Integrated electrocoagulation and membrane filtration for PAH removal from realistic industrial wastewater: effectiveness and mechanisms

Abstract

In this study, biologically treated, paper-making wastewater (PMWW) containing toxic polycyclic aromatic hydrocarbons (PAHs) was employed as the feedwater to investigate the effectiveness and mechanisms of integrated electrocoagulation (EC) and membrane filtration for the control of PAH pollution incurred by industrial wastewater discharge. The results showed that the integrated treatment was capable of removing more than 90% of polyaromatic hydrocarbon compounds (PAHs) and total organic carbon (TOC) from the wastewater. Specifically, the EC pretreatment contributed to approximately 40% TOC removal and 75% PAH removal via the combined effects of coagulation and oxidation, thereby significantly lowering the contaminant loading of the LPRO treatment. Among the PAHs removed by the EC, 3-ring and 4-ring compounds, including acenaphthene, anthracene, phenanthrene, fluorene and fluoranthene were effectively removed. However, EC-induced degradation of humic-like and fulvic-like substances produced 2-ring PAH compounds, including naphthalene and dimethylnaphthalene, that did not exist in the PMWW. Very importantly, the LPRO treatment efficiently rejected residual PAH compounds in the EC effluent, including those formed by EC treatment, through the solution-diffusion process. Overall, the quality of the final effluent meets the requirements for industrial water reuse; this exhibits the potential value of EC–LPRO for PAH pollution control.