WATER POLLUTION CONTROL RESEARCH SERIES ORD 17O ', Of- K AOb/ 7O "DEVELOPMENT OF A PILOT PLAKT TO DEMONSTRATE REMOVAL OF CARBONACEOUS, NITROGENOUS AND PHOSPHORUS MATERIALS FROM ANAEROBIC DIGESTER SUPERNATANT AND RELATED PROCESS STREAMS" U.S. DEPARTMENT OF THE INTERIOR • FEDERAL WATER QUALITY ADMINISTRATION ------- WATER POLLUTION CONTROL RESEARCH SERIES The Water Pollution Control Research Reports described the results and progress in the control and abatement of pollution of our Nation’s waters. They provide a central source of information on the research, development, and demonstration activities of the Federal Water Quality Administration, Department of the Interior, through in-house research and grants and contracts with Federal, State, and local agencies, research institutions, and industrial organizations. Water Pollution Control Research Reports will be distributed to requesters as supplies permit. Requests should be sent to the Planning and Resources Office, Office of Research and Development, Federal Water Quality Adminis- tration, Department of the Interior, Washington, 0. C. 20242. ------- DEVELOPMENT OF A PILOT PLANT TO DEMONSTRATE REMOVAL OF CARBONACEOUS. NITROGENOUS, AND PHOSPHORUS MATERIALS FROM ANAEROBIC DIGESTER SUPERNATANT AND RELATED PROCESS STREAMS by George E. Bennett Environmental Engineering Department Centra] Engineering Laboratories FMC Corporation Santa Clara, California 95052 for the FEDERAL WATER QUALITY ADMINISTRATION DEPARTMENT OF THE INTERIOR Program #17010 FKA Contract #14-12-414 FWQA Project Officer, E. F. Barth Advanced Waste Treatment Research Laboratory Cincinnati, Ohio May, 1970 For sale by the Superintendent of Documents, tT.8. Government Printing Office Washington, D.C. 20402 - Price *1 ------- FWQA Review Notice This report has been reviewed by the Federal Water Quality Administration and approved for publication. Approval does not signify that the contents neces- sarily reflect the views and policies of the Federal Water Quality Administration, nor does mention of trade names or comercial products constitute en- dorsement or recommendation for use. 1 ------- ABSTRACT Digester supernatarit contains high concentrations of nitrogen and phosphorus. Also, poor quality supernatant discharged from an anaerobic digester can have an adverse effect on the overall efficiency of a wastewater treatment plant. Under F QA sponsorsnip, the Central Engineering Laboratories of the FMC Corp- oration undertook to build and demonstrate the operation of a unique, trailer- mounted, and completely self-contained pilot plant. The pilot plant is designed to investigate the improvement of digester supernatant quality, with particular emphasis on the removal of nitrogen and phosphorus. The pilot plant treatment sequence consists of carbon dioxide removal via air-stripping, lime precipita- tion of phosphorus and carbonaceous particulate matter, and removal of nitrogen by packed-tower ammonia-stripping. The pilot plant was operated over a two-month period at a trickling filter plant where two-stage anaerobic digestion is practiced. The pilot plant oper- ated in a reliable and consistent fashion with respect to both tkle mechanical performance and the process data obtained. A wide range of operating condit- ions was investigated in a convenient and effective manner. It was found that 80—95% of supernatant phosphorus could be removed at a lime dosage equal to 50 pounds of hydrated lime per pound of phosphorus removed. Average ammonia-nitrogen removal was 82%, achieved at an air flow rate equal to 83,000 cubic feet of air per pound of 1H 3 -N removed. Normal lime precipitation removed about one-half of tne supernatant TOG, COD, and Organic Nitrogen. The average decrease in suspended solids was 64%. This report is submitted in fulfillment of Contract No. 14-12-414 (Program No. 17010 FKA) between the Federal Water Quality Administration and the Central Engineering Laboratories of FMC Corporation. Key Words: Sludge Treatment, Supernatant Nutrient Removal, Phosphorus Removal, Nitrogen Removal, Ammonia Stripping. 111 ------- SECTION C 0 N T E N T S P AGE CONCLUSIONS INTRODUCTION . BACKGROUND ANU OBJECTIVES . . . . DESIGN AND CONSTRUCTION OF PILOT PLANT OPERATION OF PILOT PLANT . . . . FIELUTESTSITE . . .. . RESULTS OF FIELD TESTING . . . . DISCUSSION . . . . . . . . . . . . . ECONOMIC CONSIDERATIONS . . . . . ACKNOWLEDG 1ENTS . . . . . . . . REFERENCES . . . . . . . . . . . . . APPENDIX • . I I S • • S S • S • S S I S S I S S S S • I I • I I S S S I S • I • I • I • S I S S S S I S S • S S I S S S I S S • • I S • S I I S • • S S S S I S S S S S S S • I S S S S S • S S S • I S S I S S S S S S I. II . III. ‘VS V. VI. VII . VIII. Ix. XI XI. XIII 1 3 5 7 11 15 19 47 57 59 61 63 V ------- LIST OF FIGURES TITLE 8 8 9 9 FIGURE NO . PAGE Figure 1 Supernatant Beneficiation Pilot Plant TreatmentSequence. . . . . . . . . . . . •.. 6 Fiqure2 ReactorVessel . . ... . •øê*S••S• . . Figure 3 Reactor Vessel Air—Diffusion lanifold . . . . . . Figure 4 Rear View of Ammonia—Stripping Columns . . . . . . . Figure 5 Two—Inch Intalox Saddles in No. 1 Stripping Column. Figure 6 Digester Supernatant Beneficiation Pilot Plant Readyforlransport •0••S• ....... .12 Figure 7 Ammonia-Stripping Column Flow Pattern . . . . . . . . . 14 Figure 8 Titration Curves for Irvington WTP Digester S upernatant . . . . . . . . . . . * . . . . . . . 17 Figure 9 Carbon Dioxide Stripping at Varying Air Rates . . . . . 22 Figure 10 Reaction Tank During Normal Carbon Dioxide Stripping (Air @ 550 cfm) . . . . . . . . . . . . 23 Figure 11 Reaction Tank During a High Air Flow Carbon Dioxide Stripping (Air @ 700 cfm) . . . . . . . . 23 Figure 12 Waste Sludge Disposal Area . . . . . . . . . . . . . . 36 Figure 13 Ammonia-Nitrogen Removal vs A/W Ratio . . . . . . . . . 44 Figure 14 Recomended Facilities for Beneficiation of Irvington WTP Digester Supernatant . . . . . . . . 52 Figure 15 Supernatant Benefi ci ati on Facilities For 50 MGD Plant* . . . . . . . . . . . . . . . . . 54 vii ------- TABLE NUMBER LIST OF TABLES TITLE PAGE Table I Table II Table III Table IV Table V Table VI Table VII Table VIII Table IX Table X Table XI Table XII Table XIII Table XIV Table XV Table XVI • • • • • • 18 • • • . • 20 • 25 • 26 • 28 • 29 • 30 • 32 • • • • • 33 • . • 35 • • • 37 • • . • 39 • 41 • 45 • 46 I • • I • • 16 Laboratory Characterization of Digester Supernatant, Irvington, W.T.P. • • . Characteristic of Irvington WTP Supernatant Composition of Digester Supernatant Liquors Effect of Carbon Dioxide Stripping Time On Lime Dosage • • • ••. • • • • • • • • • • Summary of Operating Temperatures • • • • • • • • Removal of Total Phosphorus • • • • • • • • • • • Removal of Total Orthophosphate . • • • • • • • Removal of Soluble Orthophosphate • • • • • • • • Removal of Suspended Solids • • • • • • • • • • • Effectiveness of Lime Treatment and Settling Sludge Production • • • • • • • • • • • • • Effect of Supernatant Strength on Lime Precipitation Performance* • • • • • • • • Effect of Reactor Vessel Settling Period • • Ammonia Nitrogen Removal Summary . • • . . • • . . Ammonia-Stripping Requirements • • • • • • • • • • Ammonia Stripping Temperature Summary . • • • • • • ix ------- SECTION I CONCLUSIONS 1. Pilot plant operation at the Irvington WTP demonstrated that the trailer- mounted unit can be conveniently and effectively used to investigate supernatant beneficiation. It was possible to use tne pilot plant exactly as intended without interfering with the normal operation of the Irvington WTP. A wide range of operating conditions and situations were investigated without difficulty. The pilot plant operated in a reliable and consistent manner with respect to both mechanical performance and the process data obtained. 2. Overall total phosphorus removal of at least 80% can be achieved at pH values of 10.8 or greater. As the pH is increased above 10.8, the degree of phosphorus removal also increases. At pH 11.4, 86% of tne total phosphorus and 95% of the orthophosphate will be removed. 3. Supernatant beneficiation is a very economical means of phosphorus removal, on the basis of cost per pound of phosphorus removed. The portion of phosphorus which becomes concentrated in digester supernatant can be re- moved at operating and capital equipment costs which are 8-9% and 93% lower, respectively, than the operating and capital equipment costs for removal of phosphorus occurring in normal wastewater concentrations. 1 ------- 4. Amonia-nitrogen removal of 80-95% can be achieved at pH values in the 11.2 — 11.4 range. The stripping air requirement for 85% ammonia removal at pFI 11.4 is 83,000 cubic feet per pound of amonia-nitrogen removed. 5. On the basis of cost per pound of nitrogen removed, amonia—stripping be- comes more economical as the concentration of ammonia increases. Thus the nitrogen which becomes concentrated in the digester supernatant (as amonia) can be removed at a relatively low cost. 6. Although the supernatant beneficiation process is oriented mainly toward nutrient removal, it also produces a major incidental improvement in over- all supernatant quality. Operation at Irvington resulted in removal of 64% of the initial suspended solids, and roughly one-half of the initial TOC, COD, and organic nitrogen. 7. No scaling of tank or stripping column surfaces was encountered during the Irvington testing, wnich involved the total use of more than 2300 pounds of lime in processing over 50,000 gallons of supernatant. 8. The digester supernatant produced at the Irvington WTP, a trickling filter plant, has considerably higher concentrations of ammonia nitrogen, phos- phorus, suspended solids, and total organic carbon than supernatant pro- duced at activated sludge plants. The stronger supernatant was readily treatable, however, and the trailer-mounted pilot plant performed well and met all effluent criteria. 2 ------- SECTION II INTRODUCTION Rapid eutrophication of lakes and waterways is a major environmental problem facing our nation today. Nitrogen and phosphorus are key factors in the eutrophication process. Conventional wastewater treatment is oriented toward the stabilization of organic carbonaceous matter and is relatively ineffective in removing nitrogen and phosphorus from wastewater. The problem of controlling and minimizing the concentration of nutrients in wastewater treatment plant effluents is, therefore, receiving much current attention. Most of the nutrient removal schemes currently proposed or under investigation involve the processing of the entire volume of treatment plant throuqh-put. This is necessary in order to achieve a high level of overall nutrient removal. it is conceivable, however, that situations presently exist or may arise where only partial removal of nitrogen and phosphorus is required, or can be toler- ated. Under these conditions, significant economies are available if nutrients are removed at a point in the treatment process where they occur in relatively high concentrations. Anaerobic digester supernatants (and similar process streams such as centrate liquors, vacuum filter filtrate, etc.) contain particularly high concentration of nitrogen and phosphorus. Supernatant also contains a considerable amount of carbonaceous organic material, sufficient in many cases to upset or reduce the efficiency of aerobic treatment processes. Supernatant from anaerobic digesters can therefore reduce or limit treatment plant performance. An economical 3 ------- process which could remove nitrogen, phosphorus, and carbonaceous material from digester supernatant could be an effective means of improving the operational efficiency of wastewater treatment plants, and at the same time reduce the eutrophication potential of the treated effluents. 