ABSTRACT
The Huneault Landfill, located in Gloucester, Ontario, has been in operation since the early 1960s. Since 1971, this landfill has received industrial, commercial, and institutional (IC&I) wastes, as well as construction/demolition materials. The landfill produces an estimated 57 000 m/year of leachate, which is distinctly different from most landfill leachates in Ontario and which is attributed to the type of waste landfilled at this site. An engineered wetland system consisting of a vertical flow peat filter followed by three surface-flow (SF) wetlands was selected as the leachate treatment method before discharging this effluent into the receiving environment. The engineered wetland treatment system came into operation in August 1995. Leachate is collected in two retention ponds and then pumped and distributed over the peat filter by way of spray irrigation. The filtrate is then collected at the bottom by a network of subsurface drain systems that flow into the three SF wetlands. The peat filter has a surface area of 5580 m and depth of 1.4 m. The three engineered SF wetland cells operate in series with a total surface area of 4374 m. Field monitoring of the engineered wetland system demonstrates that this system is very effective in treating landfill leachate. Removal efficiencies for some of the selected parameters were 95, 58, and 90% for NH3, total organic carbon (TOC), and boron, respectively.
