Phytoremediation of Landfill Leachate and Peat Filter Treatment in Constructed Wetland

Abstract

It’s universally known that landfills leaking emissions into surroundings have negative environmental impacts and in response to the EC Landfill Directive (1999/31/EC) and later the Waste Directive 2008/98/EC of 19th November 2008, many landfills sites have been forced to close down and many needs remediation. The landfill operator is responsible for the final coverage and after-care control of the site for a period of at least 30 years after the closure. In this case study, Ødegård landfill in Norway (associated member of EU), has received total 600 000 tons of solid waste from automobile shredder and contaminated soil during the period 1992-2009. The leachate is pumped from the collection tank up to a SBR Byggingenjörerna reactor plant for chemical and biological treatment. The residual sludge from the SBR plant is collected in the sludge pit and then returned to the landfill and the treated leachate discharged into the river Drogga. Most of the organic compounds in the raw leachate have concentrations over the emission limit before lead into the SBR treatment and in particular high of pesticides. To investigate the ability of peat to uptake pollutants from the leachate from Ødegård, column tests with ash mixed with peat as filter media were performed. Chemical analyses show a high metal concentration and the discharge of Cu, Ni, Cr and Zn reaching high level over emission limits for the recipient. The aim of the study is to compose purification and treatment steps for leachate in a natural based constructed wetland. The steps include:
 
 Sedimentation basin, straw filter, peat filter, irrigation area of Salix (energy crops),
 Wetland pond with plants for assimilation of contaminants, sand/stone filter,
 Aeration in a water wheel and meandering water into planted wetland pond,From the waterfall the leachate is lead into a sedimentation pond (excavation started summer 2012).