| 摘要 |
PROBLEM TO BE SOLVED: To remove iron of a complex form especially from a discharge liquid by a method wherein the discharge liquid is successively treated with silicate, Ca(OH)2 , base, hydrotalcite, and a coagulant, and an obtained mixture is filtered by decanting. SOLUTION: A aqueous discharge liquid generated by photographic treatment is successively treated with silicate and hydrotalcite, decanted, and filtered. A coagulant or a combination of Ca(OH)2 /base/coagulant is used according to a mode of execution. In this case, the discharge liquid is successively treated with silicate, Ca(OH)2 , hydrotalcite, base, and a coagulant, decanted, and filtered. Herein, the silicate to be used is silicate of an alkali metal, for example, sodium silicate. The coagulant is, for example, an organic derivative of poly(ethyleneamine) or the like, or an inorganic derivative of alum or the like, or a derivative of natural products such as starch or the like. The base may be organic or inorganic one. The hydrotalcite may be naturally originating one or that manufactured by chemical synthesis.
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