C 2.. m m um “mm A. .. ”5. V: fim 9.“ MW 3 a. .2. C MM .5. 9% E... b.- 3 fix H... t... P... ”mm. a.“ Q m «CU Cu .5 “w. K 0 "MW... m...“ w a er... Eh Jaw... _:_:Egflgrzi,=3:_:_2;:,:_,:_,:;:_,:J_, mm "13 Eagt‘m a? M. “. THESiS This is to certify that the thesis entitled EFFECT OF SODIUM CUPROCYANIDE ON TRICKLING FILTER OPERATION presented by RICHARD w. BRADI', JR. has been accepted towards fulfillment of the requirements for Master's degree in Chemical Engineering WW Major professor Date August 18, 1960 0-169 LIBRARY Michigan State University EFFECT OF SODIUM CUPROCYANIDE ON TRICKLING FILTER OPERATION By RICHARD WINTHROP BRADT, JR. A THESIS Submitted to the College of Engineering Michigan State University of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Chemical Engineering 1960 G/afiéf IQ-QI*U° ii ACMOMEDGMT The author wishes to express his sincere thanks to Dr. C. Fred Gurnham, whose constant interest, timely suggestions, and patience made the experimental work and the writing of this thesis possible. IMuch assistance was given by Mr. Frank Roenicke, undergraduate student in the Department of Chemical Engineering, who conducted numerous analyses essential to the completion of this work. The author also wishes to thank Mr. William B. Clippinger of the Department of Chemical Engineering, for his work and suggestions in the construction of necessary experDmental apparatus for this shmy. The writer deeply appreciates financial support by the National Institutes of Health under Grant No. G—3681. EFFECT OF SODIUM CUPROCYANIDE ON TRICKLING FILTER OPERATION By RICHARD WINTHROP BRADT, JR. AN'ABSTRACT Submitted to the College of Engineering Michigan State University of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of NMSTER OF SCIENCE Department of Chemical Engineering 1960 iv RICHARD WINTHROP BRADT, JR. ABSTRACT. Considerable interest has developed during recent years in the biological oxidation of industrial wastes. WOrk has been done on trickling filters concerning the effects and the ultimate destruction of simple and complex cyanides common to metal finishing wastes. Little data has been compiled, however, on the effects and the ultimate fate of the heavy metals associated.with these complex cyanides. This investigation was primarily concerned with establishing a material balance on the copper in sodium cuprocyanide [Na20u(CN)3] during its passage through a trickling filter. Four small single-pass trickling filters, each three inches in diameter and two feet deep, were operated for three to four months. The feed was settled sanitary sewage, alone or with sodium.cuprocyanide and caustic added to simulate electrOplating wastes. The effluent from each trickling filter flowed into a separate settling tank. AnalyseS'were made on both influent and effluent liquors for BOD, cyanide, and c0pper. Sludge samples from the final settling tanks were dewatered and analyzed for residual copper. These data were then compiled to illustrate the change in concentration of copper in the effluent liquor with respect to influent concentration and time. The influents were fed to the trickling filters at a rate of 14 to 18 cubic feet per square foot per day. The BOD reduction averaged 80% on sewage alone with an organic loading of 127 pounds of BOD per 1000 square feet per day. At this organic loading; the sodium cupro- cyanide concentration was gradually increased from.0 to 7.6.mg/L (CN)-. The BOD reduction temporarily decreased to 37%5 and then recovered to 55%5 remaining constant to the end of the run. RICHARD WINTHROP BRADT, JR. Only traces of cyanide were found in the effluent at the low concentrations of sodium cuprocyanide initially present in the influent. The cyanide concentration in the effluent ultimately reached and remained at 2 to 2.5 mg/L (CN)‘, when the influent concentration reached 7.6 mg/L (CN)-. At an influent concentration of 7.6 mg/L (CN)', equivalent to 5.0 mg/L Cu, 80% of the copper passed through the trickling filters. This is far in excess of that associated with the cyanide remaining in the effluent. Sludge analyses indicated that high concentrations of copper appeared in the sludge. Upon reaching maximum influent cyanide concentration approximately'0.30% Cu was found in the dried sludge, and at the completion of the run approximately 1.50% Cu was present. The filter growth showed no apparent visual changes attributable to the c0pper at any time during the experimental run. Although no samples of the filter slime were taken, it may be concluded that the concentration of cOpper in the slime is approximately equal to that in the sludge collected in the settling tanks. This appears to be a reasonable conclusion based on the continuous sloughing observed throughout the entire experimental run. APPROVED: NbJor Professor ‘"“““r~~l.\ Acknowledgement . . Abstract . . . . . Table of Contents . List of Figures . . Introduction . . . . . Survey of Previous WOrk Experimental Procedures Presentation of Results Smary........ Conclusions . . . . . . Suggestions for Further TABLE Wbrk Bibliography 0 o o o o o o 0 Appendix . . . . . . . . . . OF CONTENTS Page ii iv vii .1:- 27 31 33 35 37 Figure Figure Figure Figure Figure Figure Figure Figure Figure II III IV VII VIII LIST OF FIGURES Experimental Trickling Filter . . . Flow Diagram.- Trickling Filter . . BOD Data Trickling Filters No. l, 2, and h BOD Reduction Trickling Filters No. l, 2, and h BOD Data TriCfling Filter N00 3 o o o o o BOD Reduction Trickling Filter No. 3 . . . . . Cyanide and Copper Test Data Trickling Filters No. l, 2, and 4 Cyanide and Copper Test Data Trickling Filter No. 3 . . . . . Copper Calibration Curve . . . . . Page l2 13 18 19 23 2h INTRODUCTION INTRODUCTION The discharge of cyanides and cyanide wastes directly into streams and municipal sewerage systems is a.matter of grave concern. Only low concentrations can be permitted, owing to the toxic nature of these wastes. The toxic effects of cyanide on human and animal life, even in extremely low concentrations, are well known. The heayy'metals often associated with cyanides, particularly in electroplating wastes, are also toxic. Copper has been found to be toxic to fish in concentrations as low as one milligram.per liter. Possibly more important than these direct toxic effects are the effects on.microorganiams in streams and sewerage systems. Sudden shock loads of cyanides can seriously inhibit the