Study On Treatment Of Landfill Leachate By Coagulation-electro Fenton Method

Landfill leachate was a kind of wastewater which had high concentration of refractory organic matters, which had some characteristics such as high concentration and a great variety of pollutants, changeable water quality. Landfill leachate would cause serious damage for the ecological environment and human health if it was not treated to discharge into environment. Bad effects, incomplete pollutant remove and decolorize were existed in the application of conventional treatment for landfill leachate. On the basis of Fenton method, electro Fenton could automatically produce hydrogen peroxide and hydroxyl radical which had a strong oxidation property. Electro Fenton reaction improved the treatment effect of high concentration of organic matters compared with Fenton reaction. Moreover, lower cost made Electro Fenton method a broad application prospect.The combination technology of coagulation-electro Fenton was used in the treatment process of landfill leachate in this study, the coagulation experiment of landfill leachate was carried out in the fixed time speed change agitator, coagulation was used as a pretreatment to reduce loading of landfill leachate in the electro Fenton stage. In this paper author conducted the comparative study of polaluminum chloride (PAC), Polymeric Ferric Sulfate (PFS) and ferric trichloride (FeCl3) to treat landfill leachate, Results showed that PFS was the best coagulant for the removal of CODCr and turbidity of landfill leachat. Removal rate of CODCr and turbidity were respectively45%and48.3%under the condition of2200mg/L PFS and PH=7. Results of coagulation experiment showed that PFS was the best coagulant for the pretreatment of landfill leachate.Electro Fenton was applied to treat landfill leachate which was pretreated by coagulation, the factors such as Fe2+dose, initial PH, reaction time, voltage and board spacing were studied in the experiment. Result showed that the removal rate of CODCr was45%under the conditions of initial pH=3, temperature=30℃,CFc2+=3200mg/L, voltage=6V and distance between the electrodes=3cm, a first-order kinetic equation Y=0.002+0.01121X、Y=0.04794+0.00373AX and Y=0.90617+0.00539X fitted well.The response surface method (RSM) was used to optimize results of landfill leachate by electro Fenton process. Three factors Fe2+dosing quantity, voltage and reaction time were studied in the experiment design of Box-Behnken, the response surface model [Y=66.1+0.4625X1+0.6875X2+2.475X3-6.975X,X1+1.8X1X2-2.675X,X3-14.825X2X2+0.425X2X3-11.1X3X3] was determined by the analysis of response surface method.The analysis of response surface showed that the interaction between Fe2+dosing quantity and the reaction time had great influence on CODCr removal rate, followed by voltage and reaction time interaction. The optimal results: Fe2+dosing quantity, voltage, and reaction time were3219.2mg/1,6.11V and180min. The variance analysis of model showed that F value and R2were24.2and0.977, it explained that the quadratic equation is significant, Analysis of variance showed that the model can well simulate the treatment of landfill leachate by electro Fenton. Therefore, the combination technology of coagulation-electro Fenton was an efficient method to treat landfill leachate.