Effects of 4-chlorophenol toxicity on sludge performance and microbial community in sequencing batch reactors.

In this study, the effects of 4-chlorophenol (4-CP) influent concentrations ranging from 10 to 100 mg L⁻¹ on sludge toxicity, enzymatic activity and microbial community, along with their correlations, were investigated in a sequencing batch bioreactor (SBR), which was defined as the acclimated SBR. Another SBR was set as a control group that did not receive the influent 4-CP. The results showed that the sludge toxicity increased as the influent 4-CP increased, exhibiting a positive correlation with 4-CP loads. The enzymatic activity was stimulated after long-term acclimation with 4-CP and was positively related to the 4-CP loads and sludge toxicity. During the stable operational stages of the acclimated SBR, the microbial diversity first increased and then decreased as the 4-CP loads increased, while the similarity of the microbial community between the acclimated and control SBRs decreased with increasing 4-CP loads. The aim of this study is to provide theoretical support for reducing sludge toxicity in industrial wastewater treatment. [ABSTRACT FROM AUTHOR]