DIGESTION WITH AIR AERATION; PILOT PLANT ANALYSIS

PATHOGENS, TOXIC METALS, AND TOXIC ORGANICS OCCUR AT LOW CONCENTRATIONS IN MUNICIPAL WASTEWATER, BUT MANY OF THESE MATERIALS ARE CONCENTRATED THOUSANDS OF TIMES IN THE RESULT ING PRIMARY AND SECONDARY BIOLOGICAL SLUDGES. A REVIEW OF THE ENVIRONMENTAL PROTECTION AGENCY'S (EPA) "SAFE SLUDGE" DESIGNATION FOR USE IN FOOD PRODUCTION SHOWS THAT NEARLY HALF OF ALL SLUDGES GENERATED CANNOT BE DEFINED AS "SAFE," THUS ELIMINATING THE COST-EFFECTIVE ULTIMATE DISPOSAL ALTERNATIVE OF LAND APPLICATION. A PROCESS THAT COULD ELIMINATE THE TOXIC CONSTITUENTS OF SLUDGE WOULD BE OF B BENEFIT TO MANY MUNICIPALTIES AND INDUSTRIES. PREVIOUS RESEARCH HAS DEVELOPED A PROCESS THAT PROMISES TO BE CAPABLE OF DETOXIFYING SEWAGE SLUDGE IN A COST-EFFECTIVE MANNER. THIS PROJECT OUTLINES THE NEXT PHASE THAT IS NEEDED TO BRIDGE RESEARCH INFORMATION WITH COMMERCIAL APPLICATION. AEROBIC DIGESTION WITH UNIQUE HIGHLY EFFICIENTSELF-ASPIRATING AERATORS WAS SHOWN TO BE CAPABLE OF AUTOHEATING SLUDGES TO PASTEURIZATION TEMPERATURES (50 CT) BY JEWELL IN A FULL SCALE FACILITY IN 1979. FUTHER DEVELOPMENT SHOWED THAT MODIFICATIONS TO THE PROCESS HAVE THE POTENTIAL OF REMOVING PATHOGENS, TOXIC METALS, AND POSSIBLY TOXIC ORGANICS IN A COST-EFFECTIVE SIMPLE PROCESS. AUTOHEATING SLURRY TEMPERATURES CAN EASILY ACHIEVE 60 C WITH MOST SLUDGES WITHOUT HEAT ENERGY ADDITONS (HIGHER TEMPERATURES WOULD BE POSSIBLE WITH HEAT EXCHANGERS), THUS KILLING ALL PATH OGENS. MANIPULATION OF THE PH IN THESE HOT AEROBIC SLURRIES SHOWED THAT GREATER THAN 80% OFMOST TOXIC METAL COULD RAPIDLY SOLUBILIZED (IN LESS THAN 3 HOURS). ALTHOUGH NOT TESTED, AERATION AT THESE TEMPERATURES WILL LIKELY RESULT INVOLATIONLIZATION OF SOME TOXIC ORGANICS. FINALLY, IT WAS SHOWN THAT THE PROCESS COULD ALSO BE APPLIED TO ANAEROBICAL LY DIGESTED SLUDGE. THIS LATER APPLICATION IS IMPORTANT NOT ONLY BECAUSE OF THE LARGE INSTALLED DIGESTION CAPACITY, BUT SHORT TERM AERATION (6 HOURS) OF ANAEROBICALLY DIGESTED SL SLUDGE RESULTS IN RAPID TEMPERATURE INCREASES, AND SIGN SIGNIFICANTLY INCREASED SETTLEABILITY AND DEWATERING CHARACTERISTICS THUS ACHIEVING UP TO 50% VOLUME REDUCTION. THUS A HYPOTHETICAL SYSTEM WITH HYDRAULIC RETENTION TIME OF LESS THAN 24 HOURS SHOULD BE CAPABLE OF NOT ONLY SUBSTANT IALLY REDUCING SLUDGE VOLUMES, BUT PRODUCE A SLUDGE THAT WO WOULD MEET EPA'S "SAFE" DESIGNATION FOR VIRTUALLY ALL ORGANIC SLUDGES EITHER AS AN ADD-ON PROCESS OR AS A NEW INSTALLATION. THIS STUDY WILL EXAMINE THE IMPACT OF THE UN UNIQUE SELF-ASPIRATING AERATORS ON THE SETTLEABILITY, DEWATERABILITY, AUTOHEATING, AND METAL REMOVAL CHARACTER ISTICS OF ANAEROBICALLY DIGESTED SEWAGE SLUDGE IN A 28M3 FULL SCALE UNIT LOCATED AT THE BINGHAMTON, NY, SEWAGE TRE TREATMENT FACILITY (A 190 MILLION 1/D CAPACITY PLANT). THREEOTHER SLUDGES REPRESENTING A WIDE RANGE OF CONTAMINANTS, W WILL BE TRUCKED TO THIS FACILITY AND USED IN SHORT TERM B BATCH TESTS. THE RESULTS OF THESE TRIALS WILL BE USED TO ESTIMATE DESIGN REQUIREMENTS AND TO ESTIMATE THE FEASIBILITYOF THE PROCESS.