Dominant bacteria correlated with elimination of sludge in an innovative reactor

This study was conducted to identify bacteria responsible for the elimination of sludge in an innovative gravel contact oxidation reactor (GCOR) and a conventional activated sludge reactor (ASR). Fluorescent in situ hybridization revealed that α-, β-, γ- and ε-Proteobacteria and Bacteroidetes were present in both reactors. In the GCOR, γ-Proteobacteria accounted for 13% of the biofilm biomass on the carrier, while α-, ε- and β-Proteobacteria accounted for 12%. However, the predominant bacteria in the pores of the carrier in the GCOR were Bacteroidetes (18%), ε-Proteobacteria (13%), β- and α-Proteobacteria (10%) and γ-Proteobacteria (9%). Conversely, β-Proteobacteria (18%), Bacteroidetes (13%), α- and γ-Proteobacteria (12%) and ε-Proteobacteria (5%) dominated the sediment community of the ASR.