都市下水処理場活性汚泥における蓄積基質の挙動

抄録

The Activated Sludge Model No.3 (ASM No.3) proposed by the IAWQ Task Group includes the process of storage of organic substrates. But, it is not experimentally verified that the storage of organic substrates has principal significance in actual activated sludge processes. Moreover, the parameters for the storage of organic substrates in ASM No.3 are not selected on experimental bases. In this research, polyhydroxyalkanoate (PHA) is assumed as the principal storage product, and the capacity of storage of PHA in activated sludges obtained from seven full scale plants in Tokyo, including conventional activated sludge processes as well as those designed for nutrient removal, was examined. Sodium acetate was fed under either aerobic or anaerobic conditions to the activated sludges, and the behavior of internally stored PHA was measured. It was experimentally demonstrated that under the aerobic condition the storage process significantly affect the substrate uptake rate not only in activated sludges from the anaerobic-aerobic process for biological enhanced phosphate removal but also in those from conventional activated sludge rocesses. Parameters for storage (the synthesis rate constant: KSTO and the aerobic yield of synthesized product per Ss: YSTO, O2)were about 0.7 to 1.3 gCOD/gCOD-Ed and about 0.6 to 0.7 gCOD/gCOD, respectively.