METHOD FOR TREATING WASTE SALINE WATER PRODUCED IN PRODUCTION PROCESS OF DIPHENYLMETHANE DIISOCYANATE (MDI)

摘要

A method for treating waste saline water produced in production process of diphenylmethane diisocyanate (MDI) involves the following steps: (1) quickly mixing the waste saline water and fresh extractant in a super-gravity rotating bed, and introducing separated waste saline water and fresh extractant into an extraction tower to conduct counter-current extraction after phase separation; (2) introducing the waste saline water discharged from step (1) into a steam stripping tower to conduct steam stripping; (3) transmitting the waste saline water discharged from step (2) into an oxidation reactor together with a chemical oxidant, and introducing air into the reactor to conduct aeration; and (4) sending the waste saline water discharged from step (3) into an absorption tower for an absorption treatment. The method can reduce total organic carbon (TOC) of treated saline water to be less than 8 ppm and total nitrogen (TN) to be less than 2.5 ppm, and recover sodium chloride and water from the waste saline water.