Fouling potential and reclamation feasibility for a closed landfill leachate treated by various pretreatment processes on membrane system

Abstract

AbstractA closed sanitary landfill leachate with high recalcitrant organics (COD = 4,000 mg/L) in a full-scale plant was intended for reuse. Various methods including coagulation, enhanced coagulation, microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO) were conducted, and modified fouling index (MFI) was used to evaluate the membrane fouling potential. The results showed that the current biological treatment process (activated sludge and sedimentation) in the full-scale plant only achieved 20% of COD removal with MFI still higher than 550,000 s/L2. After conventional coagulation (CC) process, the MFI reduced only to 22,497 s/L2, and additional MF/UF processes can only lower the MFI value to 28.5 s/L2, which is still higher than the recommended operational value of 10 s/L2 for NF or 2 s/L2 for RO. Consequently, enhanced coagulation was used to replace the current coagulation process before MF/UF processes, and the result shows the MFI value was capably lowered to 10.9...