4 ------- SECTION III BACKGROUND AND OBJECTIVES The objectives of this project were: (1) to develop a process for improving the quality of digester supernatant, (2) to produce a portable pilot plant suitable for demonstrating and investigating digester supernatant beneficiation, and (3) to demonstrate the satisfactory operation of the pilot plant under realistic field conditions. These objectives were successfully met. The project was done in three phases. Phase One work involved laboratory in- vestigations to select and verify a feasible and reliable supernatant treatment process. Phase Two consisted of the design and construction of a trailer- mounted, self—contained pilot plant. Phase Three consisted of field operation at a municipal wastewater treatment plant to demonstrate the applicability of both the treatment process and the pibt plant to the investigation of digester supernatant beneficiation. The Phase One work has been described in detail in a previous report (1). Briefly, it involved the laboratory—scale application of various unit processes to the treatment of digester supernatants from two municipal wastewater treat— ment plants. It was concluded that chemical precipitation (using lime) followed by packed-tower air—stripping would constitute a practical and economical means of removing nutrient materials and reducing the amount of organic carbonaceous matter in anaerobic digester supernatants. This report describes and summarizes the Phase Two and Phase Three work. 5 ------- FIGURE I SUPERNATANT BENEFICIATION PILOT PLANT TREATMENT SEQUENCE RETURN TO MAIN WTP THROUGH-PUT STREAM DIGE STER SUPER NATANT SLURRY OF SLAI LIME NI4 3 -N RELEASED TO ATMOSPHERE TO WASTE OR RE CA LC I NI NC AND REUSE NUTRIENT-FREE SUPERNATANT LIME COMPRESSED SLUDGE AIR ------- SECTION IV DESIGN AND CONSTRUCTION OF PILOT PLANT Following successful completion of the Phase One work, a trailer—mounted pilot plant was designed and built. Figure 1 indicates schematically the pilot plant treatment sequence. Pilot plant operation is a combination of batch and continuous-flow treatment. Car- box dioxide stripping and chemical precipitation are done on a batch basis, while ammonia—stripping is accomplished on a flow—through basis. The key equip- ment components are the Reactor Vessel and the Stripping Columns. Reactor Vessel : The treatment sequence is set up so that a single 2000-gallon tank, called the Reactor Vessel (Figure 2), can be used for stripping carbon dioxide and also for flash-mixing, flocculation, and settling. An air-diffusion manifold utilizing 33 Chicago Pump Company Uiscfusers is used for stripping the carbon dioxide from fresh digester supernatant, as indicated by Figure 3. A lift mechanism is provided so that the manifold can be raised above the oper- ating liquid level (i.e., out of the water) as needed. The Reactor Vessel has a conically-shaped lower portion to facilitate the efficient removal of settled lime sludge. Sampling ports are located at various tank levels; samples may also be drawn from the bottom of the settling cone. 7 ------- FIGURE 2 REACTOR VESSEL FIGURE 3 REACTOR VESSEL Al R DI FFUSIO1 MAUI FOLD C’ I if JJ ’ 8 ------- FIGURE 4 REAR VIEW OF AMMON IA—STRIPPING COLUt1IIS FIGURE 5 TWO-INCH INTALOX SADDLES IN HO. 1 STRIPPING COLUMN. NOTE REACTOR VESSEL EFFLUENT DISTRIBUTOR PIPE. I A. r 1 9 ------- Counter—Flow Stripping Columns : Ammonia—strippinq is clone in two 3,5 foot diameter stripping columns (Fiqure 4). The columns can be o!,erated in series or can be used separately. Each stripping colunn is 12 feet hinh overall and contains 80 cubic feet of 2-inch plastic “Intalox ” saddles (Figure ). The aninonia—stripping facilities are designed to permit a maximum degree of operational versatility. Air—to—water (A/w) ratios of from 130 to 900 cubic feet per gallon can be provided. A steam generator has been provided so that the stripping—air temperature can be raised by steam injection, Appropriate sampling ports are provided so that composite samples of Column #1 influent, Column #1 effluent (which is also Column #2 influent), and Column #2 effluent can be conveniently collected. Trailer : All of the pilot plant components, including a small control buildinq and an auxiliary 1250-gallon settling tank, are located on a sinnle axle flat- bed trailer (Figure 6). All necessary auxiliary equipment (pumps, pipinq, electrical switchgear, etc.) required for pilot plant operation is included as an integral part of the trailer. A functional piping diagram indicating the relative positions of the various components is also included in the Appendix. A complete list of the various equipment components is included in the Appendix. 10 ------- SECTION V OPERATION OF PILOT PLANT The pilot plant is designed to process 2,000 gallons of supernatant at a time. The normal treatnent sequence beqins by drawing or pumping 2,000 gallons of the test supernatant into trie Reactor Vessel. After the Reactor Vessel is filled, the air is turned on briefly (1-3 minutes) to thoroughly mix tue test supernatant. A sample of the test supernatant is then drawn from a sampling port located at mid-depth in the tank. After a re- presentative sample of test supernatant is obtained, aeration is resumed. Aeration of the supernatant causes carbon dioxide to be stripped from the supernatant. Aeration in the Reactor Vessel is continued until the bulk of tue carbon dioxide is removed and an equilibrurn pH has been reached. After the excess carbon dioxide has been stripped out, phosphorus is removed by chemical precipitation. This is accomplished by adding slaked lime (in slurry form), flocculating for about 15 minutes through use of the Reactor Vessel aeration system, and allowing the precipitated solids to settle in the quiescent Reactor Vessel. Good removal oF phosphorus can be achieved at pH 10.0 or even lower. However, higher pH values are required for the subsequent ammonia- stripping operation, described below. Therefore, an excess of lime is used in the phosphorus precipitation portion of the pilot plant process. 11 ------- FIGURE 6 DIGESTER SUPERNATANT BENEFICIATION PILOT PLANT READY FOR TRANSPORT -a ------- After the precipitated solids have settled, the sludge is drawn off. The sludge can be held for an additional 1—2 hour period in the pilot plant auxiliary settling/thickening tank. This practice is convenient to the general operating routine and also permits the pilot plant operator to observe the degree of “secondary” compaction and the decrease in sludge volume associated with the additional settling time. After the supernatant phosphorus has been precipitated, ammonia-nitrogen is removed by countercurrent flow air-stripping in the packed columns. Liquid flow rates of 5-15 gpm are used, with air flow at 2000 - 4500 cfm. The two identical stripping towers are noramlly operated in series, as indicated by Figure 7. The Reactor Vessel liquid flows downward through each of the two stripping towers in series. At the same time, air is simultaneously blown upwards through each column, in the opposite direction. Ammonia—stripping is the final step in the pilot plant treatment sequence. The Column #2 effluent is, therefore, also the pilot plant final effluent. 13 ------- FIGURE 7 AMMONJA-STRJPP NG COLUMN FLOW PATTERN TOWER NO. 2 TOWER NO. 1 PHOSPHORUS A ND AMMONIA FREE EFFLUENT PHOSPHORUS-FREE REACTOR VESSEL EFFLUENT 14 ------- SECTION VI FIELD TEST SITE Field testing and operation of the trailer-mounted pilot plant took place at the Irvington Wastewater Treatment Plant near Fremont, California. This plant is part of the Union Sanitary District pollution control system and serves a portion of the City of Fremont. The Irvington WTP is a bio-filter plant designed for 10.5 1GD flow. During the pilot plant test period, it was receiving about 50% of the design flow. The anaerobic digestion facilities are well operated. There have been no significant digester problems at this plant. Sludge is pumped to the digester at 30—minute intervals, with the pumping period controlled by density meters. lormally, 15,000—20,000 gallons of sludge are pumped to the two—stage digester system per day. Supernatant is displaced from the secondary digester and is returned to the plant headworks. The digester gas contains 34—36% carbon dioxide, pH is in the 7.0 — 7.3 range, gas production is good, and volatile acids are consistently below 150 mg/liter. Treatment of the Irvington supernatant by the pilot plant process was simulated on a bench—top scale at the FMC Laboratories. The results are summarized in Table I and Figure 8. It was observed that nitrogen and phosphorus were present in relatively high concentrations and that the particulate solids con- tent of the supernatant was considerably higher than had been encountered with the two supernatant used during the Phase One work. It was apparent that operation at the Irvington plant would provide a challenging situation for demonstrating the applicability of the pilot plant process. 15 ------- TABLE I LABORATORY CHMACTERIZATION OF DIGESTER SUPERt4ATANT IRVINGTOU, W.T.P. Untreated Supernatant Supernatant Decant Sample* After Lime Treatment 7.1 10.7 Total Solids 4985 2753 Total Volatile Solids 3330 1821 Suspended Solids 2905 1190 Volatile Suspended Solids 2530 3U COD 5407 2919 Total Carbon 3075 1214 Total Organic Carbon 1624 914 Ortho - P0 4 (as P) 91 5.9 Total Phosphate (as P) 141 37 NH3—Nitrogen (as N) 818 726*** Organic Nitrogen (as N) 282 176 Calcium 156 ** Magnesium 48 ** * All values except pH are in mg/liter ** Not Determined Supernatant not air stripped after lime treatment 16 ------- FIGURE 8 TITRATION CURVES FOR IRVINGTON WTP DIGESTER SUPERNATANT AFTER CO 2 REMOVAL t3Y AIR STRIPPING p -J CD (J) L .J LL = 12.0 11.0 10. 9.0 8.0 7.0 / - - - -0 - --0 BEFORE CO 2 RE 1OVAL 0 .5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 LIME DOSAGE ( GRAMS CaO PER LITER) ------- TABLE II CHARACTERISTICS OF IRVINGTON WTP SUPERNATANT MAXIMUM VALUE MINIMUM VALUES OR CONCENTRATION OR CONCENTRATION (mg/liter) (mg/liter) ANALYSIS NUMBER OF SAMPLES ANALYZED AVERAGE VALUE OR CONCENTRATION (mg/i i ter) - TEMPERATURE 18 88°F 82°F 85°F pH 18 7.42 7.10 7.26 SUSPENDED SOLIDS 18 3,200 1,640 2,205 (. 