title: Environmental assessment of farm-scaled anaerobic co-digestion for bioenergy production.
abstract: The aim of this study was to assess the environmental profile of a bioenergy system based on a co-digestion plant using maize silage and pig slurry as substrates. All the processes involved in the production of bioenergy as well as the avoided processes accrued from the biogas production system were evaluated. The results evidenced the environmental importance of the cultivation step and the environmental credits associated to the avoided processes. In addition, this plant was compared with two different plants that digest both substrates separately. The results revealed the environmental benefits of the utilisation of pig slurry due to the absence of environmental burdens associated with its production as well as credits provided when avoiding its conventional management. The results also presented the environmental drawbacks of the utilisation of maize silage due to the environmental burdens related with its production. Accordingly, the anaerobic mono-digestion of maize silage achieved the worst results. The co-digestion of both substrates was ranked in an intermediate position. Additionally, three possible digestate management options were assessed. The results showed the beneficial effect of digestate application as an organic fertiliser, principally on account of environmental credits due to avoided mineral fertilisation. However, digestate application involves important acidifying and eutrophicating emissions.
authors.affiliation: Department of Chemical Engineering, Institute of Technology, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain. Electronic address: lucia.lijo@usc.es.
authors.forename: Lucía
authors.initials: L
authors.lastname: Lijó
authors.affiliation: Department of Chemical Engineering, Institute of Technology, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain.
authors.forename: Sara
authors.initials: S
authors.lastname: González-García
authors.affiliation: Department of Agricultural and Environmental Sciences, Production, Landscape, Agroenergy, University of Milan, Milan, Italy.
authors.forename: Jacopo
authors.initials: J
authors.lastname: Bacenetti
authors.affiliation: Department of Agricultural and Environmental Sciences, Production, Landscape, Agroenergy, University of Milan, Milan, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Negri
authors.affiliation: Department of Agricultural and Environmental Sciences, Production, Landscape, Agroenergy, University of Milan, Milan, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Fiala
authors.affiliation: Department of Chemical Engineering, Institute of Technology, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain.
authors.forename: Gumersindo
authors.initials: G
authors.lastname: Feijoo
authors.affiliation: Department of Chemical Engineering, Institute of Technology, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain.
authors.forename: María Teresa
authors.initials: MT
authors.lastname: Moreira
mesh_terms: D000693:Anaerobiosis; D000818:Animals; D056804:Biofuels / Q000032:analysis*; D012722:Sewage / Q000737:chemistry*; D012820:Silage; D013552:Swine; D003313:Zea mays
chemical_list: D056804:Biofuels; D012722:Sewage
keywords: Digestate management; Environmental profile; Life cycle assessment; Maize silage; Pig slurry