Kinetic characteristics and bacterial structures in biofilm reactors with pre-cultured biofilm for source water pretreatment

The growth and accumulation of functional bacteria were limited due to the deficiency of substrates in biofilm reactors for source water pretreatment. In this study, pre-cultured biofilm (PCB) formed on different carriers was used to treat oligotrophic source water, and the kinetic characteristics and bacterial structures was evaluated under realistic conditions. Experimental results showed that PCB formed under substrate-enhanced conditions decreased substrate affinity of biofilm, but effectively improved the operation performance of biofilm reactors. In particularly, biofilm formed on elastic stereo media had the lowest apparent half-saturation coefficient (Ks) for substrates, which was more easily to accommodate oligotrophic niche. Interestingly, biodiversity of biofilm was obviously increased after long-term exposure to oligotrophic niche, and decreased functional bacteria were replaced by others with similar function. Basically, Proteobacteria and Planctomycetes were dominant in biofilm samples under both substrate-enhanced and oligotrophic conditions. (C) 2017 Elsevier Ltd. All rights reserved.