Experimental Research Of Treatment Of Landfill Leachate By A New UV-Fenton Reactor

With an increasing hazard of pollution of landfill leachate to the environment, economic and effective treatments of landfill leachate have become a hot research both at home and abroad. In recent years, due to its high efficiency of degradation and low economic cost in the homogeneous and heterogeneous phase, UV-Fenton technique has been utilized in advanced treatment of landfill leachate. According to the type of catalyzer and characteristic of landfill leachte, the original UV-Fenton reactor was improved and effects and influences of process parameters of the improved reactor on landfill leachate treatment were discussed. As a result, the applicabilty of the machine for landfill leachate was improved. Several conclusions were drawn by studies:(1)There are several main factors of treatment of landfill leachate in the homogeneous phase:initial pH, reaction time, H2O2 dosage, n(H2O2)/n(Fe2+), wavelength of UV lamp, power of UV lamp, aeration and addition modes of reagents. The results showed that considering economic factor, when initial pH was 3.5, reaction time was 90 mintutes, dosage of H2O2 was 60mmol/L, n(H2O2)/n(Fe2+) was 4, the power of UV lamp was 6W, the wavelength was 254nm,aeration was 2L/min, addition mode of reagents was dosing time of H2O2 was fourth and dosing time of FeSO4· 7H2O was once, the temperature was 20℃,the treatment of landfill leachate was optimal. At this time, the removal of COD was 71.88% and the removal of UV254 was 89.27%. The index BOD5/COD improved from 0.07 to 0.30, which means that the biodegradability of leachate was improved from not suitable biochemical status to suitable biochemical status. Through an intuitive analysis and UV-visible map analysis, homogeneous UV Fenton process effectively removes the chroma, ammonia nitrogen and organic substance with π-π transition and many phenyl rings of conjugated system.(2)A new type of catalyzed carrier-iron oxide coated sand was made using in the heterogeneous UV-Fenton experiment. The results showed that considering economic factor, when initial pH was 3.5, reaction time was 120 mintutes, dosage of H2O2 was 60mmol/L, the concentration of Fe2+ was 13.33 mmol/L, the power of UV lamp was 6W, the wavelength was 254nm, aeration was 2L/min, addition mode of reagents was dosing time of H2O2 was fourth, the temperature was 20℃, the catalyst dosage is 18g/L, the particle size is 0.425-0.600mm, the removal of COD was 68.75% and the removal of UV254 was 87.73%. The index BOD5/COD reached at 0.2725. Although the effect of heterogeneous UV-Fenton treatment can not emulate that of homogeneous Fenton reaction, the heterogeneous UV-Fenton reaction produced less iron sludge, and the catalyst could be recycled, so that it has a wide horizon of development in the industry.