Abstract: The Emission Standard of Pollutants for Petroleum Refining Industry (GB31570-2015) sets clear control targets for total nitrogen. One petrochemical company carried out standard upgrading before the new standard was issued. On the basis of the original process, facilities involving denitrification biological filter and sand filter tank were added. The reverse osmosis concentrated water was treated by ozone oxidation, denitrification, air floatation, sand filtration and activated carbon. After such revamp, the operation has been stable; the quality of effluent has been good and the effluent discharge of sewage has reached the standard steadily for five consecutive years. The experience of such revamp after standard upgrading can provide reference for other enterprises.

Key words: reverse osmosis concentrated water, denitrification, sand filtration, refining sewage