UASBの処理安定性に対する処理水循環の影響に関する実験的研究

抄録

Effect of recycling of effluent on the performance of UASB reactor is investigated using glucose as organic substrate. The reactor was operated on recycling and no recycling mode. Effects of the operating parameters such as total organic carbon (TOC) loading rate, recycling ratio and upflow velocity on the performance of UASB reactor were evaluated. The result showed that recycling could increase upflow velocity and energy consumption; maintain uniform distribution of substrate, and reduce the rate of decomposition of glucose to organic acids. When the reactor was operated without recycling, organic acid accumulation was increased and pH was low at the bottom of the reactor. During no recycling mode of operation, the maximum loading rate was found to be 12.8kg-TOC/m³. d at 35°C. When TOC loading rate was 7.6kg-TOC/m³. d, the effect of recycling on TOC removal efficiency was negligibly small.
At the low temperature shock, TOC removal efficiency dropped from 95% to 52.6%, when the reactor was operated with recirculation and the system appeared to return to its normal state, after five weeks of recovery period. However, when the system was operated without recycling, TOC removal efficiency dropped by 3.6%, and needed only forty-eight hours for recovery. Therefore, at the low temperature shock, the system without recycling showed better stability.