Transformation characteristics of dissolved organic matter in landfill leachate nanofiltrated concentrate during ozonation-based advanced oxidation systems

Ozone alone or Ozone advanced oxidation technology can effectively remove dissolved organic matter (DOM) from landfill leachate concentrate, but the transformation characteristics of complex DOM in the oxidation process are not clear. This paper used Orbitrap MS to study the transformation characteristics of DOM in O3 and UV/O3 systems in landfill leachate nanofiltration concentrate flocculation effluent (NFFE) at the molecular level. The results showed that the O3 and UV/O3 systems could preferentially decompose aliphatic and low -oxygen highly unsaturated phenolic DOM with reduced and unsaturated characteristics, forming aliphatic and highoxygen highly unsaturated phenolic products with relatively higher oxidized degree and saturated degree. Compared to the O3 system, the UV/O3 system exhibited a stronger DOM transformation ability with reducing and saturation characteristics, likely forming more kinds of products. The dominant reactions of DOM in NFFE under the action of O3 and the UV/O3 systems were dealkylation and oxygenation. This study provided a theoretical basis for removing DOM in landfill leachate concentrate.