AN ACTIVATED SLUDGE MODIFICATION TO ELIMINATE BULKING, MINIMIZE REACTOR VOLUME AND ENHANCE NUTRIENT REMOVAL

A MODIFICATION OF THE ACTIVATED SLUDGE PROCESS HAS BEEN DEVELOPED TO ELIMINATE SLUDGE BULKING, MINIMIZE REACTOR VOLUMES, AND ENHANCE NUTRIENT REMOVALS. THE FLOW SHEET UTILIZES TWO SEGMENTS IN SERIES. THE FIRST EMPLOYS A 10 MINUTE MIXED LIQUOR CONTACTOR TO ADSORB 50-60% OF THE SOLUBLE CARBON SUBSTRATE. CONTACTOR MIXED LIQUOR IS FLOTATION SEPARATED AND DISCHARGED TO A SEPARATE AERATION REACTOR FOR METABOLISM OF THE ADSORBED SUBSTRATE. AFTER OXIDATION, MIXED LIQUOR IS RETURNED TO THE CONTACTOR. FLOTATION EFFLUENT IS DISCHARGED TO A SEPARATE ACTIVATED SLUDGE REACTOR SERVED BY A FINAL CLARIFIER AND SLUDGE RECIRCULATION. THE CONTACTOR AND OXIDATION REACTOR OPERATE UNDER ANOXIC CONDITIONS TO MINIMIZE POWER CONSUMPTION FOR AERATION. OXIDATION REACTOR TEMPERATURE MAY BE VARIED BY VARIATION OF THE SOLIDS CONCENTRATION OF THE FLOAT. THIS RESULTS FROM THE EXOTHERMIC CHARACTER OF BIO-OXIDATION. HIGH CONCENTRATIONS OF SEPARATED SOLIDS IN THE OXIDATION REACTOR MINIMIZES ITS VOLUME. CONTACTOR OPERATION ELIMINATES THE GENERATION OF FILAMENTOUS ORGANISMS IN THE SUBSEQUENT ACTIVATED SLUDGE REACTOR THUS ELIMINATING SLUDGE BULKING AND DETERIORATION OF EFFLUENT QUALITY. SUBSTRATE-RICH WASTE SOLIDS MAY BE OBTAINED BY WASTING UPSTREAM OF THE OXIDATION REACTOR THUS ENHANCING GAS PRODUCTION FROM ANAEROBIC DIGESTION. SEPARATE ORGANISM POPULATIONS ARE MAINTAINED IN EACH FLOW SHEET SEGMENT. THE CONTACTOR SEGMENT HAS OPERATED SUCCESSFULLY UP TO AN F/M OF 35 LB 30D/LB MLVSS/DAY AND THE ACTIVATED SLUDGE SEGMENT UP TO AN F/M OF 2.0 DAY (-1). SLUDGE AGE IS THUS MINIMIZED IN BOTH SEGMENTS AT LESS THAN 1-2 DAYS. RECENT RESEARCH VERIFIES THE RELATIONSHIPS BETWEEN SLUDGE AGE AND NUTRIENT CONTENT OF WASTE BIOLOGICAL SOLIDS. THE CAPABILITY TO OPERATE AT MINIMUM SLUDGE AGE WITHOUT BULKING THUS PROVIDES FOR MAXIMUM CONTENT OF NITROGEN AND PHOSPHOROUS IN SYSTEM WASTE SLUDGE.