1,66 4,545 2,930 VOLATILE SUS— PENDED SOLIDS 18 2,380 1,120 TOTAL SOLIDS 18 5,300 4,355 5 V0 Thhi 18 3,500 2,700 TOTAL CARBON 18 3,030 2,420 2,719 TOTAL ORGANIC CARBON 18 1 25 ,6 828 1,242 TOTAL —P0 4 (as P) 18 154 135 143 66 ORTHO-P0 4 (as P) 18 73 62 AMMONIA—NITROGEN 18 925 794 — 853 ORGANIC NITROGEN 9 381 260 . ALKALINITY 18 3,962 3,637 3,780 87 VOLATILE ACIDS 18 132 46 CO.D. HARDNESS 9 4,848 4,309 4,565 - 9 302 239 264 CALCIUM MAGNESIUM 9 9 131 47 100 41 I 116 1 44 ------- SECTION VII RESULTS OF FIELD TESTING A total of twenty-three complete or partial operating runs were made at the field test site (Irvin ton WTP). lechanical operation and performance of the pilot plant met all design expectations. The treatment process liketiise oper- ated as anticipated. In several respects, pilot plant results were better than the laboratory results achieved during t ie Phase One work. I RVINGTOI1 SUPERNATANT The Irvington supernatant produced during the testing period was consistent in quality, as indicated by Table Ii. In general, it was considerably stronger than the supernatants studied during the Phase One work, which had been quite similar to the supernatant values reported by 1asse1li (2). Table III sum- marizes the Masselli data and the Phase One supernatants. The Irvington supernatant contained roughly twice as much phosphorus and ammonia as either the Phase One supernatants or the Masselli supernatants. As noted previously, all control and operating parameters indicate that the anaerobic digestion system at the Irvington plant operates normally and efficiently. It is believed that the higher—than—usual concentrations of nutrients in the Irvington supernatant reflect efficient digester loading. This may be a normal condition at bio—filter plants (the Phase One plants were both activated sludge plants) or it may be a result of the up-to-date sludge handling techniques and equipment used at the Irvington plant. 19 ------- TABLE III COMPOSITION OF DIGESTER SUPERNATANT LIQUORS ANALYSIS PHASE ONE SUPERNATANTS SUPERNATANT VALU MILPITAS TREATMENT PLANT* SAN JOSE TREATMENT PLANT LAGOON * REPORTED BY MASSELLI (2) pH 7.04 7.8 7.3 SUSPENDED SOLIDS 383 143 --- VOLATILE SUSPENDED SOLIDS 299 118 ——- TOTAL SOLIDS 1,475 2,160 3,260 TOTAL VOLATILE SOLIDS 814 983 1,541 TOTAL CARBON 740 930 --- TOTAL ORGANIC CARBON 443 320 --- TOTAL PHOSPHATE (as P) 63 87 56 SOLUTION PHASE ORTHO-P0 4 (as P) 45 74 --- NH 3 NITROGEN (as N) 253 559 402 ORGANIC NITROGEN (as N) 53 91 ——— ALKALINITY (as CaCO 3 ) 1,349 1,434 1,675 HARDNESS (as CaCO 3 ) 322 250 890 COD 1,384 1,310 --- *A11 values except pH are in mg/liter. 20 ------- BATCH AIR—STRIPPING OF CARBON DIOXIDE Field results confirmed the preliminary laboratory indications that initial air- stripping of carbon dioxide is an important step in the supernatant beneficia- tion process. Reasonably complete removal of carbon dioxide produced a one- unit increase in supernatant ph (from 7.2 to pH 8.2). The lime requirement was increased by as much as 25% when carbon dioxide was only partially stripped out prior to chemical treatment (Figure 8). Satisfactory removal of carbon dioxide was achieved by batch stripping for 60 minutes at an air flow of 550 cfm. At this A/W* ratio (16.5 cubic feet per gallon), the highest practicable pH (8.1 to 8.2) was consistently achieved. Figure 9 indicates the effect of batch air- stripping on the pH of the supernatant. It was possible to raise the ph more rapidly if a higher air flow rate (800 cfm) was used. The pH could be raised to 8.2 within 30 minutes by using a higher air flow rate, 800 cfm. However, this resulted in rapid and excessive foaming, as Figure 11 indicates. Figures 10 and 11 illustrate the degree of foaming associated with the normal air flow rate as opposed to the higher flow rate. The A/W ratio when operating at 550 cfm was 16.5 cubic feet per gallon. This was considerably in excess of the 3 cubic feet per gallon A/W ratio anticipated on the basis of the Phase One work. This discrepancy is probably due to the fact that it is difficult to accurately simulate carbon dixoide stripping on a small—scale laboratory basis. In any event, the air requirement for carbon * Air—to—Water, cubic feet per gallon. 21 ------- FIGURE 9 CARBON DIOXIDE STRIPPING AT VARYING AIR RATES HIGH AIR 800 cfr L..._._ NORMAL (WERATTNG RANGE 550 cfr OF AIR 400 cfm 60 C02 STRIPPING TIME (MINuTEs) 0 ‘V 0 = C- 8.4 8,2 8.0 7.8 7.6 7.4 7.2 7.0 LOW AIR 10 20 30 40 50 22 ------- .. __ 0- FIGURE 10 REACTION TANK DURING NORMAL CARBON DIOXIDE STRIPPING (AIR @ 550 CFM) FIGURE 11 REACTION TANK DURING A HIGH AIR FLOW CARBOU DIOXIDE STRIPPING (AIR @ 700 CFM) 23 ------- dioxide stripping was well within the capabilities of the pilot plant blower C 550 cfm required versus 4500 cfm blower capacity). Table IV indicates the process lime requirements at the Irvlngton plant in relation to carbon dioxide stripping. At an air flow rate of 550 cfm, reducin the air stripping timeby 67-75% increased the required lime dosage by 25%. Operating temperatures during field testing are sunriarized in Table V. Ambien air temperatures were in the 50-80°F range. The average air temperature was 62°F, and there was very little temperature decrease during the normal one—hou carbon dioxide stripping interval. No significant change in alkalinity occurred during carbon dioxide stripping. TOC data relative to the batch stripping operation were erratic, but no signi- ficant loss of volatile material was indicated. On the average, there was a 5% decrease in total carbon during batch stripping. As expected, there was no reduction of the NH3-N concentration as carbon dioxide was removed. Carbon dioxide stripping could be done more efficiently if foaming could be controlled by water spray or an anti—foamant additive. The decrease in stripping time would more than offset the increase in the air flow rate, pro- ducing a lower resultant A/W ratio. This could be a significant factor in a flow—through (rather than batch) system, since the required stripping vessel volume could be reduced by 50%. 24 ------- TABLE IV EFFECT OF CARBON DIOXIDE STRIPPING TIME ON LIME DOSAGE Irifluent SuDernatant pH Carbon Dioxide Stripping Time (Minutes) Carbon Dioxide Stripped Supernatant pH Lime Dose (mg/liter) pH After Lime Addition A/W Ratio (Cubic feet! gallon) 7.1 7.3 7.2 7.2 7.2 7.2 7.3 7.3 60 45 30 30 15 15 15 8.1 8.2 8.1 8.U 8.0 7.9 7.9 7.7 6000 6000 6000 6600 6000 4500 7500 11.4 11.2 10.8 11.1 10.1 11.3 16.5 12.4 8.3 8.3 4.1 4.1 ------- TABLE V SUMMARY OF OPERATING TEMPERATURES Maximum Minimum Average Sample Temperature* Temperature* Temperature* Influent Supernatant 88 82 85 Supernatant After CO 2 Stripping 88 73 83 Reactor Vessel Effluent 86 76 82 Column #1 Effluent 79 61 68 Column #2 Effluent 77 59 66 (Process Effluent) Ambient Air Temperature 80 51 62 Compressed Air Temperature 96 73 34 Stripping Tower Air Temperature 76 53 65 * All temperatures in 0 F. 26 ------- LIME PRECIPITATION TREATMENT The pilot plant chemical precipitation step has two main oojectives. The first is to remove as much phosphorus as possible; the second is to produce a Reactor Vessel effluent with a high pH value, whicii is required for subsequent ammonia— stripping. Lime is the most suitable coagulant chemical. It is effective in precipitating phosphorus,and also raises the 2H. Under normal operating con- ditions (i.e., with carbon dioxide strioped out prior to lime treatment), 6,000 mg/liter of slaked lime produced a Reactor Vessel pH in the 10.8 - 11.4 range. Lime precipitation produced total phosphorus removals of 80% or more at pH values of 10.8 or greater. The average total phosphorus removal under normal* operating conditions was 84%. The deqree of total pnospnorus removal gradually increased as the pH was increased above the 10,8 pH value. The maximum Total P removal under normal operating conditions was 8i % and occurred at a ph value of 11.4. All of the total phosphorus removal results are presented in Table VI. As expected, orthophospriate was readil.y removed (as shown y Tables VII and VIII), particularly the soluble orthophospnate. Soluble ortho hosphate re- movals of 90—95% were consistently achieved when the pH was in the 10.3 — 11,4 range. As with the total phosphorus, increased removals of orthophosphate correlated with higher pH values. At pH 11.4, % removal of orthophosphate was achieved. * See Summary of Lime Precioitation Field Test Conditions,” Item A—l in Aopendi x 27 ------- TABLE VI REMOVAL OF TOTAL PHOSPHORUS Test No. Influent Supernatant pH Influent Supernatant Concentration (mg P/liter) Reactor Vessel pH after Lima Addition Reactor Vessel Effluent Concentration (mg P/liter) Percent Removal Pilot Plant Effluent nH Pilot Plant Effluent Concentration (mg P/liter) overall Process Percent Removal A. Tests Made Under Normal Operatino Conditlons* 16 20 18 19 3 4 5 7 8 17 2 7.1 7.2 7.3 7.3 7.3 7.4 7.3 7.2 7.3 7.3 7.3 145 144 143 143 139 140 142 141 141 149 135 10.8 10.8 11.2 11.2 11.4 11.4 11.4 11.4 11.4 11.4 11.7 26.2 25.0 22.7 21.9 21.8 19.8 18.8 18.4 20.5 21.3 20.5 82 83 84 85 84 86 87 87 85 86 85 10.5 10.4 10.8 10.7 11.3 11.3 11.2 11.2 11.1 11.3 11.8 28 26 26 23 23 23 21 20 24 22 23 81 82 83 84 84 84 85 86 83 85 83 AVERAGES FOR NORMAL RUNS: I 142 11.3 21.5 —__85 11.1 24 84 B. Tests Made Under Non—Normal Operatini Conditions* 12 14 6 15 9 10 11 13 1 7.3 7.2 7.2 7.3 7.3 7.3 7.3 7.2 7.4 142 135 138 152 149 140 143 90 154 9.7 10.7 10.8 11.2 11.4 11.5 11.6 11.8 12.3 27.3 26.0 28.1 21.0 20.3 18.7 18.4 12.2 20.9 81 81 80 86 87 86 87 86 87 8.9 10.2 10.2 10.5 11.1 11.2 10.9 11.5 12.3 29 28 30 22 23 22 21 13 19 80 79 78 86 85 84 85 86 87 AVERAGES FOR NON-NORMAL RUNS: I 7. J 138 11.2 21.4 85 10.8 23 -I 83 C. Supplemental Tests * 21 7.1 148 22 7.2 145 23 7.2 11.2 11.0 ** 22.7 28.5 ** 85 80 ** ** 9.5 ** ** ** ** ** ** * Refer to Appendix for explanation of Normal, Non—Normal, and Supplemental Operatinp Conditions, Item A—3 ** Malysis not performed. 28 ------- TABLE VII REMOVAL OF TOTAL ORThOPHOSPHATE Test No. Influent Supernatant pH Influent Supernatant ConcentratIon (mg P/liter) Reactor Vessel pH After Lime Addition Reactor Vessel Effluent Concentration (mg P/liter) Percent Removal Pilot Plant Effluent pH Pilot Plant Effluent ConcentratIon (mo p/liter) Overall Process Percent Removal A. Tests Made Under Normal Operatina Conditlons* 16 20 18 19 3 4 5 7 8 17 2 7.1 7.2 7.3 7.3 7.3 7.4 7.3 7.2 7.3 7.3 7.3 -- ** ** ** 106 107 103 108 103 ** 107 10.8 10.8 11.2 11.2 11.4 11.4 11.4 11.4 11.4 11.4 11.7 ** ** ** 11 10 9 9 11 ** 11 * ** ** 90 91 91 92 89 ** 89 10.5 10.4 10.8 10.7 11.3 11.3 11.2 11.2 11.1 11.3 11.8 ** ** ** 12 11 11 10 14 ** 12 ** ** ** ** 89 89 89 91 87 ** 88 AVERAGES FOR NORMAL RUNS: 7.3 106 11.3 10 90 11.1 12 , 89 B. Tests Made Under Non—Normal Operating ConditlOnS* 12 14 6 15 9 10 11 13 1 7.3 7.2 7.2 7.3 7.3 7.3 7.3 7.2 7.4 ** CC 105 ** 111 105 CC CC 117 9.7 10.7 10.8 11.2 11.4 11.5 11.6 11.8 12.3 ** 17 10 10 10 84 91 90 92 8.9 10.2 10.2 10.5 11.1 11.2 10.9 11.5 12.3 C C CC 18 CC 12 12 CC CC 9 CC CC 83 CC 89 89 CC CC 93 AVERAGESFOR NON-NORMAL OPERATING CONDITIONS: 7.3 110 11.2 12 89 10.8 13 89 C. Supplemental Tests* . 21 22 23 7.! 7.2 7.2 CC CC 11.2 11.0 CC CC CC *C ** CC ** CC 95 CC ** CC CC CC C* CC * Refer to Appendix for explanation of Normals Non-Normal, and Suoplemental Operating Conditions, Item A—3 ** Analysis not performed. 29 ------- TARLE VIII REMOVAL OF SOLUOLE ORTHOPIIOSPHATO Test No. Influent Supernatant p 11 Influent Supernatant Concentration (rag P/liter) Reactor Vessel H After Lime Addition Reactor Vessel Effluent Concentration (rig P/liter) Percent Remeval Pilot Plant Effluent pH Pilot Plant Effluent Concentration ‘ 1fl9 P/liter) Overall Process Percent Rer’mval A. Tests M ade Under Normal Operating Conditi ons* 16 20 18 19 3 4 5 7 8 17 2 7.1 7.2 7.3 7.3 7.3 7.4 7.3 7.2 7.3 7.3 7.3 65 71 68 65 62 63 67 73 66 69 62 10.8 10.8 11.2 11.2 11.4 11.4 11.4 11.4 11.4 11.4 11.7 4.6 5.1 4.3 3.2 3.6 2.2 2.1 2.8 3.4 4.4 6.9 93 93 94 95 94 96 97 96 95 94 89 10.5 10.4 10.8 10.7 11.3 11.3 11.2 11.2 11.1 11.3 11.8 7 7 5 6 4 5 4 4 6 4 6 89 90 92 91 94 92 95 94 92 94 91 AVERAGES FO 8 NORMAL RUNS: 7.3 j 66 1L3 3.9 94 11.1 5 92 8. Tests M ade Under Non—Normal Operatlno Condltlons* 12 14 6 15 9 10 11 13 1 7.3 7.2 7.2 7.3 7.3 7.3 7.3 7.2 7.4 62 63 69 61 66 68 66 46 73 9.7 10.7 10.8 11.2 11.4 11.5 11.6 11.8 12.3 5.0 7.0 45 2.1 1.8 2.0 4.0 3.0 5.3 92 89 94 97 97 97 94 94 93 8.9 10.2 10.2 10.5 11.1 11.2 10.9 11.5 12.3 12 14 10 5 4 4 5 2 5 80 78 85 92 94 94 92 97 94 AVERAGES FOR NON-NOIOIAI. RUNS: 7.3 64 11.2 3.7 94 10.5 7 90 C. Supplemental Tests* 21 22 23 7.1 7.2 7.2 82 84 11.2 11.0 2.6 3.5 ** 97 96 ** “ 9.5 ** ** ** ** ** ** • Refer to Appendix for explanation of Normals Non-Normal end Supplemental Ooerating Conditions, Item V 3 ** Analysis not performed. 