Selection of macrophytes and substrates to landfill leachate treatment using vertical flow constructed wetlands

CAMAÑO SILVESTRINI, N.; SANCHEZ, G.C.; GONZALEZ, C.I.; MAINE, M.A.; HADAD, H.R.; PEDRO, M.C.; CAFFARATTI, S.

York

Simposio; 6th International Symposium on Wetland Pollutant Dynamics and Control-WETPOL 2015; 2015

Constructed Wetland Association

The chemical composition of landfill leachate depends on waste composition, climatic condition, and the age and degradation rate of the solid waste. Ammonium is one of the main contaminants of landfill leachate, due to organic matter anaerobic degradation. Vertical subsurface flow constructed wetlands posses high ability to oxidize the ammonia nitrogen (Kadlec and Zmarthie, 2010). Macrophytes and media play an important role in the removal of pollutants (Cooper, 1999). The aim of this study was to evaluate the macrophytes and substrates suitable to be used in a vertical subsurface flow wetlands (VFW) constructed for the treatment of a landfill leachate. Real landfill leachate was used during all the experiments. Microcosm-scale reactors simulating vertical subsurface flow wetlands (VF) were disposed in a greenhouse. Substrate selection was achieved using different layers of: Leca, coarse sand, fine sand and gravel. Different macrophytes (T.domingensis, S.californicus, I. pseudoacorus, P. elephantipes and S. montevidiensis) were studied to assess their tolerance to the pre-treated, the raw and a diluted raw leachate. In a second stage, mesocosm-scale reactors were disposed with the selected substrate and planted with T.domingensis and I. Pseudoacorus (Fig 1). Unplanted reactors were also disposed. During 30 days, 10% diluted landfill leachate was poured in the reactors. Then, 20% diluted landfill leachate was treated in the reactors. pH, Conductivity, NH4+ , NO3- , COD and BOD were measured as described in APHA (1998) in the leachate before and after the treatment in each reactor. Experiment lasted three months. Macrophyte growth was also measured. All species tolerated pre-treated and 10% and 20% diluted landfill leachate. Significant removal of ammonium, nitrate, BOD, COD and SRP were obtained. T. domingensis and I. pseudoacorus could be used for removing contaminants from a diluted landfill leachate. Leca and coarse sand are suitable substrates for use in a constructed wetland to treat landfill leachate. Further experiments are carrying out with 30 % diluted landfill leachate.