The biochemical sewage treatment unit of the project is designed to treat the ammonia evaporation wastewater generated by the gas purification system and the process wastewater generated in the process of chemical production and refining. The designed treatment capacity of the project is 135 m3/h, and the annual treatment of coking wastewater is more than 1 million tons. The process adopts A/A/O internal cycle biological nitrogen removal technology, which can effectively degrade ammonia nitrogen, COD and phenol cyanogen pollutants in coking wastewater. In 2015, the upgrading project was completed, and new units such as remove total nitrogen and reduce total cyanide were added.

Since 2016, ONCE has supplied customized coking wastewater advanced treatment series agents for this project to achieve the advanced treatment of COD and total cyanide. After advanced treatment, the water quality reached the straight discharge standard. Indicators before and after advanced treatment are shown in the following table.

Table 1 Indicators of coking wastewater before and after advanced treatment

Biochemical reaction pond situation

The effluent of sedimentation tank