Change of microbial community structure by respiratory quinone profile at intermittently aerated membrane bioreactor

In the present study, the microbial community structure in an intermittently aerated submerged membrane bioreactor treating domestic wastewater was observed using the respiratory quinone profiles. The effects of different time interval for the aerobic and anoxic period on microbial community structure were examined with 60/90 min (Step 1) and 90/60 min (Step 2) as anoxic/aerobic periods. There was an observable slight difference in microbial community structure between Step 1 and Step 2 in the submerged membrane bioreactor. The dominant quinone types for Step 1 at both anoxic and aerobic conditions were UQ-8 followed by UQ-10 and MK-6, but those for Step 2 were UQ-8, MK-6 and MK-10(H4). The microbial diversity of Step 1 and Step 2 based on the composition of all quinones was 10.6-11.7 and 13.3-13.0 for anoxic and aerobic conditions, respectively. The present results suggest that the introduction of intermittent aeration into the submerged membrane bioreactor has little influence on the bacterial community structure.