| Treatments of landfill leachate with constructed wetlands are studied in the article. Constructed wetlands, including horizontal subsurface constructed wetland and vertical subsurface constructed wetland, are used as post treatment unit of old leachate and pretreatment unit of young leachate, through the test and research, the feasibility, difference, and remove effect to the pollutant of constructed wetlands can be ascertained.To the post treatment of landfill leachate with constructed wetland, two conditions are tested, one hydraulic retention time (HRT) is 40 days, the other is 15 days. The results showed: (1) On the two conditions, for the remove effects to the pollutant, horizontal subsurface constructed wetlands is a litter better than vertical subsurface wetlands. (2) Pollutant is removed gradually along leachate current, and removal velocity is faster in the foreside than rearward. (3) The removal effects of HRT=40d is obviously better than HRT=15d. (4) COD,NH4+-N, TN, TP, SS and heavy metal are inspected in the test. On the condition of HRT=40d, except COD. the others all meet Emission Standards I . On the condition of HRT=15d, COD and NH4+-N are far higher than Emission Standards ll but removal efficiency is still better than 70%. (5) On the two conditions, removal efficiencies of Cr,Cu,Zn, Fe are well to meet Emission Standards I for two kinds of constructed wetlands, while which cannot remove Pb.To the pretreatment of young landfill leachate with constructed wetlands, two different conditions are tested, surface hydraulic loads are respectively 8 L/m2? d and 16 L/m2 ? d, but with the same volume organic load. The results showed: (1) Removal efficiency is not obviously different to two different kinds wetlands. (2) Pollutant is removed and removal velocity reduced gradually along leachate current. (3) On two different conditions, removal efficiency is same. Removal efficiencies of COD and BOD are 60-70%, and NH4+-N is about 85% and TN is 75%, which all not meet Emission Standards Il. Removal efficiencies of SS and TP are above 80%, and Cr,Cik Zik Fe are higher than 90%, which all meet Emission Standards I . (4) Biodegradability of landfill leachate is improved and increased 15%.The research results showed: constructed wetlands can be used as pretreatment unit and post treatment unit to landfill leachate, and horizontal and vertical subsurface constructed wetlands have no obviously difference, whose removal efficiency to pollutant is very well.
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