EH61HEEMKG \ :;-- /; a I B ^AHY OF THE U N IVLRSITY Of ILLI NOIS 62$ IJL65c »o. 33-35 ENGINEERING COW. ROOM ENGIN RAMI Latest Date stamped below * -e , LTott r n d i s Ond 1 Under ' inin9 of b °°«* ^ srrsr- ^ — SEP 16 L161— O-1096 Digitized by the Internet Archive in 2013 http://archive.org/details/fateofsyntheticd33bane CIVIL ENGINEERING STUDIES SANITARY ENGINEERING SERIES NO. 33 FATE OF SYNTHETIC DETERGENTS IN SOIL AND GROUND WATER By SHANKHA K. BANERJI and BEN B. EWING FINAL REPORT SEPTEMBER 1, 1959 THROUGH JANUARY 31, 1965 Supported By DIVISION OF WATER SUPPLY AND POLLUTION CONTROL U. S. PUBLIC HEALTH SERVICE RESEARCH PROJECT WP-00018 DEPARTMENT OF CIVIL ENGINEERING UNIVERSITY OF ILLINOIS URBANA, ILLINOIS NOVEMBER, 1965 Q w M CO CO FATE OF SYNTHETIC DETERGENTS IN SOIL AND GROUND WATER by Shankha K. Banerj i and Ben B. Ewing o CN rH UD CTi rH in H VO O o CO O CM Final Report September 1 , 1959 i— i through January 31, 1965 o t-t bq > <^ UK < O M Supported by Division of Water Supply and Pollution Contro U.S. Public Health Service Research Project WP-00018 Department of Civil Engineering Univers i ty of 1 1 1 inoi s Urbana , 1 1 1 i no i s November, 1965 m W in i zz j en J > FATE OF SYNTHETIC DETERGENTS IN SOIL AND GROUND WATER by Shankha K. Banerj i and Ben B. Ewing Final Report September 1 , 1959 through January 31 , 1 965 Supported by Division of Water Supply and Pollution Control U.S. Publ ic Health Service Research Project WP-00018 Department of Civil Engineering University of Illinois Urbana , 1 1 1 i noi s November, 1965 -,- ,,' ENGINEERING LIBRARY i i i ABSTRACT The microbial population in the top layer of soil in either aerobic or anaerobic conditions provided surface for the adsorption of ABS which was desorbed easily by de te rgent -f ree water. There was little indication of ABS biodegrada t ion by the microbial slimes in the soil systems. Various soils (silicious, calcareous and clayey soils) had significant ability to adsorb ABS under both batch and percolating systems. The equilibrium adsorption of ABS on these soils followed the Freundlich isotherm. The amount of surface area covered by ABS under equilibrium conditions with clayey soils was small (0.2 to O.k per cent for bentonite), whereas with Ottawa sand there was an indication of multilayer adsorption. Adsorption of ABS on the bacterial cells in batch activated sludge units was determined for cultures grown on three substrates; i.e., maltose, dextrose and Metrecal. B iodegrada t ion was noticeable in these activated sludge studies and was especially high with the complex substrate (Metrecal) units. Intermittent sand filtration was investigated as a means of tertiary treatment for removing ABS and phosphates from wastewater treatment plant effluents. Hydraulic loading on the sand filters, the dosing intervals and the waste characteristics were the variables investigated. Adsorption and bio- degradation were both important in the removal of ABS and phosphates by the sand filters, but neither was effective in reducing the amount of these material after a few weeks operation had resulted in saturation of the filter column. VI vi i ix xi xi i TABLE OF CONTENTS Page ABSTRACT iii ACKNOWLEDGMENTS LIST OF TABLES LIST OF FIGURES ORGANIZATION OF THE REPORT PERSONNEL I. INTRODUCTION 1 II. REMOVAL OF ABS BY BIOLOGICAL SLIME ON GRANULAR MEDIA 3 I I — 1 . D i scuss ion 1 III. ADSORPTION OF ABS ON SOILS 14 I I I - 1 . Effect of Particle Size and Surface Area 16 III-2. Effect of pH 22 III -3 - Effect of Minera logical Composition 22 III-4. Effect of ABS Structure 2k III -5 • Discussion 36 IV. REMOVAL OF ABS BY BIOLOGICAL FLOCS IN ACTIVATED SLUDGE SYSTEMS 42 IV - 1 . Procedure 43 IV-2. Results 47 IV -3 • Discussion 53 V. TERTIARY TREATMENT OF ACTIVATED SLUDGE PLANT EFFLUENT FOR ABS AND PHOSPHATE REMOVAL BY SAND FILTRATION 60 V-l . Procedure 60 V-2. ABS Removal 66 Page V -2.1. Results 66 V-2.2. Discussion 75 V-3. Phosphate Removal °2 V-3 . 1 . Results 82 V-3. 2. Discussion 95 VI. CONCLUSIONS 101 /II. BIBLIOGRAPHY ] oZ+ VI ACKNOWLEDGMENTS The research reported herein was supported by Research Grant WP-00018-05 from the Division of Water Supply and Pollution Control, United States Public Health Service and was carried out at the Sanitary Engineering Laboratory of the University of Illinois. Most of the radioactive a 1 ky 1 benzene sulfonate was furnished by the California Research Corporation and special samples of a 1 ky 1 benzene sulfonate, both labeled and unlabeled were provided by the Colgate Palmolive Company. Samples of silica were contributed by the Ottawa Silica Company. We wish to thank Dr. John P. Kempton of the Illinois State Geologica Survey for the supply of many of the soil samples and for his advice in their identification, and Dr. Walter Parham, also of the Illinois State Geological Survey, for preparing and analysing X-ray diffraction patterns of the soils. We also wish to thank Dr. R. S. Engelbrecht and many others at the Sanitary Engineering Laboratory for their helpful suggestions and advice. V I I Page 7 15 19 25 27 LIST OF TABLES Table No. Title 1 ABS Uptake on Solid Phase in Closed Columns A, B, C, D, E and F 2 Grain Size, Shape, Density and Surface Area of the Soi 1 s 3 ABS Adsorption on the Soils at Concentrations of 5 and 16 mg/1 k ABS Adsorption on the Soils ABS Adsorption on S i 1 ty Clays in Batch Studies 6 ABS Adsorptions on Siliceous Soils in Batch Studies 28 Comparison of the Values of 'a' and 'n' of the Freundlich Isotherms for Different Soil -ABS Systems 30 8 Adsorption of ABS in Saturated Columns of Glauconitic Sandstone 32 9 Adsorption of ABS in Saturated Columns of Mi ss i ssippian Sandstone 33 10 Adsorption of ABS in Saturated Columns of Ottawa Sand 34 11 Reduction of Base Exchange Capacities of Clayey Soils due to Adsorption of ABS 37 12 Details of Operation of Batch Activated Sludge Units kk 13 ABS Removal in the Activated Sludge Systems 5^ )k ABS Adsorbed on the Microbial Cells in the Various Activated Sludge Systems 55 15 Freundlich Isotherm Constants, 'a' and 'n 1 for ABS Adsorbed on Cells 56 16 Column Packing Data for Tertiary Treatment 62 17 Champa i gn-Urbana Activated Sludge Plant Effluent Characteristics Summer 1963 64 V I I I Table No. Ti tie Page 18 Loading Rates and Feeding Schedules for the Six Columns for Tertiary Treatment 65 19 ABS and COD Removal in the Sand and Gravel Columns in Tertiary Treatment of Activated Sludge Plant Effluent 67 20 Cumulative ABS Removals and the Amount of ABS Eluted from the Columns 73 21 Variation of Moisture, Volatile Solids and Bacteria Counts in the Columns with Depth of Sand 77 22 ABS Desorbed from Sand in Column 5 83 23 Average and Standard Deviation Data of Phosphate Removal by Sand Columns 8k 2k Total Phosphates Removed and Amount That Can Be Eluted 87 25 Phosphate Removal Before and After Elution 96 I X LIST OF FIGURES Figure No . Title Page 1 Schematic Drawing Showing Construction of C losed Col umns 4 2 Breakthrough Curves for Column C 6 3 Line Diagram of Open Column 8 4 ABS Breakthrough Curve for Open Column 9 5 Change of Soil Surface Area with Grain Size 17 6 The Change of ABS Adsorption with Concentration 18 Intensity of ABS Adsorption at Concentration of 5 mg/1 20 8 Change of ABS Adsorption with Soil Surface Area at Concentration of 5 mg/1 21 9 Variation of ABS Adsorption on Ottawa Sand with pH 23 10 Freundlich Isotherms of Mi ss i ssi ppian Sandstone 29 11 Breakthrough of Chloride and ABS in Saturated Columns 2A £■ 5A of Mi ssi ss i ppian Sandstone 35 12 Relationship between Percentage Reduction in B.E.C. and ABS Adsorption 38 13 Experimental Activated Sludge Unit 45 14 ABS Distribution in the Dextrose Activated Sludge System 48 15 ABS Distribution in the Maltose Activated Sludge System 49 16 ABS Distribution in the Metrecal Activated Sludge System 51 17 ABS Distribution in Maltose Activated Sludge System with Dextrose Substrate 52 18 Freundlich Isotherm for the ABS Adsorption on Cells in the Activated Sludge Systems 57 Figure No. Title Page 19 ABS Distribution in the Liquid and Foam Phase in the Activated Sludge Systems 59 20 Line Diagram of Sand Column 61 21 Comparison of ABS Removal and the COD Removal in the Sand Columns 68 22 Effect of Hydraulic Loading on the ABS Removal by the Sand Columns 70 23 Cumulative ABS Removals in Columns 1, 2 and 3 71 2k Cumulative ABS Removals in Columns k, 5 and 6 72 25 Elution of the Columns with Tap Water for ABS Desorption Jk 26 ABS Removal of Column 5 Before and After Tap Water Elution 76 27 Evaluation of Moisture, Volatile Solids and Bacterial Density in Sand Columns 78 28 Comparison of Total Phosphate Removal Between First and Second Period 86 29 Cumulative Total Phosphate Removed by Column 1 88 30 Cumulative Total Phosphate Removal by Column 2 89 31 Cumulative Total Phosphate Removal by Column 3 90 32 Cumulative Total Phosphate Removal by Column k 91 33 Cumulative Total Phosphate Removal by Column 5 92 3k Cumulative Total Phosphate Removal by Column 6 93 35 Elution of Columns with Tap Water 3k 36 Elution Curve of Column 5 97 XI ORGANIZATION OF THE REPORT In presenting this final report, the results and conclusions of the previously published material have been summarized in Chapters II, III and part of V. The unpublished materials presented in Chapter IV and part of V have been dealt with in greater detail. The following publications were made under the sponsorship of the research project which was used in making this final report: 1. "Synthetic Detergents in Soils and Ground Waters," Progress Report, September 1, 1 959 to November 30, I960. RG-656O, Submitted January I96I. 2. "Effect of Biological Slime on the Retention of ABS on Granular Media," Banerji, S. K., Sanitary Engineering Series No. 10, University of Illinois, Urbana, Illinois (Jan. 1962). 3. "Effect of Biological Slime on the Retention of Alkyl Benzene Sulfonate on Granular Media," Ewing, B. B. and Banerji, S. K., Proceedings of the 17th Industrial Waste Conference, Purdue Univ., Engineering Extension Series 112, 351 (May 1 962) „ 4. "Effect of Soil Properties on the Adsorption of Alkyl Benzene Sulfonate," Suess, M. J„, Sanitary Engineering Series No. 14, University of Illinois, Urbana, Illinois (Jan. 1963). 5. "Effect of Chemical Composition of Alkyl Benzene Sulfonate on Adsorption by Soils," Ghosh, S. N., Sanitary Engineering Series No. 16, University of Illinois, Urbana, Illinois (June 1963). 6. "Removal of Phosphates in Secondary Sewage Treatment Effluent by Sand Filtration," Hsu, C. C., Sanitary Engineering Series No. 23, University of Illinois, Urbana, Illinois (May 1964). 7. "Retardation of ABS in Different Aquifers," Suess, M. J., Journal Am. Water Wks. Assoc, £6, 89 (Jan. 1964). 8. "Surface Area Measurements and Adsorption of Soils," Suess, M. J., Journal Irrigation £■ Drainage Division, ASCE, Sj, (March 1964). 