30 ------- On the basis of average removal efficiencies under normal operating conditions, 1.04 pounds of soluble orthophosphate phospnorus and 2.01 pounds of total phosphorus were removed per 100 pounds of slaked lime used. Data relative to suspended solids removal under various operatinq conditions are presented in Table IX. Average S.S. removal under normal operating condi- tions was 64%, from 2251 mg/liter to 796 mg/liter. There was a correlation be- tween Reactor Vessel pH (after liming) and suspended solids removal efficiency. When the p11 was raised above pH 10.8, the suspended solids removal could be correlated with the initial suspended solids concentration of the influent supernatant liquor. Higher suspended solids removal efficiencies generally coincided with higher initial supernatant suspended solids values. As Table IX indicates, no selective removal of either organic or inorganic material occurred during lime precipitation. The initial supernatant particulate matter was 75% volatile, and the unflocculated suspended solids remaining in suspension after lime treatment and settling was 76% volatile. Table X sumarizes the results of lime precipitation treatment. TOG and COD removals, as indicated by Table X, averaged 49% and 48%, respectively. TOG removal was fairly constant over the normal range of operatinrt conditions. The Reactor Vessel effluent contained only 33% as much total carbon as the initial input supernatant. About 5% of the total carbon decrease occurred during car- bon dioxide stripping. Total carbon removals were about 5% lower at non- normal pH values (i.e. pH values out of the 10.8 — 11.8 range). emova1 of total carbon closely paralleled total solids reduction, as is to be expected. 31 ------- TABLE IX REMOVAL OF SUSPENDED SOLIDS TEST NO. INFLUE14T SUPERNATANT REACTOR VESSEL PILOT PLONT EFFLUENT - OVERALL PROCESS PERCENT S.S. REMOVAL pH S.S. Conc. (mn/liter) Percent Volatile S.S. ni-I After Lime Mdition Effluent S.S. Conc. (r’c/liter) Percent S.S. Rerioval Percent Volatile S.S. oil S.S. Conc. (mg/liter) Percent Volatile s.s. A. Te sts Made U nder Bonsai Omeratino Conditions* 16 20 18 19 3 4 5 7 8 17 2 7.1 7.2 7.3 73 7.3 7.4 7.3 7.2 7.3 7.3 7.3 2240 2310 2160 2320 2740 2670 2560 2050 1660 2210 1840 76 76 74 75 77 75 75 77 68 79 76 10.8 10.8 11.2 11.2 11.4 11.4 11.4 11.4 11.4 11.4 11.7 920 1050 950 860 850 835 605 605 825 890 364 60 55 56 63 69 69 76 70 50 60 80 80 74 69 72 80 80 79 75 77 81 69 10.5 10.4 iu.e 10.7 11.3 11.3 11.2 11.2 11.1 11.3 11.3 850 905 865 745 735 715 765 615 1045 750 700 72 70 61 73 78 72 67 72 57 72 65 62 61 60 68 73 73 70 70 37 66 62 -AVERA DES FOR NOR 7.3 MAL RU3S: [ 2251 75 11.3 796 64 76 11.1 790 69 64 8. Tests Made Under Non—Mornal Ooeratina Conditions* 12 14. 6 15 9 10 11 13 1 7.3 7.2 7.2 7.3 7.3 7.3 7.3 7.2 7.4 2150 1790 2260 1930 3520 1640 2110 1010 3200 76 72 76 73 76 75 74 51 74 9.7 10.7 10.8 11.2 11.4 19.5 11.6 11.8 12.3 345 1000 300 800 750 600 402 317 580 84 42 65 59 79 70 81 69 82 63 80 73 75 76 77 71 63 62 8.9 10.2 13.2 10.5 11.1 11.2 10.9 11.5 12.3 330 670 720 605 785 686 562 442 415 63 67 61 73 68 59 65 66 63 86 61 68 69 78 61 73 55 87 AVERA DES Fl l NON 7.3 —NORMAL RUNS: 2172 72 11.2 610 70 71 10.8 568 65 71 C. Supplemental 21 7.1 22 7.2 23 7.2 Tests 2200 81 11.2 1010 54 72 ** 3775 78 11.0 1105 69 81 95 ** *4 *4 ** ** ** - ** *.* 4* *4 * Refer to Apoendix for exolenitlor of Normal • Non-Normal • and Suooletnental Operating Conditions, Item A-3 Analysis not cerforeed. 32 ------- ( ) * Tests done after the pre_plasned 20-test evaluation schedule was coopleted. TABLE EFFECTIVENESS OF LIME TREATMENT AND SETTLING TEST REACTOR REACTOR VESSEL VESSEL SETTLING pH AFTER TIME LIME (Mm.) ADDITION PERCENT PERCENT TOTAL SOLUBLE PHOSPHORUS ORTHO— REMOVAL P04 REMOVAL PERCENT TOTAL ORTHO— PD 4 REMOVAL PERCENT SUSPENDED SOLIDS REMOVAL PERCENT VOLATILE SUSPENDED SOLIDS REMOVAL PERCENT TOC REMOVAL PERCENT COD REMOVAL PERCENT PERCENT TOTAL ALKALINITY CARBON REMOVAL REMOVAL PERCENT PERCENT PERCENT PERCENT PERCENT HARDNESS CALCIUM MAGNESIUM TOTAL ORGANIC REMOVAL REMOVAL REMOVAL SOLIDS NITROGEN REMOVAL REMOVAL A. Tests Made Under Normal OperBtlOfl Conditions 16 20 18 19 3 4 5 7 8 17 2 60 60 60 60 60 60 60 60 60 60 60 10.8 10.8 11.2 11.2 11.4 11,4 11.4 11.4 11.4 11.4 11.7 81 89 82 90 83 92 34 91 84 94 84 92 85 95 86 94 83 92 85 94 83 91 ** - ** 89 89 89 91 87 88 62 61 60 68 73 73 70 70 37 66 62 4 64 67 69 72 74 74 71 47 69 61 43 39 36 58 69 39 62 61 43 48 41 49 41 50 50 * *-* ** 52 ** 65 56 62 68 12 71 11 71 69 69 71 62 68 67 70 57 77 61 73 66 68 57 40 49 53 54 * 40 12 70 10 30 .* ** ** ** Ca 26 85 87 88 89 Ca a. ** 90 ** 38 37 42 42 50 46 45 46 38 43 4 60 46 46 47 Ca ** ‘ 53 Ca AVERAGES FOR NORMAL RUNS 11.3 84 92 76 64 67 49 48 67 66 47 30 88 43 50 B. Tests Made Under Non-Nonmial Operating Conditions 12 14 6 15 9 10 11 13 1 60 60 60 60 60 120 90 60 60 9.7 10.7 10.8 11.2 11.4 11.5 11.6 11.8 12.3 80 79 lB 86 84 85 85 66 87 80 78 86 92 94 92 92 97 94 -- ** 83 89 -- ** “ 93 85 61 68 69 78 61 73 56 87 87 64 74 69 80 72 77 43 89 4 36 48 43 52 46 39 69 49 42 45 53 ** 52 60 - 55 68 64 68 71 70 70 73 69 63 64 74 81 77 73 85 75 39 7 S 33 43 28 0 - 43 68 38 15 41 37 ** ** 37 36 89 43 ** 5 ** ** 42 18 92 45 0 88 43 ** 42 42 45 46 Ca 7 56 AVERAGE FOR NON-NORMAL RUNS: 11.2 83 89 88 71 73 47 52 68 70 36 22 76 I 42 49 C. Saoo1 mmenta1 Tests* 21 30 22 45 23 60 11.2 85 97 ** 54 59 11.0 80 96 69 69 10.9 Ct ** a. a. a. 32 34 a. a. • CC a. ** ** ** CC 44 ** ** ** ** *C 44 ** ** a. ** a. n ** CC Analysis not performed. ------- Orqanic nitroaen was reduced by 50% durinq line preciritation treatment. The average alkalinity of the Reactor Vessel effluent was 3,300 me/liter, l3 ’ lower than the initial supernatant concentration. Removal of hardness, as expected, was best at pH 9.7. At pH 11.2 — 11.4, the hardness was reduced by 40 — with hardness removal decreasinn rapidly to zero at H 11.8. Good renoval of magnesium occurred throughout the 9.7 - 11.8 pH range, as indicated by Table X. Waste sludge volumes are indicated by Table XI. A more dense sludge was pro- duced as the pH increased, even though the amount of material removed was greater at higher pH values. Concentrating the sludge for an additional 1 to 2 hours further reduced the waste sludge volume. The concentrated waste sludge was found to dewater very well. A 2—inch layer of concentrated waste sludge (6.3% solids) lost 50% of its moisture content in a 3-hour period when placed on a 3—inch deep bed of Monterey 20—mesh sand. After 5 days, the sludge had drained and dried to a 32% solids content. Figure 12 shows the disposal area used for the pilot plant sludge during the testing at Irvington. No drainage or ponding problems were encountered, even though a considerable amount of rain fell during the six—week field test period. The effect of different concentrations of supernatant constituents upon lime precipitation effectiveness was investigated. An attempt was made to produce a stronger-than-normal supernatant by fillinq the Reactor Vessel witn Irvington 34 ------- TABLE XI u - I SLUDGE PRODUCTION Test No. Reactor Vessel pH After Lime Addition Initial Settlinq Time (Minutes) Settled S ludqe Volume (Gallons) Percent Solids Settled Sludne in Sludcje Concentration Period (Ninutes) Concentrated Sludne Volume (Gallons) Percent Solids in Concentrated Sludqe Decrp se in Net Volume of Sludne Produced 20 10.80 60 375 1.54 120 193 9.95 48.6 6* 10.85 60 375 1.57 120 204 9.98 45.6 1* 12.25 60 360 4.63 60 338 8.59 6.0 12* 9.65 60 330 2.57 120 264 2.54 20.0 14* 10.65 60 330 2.11 120 220 11.41 33.4 16 10.80 60 315 2.46 120 180 10,94 41.8 3 11.35 60 315 5.42 90 254 7.15 19.4 7 11.45 60 300 5.28 120 214 8.82 28.6 18 11.15 60 285 3.06 120 200 10.28 29.9 19 11.15 60 285 3.86 120 205 9.69 28.1 4 11.40 60 285 6.73 150 254 11.91 10.9 9* 11.40 60 285 6.91 90 272 4.5 2 11,70 60 285 5.51 90 232 9.52 18.5 5 11.40 60 270 4.88 150 234 5.98 13.3 15* 11.20 60 255 8.32 120 229 9.98 10.2 8 11.35 60 255 6.06 60 206 9.23 19.2 17 11.35 60 240 7.79 120 181 9.52 24.6 13* 11,75 60 218 5,54 120 191 6,03 12,4 11* 11.60 90 255 3.90 210 241 5.73 5.5 10* 11.50 -___ 120 210 7,93 1260 153 16,1 26,9 * Non-Normal Runs • See Appendix 1 Item A-3 ------- FIGURE 12 WaSte Sludge Disposal Area supernatant, allowing it to settle, and tnen replacing the non-settable portion with an additional amount of Irvington supernatant. A weaker-than-normal supernatant was obtained by diluting the Irvington supernatant with plant secondaryeffluent. Table XII presents a comparison of tne results achieved. It is interesting to note that the artificially “strong supernatant was characterized chiefly by the increased solids concentration; phosphorus and bC values were relatively unaffected. There was no readily apparent reason for this This phenomenon should be further investigated in future work. * cl. :4 ) T. • —‘4 36 ------- TABLE XII EFFECT OF SUPER ATANT STRENGTH ON LIME PRECIPITATION PERFORMANCE* AVERAGE DILUTED CONCE TRATED SUPERN/\T/\NT SUPER ATAI’4T (TEST NO.13) SUPERNATA T (TEST NO. 9) Supernatant Temperature 83 73 82 before Lime Addition (°F) Reactor Vessel pH after 11.3 11.8 11.4 Lime Addition Influent Total Phosphorus 142 90 149 Concentration (mg/liter) Removal in Reactor Vessel 85% 86% 87% Influent Total Ortho-PO Concentration (mg P liter) 106 ** 111 Removal in Reactor Vessel 90% ** 91% Influent Soluble Ortho-P0 4 66 46 66 Concentration (mg P/liter) Removal in Reactor Vessel 94% 94% 97% Influent Suspended Solids Concentration (mg/liter) 2,251 1,010 3,520 Removal in Reactor Vessel 64% 69% 79% Influent TOC Concentration 1,239 1,145 1,260 (mg/liter) Removal in Reactor Vessel 52% 67% 56% * After 60 minutes carbon dioxide stripping and 6,000 mg/liter slaked lime dosage. Refer to Appendix for explanation of these test conditions, Item A-3. ** Analysis not performed. 