Navigating challenges in electroplating wastewater management: A study on pollutant removal characteristics and economic impacts by physicochemical treatment

Abstract

The electroplating industry contributes significantly to environmental pollution, particularly through its discharge of complex wastewater containing heavy metals, organic pollutants, and refractory substances. To address the challenge of managing these pollutants, the treatment processes of a full-scale electroplating wastewater treatment plant in Shenzhen, China, were investigated in this study. The physicochemical treatment units were examined regarding the removal efficiency of target pollutants, sludge production, and cost implications. Substantial variability in treatment performance was observed due to fluctuations in wastewater quality and quantity. The chemical oxidation demand (COD) removal by the physicochemical treatment ranged from 24.26 % to 78.6 %, with effluent concentrations between 400–1000 mg/L, affected by refractory substances and improper dosing. Heavy metal removal was more effective at higher influent concentrations, with chromium achieving up to 99.83 % removal, while nickel and copper showed inconsistent performance due to complexed forms and dosing issues. Nitrogen removal reduced the total nitrogen concentration from 75.43–351.09 mg/L to ∼25–100 mg/L, relying on oxidation (NaClO) and sedimentation, but left residual nitrogen for biochemical treatment. Phosphorus removal, primarily through chemical precipitation, reduced total phosphorous to < 10 mg/L in optimal cases but fluctuated significantly due to poor pH control and competing reactions. Overall, while primary sedimentation and chemical processes contributed significantly, challenges such as process instability, refractory pollutants, and improper dosing impacted treatment consistency. These findings underscore the importance of optimizing treatment parameters and adopting innovative strategies to enhance process stability and cost-effectiveness. By advancing the understanding of electroplating wastewater treatment challenges, this study provides critical insights for improving industrial wastewater management and promoting sustainable environmental practices.