9. "ABS Adsorption on Soils," Suess, M. J., Journal Water Poll. Contro' Fed., 36, 1393 (Nov. 1964). XI PERSONNEL The Principal Investigator, Dr. Ben B. Ewing, was in charge of the project throughout the tenure. Over the five-year term of the project, there have been changes in the personnel in the research assistant level. The following personnel were associated with the research project: Mr. L. W. Lefke, December 1959 to June 1961 Mr. S. K. Banerji, September 1 96O to August 1964 Mr. S. N. Ghosh, September 1 96 1 to June 1 963 Mr. M. J. Suess, September 1 96 1 to February 1 963 Mr. C. C. Hsu, September 1962 to June 1964 Various other temporary hourly employees also helped in carrying out the objectives of the study and their contribution is sincerely acknowledged. I. INTRODUCTION Use of synthetic detergents has increased in recent years so that 90 per cent of the household detergents are synthetic in nature (1). This conversion of cleanser has caused a number of detrimental effects on waste- water treatment. The first effect noticed was the foaming of sewage plants, streams and rivers. Poor gas transfer during aeration was attributed to syndets (2). Even secondary settling was found to be affected by the presence of detergents in the sewage treatment plant (3). The biologically resistant nature of these syndets was a contributing factor in these ill effects in sewage plants. The packaged detergents consist of: 1. a surface active agent or surfactant, which is about 10 to 15 per cent of the total volume of syndet, 2. phosphate builder compounds, about 30 per cent in ortho and condensed phosphate forms, 3. miscellaneous builder compounds, k. perfumes, 5- colors, etc. The present study involves mainly the surfactant, and to some extent, the phosphates. The most common surfactant used at present is the sodium salt of al ky lbenzenesu 1 fonate (ABS) , This surfactant was found to be biologically resistant in the normal waste treatment processes due to the branched structure of the tetrapropyl alkyl chain (k, 5). Recent advances in biodegradat ion tests on surfactants have shown that straight chain molecules are 90 to 95 per cent biodegradable under normal aerobic treatment processes (5, 6). Manufacturers of detergents have voluntarily developed a more biodegradable linear alkyl sulfonate (LAS) (6). These surfactants made their debut in June 1965. The studies re- ported herein were conducted on the branched ABS, but because the physical and chemical nature of the new LAS is similar, much of the results will be equally appl icable . The first groundwater pollution by detergents was reported in 1958 (7), although their use was on the steady increase since 19^+8. Subsequently there were several reports of groundwater pollution attributed to detergents (8, 9 S 10). Most of these instances were in suburban areas where each house had individual wells as the water source and used septic tanks and tile fields or cess pools for waste disposal. The public health aspect of the detergent in water in concentra- tions as found in these wells was not significant, but the presence of other pollutants accompanying these detergents was the real danger. In fact, Walton (10) and Nichols (11) considered the presence of ABS a good indication of sewage con- tamination of ground water. The syndets moved much more slowly in the ground than did the water or other chemical pollutants (2). In most cases Walton (10) found wells contaminated by ABS to be within 100 feet from the source of pollution. The slow movement of ABS in groundwater was also observed in Mastic, New York (12) where the rate of movement was, on an average, 0.25 feet per day. The objective of this study was to evaluate the relative importance of several factors on the retarded movement of ABS in a soil system receiving a waste containing detergent and to evaluate the fate of the phosphate builders in the soil system. The role of the biological slime which may develop in the top layer Q f soil and which may provide additional surface area for increased adsorption of ABS and phosphates was investigated. Also, in this zone, the slow percolation rates may allow enough time for b iodegradat ion of both the ABS and phosphates. Deeper soil layers may retain the detergent components by ad- sorption. Environmental factors affecting this retention include the type of soil, concentration of solute, structure of solute, pH and temperature. II. REMOVAL OF ABS BY BIOLOGICAL SLIME ON GRANULAR MEDIA (13) In order to study the removal of ABS in anaerobic saturated flow conditions, six columns designated A through F were prepared by uniformly packing 2-inch diameter 36-inch long glass tubes with Ottawa sand. The geometric mean size of this sand was O.858 mm. The feeding arrangement and other details of the column are shown in Figure 1. The columns were so constructed that they could be dismantled in half and sterilized in an autoclave. Columns A, C and D were seeded with settled and filtered sewage to allow a mixed microbial population to develop in the column. Synthetic waste containing 300 mg/1 dextrose and other necessary nutrients were later fed to maintain an active microbial population in the column without clogging. The BOD removal between the influent and the effluent to the columns was taken as an index of biological activity in the columns. Columns B, E and F were clean sand columns which served as the basis of comparison for ABS retention due to s 1 ime growth . 35 Sulfer-35 was used to label the ABS (ABS ) which permitted radio- chemical analysis in lieu of the compleximet r i c technique using methylene blue (14). This avoided much time-consuming chemical analyses and interferences 35 in the determinations. ABS solution of the appropriate concentration was introduced with the regular feed solution for columns A, C and D. Columns B 35 15 and F were fed ABS with distilled water and column E was fed ABS with tap water. The reason for using tap water was to see if there was any difference in ABS retention in the column because of the salts present in the tap water as compared to distilled water. 35 The ABS breakthrough curves for each column were found by determining the activity of the effluent samples until the effluent activity was the same as rQ r ^^^WtAv w^^^W GLASS FEED TUBE f^ 2 RUBBER STOPPER GLASS WOOL MAT EARTH MATERIAL CENTER KEY FLANGE JOINT /J GLASS WOOL MAT M^«mn»i'i..>rfi TlfYV-lir-i iiTnri i J PYREX PIPE ALIGNING KEY TEFLON WASHER DRILLED LUCITE PLUGS GLA SS DRAIN TUBE Figure 1 „ Schematic Drawing Showing Construction of Closed Columns that of the influent. The breakthrough curve for column C is given in Figure 2. The pore volume was determined by chloride tracer breakthrough which is also shown in the figure. The other breakthrough curves are not reported here and can be found in an earlier publication (13). Prior to operation, column D was sterilized in an autoclave at 120°C and 15 pounds pressure in order to kill all 35 microbial populations. The ABS retention in these circumstances was to be compared with that on the column in which an active microbial population had been developed. 35 The ABS retention in various columns was calculated on the basis of the breakthrough curves. The area between the chloride breakthrough curve, 35 which represented pore volume, and ABS breakthrough curve represented the 35 ABS retained on the solid phase of the soil. After the ABS breakthrough had occurred, the sand was removed from the column for ABS desorption tests by a method developed by investigators at Robert A. Taft Sanitary Engineering Center, Cincinnati, Ohio (15). The microbial population, volatile solids, and moisture content of the sand at different depths were also determined for the biologically 35 active columns. Table 1 presents the ABS adsorption data for all the columns. 35 All attempts to show ABS b iodegradat ion in the biologically active columns were negat i ve . The study was continued in an unsaturated biologically-active aerobic column. Figure 3 depicts the details of construction and operation of this 35 column. The synthetic waste containing 10 mg/1 ABS was intermittently intro- duced to the column by a siphon arrangement. The breakthrough curve obtained for this column is represented in Figure k. The pore volume was determined by measuring the water required to saturate the column and then the column was drained and dried for use. The ABS retained per gram of sand was 22.47 micrograms, even though the effluent indicated the column was not completely saturated with ABS. OJ — o o z LU r> _j u. lx UJ z _l O o o N0I1VM1N30N00 1N3P1JNI NOI1VHUN30NOD lN3nidd3 H o o u o < o / LUCITE DISTRIBUTOR PLATE WITH 16 No. '/8 HOLES I 'm H ii ii ii i i S A N D GRADED GRAVEL 3/8 DIA. GLASS VENT TUBE LUCITE OUTER SHELL 14 .2 cm EFFLUENT COLLECTOR Figure 3. Line Diagram of Open Column o o o CO o o o CO H o o d a> p< o u O ■ •w E — CJ L. 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The latter gives the total area including internal surfaces of particles, whereas the former method gives only the external surface area. The ABS used in this study was dodecyl benzene pa rasul fonate-sod ium 35 salt having a molecular weight of 3^+8.0 and was tagged with S for ease of analytical determinations. Batch techniques were employed for determining the 35 adsorption of ABS on the soils. ABS concentration varied from 9-64 to 53 rng/ 1 . The liquid was separated from the solid phase by centr i f ugat ion after different 35 periods of contact. ABS activity was determined in samples of supernatant liquid. This was continued until equilibrium between the ABS adsorbed on soil and ABS still in the liquid phase was attained. Equilibrium adsorption iso- therms were plotted according to the Freundlich equation in Figure 6. Table 3 35 shows the soil surface area and ABS adsorption relationship at two different ABS concentrations, 5-0 and 16 mg/1 . 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CD c ro 4J o •— • — 4-J i_ i c O " CD CD 1— 1 in Q. 20 J [ ! 1 8 1 ' 1 ! 1 1 1 1 1 | 1 I 1 III 1 I 1 1 1 - _ t3 - e CO 10 — (0 3 CO *-> 8 CM O in 8 o BO CO CM •M O.HH <« E CO • o ■ Hi _ . •t-4 CO CO _ - ♦J 1-t -H (0 c - ~ 1— < to CO k o •* > — \p >» £ c \ 4> — O Q 0- — 1®, ©\ a >» — ' H-t oo 8 \ CO ~ oo \ •—* i— t E fH t-t CM u CO •«■« >»•-< O co c *» HI •T4 ft eo mH 4-> u - > 3 CO 4* 8 o 0) " ?•» T-S O © \ a. 09 — tO o «-> — S J= CO 3 c ^ \ G f* _ c »> CO CO r-t 0) f* »— ( »H a. ft — flu as >, O H"t ~ to e c M © 0) •IH — 0> flu e co a B O <-» B CO > ;►» (A E e \© - 0* - - - J U. 1 1 1 1 1 l.i'. (III l III 1 1 1 1 1 IS ©CM -8 8 _ o — in E in o § CO ♦* t-< o o I ♦J B CO o ~4 B +J O Cl «*-« M > CQ «■* < (O >» B ♦■» M •*« to B 0) ♦* 3 o o s in 21 3iii I r i — r TTTT CO V CO o a> cu 8 S 8 \ •f-t c CM \ Wt 3 CO £© *> 1 e CO > •rt , o» l—t B \ •»■' >> o \ K CA o© A-) c c CO 3 o CM CD a. o o 8\ \ ° l—t CM B CO o t—i v") f+ •*1 M Q. 4-> Q. •f« C •r* »— 1 CO o \ (A o 1-< r- \ (A o c i-i CO i-* \ CO > hH \ £• (A >» C \ ^ s (A CO \ * c •^1 \ c c c CD CO a. > 1— » >> V) c c CU a. 8 "O B CO (A CO 2 CO ♦J OS B in o CD CM u E co «M in t/5 3 1 (A CO »— < 0) •^ u o CO w CO •«-< «M 3 »4 s B C/l O t—i ••H Q. U o (A in ■o • CO o V3 OQ < OJ B CO J3 «— i o I I 1 1 I I J L I I I if) o CO CD u 3 o ~* 8 8 o 6/67/ v - uondiospv 22 surface area measured by the glycerol method. This once again showed that although adsorption increased with an increase in surface area it was relatively lower on materials with a high specific surface like clays when compared to materials like sand or sandstones which had low specific surface area. III-2. Effect of pH The dependence of adsorption on pH was quite logical since it is known that the ionization characteristics of solute and solvent changes significantly with change in pH . The study involved the use of only one soil, Ottawa sand. The pH range covered was from 3-2 to 9-2. The ABS used was dodecyl benzene parasu 1 fona te-sod ium 35 salt which was tagged with S as indicated earlier. The procedure involved the addition of a known amount of Ottawa sand in a polyethylene centrifuge tube con- 35 taining the pH buffer solution which already had ABS solution of appropriate concentration in it. After periodic shaking, the tube was closed with a rubber stopper and aliquots were removed to determine the ABS concentration of the supernatant; no centr i fugat ion was necessary because Ottawa sand was easily separated by settling. After seven weeks of contact, the sand was separated and the ABS was desorbed by the procedure mentioned earlier (15). This procedure was followed because it was found, in an earlier exploratory experiment, that polyethylene tubes adsorbed significant