Treating Landfill Leachate

Combining the filtration, adsorption, and assimilation mechanisms of trickling filters with the innovative use of passive floating treatment wetlands and aeration may be an efficient, cost-effective, and low maintenance pre-treatment process to meet the requirements that are necessary for leachate to be discharged to domestic publicly operated treatment works (POTWs). Landfill leachate management is a challenge that continues into the post-closure period. Managers often pay for leachate treatment by volume, biochemical oxygen demand (BOD) and/or chemical oxygen demand (COD) loading, and nitrogen loading. When wastewater treatment facilities receive loads from significant industrial waste streams, effluent quality can vary due to the complexity of the waste stream. POTWs are increasingly refusing to accept landfill leachate due to elevated concentrations of ammonia, humic acid, total dissolved solids (TDS), chlorides, perfluoroalkyl and polyfluoroalkyl substances (PFAS) and other constituents of potential concern, particularly in the face of increasingly stringent discharge standards in the state of Florida. Ammonia, PFAS, and recalcitrant organic matter are of particular concern for landfills in the state of Florida who discharge to POTWs. Wastewater treatment plants charge landfills a discharge fee based on the leachate volume discharged and concentrations of certain parameters, particularly chemical oxygen demand and nitrogen. Any pre-treatment that can occur prior to discharge to a POTW will lower discharge costs. However, pre-treatment options for landfill leachate that include high-tech solutions with high operation and maintenance costs may not be sustainable at many landfill sites, especially in rural areas. This is especially important for closed landfills which operate under a budget that was projected out for the closing period.

This study explores optimization of low-cost, low-maintenance, floating wetlands with trickling filters and aeration to treat leachate, reducing inorganic nitrogen and COD loading before discharge to POTW. The end goal of this work is to provide design criteria combining the filtration, adsorption, and assimilation mechanisms of trickling filters with the innovative use of passive floating treatment wetlands and aeration so that landfill managers can reduce leachate management costs and meet the requirements that are necessary for leachate to be discharged to domestic POTWs.  

1. Interview Florida landfill operators to optimize feasibility of floating wetlands, aeration, and trickling filter process design, footprint, and cost.
2. Construct and operate three different bench-scale treatment trains with aeration, floating wetlands, and trickling filter unit processes to evaluate and optimize chemical oxygen demand, nitrogen, and metals removal
3. Assess optimal growth cycle for plants in floating treatment wetland to develop operational criteria adn timelines of effectiveness for landfill managers.