Method for the purification of waste water containing silver

摘要

A process is disclosed for the purification of waste water containing a silver compound, comprising the steps of (1) adding to said waste water a salt of a poly(guanidine) or poly(biguanidine) polymer (2) adding a flocculant, and (3) filtrating the formed flocculate. The invention is particularly suitable for the removal of silver from the effluent of a photographic processor, and more specifically the effluent of a processor of wash-off materials, said effluent also containing gelatin. A most preferred poly(guanidine) compound is poly(hexamethyleneguanidine) hydrochloride.