amounts of ABS. Figure 9 shows the 35 effect of pH on ABS retention on Ottawa sand. The ABS retention increased with decreasing pH at all three contact periods. III-3. Effect of Minera logi ca 1 Composition (21) Adsorption of ABS in an underground aquifer will certainly depend on the type of minerals in the water-bearing rock. This variation of mi nera logi ca 1 23 c CO (TJ 3 o < < 4-1 15 <0 CTv 0) u 0> iu6/ui6rl 'uojidjospv S9V Ik properties of the soil on the ABS adsorption was studied. The soils reported in Section III were used. The study involving these soils was conducted in batch experiments as 35 described in Section III-l using dodecyl benzene parasu 1 fonate tagged with S These results are summarized in Table 4. The data show that clay materials ad- sorbed more than the other soil mater ia 1 s; th i s was perhaps due to higher surface area per gram of material rather than to mi nera log ica 1 properties. Ground lime- stone was found to be adsorbing more ABS than sandstone for the same grain size particle. This fact was not very significant because in actual limestone aquifers, water flows through fissures and crevices, and the surface area exposed would be very much lower than a sandstone aquifer. Among the limestones it was observed that the Oolitic limestone adsorbed more than the high purity limestone, although both had high calcite. The glauconitic sandstone had a higher adsorptive surface area than the other sandstones as measured by the glycerol method. This was not evident in the ABS adsorption, which was about the same as in the Mi ssi ssi ppian-age sandstone . III-4. Effect of ABS Structure (23) This study involved all the soils mentioned in the earlier section except the calcareous materials and the Pennsy 1 vanian-age sandstone. The difference in the composition of the ABS used was two-fold: firstly, the a 1 ky 1 chain length was different, and, secondly, the variation in a 1 ky 1 chain length differed. Four kinds of ABS formulation were studied. Two pure compounds, viz., sodium 1 -propyl nonyl benzene pa rasu 1 fona te (herein referred to as C-12 pure) and sodium 1-propyl dodecyl benzene pa rasu 1 fonate (herein referred to as C-15 pure) were compared to show the effect of chain length, or molecular weight. 25 o o CO LA C7l E crs, 03 C7) o E en en 3. a L. l/l -a < CO CO < -3" 11 A 03 4-j crs. 3 03 en i — o E o o CO o LA (1) PA 03 cn c QJ U c o o o CO vO cn zL a> cn o E cn cn 3. -4 j: _ ex's 03 cn o E cn cn 3. 03 O oo CO CM is CN cn CM o CM PA vA — CA O CX) LTi- LA MS CA ' — O CA -4 CA — PA PA CM — — CO LA LA LA -4 OA \fl IS N IS csl ■ — LAO VO N vO CA CO CA CO CA LA \i) rs — -4 rs j- v£> LA J" CA O SvD rs is CT\ O CO ' -4 rs cn o o vo CO CM O LA LA O LA CA-4 O CM — — — IS O O CM LA — rs o O CM \0 CO -4 CM OO LA rs v£> CM CO o rs cm — -4 CO CO LA LA CA i — is AvD eg tv^ rs CA CA LA -4 -4 CM O CO ca CA PA CA CA co LA -4 rs CA O CA CM vO CO is LA CA — \£> LA LA O rs rs PA PA -4" LA LA pa cm rs j- rs CM -4" CM CO CM -Cf J- CM — — rs LA vD CO — rs mo 00-4 -4 — — CA — PA PA CM CM CM PA PA o o o o c o o rs o o 03 o CM — CM D. CM is cm is O -4 O CM CM J" PA is CA LA CM LA ^O IS4 CA-4 vO CA pa CA rsco — -4 CM CM CA — PA LA O CO IS LA CM — LA rs O O O O CO — CA CM \£> LA LA PA CACO is CM CM CA is LA J" — CM -4 LA CO — O CA CA IS — ■4- — rs cm CM LA CM PA PA PA a) 03 1— 1 c in C (-H o 4-1 03 o 4-1 03 o> 1/1 •— in 03 cn cr> XI i_ 03 C T 03 c 03 E o 1 03 4-J • — 4-1 c c in 03 i — c/3 L. 03 03 E 0) X> 13 • — 03 • — 03 o s E c O Q. c c C • — in 4-J »_ 03 ■ — Q. o > •M o !_ 4-1 in 1/1 1— l/l c 03 3 o • — 03 03 C/l ■a >-"0 o !_ O- • — 03 c 3 o .— c in c o 03 1 4-J in 4-t o 03 • — in ij C 03 D O -C • — > 4-J 4-1 • — in 1/3 c in 03 " — cn i — 03 ' — c 4-J ■— •— 0) ' — 03 •— o ■ — ' — 03 O CO s: a. C3 O z: o O H-l DQ CM CM — CM O — . — — -4 VO PA CA r— ' CA O CA CM CM GO PA PA CM PA CM CA O — — CM -4" PA CA 00 O CA CO vD LA LA C C c 03 03 03 Q. Q- O- o in T3 03 oo CO < c o 4-J 03 !_ 4-J c 0) u c o o E L- D CT 03 II O 26 Commercial detergents utilize a 1 ky 1 benzene sulfonates composed of a blend of compounds varying in a 1 ky 1 chain length, however. Therefore, two such blends were compared. One consisted of sodium a 1 ky 1 benzene pa ra su 1 fonate , with a 1 ky 1 chain lengths varying from 8 to 19 carbon atoms but averaging 15 carbon atoms (herein referred to as C-15 blend). The other was sodium alkyl benzene pa ra - sulfonate, with alkyl chain lengths varying from 7 to 18 carbon atoms but averaging 12 carbon atoms (herein referred to as C-12 blend). Further, in these blended formulations, not only was there a variation in the chain lengths, but there was also a variation in the position of the benzene ring attachment to the alkyl chain. The majority compound in both cases was the 3 _ phenyl type. However, in the pure compounds the attachment of benzene was on the 4th carbon in the alkyl cha in. The method used to determine the effect of structure of ABS on Its 35 adsorption to soils consisted of placing ABS solution in a container with a known weight of soil. Periodic shaking of the container provided intimate contact between the soil and the ABS molecules. Portions of supernatant solution were withdrawn at different time intervals until an equilibrium had been established 35 35 between the soi 1 -adsorbed ABS and ABS in the liquid phase. For some soils, centr i fugat ion was found to be necessary to separate the soil from the solution. 35 This process was repeated with eight different ABS concentrations of each ABS type, for all six types of soil. Tables 5 and 6 present the ABS adsorbed in 35 these soils and the corresponding equ i 1 i br i urn ABS concentration. Adsorption isotherms were plotted from these data. A typical Freundlich isotherm for the Missi ss ippian-age sandstone is shown in Figure 10. The trend of other soils was similar when the relative adsorption of different ABS's were compared. The values of 'a' and 'n' i n the Freund 1 i ch i sotherm: Loq — = Loq a + — Loq C , a re shown i n 3 m 3 n Table 7. It has been reported by Adamson (2k) that 'a' is a measure of the surface 27 -o CO U CO CQ l/> >• O co O in ■o < co CQ < I .Q .— E c . — O O • — — c 3 i- o CT o UJ -o c Q) 1 r-^ Cu E JO L. c en o o ^ l/l .- CO LA T3 4-> i i — < 1 — ' O T3 c — 0) c o> Li_ O E C_> x — ' ■o cj a) I/) CM I .- S c — — o o " — — c cfl 3 1- O E O" O a e L. c Cn o o ^ in — en to 4-) ri < — ' "O C — E o_ 'eT L. C CO o o v i/> •— cn -o 4-> ri < - ^ -o c — v -^ I _Q • «—. — EC — — 3 U ^ — — c ol 3 s- o E cr o '"— o- E i- c en O O ^ i/i .— en -o -t-i i < v -" c — O ^ c en O E — CM -d" vO -NJ- NO O - (^ — CM -d - vO — cm -d" r»» o o — Cn — CM J" v£> vo -d- oo -d- r-v-oo — PALALACM U\Ov04 pa Cn o vO -d - vO lacm O — CM J- \fl rv. (VMA — PA LA OO — CM-rfO— vO — CM PA oo — cM-d" — — -d" — CM PA — pa -T CO CM 00 LA vO \£> v0 I-- O O CM LALA CM vO Cn 1 — — -d" Cn -d" — CM LA Cn LA JvO-JOO soco CM-5 — LA— r^OCTN — — CM J" O LA OOOLAOOLAO OOOLAOOLAO OOOLAOOLAO — CNj-Tl-^OJ-f^-LA — cm -d" r^ — CM -d" vO O -d" r>~LA — cm -d- r»- — CM-rfMOO-d - MA — cm J- r-». r^ co la r*~ r-~ r-« cm paOmO Cn -d" la— PA pa — oo -d" la cn oo r^ — CM LA r-» CM 00 CM — — pa O — — CM-d'OOvOO — PA o — — pA-d-co r-^-d - — PA pa — CO O lamO — -d" CM r — CM LA — CM CM O O PA LA — -d - - vOCO — — PA LA CM r^r^cM ooo ovOmo CM LA Cn PA O (TtO — pa -d - — 00 O LA O Lf\ O LTV — CM/\OOvD O CM ■ — ro ^x> LA00OLAOLAOLA LAOOOLAOLAOLA O — PALAOOvOOCM — PA VO O — PALAOOvOOCM — PA MD vO m4vO ON n — PA LA 00 CM PA-d" N NvD f^-t ^O O PAPAPAr^OOvOOO CM O O O O — — PA J - OOOOO — — CM CM CM CM (T\ 00 ' — — — PA CO CA CT» LA CM CT\ cMLAOCnO-d"CMO CM LA— Cn pa O 00 MD — — PAsO CM

-C o CO CD o 3 o u o X < QQ < X (A 1/1 X C 3 o e o c_> CO < la XI • " - .- e c — — => o ^ — —CO" a <- O E cr o >— a. •- c o o ul — X 4J < E en en 3. CN o X C — C CO u. O E <_> "■ — I _Q ■ ^-« - E c — — 3 Q. l. c in — X) J- 1 < C O" O E o "— E Cn cn 1 X C — O O "v. (/I .- CD D «J 1 X C — c — o ^ C CTj O E o Q- E i- c cn o o -^ in — cn x -t- 1 3. < v -' X C — 0) U \ 1) C O) i-^ O E o E M- — ». pa vO NroO o O 1 — PA -3" LA — PA O — CN J" O — CN PA LA O O vO — CN PA O oo pa LA LA CN p»> CN LA LA PA CN LA CN CO LA PA • PA vO -3" 00 CA CN LA PA-d" O vO CN 00 CN — — PA vl> CA -d" sO -d - -d - CO -d - r^ LA (M N N \J) vO N N ' PAOO CN o LA CN O -4" O LA O LA r^ o o — — CN -d- o • LA O O LA O LA O o LA O O LA O LA O ~ i cn -d - r-v o o — C"\ — CN -3" vO _ N4 NO O - 0\ — CN -d" vO 00 r---d- CN O CO O LA LA GO -d" -d - -d" LAP^vO p*. vj3 O cn la O O O o PA LA CO cx» CN -d" 00 oocN^j-^or^oo^A — PA \^ o i— PA LA r-*. O 0"\ VJD CN PAxO ^D MD CNJ CO CN CN O 00 CN •d- n£> PA CO PA CN LAOOOLALAOO CN -3" 00 r»» pa O O CN PA-d - CN CN -d" O CN SroO CN PA LA CJ"\ \0 CN -d" — PA CN o o O LA O O LA O OOOLAOOLAO O O O LA O O LA O «— CM J" sO o -3" r-» — CN -d- LA -(Mj-vooj-rvin — cn -d- r-v *"*" N4 - vD OJ- MT\ — cn -d- r>. 1 1 1 1 1 1 1 i i i 1 1 1 1 1 1 -d--3"PACNCNCO-3"-3" -d" pa o co pa r^ o o 1 O — CNJ-LAOCAO -d- o — CN PA LA O O 00 — CN PA 1 1 l 1 • 1 1 i i 1 1 1 1 1 PALACN O NNM4 — PA v£) O — *— PA — CN J" 00 LA CT\ O P*> P-. v£) vO LA -J- NONOCO — cn -d" Cn 1 1 I • 1 1 1 i i i 1 1 II 1 1 1 1 LA00OLAOLAOLA l-AOOOLAOLAOLA 1 O — PA LA 00 *-D O CN ' — PA VO o — PA LA CO O O CN — PA v£> 1 1 1 i 1 1 N(N NvO(TlOO O , 1 » — O PA O v£> O 1 l 1 i 1 1 1 OOOOOcnOO — CN 1 i — pa o -d- 1 1 1 1 1 l 1 i 1 1 1 1 i i i 1 1 1 I 1 1 1 ! OLALAOOOOLA CN lAO O LACnr-- — — CN PA LA CT\ PA 1 1 1 1 LA O LA O LA O 1 CT\ CT\ PA LA 00 v£) — PA LA CO LA 1 1 1 1 i 1 1 1 1 r-»LALALAOOOO 1 1 LA LA O O O O 1 1 i 1 1 1 O — PA LA O f--. LA PA — — PA LA 1 1 PA LA O f*-- LA PA — — PA LA 9uo;spue$ auoispues pues eMeilo ueidd i ss i ss i w d i } juooneo 0.2 1 10 Equilibrium Concentration, mg/1 Figure 10. Freundlich Isotherms of Missi ssippian Sandstone 30 l/l E L. 0) 4J l/l t— 1 X u • — . — X C 3 0) 1_ l/l Li. E QJ X i/l i-t >- 00 y- CO CO - < c i XI O c 00 10 4-1 - c TO *. > 0) X 4- M- o c l/l 2. E O CJ C TO 1/1 — o CO 0) t/> a 3 > o \- OJ o co •— 00 •— < CO a> a > i- — •_ o CO c TO l/l ""■ o a> CO a > > i- OJ >• co TO CO — < (_) a> a. > i- — o co o p»» r-» en o OO LA P>- p^ ^ ca J- CM 00 CM r~« CM 00 CM o o o CM o CM • vO 00 r*» CA 00 CA -d- vO 00 — — P^ CM CM — XI XJ XI X X X c c OJ c c OJ OJ c c OJ u a> L. a) OJ L. U OJ OJ t- < — »— 3 -— ^ 3 3 *— — 3 X X a. XI XI a O- X X O. * — ' — ' N ~' **■" *— • ' — ' 1 — ' w ' *— ' la CM CM LA CM LA CM LA CM LA r— »— •^ *— -— ^— ^— ^— *— o CJ CJ CJ 1 a C OJ c o O o 4-1 c CJ a> c o 4-> CJ TO TJ i/> c TO TO 4-1 /I •— TO *— t/> o z: i/) O r-* en LA r^. -3" \o r»- O LA PA LA CA la r-- O vO i-^ CM CT\ LA ca — a> **— o "~~ O o ^~ ^~ d O d •""" o r»» CXi CT\ CM CM CA o r-» $ vO vO LA oa *— oo LA 00 PA CM vO CM CM CM LA XJ XI X X X X 0) c c oj 0) C c OJ OJ c c OJ L. oj 0) i_ l_ 1— 1 O CJ O O OJ 4J C o 4-> c OJ CO (_) CJ 31 area of the soil under a monomo lecu 1 ar layer of coverage of the adsorbate and it measures the potential capacity of the soil for adsorption. The values of 'a' obtained in the experiment provided a good comparison of ABS adsorption on different soils and it was evident that: 1. C — 1 5 blend ABS was adsorbed more than the C-12 blend compound, 2. C-12 pure was adsorbed more than C — 1 5 pure, 3. C - 1 5 blend was adsorbed more than C - 1 5 pure, and lastly, k. C-12 pure was adsorbed more than C-12 blend. In order to confirm the batch data, several columns were prepared with the glauconitic sandstone, the Mi ss i ss i ppian-age sandstone and Ottawa sand. Clayey soils were not used because of their low permeability in columns. The 35 ABS used were the pure dodecyl and pentodecyl compounds. The precedure used 35 for determining ABS adsorption on these soils was exactly the same as described 35 in Section II. ABS breakthrough curves were obtained and the area between the 35 ABS breakthrough curve and the chloride breakthrough curve represented the ABS retained on the solid phase. Tables 8, 9 and 10 present the ABS adsorption in 35 the column experiments. Figure 11 is a typical ABS breakthrough curve obtained for the Mi ss i ss i ppian-age sandstone. None of the columns was completely saturated with ABS, although at some points indications were seen of very nearly complete breakthrough. At these points, static contact for several weeks allowed further ABS adsorption. The study was suspended even before complete breakthrough occurred because of lack of time and pure ABS compound. The results also showed that the pure dodecyl ABS was adsorbed more than the pure pentadecyl compound which confirmed the batch experiments. From theoretical calculations of ABS monomolecu lar layers, it was found that only 0.31 per cent of the area of bentonite was effective in adsorbing ABS 32 C o 4-1 •o c CO co c o o 3 CO a i/i c E O <_> ■o 01 — dL 4J o ■^-^ O o (- 0> (/I 4-J a; oS E "n. 