Biological treatment process for coal gas wastewater of Lurgi gasifier

The invention discloses a biological treatment process for coal gas wastewater of a Lurgi gasifier, which relates to a biological treatment process for wastewater and solves the problems of poor effluent effect, substandard of effluent discharge, high cost and poor stability of effluent quality existing in the treatment of the coal gas wastewater of a traditional Lurgi gasifier. The process comprises the following steps that: firstly, wastewater is extracted with an extracting agent and then is pretreated by adopting a steam stripping-ammonia evaporation process; secondly, the treated wastewater enters an adjusting tank, then enters a hydrolyzation and acidification tower, enters an external circulation (EC) anaerobic tower and finally flows into a two-stage contact type oxidation pond; thirdly, effluent of the two-stage contact type oxidation pond flows into a coagulative precipitation tank; and fourthly, effluent of the coagulative precipitation tank flows into a semicoke adsorption filter pond and the biological treatment of the coal gas wastewater of the Lurgi gasifier is finished. The process has the advantages of impact resistance, strong load capability, lower treatment cost, stable effluent quality and good effluent effect, can meet the national level of discharging standard and provide powerful guarantee for healthy development of the coal gas industry.