METHOD OF TREATING RARE EARTH ELEMENT-CONTAINING WASTE WATER

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PROBLEM TO BE SOLVED : To reduce the usage amount of waste water treating chemicals, to reduce produced sludge amount and to cut down plant equipment by mixing rare earth element-containing waste water with another waste water and treating the mixed waste water. SOLUTION : In the method of treating the rare earth element-containing waste water, the rare earth element-containing waste water is mixed with another waste water including at least one component among fluorine, phosphorus and arsenic and the mixed waste water is subjected to solid-liquid separation. Hydroxide and carbonate of rare earth elements have relatively high solubility and, therefore, when there are phosphate ions, fluoride ions, arsenate ions, arsenite ions or the like, hydroxide ions and carbonate ions are liberated and phosphate ions, fluoride ions, arsenate ions, arsenite ions and the like are fixed. By mixing the rare earth element-containing waste water with another waste water and treating the mixed waste water, the usage amount of chemicals can be reduced and the produced sludge amount can be reduced. COPYRIGHT : (C)2006, JPO&NCIPI