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CO co ca < a. L. o (/I < co 00 < en. > i o o II CA J" S^ o oo . en o v — O O ID cn in 4-4 ^-^ C F o < o <_) 1 m l_ 4-1 o c c a) <— < E vO o — .-^ — E • o en ^ co ^-" - OJ C 4J > - c — d) 4-J A =3 ro -o — — CO 4- 3 co c E < -H 3 < in 4-1 < — » c en o ^ E > 0) CO Q. 00 >- < y- — o o 2 o CM CN LA — 00 CM PA-^-^J'-^'COCN-J" (Ti^OO O CA PAPACNCNCNCNCNCNCNN^)LA-d"PAPAPAPAPA LA la la I — i^ rv <\j j- — vO CO-J-vOOOO-J-vjOvOlA 00 O N- (N IA4 ■JJ' cm la vO in ca ~ MinN LA O CN O O LAN N. i_A CN (TlNNOvC - PA CO ^O IN J- CO LA CN CA CA PA IN c\j LArAl — — CO CO~ rN pa — CN CA CA CT\ 00 — -3" O ^O PA CA LA CN CN — MM — — — LArocMCNMr^ro — CN— OOlALA— CNLA rA — PA CA CN O — CA 00 O _J -t — LAJ" CA LA In in in oo ■ — rA pa pa J- J" -4" -3" -3" O vO -J- o o o o o o N. _3" — CO LA CN — rA LA v£) 00 O oo vo-j n o m — CN PA J" -3" LA vO O O CA CA ^O vjO ■ — PA CN IN |_A CN LA v£> IN LA co — CM PA-3" LA vO A- 00 00 3 en E CM 0O < CM LA PA LA CA LA IN ~- LA CM CA -J" CO -3" — O PA — — CN CN PA -J" LA LA LA0O C\ 4"\0 N -t J - CN VO LA J" LA INCO PA O IN -J" OOOOOOOpA PAvOCAcNLAOO — O vO cm oo la — r — d"vO 0O N LA-J rA— OpA ■ — CM PA -J - LA\D >X) IN PA CM PA -3" LA vO FN IN »— O 00 LA rg \D lala^ rN CM — _ — A- CA CM — O O 00 PA — 0O vO PA J" 00 -3" LA 00 CM PA-Cf v£> IN CA — vO CM PA CA CA ooo LaNvo I s - PA ■ — PA LA ■ — CM CM — — — — CM LA PA LA CM O J" LA 00 — LA 00 PA — — — CM LA 00 CM IN 00 ^1" LA CM PA PA CM LA O O CM PA O O O O O — PA \£> CA CM LAN v£) (MOO LA — LA O — — CM PA 00 — CM PA -3" LA LA O LA — CM PA -J" LA LA LA -3" PA PA PA PA — -J - MD 0O CA CA LA rN CM vO PA CM — CM — 0O CA 00 PA IN O PA-3" — — CM CM CM PA 00 PA CM CM — CA LA CM LA J" IN CM 00 — CO IN O 0Q J" -J N (A- IN pa — CACO -3- CA O O vO LA 00 — PA-3" -3" LA LA IN ^o CO 00 CA\£> a~\ — ca \o oo cm o o CM -3" CM o o o o o rN PA vO CA CM LA CM — CM CALAvO-J PA v£> CA CM LA — — CM PA LA vO I — J" CM — CM PA -4" LA LA 0) — 3 en a. E O CM • — PA O ■ — OO LA 34 C CO CO tD (A C E 3 o O ■Q 01 4-1 03 3 03 i/> 00 CO < o in < co CD < cn, > ; < • o o CA-d s- O CO w O' O o cr\ c l/l 4-> o c c E - <_) u Q. c h- 1 1_ O u- O \D in • — • X) 03 — *J O < o <_> o c C 0) -h E 00 OO CT\rv^oO cACO LA ^O 4" N ro(T»4- O (N rv CM -d" IA LA r^ (Tl— — — -d" CA-d" LA O MO OO — roiAj- LT\N- JoOOvD4'vD — la CM — — — — CN vO o I — ^-v ■— E o cn 4-J co *^-^ 3 • l) c 4-» > •— c .— in 4-J la 3 m C CA < — 3 CO u- 3 O QQ c E b < 1—1 in 13 < — i_ > 0) LA CA CD CO O- oo >» < h- — O O 2 o CNi CM Csi OvOCMCOOOCAOO co cm CM ■ — — ■ — N o — -d" — — — cn cn m co d oo cn rs m o^ o oo SO rAIAIAdd LA (N O sO ■d- cn OOOOOOOsO rAvO 0^(N Ln 00 — G\ v£> cm co cn — is .3- cn oo is cn-d m — OJ- — CN m -d CA \£> v£> -d — CN oA-d LA^D IS IS 3 O- CN O CA E 00 < sO CO CN CN -d" VO NOAfM rAd vO IS-0O LAvO CO -d 00 — CA CSI CA SO IS fs cn ca — ■ — \£> — O is — 00 vD -d CN 0O — CM — — — is — O v^OO N OvD — CM CN — O v£> -d CA vO CM -d is LA O is O CA O O O O — rA sO CA CM is MD CM CO CA O O — — CM LA — CM CA -d" rs rs - CM rAdd — CO CA O CA — O vO is CO -d" oa CN CM CM LA LA VsO CA vO — LA \£> is o J- is O CA CM LA IS O -d IS CA O — IS oA — -d — O CA -d 0A CA CA 00 CA CM CM -d CN sO cm is rs o >s> o <|< E on on C - r— O O "v. c - oi O E o — ■ a. c E L. O - on o — < \ l/1 *-> - on X) i < v ' , ^ c . — "v. c on o E >_> — ' * < r- co CO < E on cr < o • o UJ — • \ QQ O" 0J E * — — on h- O est O O J" 00 i l O i i 1 o On o en o an CM r-. — LA i l vD i 1 CO CO CO o O vO LA LA o vO o CM LA CA O CTt 0) a. E 03 L0 T3 O QJ "O O D- O 1/1 "D O LA o..- 03 Q. 1/1 10 ■o (U d) Q. — E O 03 Q. L0 (/I O CM CA o CM CA o CM cn CA O CO O LA CM O CA O O . o -3" CM LA CM CA LA CA CA 0"\ O LA o LA vO O O LA o O o o o O o O o o o O o 00 o o o o LA o o o o LA o o o LA CM o o o LA CM O O LA CM cn o o LA CM CA o O O CA O o o o CA o o o LA CO o o LA CO O o CM LA o o CM -3- LA I"*. LA CO O o vO CA o o o CA o o CM o vO o LA CM o J- o CA o vO vO LA LA vO o CM 00 CT\ ■J" CA LA LA vO CA CM O CA CA CM CA CM J" CM 00 u-\ O CA LA O LA CM LA vO o CA LA O 1-^ LA CM LA \0 O CA LA o LA CM M3 LA vO 0) L. CJ 1_ (0 a> a; L. 0) O <_) l_> <_> C_) C_) <_> O O <_> rA O ca rA o vO vO O O Cxi O CM CM r-- O -3" O o CO VO O CM O O O o - ai i uoiusg 3} ! 1 II Ae 13 ei j 03d 38 c o o ■u o a NO L. o (A < a. < o o TJ in c (0 Ul 00 o c o • _ J- ih c >v o en 2. o • 3 < TJ 0) m 0£ o C o o a> c> • — en 4-J TJ Q. +j I. c o < O u ■M X d) Q (1) -C c o •fcj 3 J3 l_ 4J (/> o (/I CO < w 3 cn 6m 'S8V l p 3°± 49 E CD *-> (/> -o 3 "D > < a) in O (/) O 00 < a) 50 Metrecal System : The ABS distribution in the three phases of the activated sludge system which was fed Metrecal as substrate is shown in Figure 16. After repeated experimentation, it was noticed that even at the start of the experiment there was always about one-third of the ABS unaccounted for, and there was hardly any foam in the beginning even though the ABS concen- tration of the system was about 11.9 mg/1 . The foaming usually started after 35 about two hours aeration. This discrepancy was finally traced by an ABS tagged experiment and was found to be due to interaction or complexing of the ABS with some ingredient of Metrecal which allowed lower quantity to remain in the liquid phase and also it inhibited foaming. The appearance of foam after a period of time was due to the b iodegradat ion of the complexing compound in Metrecal, releasing ABS to liquid phase. Figure 16 shows that ABS in the liquid phase remained constant for about four hours before decreasing logarithmically. The ABS in the solid phase also remained practically constant for a while before decreasing. The solids data is also misleading because Metrecal itself is colloidal and about 35 per cent of its COD is retained on the membrane filter. Maltose Sludge with Dextrose Substrate : The purpose of this experi- ment was to see whether the ABS removal would be different if nonaccl imated sludge was used in the activated sludge system. However, it must be remembered that dextrose is a part of the maltose molecule and hydrolysis of the glucosidic bonds of maltose gives dextrose, so it was not a severe case of nonaccl imat ion . Figure 17 shows the ABS distribution in the activated sludge unit using maltose sludge and dextrose as substrate. The system behaved very similar to the one which was referred to as maltose system earlier. The COD removal had a some- what different kinetics than that of the maltose system. 51 [/6lu 'spi[OS aupjqiuan 'lu E 4) 4-> ft to -o < (0 u a; 3 jO l_ CM OO -3" O 6iu 'sav 52 /6iu 'sp|jos auejqiusw o o vO o o o o O o o o o CO -O 3 to 0) o X O E 0) ♦J >> co D 4-1 • 4-1 § < »- a> !/> O c o ■M 3 O CO CO < 6uj *sav 53 IV-3 • D i scuss ion Table 13 gives the total ABS removal per cent attributed to degra- dation of the four systems, and also the apparent per cent removal calculated Dn the basis of liquid phase ABS concentration alone. The per cent removal for the Metrecal system in the activated sludge unit after 2k hours aeration vas very high. This was also evident if only the liquid phase samples were analysed for ABS. The per cent removal of ABS in the dextrose, maltose and the nonaccl imated maltose sludge with dextrose substrate system was lower than the Metrecal system and was around 62 to 75 per cent, although the liquid samples removal was up to 84 to 98.5 per cent. This showed why it was necessary to evaluate the total ABS removal in any system; otherwise quite often liquid samples would give higher apparent removals. The per cent removals, except for the Metrecal system, were of the same order of magnitude obtained by Sweeny and Foote (5) in a continuously operated activated sludge unit with sewage feed, but were higher than that obtained by McGauhey and Klein (28) in activated sludge plants. This can be explained as follows: the recycling of enriched and col- lapsed foam back to the liquid phase allowed longer contact of ABS with the sludge particles. The very high ABS removals obtained for Metrecal system support our findings in Section V that complex substrate (bactopeptone) systems give much higher ABS removal in aerobic biological systems. This may be due to the presence of preformed cofactors in the complex substrate which allows an ABS degrading microbial culture to grow. The amount of ABS associated with the bacterial cells is shown in Table ]k. The ABS fraction associated with the cells is much higher than those r eported by Sweeny and Foote (5). The maximum of 20.3 per cent of total ABS was found to be associated on the cells for the system in which the maltose- 5h 4-> ; c •— CO CD D CO 1_ > < ID O Q. E 14- Q. (U o < CD c o 4-> D T3 < D l_ cn CD Q TJ O CO M- i_ \. CO O CD en < X) Q- E r— c C fO LU O 4-J o o 4-i 4-> h- fD fD l_ CD < E E T3 4-J o fD 1- CD E — E fD 3 4-J . — O O CM cn r-- CPi LA O CTi O r-- o LA CO CSJ CM CM O OA -CT oo CM CO CM co <7\ CA OA o CM o OA -cr r-- CM CM CM O OA O CTi -J- CTi CM OA o o co o LA LA vO CT\ CM CTi J" LA CO 0A cn CM CTi CO oo o CM CM O LA O CM CM O OA C =) a; ~o j-j 4-1 cn a; .— 4-J o X> M- c •— c 3 • E => c ZD — (D 4-J a) • — O in in ~ O in U IS) +J CO L. O 0) O X 4-J 4-J 1_ 4-J 0) X ■ — 4-J — Q (U (D CD CD Q s: s: S c o CD in fO x: Q. cr co co < CD x: cn c "O in c O o 55 Table 14. ABS Adsorbed on the Microbial Cells in the Various Activated Sludge Systems System Maximum ABS Associated Average ABS Associated Total ABS Fed with Solid Phase with Solid Phase % mq % mg mg extrose Unit altose Unit etrecal Unit altose Sludge Destrose-Fed Unit 22.2 22.2 kk.k 22.2 3-3 4.1 6.1 4.5 15.0 18.5 13-8 20.3 1.5 2.8 4.0 3.6 7.0 12.6 9-0 16.2 56 Jeveloped sludge was fed dextrose. The minimum of 15 per cent was encountered in the dextrose system. These results show that quite substantial amounts of \BS could be adsorbed by the activated sludges depending on the type of culture An attempt was made to determine if the solid phase adsorption of X \BS followed the Freundlich type adsorption isotherm expressed as loq — = r => m oq a + — loq C where 3 n 3 X — = amount of ABS adsorbed per gram of sludge C = concentration of ABS in liquid phase a = constant n = constant r he log-log plot of X/m and equilibrium concentration is plotted in Figure 18 : or the dextrose, maltose and Metrecal systems. The values of the constants 'a ind 'n 1 for the Freundlich isotherm are reported in Table 15- Table 15: Freundlich Isotherm Constants, 'a' and 'n' for ABS Adsorbed Cel 1 s System a_ n Dextrose 0.55 0.91 Maltose 0.86 2.86 Metrecal 0.1 0.75 As has been mentioned in Section III-4, the value of "a 1 is a good neasure of potential capacity of surfaces for adsorption. The maltose sludge iad the highest capacity by this criterion. The scatter of points in Figure 18 suggested that true Freundlich type isotherm was not obtained. This may have been because at any single time equilibrium conditions were not attained. ABS degradation >r uptake at the surface of the cell perhaps changed this equilibrium from time to 57 10.0 5.0 4.0 3.0 2.0 1.0 0.5 0.4 0.3 0.2 0.1 1 1 I Mill 1 — I — \—r Dextrose Me,trecal System Ma 1 tos System # Dextrose System A Maltose System ■ Metrecal System J L_Jl 0.2 0.4 1 2 3 4 56 7 8910 20 30 40 60 ABS Concentration in Liquid Phase, mg/1 Figure 18. Freundlich Isotherm for the ABS Adsorption on Cells in the Activated Sludge Systems 58 time. Further the foaming of the liquid under aeration removed ABS from the liquid phase and changed the equilibrium. The recycling of collapsed foam also changed the equilibrium. The amount of foam at any particular moment would be governed by the ABS in the other two phases too. So actually there .vould be simultaneous equilibria between the liquid and the solid phase ABS, and also between the ABS in the foam and the liquid phase. Figure 19 relates the ABS in the foam phase and the liquid phase. There was an increase in the \&S in the foam phase as the ABS in the liquid phase was increased. But after an optimum liquid ABS concentration where the ABS in the foam was maximum, there was a decrease in the amount of ABS in the foam. This was evident in all the three systems using dextrose and maltose. In the Metrecal system, no points at higher ABS concentrations were available because of the lack of foam in the system due to interaction or complexing of ABS and Metrecal substrate ingredient. The two maltose systems were very similar to each other regarding the ABS distribution in the foam and the liquid phase. 