| 摘要 |
PROBLEM TO BE SOLVED: To efficiently treat a used processing solution containing a metal and various chemicals after the processing of a photographic film or the like at a low cost without adversely affecting the environment and a living thing. SOLUTION: A used photographic solution is treated under an acidic condition of <=pH 2, preferably pH 1-2 with a solution prepared by dissolving weathered granite in a mineral acid, preferably sulfuric acid to carry out acid treatment and then the solution is treated under an alkaline condition of pH 7.5-8.5 with calcium carbonate 14 of aragonite to carry out alkali treatment. In the acid treatment, bleaching powder 12 is preferably added and treatment is preferably carried out under aeration while blowing ozone.
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