The Experimental Study Of Using Modified Fly Ash In Advanced Treatment Of Landfill Leachate

In the last decade, as the explosive growth of urbanization in our country, consumer waste has been grown constantly, thereby, a large number of landfill leachate is produced. Thus, search for the efficient methods in order to treat the landfill leachate have been demand prompt solution. Fly ash is a waste from coal-burning power plants and some other burners. As the demands of sources of energy have been increasing with each passing day, the productions of fly ash have been stepped up. How to achieve to the comprehensive utilization of fly ash has become an important research topic in environmental field.In this study, modified fly ash was used for landfill leachate advanced treatment. First, the raw fly ash was modified by different modifiers. The degradation rate of CODCr and the decolorization of landfill leachate were used as the target index. Through comparison, the best modified fly ash was treated by calcium carbonate which mixed calcium carbonate with raw fly ash at mass ratio of 1:9, then roasted at 800℃for two hours. Compared to raw fly ash, the surface area and the pore volume of modified fly ash had been increased by treated through SEM. Used XRD to analyze and determine the major crystal phases in raw and modified fly ash.After the experimental modified fly ash was prepared, the optimum experimental results of using modified fly ash for landfill leachate advanced treatment were determined through single factor experiments and orthogonal experiment. Which were the inventory rating of modified fly ash:0.24g/mL; the vibration time:60min; the initial pH=10. The result showed that it's possible to remove 82.8% and 86.5% of CODCr and colourity respectively. The CODCr of the effluent was 68.7mg/L which accorded to the CODCr＜100mg/L in pollutant discharge standard of sanitary fill (GB 16889-2008). The adsorption equilibrium and kinetic model for the removal of CODCr from landfill leachate by modified fly ash were studied in the text. The results showed that removed CODCr from landfill leachate fitted in Freundlich isotherm model, the adsorption process of CODCr from landfill leachate conformed to the pseudo second-order kinetic model.According to the chamber test, dynamic test was made. Through dynamic test, the adsorptivity of modified fly ash was much better than raw fly ash when adsorbed CODCr and colourity in landfill leachate, the CODCr could reduce to 64.6mg/L. The adsorption capacity of modified fly ash was 5.98mg/g in the study. The adsorbent which has been used can be regenerated, and the regenerated fly ash also had good adsorptivity in adsorbing CODCr and colourity from landfill leachate. The adsorption rate of CODCr and colourity came to 81.7% and 98.5% respectively. In the study, analyzed the economic accounting of using modified fly ash for landfill leachate treatment, which was 12.1 Yuan/t.At last, GC-MS was used to analyze the organic component of initial landfill leachate and effluent, in order to evaluate the adsoptivity of modified fly ash in the other side.