Effluent purification in car body coating - by adsorption of degreasing solvents on lime pptd. phosphates

摘要

Rinsing baths contg. degreasing solvents are treated by adding >=5 ppm of polyelectrolytes e.g. Fe or Al sulphates or chlorides as flocculants and 0.5 g/litre of lime or baryta to supply a cation which forms insol. phosphates and sulphates at pH 7-10 (9-9.5) and maintaining the ppt. in suspension to allow it to adsorb the degreasing agent. Content of degreasing solvents is reduced from 225 m/litre and suspended materials from 50 mg/litre to 10-2 mg/litre and nil respectively. The treated effluent is odourless.