2-Chlorophenol consumption by cometabolism in nitrifying SBR reactors

Area of Science:

• Environmental microbiology
• Wastewater treatment
• Bioremediation

Background:

• 2-chlorophenol (2-CP) is a recalcitrant pollutant requiring effective degradation methods.
• Nitrifying sludge possesses microbial communities capable of cometabolic degradation.
• Sequential Batch Reactors (SBRs) are commonly used for biological wastewater treatment.

Purpose of the Study:

• To evaluate the cometabolic consumption of 2-CP by nitrifying sludge in SBRs.
• To investigate the effect of varying ammonium concentrations on 2-CP degradation rates.
• To elucidate the role of the ammonium monooxygenase (AMO) enzyme in 2-CP cometabolism.

Main Methods:

• Operation of two SBR reactors with controlled 2-CP and varying ammonium concentrations.
• Monitoring of ammonium and 2-CP consumption efficiencies and production yields.
• Batch assays using allylthiourea to inhibit AMO and assess its involvement in 2-CP degradation.

Main Results:

• Complete nitrification (>99% efficiency) and nitrate production (0.93-0.99 yield) were achieved within 14 days.
• Complete 2-CP consumption occurred within 7 days, with consumption rates increasing significantly with higher ammonium levels.
• Batch assays demonstrated AMO enzyme participation in 2-CP consumption, increasing from 34% to 53% over operating cycles.

Conclusions:

• High ammonium concentrations significantly enhance the cometabolic consumption of 2-CP by nitrifying sludge.
• The ammonium monooxygenase (AMO) enzyme plays a crucial role in the degradation of 2-CP.
• Nitrifying sludge in SBR systems offers a promising strategy for the bioremediation of recalcitrant compounds like 2-CP.