59 1 E 1 a) — 4J • co +j t/> >> X t/> >» co V o to CO a) 1 •"" IT) o> 03 03 O m w O u o o 0) 4-> 4-> 4-1 L. X — •— 4-» a) 03 03 03 o X s: £ CO vD rsi en E a> to 03 JZ a. E tt) 4-1 (A CO 03 cn -o 3 CO ■a 03 4-> 03 > a < 03 l/> 03 x: a_ E 03 O -o T3 — c 3 03 _ ... -u _J — 3 c cr co vX» CO CO < cn! 0) 4-> 3 a CO QQ < 3 CT> CM asecjd iueoj uj S9V 60 V. TERTIARY TREATMENT OF ACTIVATED SLUDGE PLANT EFFLUENT FOR ABS AND PHOSPHATE REMOVAL BY SAND FILTRATION This study was initiated to investigate the use of intermittent sand filtration as a means of tertiary treatment of sewage plant effluent containing ABS, phosphates and other refractory materials. Application of sewage plant effluent as a source of ground water recharge has been used at several places like Hyperian, Whittier Narrows and Los Angeles, California. Robeck, et_ aj_. (16) used intermittent dosing on sand lysimeters as a secondary treatment process for septic tank effluent and obtained a high degree of ABS degradation after a period of acclimation, or "ripening." McKee and McMichael ( 1 9) investigated the effectiveness of intermittent soil percolation fields as a tertiary treat- ment at the Whittier Narrows water reclamation plant in California. After proper ripening of the infiltration systems, they obtained ABS removals and as mentioned earlier, attributed it mostly to b iodegrada t ion and adsorption. Even our earlier study with unsaturated intermittent sand column indicated significant ABS adsorption and practically no degradation. V-l . Procedure Five sand filters were made of 4-inch diameter plexiglass tubes sealed at one end. A drain for effluent was installed at the bottom and air could be admitted through another part if necessary in case of anaerobic conditions. Figure 20 shows the details of the column feeding arrangement. The sand used was filter sand from Muscatine, Iowa, having an effective size of 0.29 and uniformity coefficient of 1.3. The depth of the sand column was three feet. The other details of the column packing are given in Table 16. The sixth filter was constructed of £-inch pea gravel instead of sand. The 61 Open to Air Syphon A (9 Screw Clamp Feed Bottle Dose Cylinder Syphon B Effluent Collector Figure 20. Line Diagram of Sand Column Table 16. Column Packing Data for Tertiary Treatment 62 Column Med i urn Med i urn We i ght Permeabi 1 "ty No. Type qms . qa 1 /ft/day Porosi ty 1 Sand 12,150 2,380 0.425 2 Sand 12,150 2,570 0.467 3 Sand 12, 120 2,370 0.441 4 Sand 12,150 3,370 0.498 5 Sand 12,150 2,540 0.511 6 Grave 1 13,750 6,300 0.421 Uniformity coefficient of sands was 1.3 Effective size of sands was 0.29 mm. Gravel size ranged from 1/4" to 3/8". 63 reason for using such a large particle size was to ascertain the refractory removal characteristics of the gravel filter under heavy loading conditions (especially high hydraulic loads) without any clogging problem as encountered in the sand filtration where ponding and clogging occurs in case of heavy appl icat ions . The sand filters were initially seeded with a synthetic sewage con- taining 10 per cent settled sewage, dextrose (250 mg/l), NH, C 1 and phosphate buffer which allowed a heterogeneous microbial population to grow. After four days of seeding, good biological activity was evident from the COD removal data. The final effluent from the local Champa i gn-Urbana activated sludge plant was feci to these bio logi ca 1 ly active columns every day. The character of the feed is given in Table 17- The feeding schedule for each column is presented in Table 18. The dosing period was adjusted with the help of pinch clamp control of the inflow to the siphon. Frequent checking and control allowed the required dose intervals. After two months of operation, the feeding schedule of some of the columns were changed as shown by the period B in Table 18. Daily samples of influent were collected prior to application to the columns. Effluent of the columns was sampled soon after feeding. For column 3, in which the flow was very low, the daily composite sample was used. It was intended initially to determine the following tests on these samples: ABS, total phosphates, nitrogen (nitrate, nitrite, ammonia and organic), BOD, COD, pH , suspended solids, and total plate counts. In this report only ABS, phosphate and COD data are included because the other data were erratic and there were too few complete data. The analytical technique used for ABS was the methylene blue test as outlined in Standard Methods , 11th edition (\k) . The letermination of phosphate was made by the procedure outlined by the Association 6k Table 17- Champa i gn-Urbana Activated Sludge Plant Effluent Characteristics Summer 1 963 Average BOD, mg/1 20 Average COD, mg/1 70 Average Total Suspended Solids, mg/1 16 Average Volatile Suspended Solids, mg/1 11 pH 7-0 Nitrogen - NH , mg/1 as N 2.4 Nitrogen - Organic, mg/1 as N 6.5 Nitrogen - Total, mg/1 as N 8.9 Nitrogen - NO , mg/1 as N 2.5 Nitrogen - NO mg/1 as N 0.5 Total Viable Counts 350,000 Average ABS, mg/1 2.5 Average Total Phosphate, mg/1 as P„0 kS cn c •— >. ■c . M LP* ig O si CM 0-0- t/> §. CL C" C >- — ID ■Q XI - "D ID ID X) O ^ _JfM E IS) \ 00 E < CD 1) U c - 3 ID o--o V "o. uO -o t 0) •— 0) 4-1 u. 1) 4) u. U 4J ro >. CC ID X) XI V. 0) E u u_ 2 O u. >• ID — XI ID — 4J ^ t- c E 3 O — z o <-J — < XI o o r-- ro -3- vD LT\ CO 1 — .* J- ro eg ^~ ro LA , , , cn cn CM ro ro ro CM ro ro -a- vO CM CM ro LA -d- CO O ro ^O vO cn v£> ro CO ro ro vO ro o o o LTV CO o o -a- CO CM O o o o o CM o -a- o o ro o" o o O o O O O o O o O o O o O -3- O vO «N o LA CO _ CO CM -d" CO CM ro o O ro — CM ro cn LA ro O LA CM LA CM ro O ro O LA CM LA CM ro O ro O LA CM LA CM CO -4- CO -a- o -a- o -a- ro o CM O VO cn o cn o o o o o v£> 65 < CO X) XJ o o u i_ cn u s. -a c CO -a- o o. CM X +- v£> o ro\ vo -a- cn v» — c CO s •— •o. — 4-i cn — in o o t/i 4-> 4-> c o ro ro o vO vO \ *o. X) ro cn V *o. \ V r^ cn <4- 0) -C ■*-> c >- 0) Q_ 66 of American Soap and Glycerine Producers (AASGP) (29) . It consisted of forming phosphomo lybda te with the addition of ammonium molybdate to sample containing orthophosphate . The phosphomo 1 ybda te was extracted by benzene- isobutanol solvent and reduced subsequently with stannous chloride to give a blue color, which was read at 630 mu. wave length in a spectrophotometer. Condensed phosphates were determined by boiling the samples in dilute sulfuric acid which converted it to orthophosphate and the procedure for orthophosphate was then repeated. The difference between the orthophosphates in the acidified boiled samples and the sample without this treatment was taken to be the con- densed phosphate. The organic phosphates were converted to orthophosphates by wet ashing procedure and the method for determining orthophosphate then followed with the wet ashed sample. This gave the total phosphate. The organic phosphate was determined by the difference between this value and the total condensed plus orthophosphate. V-2. ABS Remova 1 V-2,1. Resu 1 ts : The average ABS removal for each of the two periods of different feeding schedule are reported for all the six columns in Table 19- The standard deviations are also reported. It will be noticed that there was significant deviation in the data. The COD removals are also presented in Table 19 which is quite closely related to the ABS removal data. Figure 21 shows the relationship between the COD and ABS average removal percentage of the six columns. There is almost a linear relationship between these two parameters, except for column 2 in the second period when synthetic feed was applied. The average ABS concentration of the influent was 2.5 mg/1, and the average BOD was 20 mg/1 and the average COD was 70 mg/1 over the entire period The effect of hydraulic loading applied to the sand filters on the ABS and COD 67 C *-> ■ - c c — E ^*- U <4- — UJ o C — n> 0) — > Q. L. Q) (J LTI X) XI u c — 03 CO O g •u > c 3 £ ID ID o L. o H . ■a L. c TJ 10 •— 4-1 t/J L. C2 a < l- a\ J3 \0 c E D o X) c OJ x> c OJ CO XI c CO X c en O (0 E i_ OJ 1) cc > < cn LA en OA -3" LA CA CM CM CM O > &s CO Q <4- X o 03 s_ C > 03 o O X E c 4-J 03 OJ 03 a: CM O CM CA CM OO CM VO CA 00 CM J" LA en J- o en en en CM Q O C_> ■^ O o^ ' 03 03 > CD O 03 E !_ OJ OJ cc > < CM vO -J" LA vO vO CO -4- OA O ■J- CM CM CM CM ■£ o CM > ss OJ o — X) 0J i- c > 03 O O xi — E C 4-1 OJ 03 03 CC 4-> co < CO CO DC UJ Z O > < - 1 ooo a: in S o > < - 1 OO vO CA "v. v^3 -J- S i— 00 *v» en — o O 4-J 4-> OO OA vD vO \ "V. CO en \ s r-> en < CO XI X) o o 1_ !_ OJ OJ a. a. 68 c E o c TJ to 0) q: o o o 0) .c c 0) CO < TO Q. E O o (N 3 cn o O o o o o o O CT\ oo r*. vO LA -3- ro CM 31133 jaj '[PAOUJay $g\/ a6ej9A\/ 69 removals are presented in Figure 22. The removal efficiency for ABS and COD decreased linearly as the hydraulic loading was increased. Column 2, which vas changed from feeding activated sludge plant effluent to a synthetic feed (bactopeptone , NahLPO, and "Tide" detergent) showed remarkable increase in \BS and COD removals after the change was made, as is evident from Table 19 and also Figure 22. In column 5 the feed rate was doubled in the second period, although the feed sequence remained the same, four times a day. The ABS r emova 1 in the column fell to about two thirds of the previous value, although ~he COD removal decrease was only 20 per cent. In the pea gravel column, the feed sequence was changed from four times a day to twelve times daily, although the total amount fed daily was the same. This reduced the ABS removal capacity ;onside rably . However, in the sand column 3, which was also fed twelve times a day, the ABS and COD per cent removal was the highest of all the columns. Cumulative ABS removals were obtained for each column based on the average ABS removal per week for the entire period. Figures 23 and 2k present these cumulative removals for the six columns. Table 20 shows the cumulative ^BS removals for the six columns. It will be apparent that column 5 removed Tiaximum ABS over the entire period although column 3 had the best ABS removal fficiency as measured by the per cent removals. Column 2 in the second period :annot be compared with the other columns because the feed was synthetic instead of activated sludge plant effluent, although its efficiency of removal was the :est of the lot in that period. Prior to dismantling the columns, ABS was eluted with tap water in order to obtain an idea of the physical ly adsorbed ABS on the sand filter. : igure 25 shows the ABS eluted from the different columns and the amount of ABS eluted from the column are reported in Table 20. The amount of ABS eluted was 70 nj 03 > > 1 i 0) LL o CM •— •u c 0) E _c 3 •M i — c >» o 00 r*> CM c E 3 *— o o "O c (0 CO a; jt +j >» LTV -Q 1 o #— •— X o E 0) ■M c o c — o *— ■ 3 X » X 4-> o (I) LLl CM CM a> u 3 en o 00 o vO o o CM 31133 jsj 'teAouiay qqo pue S9V ©6ejaAv 71 12 15 18 i 21 Column No. 1 Increased Feed. Column No. 2 Feed Changed to Synthetic vFeed Column No. 3 15 18 Figure 23 6 9 12 Time, Weeks Cumulative ABS Removals in Columns 1, 2 and 3 21 800 12 72 15 18 21 600 Column No. 4 400 200 800 600 400 200 - 800 Column No. 5 Feed Doubled. Column No. 6 600 400 200 Feed Sequence Changed 9 12 Time, Weeks Figure 24. Cumulative ABS Removals In Columns 4, 5 and 6 21 73 Table 20. Cumulative ABS Removals and the Amount of ABS Eluted from the Columns Column No Cumulative ABS Removed mg Total ABS Eluted from the Column by Tap Water mg kkS 630 800 817 535 0.75 4.0 8.4 10.5 5.4 7*» o (A < eg O c o o • o m o CM CM 0) 1- &, 1/6uj '^uani^^a uj S9V i° uoj}ej}uaouoo , .' 