Experimental study on advanced treatment of landfill leachate by ultraviolet catalytic persulfate

Abstract

Landfill leachate is characterized by complex composition and difficult degradation. In this paper, we compared the effects of advanced treatment of ultraviolet (UV) system, persulfate (PS) system and ultraviolet/persulfate (UV/PS) system on landfill leachate. The results showed that the UV/PS system had the best removal efficiency. When the initial concentration of humic acid was 200 mg/L, the dosing of PS was 25 mmol/L, and the initial pH was 4, the maximum removal rates of UV 254 and TOC were 89.62% and 76.17%. Namely, the value of SUVA 254 decreased to 7.6603 L/(m ⋅ mg). It follows that the UV/PS system is effective in the removal of humic acid in the landfill leachate. In addition, this paper investigated the effects of temperature, initial pH and dosing ratio of chemicals on the treatment of leachate by UV/PS system. It was found that the optimal process conditions were 35 °C, pH = 4, dosing ratio = 2, and 24 h of operation. Under these conditions, the maximum removal rates of COD and TOC were 82.64% and 66.69%. The removal capacity of the system was in accordance with the pseudo-second-order kinetic equation. Therefore, this paper can provide a reference for the advanced treatment of landfill leachate. • An advanced oxidation technology for the removal of landfill leachate after biochemical treatment was presented. • Humic acid was used as a model for organic matter. The value of SUVA 254 decreased to 7.660315 L/ (m ⋅ mg) under the optimum conditions. • Under the optimal conditions, the removal rates of COD and TOC of landfill leachate after biochemical treatment reached 82.64% and 66.69%. • SR-AOPs are more efficient, economical and widely applicable compared to other technologies for deep treatment of landfill leachate.