Comparison of the Landfill Disposal Options for Bottom and Fly Ash Fractions from an Industrial-Scale (120 MW) Power Plant Incinerating Different Fuel Mixtures

摘要

In this study, we determined the leachable concentrations of As, Ba, Cd, Cr, Cu, Hg,Ni, Pb, Mo, Sb, Se, Zn, chloride, fluoride, sulphate and DOC in two types of bottom ash and flyash fractions [(BA(1) and FA(1); Fuels: 50% peat, 25% coal, 25% wood residues) and (BA(2)and FA(2); Fuels: 50% peat, 50% forest residues)] from a large-sized (120 MW) bubblingfluidized bed boiler. The bottom ash BA(1) and bottom ash BA(2) can be disposed of in an inertwaste landfill. However, in the fly ash FA(1), the leachable concentration of Mo (3.9 mg kg~(-1);d.w) and Se (0.17 mg kg~(-1); d.w.) exceeded the limit values for the acceptance of waste at inertwaste landfill. Therefore, this residue may be disposed in a non-hazardous waste landfill. In thefly ash FA(2), the leachable concentration of Mo (3.2 mg kg~(-1); d.w.) exceeded the limit valuesfor the acceptance of waste at an inert waste landfill. Therefore, this residue may be disposed innon-hazardous waste landfill. In this context it is worth noting that, although the leachedconcentrations of Mo and Se exceeded the limit values for an inert waste landfill, according tothe Finnish legislation, which is based on EU directives and regulations, the competentenvironmental authority may decide that the maximum limit values can be up to three timeshigher on the basis of the local environmental conditions in a landfill. In spite of this possibilityfor the environmental authorities to relax the minimum limit values for Mo and Se, the fly ashfraction FA(1) and fly ash fraction FA(2) investigated in this study cannot be deposited in inertwaste landfill according to local policy decisions with respect to relaxation. It is worth notingthat in this study we have only determined whether the bottom ash fractions BA(1) and BA(2), aswell as fly ash fractions FA(1) and FA(2) may be disposed of either to an inert waste, a nonhazardouswaste or a hazardous waste landfill site. We could like to point out that according tothe Finnish legislation the utilizations of these residues are still possible. However, then anenvironmental permit is required.