Process for treating rinsing water used for phosphating metallic surfaces comprises subjecting the rinsing water to membrane separation, returning the concentrate to the bath, and demineralizing the permeate and returning as rinsing water

摘要

Process for treating rinsing water comprises subjecting the rinsing water to a membrane separation process and returning the concentrate of the process to the phosphating bath. The permeate of the membrane separation process is demineralized and returned as rinsing water. Preferred Features: The membrane separation process is a nanofiltration or reverse osmosis. Before membrane separation, the rinsing water is subjected to mechanical filtration. Before membrane separation, the pH of the rinsing water is reduced to the level in the phosphating bath.