Pretreatment of landfill leachate by chemical oxidation processes

摘要

Kinetics and efficiency of Fenton's and ozonation processes for the pretreatment of two landfillleachates (fresh and mature) resulting from municipal waste disposal were studied. Both samplespresented high organic load, high toxicity and low biodegradability. These were the reasons whyoxidative treatment was proposed. Fresh and mature leachate showed different behaviors in theoxidation experiments. The final extents of removal were attained in comparable time intervalsin both oxidation systems. Maximal removal of organics by the Fenton's oxidation reached morethan 50 % according to COD. Zero or first order kinetics were found the best to describe theorganic components (in terms of COD and DOC) removal by the Fenton's oxidation for bothlandfill leachates. Higher reaction rate values of the Fenton's oxidation were achieved with freshleachate samples. The efficiency of initial organics removal with ozone was about 70 % for matureleachate, while in case of the fresh one only 41 % of COD were removed. The best fits of COD andDOC experimental data from oxidation of fresh and mature leachates were obtained by a combinedkinetic model. No significant improvement of the biodegradability of landfill leachates was achievedusing these treatment procedures. Regarding toxicity, ozonation showed to be more effective thanthe Fenton's oxidation. Advanced oxidation experiments confirmed that the Fenton's oxidation andozonation are comparable oxidative treatment techniques for the reduction of organic pollution inthe investigated municipal landfill leachates. However, neither of them is effective enough to be usedas a pretreatment method followed by biological treatment.