New technology for waste water from water-washed paint spray booths

Abstract

A new procedure for treatment of waste water from water-washed paint spray booths was developed. This technology has been established on a modular basis. All process units have a new design and were developed in our previous projects. The treatment included chemical coagulation in a special fixed-bed reactor, suspended solids separation in deep-bed filter with floating media, and adsorption. Experiments were realized both on the bench and pilot-plant scale. Some commercial coagulants and flocculants were used in chemical treatment. Jar-tests were performed to select reactants and determine optimum doses. Pilot-plant tests were conducted with aluminium sulphate as coagulant (optimum dose 160–180 mgl−1) and polyacrylamide as flocculant (optimum 1–1.5 mgl−1). Domestic bauxite, perlite, zeolite and activated carbon were used as adsorbents in laboratory tests. Expanded polystyrene granules were used as packing material in the multipurpose reactor and deep-bed filter. The following characteristics of expanded polystyrene and adsorbents were measured: main diameter, effective diameter, uniformity, bulk density, density, bed porosity (on the basis of sieve analysis), permeability, zeta-potential, microstructure, and surface morphology. The efficiency of each step was estimated on the basis of COD values and suspended solid content in the influent and effluent. The efficiency of chemical coagulation step after deep-bed filtration was from 30 to 72%, whereas total efficiency, including adsorption, was from 66 to 86%, all estimated on the basis of COD values. © Publications Division Selper Ltd., 1996.