page_title: Nantmel Landfill Site
section_title: Leachate treatment
hierarchical_section_title: Nantmel Landfill Site / Leachate treatment
caption_attribution_description: English: Students from Aberystwyth University view the leachate lagoon at Nantmel landfill site, Powys. (Photo taken from on top of the biofilm tower) Français&#160;: Étudiants de l'Université d'Aberystwyth visitant la lagune de traitement des lixiviats du site d'enfouissement Nantmel, Powys. (photo prise du sommet d'une Tour à biofilm ("Biofilm tower") qui favorise un biofilm aérobie devant dégrader la plupart des composés organiques, fixer les ions métalliques en formes oxydés ou insolubles (par exemple, en transformant le fer ferreux en fer ferrique), oxyder l'Ammoniaque (via une phase nitrite) en nitrate, précipiter d'autres métaux que l'on retrouvera dans les boues de la lagune sous forme d'hydroxydes ferriques (source).
context_page_description: Nantmel Landfill Site is a closed waste-disposal site situated in the community of Nantmel, Llandrindod Wells, Powys, Wales. It operated from 1960 to 1990, accepting domestic, commercial, non-hazardous industrial, inert and asbestos waste. It was one of 80 municipal landfill sites in Powys, of which all have now closed. Three privately owned sites still operate within the county. The site still produces significant pollutants, in the form of gas and leachate from landfill decomposition, and is currently undergoing rehabilitation.
context_section_description: Initially the leachate was managed to the 'dilute and disperse principle', producing up to 600 tonnes of leachate a day. This cost the council £330,000 per annum to remove in tankers to Hereford. In 1996 the installation of an on-site treatment system means costs are now just £65,000 per annum, a move commended by the Environment Agency.
  The current system (detailed in) consists of an S3 Environmental Solutions Ltd nitrification tower (a trickling filter also known as an aeration or biofilm tower) through which the leachate is circulated over a biofilm supported on a plastic media. The partially treated leachate then leaves behind iron-rich sludge in the leachate lagoon (visibly stained orange; see photo to the left and satellite images) and is polished in a series of reed and gravel filter beds and a wetland system. By this point the leachate meets water quality levels, and so can be released into the river system.
  The tower maintains aerobic conditions, favourable for the biofilm within, which allows: 
  the degradation of organic components,
  metallic ions to be oxidised to insoluble forms (e.g. ferrous iron to ferric iron),
  ammonia to be oxidised (via nitrite) to nitrate,
  remaining metals to precipitate into the lagoon sludge with ferric hydroxides.
  Among other pollutants, this system removes the leachate's high Biological Oxygen Demand, the ammoniacal nitrogen and ferrous iron contents.
caption: Students from Aberystwyth University view the leachate lagoon (Photo from top of Nitrification tower)
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