37 ------- The “weaker” test supernatant had lesser concentrations of all constituents. From the ‘imited data on Table XII, it appears that the effectiveness of lime precipitation treatment was essentially the same in all cases. This suggests that the relative degree of removal of phosphorus, S.S., and TOC is a function of the Reactor Vessel pH level and is relatively independent of the concentra- tion of the various supernatant constituents. It may, therefore, e desirable to draw a “stronqer” supernatant to achieve more relative benefit per Dound of lime used. This could possibly reduce the digester capacity required, (parti- cularly secondary digester capacity) in a two-stage digestion system. This premise will be more closely investigated in future work. The effect of using lime precipitation settling times other than one-hour was also investigated. The data, summarized in Table XIII, indicate one hour is the optimum settling period. In summary, sufficient information was collected to establish design criteria for lime precipitation treatment of Irvington supernatant. Assuming prior carbon dioxide stripping to raise the supernatant p11 to at least 8.2, a slaked lime dosage of 6 grams per liter is required for the Irvington WTP digester supernatant. This will normally produce a pH of 11.2 to 11.4 and will assure that a pH of at least 10.8 is achieved. A total of 15 minutes should be allowed for flash—mixing and flocculation. Quiescent settling for 45 to 60 minutes is indicated, For a continuous flow system, a 60-90 minute settlino period should probably be used. A volume of sludge equal to 10 to 15% of the treated supernatant volume will be produced when a one—nour settling period is used; additional settlinq time will produce a lesser volume of sludge. The 38 ------- TABLE XIII EFFECT OF REACTOR VESSEL SETTLING PERIOD * Refer to Appendix for explanation of these test conditions, Itecn A—3. ** Analysis not performed. ‘.0 30 Minute* 45 Minute 1 Hour 1 .5 Hour 2 Hour Settling Settling Settling Settling Settling Test No. 21 Test No. 22 Normal Test No. 11 Test No. 10 Operation Reactor Vessel pH After Lime Addition 11.2 11.0 11.3 11.6 11.5 Influent Total Phosphorous Concentration (mg/i iter) 148 145 142 143 140 Removal in Reactor Vessel 85% 80% 85% 87% 8 % Influent Soluble Ortho-P04 Concentration (mg P/liter) ** 106 ** 105 Removal in Reactor Vessel ** 90% ** 90% Influent Total Ortho-P0 4 Concentration (mg P/liter) 82 84 66 66 68 Removal in Reactor Vessel 97% 96% 94% 94% 97% Influent Suspended Solids Concentration (mg/liter) 2,200 3,775 2,251 2,110 1,640 Removal in Reactor Vessel 54% 69% 64% 81% 70% Influent TOC Concentration (mg/liter ) 1,080 1,180 1,239 1,040 1,060 Removal in Reactor Vessel 32% 34% 52% 52% 50% ------- waste sludge dewaters well and can be readil.y disposed of on conventional sludge drying beds. Where large volumes of suiernatant are to be treated, re— calcination and reuse of the waste lime sludge could e advantageous. PACKED-COLUMN AMMONIA—STRIPPING Good-to-excellent removal of ammonia was achieved over a wide ranoe of operating conditions. The pilot plant performance was particularly impressivt in view of the fact that it was receiving approximately twice as much ammonia as the pilot plant was designed for. Previous researchers (2) have reported that digester supernatants contain an average of about 430 mg/liter of ammonia-nitrogen. T ie Phase One work involved supernatants containing 250-boO mg/liter of 4H3-N. Tne pilot plant ammonia-stripping system was nominally designed to handle an input supernatant NH 3 -N concentration of 400 mg/liter, while the actual applied NH 3 —N at Irvinqton averaged 853 mg/liter. The versatility of tile pilot plant was therefore well demonstrated. P monia-stripping results are summarized in Table XIV. The data are divided into two groupings, representative test runs and non-representative test runs. Representative test runs were those made under conditions which could reason- ably be expected in a properly-designed supernatant beneficiation system. A description of conditions existing during non-representative runs is included in the Appendix. As Table XIV indicates, the average ffl3-f’1 removal under rep- resentative operating conditions was 82%. A maximum removal of 98% was achieved at pH of 11.6 and an air—to—water (A/w) ratio of 870 cubic feet per gallon. Overall, 80-95% removal could be achieved when pH was in the 11.2 to 40 ------- TABLE XIV N lONIA NITROGEN REMOVAL SW8IARY Test No. Influent Supernatant pH Influent SupErnatant Concentration ( ei /1iter) Strlppinq Column No. 1 Column Effluent Influent Concentration p 11 (me/liter) Percent Removal Pilot Plant Effluent pH Pilot Plant Effluent Concentretion (na/liter) Percent Removal Column Linuid Flow Rate (non) A / l Ratio A. Tests Made Under Representative Conditions 0 2 16 3 7 18 8 15 4 6 22 23 11 7.3 7.1 7.3 7.2 7.3 7.3 7.3 7.4 7.2 7.2 7.2 7.3 830 925 822 794 814 824 854 839 829 879 462 871 11.1 10.8 11.4 11.4 11,2 11.4 11.2 11,4 10.8 11.0 10,0 11.6 466 452 515 343 426 308 247 278 285 00 44 39 44 51 37 57 51 63 71 67 66 91 92 96 11.8 10.5 11.3 11.2 10.8 11.1 10.5 11.3 10.2 9.5 9.6 10.9 282 255 315 158 212 210 67 99 125 71 70 18 66 72 62 80 76 75 92 38 8o 92 92 98 13.5 11.6 10.1 10.1 13.0 14.4 10.1 10.1 10.1 6.1 5.1 5.1 145 163 225 225 280 360 455 470 530 690 825 870 437 AVERAGES FOR REPRESENATIVE RUNS: 7.3 850 11.2 292 66 10.7 157 82 10 B. lests liade Under Non- Representative Conditions 0 1 7.4 873 12.3 14 7.2 895 10.7 5 7.3 834 11.4 20 7.2 858 10.8 19 7.3 866 11.2 9 7.3 799 11.4 10 7.3 827 11.5 13 7.2 553 11.8 17 7.3 874 11.4 12 7.3 858 9.7 21 7.1 ** ** 513 437 451 524 401 275 280 165 ——— 378 0* 41 51 46 33 54 66 66 70 . — 56 0 * 12.3 10.2 11.2 10.4 10.7 11.1 11.2 11.5 11.3 8.9 t* 308 242 265 195 179 97 119 49 195 235 ** 65 73 68 77 79 88 86 91 78 73 0* 14.8 12.3 11.5 13.0 13.0 13.0 13.4 12.3 10.1 10.1 0* 145 183 185 275 275 345 345 400 455 470 0* * For explanation of Non—Representative Conditions, see Appendix, Item A—4. Analysis not perforn d. ------- 11.4 range, at an A/I ’! ratio of 350 — 450 cubic feet per qallon. A p of 11.4 — 11.6 was normally required to assure at least 8 % 4H 3 -N removal. The data surnarized in Table XIV indicate qenerally that NH 3 -N rehioval efficiency increases as the pH is raised, and/or as the A/W ratio is increased. It may be seen from Table XIV that most of the NH 3 - removal occurred in tne first stripping column. For the tests run under representative conditions, the removal in the first strippinci column averaged 66% and overall removal through both columns averaged 82%. That is, four—fifths of the 11H 3 —N removal took place in the first strippinri column. Since the pilot plant aniaonia- stripping is done in a counter—flow system, the first column NH 3 -d removal was achieved using air which was already partially saturated with NH 3 -N after passing through the second column. Therefore, Run #17 was made using only one column. The pH was 11.3, and the A/W ratio was 455 cubic feet per gallon. Test #17 is comparable to Test #4, a conventional two—column test under similar conditions. It may be seen that the single column removal (78%) significantly exceeds the first column removal (67%) achieved in two—column series operation. These data, taken together, reveal that the pilot plant columns provided con- siderably more depth of stripping column media than was beinq effectively utilized. Therefore, stripping column design for full-scale beneficiation facilities for Irvington—type supernatants can reasonably utilize a lesser depth (and therefore a less volume) of stripping column media. A conservative 25% reduction in the depth and amount of column media would appear to be justified. This would mean provision of 13 cubic feet of media per gpm of through-put and a 12-foot depth of media. 42 ------- The supernatant used in Test #13 was diluted to give a lower, and presumably normal, i’1H3—N concentration. Ammonia removal was not siqnificantly better than that achieved with full strenqth supernatant. Figure 13 and Table XV indicate the increased NH 3 -H removal efficiency which is associated with increasing air-to-water ratios. However, as A/W ratios are in creased above 450 - 500 cubic feet per gallon, the relative benefit tends to decrease rapidly. Temperature data relative to anrnonia removal are presented in Taule XVI. The ambient air temperature was not a significant factor over the temperature range encountered at Irvington, 50° — 86°F. The air was warmed as it passed through the blower, with cool air beinq warmed proportionally more than warmer air. The net effect was to produce warm influent air of relatively uniform temperature. Under the conditions at Irvington, injection of steam to raise the temperature of the stripping column air does not appear necessary. Com- parison of Run #16 (no steam) with Run #14 (using steam) reveals only slight benefit from steam injection. Runs #3 and #19 also support the conclusion that provision of steam generating facilities at Irvington is not economically justified. 43 ------- FIGURE 13 100- — AMIIONIANITROCEN REMOVAL VS A/W RATIO A 90- > 0 80- 4 ) 60- — 50- — 40- 1 1 I I 0 100 200 300 400 500 600 700 800 900 A A A A A/W Ratio ------- TABLE XV AMMONIA—STRIPPING REQUIREMENTS Test No. Strippino Column Influent pH A/W Ratio Percent Overall NH 3 —N Removal Thousands of Cubic Feet of Air Required per Pound of NH 3 -N Removed A. Tests Made Under Representative Conditions 3 11.4 225 62 53.1 2 11.7 145 66 31.7 16 10.8 163 72 29.2 8 11.4 360 75 70.3 18 11.2 280 76 50.7 7 11.4 225 80 42.3 6 10.8 530 85 90.2 4 11.4 470 88 76.1 15 11.2 455 92 69.3 22 11.0 690 92 102.3 23 10.9 825 92 124.8 11 11.6 870 98 122.2 AVERAGES FOR REPRESENTATIVE RUNS: B. Tests Made Under Non-Representative Conditions* 1 12.3 145 65 30.7 5 11.4 185 68 38.9 14 10.7 183 73 33.6 12 9.7 470 73 90.4 20 10.8 275 77 49.7 17 11.4 455 78 80.3 19 11.2 275 79 48.0 10 11.5 345 86 58.4 9 11.4 345 88 58.9 1.3 11.8 400 91 95.1 21 ** ** ** ** * For explanation of Non-Representative Conditions, See Appendix Iten P-4. ** Analysis not performed. .9 45 ------- TAL3LE XVI AMfiOrlI A SIR] O ] NG TE’IPERATURE SUMMARY Test No. Stripoino Column Influent p11 9/14 Ratio AMbient Al r Temperature F Compressed Al r Temperature °F Stri pinq Column Air Temperature F Percent Overall 883.-N Removal Percent Removal Through Column No. 1 Percent Reimoval Throu Rh Column No. 2 A. Tests Made Under Representative Conditions 4 6 11 16 3 7 15 8 18 22 23 2 11.4 10.8 11.6 10.8 11.4 11.4 11.2 11.4 11.2 11.0 10.9 11.7 470 530 870 163 225 225 455 360 280 690 825 146 56 57 58 58 58 61 62 62 62 68 68 86 79 83 85 88 82 84 80 86 84 93 86 87 59 63 63 72 64 66 64 66 70 68 67 68 88 85 98 72 62 80 92 75 76 92 92 66 67 66 96 51 37 57 71 63 51 91 92 44 21 19 2 21 15 23 21 12 25 1 0 22 AVERAGFS FOR REPRFS [ NIAT!VL 11.2 RUNS: 437 63 85 66 1.2 66 15 B. Tests Made Using Steamed Air 19 20 14 11.2 10.8 10.7 275 275 183 59 51 67 84 84 102 74 76 82 79 77 73 54 39 51 25 38 7? C. Tests Made Under Other Non-Reoreseetative Conditions* 17 11.4 455 50 74 70 78 —- 7, 20 11.5 345 56 80 65 86 66 20 12 9.7 470 60 80 63 73 66 17 13 11.8 400 61 85 63 91 70 21 5 9 1 21 11.4 11.4 12.3 *.* 185 345 145 -- 80 80 90 -- 88 88 91 ** 66 65 71 -- 68 88 65 ** 46 66 41 ** 22 22 24 *• • For explanation of Non—Representative Conditions, see Appendix, Itmn 4-4. Analysis not performed. 46 ------- SECTION VIII DISCUSSION The data and general process performance information obtained by operating the pilot plant at the Irvington WTP was straightforward and consistent. The re- sulting design criteria provide a reliable basis for design of full-scale supernatant beneficiation facilities at the Irvington NIP or at any wastewater treatment plant producing a similar type and quality of supernatant. IRVIUGTON WTP SYSTEM : The Irvington plant is designed for a 10.5 NIGD flow; current flow is about 5 I GD. Since present supernatant production amounts to 15,000 — 18,000 gallons per day, a “design” supernatant volume of 36,000 gallons per day is indicated. Sludge is pumped to the digesters every half-hour, with the duration of pumping controlled on a sludge—density basis by automatic sensing equipment. This re- suits in a fairly steady and continuous supernatant discharge by displacement from the two fixed—cover digesters. The Irvington plant has been designed to be self-operating. It is manned by operating personnel from 8:00 AM until 4:30 PM on a six days per week basis. It is therefore desirable that superna- tant beneficiation also be done on an “automatic” and self-operating basis. A design flow rate of 30 gpm is indicated. Under normal design conditions, this would permit the average daily 24-hour volume of supernatant to be pro- cessed in a 20-hour period. 