Not long ago, the first case of illegal dumping of landfill leachate and caused environmental pollution of Yunnan which has caused much concern has been adjudged; the defendant because of surrender and pleaded guilty with a good attitude, has jailed for 2 years and will respite for 2 years, also he was imposed a fine of 20,000 and do some service as a environment volunteer. It is reported that this case is because the defendant privately dumped his transportation of 29 cars which totaled 568.34 tons of pollutants into the environment, under the case of known the heavy metals, organic compounds should be transported to a special institution for professional treatment, and thus caused serious pollution to the surrounding environment. In this regard, the court verdict this case based on the principle of "spoiler repairs, polluter controls".

 

Landfill leachate is the high concentration of organic or inorganic ingredients liquid which generates from the landfill garbage piling up in the biochemical degradation process due to compaction, fermentation, etc., while in precipitation and groundwater seepage produces liquid comprising. In the biological pretreatment process, titanium dioxide photocatalyst has been used in the degradation of landfill leachate, and the experiments showed that this is a successful method for cleaning leachate. In addition, the experimental has derived the factors which influence photocatalytic oxidation process of landfill leachate, they are photocatalyst dosage, pH value, light intensity, illumination time and oxygen content dissolved in the water ect..

 

Tungsten trioxide (WO₃), a yellow powder, the large number of it is used for the production of metal tungsten; in addition, WO₃ has the property of semiconductor, with the band gap of 2.4eV ~ 2.8eV. WO₃ as a photocatalyst can response to visible light, thus to fully use the solar energy, instead of relying on the ultraviolet light, such as titanium dioxide. Photocatalytic activity is a common decision of the ability of absorbing light, charge separation and the transferring efficiency to the substrate. WO3 has a wider spectral response capability, to this point of view, it should have a stronger catalytic oxidation than titanium dioxide, and can be used for landfill leachate degradation. In addition, studies have shown that yttrium (Y⁺) doped WO₃ photocatalyst can improve the ability to absorb light, thus improve the photocatalytic activity of the system.