Oxygen-limited aeration for relieving the impact of phenolic compounds in anaerobic treatment of coal gasification wastewater

Anaerobic digestion is an efficient tool for improving aerobic biodegradability of coal gasification wastewater, but the shock loading usually results in a failed performance of the anaerobic process. The oxygen-limited aeration was conducted to handle the impact of coal gasification wastewater in an anaerobic expanded-bed GAC reactor. Results indicated that the oxygen-limited aeration of 0-0.5 mgO(2)/L could shorten the recovery time from 23 to 11 days under natural condition, and the addition of 1 g/L PAC could reduce the recovery time to 14 days. The corresponding removal efficiencies of COD and phenolic compounds could increase to above 60 and 50%, respectively. The phenol utilization rates of sludge reached 83.9 +/- 5.7 mg phenol/(g VSS d) after recovery of reactor performance by using oxygen-limited aeration, and only 70.4 +/- 3.8 mg phenol/(g VSS d) by using natural recovery and 65.2 +/- 5.9 mg phenol/(g VSS d) by using PAC addition. The recovery strategy of oxygen-limited aeration might be helpful to relieve the inhibitory effect of phenolic compounds and restore metabolic activity of anaerobic bacteria. (C) 2014 Elsevier Ltd. All rights reserved.