Florida as manager of the Space Science Laboratory of Convair, Dr. Green came to the University of Florida in 1963, where he is Graduate Re- search Professor of Physics, Electrical Engineering, and Aerospace Engineering, and is Director of the Interdisciplinary Center for Aeronomy and Atmospheric Sciences. Throughout his career, he has been senior investigator on numerous research con- tracts. Also from time to time he has served as lecturer, consultant, and visiting scientist at the laboratories at Oak Ridge, Los Alamos, Aeroneutronic Systems, University of Cali- fornia, Jet Propulsion, Aerospace Corporation, Institute for Defense Analyses, Marshall Space Flight Center, and the Stanford Linear Accelerator. He has participated in nu- merous national and international conferences. The Florida Academy of Sciences takes great pleasure and satisfaction in awarding its 1975 Medal to its own active member, Dr. Alex E. S. Green. Florida Sci. 38(4):233. 1975. Physical Sciences FORMULATION OF THE ENERGY EQUATION IN FLUID DYNAMICS PIETER S. DUBBELDAY Department of Oceanography and Ocean Engineering, Florida Institute of Technology, Melbourne, Florida 32901 ForMUuLATIONS for the energy equation exist in variety in fundamental and applied texts and monographs on fluid dynamics. It is often difficult to establish the set of conditions leading to a given formulation. More deleterious is the fact that in some cases an energy equation as point of departure does not have the generality implied by the accompanying text. In two instances (Chandrasekhar, 1961; Newman and Pierson, 1966) the term (a T/ky ) ¥°V in formula (7) is replaced by pv¥v (for the symbols used see the list at the end of this note). For an incompressible fluid this term is zero, admittedly, while for an ideal gas one has aT/k_ =p, and the difference disappears. It would appear, though, to be a didactic drawback to start from an inexact formula, even though the final approximation is unaffected. Moreover, it is quite possible to imagine situations where neither the incompressible fluid nor the ideal gas would be a satisfactory approximation to reality. In this note a hierarchy of formula- tions is presented for reference, from the general to some restricted cases. A few directions are given to guide in the derivations. The point of departure is the energy equation for the flow of a simple fluid system. (For a derivation from first principles see e.g. Aris, 1962, p. 121) p ( du/dt ) = -¥°G+T:( 77 ) (1) in dyadic notation, or in tensor notation. For a Stokesian fluid this reduces to p ( du/dt ) = -¥°-q-pvv + Y (2) where Y is the viscous dissipation function. For a linear Stokesian (Newtonian) fluid, one finds Y = (A + 2p) (¥V) - 4u ® (3) No. 4, 1975] DUBBELDAY—ENERGY EQUATION IN FLUID DYNAMICS 235 Inserting the relationship between entropy and energy, and enthalpy and energy, into (2) one finds the expressions for the time rate of change of these func- tions as o T (ds/dt ) =-¥q + Y, | (4) and p ( dh/dt ) =-%G + dp/dt + Y (5) Often one utilizes the corresponding equations in terms of the temperature as the main variable (“heat conduction equation’). The transition takes place through standard manipulation (see e.g. Callen, 1960, Chapter 7). It is sketched here, since this appears to be the source of the discrepancies in references (Chandrasekhar, 1961; Newman and Pierson, 1966). For enthalpy, dh =c, dt + ( dh/dp ), dp. Since ( dh/dp )y = ( 1/p )( 1-aT ), we find by inserting into (5), if one also assumes Fourier’s law for heat flow, q = -kvT, Geet /dti je — v-( kvl ) + al ( dp/dt_) + Y (6) A similar expression follows from (2) by noticing that ( du/dv )p = -p + aT/ky, namely pee dil/dt yi ve kvl (alk, ) vv + Y (7) Since for an ideal gas aT = 1, and x; = 1/p, we have the corresponding ex- pressions for that special case. Ideal gas pe.dt/dt = v-( kvl) +-dp/dt + .Y (8) and p- esa l/ dat ¥-(kVT) - pwev + Y. (9) Notice that in the above derivations it was not assumed that c,, c,, k are inde- pendent of position. 236 FLORIDA SCIENTIST [Vol. 38 List of Symbols a = ( l/v )( 6v/6T ),, coefficient of thermal expansion Cc = ( dh/6T),, specific heat at constant pressure (per unit mass) C, = (du/6T),, specific heat at constant volume (per unit mass) (d/dt) = ( 6/ét + v, 6/6 x + v,6/dy + v,6/6z ), total time derivative ei; = (1/2( dv,/dx; + dv,/6dx, ), rate of strain tensor uy , sum of cofactors of diagonal terms in e; ; h , specific enthalpy (unit mass) k , thermal conductivity Kp = -( l/v )( év/ép ),, isothermal compressibility r , viscosity coefficient in T;,= ( -p + AV )6,; + 2ye,; UL , dynamic viscosity p , thermodynamic pressure q , heat flux vector p , density S , specific entropy (unit mass) T , temperature Ts T,, , stress tensor t , time yi , viscous dissipation function u , specific internal energy (unit mass) Vv , velocity vector | Vv , specific volume LITERATURE CITED Aris, R. 1962. Vectors, Tensors, and the Basic Equations of Fluid Mechanics. Chapter 6. Prentice Hall. New Jersey. CALLEN, H. B. 1960. Thermodynamics. Chapter 7. Wiley. New York. CHANDRASEKHAR, S. 1961. Hydrodynamic and Hydromagnetic Stability. Oxford University Press, New Jersey. p. 16. 652pp. NEuMANN, G., AND W. J. Pierson, Jr. 1966. Principles of Physical Oceanography. 