Spray painting of automobile bodies, truck engines, appliances, and other industrial goods is customarily carried out in enclosed areas called paint spray booths (PSB). The units to be painted generally pass through the work area while an air-flow makes the over-sprayed paint contact either the sump water or the spray from the water curtain. The air is scrubbed with re-circulated water at the water curtain, passes through the mist eliminators, and is removed by an exhaust fan.

Since roughly one-half of all paint sprayed does not reach its intended article, a significant concentration of paint builds in the system and agglomeration can occur. The resultant mass is a sticky, tacky material which can plug the mist eliminators, shower heads, and even recirculating pumps. When this happens, scrubbing efficiency decreases leading to potentially hazardous conditions of unchecked paint emissions being discharged into the atmosphere.

This process involves other problems. These tacky organic deposits are subject to anaerobic bacterial growth which generates corrosion and odor problems. In addition, the paint solids which are re-circulated can form suspensions in the water. They remain tacky can create expensive separation and disposal problems. These problems show, therefore, the desirability to treat PSB water systems so as to reduce or prevent as much as possible, the agglomeration and deposition of over-sprayed paint on critical PSB operation parts; to render the resultant sludge non-tacky and easily removable; and to provide a water quality such that it can be recycled for use in the system.