Recovery of silver from photographic processor effluents

摘要

Wash-off effluent from a photographic film processor is desilvered by a continuous process, employing the following sequence of steps: 1. Addition of anti-foaming agent. 2. Acidification. 3. Chemical reduction of ionic silver to metallic silver by sodium borohydride in alkaline solution. 4. Addition of one of more fluocculants. 5. Passage through hold-up tank to allow time for flow formation. 6. Filtration through automatic gravity filtration device or its equivalent. An apparatus for the treatment process is also provided.