Study On Photocatalytic Oxidation Of Leachate By Titanium Dioxide Under Simulated Sunlight

The treatment of landfill leachate has always been a difficult problem.At present,the commonly used biological method can not further degrade the biodegradable orgainc in the actual operation process,and the high-efficiency and low-energy titanium dioxide photocatalytic technology has a good effect on the treatment of the biodegradable organic matter in the leachate.In this stduy,nano-TiO₂,Sm-TiO₂ and Sm-N-TiO₂ were prepared by hydrothermal method.The degradation rate of methyl orange under sunlight was simulated and compared,and the catalyst with optimal photocatalytic activity was screened.Taking the actual leachate as the degradation target,the influence of external factors on the photocatalytic oxidation treatment of leachate was discussed,and a new idea of photocatalytic combined aged-waste-based reactor to treat leachate and accelerate the degradation of domestic waste was proposed.?1?The photocatalytic oxidation properties of the prepared materials for methyl orange were studied under simulated sunlight.When the hydrothermal reaction temperature was150°C,the initial Ti?SO₄?₂ concentration was 0.75 mol/L,and the titanium-urea ratio was 1:1,the degradation rate of methyl orange by nano-TiO₂ was the highest,which was 95.97%.The photocatalytic oxidation performance of Sm-TiO₂ and Sm-N-TiO₂ for methyl orange were lower than that of nano-TiO₂.Therefore,nano-TiO₂ was used in the subsequent experimental study.?2?The effect of external conditions on the photoreaction degradation of leachate was investigated.When nano-TiO₂ degraded leachate under the simulated sunlight,the chromaticity gradually decreased with the extension of illumination time,the fading rate reached 74.19%,and the COD twists and turns decreased;The increase of dosage increased the adsorption performance of the catalyst,200 mg was the optimum dosage of photocatalytic reaction,and the maximum COD removal rate and fading rate were 95.56%and 70%,respectively;The pH of leachate had a great influence on the removal of chroma,but it had no effect on the removal of COD.?3?Based on the research of the new denitrification bioreactor in the early stage of the subject group,the aged-waste-based reactor and photocatalytic reaction respectively utilize the biological and chemical processes to degrade the leachate,forming a photocatalytic oxidation and aged-waste-based bioreaction combined technology to treat leachate,and the purpose of accelerating the stabilization of domestic waste in anaerobic landfill can also be achived.During the acclimation stage,the two groups of reactors were stable.The results of the test phase showed that the combined device enhanced the biodegradability of the leachate,provided carbon source for microorganisms,had a good removal effect on ammonia nitrogen,nitrate nitrogen and COD.The photoreaction temperature had an effect on the nitrite nitrogen concentration.Recharging to an anaerobic landfill device could continue to accelerate the degradation of domestic waste,but further testing should be needed.?4?Photocatalyst characterization analysis showed that the prepared materials were all anatase TiO₂.The crystallinity and particle size of nano-TiO₂ were greatly affected by hydrothermal temperature and titanium-urea ratio,and were less affected by Ti?SO₄?₂concentration,and the optimum particle size was 11.8 nm.Since N and some Sm elements were not doped into the TiO₂ lattice,the particle size of TiO₂ was increased,so Sm-TiO₂ and Sm-N-TiO₂ did not enhance the photocatalytic performance of nano-TiO₂.In summary,the prepared material TiO₂ has photocatalytic properties under simulated sunlight,and the photocatalytic/aged-waste-based bioreactor combination process has a good development prospect on the old leachate treatment.