Study On Degradation Of Landfill Leachate Organics By Catalytic Heterogeneous Fenton Process Coupled With Microwave Radiation

According to the characteristics of complex water quality, high concentrationpollutants and low biodegradability of landfill leachate especially leachate in the later stage,and the problems of conventional Fenton system which is the requirement of environmentof specific acidity, high iron concentration in the water, catalyst separation, recovery andrecycling, in this paper, aiming at the leachates that come from ChongqingChangshengqiao sanitary landfill, the treatment for degradation of later landfill leachateorganics by catalytic heterogeneous Fenton process had been studied. The two catalystsAC-Cu, AC-Fe For the carrier of activated carbon prepared by dipping-roasting, andstudied the catalyst characterization and repeat regeneration properties; the effects werestudied; degradation and reaction mechanism of catalytic heterogeneous Fenton oxidationpollutants coupled with microwave radiation were analysised and investigated. Thekinetics process of microwave/H₂O₂/catalyst system to pollutants degradation was studiedand the comparison analysis of the two catalytic heterogeneous Fenton oxidation systemscoupled with microwave radiation were carried out by kinetic theory and experimentaldata.The results showed that specific surface area, pore size distribution and surfacefunctional groups of activated carbon had been adjusted by modification, which had aneffect on loading process of metal, finally influence the catalytic oxidative activity ofcatalysts to pollutants. On the surface of good effect catalyst AC-Cu, the main forms ofcopper was CuO and followed by Cu, accounts for the quality score respectively was94.78%and5.22%; On the surface of good effect catalyst AC-Fe, the forms of iron wereFe, FeO and Fe₂O₃, accounts for the quality score respectively was38.97%,37.57%and23.46%.When copper, iron content of catalyst AC-Cu, AC-Fe was2.53wt%,1.12wt%respectively, the COD removal were highest. Suitable calcination condition was for2hoursand300℃. In addition, after catalyst repeated used five times, the COD removal of landfillleachate was respectively lower5.6%,5.84%than the first time use, which means catalyticactivity and stability of catalysts changed a little.For AC-Cu, AC-Fe system, COD removal of landfill leachate achieved better effectand COD removal rate was respectively84.13%and60.16%under the conditions of initialPH3, the added H₂O₂4.98×10³mg·L^-1,0.33×10³mg·L^-1, the catalyst0.5×10⁴mg·L-1,2.0×10⁴mg·L^-1, microwave radiation of10minutes at420w power level. The function C=a+b exp-k twas fitted for the change of the COD of landfill leachate with timeon different treatment conditions, all of the R2were greater than0.90, fitting function wasbetter described the actual change process.The results of COD removal of landfill leachate by microwave/H₂O₂/AC-Cu systemand microwave/H₂O₂/AC-Cu system showed that, for Cu and Fe, the two transition metalswith3d rail, which as the activity group points of the catalysts, the system structure, theaction mechanism and the results were similar. The differences of the COD removal oflandfill leachate maybe concerned with the difference of catalyst metal activities, solutionenvironmental impact and H₂O₂quenching active free radicals in different system.