Abstract: It is of great significance for the development of coal chemical industry to solve the standard treatment of high hardness and high ammonia nitrogen wastewater produced from coal gasification for hydrogen production. According to the characteristics of sewage, the combined process of chemical hardness reduction with biological decarbonization and nitrogen removal was adopted in a refinery. The results of unit running indicated that the average removal rates of COD, NH3-N, total nitrogen were stable at above 90.8%, 98.5%, 92.9%, respectively, which could meet the requirement of special discharge limit in the national standard “Emission standard of pollutants for petroleum refining industry(GB 31570—2015)”. The long-term stable operation of the designed water load of 140% has been realized. The experience can be used for reference in similar wastewater treatment.

Key words: coal gasification wastewater, hardness, ammonia nitrogen, hardness reduction, biological decarbonization and denitrification