47 ------- The proposed system includes a flow—equalization tank. Supernatant would be drawn from the flow-equalization tank and passed through the beneficiation pro- cess at the 30 gpm design rate. Under the design conditions, the volume of supernatant discharged to the flow—equalization tank will average 25 gpnl. Therefore, once the beneficiation process is begun, the net outflow will exceed the net inflow, and the tank liquid depth will gradually be reduced. . Jhen a pre—set minimum level is reached, the entire beneficiation process will auto- matically shut down. The process will remain off until the flow-equalization tank has refilled to a pre-determined liquid level, at which point the bene— ficiation process will automatically re-start. Sufficient flow-equalization tank volume should be provided to ensure that the beneficiation process, once started, will operate for at least several hours before the minimum tank level is reached. Under these conditions, tne lime precipitation and ammonia-stripping processes will operate under stable flow conditions. This should enhance the effectiveness of the lime treatment, especially. The flow equalization tank should have a diameter of 12.5 feet, an overall height of 13 feet, and a cone—shaped bottom. This will provide enough volu.ie to asst re that the beneficiation process, once begun, will operate for at least a 4—hour period even when supernatant release is only one-quarter of the design rate (i.e., half of the present rate). This size tank will also pro- vide enough freeboard to accommodate temporary supernatant discharge rates in excess of the design discharge rate. 48 ------- Carbon dioxide would be stripped out in the flow—equalization tank. At the recommended volume, the average liquid detention period will be iell in excess of one hour (often several hours). Pilot plant results demonstrated that an A/W ratio of 16.5 cubic feet per gallon would produce essentially complete re- moval of C32 and a resultant 8,2 pH. On the basis of the design supernatant discharge rate (25 gpm), air should be supplied at a 430 cfm rate. The air blower should be capable of operating against the maximum expected liquid depth of about 8.5 feet of water. A low—head 25 gpm capacity pump would be used to transfer the supernatant from the flow-equalization tank to the flocculator/clarifier for phosphorus removal. A chemical feeder capable of adding 90 pounds of hydrated lime per hour to the transfer stream would be required. Pilot plant operation determined the lime requirement to be 50 pounds per thousand gallons (i.e., 6 gms per liter) of pH 8.2 supernatant. The overall lime requirement would, therefore, be about 1800 pounds per day under design conditions (total plant flow of 10.5 MGD). Since the precipitate produced by lime treatment is predominantly calcium carbonate, and considering that the process will operate at a constant flow rate, a conventional upflow flocculator/clarifier unit should produce good results. A very small commercial flocculator/clarifier tank should afford ex- cellent settling conditions. A 10-12 foot diameter unit would provide an overflow rate of less than 600 gallons per square foot per day and a detention time of more than 2 hours. 49 ------- Pilot plant results demonstrated that waste sludge production would amount to 10-15% of the process through—put and would dewater very readily. For tie ful1-sca e process at Irvington, 4000-4500 gallons per day of waste sludge can be anticipated. This is a relatively snail volume compared to the Irvinqton plant sludge drying and disposal facilities. It would therefore prooably not be necessary to provide any additional sludge—disposal facilities. Also, only a minimum amount of re—piping would be required to permit use of the ex- isting sludge pumping facilities to deliver the waste lime sludge to the sludge disposal area. The effluent from the flocculator/clarifier should have a p(-( of 11.2 - 11.4 and would be pumped directly to and through the ammonia-stripping column. Pro- viding 13 cubic feet of stripping media at a 12 foot media depth would require 32.5 square feet of cross—section area. A 6.5 foot diameter column 16 feet high would provide the required volume and depth, including a 4 foot allowance for column freeboard and necessary under-clearance. The design air require- ment at an A/v! ratio of 500 cubic feet per gallon would be 15,000 cfm at 2 psi pressure. The effluent from the ammonia-stripping column would consitute the overall beneficiation process effluent. At the Irvinqton plant, the treated superna- tant could drain by gravity to the plant headworks. 50 ------- Figure 14 indicates a proposed Irvirtgton WTP supernatant beneficiation system capable of meeting full-flow (10.5 MGI )) desiqn requirements. The system would require the following: a) One flow-equalization tank, equipped with air diffusion equipment for CO 2 stripping. A tank 9.5 feet deep and 12.5 feet in diameter, with a 3.5 foot deep conical bottom, is suggested. b) One air blower capable of supplying 400 cfm of 5 psi air for removal of carbon dioxide by air stripping. c) Two low-head (10 psi) pumps of 30 gpm capacity. d) One combination flocculator/clarifier capable of providing an over- flow rate of less than 600 gallon/foot 2 /day and at least 1.5 hours detention time at a 30 gpm flow rate. e) One chemical feeder capable of feeding 90 pounds of slaked lime Ca(OH) 2 per hour. f) One 16 foot high by 6.5 foot diameter ammonia—stripping column. g) 387 cubic feet of 2-inch “Intalox” saddles (stripping media). h) One blower capable of providing 15,030 cfm of 2 psi air for ammoni a-stripping. 51 ------- FIGURE 4 RECOMMENDED FACILI TIES FOR BE NEFICIATION OF IRVINGTON WTP DIGESTER SUPERNATANT —I 5000 CFM AIR BLOWER F OR AMMONIA-STRIPPING GRAVITY DRAIN TO PLANT HEADWORKS U, N) FLOW-EQUALIZATION AND C0 2 - STRIPPING TANK max. liquid voIurne 8I0O gallons, 12.5 ftdiam. 30 GPM WASTE SLUDGE DISCHARGED TO DRYING BED VIA EXISTING PUMP AND PIPING ------- GENERALiZED SUPERNATANT BENEFICIATION SYSTEM FOR 50 MGD PLANT : The data obtained through operation of the Supernatant Beneficiation Pilot Plant at Irvington should be generally applicable to similar plants, regardless of size. A possible supernatant beneficiation system for a 50 !1GD trickling filter plant with good sludge handling and sluthie concentration facilities is presented in Figure 15. The 50 MGD plant would produce about 175,000 gallons of supernatant per day, It can be reasonably assumed that a plant of 50 1GD size could be operated to release the supernatant at a maximum rate of not more than 15% higher than the average overall discharge rate. The indicated 50 iGD supernatant flow rate for design purposes is therefore 140 gallons per minute. This is a sufficient volume of flow to justify a full—time continuous flow system. Use of a small foam spray, de-foamant chemical or proper tank baffling could eliminate or control foaming difficulties during air—stripping of carbon dioxide. This would permit a reduced detention time in the carbon dioxide strip- ping vessel. Therefore, a 30-minute stripping period at an air flow of 16 cfm per square foot of liquid surface area (i.e., 800 cfm for each 50 square feet of surface area) could be used. The total stripping air requirement, at an A [ J ratio of 15 cubic feet of air per gallon of through-put, would be 2100 cfm. A tank 13 feet in diameter with a 5 foot operating water depth would suffice. Under the circumstances of the design situation (steady, continuous supernatant discharge), gravity flow to and through the flocculator/clarifler can be 53 ------- FIGURE 5 TYPICAL SUPERNATANT BENEFICIATION FACILITIES FOR 50 MGD PLANT* I 2100 CFM I AIR BLOWER — FOR C0 2 -STRIPPING ] 70000 OE M AIR BLOW IR TO PLANT HEAL WORKS INFLUENT SUPERNATANT u - i MAKE-UP LIME CARBON DIOXIDE STRIPPING 4200 GALLONS 13 ft. r i diarn. $ LIME FEEDER 420 lbs/hr *PRODUCING IRVINGTON-TYPE SUPERNATANT ------- assumed. A chemical feeder capable of feeding at least 420 pounds of hydrated lime per hour would be needed. Ten thousand pounds of lime would be required per day. At this rate of use, re—calcining and lime reuse is indicated to avoid or minimize sludge disposal problems. Previous investigators (4) have reported that re-calcining produces reclaimed lime at a cost about equal to the price of new lime; however, re—calcining greatly reduces the excess solids disposal re- quirement and is thereby justified. A flocculator/clarifier unit 25 feet in diameter and 8 feet deep iould provide an overflow rate of less than 600 gallons per square foot per day and a detention period of just under 3 hours. After flowing from the diciester and tnrough the flocculator/clarifier by gravity, the supernatant would need to be pumped to and through the ammonia—stripping column. A 140 gprn medium-head (40—50 feet of water) pump would be required. A total of 1820 cubic feet of 2—inch Intalox saddles would be needed for ammonia stripping. A media depth of 12 feet would require 151 square feet of stripping media cross—sectional area. This could be a column 14 feet in diameter or a 12.5 foot by 12.5 foot square column. An overall column height of 16 feet should be ample. The ammonia—stripping air requirement at an A/W ratio of 500 cubic feet per gallon would be 70,000 cfm of low pressure (2 psi) air. 55 ------- Equipment and facilities required for supernatant beneficiation at a 50 MGD trickling filter plant would include the following: a) A 13 foot diameter by 5 foot deep tank for stripping carbon dioxide from the raw supernatant. The tank should have provisions for con- trolling foam. b) One air blower capable of supplying 2100 cfm of 5 psi air for strip- ping carbon dioxide. c) One medium-head 140 cipm pump. d) A flocculator/clarifier capable of providing an overflow rate of less than 600 gallons per square foot per day and at least 1.5 hours de- tention time at a 140 gprn flow rate. This would require a unit about 25 feet in diameter and 8 feet deep. e) Chemical feeder capacity sufficient to feed hydrated lime at a rate of 420 pounds per hour. f) A lime re—calcining system capable of handling 22,000 gallons of lime sludge (6% solids) per day. g) One 14 foot diameter by 16 foot high ammonia-stripping column. h) 1820 cubic feet of 2 inch “Intalox” saddles (stripping media). i) One blower capable of providing 70,000 cfm of 2 psi air for arnonia— stripping. ------- SECTION IX ECOWO1IC CuWSIU RATIOWS Removal of nutrient materials by means of the superiiatant beneficiation .process offers a number of economies. The dollar-cost advantages are mostly associated with the high concentrations at which nitrogen and pnosphorus occur in digester supernatants. Pilot plant operation required slightly less than 50 pounds of hydrated lime per pound of phosphorus removed from Irvington WTP supernatant. When phosphorus is present at low concentrations (8-10 mg/l), a lime requirement of 58 pounds per pound of phosphorus removed has been reported (3). It therefore appears that removal of phosphorus from concentrated waste streams could be accomplished at a slightly lower operating (i.e., chemical) cost. Lime precipitation capital costs are reduced in proportion to the increased concentration of phosphorus. Tank volume required per pound of lime removed is 93% less than is required for “conventional” lime precipitation (where tne phosphorus concentration is low, 15 mg/i or less). This could represent a major cost savings for situations where only partial removal of wastewater phosphorus is required. Similar economies exist relative to nitrogen removal. Where 4H 3 -N is present at low concentrations (25—35 mg/i), it has been reported (3) that 480 cubic feet of air per gallon was required to achieve 60-95% ammonia removal 57 ------- efficiency. This amounts to a strippinq—air requirement of 1,7 3,8 million cubic feet of air per pound of arnonia nitrogen removed. Under circumstances where removal of only the N11 3 —N in the digester supernatant is acceptable, only 83,000 cubic feet of air are required per pound of W1 3 -H removed. Tne capital cost for tankage is likewise greatly reduced. The incidental improvement in overall supernatant quality also can be con- sidered an operating economy. The 50-65% removal of suspended solids, TOC, COO, and organic nitrogen which occurs in the course of the phosphorus and nitrogen removal means a reduction in the net load applied to the secondary treatment facilities. Thus the removal of nutrient materials from the super- natant has the side benefit of incrementally increasing the overall treatment plant efficiency. 