Willow Woodlot Leachate Treatment
In partnership with the Ecowaste Landfill, SYLVIS developed an innovative soil-plant treatment system for the leachate produced at the landfill. Landfill leachate is formed when rain water flows through a landfill and takes up organic and inorganic constituents from the landfill contents, producing a liquid that contains elevated levels of pollutants such as ammonia nitrogen and suspended solids. An underground piping system collects the leachate, bringing it to a collection pond for treatment.
The Ecowaste soil-plant land treatment system consisted of fabricated topsoil placed on four closed landfill cells and planted with coppice willows, hybrid poplars, or forage grasses. Leachate was delivered to the soil-plant system through an irrigation system. The vegetation took up nutrients and water from the leachate and the fabricated soil provided additional removal of nutrients, suspended solids, and trace elements. The primary goal of the Ecowaste soil-plant leachate treatment program was to maximize the treatment and use of the leachate, resulting in improved leachate quality and reduced discharge to surface waters.
As a fast-growing tree species capable of rapid nutrient and water uptake, coppicing willows were a vital component of the landfill leachate treatment system. Hybrid willows were planted in high density plantations and were harvested every three years. The plantations may last up to 30 years resulting in nine to ten harvests from a single planting. SYLVIS researched the ideal soil formulation and selected the variety of coppicing willows with the highest performance potential for the site conditions. SYLVIS carried out the plantation establishment including soil fabrication, soil placement, and planting of the willows, and managed the irrigation, maintenance, and harvest of the willow biomass in coordination with the entire leachate treatment system at the Ecowaste Landfill.
The willow woodlot provided Ecowaste with an effective leachate treatment system and provided secondary benefits such as improved aesthetics of the landfill and production of valuable biomass. The willow woodlot consistently reduced the levels of contaminants in the leachate to meet the discharge parameters outlined in the Ecowaste Landfill operational certificate and the harvested biomass was successfully used by the Ecowaste Landfill at their composting facility.