75 of the same order of magnitude for all the columns except column 2, which eluted much less ABS than the others. This was the column which showed maximum per cent ABS removal but it had very little ABS which could be eluted by tap water. This elution experiment was extended in the case of column 5- After the elution activated sludge effluent was percolated through it again and the ABS removal evaluated immediately. There was a sudden increase in the ABS removal which fell off as days passed after elution. Another elution was made after eight days and again significant increase in the ABS removal was obtained on refeeding as shown in Figure 26. The per cent removal fell off to that before elution in a couple of days . The columns were dismantled after the experiments were over. The soil samples at successive depths were taken in order to determine the volatile solids, number of mi crorogani sms , moisture, etc. All columns were aerobic from inside and had a fresh soil smell even at the zone of saturation at the bottom. T able 21 gives the data on the variation of volatile solids, moisture and number of microorganisms with the depth of sand bed in the six columns. Figure 27 graphically illustrates these variations. An attempt was also made to determine the amount of ABS associated with the scrubbed cells from the sand and on sand itself at various depths for column 5- Table 22 shows the variation in the ABS desorbed from the sand at various depths in column 5- The total amount desorbed was very close to the value obtained earlier during elution experiment with tap water . V-2.2. D iscuss ion : The data of Table 19 show that intermittent feed, as in column 3, was more effective in removing the ABS and COD through the column as compared to the slug loading once a day as used in column 1. Column 3 was even better than column 2 which was dosed four times a day as compared to 76 L. V *■> (0 Q. Q) 4- < o 0> CO LT\ C E o o CO CO < Csl u }uaQ jaj 'leAomay $gy a6ejsA\/ 77 o oa r-. la LA ^o -J- en J- LA r- LA o CTv CM LA o CD E O !_ (U Q CA CM r-. vO LA C E D o CM oo LA CO LA CA CM PA CO LA O OA CM OA oo OA O OO oo CM CM oo If) ro — ^— O O 21 > ■u ■u !_ c c 0) CD CD 4-< O O ■M 03 u s_ SI 0) CD Q. Q. O^ LA <3A O LA CM 0O E CA ^O CTi 00 CM on LA CA O0 O CPi LA ■J" CA J" CM 00 -Ct" J" CA -J" O O^ CA CA CA OA 00 LA -J- O O 'o O^ VO O CM CA 00 O^v r-. o vO CA o vO CM CM 0O r-. CM CA 0O vO CM 0O en CM CM J- CA E ro u CD CD en !_ ■ — n .— s-d- 4-J ■M X S > L) E in ■— 4-J 4-J i_ k ._ ._ c c CD c CD CD 4-1 u- (D l/l <_) c_) 4-1 CO Ol L- 14- i_ L- 21 O O CD CD 0_ Q_ ■z. 1/1 x> CM O i/i vO CD n 4-1 ■ — ro CO > T3 CD -C 1_ CD 14- -C c >« CD — -C CD 3 > X) 1/1 CD 1/1 c (D • — O X 1 — CD to CD > l/> CO ro cn 2 XI vO O jZ c 4-1 E CD D E 1 — O 1/1 O .,— -C C 4-1 >- — -Q u > ■O CD CD i_ C CD .— CD cu 4-J _c -Q h- O 78 --, ft X) 09 O W c a rd •H V +J o rd o o\-> 0> 3 +-> to •H o T3 C id CO o £ to I o to •H rH O co o •H 4-> •d H O > o ® to 3 •H O O x» c CO •H w c Q rd •H £. o id PQ *a c id w T3 •H rH O CO a> H •H •p id o > fc. 3 +-» CO •H o o c o •H m id > Po- CM 0) 3 bC •H Cm (uio34oq uioaj iuo) uumxoo ut expaw jo qjdaQ 79 twelve times for column 3- Thus, it appeared that the frequency of loading was a factor which must be considered in the soil percolation system for tertiary treatment, McGauhey and Winneberger (30) studying the failure of septic tank percolation system, advocated the use of intermittent dosing in order to maintain optimum infiltration rates in the soil. Similar observations were also reported by Robeck, e_t_ a_l_. (31) who found intermittent dosing was necessary to keep the top active layer of soil system aerobic when organic waste was applied to it. They suggested three to six times a day feed conditions. Our f indings def i ni tely snow that twelve times a day feed sequence was better than four times in sand columns. We did not perform any intermediate dosing sequence between 12 and k times a day, but it is clear that small amounts fed at numerous times is better for ABS removal. The decrease in the ABS and COD removal with the increase of hydraulic loading as shown in Figure 22 was quite normal. As the loading rate increased, the ponding of waste at the top of the sand allowed a much faster flow rate through the column giving very little time of contact between the microbial cells associated with the sand. A slower rate of flow associated with lower hydraulic loading would allow much more time of contact between the cells and r efractory materials for adsorption and subsequent degradation. These removals have been calculated over a period of about nineteen weeks and throughout most of this time consistent ABS removals were obtained, so it could be deduced that the ABS initially adsorbed on the surface of the microbial cells was being degraded. The cumulative ABS removal curves show that initially there was good ABS removal, followed by a poor removal period after two to three weeks and again good removal later. In some columns there was poor removal after 10 weeks. This could be explained because after 10 weeks the 80 feeding schedule of columns 1, 5 and 6 were changed and there was also a change in feed substrate in case of column 2. Columns 3 and k were kept on the same feed throughout the period and the trend of ABS removal in column 3 was practically unchanged, but in column k there was a reduction of ABS removal after 10 weeks which was not accounted for. The trend of ABS removals for columns 2, k and 5 are similar to those obtained by Robeck, et_ aj_. (16) and also those obtained by McKee and McMichael (19) at Whittler Narrows waste water reclamation fields. However, the per cent removals were lower than reported by Robeck, et_ a_l_. (16). Two factors may be responsible for this lower ABS removal in our system. Firstly, 2 the organic loading in our case was much lower--6 g/m /day as compared to 16 to 2 $k g/m /day appl ied by Robeck, et_ aj_. (16) . Thi s would limit the growth of microorganisms in the filter to quite an extent. Secondly, the form of carbon in the effluent from an activated sludge plant would be quite different from that obtained from a septic tank. The materials in the effluent of the activated sludge plant are not easily degradable, otherwise they wouldn't be there. On the contrary, the effluent from the septic tank usually has much higher BOD and contains more easily degradable organic matter as compared to the activated sludge plant effluent. The ABS elution from the columns show the importance of adsorption in such soil systems. Elution experiments in column 5 were very significant. There was an immediate rise of ABS removal after elution which clearly showed that the ABS eluted released the adsorption sites on the sand or microbial cells for further adsorption. But soon the adsorption sites were again covered and the ABS removal fell. Adsorption was not the only mechanism of ABS removal in the columns, since itwas evident that no breakthrough was obtained even after 19 weeks of operation. Further the sand and microorganisms obtained after the experiment from column 5 released about the same quantity of ABS as released by the tap water elution and corresponded to about 1 u.g/g of soil. If adsorption was solely responsible for ABS removal of 81 317 mg in column 5 over the entire period the amount of ABS adsorbed per gram of sand would be 67 micrograms. This is much higher than the reported values of about 1 to 10 micrograms per gram of soil for ABS adsorption on sandy soils. The microorganisms in the sand were much lower than the open column experiment reported in Section II and so was the concentration of volatile solids. Thus we could not explain this high ABS removal in this column on the basis of ABS adsorption on biological slime. Therefore, the mechanism of ABS removal in such soil systems appears to be adsorption on sand and microorganism surface followed by biodegrada t ion . The performance of column 6, the gravel column, was much poorer than the sand columns as was expected since there was much less surface on which the microorganisms could grow and also the residence time was much smaller in this column because of the high permeability of the column which allowed less contact of waste to the microorganisms growing on the gravel . The change in the feed sequence from four times a day to twelve times reduced the ABS and COD removal efficiency. This was contrary to our finding with the sand columns. This could be explained that greater permeability allowed microorganisms to slough off from the gravel because of the more numerous feedings. Column 2 was initially fed activated sludge plant effluent at 2.5 1/day at four doses daily); the performance was fairly good as indicated in Table 19- After two months operation the feed was changed to a synthetic one containing soluble carbon source as mentioned earlier in Section V-l . The performance of the column was markedly improved, the ABS removal went up at times to 95 per cent although the average was about 76.9 per cent. This high removal was quite consistent and was perhaps due to better selection of microorganisms capable of ABS degradation with the complex substrate. The COD removal data of this column 82 was also extremely good, indicating good biological activity. The high ABS removal with complex substrate in an activated sludge system was reported in Section IV-2. The data of Table 21 show that the volatile solids were quite constant in all the sand columns, about 0.7 to 0.8 per cent. However, there was some variation of volatile solids content within the column depth. Usually there was higher volatile matter at the top than at the lower parts of the column. The amount of microorganisms were also greater at the top of the columns 1, 2, h and 6, but there was no general trend as to the distribution of the microorganisms in the column with respect to depth. The correlation between the number of microorganisms and the volatile solids was also not evident. The amount of ABS desorbed from the sand in column 5 at different depths as indicated in Table 22, agreed well with the amount of volatile solids at those depths. The per cent volatile matter at various depths for column 6 was very high. This was thought to be possibly due to the calcination of the carbonate fraction of the gravel itself at 600°C giving a false increase in the volatile matter. V-3. Phosphate Remova 1 (32) V-3.1. Resul ts : Table 23 reports the average phosphate removal over the entire period. The or thophospha te removals during the first period (Period A) were higher (from 11.6 to 32.2 per cent) and more consistent than that in the second period. Often in the second period (Period B) the orthophospha tes of the effluent were higher than the influent due to conversion of condensed phosphates. T he amount of condensed phosphate in the feed to the columns in both periods was relatively small, around 1 to 2 mg/1. The removal of condensed phosphate was quite high in both periods. The organic phosphates in the feed were also quite 83 Table 22. ABS Desorbed from Sand in Column 5 Sample Height ABS Recovered per Amount of Sand Total ABS No. from Bottom gm of Dry Sand in the Zone Recovered cm lag gm mg 1 92 1.73 1584 2.7 2 68 0.95 3498 3-3 3 41 0.64 3630 2.3 4 11 0.52 3432 1.8 Average . 