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

Area of Science:

• Environmental microbiology
• Bioreactor engineering
• Wastewater treatment

Background:

• Industrial wastewater often contains toxic organic pollutants like 4-chlorophenol (4-CP).
• The impact of these pollutants on biological treatment systems, specifically sludge characteristics, is a critical concern.
• Understanding these effects is vital for optimizing wastewater treatment processes.

Purpose of the Study:

• To investigate the effects of varying 4-chlorophenol (4-CP) influent concentrations on sludge toxicity, enzymatic activity, and microbial community structure in a sequencing batch bioreactor (SBR).
• To establish correlations between 4-CP loads and these sludge parameters.
• To provide theoretical support for mitigating sludge toxicity in industrial wastewater treatment.

Main Methods:

• Utilized two sequencing batch bioreactors (SBRs): one acclimated to 4-CP and a control without 4-CP.
• Investigated influent 4-CP concentrations from 10 to 100 mg L^-1.
• Assessed sludge toxicity, enzymatic activity, and microbial community composition.

Main Results:

• Sludge toxicity showed a positive correlation with increasing influent 4-CP concentrations.
• Enzymatic activity was stimulated by long-term 4-CP acclimation, correlating positively with 4-CP loads and sludge toxicity.
• Microbial diversity initially increased then decreased with rising 4-CP loads, while microbial community similarity to the control decreased.

Conclusions:

• Wastewater treatment sludge toxicity increases with 4-CP concentration.
• Enzymatic activity and microbial community structure are significantly affected by 4-CP exposure.
• Findings offer insights for managing sludge toxicity in industrial wastewater treatment plants.