Abstract
Federal, state and municipal regulations on the disposal of industrial waste water have stimulated much photographic industry activity where chemical and mechanical methods must be devised to comply with the regulations. Several systems are in use for treating the major problems of photographic waste water. The bleach solution is one of the most troublesome materials to treat because of the presence of heavy metals or cyanides. The concentration of these substances must be reduced to a level of 0.1 ppm. Work is described that has been done to develop and test a bleach formula that contains no chromium, iron or cyanides. A copper halide bleach was found to be attractive because under current regulations permissible levels for copper are 15 times greater than for cyanide or hexavalent chromium. Either cupric bromide or cupric chloride could be used, and the latter was selected for testing because it has a cost advantage. A 21-g/I concentration was found to give bleaching times equivalent to SR27. The replenishing rate is 654 liters per million feet of 35mm Eastman color positive film (5381).
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