도금폐수 내 중금속 침전 제거 및 슬러지 감량에 관한 연구

Abstract

Background: Electroplating processes generate wastewater containing high concentrations of heavy metals such as copper, zinc, nickel, and hexavalent chromium. These metals are non-biodegradable and tend to accumulate in organisms, posing serious environmental and health risks. Conventional treatments like hydroxide precipitation are widely used, but they often result in excessive sludge generation and limited removal efficiency under varying conditions. Objectives: This study aims to evaluate the feasibility of using sulfur-rich iron sulfide (FeS4) as an effective and environmentally friendly precipitating agent for removing heavy metals from electroplating wastewater. It also investigates the potential of FeS4 to reduce sludge production compared to the conventional hydroxide method, while also preventing the formation of hydrogen sulfide (H2S) gas. Methods: Laboratory-scale batch experiments were conducted using synthetic electroplating wastewater containing Cu2+, Zn2+, Ni2+, and Cr6+. The effects of pH (5.0~9.0) and FeS4 dosage (0.5~2.0 g/L) on removal efficiency and sludge generation were examined. Metal concentrations were analyzed using ICP-OES, and sludge volume was measured after drying. Results: The optimal condition was observed at a pH of 8.0 and with 1.5 g/L of FeS4, achieving removal efficiencies of 96.3% for Cu2+, 93.8% for Zn2+, 91.5% for Ni2+, and 87.9% for Cr6+. Compared to the hydroxide precipitation method, sludge volume was reduced by approximately 40%, and no hydrogen sulfide gas was detected during the process. Conclusions: The FeS4-based precipitation process shows strong potential for industrial application in electroplating wastewater treatment. It provides high removal efficiency, reduced sludge generation, and safer operation without H2S gas emission, making it a viable and sustainable alternative to conventional treatment methods.