Efficiency and Mechanism of Landfill Leachate Removal by nZVI Enhanced UV/PDS Process

WANG Wenchuan; TAN Gang; LIU Haisha; MU Liangyu

doi:10.19672/j.cnki.1003-6504.2623.22.338

Abstract：In order to explore the effect of nano zero-valent iron(nZVI)on the removal of organic matter from landfill leachate membrane bioreactor(MBR)by ultraviolet(UV)-activated persulfate(PDS)process,the removal rules of refrac-tory organic matter in MBR in different processes(UV,PDS,UV/PDS and nZVI/UV/PDS)were studied by analyz-ing the changes of conventional water quality index and spectral index.In addition,X-ray diffraction(XRD),scanning-elec-tron microscopy(SEM),element dispersive spectrometer(EDS),and X-ray photoemission spectroscopy(XPS)analyses re-vealed the phase changes of the nZVI before and after reaction and the activation mechanisms in the process.The re-sults showed that the UV/PDS process had a certain removal effect on refractory organic matter in the MBR effluent,and increasing the PDS dosage can improve the removal effect of organic matter in MBR effluent and reduce the humi-fication degree of the MBR effluent.Compared with UV/PDS process,the removal efficiency of nZVI/UV/PDS process for refractory organic matter in MBR effluent is greatly improved.Under conditions of nZVI dosage of 40 mmol/L,the UV power of 14 W,PDS dosage of 40 mmol/L,and reaction time of 10 min,the UV254 removal efficiency and rate con-stant of nZVI/UV/PDS process for MBR effluent were 51.52％and 0.072 4 min-1,respectively,which were 32.80％and 0.059 0 min-1 higher than that of UV/PDS process with the same reaction conditions.The mechanism of nZVI/UV/PDS process for the degradation of refractory organic matter of MBR effluent from landfill leachate MBR effluent can be at-tributed to homogeneous and heterogeneous Fenton-like reactions and the adsorption and precipitation of iron-based col-loids on organic matter.The results of this study can provide a theoretical reference for removing refractory organic mat-ter in MBR effluent.