Water hyacinth system for municipal landfill leachate treatment

Batch experiments were conducted in a green house environment to investigate the ability of water hyacinth (Eichhornia crassipes) to treat municipal landfill leachate. The experiments were carried out on leachate samples collected from Essex-Windsor Regional Landfill, Windsor, Ontario, Canada. Three leachate dilutions were used in the study. In addition to plant growth, leachate constituents such as pH, alkalinity, chemical oxygen demand (COD), ammonia, total Kjeldahl nitrogen (TKN), nitrate, reactive phosphate, total iron, potassium and chloride were also determined. These parameters were analyzed at different times covering the duration of the experiments. The experimental data showed that water hyacinth system was capable of reducing total nitrogen in the leachate. The pH level remained around 8.0. High consumption of alkalinity during the first three weeks was observed, which could be attributed to nitrification of ammonia. Ammonia nitrogen and total reactive phosphate were removed completely, whereas potassium and chloride remained unchanged. Landfill leachate has a negative impact on plant growth. As the concentration of leachate increases, its toxicity increases resulting in the decrease in the growth of water hyacinth. Water hyacinth system seems to be a promising technology for treating municipal landfill leachate. However, additional studies are required to investigate the system tolerance for some pollutants that might be present in leachate at wide ranges of concentrations such as salinities, hydrogen ion concentration, and heavy metals. (author)