Pretreatment Of Landfill Leachate In Near-neutral P H Condition By Persulfate Activated Fe-C Micro-electrolysis System

In recent years,iron-carbon microelectrolysis and Fenton method,one kind of landfill leachate treatment,has become a hot research topic.However,there are many problems in the practical application of Fenton treatment of landfill leachate,such as harsh reaction conditions?acidic?,difficulty of stabilizing saved drug?H₂O₂?,and larger sludge production.This study explores a new method for treating landfill leachate,persulfate combined with iron-carbon microelectrolysis?PS-ICME?system.This research mainly includes the following experimental work:?1?Single factor experiment:This chapter studied the effect of sodium persulfate?Na₂S₂O₈?concentration and Fe-C mass ratio on COD removal efficiency of leachate landfill pretreated by persulfate activated iron-carbon electrolysis.It has been indicated that the concentration of sodium persulfate added to 40 mM was the best economic experimental condition.When the dosage of sodium persulfate reached 80 mM,the COD removal rate reached the highest of 58.44%.When the Fe-C mass ratio was 3:1,the PS-ICME process had the highest efficiency?60.54%?for COD removal from landfill leachate.It also provided a data foundation for subsequent response surface analysis.?2?Static batch optimization experiment:BBD?Box-Behnken Design?response surface analysis was used to optimize the experimental conditions of pretreatment of landfill leachate by persulfate activated iron-carbon electrolysis.The variance analysis and significance test of the multivariate quadratic regression equation can be obtained from the3D response surface map:when pH=7,Fe-C mass ratio 3:1,sodium persulfate concentration85 mM,COD removal rate reached a maximum of 61.01%.It was proposed that the persulfate combined with iron-carbon microelectrolysis had better degradation effect of organic matter under neutral conditions.?3?Columnar dynamic continuous experiment:The columnar continuous penetration curve of PS-ICME under different gas conditions was obtained in the experiment.It showed that oxygen would promote the degradation of organic substances in the PS-ICME system,and verify that the PS-ICME combined process has certain feasibility in the actual industrial wastewater treatment.?4?Effect of initial pH on COD removal rate:The experimental results have showed that PS-ICME system followed the first-order kinetic model for COD degradation of landfill leachate.It was also suggested that the mechanism of PS-ICME process may include micro-electrolysis,strong oxidizing of persulfate,flocculation and precipitation of iron ions.?5?Three-dimensional fluorescence spectroscopy?3D-EEMs?:The three-dimensional fluorescence spectra of the raw and treated landfill leachate were measured.From the perspective of DOM,the analysis showed that the pretreatment of landfill leachate by PS-ICME process could also reduce the stability of landfill leachate and improve the degradation of organic matter.?6?Electron Spin Resonance Analysis?ESR?:The concentration of iron ions in the sample after the treatment was measured,and the spectrum of free radical intensity generated by PS-ICME under different pH conditions was analyzed.The mechanism of organic matter in landfill leachate pretreated by PS-ICME process was proposed.It was concluded that the persulfate combined with iron-carbon microelectrolysis has better degradation effect of organic matter under neutral conditions.