biological activity in a secondary treatment plant, allowing a heavy organic waste load to reach the river or stream, Similarly, in a stream, heavy metal salts and cyanides may immobilize the bacteria, retarding "self-purification" of the stream, and allowing it to become so polluted that it creates a public nuisance and health hazard. Such waters are often incapable of retreatment for human consumption by conventional.means. Recent studies have demonstrated that trickling filters may be a.means of destroying cyanides alone or in the presence of sanitary sewage. These investigations (23) have established the method as yielding a 97 to 99.9% destruction of cyanide in solutions containing sodium, potassiuma cadmium, and cOpper. Less is known about the toxic effects of metals present in complex cyanides during this type of treatment. The present investigation is concerned with establishing a material balance on the copper in sodium cuprocyanide [NaQCu(CN)3] during its passage through a trickling filter. SURVEY OF PREVIOUS WORK SURVEY OF PREVIOUS WORK Early interest in the effects of simple and complex cyanides on biological sewage treatment arose during the period of Wbrld war II, with expansion of the metal finishing and electrOplating industry. Plants using cyanides had been able, previously, to dispose of wastes to normal watersheds or municipal systems, because adequate dilutions were obtained in.most cases, and stream pollution was not of great public concern. Rapid expansion of these industries during world war II focused attention on this problem and hastened the definition of allowable limdts for discharge of cyanide-bearing wastes to streams and municipal sewage treatment plants. There are two predominant methods of aerobic biological treat- ment of sewage: The activated sludge process and the trickling filter. Both methods employ a zoogleal mass of microorganisms which oxidizes the organic matter. In the activated sludge process, a liquid suspension of the organisms is maintained in an aeration tank; while in the trickling filter the mass is supported on a stone or other filter medium. The earliest reported work concerned the activated sludge process. In 1936, Wboldridge and Standfast (31) reported that 200 mg/L of cyanide or the vapors from solid potassium cyanide completely inhibited bacterial action. In 19%, Nolte and Bandt (2o) operated a modified method, known as the Madgeburg process, with butyrates or mscresol as the organic substrate. They reported that the bacteria were inhibited by shock doses of 5 mg/L KCN, but subsequently recovered. At 62 mg/L, after acclimatization, the effluent was found to be free from cyanides and butyrates. When normal activated sludge was supplied in the recycle, 330 mg/L KCN did not interfere with oxidation of the butyrates. Similar results were reported using m—cresol as the organic substrate. In 19h7, Lockett and Griffiths (18) reported 5 mg/L HCN as being definitely inhibitory to activated sludge, and found acclimatization extremely difficult and only partially successful. They were able to acclimate activated sludge to l-mg/L HCN and concluded that, in low concentrations, cyanide is inhibitory rather than lethal to bacterial life. In 19h9, Coburn (6) found that 5 mg/L HCN resulted in partial inhibition of activated sludge and that 20 mg/L HCN caused complete inhibition. The sludge subsequently recovered when the cyanide was withheld for a period. The earliest reported work on the trickling filter process is that of Pettet and Thomas (at) in l9h8. They noted that the BOD of the filter effluent was not affected by less than 1 mg/L HCN in the feed. Increasing the cyanide to 2 mg/L HCN had little effect on BOD but nitrate formation was somewhat retarded. The increase to u mg/L HCN in the feed resulted in an increased BOD in the effluent, and nitrification was more markedly retarded. Similar results were found at 10 mg/L HCN. These effects disappeared after the filter had been in contact with stable concentrations for a period of time, and the cyanides were destroyed to a considerable degree. When the cyanide was increased to 30 mg/L HCN, nitrification was completely stopped. About two months were required for acclimas tization at this concentration. Total nitrogen in the effluent was then found to be greater than in the control, presumably due to conversion of cyanide nitrogen. In 1951, the water Pollution Research Board (Great Britain) began a series of experiments which have continued to the present time. An initial objective was to determine the effects of simple and complex cyanides on trickling filters. Findings were reported in 1951 (8) from a series of small scale trickling filters Operating on KCN and a number of the complex metal cyanides. The report indicated 1 mg/L HCN had no effect on effluent BOD, but the permanganate oxygen demand rose above that of settled sewage for a period of seven days. Upon an increase to 2 mg/L HCN, the effluent BOD increased, while the permanganate oxygen demand remained stable. Some retardation of nitrification was observed and the filter returned to normal in about two weeks. Only traces of HCN, no more than 0.01 IQMI, appeared in the effluent from all the filters except those operating on potassium ferrocyanide. In.the latter case, 0.2 to 0.3 mg/L HCN'was consistently reported. In 1952, the water Pollution Research Board (9) reported findings based upon a continuation of the same series of experiments. They concluded that the complex cyanides of cadmium, zinc, and copper were similar to KEN in.their effects on effluent quality, and that nearly complete destruction of cyanide was possible in concentrations up to 100 mg/L HON. At 200 mg/L HCN, 80$»destruction was not uncommon. At 100 mg/L HCN, from 50 to 100% of the nitrogen from the cyanide could be accounted for in the effluent as ammonia plus nitrite plus nitrate. Ferrocyanide, apart from the fact that nitrification was much.diminished at concentrations above ho mg/L HCN, differed completely in behavior from.the other cyanides. It had no discerns ible effect on effluent BOD, and from.30 to 80% of the cyanide passed through the filter unchanged. The effect of nickelocyanide was intermediate between that of ferrocyanide and that of the less stable complexes. In 1953, the Water Pollution Research Board (10) continued this series of studies with the revised objective of deve10ping a suitable