achate collection was assumed active throughout the entire 100- year time period of the assessment; however, a worst case situation was considered assuming a progressive deterioration of the bottom liner performance. This resulted in decreasing leachate collection efficiency over time: from 95% efficiency during the first 20 years to 60% the last 25 years. The first 50 years all collected leachate was assumed to be treated at a wastewater treatment plant (WWTP), in the latter period all collected leachate was assumed to be discharged directly to the sea. Sludge from the WWTP (containing the removed heavy metals) was assumed distributed at fields and the heavy metals accordingly ending up as soil emissions. The WWTP was not assumed to be 100% efficient and specific heavy metals removal efficiencies were applied in the WWTP based on Manfredi and Christensen
(2009). The heavy metals not removed at the WWTP were assumed discharged to surface waters, whereas heavy metals in the non- collected leachate ended up in the groundwater (Manfredi and Christensen, 2009).
Air emissions from the specific thermal treatment processes (Scenarios 6 and 7) were not available but were instead estimated based on element transfer coefficients for typical waste incinerators (i.e. fractions of an element in the input emitted to air, see Riber et al.,
2008). The solid composition of the APC residues as shown in Table 2 was used as input. In Scenario 7, the residues were co-treated with automobile shredder residues and the transfer coefficients were applied to this mixture. The transfer coefficients were within the range 0–0.35 corresponding to incineration in a modern MSW incinerator (Riber et al., 2008; Pedersen et al., 2009).
Electricity and heat consumed or substituted within the scenarios were assumed to be produced at combined heat and power plants using coal as fuel. Assumptions regarding energy may potentially be important; however the choice of coal as fuel for energy production follows common practice within LCA (for further details, refer to Fruergaard et al., 2009). The emissions and fuel consumptions at these plants were typical for Danish conditions and allocated based on energy quality, i.e. based on an assumption that electricity has a higher quality than heat and
4675
thereby associated with a relatively larger share of the emissions and fuel consumption (Fruergaard et al., 2009). The environmental load of electricity generation was thereby approximately six times higher than heat generation. Energy and resource consumption/ substitut
achate collection was assumed active throughout the entire 100- year time period of the assessment; however, a worst case situation was considered assuming a progressive deterioration of the bottom liner performance. This resulted in decreasing leachate collection efficiency over time: from 95% efficiency during the first 20 years to 60% the last 25 years. The first 50 years all collected leachate was assumed to be treated at a wastewater treatment plant (WWTP), in the latter period all collected leachate was assumed to be discharged directly to the sea. Sludge from the WWTP (containing the removed heavy metals) was assumed distributed at fields and the heavy metals accordingly ending up as soil emissions. The WWTP was not assumed to be 100% efficient and specific heavy metals removal efficiencies were applied in the WWTP based on Manfredi and Christensen(2009). The heavy metals not removed at the WWTP were assumed discharged to surface waters, whereas heavy metals in the non- collected leachate ended up in the groundwater (Manfredi and Christensen, 2009).Air emissions from the specific thermal treatment processes (Scenarios 6 and 7) were not available but were instead estimated based on element transfer coefficients for typical waste incinerators (i.e. fractions of an element in the input emitted to air, see Riber et al.,2008). The solid composition of the APC residues as shown in Table 2 was used as input. In Scenario 7, the residues were co-treated with automobile shredder residues and the transfer coefficients were applied to this mixture. The transfer coefficients were within the range 0–0.35 corresponding to incineration in a modern MSW incinerator (Riber et al., 2008; Pedersen et al., 2009).Electricity and heat consumed or substituted within the scenarios were assumed to be produced at combined heat and power plants using coal as fuel. Assumptions regarding energy may potentially be important; however the choice of coal as fuel for energy production follows common practice within LCA (for further details, refer to Fruergaard et al., 2009). The emissions and fuel consumptions at these plants were typical for Danish conditions and allocated based on energy quality, i.e. based on an assumption that electricity has a higher quality than heat and4675thereby associated with a relatively larger share of the emissions and fuel consumption (Fruergaard et al., 2009). The environmental load of electricity generation was thereby approximately six times higher than heat generation. Energy and resource consumption/ substitut
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