Treatment of Landfill Leachate by Microwave-Fenton Oxidation Process Catalyzed by Fe2+ Loaded on GAC

Abstract Landfill leachate is one kind of the most harmful types of high-concentration organic waste water. The effective processing method is necessary to improve the treating efficiency of landfill leachate. In this study, the microwave-Fenton oxidation process was conducted to treat aged landfill leachate with the catalytic effect of Fe2+ loaded on granular activated carbon (GAC). The removal ratios of chemical oxygen demand (COD) and NH3-N were adopted as the indexes to analyze the influence of several factors, like the amount of loading Fe2+, the GAC dosage, the microwave irradiation time, the microwave power, the H2O2 dosage, and the pH value of the water sample on the efficiency of the Fenton reagent oxidation to landfill leachate. The corresponding microanalysis and kinetics were also performed. The results indicate that microwave energy can enhance the Fenton oxidation reaction and promote colloidal flocculation in the leachate. The removal ratio of COD is mainly because of oxidation, whereas that of NH3-N is mainly because of the flocculation and adsorption. Under the optimal conditions, loading Fe2+ amount = 33.32 mg/g, GAC dosage = 10 g/l, microwave power = 720 W, microwave irradiation time = 30 min, H2O2 (concentration of 30 %) dosage = 0.10 mol/l, and initial pH value = 3, the maximum remova1 ratios of COD and NH3-N are, respectively, up to 93.01 % and 85.76 %. The characteristic peaks of the organic pollutants in treated landfill leachate disappear or significantly weaken, which means that the proposed process is effective. In addition, according to the experiment results, a kinetics model of microwave-Fenton oxidation reaction is established preliminarily.