means of biologically treating cyanide-bearing wastes. Results reported at this time indicated that simple and complex cyanides could be nearly completely destroyed in a trickling filter operating in the absence of organic nutrient. Complete destruction continued even at a concentration of 160 mg/L HCN. The treatment of cuprocyanide and nickelocyanide was less successful, and only 20 to 30% of the cyanide in.the ferrocyanide was destroyed. A.pr0portion of each of the heavy metals was found in solution in the respective filter effluents. The concentration of iron corresponded well with that calculated from the observed cyanide as ferrocyanide or ferricyanide. The concentration of other metals in the effluents was more than equivalent to the cyanide present. In 1951+, the Water Pollution Research Board (11) attempted to isolate some of the microorganisms present in a cyanide-acclimated filter in order to determine the mechanisms involved in the destruction of cyanide, and to determine the depths at which destruction was essentially complete. A.trickling filter was operated in conjunction'with a commercial firm, on influent composed of mixed complex cyanides in water solution. Satisfactory treat- ment was obtained; in fact the average concentration of cyanide in the effluent was less than would have been expected.had 100% of the cyanides of potassium, zinc, and c0pper, and 80% of the ferrocyanide been destroyed. About 50% of the cyanide nitrogen appeared in the effluent as ammonia plus nitrite plus nitrate. In 1951+, Daus (7) reported data from an experimental run using two trickling filters each six feet deep. The results were in general agreement with previous data indicating a noticeable decrease in BOD reduction when cyanide in the influent exceeded l‘mg/L (CN)". Additional data Obtained by culture growth of bacteria extracted from the filters indicated that cyanide toxicity to microorganisms is a function of the nutrient medium supporting these organisms. The cyanide toxicity involves increased lag periods rather than decreased p0pulation levels. Cyanide exerts a bacteriostatic action. In 195M, Southgate (29) published a survey of current technology of the treatment of waste water containing cyanides. He particularly stressed the recently reported work by the water Pollution Research Laboratory. ‘ Similar data was presented in 1954 by Pettet and.Mills (25) of the water Pollution Research Board in which they emphasized the develOpment of commercially feasible biological methods for the treatment of cyanide-bearing wastes. They reported recent success in the treatment of cyanide-bearing wastes in the absence of organic nutrient. Also presented was data indicating the development of a "carryaover" resistance to cyanides of up to two weeks, suggesting the poSsible use of’a trickling filter in the bio-oxidation of cyanides intermittently present in a waste disposal system. In 1955, Gurnham.(16) presented a paper at the 10th Purdue Industrial wastes Conference which summarized earlier work of the water Pollution Research Board. Data concerning the effects of cyanide-bearing'wastes on sewers and sewage treatment processes agrees with that presented here. Particular emphasis was placed upon cyanide destruction on trickling filters and the imminent development of commercial plants utilizing biological techniques to treat metal-finishing wastes. Additional data indicated that a considerable amount of cyanide was converted to ammonia in the tOp foot of a 4-foot filter. Nearly all of the cyanide was destroyed at the two-foot level. It was noted that the (CN)- ion rather than the complex metallocyanide is the inhibitory agent. This explains why the more stable complex cyanides have less effect on sewage purification.in.a trickling filter than the simple cyanides at equivalent concentrations. In 1955, the water Pollution Research Board (12) ran a series of tests utilizing a fifteen-foot filter in an attempt to Obtain a greater area utilization and possibly to exceed the accepted application rate of h.5 cubic feet per square foot per day. It was found that cyanide in concentration of up to 68 mg/L HCN and flows of 12.3 cubic feet per square foot per day could be easily tolerated and that nearly complete destruction took place in the top 6.5 feet of the filter. They subsequently Observed that the greatest concentration of a cyanide- destroying bacteria occurred at a depth Of 5.5 feet. In 1956, the Water Pollution Research Board (13) continued previous tests on a fifteenefoot trickling filter. They concluded that a greater capacity could not be attained.by increasing the cyanide concentration in the feed beyond 60 mg/L HCN. They reported that at this concentration essentially complete destruction of cyanide was attainable at a feed rate of 60 cubic feet per square foot per day. They also reported that greater volumetric efficiency was possible in filters containing specially graded support mediums. A.fourhfoot filter, using No. 7 British Standard Screen to three-sixteenths inch graded gravel was reported as successfully treating at least 12 cubic feet per square foot per day at a concentration of 56 mg/L HCN. Essentially complete destruction was reported under these conditions. This filter also Operated satisfactorily on an intermittent basis, i.e. eight hours on stream and sixteen hours off, suggesting its adaptability to a process Operating on one shift per day. In 1957, the Water Pollution Research Board (11+) operated an experimental pilot scale filter four feet in diameter and six feet deep, containing 2.8 cubic yards Of three-eighths inch gravel. The results indicated that at least 21.6 cubic feet per square foot per day of sodium cyanide solution containing 60 mg/L HCN or 19.h cubic feet per square foot per day Of sodium cyanide feed containing up to 90 mg/L HCN could be treated under industrial conditions yielding an effluent containing less than 1 mg/L HCN. In 1958, Ware (30) of the Water Pollution Research Board reported that the biological destruction of cyanide is affected by temperature. There is little effect in the range of 10° to 35° Centigrade, but at higher or lower temperatures, biological activity is inhibited. FDCPERD’IENTAL PROCEDURES ll EXPERIMENTAL PROCEDURES Four laboratory trickling filters were set up and Operated for a period of three to four months, using a feed stock of settled domestic sewage with