Performance of Vertical and Horizontal Subsurface-Flow Constructed Wetlands in Treating Leachate

Leachate treatment is the biggest challenge in landfill management. Improper handling of leachate could lead to various environmental and health problems. In recent years, many researchers have been directed to seek effective yet economic approach in treating leachate. Constructed wetland has been identified as one of the most interesting method in leachate treatment. This natural treatment system is more cost-effective than other conventional approaches. It offers comparable treatment performance at lower installation, operation and maintenance cost. In this study, vegetated vertical subsurface-flow (VF-SSF) and horizontal subsurface-flow (HF-SSF) constructed wetland were designed for the treatment of landfill leachate. Limnocharis flava, which is emergent, hydrophytic vegetation, was planted at the surface of each constructed wetland system. Leachate was continuously circulating through the SSF constructed wetland systems at constant flow rate of 15 ml/min and 5 hrs/cycle hydraulic retention time (HRT) for 18 days. The findings of this study proposed that the removal of nutrients and heavy metals could occur through soil substrates of wetland and/or perform by L.flava bed. Significant improvement in removal efficiency of NH3~N, N03N, Fe and Mn achieved by using VF-SSF and HF-SSF constructed-wetland systems signifies the contribution of L.flava plant in enhancing the overall performance of SSF constructed-wetland system. VF-SSF constructed-wetland system showed higher removal of NH3N and Mn compared to HF-SSF. In contrast, HF-SSF exhibited higher removal of N03N, Fe and P04 3 . Both VF-SSF and HF-SSF could achieve up to 95 % removal of nutrients and more than 80 % of heavy metals presence in leachate.