Comparison of Activity between Attached Bacteria and Suspended Bacteria in Drinking Water Distribution System

Under the controlled laboratory conditions,the rotating annular bioreactor(RAB) intermittently operated was used to investigate the activities of heterotrophic bacteria attached to biofilm and suspended bacteria in water after the biofilm on coupon was stabilized.The results show that the AOC concentration decreases gradually with the prolongation of operation time,from 64 μg/L to 28 μg/L(calculated as acetic acid carbon) after a 24-h retention period.The amounts of suspended bacteria and attached bacteria increase and subsequently decrease with operation,and the former fluctuation is more significant.During the first 12 h,the activities of suspended bacteria and attached bacteria increase.After the 12 h,the activity of suspended bacteria decreases rapidly while the activity of attached bacteria decreases slightly,which suggests that the attached bacteria have higher adaptability to the environment than the suspended bacteria.