Research On Treating The Landfill Leachate With Men-constructed Wetland

Landfill leachate was one of organic sewages with the higher concentrations and complicated compositions of pollutants, and difficult to be biodegraded. The traditional method treaded it was short in low removal efficiency or the higher treating costs while treating it with men-constructed wetland had advantages in removing stable efficiency, the stronger resistance to impact of high pollution load and treating low costs, on the like. However, it was still not so perfect and its removing efficiency unsatisfactory currently, it is must be necessary for further research in the fields.The programme:(1) main characteristics of plants, soils and interaction between them were analyzed for choosing the appropriate wetland plants. (2) men-constructed wetland was built for treating the leachate with the methods of drip irrigation and furrow irrigation, and evaluated the treatment ability.The results showed that:(1) The coverage and biomass of Phragmites communi, Rumex cetosa and Artemisia argy were significant higher than other plants and their roots loosed the soil with the particle-size of 0.9-4.Omm and the uptake of carbon and nitrogen in the soil by them were significant higher than the others'. Phragmites communi was the right one to be cultivated, and the other two wild plants near the wetland should be kept at a certain number. (2) A significant preferential flow was produced in the nature soil, but in the sieved soil, it remained as a steady seepage. The water capacity and HRT in the nature soil were both significant lower than those in the sieved soil. The displacement and velocity of wetting front were significant correlated with the time. (3) Method of drip irrigation:The ways of reducing the pollution load and reflowing improved the removal of the pllutants significantly. The removal efficiency of the COD and SS were 43.6-63.3 and 49.6-67.3%. (4) Method of furrow irrigation:When the volume irrigation of the two water were both the same, the average hydraulic loading and HRT of clean water were 1450 m3/(ha·d) and 23.3 hours while those of leachate were 1700 m3/(ha-d) and 19.9 hours. The average removal efficiency of the COD, TOC and TN were 70.4,70.1 and 30.2%.Therefore, the constructed wetland removed the pllutants in the landfill leachate stably, but low on that of TN, so it was necessary to research on improving this area for promoting the leachate treatment with wetlands.