Abstract:

In this investigation,with the granular activated carbon ( GAC) loaded with Fe²⁺ as the catalyst,the microwave-enhanced Fenton reagent oxidation process was adopted to treat aged landfill leachate. Then,the COD and NH₃-N removals were taken as the indexes to analyze the influence of the Fe²⁺ loading amount,the GAC dosage,the microwave treatment time,the microwave power,the H₂O₂ dosage and the treatment solution’s pH value on the Fenton reagent oxidation. The corresponding microanalysis and kinetics were also carried out. The results indicate that ( 1) microwave can enhance the Fenton oxidation and promote the colloidal flocculation in the leachate;( 2) the COD removal is mainly due to the oxidation,while the NH₃-N removal is mainly due to the flocculation and adsorption; ( 3) the maximum COD and NH₃-N removals are respectively up to 93.01% and 85.76% in optimal conditions,namely,an Fe²⁺ loading amount of 33.32mg /g,a GAC dosage of 10 g /L,a microwave power of 720W,a microwave treatment time of 30min,a concentration of 30%H₂O₂ of 0.10mol /L and an initial pH value of 3; and ( 4) the characteristic peaks of the organic pollutants in the treated landfill leachate disappear or significantly weaken,which means that the proposed process is preferable. In addition,a kinetics model of microwaveenhanced Fenton reagent oxidation reaction is preliminarily established according to the experimental results.

Key words: landfill leachate, microwave, granular activated carbon, oxidation, kinetics