p-Cresol mineralization and bacterial population dynamics in a nitrifying sequential batch reactor

Area of Science:

• Environmental microbiology
• Bioremediation technologies
• Wastewater treatment

Background:

• p-Cresol is a common industrial pollutant.
• Nitrifying microbial communities are crucial for wastewater treatment.
• Simultaneous removal of p-cresol and ammonium is a challenge.

Purpose of the Study:

• To evaluate the capacity of nitrifying sludge to oxidize p-cresol.
• To investigate the microbial community dynamics during p-cresol degradation.
• To assess the impact of p-cresol on nitrification performance.

Main Methods:

• Sequential Batch Reactor (SBR) operation.
• Denaturing Gradient Gel Electrophoresis (DGGE) for microbial community analysis.
• Monitoring of ammonium consumption and nitrate production.

Main Results:

• p-Cresol was transformed to p-hydroxybenzaldehyde and p-hydroxybenzoate, then mineralized.
• Specific p-cresol consumption rates increased over time.
• Nitrifying sludge demonstrated high stability and efficiency in removing both ammonium and p-cresol.
• Variovorax paradoxus and Thauera mechernichensis were identified as potential key species.

Conclusions:

• Nitrifying SBRs can effectively and simultaneously remove ammonium and p-cresol.
• The microbial community structure remained stable, contributing to robust performance.
• This approach offers a stable and efficient method for treating wastewater contaminated with p-cresol and ammonium.