Effect of feeding strategy on the performance of a pilot scale vertical flow wetland for the treatment of landfill leachate

Abstract

Landfill leachate is one of the most challenging types of wastewater to treat using constructed wetlands. The objectiveof this study was to evaluate the effect of two feeding strategies on the treatment efficiency of a landfillleachate using vertical flow wetlands (VFWs) planted with Typha domingensis or Canna indica. The tolerance ofthese macrophytes to the leachate was also evaluated. Coarse sand and light expanded clay aggregates (LECA)were used as substrates. Two feeding strategies (FS) were applied: FSA = 1 pulse per day of 0.21 m pulse−1,FSB = 3 pulses per day of 0.07 m pulse−1. VFWs planted with T. domingensis presented removal efficiencies of34/74% (NH4+) and 16/48% (TN) for FSA/FSB, respectively. VFWs planted with C. indica presented removal efficienciesof 27/72% (NH4+) and 18/46% (TN) for FSA/FSB, respectively. NH4+ and total nitrogen (TN) removal efficiencieswere significantly higher in FSB than in FSA, but there were no significant differences betweenmacrophyte species. COD removal showed no significant differences between FSs or between macrophyte species.T. domingensis and C. indica demonstrated to be tolerant to the leachate studied. VFWs planted withT. domingensis or C. indica are suitable to treat diluted landfill leachate with high ammonium concentrationsusing a feeding strategy of pulses. However, an anaerobic stage may be added after the VFW to get higher TNand COD removal.