PROCESS AND APPARATUS FOR TREATING WASTE WATER IN CATIONIC ELECTROCOATING

摘要

A process for treating waste water, which comprises feeding waste water from a final water washing tank of a final water washing step in a cationic electrocoating to a receiving-concentration tank, feeding the waste water from the receiving-concentration tank to a membrane separation unit, thereby separating the waste water into a filtrate and a concentrated solution, and continuously recovering the separated filtrate for reuse in the final water washing step, characterized by continuously detecting the pH of the filtrate, continuously injecting and acid into the waste water, thereby keeping the pH of the filtrate to a predetermined range, and adjusting the pH of the waste water.