METHOD FOR RECOVERING WATER AND METALS FROM PLATING WASTEWATER RESULTING FROM WASHING

摘要

A method for water and metal recovery from a plating wastewater resulting from washing is disclosed with which water and metals are efficiently recovered from the plating wastewater, the method comprising an iron insolubilization step in which the pH of the plating wastewater is regulated to 3-6 in the presence of an oxidizing agent to oxidize divalent iron ions contained in the liquid to trivalent iron ions and precipitate an iron hydroxide, a solid-liquid separation step in which the water treated in the iron insolubilization step is subjected to solid-liquid separation by means of a microfiltration membrane, an ultrafiltration membrane, or a filter, a reverse osmosis membrane separation step in which the water separated in the solid-liquid separation step is treated with a reverse osmosis membrane and the filtrate water is taken as treated water out of the system, and a crystallization step in which an alkali is added to the high-concentration water resulting from the reverse osmosis membrane separation step and the metals contained in the liquid are precipitated as carbonates by a crystallization method in which acid-insoluble particles are used as seed crystals.