Treatment of Lurgi coal gasification wastewater in external circulation anaerobic process

To enhance the anaerobic treatability of Lurgi coal gasification wastewater(LCGW), full-scale study on external circulation anaerobic treatment of LCGW was carried out and the effects of influent concentration, hydraulic retention time and methanol addition on the treatment efficiency were studied. Results indicated that the treatment efficiency of LCGW was very low and the removal efficiency of COD and total phenols were 18.5% and 20.3% with the influent COD and total phenols of 1100 mg/L and 210 mg/L, respectively. When the influent COD increased to 2100 mg/L, the removal efficiencies of COD and total phenols were 18.5% and 20.3% respectively. Prolonging the hydraulic retention time from 24 h to 48 h, the COD and total phenols removal increased slightly. The COD and total phenols removal increased to 40.7% and 35.2% respectively with the methanol addition of 200-500 mgCOD/L. The methanol addition can enhance anaerobic treatment efficiency obviously, but the effect of dilution or prolonged hydraulic retention time is slight.