Removal of Iron (Fe) from Landfill Leachate Using Horizontal and Vertical Subsurface Flow Constructed Wetland System Planted With Limnocharis Flava

Heavy metals are common environmental pollutants contained in landfill leachate. Metal contamination of soils and waters has a severe impact on the environment and human health. The main purpose of this study was to compare the efficiency of horizontal subsurface flow system (HSSF) and vertical subsurface flow system (VSSF) in the removal of heavy metal (Fe) in landfill leachate. This is done by measuring the amount of Fe accumulated and retained in the plant’s root and aerial part (stem and leaves) and also in the soil media. A laboratory-scale study was conducted on subsurface flow constructed wetland systems operated in vertical and horizontal mode. Each system comprises of one planted system and one control system. The planted systems namely HP and VP were planted with Limnocharis flava, while the control systems namely HC and VC were left unplanted. The systems operated identically at a flow rate of 0.029 m3/d and hydraulic retention times of 24.1 hours and 19.7 hours in HSSF and VSSF systems, respectively. From this study, both vertical subsurface flow and horizontal subsurface flow constructed wetland system performed well in the removal of Fe from landfill leachate with the overall removal efficiency ranging from 91.51 - 99.20%. Although, both systems (VSSF and HSSF) exhibit high removal efficiency, HSSF systems have the upper edge with higher removal efficiency as compared to VSSF system, which is due to the higher HRT value of HSSF systems. As conclusion, the HSSF system is more suitable to be used for the treatment of landfill leachate which contains high heavy metal as compared to the VSSF system. This finding also shows the suitability of Limnocharis flava to be used in constructed wetlands to treat landfill leachate.