Möjligheten att minska metallhalten i lakvatten med sulfatreducerande bakterier

Sammanfattning: Anaerobic treatment of landfill leachate using sulphide precipitation was tested at pilot scale for the purpose of heavy metal removal. The emission of leachate is heavily regulated by Swedish authority and the overall concentrations of heavy metals is expected to rise as landfills contain less organic matter. The studied landfill site, located in southern Sweden, needs a robust and economically viable technique to remove metals to concentrations of 80 µg/l and below. The analysed metals were As, Cr, Cu, Fe, Mn, Ni, Pb and Zn. The reactor configuration was an up-flow fixed bed. Two substrates were compared: woodchips and AnoxKaldnes K5 carrier. The reactors were conditioned to promote the growth of sulfate reducing bacteria and suppress the presence of methanogens in order to achieve biological sulphide production. The reactor with Anox carriers led to higher or equivalent metal removal in all cases. Results show that Copper, Iron, Lead, Nickel and Zinc could be removed by up to 52%, 61%, 52%, 22% and 65% respectively. There was no reduction in the concentration of Arsenic, Chromium and Manganese. Final conclusions cannot be drawn; however the technique shows promising results for the treatment of low levels of metals found in leachate using sulphide precipitation.