Low removal rate for total nitrogen (TN) is the main limitation of a membrane bioreactor (MBR). The effects of intermittent aeration on the removal of TN and the microbial community structure of activated sludge from a submerged membrane bioreactor (SMBR) operating at three different aeration on/off times (run 1, continuous aeration; run 2, 60/60 min aeration on/off time; and run 3, 60/75 min aeration on/off time) were studied. The results showed that the removal rates for TN under different operation conditions were 26.2% (run 1), 59.5% (run 2) and 70.7% (run 3), respectively, and significant improvements were achieved. Monounsaturated phospholipid fatty acids (PLFAs) and saturated PLFAs were dominant PLFA types in activated sludge, followed by branched PLFAs; cyclopropane fatty acid were relatively small in amount. The highest ratio of the characteristic fatty acid representing the abundance of bacteria in activated sludge was found in run 2. Aerobic prokaryotes were the predominant groups under all three operation conditions, followed by the anaerobic bacteria and the Gram-positive bacteria group; sulphate-reducing bacteria (SRB) and other anaerobic bacteria occupied the lowest proportion. Intermittent aeration can be used as a possible means to improve the treatment performance in an MBR.
Chang, Jun-Jun; Liang, Wei; Xiao, En-Rong; Wu, Zhen-Bin.Effect of intermittent aeration on the microbial community structure of activated sludge in a submerged membrane bioreactor,WATER AND ENVIRONMENT JOURNAL,2011,25(2):214-218