2nd & 3rd Print- ing, p. 124. Prentice Hall. Englewood Cliffs, New Jersey. Florida Sci. 38(4):234-236. 1975. Erratum: 1971 Photoelectric Observations of Beta Lyrae [Florida Scientist 37:100 (1974)] The authors and the institutions with which they are associated were incorrectly listed in this paper. Correct addresses are given here: R. M. Williamon, T. H. Morgen and D. H. Martins, Rosemary Hill Observatory, Department of Physics and Astronomy, University of Florida, Gainesville, Florida 32611; T. F. Collins, Department of Physics, Clemson University, Clemson, South Carolina 29631; H. R. Miller, Department of Physics, Georgia State University, Atlanta, Georgia 30303. Florida Scientist QUARTERLY JOURNAL of the FLORIDA ACADEMY OF SCIENCES VOLUME 38 Editor Harvey A. MILLER Published by the FLorRIDA ACADEMY OF SCIENCES, INC. Orlando, Florida 1975 The Florida Scientist continues the series formerly issued as the Quarterly Journal of the Florida Academy of Sciences. The An- nual Program Issue is published independently of the journal and is issued as a separately paged Supplement. Copyright © by the FLoripa Acapemy oF SciEncEs, Inc. 1975 CONTENTS OF VOLUME 38 NuMBER | Bird flowers in the eastern United States Daniel F. Austin Distribution of the river birch, Betula nigra, in the United States James L. Koevenig Feeding habits of the white catfish from a Georgia estuary Richard W. Heard Plagusia depressa from the northeastern Gulf of Mexico Keitz Haburay A new subspecies of Anolis baleatus Cope (Sauria: Iguanidae) from the Republica Dominicana Albert Schwartz An unusual habitat for the fish Rivulus marmoratus Fredrick W. Brockmann Coloration changes in sub-adult largemouth bass exposed to light and dark background E. J. Moyer and R. L. Wilbur Biology texts utilized in Florida secondary schools Barbara Ann Whittier Some English comments on the Treaty of Versailles and the United States Senate George Osborn Treasurer's note NUMBER 2 Distribution of the boring isopod Sphaeroma terebrans in Florida David O. Conover and George K. Reid The status of prehistoric sites in Pinellas County, Florida J. Raymond Williams Soil algae from North Central Florida J. R. Norton and J. S. Davis Firing of soft phosphate yields a bloated product Frank N. Blanchard A preliminary list of Fijian mosses Henry O. Whittier Carotenoids in color change of Pomacentrus variabilis Hal A. Beecher Life history patterns in the coastal shiner, Notropis petersoni, Fowler Bruce C. Cowell and Clippert H. Resico, Jr. Occurrence and possible establishment of Hoplias malabaricus (Characoidei; Erythrinidae) in Florida Dannie A. Hensley and Derril P. Moody NUMBER 3 Temporal patterns of resource allocation and life history phenomena Mercedes S. Foster The southern distribution of the many-lined salamander, Stereochilus marginatus Stephen P. Christman and Howard L. Kochman First records of two percid fishes in Florida freshwaters Ralph W. Yerger and Hal A. Beecher The Florida spiny lobster fishery—A white paper Gary L. Beardsley, T. J. Costello, Gary E. Davis, Albert C. Jones and David C. Simmons Benthic algae of the Anclote Estuary I. Epiphytes of seagrass leaves David Ballantine and Harold J. Humm Elemental analysis of selected Merritt Island plants David H. Vickers, Roseann S. White and I. Jack Stout Range extensions for, and an abnormality in, Scorpaenid fishes collected off the Carolinas William D. Anderson, Jr., James F. McKinney and William A. Roumillat Notes on the introduced gecko Hemidactylus garnoti in South Florida Robert Voss Key to the mosses of Puerto Rico Harvey A. Miller and Keith W. Russell Invasion of a renovated pond by walking catfish, Clarius batrachus (Linnaeus), and other species Lothian A. Ager NUMBER 4 ACADEMY SYMPOSIUM: Lanpb SPREADING OF SECONDARY EFFLUENT Introduction Rudy J. Wodzinski Chemical, physical and biological composition of “typical” secondary effluents Rudy J. Wodzinski Virus consideration in land disposal of sewage effluents and sludge F. M. Wellings, A. L. Lewis, C. W. Mountain and L. M. Stark An overview—wastewater treatment disposal systems utilizing land application Russell L. Wright Effluent irrigation as a physicochemical hydrodynamic problem Allen R. Overman Land-spreading of secondary effluents G. J. Thabaraj Report to the Academy Peter P. Baljet Reviewers for 1975 Citation for Alex S. Green Formulation of the energy equation in fluid dynamics Pieter S. Dubbelday FLORIDA SCIENTIST 37(3) was mailed on April 4, 1975. FLORIDA SCIENTIST 37(4) was mailed on June 9, 1975. FLORIDA SCIENTIST 38(1) was mailed on June 30, 1975. FLoripA SCIENTIST 38(2) was mailed on October 2, 1975. FLORIDA SCIENTIST 38(3) was mailed on November 14, 1975. 129 140 142 144 150 163 171 174 175 183 193 194 202 207 215 222 228 232 233 234 INSTRUCTIONS TO AUTHORS Rapid, efficient, and economical transmission of knowledge by means of the printed word requires full cooperation between author and editor. Revise copy before submission to insure logical order, conciseness, and clarity. Manuscripts should be typed double-space throughout, on one side of numbered sheets 8% by 11 inch, smooth, bond paper. A Carson Copy will facilitate review by referees. Marcins should be 1% inches all around. Footnotes should be avoided. 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