Research of pretreatment for reverse osmosis in landfill leachate treatment process

Landfill leachate treated by reverse osmosis poses significant environmental challenges due to high conductivity and Chemical Oxygen Demand (COD) in southwest China. This study investigates the efficacy of a coagulation + Fenton pretreatment in enhancing the performance of Reverse Osmosis (RO) systems for landfill leachate treatment. The study monitored the conductivity and osmosis pressure of landfill leachate pre-treated with coagulation and Fenton processes. Coagulation was optimized at pH 6.5 using polyferric sulfate (PFS) as the coagulant, followed by the addition of H₂O₂. Pretreatment reduced leachate conductivity from 18.62 mS/cm to 9.68 mS/cm and decreased the average osmosis pressure by 3.2 bar. The optimal COD removal rate of 64.03% was achieved with a PFS dosage of 1.2 g/L and H₂O₂ dosage of 8 mL/L. The findings suggest that the coagulation and Fenton pretreatment significantly enhances RO efficiency by lowering conductivity and osmosis pressure. The reduction in COD indicates improved organic pollutant removal, crucial for minimizing RO membrane fouling. The pretreatment method substantially improves RO performance in landfill leachate treatment, offering a viable approach for managing high-conductivity waste streams.