ENHANCED BIOLOGICAL PHOSPHOROUS REMOVAL USING MICROBIAL CONSORTIA IN ACTIVATED SLUDGE PROCESS

Abstract

laboratory scale aerobic baffled reactor (AeBR) of 10 L capacity was used in this study to perform EBPR. The reactor was started with sludge recycled in a nearby ASP STP and then some dried powdered sludge from the same plant was added. It was operated at 1.4, 10, 20, 30 and 40 mg/L of influent phosphorus concentration in medium strength synthetic wastewater for 348 days. The phosphorus removal efficiency was high at 97% up to 20 mg/L and decreased to 63-69% and 27-33% respectively at 30 and 40 mg/L concentration of phosphorous in influent. COD removal efficiency exceeded 90% except at high phosphorus loading. It was observed that addition of dried powdered sludge helped in improving the performance of AeBR as phosphorus as well as COD removal efficiencies increased after its addition that is normally riot observed in activated sludge process. System was also able to recover from the effects of shock loadings. Finally, six different cultures were isolated from the sludge and biochemical tests were perlormed to know the characteristics of the microbes present in the sludge of AeBR. The reactor was then operated with high strength wastewater. The phosphorus concentration was varied at 3, 10, 20 and 30 mg/L. It was operated for 128 days. Results showed that high COD loading deteriorated the granular EBPR system and resulted in sludge bulking with filamentous bacteria. High COD loading probably inhibited the Extracellular polymeric substance E secretion, which completely destroyed the stability and integrality of granules. Glycogenaccumulating organisms and other microorganisms had a competitive advantage over Phosphorus Accumulating Organisms. Another laboratory scale aerobic cubical reactor of 35 L capacity was used in this study to perform EBPR using microbial consortia. Based on tracer studies, dead space in the reactor was found around 2.5% without aeration and 1 .7% with aeration. The flow pattern in the reactor was classified as intermediate between plug flow and perfectly mixed flows. .The reactor was started with consortia prepared from 12 pure strains. It was operated at 1.4 mg/L of influent phosphorus concentration in medium strength synthetic wastewater for 107 days. Efficiency for COD removal was 88%, and that for total phosphorus removal was 100%.