Advanced treatment of biologically pretreated coal gasification wastewater using a novel anoxic moving bed biofilm reactor (ANMBBR)–biological aerated filter (BAF) system

• The ANMBBR–BAF had efficient capability of treating biologically pretreated CGW.
• HRT and R strongly affected the performance of the system.
• The SBNR had stable and efficient capability of TN removal even high toxic loading.
• The ANMBBR removed toxic and refractory compounds, which was beneficial for SBNR.

A novel system integrating anoxic moving bed biofilm reactor (ANMBBR) and biological aerated filter (BAF) with short-cut biological nitrogen removal (SBNR) process was investigated as advanced treatment of real biologically pretreated coal gasification wastewater (CGW). The results showed the system had efficient capacity of degradation of pollutants especially nitrogen removal. The best performance was obtained at hydraulic residence times of 12 h and nitrite recycling ratios of 200%. The removal efficiencies of COD, total organic carbon, NH4+-N, total phenols and total nitrogen (TN) were 74.6%, 70.0%, 85.0%, 92.7% and 72.3%, the corresponding effluent concentrations were 35.1, 18.0, 4.8, 2.2 and 13.6 mg/L, respectively. Compared with traditional A2/O process, the system had high performance of NH4+-N and TN removal, especially under the high toxic loading. Moreover, ANMBBR played a key role in eliminating toxicity and degrading refractory compounds, which was beneficial to improve biodegradability of raw wastewater for SBNR process.