This invention provides a method for treating waste water containing organic bases such as tetramethyl ammonium hydroxide and dissolved metals such as Mo W Cu and Ni which are generated from mask cleaning and Mo etching processes. The organic base along with Cu and Ni is first removed preferably by passing the effluent through a cation exchange resin followed by passing the cation exchanged effluent through an anion exchange resin to remove the Mo and W metals. The treated waste water meets federal guidelines for dissolved metal contaminant limits for water discharge to water ways. Alternatively filtered effluent is directly passed through an anion exchange resin to remove Mo and W and the dissolved TMAH and copper and nickel are removed by cation exchange.
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