Comparative Study on the Landfill Leachate Treatment in a Vertical Flow Wetland System With/Without Phragmites australis

The landfill leachate treatment efficiency in a vertical-flow wetland system with and without planted Phragmites australis was investigated. The BOD/COD ratio of the landfill leachate was 0.38. Water samples were taken daily for determination of the COD, BOD, [NH4-N], [NO2-N], [NO3-N] and orthophosphates values. High COD and BOD removal efficiencies and discharge limits in both laboratory systems were achieved. Complete elimination of the ammonium nitrogen from the leachate in the nonvegetated wetland for 13 and 14 days was obtained at a recirculation ratio of 1:1 and 1:2, respectively, and for 9 and 7 days - in the vegetated wetland, at the same recirculation ratios. The initial nitrite nitrogen concentration in the landfill leachate was 17.2 ± 1.1 mg/L, which is 430 times over the discharge limit for these ions. After landfill leachate treatment in the nonvegetated wetland system at the recirculation ratios 1:1 and 1:2, nitrites removal efficiencies of 98.8% and 92.5%, respectively, were achieved. In the vegetated wetland system at the same recirculation ratios, nitrites removal efficiencies of 96.5% and 76.2%, respectively were achieved. Nitrates removal was not observed. The results show that the orthophosphates were assimilated better from the Phragmites australis at longer water resting period.