Enhanced Biodegradability Of Landfill Leachate Using Iron-carbon Microelectrolysis With Fenton Process

Leachate from sanitary landfill is a high concentration organic effluent whose composition is complicated and its quality and quantity is fluctuant wildly. If the garbage leachate is not treated properly,it will seriously contaminate the soil, groundwater and surface water, air, causing a secondary pollution. Therefore, landfill leachate treatment is still a worldwide problem.The mature leachate shows the lowest biodegradability properties with biological oxygen demand/chemical oxygen demand(BOD 5/COD) ratio below 0.1. The biological treatment process has been unable to effectively degradade the mature leachate. Therefore, the physicochemical processes, as a pretreatment step to biological processes are usually used to improve mature leachate biodegradability. Landfill leachate samples used in this study were taken from the Hei Mi-feng sanitary landfill located in Changsha, south of China. The landfill leachate was treated by iron-carbon microelectrolysis with Fenton process to enhance its biodegradability. The optimum process conditions of the method were achieved using single factor experiment and response surface methodology.The factors, such as initial p H, iron-carbon concentration, the mass ratio of iron to carbon, dosage of H2O2 and reaction time were investigated. Under the optimal conditions of initial p H of 3, iron-carbon concentration of 52g/L, iron to carbon mass ratio of 3, H2O2 dosage of 12ml/L, the removal efficiency of COD reached to 75% after reaction time of 1h. The ratio of BOD 5 to COD also increased from 0.075 to 0.25, which suggested that iron-carbon microelectrolysis with Fenton process could significantly improve the biodegradability of landfill leachate. Compared with the single iron-carbon microelectrolysis and Fenton process, the iron-carbon microelectrolysis with Fenton process showed better processing performance.According to the result of single factor ex periment, initial p H, iron-carbon concentration, iron to carbon mass ratio are three factors which have great effect on the pretreatment of landfill leachate. Response Surface Methodology(RSM) and quadratic polynomial regression model were used to optimiz e the operating parameters. According to the 3D and contour figure, the interaction between any two factors was notable. The optimal independent variables of iron-carbon microelectrolysis with Fenton process were suggested as following: initial p H of 3, iron-carbon concentration of 52g/L, iron to carbon mass ratio of 3, H 2O2 dosage of 12ml/L, reaction time of 1h, The experimental values for ratio of BOD5 to COD(0.25) was in good agreement with the values predicted from the models( 0.254), with relatively small errors between the predicted and the actual values.