| To improve the effluent quality and reduce pollutant concentration in landfill leachate, the processes of photocatalytic oxidation, TiO2/O3/UV, O3/UV and O3 were used to treat the effluent treated by biological processes. The effects of initial COD concentration, dose of photocatalyst, concentration of ozone and reaction time were evaluated.In the photocatalytic experiment, ZnO was chosen as the photocatalyst, response surface methodology was used to design the experiment and interpret the result. The COD removal was up to 39% under the conditions that photocatalyst was 9g/L, and reaction time was 75min, as well as initial COD concentration of landfill leachate was 440mg/L. The UV254 removal was up to 42.4% under the conditions that photocatalyst was 9.37g/L, and reaction time was 120min, as well as initial COD concentration was 771mg/L. The COD removal could be increased to 20%30% and UV254 removal could be increased to 40%60% with photacatalysis and ozone.During TiO2/O3/UV process, the result indicated that the process was effective under the conditions that the dose of TiO2 0.5g/L, the reaction time 2.0h, the concentration of ozone 16.8mg/L, the initial COD concentration less than 430mg/L, and pH neutral. In additon, the process could improve the biodegradability of landfill leachate obviously.Comparing the processes of TiO2/O3/UV, O3/UV and O3, it was found that TiO2/O3/UV was more effective than others in degrading organic matters under the conditions that the initial COD concentration of landfill leachate was 433mg/L and the concentration of ozone was 16.8mg/L. The result also indicated that the reaction time was different (TiO2/O3/UV3/UV3) when the three processes achieve the same treatment effect. The reaction time of TiO2/O3/UV was less 2030min than by O3/UV, and less 3090min than by O3. Because the cost of ozone is more expensive, saving time means saving cost. TiO2/O3/UV is better than others in advanced treatment of landfill leachate. |
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