Effects of carbon sources on sludge performance and microbial community for 4-chlorophenol wastewater treatment in sequencing batch reactors

Considering carbon sources are often supplied to satisfy the removal of high nitrogen and refractory pollutants in industrial wastewater, two sequencing batch reactors (SBRs) were used in this study to treat 1.5 ± 0.5 mg/L 4-chlorophenol (4-CP) wastewater containing ammonium nitrogen and phosphate with different carbon sources. The favorable removal efficiencies of influent COD, NH4+-N, PO43−-P, and 4-CP suggested that the both SBRs were not influenced by supplying dissolved starch and sodium acetate, respectively. The phyla Proteobacteria and Bacteroidetes were dominant in both SBRs, while the dominant phylum Candidatus Saccharibacteria was only existed in SBR with carbon source of dissolved starch. The relative abundance of bacterial communities had significant differences at class, family, and order level in both SBRs. And the mutually dominant genus in both SBRs was only Gemmobacter, which was first found in 4-CP wastewater treatment. The changed extracellular polymeric substances (EPS) were related with microbial communities.