Inhibition and Recovery of Nitrification during the Process of Sludge Reduction Induced by a Metabolic Uncoupler, 2,6-Dichlorophenol (2,6-DCP)

Abstract

2,6-DCP was found to be an efficient metabolic uncoupler to reduce sludge production. 20mg/L 2,6-DCP could reduce sludge production about 34.62%, however, it also affected nitrification seriously, the nitrification inhibition was about 76.17% compared to control. Environmental factors, temperature and pH, were varied to repair nitrification. The nitrification inhibition was decreased to 45.7% at 28±1 ◦C and pH=8.5±0.2. Nitrification inhabitation was further decreased to 30% when the 2,6-DCP concentration reduced to 10 mg/L, the sludge reduction also decreased to17.9%. The 30-day operation data indicated that 10mg/L 2,6-DCP can also effectively reduced the sludge production about 17.9% with the COD removal efficiency decreased about 6.99% and nitrification inhabitation was about 30.91%. It shouldn’t only consider the sludge reduction when selecting the concentration of metabolic uncoupler. The application of metabolic uncoupler for sludge reduction should be cautious and need further study.