Abstract: A large amount of cyanide containing wastewater was produced during the operation of POX unit of a refinery and affected the normal operation of the downstream wastewater treatment plant. Especially when processing high-nitrogen crude oil in atmospheric distillation unit, the amount of cyanide in the wastewater increased significantly, and the discharge of waste water exceeds the internal control index, which seriously restricted the crude oil purchase of the petro-chemical enterprise. In order to meet environmental requirements and remove the constraints for crude oil purchase, this paper introduced the advantages and disadvantages of three kinds of cyanide removal technologies: (i) catalytic oxidation and hydrolysis at high temperature and high pressure, (ii) elec-tro-catalytic oxidation, and (iii) chemical addition precipitation.

Key words: gasification, waste water, cyanide, catalyticoxidation and hydrolysis at high temperature and high pressure, electrocatalytic oxidation, chemical addition precipitation