Post-treatment of Coal Gasification Wastewater Using a Moving Bed Biofilm Reactor in Present of Methanol

Laboratory scale moving bed biofilm reactor (MBBR) was used to treat effluent from post-denitriflcation process in full-scale coal gasification wastewater treatment plant. Methanol was added into the effluent from post-denitriflcation to investigate the effect of surplus methanol on reactor performance. The average effluent COD, NH₄-N and NO₂-N concentrations were 145.14, 11.88 and 0.22 mg/L for blank reactor (without adding methanol), respectively. The performance of MBBR was little affected when the surplus methanol concentration was 54 mg/L and after acclimation the average effluent COD, NH₄-N and NO₂-N concentrations were 137.35, 15.2 and 0.44 mg/L, respectively. With the increase of methanol concentration from 90 to 180 mg/L, the effluent NH₄-N concentrations increased from 20.31 to 29.18 mg/L. The results indicated that surplus methanol concentration in the effluent from post-denitrification must be controlled below 54 mg/L to avoid negative effect on the post-treatment process.