| A laboratory-scale submerged anaerobic-anoxic-oxic membrane bioreactor (A1/A2/O-MBR) system was used to treat real coke wastewater and operated continuously for 160 d with complete sludge retention. Pollutants removal performance of the system was investigated through long-term operation. The characteristics of dissolved organic matters (DOMs) in influent and effluent coke wastewater were analyzed using hydrophilic/hydrophobic fractionation, and further discussed based on fluorescence excitation-emission-matrix (EEM). The results showed that A1/A2/O-MBR system could stably remove 88.0%±1.6% of COD, >99.9% of volatile phenol, 99.4%±0.2% of turbidity, and 98.3%±1.9% of NH+4-N, with individual average effluent concentrations of 249 mg/L±44 mg/L, 0.18 mg/L±0.05 mg/L，1.0 NTU±0.2 NTU and 4.1 mg/L±4.3 mg/L, respectively; moreover, the maximum TN removal rate also reached 74.9%. During the whole operation period, the MLVSS/MLSS appeared to be constant as 90.2%±1.0% and no inorganic matters accumulation occurred. The observed sludge production (MLVSS/COD) decreased with time and stabilized at 0.035 kg/kg. DOMs in coke wastewater were fractionated as hydrophobic acids (HOA), hydrophobic neutrals (HON), hydrophobic bases (HOB) and hydrophilic substances (HIS); HOA was found to be the most abundant constituent in terms of DOC and color intensity both in influent and effluent, which accounted for 70% and 67% of total DOC, and 75% and 76% of total color intensity, respectively. Humic-like substances were suggested to be the major refractory organic and color-causing compounds coke wastewater effluent according to EEM analysis. |
