Purification and reuse of heavy metals containing wastewaters from electroplating plants

Abstract

Purification of copper- and chrome-containing rinse wastewaters from electroplating plants (concentration of heavy metals — 20–100 mg/l) has been studied. The wastewaters have been treated with various trademark ion exchangers (products of firms Dow Chemical and Rohm & Haas Co., USA, Bayer, Germany).The specific ion exchangers for purification of the treated water have also been used. The initial and final concentrations of heavy metals were determined by means of atomic absorption spectrophotometer. It has been established that the breakthrough capacities of the tested ion exchangers are 0.5–1.8 eq/l. The concentration of copper and chrome in the purified water is below 0.05 mg/l and the water can be reused. The changes that occur in the polymeric structure and in the ionic groups have also been studied. The data obtained show that they change insignificantly. During the purification of wastewater heavy metals containing sludges are formed .They are products of the reagents neutralization of the effluents from the regeneration of ion exchangers. The insoluble metal hydroxides after filtration are solidified with the addition of cement and CaO. It was found that the solid products have good stability. The experimental results show that the experimented ion exchangers are effective for copper and chrome removal. This is one of possibilities for solving the problem with heavy metals in wastewater from electroplating plants.