title: LCA of management strategies for RDF incineration and gasification bottom ash based on experimental leaching data.
abstract: The main characteristics and environmental properties of the bottom ash (BA) generated from thermal treatment of waste may vary significantly depending on the type of waste and thermal technology employed. Thus, to ensure that the strategies selected for the management of these residues do not cause adverse environmental impacts, the specific properties of BA, in particular its leaching behavior, should be taken into account. This study focuses on the evaluation of potential environmental impacts associated with two different management options for BA from thermal treatment of Refuse Derived Fuel (RDF): landfilling and recycling as a filler for road sub bases. Two types of thermal treatment were considered: incineration and gasification. Potential environmental impacts were evaluated by life-cycle assessment (LCA) using the EASETECH model. Both non-toxicity related impact categories (i.e. global warming and mineral abiotic resource depletion) and toxic impact categories (i.e. human toxicity and ecotoxicity) were assessed. The system boundaries included BA transport from the incineration/gasification plants to the landfills and road construction sites, leaching of potentially toxic metals from the BA, the avoided extraction, crushing, transport and leaching of virgin raw materials for the road scenarios, and material and energy consumption for the construction of the landfills. To provide a quantitative assessment of the leaching properties of the two types of BA, experimental leaching data were used to estimate the potential release from each of the two types of residues. Specific attention was placed on the sensitivity of leaching properties and the determination of emissions by leaching, including: leaching data selection, material properties and assumptions related to emission modeling. The LCA results showed that for both types of BA, landfilling was associated with the highest environmental impacts in the non-toxicity related categories. For the toxicity related categories, the two types of residues behaved differently. For incineration BA the contribution of metal leaching to the total impacts had a dominant role, with the highest environmental loads resulting for the road scenario. For the gasification BA, the opposite result was obtained, due to the lower release of contaminants observed for this material compared to incineration BA. Based on the results of this study, it may be concluded that, depending on the type of BA considered, its leaching behavior may significantly affect the results of a LCA regarding its management strategies.
authors.affiliation: Laboratory of Environmental Engineering, Department of Civil Engineering and Computer Science Engineering, University of Rome "Tor Vergata", Via del Politecnico 1, 00133 Rome, Italy.
authors.forename: Martina
authors.initials: M
authors.lastname: Di Gianfilippo
authors.affiliation: Laboratory of Environmental Engineering, Department of Civil Engineering and Computer Science Engineering, University of Rome "Tor Vergata", Via del Politecnico 1, 00133 Rome, Italy. Electronic address: costa@ing.uniroma2.it.
authors.forename: Giulia
authors.initials: G
authors.lastname: Costa
authors.affiliation: Laboratory of Environmental Engineering, Department of Civil Engineering and Computer Science Engineering, University of Rome "Tor Vergata", Via del Politecnico 1, 00133 Rome, Italy.
authors.forename: Sara
authors.initials: S
authors.lastname: Pantini
authors.affiliation: Department of Environmental Engineering, Technical University of Denmark, Building 113, DK-2008 Kgs. Lyngby, Denmark.
authors.forename: Elisa
authors.initials: E
authors.lastname: Allegrini
authors.affiliation: Laboratory of Environmental Engineering, Department of Civil Engineering and Computer Science Engineering, University of Rome "Tor Vergata", Via del Politecnico 1, 00133 Rome, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Lombardi
authors.affiliation: Department of Environmental Engineering, Technical University of Denmark, Building 113, DK-2008 Kgs. Lyngby, Denmark.
authors.forename: Thomas Fruergaard
authors.initials: TF
authors.lastname: Astrup
mesh_terms: D060729:Coal Ash / Q000032:analysis*; D005740:Gases / Q000737:chemistry*; D017745:Incineration; D012989:Soil Pollutants / Q000032:analysis*; D062611:Solid Waste / Q000032:analysis*
chemical_list: D060729:Coal Ash; D005740:Gases; D012989:Soil Pollutants; D062611:Solid Waste
keywords: Bottom ash; Gasification; Incineration; Leaching; Life cycle assessment; Refuse derived fuel