simulated electroplating waste added in controlled quantity. Feed rates were controlled in the range of 1% to 18 milliliters per minute, equivalent to 1h to 18 cubic feet per square foot per day. Periodic samples of influent and effluent liquor were analyzed for those variables necessary to develOp satisfactory material balances and control data. The trickling filter units (Figs. I, II) were glass cylinders so packed as to make an effective bed 24 inches high and 3 inches in diameter, having a cross sectional area of 0.0h9 square feet. The filter media used was 12 by 12 millimeter Pyrex Raschig rings. These filters were placed on small settling tanks having an over- flow weir as illustrated. .A sample tap was provided for effluent liquor samples. Sludge samples were taken by decanting the liquor and recovering the wet sludge. The overflow provided a continuous discharge Of effluent from the tanks. The basic feed stock was domestic sanitary sewage, free from industrial wastes, obtained from the primary settling tanks at the East Lansing municipal sewage treatment plant. This sewage was continuously pumped into a large storage tank with overflow weir, located inside the laboratory building. The holding tank served to equalize short time fluctuations in organic content and other variables of the sewage. The individual trickling filter feed tanks were filled daily from.this storage tank. The required amounts of sodium cuprocyanide stock solution were added to the feed stock in the individual supply tanks and thoroughly mixed. The standard stock solution was a specially prepared and analyzed solution of sodium cuprocyanide in demineralized water containing one part of sodium hydroxide per 7.5 parts of the complex cyanide, to stabilize pH and prevent the formation and loss of hydrogen cyanide gas. l2 +— g" ' i if !4" i L (,4 av REx TU B’l NG_// 28" I2x l2 MM PYREX .,.' 315$”? R'-')l-§§_/ i i r 1 I i ? OVERFLOW i 35 PEREORATIONS *WEIR __ I ON 3';- CENTERS __.Ef ._ - _ .J ..... 1- _,/—y * 1‘ SAMPLE 6.. TI SETTLING %..QL “ TANK u l4 -—-—-—- 3 f i .1 1 11 Tl -1 1.. (if: ,4 .. p 2 H h ”:2 1 ‘ OUTFLOW ' FIG U R E I EXPERIMENTAL TRICKLING FILTER 13 mwhuzu OZJXUEH III 2 xxx xxx xxx mxz-- -..I>.—_.._._I . . . I I L . .IIIIATI 1; ,I- I I‘ I .. . I . : 43191.: ' C) '0 . I. .Vd I. I t iu.~ Q1. dB } UL! .l,vdU,. 1‘ but" ‘ CD ‘3 be I (II-J. (.51.. .. 1‘ AVT. ..: I l9 fl H I”. . « “ I“ .I . 1 . . w l: _ .—. 11 1 1 H . .l . 1.. d 0 n IAIIILr IIIT p III]. II 4 I 161v 0?. m . 1 _ g; .1 .3 I . 1. . . . .. 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I . ..v . . . .1. .w...44 22 equivalent to l2? pounds of BOD per 1000 square feet per day and 6.7 pounds of (0N)- per 1000 square feet per day compared to 3.5 pounds of (CN)- per 1000 square feet per day in the earlier'work. Reported on this basis the effect on sewage purification efficiency is not entirely'unexpected. Only traces of cyanide were detectable in the effluent during the early stages of the experimental run, After a period of Operating at 7.6 mg/L (010" in the influent, the effluent contained from 2 to 2.5 mg/L (CN)‘. This represents a 60 to 75% reduction of cyanide at a loading of 6.7 pounds of cyanide as (UN). per 1000 square feet per day. These high cyanide loadings suggest the possibility of develOpment of a high efficiency trickling filter for industrial wastes, with increased depth and with a synthetic media having a high surface area and a high percentage of voids. The primary Objective of this investigation was to trace the copper in sodium.cuprocyanide through a trickling filter and to determine its ultimate fate and its effect, if any} upon the filter itself. Figure VII and VIII show the concentration of copper in both influent and effluent liquors from all of the filter units. In Filter No. 3, the concentration of c0pper in the influent was increased rapidly to 5 mg/L and then held constant. The other units were fed settled domestic sewage for some time before cOpper was added to the influent. The concentration of cOpper was then increased gradually to 5 mg/L at the end of the test period. The effluent copper concentration increased with that of the influent and then remained quite constant at about It mg/L or 80% of the influent concentration. The occasional erratic results shown on Figure VI*C are attributed to the observed heavy sloughing of the filter at that time. 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V V. .V V V V... . V V. .V ... V V V. .a.. ... V V. ... .V V V V . V, L V1 IOOIJV 4‘ V V V . . V V. . .V . V. VV ..V. V .V V V . ...V . V..V ... V .... V V V .V V.. . .u . V V . V V. o . V V . . .V V... V... . V . .V ... V. n, V V V V V V n... .V V V V V a... .... I V V _ V. V. V. ... V . V. V .0. . V. V . . .V V V V. V. V... .V V .flVV V... V V oac‘ V . V. .V V V V. v V V .V.- V. . V. V V V VV V V - V V V V v.. ...V o o. V... .V V .. V. .V V . ... V V V. V. V. V .... V V V V. ... .V V V . ...V V V . V V r r F 4 4 V 4 . .VVA . V. V . . . . v V..v V. c... V. V . V V. V. V V... V. .V . .V .... V. A V <.«v . V V do V. V V '.V V . ... .V V . .oV V ... .... V. . V V VV. V V V .. ¢¢ . V. V V .... . V V V V. V V .V ... V. ... V. V.. A ..v ... .... o . ... . ... . V . V V V VV V. V . V_VV. Vu_. olv“. V. V V. V.’ V. Q. o VV 4. V _ V V... V .... . aV V .4 .h.> V V n V ... ... . — V a . ‘ V V. V o... . V . V-.. V... ... V A V. 0. V V . 1V . V . V. V. .V. V VV. V .. .... .V. .VV. v. . AVo V V .V .V V V V .... ..A. V H. . . V. V. ... . ..V V.. v V ... . V.- n V V. V. V. V. ...v V... V .V VV . ... .VV. V. . V V V .V . V V V < .V - <0 A. V. _. V 9 ..V V V. c .V V. ... . . A V. VVV. V A V:V - ... ... v. V V V . V ... VV . V V... V . .VV. 4 ..VVI‘ .1 vl'tlll <4 V. ..V. 0. V V ... . . .V V .V o . V V. V . ... .V V V V V. . ... V V V... . .V .V. . ...-AV V. V» V V V .... . v .. V. _. V V .. ... V H V. .V V V. V o . V... . .... ... V... V V ..ko .V ... ...V+.V. V V V. V v. VVov V. . ...: . V V . V V V. .V V V V. V .V .V V. V .V .V . . V V .... V V ..p. a V. ...V V V . V. .... V ... .V . V. V ... V V. V V. V? V . . V. V V.» . . .V ... V VV+..VVVV I. V V ... V. ... _V V V ... V. V V 41 «VM ... .9. V V V . V V . V V V V... . V. V V . V V. VV V V . V. V. .V. .... V V e V. . V. V ... V V V . V . . V. V .V V . V V. . V ... .V ... V... V 4.. V. V. .. V V V V V V V . V V . V V . V V V V V V V VV V . V V V V. V . . . . V... V. n :0 V. o . +41 P {J V V 1V“... . V . v ..V V . V .V - . V A. . V V ... .V .V . V V_. ..V . ... V... V. V V V .V V V V V. V .q . V n V .V ... V . .V . V . V V.. V. .VV... V. V. V. V V... . V V V V 1 V V t V. V V V o... V .V ... V V V. V I V . .0. . I o l. n .