96 ug/gm Total 12,144 gm 10.1 mg 8k CO Z3 J o o Q 2 < >~ CO. J < > O 2: w < X Cm CO o n cu o < < Q 2 O M H < M > u Q Q OS < Q H CO o > < (0 co CM 2 C T) E 3 -H H U 0) O Cm co r-- CM H CO co 00 r-^ 00 ID CO CD cn cn • • • • © • • _t m CN r-\ CM cn 00 d- CO s-X v-< A d- N— ' v-* CO CO CO cn (0 00 O _t • * • en H CM CO CO d- CN CM CJ> CO CO in CO m r- 00 CO CO CN CO CO O rH 1 O • • • • • • • m it rH rH ^1- r-~ in in d- CO CO d- co m CM O in r>» in 00 CO .* rH CO CO in in 00 CM cn m cm H -H -H CN H rH CO t> cn CM CO -H .H CM CO CO -H X 00 t"» cn CN •-\ CO rH J- cn in H CM 00 CO CO in < 1 O • • • • • m O «H •H rH rH CM t-*- d- d- 3- m .3- d- r> CO t> CO CN cO in en cn CO O O r^ in f- CO in 00 •H r-» in CT> rH H CO rH rH CO m cn CO -H r> a> .h m CD CN CO CO CO 1 • • • • • * • d- r-l O rH CM O •H m CO m in d- in m d- 10 in CD 00 rH CO CO CN CO CO cn cn co rH CO CO CO CO 3- • • • • • t> J- .H t^ r-{ H m cn in rH CN -H CO _t it CM rH CO CT> O CO CO CM CM :* in in t> cn 00 3- cn CO CO J- O cn 1 • • • :* in •-{ m CD in CO X in m _r CO CN cn 3- cn CO CO cn in CM in 00 00 cn t^ X cn CN • • • « • • e 10 t> CN r- rH CO 00 CO in CN H CO cO in CM H CO CO H O -i- rH 00 CO CM CO CO _t in r> d- rH CM J" 1 O • • • O r-» O O CO CN f-\ in O in CD CO in CO 3- cn in t> iH .* CO co m m cm CN CO CO _t r~ CO m cn CM C*» e » • CD CD 00 O O CO CO cn cn rH CN H CM CO CO CN H CO co t> m in CM m CO H rH CO CO rH 00 r» •-i CD 1 O • in rH .H CM rH CO r» •3- CO -f d- CO ^~ 10 O CD c^ m CO CO 00 in CO iH cn cn cn f» CO cn r^ CN • • « • • • ■ 00 st- C-* » s. bO <#> CO \ bO C»P 4J bOT) E H tO co E U * 4-» rH 1 42 bo « <0 • C CO c x: bo • t0 • c to •H JT, bO • (0 C fO jC bO * to c to cu to • *d to CO > CO CX (0 • 'O to CO > c a to • X> to CO > nam • ti 10 CO > £ M f( U C 'H p co c to t> O O T3 W fc O C «H CJ O to to U V c •H O O nj w u c •H O O U E c 0) c ro > U E bO CO c rd > U E ■P O CO c to > U E fc £ > OP Jl 0) CO O JZ > O P CO CO CO fc ,c > P CO 9) CO O jC > O P CO CO CO O Cm < O CO Q CL, C< a, < O CO O Cm Cm O Cm < CO Q Cm Cm tr- Cm < O CO Q Cm C4 T3 co CO Cm O •H ■P CO x: •p c CO 85 ow averaging about 2 mg/1. The rate of reduction of organic phosphates was igher in the second period in most columns than in the first period. The verage per cent removal of the total phosphate was lower in the second period s compared to the first. This decrease of the total phosphate removal for ach column is indicated in Figure 28. The increase in the feeding rate (as bs P O c /acre) decreased the average total phosphate removal. This was similar o that obtained in ABS removal data presented earlier. In the case of phos- hate removal too, column 3 performed most efficiently. The cumulative total phosphate removals are reported in Table 2k ased on the average removal per week for each of the columns. The cumulative hosphate removal for column 5 was highest like the ABS removals reported arlier. From the plot of cumulative removal with time for all the columns Figures 29 to 3^), it was evident that in columns 2, 3 and k the initial igher removal was succeeded by continued lower removal. This was indicative f predominance of adsorption initially and assimilation later by the micro- rganisms, although both adsorption and assimilation may be present to some xtent in both the phases. In Figures 30, 31 and 32 the probable amount of otal phosphate removed by adsorption and by assimilation are marked. This -ocedure could not be well applied to other columns 1, 5 and 6 because the perating conditions changed during the second period. The changed carbon ource in column 2 did not seem to upset the balance in the total phosphate amova 1 behavior. The elution experiments described in Section V-2.1 were also done the total phosphates on the samples eluted out of the columns. Figure 35 r esents the elution curves for total phosphate from the five columns. All he sand columns gave very similar results, but the gravel column 6 gave much ' 86 35 30 d£ W 0) TO J= O. W O TO O TO > i 0) 05 0) hO TO +J C o> u 5- 0) a, < 25 - 20 15 - 10 (1. JT, I 1 First Period Second Period T35 nr Column Number TT T6) Figure 28. Comparison of Total Phosphate Removal Between First and Second Period 87 Table 2k. Total Phosphates Removed and Amount That Can Be Eluted (>lumn No. Total Phosphates Removed by Column mg P 2 o 5 Phosphates Eluted by Tap Water mg P 2 5 Phos Feed mg p 2 phate Load /day A B 109 613 109 102 109 123 17 1 * 196 261 588 435 490 3609 2582 3078 4351 7852 5313 88.8 66.8 95.5 85.1 22.5 / = Fi rst Period i = Second Per iod 88 t+000 3000 CN to E > E V w ■p «J jr D- (0 .c (X, +J o H 0) > •H 4-> (0 H 3 E 3 O 2000 1000 Feed Rate =2.5 t/day Feed Rate =12.5 t/day 8 10 12 Time (Weeks) 20 Figure 29. Cumulative Total Phosphate Removed by Column 1 89 1 1 1 1 I 1 1 1 i 3000 _ Feed Rate =2.5 i/day ^ •" s ^^- & *~ in O a *** e ^2?** CM a. bo e >-/ 0) > 2000 — E a> OS ir 0) •p a x: a (0 J Removed by Adsorption — *■ Om •H TJ +-> H £ 1000 — +J o e a) a. v, 0) m a w o OJ o H a> > H e 3 a 2000 1000 Feed Rate =2*5 i/day Removed by Assimilation 6 8 10 12 14 16 18 20 Time (Weeks) Figure 3 1 . Cumulative Total Phosphate Removal by Column 3 91 8 10 12 Time (Weeks) Figure 32. Cumulative Total Phosphate Removal by Column U 92 8000 i r 7000 6000 id o CM a. bC E Feed Rate = _ Feed Rate = 12 &/day 500( > o I H § 3000 2000 1000 — 8 10 12 Time (Weeks) 20 Figure 33. Cumulative Total Phosphate Removal by Column 5 93 6000 5000 m o CM a* bO E t3 uooo > o e o a: u <» 4-> •H CJ 3000 reed Rate = 10 i/day Feed Sequence Changed 2000 1000- 8 10 Time (Weeks) iV 14 16 is 20 Figure 3^. Cumulative Total PhosDhate Removal by Column 6 Sh CO o o 3 w LA u •H ( S 2 d TJ/^ui) ^usnTjjg "T uoT^eaauasuoo ajeiidsoqj 95 smaller quantity of phosphate. The quantity of total phosphate eluted from each column is presented in Table 2k. These values were calculated from the elution curves in Fi gure 35 • The elution experiment on columns k and 5 were extended. They were refed with activated sludge plant effluent after the tap water elution and the total phosphate removal calculated. There was immediate rise in the per cent removal of total phosphate as indicated in Table 25. Another elution followed ten days later on column 5; again there was immediate increase in removal of total phosphate. Figure 36 depicts this immediate increase in the total phos- phate removal after elution with tap water in column 5- These data are remarkably similar to that obtained for ABS elution experiments reported earlier. The gradual decrease in removal after elution with the passage of time was also evident here. V-3.2. D i scussion : The results obtained in this study have shown that a minor but significant amount of phosphate in all forms has been removed by the sand columns under study. Greater phosphate removals were observed in the early period, probably due to the physical adsorption on the sand particles rather than the biological uptake by the microorganism. Or thophosphates were removed more effectively in the first period than in the second period as shown in Table 23. The or thophospha te content of the effluent was in some cases in the second period higher than the influent. This increase was attributed to the decay of bacterial mass. In the second phase the microbial growth may have r eached its peak and dead cells reverted the organic phosphate in the protoplasm to orthophosphates . It was found that the concentration of condensed phosphate in the influent was quite low. In the activated sludge plant and also in the aqueous 96 Table 25- Phosphate Removal Before and After Elutlon Before Elution After Elution Phosphate Content Phosphate Content 0,umn Per Cent Per Cent No Influent Effluent Removal Influent Effluent Removal mg/1 mg/1 k 41.8 39.6 5.2 48.7 9-0 81.5 5 48.6 42.5 12.6 42.8 4.7 89.O 5""' 54.8 53-7 2. 1 51.0 6.0 88.2 Second Elution 97 IT) c E 3 H O O *H O > 3 O c o •H •fj 3 rH U u 3 be (° 5 ) xeAOuiay saieydsotij ^usoaaj 98 phase, the condensed phosphates were hydrolysed to orthophospha tes so there was not much left in the feed solution. Removal of condensed phosphates ranged from 22.3 to 67.3 per cent in the columns, indicating that the condensed phos- phates in the feed solution still continued their hydrolytic degradation while passing through the sand columns. The organic phosphate data showed the average removal varied from 23.3 to 68.8 per cent, although the data were not very consistent. To some extent organic phosphates represent microbial mass, so any decrease in the effluent may indicate removal of microorganisms in the filter and conversely any increase in the effluent over the influent may indicate exodus or sloughing of mi croorgan i sms from the filter. The rate of total phosphate removal decreased with time, especially in the first period. The removals started at the highest rate in the first week and then slowed down. Initially adsorption was predominant and its effect de- creased with time due to the saturation of the surface, while assimilation of the phosphates by microorganisms predominates thereafter when the population had built up to significant amount. The biological slime may adsorb the phos- phates too. As the microorganisms multiply, the adsorbed phosphates on the surface of the cells will be assimilated by the microorganisms and become a part of the protoplasm. The phosphate removal rate was less but more consistent in the second period than in the first. This was because the adsorption effect had almost reached its saturation at the end of the first period, and the microbial population had built up and reached a state of balance in the second period, so the phosphate removal in this period was mainly due to biological assimilation. The effectiveness of phosphate removal was found to be a function of feed rate. Further, intermittent feeding was more effective in phosphate "emoval than a slug loading. Considering the results of columns 1, 2 and 3, it 99 was clear that although the total daily feed to these three columns was the same during the first period, column 1 received a slug dose once a day and showed the poorest removal efficiency, column 2 was fed four times a day and indicated better removal, while column 3 was dosed twelve times a day and ap- peared to be the best. This relation between number of dose per day and removal of phosphate was observed also in the second period. The total phos- phate removal efficiency also decreased with the increase in the total hydraulic loading. The data appearing in columns 2, k and 5 and in Table 23 indicate this clearly. The gravel in column 6 was poor in removing phosphates as was also evident in the ABS removal experiment. The surface provided for adsorption and microorganism growth was much less in this column than the sand columns. The cumulative phosphate removal data in Figures 30, 31 and 32 