TREATMENT OF CYAN-CONTAINING WASTE WATER AND CHROMIUM-CONTAINING WASTE WATER

摘要

PURPOSE:To treat efficiently and simultaneously cyan-contg. waste water by decomposing first and easily decomposable cyan in the cyan-contg. waste water then reducing hexavalent chromium and insolubilizing the hardly decomposable cyan then subjecting the waste water to codeposition and solid-liquid sepn. CONSTITUTION:The cyan-contg. waste water is treated by an alkali chlorine method to decompose the easily decomposable cyan. The waste water is then subjected to a reducing treatment in the presence of copper ions to reduce the hexavalent chromium to tervalent chromium and to insolubilize the hardly decomposable cyan. The pH of the waste water is thereafter adjusted to 7-9 and the tervalent chromium is codeposited with heavy metals and is subjected to the solid-liquid sepn. together with the insoluble cyan compd. The cyan-contg. waste water is thus efficiently and simultaneously treated and the solid-liquid sepn. is made possible at low pH.