- . .II t ‘ J O D .I . V ‘— V V V V V . V... .V . . . V. VV .V o. VV A V - VVV V V. V V». . u . . . V V. V. V V .V V. r’. il .L! ITIIV JTVVIJVIII L . V V V VVVl V »L V V}> L VVL w . . V V V V V U V . .V c . V. . V V V .. t . V .. V.. V V V V V V. . V VV V V . V V V . . . V? V. V. V V < . I u. . d. . -v t . 1 .- It A V. V V V . V V V V. V. . V . V . V V AVlu V V V V V V o. V . . VV V V . . V V.. V. . .V V V . V V .... . V . V V VVo V V . V V V. V .n u o V V. V. ... V V V .VV V .V .V .V V .. V . . .. V V i. V V V. V 0 .V V V . V V V V V VW . VV V .V V V V V . V .V V V .VV . .vv V V V. V. V. . . V V V . ... V V. . . V V . V V V. V V .V V V . V V V V V . V .V V V . . ..V o . V V ...V. V V . VP. V-V' bl”. . .V V . V V V.” . V V V V .r. . .1 > V. . n‘ a h H V V. .... .V .... .V V .V . V . 4 D V .- . .. ... . V .c .'-V V.. V . u I In‘ a. V V . V. 0 V n . t u ‘ V V V. V .V V . .... V V aVl V o. ..V. V. .. VVV V. L V V ...V V V V V . .V 4 V V ... V. V V V V V... . VV . V .V V . .V . V V.v ... V .V. V. V. . .v V. V VVw. V. . ... V... V. ...; V V V V V V ... V V 1].. ..v V V . V V. V ... V ... . .a.. V . ... V V V V V. V. V V. V . V... V .VV V V . .l I‘VVVVI‘I . T1 b V . V .. . _- VV. V V V V V V I. V. . V o V V V c or .V V V V... V . .V . V V V V V V V V. .V V . V. . .V .V . . V V. V V . . V. V. V V _ .1 1 V V m*0. .. . . V. V. V V V n . . V V. > V V . V V V ..a . < V. V. v VVV. .. V .o .- . V A. V . e. ..V c. 0 V V a . V V V 4 4 u ‘q 1‘ 4‘4 ..Vv .... v n V. ... ... v". v-.. Vo¢oAV+VV V... V o VVV.V. . Vfi‘w. V.FVV.A. ... V_ . . V . V V V V a V.. VAA H. .0 V V. V V. V. V A V V . . V . .V V .V . V. a V. 0.. .Fo. ...J 0. V V. ¥ ... ... V.. V . . a V. bl J’hV >< v" 0 V V. V.. V V., V V. V.... .. VVV~ o A. . V VVV pH. .? i i '15: V - V V... TH. ... VB, . .V V. . V. . . V- . V. V fi‘ V. .V . . V. V... ....-. VV - V . V ... V V .. . >41 0* ‘VVVTVV. V. V V 9.; V. V V. V .... ... V ... V V. V V. V . V- . .v V o o V v 7.. V. V _ It V 4.4- » no. ... V . Jfigalle 9:6. 1 o.5 .woo V. 4. . .V V V. .V V VV.V o. o. .0. ... ..Vlo .. . ov n. .V.VL ‘3» ¢ .. .d. a. V V VI . V... V V. H... . .8 V o. 7 - .VVV ...?VAVM ; fo.7.VI.V ..VVV5»V~ VVVV VVu V... V .. VV V V. V... ... V. V V . .Yv . VV .. . V . . A . .V .VIVV nVOVg V .. ..-. V... .QVu ..l« ..V . V . . V? >LF . p . V > .L a V V- M.“ .4 g V... VVrV¢ V V... OOI.V ..HV fl.v 1...». o-.. V V_ .01 4 V... V. . ¢ V. ... r r? L > > V L >? r 25 the end of the test period on Filter No. 3, additional sludge samples showed a copper concentration of 1.52 % Cu (dry basis). No samples of the filter slime itself were taken for analysis; however the rate of sloughing suggested that no appreciable accumulation of copper would be found and that all of the cOpper 'would ultimately be found in the filter effluent, either in the liquid or the sludge. SUMMARY 27 summ This investigation was primarily concerned with establishing a material balance on the c0pper in sodium cuprocyanide [Na20u(CN)3] during its passage through a trickling filter. Data was also taken on BOD and cyanide reduction for comparison.with results reported earlier by the water Pollution Research Board of Great Britain. General agreement was found between the results of this investigation and those of the earlier work with few exceptions. Four small scale trickling filters were Operated for three to four months on a feed.made up of settled domestic sewage and sodium cuprocyanide. Numerous analyses were made of both.influents and effluents for BOD, cOpper, and cyanide. Sludge samples from.the final settling tanks were dewatered and analyzed for residual copper. This data was then compiled to illustrate graphically changes in.the concentration of copper in the effluent liquor with respect to influent concentration and time. During the initial start-up of the trickling filters, considerable difficulty was encountered with ponding and localized clogging and the subsequent development of anaerobic conditions. mass sloughing soon develOped and the filters became biologically inactive until new biological growth developed. This condition was substantially corrected by replacing the support media with larger Raschig rings having a greater percent of voids and larger individual voids. Further improvement was effected by incorporating intermittent siphons into the feed system.to provide intermittent dosing of the filter units. The problems were attributed to the restrictively small void spaces together with heavy continuous hydraulic action. Settled domestic sewage, alone or with simulated electroplating wastes, was fed to the single pass trickling filters at 14 to 18 cubic feet per square foot per day. The BOD reduction averaged 80% on sewage alone at an application rate of 127 pounds of BOD per 1000 28 square feet per day. The reduction decreased to 55% in the presence of 7.6 mg/L (CN)- at an application rate of 6.7 pounds of cyanide per 1000 square feet per day. Only traces of cyanide were present in the effluent at the initial low concentration of sodium cuprocyanide added to the influent liquor. The cyanide concentration in the effluent ultimately reached and remained at 2 to 2.5 mg/L (ON)- when the influent concentration reached 7.6 mg/L (CN)". Earlier investigations carried out by the water Pollution Research Board of Great Britain found little or no lasting effect on BOD reduction until cyanide concentrations far in excess of those encountered in this work were reached. Some initial retardation of sewage purification was reported, but it disappeared within two to six weeks of Operation. Similar initial retardation of BOD reduction was found in this investigation but full recovery was never experienced. This can probably be attributed to the higher organic loading (127 pounds BOD per 1000 square feet per day) and the shallow (2 feet) packed bed depths used in this investigation. The water Pollution Research Board also reported nearly complete (97 to 99.9%) destruction of cyanides on a 4 foot deep filter at application rates of up to 1.2 cubic feet per square foot per day sanitary sewage containing 150 mg/L HCN. Application rates of up to 60 cubic feet per square foot per day at 60 mg/L HCN were reported in the absence of organic nutrient on a fifteen foot