for columns 2, 3 and k show the calculated amount of phosphate removed by adsorption and assimilation. It was found that the amount of phosphate removed by adsorption in columns2 and 3 were of the same order of magnitude, 1 850 and 1 900 mg of P ? respectively. These two columns were fed the same total amount of activated sludge plant effluent per day so the amount of phosphate adsorbed should be the same. However, the amount of phosphates removed by microbial assimilation was different, being only 732 mg of P~0 in column 2 and 1 1 78 mg of P 9 in column 3- This difference may be due to the different dosing periods for the two columns. Further, the carbon source in column 2 was changed during the second period which could have caused this discrepancy. The results of the elution experiment in- dicate that the phosphate retained in the column either by adsorption to the sand or to the microorganism surface could be washed out. The total amount of phosphate thus eluted was only 2 to 3 per cent of the total phosphate removed in the nineteen weeks and about 3-5 to 5 per cent of the phosphate removal attributed to adsorption 00 vas calculated from the cumulative phosphate removal curves, Figures 30, 31 and 32. The elution curves in Figure 35 show that the flattening of the curve occurred after three pore volumes of tap water had been applied, and it may require quite large quantities of tap water to completely e 1 u te the adsorbed phosphate. This may be the reason that we did not obtain complete elution of the adsorbed phosphates in inaccessible zones. The restoration in the capacity of phosphate removal after elution was quite interesting and supported our hypothesis that in the columns adsorption was playing a role in the removal of phosphates. The use of sand filter for tertiary treatment for phosphate removal could be effective if periodic elution of the bed was made with phosphate-free water in order to recharge the adsorption sites. The elution would be similar to the backwashing of the rapid gravity filters. The elution water containing high phosphates would still be a waste disposal problem, but the total volume would hopefully be reduced in this process. This small volume of water con- taining high phosphates could be held in an oxidation pond for algae culture for animal food or could be used as fertilizer around the area. VI. CONCLUSIONS 1. Biological slime in a biologically active sand column retains luite substantial amounts of ABS depending on the condition of the column. Jnsaturated flow with aerobic conditions enhances the retention as compared to anaerobic saturated flow conditions. No ABS degradations were obtained in short time experiments with unsaturated flow sand columns or in anaerobic saturated columns. Sterlization of the biologically active sand column by autoclaving reduced the ABS retention of the column to that of nonbio logica 1 ly active column. The retention of ABS in the columns was easily eluted by plain later containing no ABS. 2. ABS adsorption on the various soils studied showed that intensity f adsorption increased with the increase in the grain size. There was no major effect of mi nera logi ca 1 composition on the ABS adsorption on the soils tested. pH drop favored more retention of ABS on Ottawa sand. The ABS ad- sorption was proportional to the square root of the surface area measured by the glycerol method. This showed that although adsorption increased with the '^crease of surface area, it was relatively lower on materials with high specific surface when compared to materials like sand or sandstones which had low specific area. The adsorption of ABS on the soils tested followed Freundlich's 'sotherm and the "a 1 value of the Freundlich equation served as a good indication of the relative intensity of the adsorption by the soil for the different types f ABS used and the relative adsorptive capacity of the different soils for the ABS. Pure pentadecyl benzene sulfonate was adsorbed less than the pure dodecyl benzene sulfonate by all the soils tested. However, the C - 1 5 blend ABS was adsorbed more than the C-12 blend ABS. Pure dodecyl benzene sulfonate was ad- sorbed more than any of the ABS's tested on all the tested soils. C - 1 5 blend ABS cie 102 s adsorbed more than the pure pentadecyl benzene sulfonate. The amount of trface area covered by ABS in the batch experiments with clayey soil was very i sign! f icant , 0.2 to 0.^+ per cent for bentonite. The amount of ABS covered in le case of sandstones ranged from 31 to 71 per cent in the case of Mi ss i ss i ppian- sandstone to 9-8 to k$ per cent in the case of glauconitic sandstone. There vs indication in the case of Ottawa sand of multilayer ABS adsorption. ABS sorption reduced the base exchange capacity of the clayey soils. The reduction vs directly proportional to the amount of ABS adsorption in case of soil con- lining high montmor i 1 loni te clay mineral. This reduction in case of clays with iw exchange capacity and without latticed structure remained constant with gher ABS adsorption. 3. ABS was initially in most of the activated sludge systems associ- c:ed with the foam phase but there was some adsorption on the microorganism in all i>e systems. The amount of ABS associated with microorganisms was dependent on i»e type of microbes present or the substrate to which they were acclimated. In (if case maltose grown cells adsorbed the most ABS. The amount of ABS adsorbed vis as high as 1.97 rug per gram of cells. The ABS degradation in the Metrecal vstem was very high, about 3k per cent as compared to the 62 to 75 for the other !'Stems. The complexity of the substrate Metrecal seemed to have increased the hS removal per cent as compared to the simple substrates like dextrose and maltose The adsorption of ABS on the microorganisms followed to some extent the feundlich isotherm. The collapsed foam recirculation procedure was suitable to i^tain the ABS in the system. 4. Sand filtration as a means of ABS and phosphate removal was suitable I some degree. The ABS and phosphate removal decreased with the increase of f'draulic loading. The intermittent dosing was effective for the removal of ABS 103 and phosphate, twelve times a day dosing seemed to be more efficient than four times or once a day dosing. Complex substrate (bactopeptone) produced a higher ABS removal in the sand column substantiating the results of the activated sludge studies with Metrecal. Adsorption and degradation or assimilation were both important in the soil system removing ABS and phosphates. Initially before proper growth of microorgani sms, adsorpt ion was predominant but later assimilation was more important when all the adsorption sites were covered and active microbia population was present. The ABS and the phosphate adsorbed could be eluted by tap water and this increased the removal characteristics of the soil column con- siderably immediately following the elution. 04 VII. BIBLIOGRAPHY 1. Weaver, P. J., "Review of Detergent Research," Jour. Water Poll. Control Fed., 3i, 288 (I960) . Lynch, W. 0., and Sawyer, C. N., "Effect of Detergent on the Oxygen Transfer in Bubble Aeration," Jour. Water Poll. Control Fed., 32., 25 (I960). 3. Ammon, F. V., "Damage by Detergents in Sewage Works," Munch. Beitr. Abwass., Fisch.-u. Flussbiol., 9, 215 (1962); Water Poll. Abs. (Brit.), 37, 1323 (1964). k. Schoenborn, W., "Breakdown of Synthetic Detergents in Conventional Sewage Treatment Plants," Gas-u. Wasserfach (Germany), 103 , 1133 (1962); Chem. Abs. 58, 4292 (1963) . Sweeny, W. A., and Foote , J. V., "A Rapid, Accurate Test for Surfactant Aerobic B iodegradab i 1 i ty ," Jour. Water Poll. Control Fed., 36_, 14 (1964) 6. Swisher, R. D., "LAS; Major Development in Detergents," Chem. Eng. Progress, 60 , 12, 41 (1 964) . 7. Flynn, J. H. , Andreoli, A., and Guerrera, A. A., "Study of Synthetic Detergents in Ground Water," Jour. Amer. Water Wks. Assoc., 5_0, 1551 (1958). 8. Deluty, J., "Synthetic Detergents in Well Waters," Pub. Health Reports, 75, 75 (I960). 9. Schmidt, 0. J., "Significance of Detergents in Water Pollution Control," Pub. Wks., J_2, 93, 12 (1961) . 0. Walton, G., "ABS Contamination," Jour. Amer. Water Wks. Assoc, 52., 1354 (I960). 1. Nichols, S. M., and Koepp, E., "Synthetic Detergents as a Criterion of Wisconsin Ground Water Pollution," Jour. Amer. Water Wks. Assoc., 53, 303 (1961). 2. Lauman, C. W., "Effect of Synthetic Detergents on the Ground Waters of Long Island, N.Y.," N .Y . State Water Poll. Control Board Research Report No. 6 (I960) . 3. Ewing, B. B., and Banerji, S. K., "Effect of Biological Slime on the Retention of Alkyl Benzene Sulfonate on Granular Media." Proc. 17th Ind. Waste Conf., Purdue Univ. Ext. Ser. JJj^, 351 ( 1 963) - 4. APHA, Standard Methods for the Examination of Water and Wastewater, 11th Edition, 246 (i960) . 105 5. Cohen, J., personal communication. 6. Robeck, G. C., Cohen, J. M., Sayers, W. T., and Woodward, R. L., "Degrada- tion of ABS and Other Organics in Unsaturated Soils," Jour. Water Poll. Control Fed., 35., 1225 (1963). 7. Klein, S. A., Jenkins, D., and McGauhey, P. H., "The Fate of ABS in Soils and Plants," Jour. Water Poll. Control Fed., 35., 636 (1963). 8. McGauhey, P. H., and Klein, S. A., "Travel of Synthetic Detergents with Percolating Water." Paper Presented at the 19th Ind. Waste Conf., Purdue Univ. 1964. 9. McKee, J. E., and McMichael, F. C., First Annual Report on Research on Waste Water Reclamation at Whittier Narrows, W. M. Keck Lab. of Env. Health Eng., Calif. Inst, of Tech., Pasadena, Calif. (Sept. 1 96 3 ) . Hartmann, L., "Studies on the Removal of ABS by the Microorganisms," Biotech, and Bio-eng., 5, 4, 331 (1963). Suess, M. J., "The Effect of Soil Properties on the Adsorption of Alkyl Benzene Sulfonate," Sanitary Engineering Series No. 14, Department of Civil Engineering, Univ. of Illinois, Urbana, 111. (Jan . 1 963) • Suess, M. J., "ABS Adsorption on Soils," Jour. Water Poll. Control Fed., 36, 1393 (1964). 3. Ghosh, S. N., "The Effect of Chemical Composition of Alkylbenzene Sulfonate on Adsorption by Soils," Sanitary Eng. Series No. 16, Department of Civil Engineering, Univ. of Illinois, Urbana, 111. (June 1 963 ) - \k. Davidson, D, T., and Sheeler, J. B. s "Cation Exchange Capacity of Loess and its Relation to Engineering Properties," Symposium on Exchange Phenomenon in Soils. ASTM Pub. No. 142 (1952). 5. Weber, W. J,, and Morris, J. C., "Equilibria and Capacity for Adsorption on Carbon," Jour. San. Eng. Div., Proc. ASCE, 90, Part 1, 79 (June 1964). !6. Wayman, C. H., and Robertson, J. B., "Adsorption of ABS on Soils" Proc. 1 8th Ind. Waste Conf., Purdue Univ. Eng. Ext. Ser. JM5_, 523 (1963). 7. Malz, F., "The Behavior of New Detergents in Aerobic Treatment of Sewage," Munch. Beitr. Abwass. Fisch.-u. Flussbiol., 9, 266 (1962). Water Poll. Abs. (Brit.), 3Z, 272 (1964). McGauhey, P. H., and Klein, S. A., "Removal of ABS by Sewage Treatment," Sew. and Ind. Waste, 3J_, 877 (1959). !9. AASGP Committee Report, "Determination of Orthophosphate , Hydrolyzable Phosphates and Total Phosphates in Surface Water," Jour. Amer. Water Wks. Assoc. , 50, 1563 (1958) . 06 ?0 McGauhey, P. H., and Winneberger, J. H., "Studies of the Failure of Septic Tank Percolation Systems," Jour. Water Poll. Control Fed,, 36, 593 (1964) . 31 Robeck, G. C., Bendixen, T. W , , Schwartz, W. A., and Woodward, R. |_., "Factors Influencing the Design and Operation of Soil Systems for Waste Treatment," Jour. Water Poll, Control Fed., 36_, 971 (1964). 32. Hsu, C. C., "Removal of Phosphates in Secondary Sewage Treatment Effluent by Sand Filtration," Sanitary Engineering Series No. 23, Department of Civil Enginee ring, Univ. of Illinois, Urbana, 111. (May 1 SGk) . uNivihsirror iuinois uriama 3 0112 027806527