Waste Disposal Study. Evaluation of Methods to Recover Reusable Chemicals from Evaporated Photowastes.
Final rept. May 74-Nov 75,
CPAC INC LEICESTER N Y POLLUTION ABATEMENT DIV
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The feasibility of recovering usable chemicals from evaporated photoprocessing wastes was studied. About 50-70 of the evaporated waste consists of sodium thiosulfate and sodium sulfite. Recovery of thiosulfate and sulfite was achieved via solubilization and either a combination of crystallization and subsequent barium precipitation of these desired sulfur salts, or direct barium precipitation. The barium salts could then be converted to the soluble sodium thiosulfate and sodium sulfite by action of sodium carbonate. Recovery efficiencies to 90 were achieved. Maximum yields were obtained when the sodium thiosulfate was greater than 50 of the waste, and water was used as the solubilizing agent. For wastes containing quantities lower than this concentrate, sodium hydroxide was the solvent of choice. The latter allowed separation of sulfite from thiosulfate.
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