58 ------- SECTIO X ACKWOWLE DGEMEI4TS The work described in this report was performed by the Environmental Engineering Department of the FMC Corporation Central Engineering Laboratories. The need for an investigation of this type was originally perceived by personnel of the FWQA Advanced Waste Treatment Laboratory. The project was sponsored by the Federal Water Quality Administration of the U. S. Department of the Interior under the terms of Contract No. 14-12-414. Field testing and operation of the pilot plant was done by James E. Ournanowski, who also contributed significantly to the preparation of this report. Initial process conceptualization and preliminary laboratory investigations were done by R. A. Fisher, 1. F. Hobbs, and R. W. Prettyman. Other t,EL personnel who made significant contributions were F. F. Sako, W. G. Palmer, J. P. Pelmulder, W. F. Conley, W. A. Hendricks, C. Najera, N. Meister, T. Liddicoat, and A. Charlebois. The complete cooperation of the Union Sanitary District, Fremont, California, is gratefully acknowledged. Particular thanks are expressed to Art Duarte, Lee Doty, John Silva, and Joe Vierra. The continuing attention, interest, and guidance of Mr. Edwin F. Darth, FWQA Contract Offi cer, is gratefully acknowledged. / George E. Bennett, Engineer-in-Charge 59 ------- REFERENCES (1) Environmental Engineering Progress Report R—2826, “Phase I: Development of a Process to Remove Carbonaceous, Nitrogenous and Phosphorus laterials From Anaerobic Digester Supernatant and Related Process Streams”, Central Engineering Laboratories, FMC Corporation, Santa Clara, California (lay, 1969). (2) Masselli, Joseph W., et.al., “The Effect of Industrial Wastes on Sewage Treatment”, New England Water Pollution Control Commission, Boston, Massachusetts (1965). (3) Smith, C. E. , and Chapman, R. L. , “Recovery of Coagulant, i itrogen Removal, and Carbon Regeneration in Waste Water Reclamation”, FWPCA Report, WPD-85 (June, 1967). (4) Cuip, Russell L., “The Status of Phosphorus Removal”, Public Works Magazine (October, 1969). 61 ------- P PPEflDI X 63 ------- ITEM A-1 SUMMARY OF LIME PRECIPITATION FIELD TEST CONDITONS TEST NO. TEST CONDITIONS 1 The normal operating sequence* was followed, except that slaked lime dosage was 6,840 mgI liter and sludge concentration period was only one hour. 2 Normal operating sequence, except that the sludge concentration period was 90 minutes. 3 Normal operating sequence, except that the sludge concentration period was 90 minutes. 4 Normal operating sequence, except that the sludge concentration period was 2—1/2 hours. 5 Normal operating sequence, except that the sludge concentration period was 2—1/2 hours. 6 Normal operating seiuence, except that the carbon dioxide stripping time was only 30 minutes. 7 Normal operating sequence. 8 Normal operating sequence, except that the sludge concentration period was only one hour. 9 Normal operating sequence, except that the sludge concentration period was 90 minutes. 10 Normal operating sequence, except that the settling period was 2 hours and the sludge concentration period was 21 hours. 11 Normal operating sequence, except that the settling period was 90 minutes and the sludge concentration period was 3—1/2 hours. * 4ormal operatinci sequence is carbon dioxide stripping for 60 minutes at 550 cfm 1 lime dosage of 6,000 mg/liter, 15 minutes flocculation, 60 minutes settling, and a 2 hour sludge concentration period. 65 ------- sur•1:IARY OF LLIE PRECIPITATION FIELD TEST CO DITIO, S TEST NO . 1L LU DITIOfJS 12 Normal operating sequence, except that the carbon dioxide stripping time was 15 minutes and the lime dosage was 4,500 mg/liter. 13 Normal operating sequence, except that the lime dosage was 4,500 mg/liter. 14 Normal operating sequence. 15 Normal operating sequence, except that the carbon dioxide stripping time was 45 minutes. 16 Normal operating sequence, except that steam was added to the carbon dioxide stripping air. 17 Normal operating sequence. 18 Normal operating sequence. 19 Normal operating sequence. 20 Normal operating sequence, except that the lime dosage was 5,840 mg/liter. 21 Normal operating sequence, except that the settling time was 30 minutes. 22 Normal operating sequence, except that the settling time was 45 minutes. 23 Normal operating sequence, except that the carbon dioxide stripping time was only 15 minutes. 66 ------- ITEM A-2 EXPLANAT I ON OF NON—REPRESET1TAT I VE AMMONIA STRIPPING CONDITIONS TEST NO. TEST CONDITIONS 1 Stripping column influent pH was abnormally high at pH 12.3. 5 Stripping column influent was partially batch stripped in the reactor vessel prior to passing it through the columns. 9 Approximately 50% more particulate solids were present in the stripping column influent. 10 Stripping column influent allowed to stand in the reactor vessel overnight before passing it through the columns. 12 Stripping column influent pH was abnormally low at pH 9.7. 13 “Half-strength’ test; NH 3 —N content was 553 mg/liter versus the average concentration of 835 mg/liter. 14 Steam utilized to add heat and moisture to the ammonia stripping air. 17 Only one ammonia stripping column utilized. 19 Steam utilized to add heat and moisture to the ammonia stripping air. 20 Steam utilized to add heat and moisture to the aPii onia stripping air. 21 Test used only to check carbon dioxide stripping rates at various air flows. No an rionia stripping done. 67 ------- SAM FL V•29 --- - - . — -—v —-i WASTE V -2 i V-i I V-I 2 — .-- _w . j — -.-i V-H VIASTE__ V- 10 SAMPLE V-2 8 DECANT TAN K // H \ // k -2 \ /‘ H-I - V35\/ ‘>. - ‘AT i P IETER V --V- i V 2 2 )‘ H AMPLE PUMP PUMP V-30 STEAM LINE - ----- r LEGEND; P--PUMP V — VALVE H —QUICK-DISCONNECT COUPLING SW- FLOAT VA L VE ITEM A—3 FUIICTIONAL PIPING UIAGRA:i OF TRAI LER-MOUNTEL) SUPERNATANT L ENEFICIATION PILOT PLANT U V -3 1 P [ f ’ C T I’) N TA N K - Al P I .- N E SW - ------ .- — - - - - -. - -— - V E N T V33 HME AV I NC -iii C - ’ t. [ LftJ B L ‘DW E P VN 2000 GALLON PLASTIC TANK ON GROUND FOR TREATED SUPER NATANT ------- 12/16/69 ITEM A—2 DIGESTER SUPERWATAIT TRAI LER EQUIPMENT LI ST CE 45570 EQ PMEUT DESCRIPTION SUPPLIER MANUFACTURER Corning Model 5 pH Meter Scientific Products, Corning Glass Works, with electrodes* Menlo Park, Calif. Scientific Instruments, Iledfield, Mass. 02052 Electrodes (spare set) Scientific Products Corning Glass Works for above meter. Corning Menlo Park, Calif. Scientific Instruments Series 500. Reference Iledfield, Mass. 02052 electrode Corning No. 476106, pH electrode Corning No. 476105 Malsbary Steam Generator Malsbary Ilanufacturing Co. Same Model 20D* 845 92nd Avenue Oakland, Calif. 94603 Fischer and Porter 10A3565A G. 1. Cooke Co. Fischer and Porter Co. 65 Rotameter Tube No. 935 Pardee Avenue Warminster, Penn. FP—2—27—G—lO/83 Berkeley, Calif. 94710 Float No. 2-GNSVGT98 100% Flow — 63.1 gpm Liq. Spec. GIL — 1.0* Master Combination Padlocks Orchard Supply Hardware Master Lock Company Lab Lock Code No. X2ll91 720 West San Carlos Milwaukee, Wisconsin Combination: R.-12—L—22—R-36 San Jose, Calif. Electrical Cabinet Lock Code No. X2l171 Combination: fl_6_L_20_R_34* Hastings Air—Meter Model JHS Associates Hastings—Raydist Inc. No. G—ll with 5—27 probe* P. 0. Box 1894 Hampton, Virginia 23361 San Leandro, Calif. 94577 ftii erican Water Meter Roberts and Brune American Meter Controls Series 650 20780l6T American Meter Controls Buffalo, Hew York A Niagra Liquid rleter* 1832 Rollens Road Bur1inga ie, Calif. 94010 * Operating Manuals in File 69 ------- 12/16/69 EQUIPMENT DESCRIPTION SUPPR MA UFACTURER 147 Rochester Industrial Thermometer ilodel 1740 3” Diameter dial Stainless Steel Sink and Counter Top Sections 25” Deep with 3—12” Backs p1 ash* California Instruments Co. 351 10th street San Francisco, Calif. 94103 Sears Roebuck and Co. Commercial Sales Department 1350 West San Carlos San Jose, Calif. Coronado Swimming Pool 15’ x 48” Kiddie Uorld 3640 Stevens Creek Blvd. San Jose, Calif. HPE, Inc. 225 Acacia Street Colton, Calif. Jabsco Model 6400—05 One 8681-14 and two 8674_3* Coker Pump and Equip Co. 1089 3rd Avenue Oakland, Calif. 94607 Jabsco Pump Co. Costa Mesa, Calif. Robbins and Meyers Iloyno Pump Type CDQ Fram lL6 Form VT Serial No. A_6332_1* C. U. Bosv,ell Co. 767 S. 16th Street Richmond, Calif. Robbins and Meyers, Inc. Springfield, Ohio Gorman-Rupp Self-Priming Centrifugal Pump Size 3 x 3, 7—3/4” impeller Serial No. 446853 Model lb. 83C2B Coker Pump and Equip. 1089 3rd Avenue Oakland, Calif. 94607 Co. Gorman—Rupp Co. Ilansfield, Ohio General Electric Tn-clad Induction Ilotor (Gorman- Rupp Pump) Model 5K184BL220 No. LD H.P. — 5 Serv. Fac. - 1.0, Volts — 230/460, Phase 3, Cycle — 60, Amp - 14.2/7.1, RPM 1745, Time Rating — Cont. 40 Deg. C Max. Amb. Frame - 184T, Type - K, Code - H, Ins. Class — B, NEMA Des. — B, Shaft End Brg. AFBFIA - 35BCO2XP Opp. End Brg. AFBMA — 25BCO2XP Coker Pump and Equip. Co. 1089 3rd Avenue Oakland, Calif. 94637 General Electric Ft. Wayne, Indiana * Operating Manual in File 70 ------- 12/16/69 ErUIPMEr T DESCRIPTIOi4 SUPPLI ER MAUUFACTURER General Electric A—C flotor (Steam Generator H.P. — 1/4, FR — 48, Model 5KC37 KG] 84 219500, RPM 1725 pH — 1, S.F. — 1.0, Temp. Rise — 55°C, Volts 115, Code — F l, Amps - 5.2, Cycle — 60, Time Rating — Cont. Serial Mo. WXD General Electric Supply 530 ilartin Avenue Santa Clara, Calif. 95050 General Electric Ft. Wayne, Indiana General Electric Tn—Clad Induction Motor Model No. 5K364BK134B1 Serial Ho. KE 415016, Frame - 364T, H.P. - 60, cycle — 60, pH - 3, F.L. RPM 3555, Ser. Fac. — 1.0, Time Rating — Cont., Volts - 460/230, F.L. Amps - 144/72, Type - K, NEMA Class Design — B, Code — G, Ins. Class B, flax. Amb. - 40°C, Drive End AFBf1A Brg. 70BC03, Opp. Drive End AFBVA Brg. 60BC03* Buffalo Forge C/U Richard Stities, Inc. 139 Mitchell Avenue So. San Francisco, Calif. 