Treatment methods for wastewater containing sodium fluoride

Abstract

A method for treating wastewater containing sodium fluoride involves adding aluminum salts to the wastewater to precipitate cryolite, followed by solid-liquid separation to separate the cryolite from the treated water. The pH for cryolite precipitation is set to 5–7, particularly 5–6. The aluminum salts are added such that the aluminum concentration in the treated water is below 500 mg / L (Al), particularly 10–200 mg / L. After cryolite precipitation, a polymer coagulant is added for coagulation treatment, followed by the solid-liquid separation. A portion of the solid-liquid separated cryolite is returned upstream.

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