trickling filter. They also reported that the greatest concentration of cyanide-consuming bacteria occurred at the 5.5 foot level in this latter work. It may be concluded that the reduced cyanide destruction experienced here is the combined result of the high application rate (in to 18 cubic feet per square foot per day), the high organic loading (127 pounds of BOD per 1000 square feet per day), and, the reduced packed bed depths. About 80% of the copper passed through the trickling filter at an influent concentration of 5 mg/L. This is far in excess of that associated with the undestroyed cyanide in the effluent, and is in general agreement with the earlier findings of the water Pollution Research Board. Sludge analyses indicated high concentrations of c0pper 29 at different times during the run. Immediately after acclimatization there was 0.305% to 0.339% Cu (dry basis) present and at the termination of the run there was 1.52% Cu (dry basis). The filter growth showed no apparent visual effects of the c0pper at any time; however, it must be assumed that the copper not appearing in the effluent was retained for some time in the filter slime. An equilibrium.must exist between the old and new growth such that the copper reaches a maximum concentration in the slime after a moderate period of operation. Since no actual slime analyses were made in the investigation, we can only presume that the cOpper concentration is approximately equal to that in the sludge. This seems a reasonable conclusion based on the continuous sloughing noted throughout the course of this work. CONCLUSIONS 31 CONCLUSIONS 1. An 80% reduction of BOD was noted while operating on settled domestic sewage at l)+ to 18 cubic feet per square foot per day. This indicates an excellent efficiency for high surface area synthetic filter media. 2. The BOD reduction decreased to 55% while operating on an influent containing sodimn cuprocyanide equivalent to 7.6 mg/L (CN)-. 3. The cyanide in sodium cuprocyanide was 60 to 75% destroyed at an application rate of 6.7 pounds of cyanide per 1000 square feet per day using an influent containing 7.6 mg/L (ON): 4. Of the cOpper in sodilnn cuprocyanide 80% passed through the trickling filter and appeared in the effluent while Operating on an influent containing sodium cuprocyanide equivalent to 5.0 mg/L Cu. 5. The sludge initially contained about 0.30% Cu (dry basis); this increased to about 1.52% Cu (dry basis) at the end of the run. 6. The c0pper had no discernible effect on the filter slime, and it was concluded from the uniform continuous sloughing that the cOpper concentration in the slime closely approximated that of the sludge discharged from the trickling filter. SUGGESTIONS FOR FURTHER WORK 33 SUGGESTIONS FOR.FURTHER WORK It is recommended that future investigators study the practica- bility of using some of the newer synthetic trickling filter packings, particularly those of the plastic honeycomb type (5), in view of the high cyanide loading rates found allowable in this investigation. These media have a high percent of voids and large individual void spaces, in addition to a high surface area per cubic foot. It is expected that this would completely eliminate the clogging and resultant sloughing experienced in this work. .A further recommendation is to investigate the relationship between influent feed rates and packed bed depths with respect to cyanide destruction. This might prove particularly worthwhile on the type of media mentioned above, since it could well lead to extremely high filtration rates on relatively economical units. Further work is desirable in obtaining slime samples at varying depths within a filter and analyzing for copper or the other heavy metals involved. Continuous sloughing precluded any marked c0pper accumulation in the slime during this work. HOwever, less frequent sloughing and resulting heavier growth might well be expected using a media with larger void spaces. Similar data to that reported in this investigation is probably desirable for other heavy metal cyanide complexes common to the plating industry. It is suggested however, that this be done on modified trickling filters using greater packed depths and an improved packing media as suggested above. BIBLIOGRAPHY l. 16. l7. 18. 35 BIBLIOGRAPHY Aldridge, W. E., "New Method for the Estimation of Microquantities of Cyanide and Thiocyanate," Analyst, 69, 262-5 (19%). Aldridge, W. E., "Estimation of Microquantities of Cyanide and Thiocyanate," Analyst, 79, Ink—5 (191+5). American Public Health Association, "Biochemical Oxygen Demand," Standard Methods for the Examination of WaterL Sewage, and Industrial Wastes, 10th ed., p. 260-7, 1955. American Public Health Association, "COpper," £219., p. 310-11. Bryan, E., "Molded Polystyrene Media for Trickling Filters," Purdue Univ. Eng. Bull. Extension Ser. No. 83, 164-172, 1955. Coburn, S. E. , "Treatment of Combined Industrial Waste and Sewage," Sewage Works g.) g, 522-1; (1949). Daus, G. D. , "The Effects of Cyanide on Trickling Filter Organisms, " Thesis, Michigan State University, 1952. Department of Scientific and Industrial Research, "Waste Waters Containing Cyanide," Water Pollution Research (British), % 31-3. 3212': $222.: 36'9' _I_b_i<_i., 1923, 19-21. no» hit 50—2- _I_bi_d., 1955, 62-h. 95.3.1.9: 3.2%) 511-9- _I_b_i_d., 1927, 67-71. Epstein, Joseph, "Estimation of Microquantities of Cyanide," Anal. Chem., _l_2, 272-1; (191w). Gurnham, C. F. , "Cyanide Destruction on Trickling Filters," Purdue Univ. Eng. Bull. Extension Ser. No. 89, 186-193, (1955). Kruse, J. M., and Mellon, M. G., "Determination of Cyanide," Sewage and Ind. Wastes, 233, 1402-7 (1951). Lockett, W. T. , and Griffiths, J . , "Cyanides in Trade Effluents and Their Effect on the Bacterial Purification of Sewage, " Inst. Sewage Purif. J. and Proc., 121:7, Pt. 2, 121-110. P\ (N a a o o P\\ '\ '\ C n ,n p o a F\ n c J I I r C Y. r a n.\ D r‘\ I Q - Fi\ a (\ r x a v t o o I n 'V o c (a . P 7. P: F‘ r\ 9‘ l I I\ a . I a n\.\ by. a .K t -\ O I . o a p a I\ a; p\ '\ 19. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 36 Ludzack, F. J., MOore, W. A., and Ruchhoft, C. G., "Determination of Cyanide in water and waste Samples," Anal. Chem,,.g§, 1784-92 (1954). NOlte, E., and Bandt, H. J., "Biological Sewage Treatment with Activated Sludge in the Presence of Cyanogen," Beitr. wasser— Abwasser-U. Fischereichemt, Magdeburg, 9-lh (1946). Nusbaumb L., and Skupeko, Peter, "Determination of Cyanide in Sewage and Polluted water," Sewage and Ind. wastes, gfi, 875-9 (1951). Ohio River Valley water Sanitation Commission, "Colorimetric Determination of Copper," Procedures for Analyzing Metal Finishing Wastes, 36-41 (1954). Pettet, A, E. J., "Treatment of Electroplating wastes," Products Finishing (London), 8, No. 7, 54-66; No. 8, 57-63 (1957). Pettet, A, E. J., and Thomas H. N., "The Effect of Cyanides on Treatment of Sewage in Percolating Filters," J. Inst. Sewage Purif:, 1948, Pt. 2, 61-8. Pettet, A, E. J., and Mills, E. V., "Biological Treatment of Cyanides, With and Without Sewage," J. Appl. Chem., 5, 434-44 (1954). Ruchhoft, C. G., Mbore,'W..A., Terhoeven, G. E., Middleton, F. M3, and Krieger, H. L., "Tentative Methods for Analysis of Cadmium, Chromium, and Cyanide in.Water," Bull. 355, Robt..A. Taft Sanitary Eng. Center, Cincinnati, Ohio. Ryan, J. Am, and Culshaw, G. Wk, "Use of p-Dimethyl-Amino Benzylidene Rhodanine as an Indicator for the VOlumetric Determination of Cyanide," Analyst, 69, 370-1 (1944). Serfass, E. J., Freeman, R. B., Dodge, B. F., and Zabban, W}, "Determination of Cyanide in Plating wastes and in Effluents from Treatment Processes," Plating, ég, 267-73 (1952). Southgate, B. At, "Treatment in Great Britain Of Industrial waste waters Containing Cyanides," water and Sanit. Eng., (Oct. 1953). ware, G. G., "The Effect of Temperature on the Biological Destruction of Cyanide," water and waste Treatment J., (March/April 1958). WOoldridge, W. R., and Standfast, A. B., "The Role of Enzymes in Activated Sludge and Sewage Oxidation," Biochem, J°:.§Q’ l5h2-53 (1936). 0v 0.x a \ o O O\ a\ we O f,\ 0 ~\ 4 o o 9‘ pk r\ p\ o 0 Va 9 r\ n n I r x o C c o .,\ ’ \ f‘ 9‘ 0‘ APPENDIX A. EXPERIMENTAL DATA TABLE I, Trickling Filter No. 1 . TABLE II, Trickling Filter No. 2 TABLE III, Trickling Filter No. 3 TABLE Iv, Trickling Filter No. 4 B. ANALYTICAL METHODS Analytical MEthOdS o o o o o o o 0 TABLE V, COpper Calibration Data . Figure IX, COpper Calibration Curve Page 37 38 TABLE I TRICKLING FILTER NO. 1 INFLUENT FEED RATE FETIBENT DATE (ms/ L) (gal/m3 (ms/ L) (1956) BOD CYANIDE COPPER per day) BOD CYANIDE COPPER OCto 15 "' 0000 0000 703 " " " 16 - 0.00 0.00 1237 - - - 17 137 0.00 0.00 2354 27 - - 18 - 0.00 0.00 1550 - - - 19 - 0.00 0.00 1480 - - - 20 - 0.00 0.00 1990 - - - 21 134 0.01 0.01 1917 34 0.0 - 22 - 0.01 0.01 1359 - - 0.01 23 - 0.01 0.01 1577 - - - 24 - 0.02 0.01 1553 - - - 25 195 0.02 0.01 1795 42 - 0.01 26 - 0.03 0.02 1407 - - - 27 - 0.03 0.02 1786 - - 0.05 28 174 0.04 0.03 1456 37 - - 29 - 0.04 0.03 1456 - - 0.04 30 - 0.05 0.03 1529 - - - 31 195 0.06 0.04 1262 - - 0.04 Nov. 1 - 0.06 0.04 - - - - 2 - 0.08 0.05 1238 - - - 3 - 0.09 0.06 - - - - 1+ 180 0.10 0.07 1941 31 - 0.04 5 " O 012 O 008 2038 " "' - 6 - 0.14 0.09 1844 - - 0.07 7 147 0.18 0.12 1674 20 - 0.03 8 - 0.21 0.14 1844 - - 0.11 9 - 0.26 0.17 15fl+ - - - 10 216 0.31 0.20 1456 44 - 0.08 11 - 0.37 0.24 1820 - - - 12 - 0.44 0.29 1430 - - 0.04 13 - 0.53 0.36 1529 - - - 14 - 0.63 0.41 1893 - - 0.14 15 108 0.76 0.50 1334 24 - 0.14 16 - 0.96 0.60 1432 - - - 17 1,10 0.72 1786 - - - 18 "' 1032 0 086 "' " " - 19 - 1.32 0.86 1868 - - 0.32 20 137 1.56 1.02 1456 21 0.0 0.27 21 - 1.86 1.21 - - - - 22 2.20 1.43 1692 - - 0.43 23 - 2.62 1.71 1286 - - - Dec 0 24 25 26 27 28 29 30 106 TABLE I (continued) Nfifigyrwwm $$888$8$8 \nmk-F‘Lfmmmlf 883888588 1698 1795 1698 1359 1698 1650 1698 :EIIEI \n I4:-II 39 da L& 2.69 3.06 4.29 TABLE II TRICKLING FILTER NO. 2 INFLUENT FEED RATE IETHEETTF DATE (ms/L) (gal/m3 (ms/L) (1956) BOD CYANIDE COPPER per day) BOD CYANIDE COPPER Oct . 15 - 0 .00 0 .00 1043 - - - 16 - 0.00 0.00 1650 - - - 17 137 0.00 0.00 152 26 - - 18 - 0.00 0.00 133 - - - 19 - 0.00 0.00 1238 - - - 20 - 0.00 0.00 1601 - - - 21 134 0.01 0.01 1504 28 - - 22 - 0.01 0.01 1359 - - 0.01 23 - 0.01 0.01 1189 - - 0.03 24 - 0.02 0.01 1189 - - - 25 195 0.02 0.02 1189 33 - 0.00 26 - 0.03 0.02 8492 - - - 27 "' O 003 O 002 13.10 "' " O 012 28 174 0.04 0.03 1577 42 - 0.00 29 - 0.04 0.03 1431 - - 0.03 30 - 0.05 0.03 1553 - - - 31 195 0.06 0.04 1359 - - 0.01 Nov. 1 - 0.06 0.04 - - - - 2 - 0.08 0.05 1334 - - 0.13 3 - 0.09 0.06 1504 - - - 4 180 0.10 0.07 995 29 - 0.14 5 - 0.12 0.09 1334 - - - 6 - 0.14 0.09 1456 - - 0.05 7 147 0.18 0.12 1334 23 - - 8 - 0.21 0.14 165) - - 0.05 9 - 0.26 0.17 1310 - - - 1I> 216 0.31 0.20 1553 27 - 0.06 11 - 0.37 0.24 1868 - - - 12 - 0.44 0.29 1237 - - 0.05 13 - 0.53 0.36 1334 - - - 14 - 0.63 0.41 1601 - - 0.20 15 108 0.76 0.50 1383 19 - 0.03 16 " O 096 O 060 1577 " " " 17 1.10 0.72 1407 - - - 18 - 1.32 0.86 - - - 19 - 1.32 0.86 2111 - - 0.14 20 137 1.56 1.02 1007 22 0.0 0.36 21 - 1.86 1.21 849 - - - 22 2.20 1.43 - - 0.48 23 - 2.62 1.71 801 - - DGCO 24 25 26 27 28 29 30 106 TABLE II (continued) “‘2“??? F98”? 8393818883838 \nvn-Pr-F'wmromH 0 oo 01me HOD c>c>$>c>u>u>66c>u> 1553 1213 1383 1359 1771 1553 1650 1698 ogllllllgl 41 0.39 1.92 2.45 3.65 2-73 42 TABLE III TRICKLING FILTER NO. 3 INFLUENT FEED RATE EFFLUENT DATE (me/L) (gal/yd3 (ms/L) (1956) BOD CYANIDE COPPER per day) BOD CIANIDE COPPER Oct. 1 - 0.63 0.41 1553 - - 0.11 2 - 0.75 0.48 1601 - - 0.17 2 - 0.90 0.59 1698 - - 0.14 3 77 1.09 0.77 1698 27 - 0.59 4 - 1.31 0.86 1674 - - 0.71 5 - 1.58 1.03 1456 - - 0.41 6 - 1.87 1.22 1456 - - 0.85 7 .. - .. .. .. - .. 8 - 2.12 1.38 1262 - - 0.69 9 136 2.55 1.66 1189 39 0.50 0.88 10 - 3.06 2.00 1674 - - 1.01 11 - 3.65 2.38 1529 - - 1.73 12 - 4.42 2.88 1674 - - 1.17 13 208 5.18 3.38 1917 94 0.40 1.29 14 - 6.20 4.05 1795 - - 1.67 15 - 6.20 4.05 1189 - - 2.29 16 - 7.47 4.88 1868 - - 2.01 17 158 7.65 5.00 1747 76 0.00 3.01 18 - 7.65 5.00 1553 - - 2.77 19 - 7.65 5.00 1359 - - 2.89 20 - 7065 5000 1795 " " - 21 148 7.65 5.00 1844 77 - 2.37 22 - 7.65 5.00 1456 - - - 23 - 7.65 5.00 1359 - 0.00 3.99 24 - 7.65 5.00 1601 - - - 25 197 7.65 5.00 1723 70 0.20 3.25 26 - 7.65 5.00 1359 - - - 27 - 7.65 5.00 1359 - - 2.85 28 182 7.65 5.00 1601 80 0.00 - 29 - 7.65 5.00 1335 - - 3-99 30 " 7065 5000 1383 - - .— 31 192 7.65 5,00 1626 72 0.00 2.37 NOV. 1 - 7065 5000 " " " ‘- 2 - 7.65 5.00 1577 - - 3.35 3 - 7.65 5.00 2087 - - - 4 140 7.65 5.00 1504 60 2.33 3.55 5 - 7.65 5.00 2087 - - - 6 " 7065 5000 .1650 " 2050 3039 7 144 7.65 5.00 1407 61 - - 8 - 7.65 5.00 1674 - - 3.01 9 - 7.65 5.00 ° 1237 - - - D800 10 12 13 14 15 16 17 18 19 22 23 24 25 26 27 28 29 3O 1 216 108 :IIII O 8IIII H [D 1.: lir-IIOII (.0 TABLE III (continued) 0 0 0 0 WWWWWWWWWWWWWWWWWWWWWWW —q-q:4:4:q:q:qjqjq:4:q:4-4-4—0-q-q-q—q-q-4-q-q O O O C I O\O\O\O\O\O\O\O\O\O\O\O\O\O\O\O\O\O\O\O\O\O\O\ c>c>c>c>E>c>Eg 000000 1237 1310 1480 1786 1893 1383 1577 1407 2111 1007 1560 1490 1553 1213 1626 1359 1771 1553 1650 1698 I-alII—ijllgllllallllllllll ND) C IIIIIIIOEhI ON 0 O 43 1.53 3.61 3-99 4.33 4.29 5.33 3.49 4.13 4.25 4.63 4.89 TABLE IV TRICKLING FILTER N0. 