Process for concentrating lacquer overspray

摘要

Process for concentrating a mixt. of wash water and overspray from a painting chamber comprises preconcentrating the mixt. (2) in an ultrafiltration unit (3) to obtain a retentate (4) and a permeate (5) contg. low mol. wt. component; passing the ultrafiltration permeate (5) and a recycled nanofiltration permeate (11) to a reverse osmosis unit (6) to obtain a retentate (7) and a practically pure water permeate (8); recycling the permeate (8) to the wash water circuit; and passing the combined ultrafiltration and reverse osmosis retentates to a nanofiltration unit (9) to obtain a permeate (11) and a retentate (10) wherein the retentate largely corresponds in compsn. and concn. to the water-based lacquer used for spray painting.