Performance and Spatial Distribution of Functional Bacteria under Low-Temperature Stress in Biofilm Systems for Polluted Source Water Pretreatment

Performance of biofilm reactors for polluted source water pretreatment is usually limited under low-temperature stress in cold winter, and two biofilm reactors were built up for studying performance promotion and spatial distribution of functional bacteria. Experimental results showed that unstable but enhanced pollutants removal was observed in biofilm reactors under low-temperature stress of 8.6 +/- 1.8 degrees C. Proteobacteria was dominant as functional bacteria for nitrogen and organics removal with the maximum relative abundance (RA) values of 30.7-51.7%. Gammaproteobacteria and Alphaproteobacteria were dominant at any spatial locations in blank ESM reactor with RA of 22.8-28.6% and 10.9-14.6%, respectively. The pre-cultured bacteria affected the bacterial distribution under low-temperature stress. Gammaproteobacteria with RA of 14.5% were dominant in the end and Alphaproteobacteria dominant in other locations in precoated ESM reactor with RAs of 12.5-12.9%. Biofilm systems faced the potential risks including Cyanobacteria (0.9-18.62%) and potential bacterial pathogens (PBP) (10.05-12.43%) under low-temperature stress. Fortunately, potential cyanotoxins production genus Planktothrix of Cyanobacteria was gradually decreased and hardly observed at the end of reactors.