4 INFLUENT FEED RATE EFFLUENT DATE ins/L) (sal/yd3 (ms/L) (1956) BOD CIANIDE COPPER per day) BOD CYANIDE COPPER Oct. 15 - 0.00 0.00 1189 - - - 16 - 0.00 0.00 1844 - - - 17 137 0.00 0.00 1723 23 0.00 - 18 - 0.00 0.00 1577 - - - 19 0.00 0.00 1067 - - - 2O - O .OO O .00 1990 - - - 21 134 0.01 0.01 1844 11 - 0.00 22 - 0.01 0.01 1577 - - - 23 - 0.01 0.01 1456 - - - 24 - 0.02 0.01 1504 - - 0.00 25 195 0.02 0.02 1653 24 - 0.00 26 - 0.03 0.02 1213 - - - 27 - 0.03 0.02 1480 - - - 28 174 0.04 0.03 1844 33 - - 29 - 0.04 0.03 1577 - - - 3O - 0.05 0.03 1601 - - - 31 195 0.06 0.04 1202 - - 0.02 NOv. 1 - 0.06 0.04 - - - - 2 - 0.08 0.05 1237 - - 0.03 3 - 0.09 0.06 2135 - - - 4 180 0.10 0.07 1553 55 - 0.04 5 - 0.12 0.08 2184 - - - 6 O 0.14 0.09 1893 - 0.00 0.04 7 147 0.18 0.12 1723 16 - - 8 - 0.21 0.14 1965 - - 0.06 9 - 0.26 0.17 1577 - - _ 10 216 0.31 0.20 1795 30 - 0.09 11 - 0.37 0.24 1456 - - - 12 - 0.44 0.29 1893 - 0.00 0.08 13 ' 0053 0036 1.116 "' " "' 14 - 0.63 0.41 1965 - - 0.12 15 108 0.76 0.50 1310 22 - 0.19 16 - 0.96 0.60 1407 - - - l7 " 1010 O 072 1286 - '- 18 1.32 0.86 - - - 19 - 1.32 0.86 1698 - - 0.14 20 137 1.56 1.02 1140 18 0.00 0.22 21 - 1.86 1.21 970 - - - 22 - 2.20 1.43 - - 0.51 23 2.62 1.71 825 - - - D800 24 25 % m w m H l-‘ O I O\ 8" 14:4: to TABLE IV (continued) SSSSSSSBB Nadmyrwwm 688588 000 00 Ongvfio \nm-F’memml-J O CO 1650 1237 1359 1723 M% 1140 1407 O f’ OIIIIII\.J1I 0 ID #5 0062 1.45 2% 3.57 2.29 ANALYTICAL METHODS 1+7 ANALYTICAL METHODS Routine daily analyses of biochemical oxygen demand (BOD) were performed following the methods outlined in Standard Methods (3) using the Alsterberg (sodium azide) modification. Three dilutions were made using dilution water seeded with 3 ml. of aged, settled sewage per liter. The results reported are the averages of all individual dilutions that showed a 40 to 90% depletion of initial dissolved oxygen. Several common methods based on titration and colorimetry are available for the analysis of cyanides. Many of these, however, are difficult to apply to the routine laboratory analysis of samples containing sewage and industrial wastes. Three of these methods (19) have been found to be the most effective on industrial wastes containing domestic sewage. Two of these: The benzidine-pyridine method of Aldridge (1, 2) as modified by Nusbaum and Skupeko (21) and the pyridine-pyrazolone method of Epstein (15), while satisfactory, require fresh reagents daily to insure reliable results. Since only occasional determinations were to be made, these methods were not seriously considered. The modified Leibig titration using the p-dimethyl—amino benzalrhodanine indicator of Ryan and Culshaw (27) and outlined by Ruchhoft (26) was decided upon as being the most adaptable to this project. This method has been established by Serfass (28) to be preferable to the colorimetric techniques in the anticipated range of 1 mg/L or greater. The titration was preceded by the reflux distillation technique of Serfass. This method of isolation has been found to yield high recoveries Of HCN on simple and.most complex cyanides. Sewage and river water samples containing low concentrations of interfering compounds have consistently yielded cyanide recoveries of 95% using the reflux distillation for isolation. Some complex salts including those of cOpper require a second hour of distillation for their recovery (19). 48 Another isolation procedure, Kruse and Mellon (17), is available for separation of the cyanides from certain organic compounds which can destroy the cyanides during distillation. This technique utilizes solvent extraction with 2,2,H-trimethylpentane (iso—pentane), hexane, or chloroform (preference in the order named). It has been very successful in removing organic material without lowering cyanide recovery. This extraction technique was not employed in.this research since the required analyses were to be made on stock solutions containing no organic matter and on trickling filter effluents which ultimately proved to be low in organic compounds. The possibility Of interference with cyanide recovery from.the low concentration of organic matter present in the trickling filter effluents was neglected since this data was to be used only as a measure of filter performance. . Prior data of Dane (7) and Ludzack (19) have established the normal range of cyanide to be expected in the filter effluent under comparable conditions. The copper determinations were made using the well established colorimetric method as outlined in Standard Methods (3) and Procedures for Analyzing Metal Finishing Wastes (22). The sample is treated 'with hot concentrated acids to remove organic matter and the cOpper is extracted with mercaptobenzothiazole and chloroform. Sodium diethyl dithiocarbamate is added to the chloroform extract to produce a strongly colored orange-yellow complex which is measured on a colorimeter or filter photometer. Figure IX shows that this method yields excellent results in.the absence of bismuth, mercury, silver, and lead. There is at least a 98% recovery with a standard deviation of plus or minus 1 to h% in the presence of small concentrations of other metallic ions. The liquid samples for cOpper analysis were treated as above: however, the sludge required additional pretreatment. Sludge samples were dewatered in a suction filter, and then treated with acid as above. A second sample was weighed, dried to constant weight in oven, and reweighed to provide a correction for entrained liquid. Liquid removed in the filter was analyzed for COpper and a true dry sludge analysis calculated. 7'" TABLE V COPPER CALIBRATION DATA Sample No. mg of Cu per liter Optical Density 1 0.0110 0.260 2 0.0140 0.255 3 0.0160 0.390 4 0.0166 0.360 5 0.0221 0.395 6 0.0260 0.470 7 0.0276 0.480 8 0.0310 0.510 9 0.0442 0.610 10 0.0450 0.630 11 0.0552 0.715 12 0.0650 0.790 13 0.0662 0.810 14 0.0780 0.900 15 0.0828 0.950 16 0.0840 0.950 17 0.1100 1.060 18 0.1104 1.150 19 0.1200 1.240 20 0.1214 1.250 21 0.1370 1.380 22 0.1546 1.500 23 0.1656 1.650