Deng, YN; Chen, WM; Luo, ZY; Cui, YQ; Li, QB
A large number of refractory organics residual in semi-aerobic aged refuse biofilter (SAARB) leachate, ozone/manganese-dioxide (O 3 /MnO 2 ) process was used to catalytically decompose organics from SAARB treated landfill leachate. Effects of ozone dosage, MnO 2 dosage and initial pH on the removal of organic substances and reaction kinetics were investigated. UV-Vis and 3D-EEM tests were applied to investigate the transformation mechanism of recalcitrant organics in O 3 /MnO 2 process. In addition, the phase change of MnO 2 before and after reaction and its catalytic mechanism were investigated by SEM, EDS, XRD and XPS. Results showed that when the ozone dosage of 18.92mg/min, initial pH of 3 and reaction time of 20min, compared to the ozone alone treatment, the O 3 /MnO 2 peroxide treatment was significantly improved with 2mg/L MnO 2 addition. The removal efficiencies of COD, UV 254 , and CN by 24.66%, 4.95%, and 12.57%, respectively, and the chromophore was most easily attacked by ozone. UV-Vis spectra and 3D-EEM spectrum were both illustrated that O 3 /MnO 2 process can significantly decrease the aromaticity degree, molecular weight and condensation degree of organic substances in wastewater, which degradation efficiency of benzene ring compounds was improved significantly and also greatly proved biodegradability of leachate effluent. Meanwhile, After O 3 /MnO 2 process, MnO 2 has not shown the change of the peak value of the new valence state, and Mn(Ⅳ) played a dominate role in the catalytic process. In order to promote the selectivity of hydroxyl radical and the catalytic performance, indicating that the mechanism of O 3 /MnO 2 process was MnO 2 catalyzed O 3 to generate hydroxyl radicals and transformed into hydrated manganese dioxide, which changed the physicochemical properties of the catalyst surface. © 2018, Editorial Board of China Environmental Science. All right reserved.