94080 General Electric Schenectady, Wew York U.S. Electrical Motor (T .zo) (Tower Pumps) H.P. 1, pH - 3, Cycle — 60, Frane - 143T, Volts — 460/230, Amps — 3.6/1.8, Ser. Fac. — 1.0, RPM 1710, Model No. F-l500—02—l6l, Iris. Class — B, Rating — Cont., 40°C flax. Amb. Shaft End Brg. AFBMA — 25BC02XS3 Opp. End Brg. AFBM/\ — 17BC O2X3* Horsford Brothers 1775 So. 1st Street San Jose, Calif. 95112 U.S. Electric Motors Ililford, Conn. and Los Angeles, Calif. * Operating Manual in File 71 ------- 12/16/69 EQUIPMENT DESCRIPTION SUPPLIER MANUFACTURER U.S Electrical Varidrive Horsford Brothers U.S. Electric Motors Motor, HP. - 1, P 1 — 3 ’ 1775 So. 1st Street tlilford, Conn. and Cycle - 60, Volts - 460/230 Oakland, Calif. 95112 Los Angeles, Calif. Amps - 4.6/2.3, Gear Ratio 2.79, Motor RPM 1725, RPM Mm. — 154, RPM flax. — 1540 Ins. Class - B, Frame - 6-56-5, Type VAV—JF—Gfl, Design — B, Code L, Cont. Rating — 40°C Max. Amb. Serial No. HF — 1030285, Nominal Power System Voltage 480/240 Dayton Three Phase A—C Motor W. Grainger, Inc. Dayton Electric Mfg. Co. (Moyno Pump) LR24684, 1260 No. 13th Street Chicago, 49, Illinois Model NO. 2 933—C, H.P. — 1, San Jose, Calif. RPM — 1740, Cycles — 60, Frame - 182, Duty - Cont. Risc — 55°C, Tyøe - PF, Ser. Fac. — 1.0, Code — Motor Ref. — 72145-C NP Volts - 220/208/440 Amps - 3.6/1.8 Buffalo Blower and Motor Richard Stites, Inca Buffalo Forge Co. Frame, Frame Size - 405U 139 Mitchell Avenue Buffalo, New York 14204 27” Wheel Counter—clockwise So. San Francisco, Calif. Top, Horizontal Discharge 94080 Trailer, Brown, used 27’1/2” X Redwood Reliance Co. 9l’-5/3” flatbed. Removed 141 Helmar Avenue stake pockets and ground smOoth, Cotati, Calif. 94928 straightened side rails. Ilew 1—1/8” water—proof plywood deck installed outside of main frame rails, rear shortened to approximately 24” behind axle center, no rear hitch, hoses terminated at axle, old rear cross member to be delivered loose. Steam cleaned and painted with enamel, 4 serviceable tires as is, skid plates on landing gear. After all installations, final trailer length is 30’ 5”. 72 ------- 1/21/70 EQUIPMENT DESCRIPTION SUPPLIER MANUFACTURER General Electric HT Quiet General Electric Supply General Electric Transformer. Model No. 530 Martin Avenue Ft. Wayne, Indiana 9121B1006, Hz — 60, Santa Clara, Calif. KVA - 10, Temp. Rise, — 115, Serial — KE N.P. — 183796 73 ------- 1 BIBLIOGRAPHIC Central Engineering Laboratories, Flit Corporation, Development of a Pilot Plant Ce Demonstrate Removal ACCESSION NO. of Nutrient and Carbonaceous Materials from Panaerobic Digester Supernatant, final Report, EaQA Contract Ho. 14—12-414, May, 1970. ABSTRACT Digester uapernatant contains high concentration of nitrogen and phouehoruo. Also, poor quality saperna— KEY WORDS: tant discharged from an anaerobic digester con have an adverse effect on tne overall efficiency of a waste— water treatment plant. Sludge Treatment Under the FWQA opensorship, the Central Engineering Laboratories of the fAt tomnoration, undertook to baud and demonstrate the operation of a onique, trailer—mounted, and completely onlf-contained pilot plant. Supermatant Nutrient Removal The pilot plant io designed to ineestigate tne improvement of digeoter ounernatant quality, aith particalar emphasis on the remonal of nitrogen and phooohorus, The pilot n lant treatnent sequence consists of cerooe Phospoorus Removal dinnide removal via air—stripping, lime precipitation of phesnhorus and caroonaceous purticalate matter, and removal of nitrogen by pecked—tower anemnia—utrinoing, Nitrogen Removal The pilot plant wan operated over a tao-month period at a trickling filter nlvnt where Ceo-stage anaerobic nia Stripping digeetion io practiced. The pilot plant ooerated in a reliable and consistent faonion wits respect to both the mocoanical performance and the proceon data ootained. A wide range of noerating ccnditions was in— eentigated in a convenient and effective manner. It was foend that 83—gUS of oaonrnatant nh000horus could bn removed at a lime dosage equal to 50 pounds of hydrated line per pound of phosphorus removed, Overage anronia—oitrogen removal was dOt, achieved at an air flow rate equal to 83,003 cubic feet of air per pound of lO3 J removed. Normal lime precipitation removed above one—naif of toe oupernutant TOO, LOP, and Organic ditrogen. The aeerage decrease in suopended solids vau 84%. This report is submitted In fulfillment of Contract In. 14—12—414 (Program An. 17310 ft b) between the Federal Water Quality A ninistration and the Central Engineering Laboratories of FTC Cornaratino. I — BIBLIOGR APhIC Central Engineering Laboratories • ff0 Cvrporation, Deuelopeenc of a Pilot Plant to bemonstrate Removal 800EOSION NO. of Nutrient and Carbonaceous Materials from 7 naerobic Digester Supernatant, final teoart, FOQA Contract No. 14-12—414, May, 1970. ABSTRACT Digester sapernatant contains nigh concentration of nitrogen and pnouehorus. Also, poor quality superna— KE WORDS: tent discharged from an anaerobic digester can have an uoeerse effect on the overall efficiency of a waste— water treatment o lant. Sludge Treatment Under the FWQA sponsorship, tne Central Cnginenrino Laboratories nf the fAt Corporation, undercook to beild and demonstrate the operation of a unique, trailer—mounted, nod corpletely self—contained pilot plant. Supernatant Nutrient Removal The pilot ploot is designed to investigate toe imor000mmot oi oipestem oupemnacenc iuulity, with particular emphasis on the removal of nitrogen and phoooboruo. The piloc slant oreuorvnt svbuence consists o carson Phosonorus Removal dionide remoaal via air—otripping, lime precipitation of phossnomus use corpcndcenus particulate matter, and remioeal of nitrogen by packed—tower anwhonia—scriooing. Nitrogen Removal The pilot plant was noerated over a two—month oeriod at a tr:cklinp filter nlonc whore two—stage anaerobic Ammonia Stripping digesCiemn is practiced. The olloc plant onerated in a reliaple and consistent fashion with respect to L0CO the mecnuoical oerformance and the process data ostuineo. 3 aide range of operating conditions was in— nestigated in a convenient and effeotiee manner. It was found that 83—9S of supernatant pn000horus could bo resoved at a lime dosage equal to bO pounds of hydrated line per sound of phosphorus removed. Peerage anrooia—nitrogen removal was d2P, uooieved at an air flow rate equal Ce 83,303 cubic feec of air oem pound of A 3 - ;: ronowod. Bonsai lime precipitation removed aboue one-oalf of tie ouoemnatunt ICC, LOP, and Organic itrogen. Tne aeerage decrease in suopanded solids was t4%. ibis report in submitted in fulfillment of Contract .0. 14—12—414 (Program u. 17313 fcf) between toe Federal Water Quality Atrimistration and tne Central bogineerimT Laboratories of fit Comnoracion. r — — — — —- — — 1 Central Engineering Laboratories, ff0 Corporation, Ceoelmpment of a Pilot Plant to bemonstrace Removal ACCESSION SD. of Nutrient and Caromnaceous Materials from Pwiaerooic digester Supemnatunc, final hesort, F.Qb Contract ho. 14—12—414, May, 1970. Digester supernatant conoains high concentration of nitrogen and 0 10sphorus. Also, poor quality superna- KEg WORDS: Cant discharged from an anaerobic digester can have an adverse effect on the onerull efficiency of a vance— water treutoent n lant, Sludge Treatment Under the faQA sponsnruhip, tne Central kngineoriwo Laborotonies of tse fit Ccrnorution, undertook to baud and demonstrate the operation of a unilue, trailer—mounted, and comnletelm snif—contuined pilot plant. Supemnatant NutrIent Removal The pilot plant is designed to investigate tne irpmoeersnc of dipenter ousereutenc puuliCy, with particular emphasis em the renoeal of nitrogen and phosphorus. Tne pilot plumC treaTment snquence coosists of carton Phospnnrus Removal dioxide removal via uir—ucrioping, lime precisitution of phcssnorus and curoohoceous narticalute netter, and removal of nitrogen by packed—tower amimvnia-strioniom. Nitrogen Removal The oiiot plant was onerated over a two—momth oemicd at a Cnickling filtor slant acorn twc—sCoge unaerooic Ammonia Strippieg digestion is practiced. The oilot plant ooerutvc in a reliebln and consistent fasnion wits resseot to totn the mecoanloal oerfonnaece and the process data ubtoine e. A wide ma ngo of onerucing conditions uas in— eestlgated in a onneenient and effectiuv manner. It was found that 83—95% of uupemnotant nhosoborus could n ro ineed at a lime dosage eouul to no poundu of hydrated lure oer omund of phosphorus remoevo . teeruge ammonia—nitrogen rercuul was dOt, ucnieeed at an air flow rate equal to 83,333 cubic feet of air oem pound of .n3 mempeud. Normal lime precipitation removed above one—nulf of tee supemndtunt TLC, LAP, and wmganic .itmogeo. lie aeerape decrease in suspended solids was 64t. This report uu submitted In fulfillmont of CunCracc ‘In. 14—12—414 (Progru—’ n. 17010 fc C) between Con Federal Outer Quality 7 ninisCrution and tee Central bnginderihm Lanorutcmivs of flL Corporation. ------- Accession Field & Group — SELECTED WATER RESOURCES ABSTRACTS INPUT TRANSACTION FORM Or anizat’on Central Engineering Laboratories, FIIC Corporation 6 T ,elopTnent of a Portable Pilot Plant to bemonstrate Removal of Carbonaceous, Nitrogenous, and Phosphorus Materials from Anaerobic Digester Supernatant and Similar Process Streams 10 I Author(X3 —i Bennett, George E. 16 Project Designation Progam No. 17010 FK.A/Contract No. 14—12—414 i.— Note N/A Citation N/A 23 Descriptors (Starred First) I *Djg t Supernatant, *Amonja Stripping, Nutrient Removal 25 Identifiers (Starred First) *Phosphorus Removal, *Nitrogen Removal, Sludge Treatment Digester suoernatant contains high concentrations of nitrocien and ohosohorus. fl Abstract Also, poor quality supernatant discharged from an anaerobic digester can have an adverse effect on the overall efficiency of a wastewater treatment plant. Under FWQA sponsorship, the Central Engineering Laboratories of the FMC Corporation under- took to build and demonstrate the operation of a unique, trailer—mounted, and completely self—contained pilot plant. The pilot plant is designed to investigate the improvement of digester suoernatant quality, with particular emphasis on the removal of nitrogen and phos- phorus. The pilot plant treatment sequence consists of carbon dioxide removal via air- stripping, lime precipitation of phosphorus and carbonaceous particulate matter, and re- moval of nitrogen by oacked—t er arwnonia—stripping. The pilot plant was operated over a two-month period at a trickling filter plant where two- stage anaerobic digestion is practiced. The pilot olant operated in a reliable and consist- ent fashion with respect to both the mechanical performance and the process data obtained. A wide range of operating conditions was investigated in a convenient and effective manner. It was found that 80—95% of supernatant phosphorus could be removed at a lime dosage equal to 50 pounds of hydrated lime per pound of phosphorus removed. Average amnionia-nitroqen re- moval was 82%, achieved at an air flow rate equal to 83,000 cubic feet of air per pound of NH 3 —N removed. Normal lime precipitation removed about one—half of the supernatant TOO, COD, and Organic Nitrogen. The average decrease in suspended solids was 64%. Abstractor In. t,tution Bennett, George E. Centra ] ngin rjng Laborato j, fljccc rporatinn WR 1C2 REV JUEN 1969) SENT TO: SATER RESOURCES SC ENT E )C e4POFMRTION CENTER WRS C U.S. DEPARISIENT OF THE INTERIOR WASP-IINOTON D C 2T040 U.S. GOVESNSEUT PRINTING OFFICE: 1970 0—000-096 ------- |