The invention provides methods and compositions for a composition and/or a method for treating impurities in a circulating water system. The circulating water system impurities may be oversprayed paint in paint spray booth applications. The composition includes an aqueous solution of a cationized starch, a polybasic aluminum salt such as aluminum chlorohydrate or polyaluminum chloride and a solution of a medium to high MW aqueous flocculant. The composition is particularly useful when added to recirculating scrubber water in paint spray booths for effectively treating both water based and solvent based paints.