Removal characteristics of organic matter during pretreatment for membrane-based food processing wastewater reclamation

Abstract

In this study, we investigated coagulants such as polyaluminum chloride (PACl) and ferric chloride (FeCl3) and the combination of a coagulant and powdered activated carbon (PAC) for the removal of dissolved organic matter (DOM) from fish processing effluent to reduce membrane fouling in microfiltration. The efficiency of each pretreatment was investigated through analyses of dissolved organic carbon (DOC) and ultraviolet absorbance at 254 nm (UVA(254)). Membrane flux and silt density index (SDI) analyses were performed to evaluate membrane fouling; molecular weight distributions (MWD) and fluorescence excitation-emission matrix (FEEM) spectroscopy were analyzed to assess DOM characteristics. The results demonstrated that FeCl3 exhibited higher DOC and UVA(254) removals than PACl for food processing effluent and a combination of FeCl3 and PAC provided comparatively better results than simple FeCl3 coagulation for the removal of DOM from fish processing effluent. This study suggests that membrane fouling could be minimized by proper pretreatment of food processing effluent using a combination of coagulation (FeCl3) and adsorption (PAC). Analyses of MWD and FEEM revealed that the combination of FeCl3 and PAC was more efficient at removing hydrophobic and small-sized DOM.