Treatment of landfill leachate in the MBR and catalytic ozonation coupled system based on Mn[sbnd]Ni catalyst: Efficiency and bio/chemical mechanism

Complex organic matters and high concentrations of ammonia nitrogen in landfill leachate required deep treatment before discharge. In this study, a catalytic ozonation-membrane bioreactor (MBR) process equipped with Mn[sbnd]Ni composite loaded carbon felt catalysts (Mn-Ni@CF) was proposed for landfill leachate treatment. The mechanism of catalytic ozonation was analyzed in focus. The abundant valence of manganese and nickel loaded on Mn-Ni@CF could promote the electron transfer and form the Mn⁴⁺ - O₂ - Ni²⁺ redox couples. The redox reactions occurred in bimetallic enhanced transformation of active sites and generation of [rad]OH and [rad]O₂⁻. It was found that the removal of humic acid substances by Mn-Ni@CF catalysts achieved 85.5 % after 2 h of catalytic ozonation reaction. Coupling with MBR, the removal efficiencies of chemical oxygen demand (COD) and NH₄⁺-N for 25 L of landfill leachate were 99.8 % and 91.4 % after 13 days of operation, respectively. Proteobacteria and Actinobacteriota were effective to promote the nitrification-denitrification reaction. Thauera and Truepera could degrade organic matter. This study provided a new strategy for the efficient treatment of landfill leachate.