Comprehensive analysis of the integrated electro-coagulation and membrane filtration process for semiconductor wastewater treatment

Abstract

Dissolved silica poses a significant challenge in semiconductor wastewater treatment due to its propensity to cause scaling and its resistance to removal, particularly due to its low molecular weight and its uncharged nature under neutral pH conditions. This study thus focuses on optimizing the integrated electro-coagulation (EC) and microfiltration (MF) membrane process, which involves the rapid coagulation of dissolved silica and the subsequent removal of the resulting coagulated EC flocs using a membrane. Various anode-cathode combinations were assessed in the EC process to determine the most effective electrode pairing for dissolved silica removal and system maintenance. Our findings revealed that an AlAl electrode combination facilitated efficient dissolved silica removal, reducing concentrations to levels that prevent scaling under charge loadings exceeding 450 C/L. Additionally, different types of polymeric or ceramic membranes were assessed downstream of the EC process to investigate further removal of coagulated dissolved silica flocs and to compare associated membrane fouling. Ceramic membranes exhibited superior fouling resistance, highlighting the role of EC flocs as a major contributor to membrane fouling. This study explores diverse operational conditions for the integrated EC and MF membrane process to achieve the effective removal of dissolved silica. Collectively, our findings provide valuable insights for the rapid removal of other hazardous contaminants commonly found in semiconductor wastewater, thus paving the way for more effective wastewater treatment processes.