Transformation mechanisms of refractory organic matter in mature landfill leachate treated using an Fe0-participated O3/H2O2 process

Abstract

An Fe0-participated O3/H2O2 (Fe0-O3/H2O2) process was applied to remove refractory organic matter (OM) in semi-aerobic aged refuse biofilter (SAARB) leachate arising from treating mature landfill leachate. The degradation and transformation characteristics of refractory OM were revealed at molecular level. Removal efficiencies of aromatic substances were 63.55% by the Fe0-O3/H2O2 process (much higher than in other single or binary processes), and fulvic- and humic-like substances were more effectively degraded by this process than by other treatments. According to Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS), 6645 categories of OM in SAARB leachate were identified. Although there was little difference in number of OM categories after treatment using the single-O3 and Fe0-O3/H2O2 processes, Fe0-O3/H2O2 process can better reduce OM relative abundance. It is noteworthy that the Fe0-O3/H2O2 process more effectively degraded CHONS compounds than the single-O3 process, while also producing more CHO compounds having higher bio-availability. The enhanced degradation efficiency of the Fe0-O3/H2O2 process were attributed to the formation of the Fenton process initiated by leached Fe2+ and H2O2. The heterogeneous catalytic effect from iron (hydro) oxides for O3/H2O2 also increased the treatment capacity of the Fe0-O3/H2O2 process, resulting in better total organic carbon removal. The Fe0-O3/H2O2 process is an efficient method for removing refractory OM in SAARB leachate.