Removal of ammoniacal nitrogen and oxidised nitrogen in landfill leachate using vegetated constructed wetland with continuous flow through different filter media

Performance of the vegetated horizontal subsurface-flow constructed wetland was evaluated for the removal of ammoniacal nitrogen (AN), total oxidized nitrogen (TNOx-N) and nitrite nitrogen (NO₂-N) from landfill leachate. Four reactors were used, RI (granite without vegetation), RII and RIII which consists of granite and gravel with different sizes respectively and RIV contained sand and 67.5 L of charcoal. RII, RIII and RIV were planted with cattails. The leachate obtained from the site of Pulau Burung Sanitary Landfill, Penang was introduced into RI at flow rate of 18 mL/min which was continuous to flow through another three reactors. The leachate was analyzed for AN, TNOx-N and NO₂-N before and after the treatment in each reactor by standard methods. The overall average removal efficiency of AN and NO₂-N were 86.7 % and 19.5 % respectively but negative effect to TNOx-N which was -16.3 %. The negative result shows the increased in the concentration of TNOx-N. Reactor IV performed the best for removal of AN and NO₂-N which is 60.9 % and 66.2 % respectively, whereas, RII had highest performance for removal of TNOx-N of 24.1%.