title: Environmental assessment of mild bisulfite pretreatment of forest residues into fermentable sugars for biofuel production.
abstract: BACKGROUND
  Sugar production via pretreatment and enzymatic hydrolysis of cellulosic feedstock, in this case softwood harvest residues, is a critical step in the biochemical conversion pathway towards drop-in biofuels. Mild bisulfite (MBS) pretreatment is an emerging option for the breakdown and subsequent processing of biomass towards fermentable sugars. An environmental assessment of this process is critical to discern its future sustainability in the ever-changing biofuels landscape.
  
  
  RESULTS
  The subsequent cradle-to-gate assessment of a proposed sugar production facility analyzes sugar made from woody biomass using MBS pretreatment across all seven impact categories (functional unit 1 kg dry mass sugar), with a specific focus on potential global warming and eutrophication impacts. The study found that the eutrophication impact (0.000201 kg N equivalent) is less than the impacts from conventional beet and cane sugars, while the global warming impact (0.353 kg CO2 equivalent) falls within the range of conventional processes.
  
  
  CONCLUSIONS
  This work discusses some of the environmental impacts of designing and operating a sugar production facility that uses MBS as a method of treating cellulosic forest residuals. The impacts of each unit process in the proposed facility are highlighted. A comparison to other sugar-making process is detailed and will inform the growing biofuels literature.
authors.affiliation: Department of the Environment and Forest Sciences, University of Washington, Box 351750, Seattle, WA 98195 1750 USA.
authors.forename: Ikechukwu C
authors.initials: IC
authors.lastname: Nwaneshiudu
authors.affiliation: Department of the Environment and Forest Sciences, University of Washington, Box 351750, Seattle, WA 98195 1750 USA.
authors.forename: Indroneil
authors.initials: I
authors.lastname: Ganguly
authors.affiliation: Department of the Environment and Forest Sciences, University of Washington, Box 351750, Seattle, WA 98195 1750 USA.
authors.forename: Francesca
authors.initials: F
authors.lastname: Pierobon
authors.affiliation: Department of the Environment and Forest Sciences, University of Washington, Box 351750, Seattle, WA 98195 1750 USA.
authors.forename: Tait
authors.initials: T
authors.lastname: Bowers
authors.affiliation: Department of the Environment and Forest Sciences, University of Washington, Box 351750, Seattle, WA 98195 1750 USA.
authors.forename: Ivan
authors.initials: I
authors.lastname: Eastin
keywords: Biofuels; Biomass; Life cycle assessment; Pretreatment