Study On The Advanced Treatment Of Incineration Leachate By Ozone-persulfate Process And MnO₂-Co₃O₄/AC Catalytic Ozonation

Fresh leachate from municipal solid waste incineration plant was previous treated by the combined’ anaerobic-aerobic-anoxic’ bio-treatment process. The effluents from this process need further treatment prior to release, as it still contains refractory organic component with poor biodegradability (BOD5/COD ratio, B/C:0.13～0.15). In this study, two advanced oxidation process, ozone-persulfate process and MnO2-Co3O4/AC catalytic ozonation were applied for further processing this leachate effluent to increase its B/C, so that to create favorable conditions for the further treatment of the subsequent biological process and reduce the cost of treatment.Effects of various ozone dosage and persulfate dosage on oxidation by ozone-persulfate process were investigated. The experimental results showed that the B/C of leachate effluent could increased from 0.13 to 0.49 within 20 min under the condition of 14.9 mg/(min·L) and 0.4 g/L dosages of ozone and persulfate, respectively. This further illustrated that the ozone-persulfate process is feasible for the advanced treatment of leachate effluents. To further document the degradation and transformation of the leachate effluent during ozone-persulfate process, UV-Vis spectra, excitation and emission matrix (EEM) fluorescence spectra, Fourier transform infrared spectrometer (FT-IR) and gas chromatography mass spectrometry (GC-MS) were used to characterize the raw and treated leachate effluent. It can be concluded that ring-opening and chain scission reactions occurred during the oxidation process and C=O and C-O structures were formed from the breaking of C=C. These might be responsible for the generation of long chain alkane and the decrease of aromaticity. Both SO4-·and·OH radicals were excited and captured in this oxidation system and ozone oxidation played a major role involved in this oxidation treatment process.MnO2-Co3O4 composites were loaded on activated carbon (AC) by impregnation-precipitation and were characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The result showed the active component of catalyst were spinel Co3O4 and amorphous MnO2. The factors affecting catalytic performance included catalyst dosage, ozone dosage and initial pH were optimized. A significant improvement in B/C was observed in catalytic ozonation (from 0.15 to 0.80) while the optimal conditions of catalyst dosage, ozone dosage and initial pH were 0.4 g/L,14.9 mg/(min-L) and 9.0, respectively. UV-Vis spectra, EEM fluorescence spectra and high performance liquid chromatography (HPLC) were used to characterize the raw and treated leachate effluent to investigate the degradation of the leachate effluent. It can be concluded that MnO2-Co3O4/AC could effectively promote the generation of-OH, which contribute to a result that the humic-like and fulvic-like were almost completely degraded. Furthermore, the O3-(MnO2+Co3O4)/AC process played a good performance on degraded different molecular weight organics.