Split Dosing Of H2o2 For Enhancing Recalcitrant Organics Removal From Landfill Leachate In The Fe-0/H2o2 Process: Degradation Efficiency And Mechanism

This study applied a simple but efficient hydrogen peroxide (H2O2) split-dosing strategy as part of a zero valent iron (Fe0)/H2O2 process to effectively remove refractory organics from landfill leachate. Results showed that both the traditional Fenton and Fe0/H2O2 processes produced comparable treatment results, but the Fe0/H2O2 process (advantageously) produced much less sludge. Furthermore, Fe0/H2O2 process using a split H2O2 dosing strategy removed refractory organics from landfill leachate better than using the same oxidant dosage in a single dose. Under optimized operating conditions (H2O2 dosage = 12 mL/L) that included four small sub-doses of H2O2, removal efficiencies of total organic carbon, light absorbance at 254 nm, and color number were 56.76%, 58.59% and 94.56%, respectively. In addition, humic-like substances as refractory organics in the leachate were almost completely removed by the improved Fe0/H2O2 process. Our results demonstrated that the split-dosing strategy substantially enhanced hydroxyl radical (center dot OH) production in the Fe0/H2O2 process. Overall, the catalytic mechanism of the unique Fe0/H2O2 process can be assigned to the homogeneous catalytic effect of Fe2+ from Fe0 leaching and the heterogenous catalytic effect of iron (hydro) oxides, both of which act on H2O2 to produce center dot OH. This study provides an efficient strategy that can enhance refractory organics removal efficiency for practical application of the Fe0/H2O2 process.