硝化促進型SBRプロセスにおける処理特性と汚泥沈降性に及ぼす撹拌の影響

抄録

The effect of agitation on the treatment performance and sludge settleability in a SBR process in the operating condition that no NH₄-N were detected in effluent were investigated. The influent used in this study was domestic wastewater. Two agitation methods: stirring by using a stirrer and a pump were used for this study. In the condition (controlled system) that diameter of stirring impeller was 90mm and stirring speed was 100rpm, the treatment performance and settleability of activated sludge was very stable. However, in the condition that diameter of stirring impeller installed with two sheets (impellers) was 50mm and stirring speed was over 190rpm, efficiency of oxygen transfer was increased, but floc of activated sludge was segmented. It was observed that suspended solid (SS) in effluent was increased with the increase of stirring speed. Moreover, the increase of stirring speed resulted in apparent increase of sludge volume index (SVI) and caused the deterioration of sludge settleability. The flock diameter of the activated sludge dccreased from 82μm to 65μm due to the increased stirring speed from 100rpm to 190rpm.