Process for controlling pollution and contamination in the electrodeposition of paint

Claim 1

In a process for controlling pollution and contamination in the electrodeposition of paint from an aqueous paint bath on articles in which waste water including paint drippings from such articles and water used to wash said articles after they have been painted contains negatively charged paint solids which are tacky, the improvement which consists essentially of adding to said waste water a quantity of an acidic anionic silica sol and a water dispersible coagulating anionic or non-ionic polymer sufficient to reduce the tackiness of the paint solids in said waste water and sufficient to condition said solids so that they can be separated from said water, said water dispersible polymer having an average molecular weight of at least 5000 and having a linear carbon chain to which is attached a plurality of groups selected from the group consisting of anionic groups and non-ionic groups, the proportions of said silica sol corresponding to 500 to 2000 parts by weight of a silica sol containing 30% to 50% by weight SiO 2 per million parts of said waste water and the proportions of said polymer corresponding to 0.5 to 15 parts by weight per million parts of said waste water, and separating said solids from the water.