title: Improvement of wheat straw anaerobic digestion through alkali pre-treatment: Carbohydrates bioavailability evaluation and economic feasibility.
abstract: Lignocellulosic biomasses such as wheat straw are widely used as a feedstock for biogas production. However, these biomasses are mainly composed of a compact fibre structure and therefore, it is recommended to treat them prior to its usage for biogas production in order to improve their bioavailability. The aim of this work is to evaluate, in terms of performance stability, methane yield and economic feasibility, two different scenarios: a mesophilic codigestion of wheat straw and animal manure with or without a low-energy demand alkaline pre-treatment (0.08gKOHgTS-1of wheat straw, for 24h and at 25°C). Besides this, said pre-treatment was also analysed based on the improvement of the bioavailable carbohydrate content in the untreated versus the pre-treated wheat straw. The results pointed out that pre-treated wheat straw prompted a more stable performance (in terms of pH and alkalinity) and an improved methane yield (128% increment) of the mesophilic codigestion process, in comparison to the "untreated" scenario. The pre-treatment increased the content of cellulose, hemicellulose and other compounds (waxes, pectin, oil, etc.) in the liquid fraction, from 5% to 60%, from 11.5% to 39.1% TS and from 57% to 79% of the TS in the liquid fraction for the untreated and pre-treated wheat straws, respectively. Finally, the pre-treated scenario gained an energy surplus of a factor 13.5 and achieved a positive net benefit of 90.4€tVS-WS-1d-1, being a favourable case for an eventual scale-up of the combined process.
authors.affiliation: IRTA, GIRO-UPC Joint Unit, Torre Marimon, Road C59- km 12, E 08140 Caldes de Montbui, 08140 Barcelona, Spain.
authors.forename: Maycoll Stiven
authors.initials: MS
authors.lastname: Romero-Güiza
authors.affiliation: Department of Engineering, Aarhus University, Blichers Allé 20, DK 8830 Tjele, Denmark; Faculty of Chemical Engineering, Universiti Teknologi Mara, 40450 Shah Alam, Malaysia.
authors.forename: Radziah
authors.initials: R
authors.lastname: Wahid
authors.affiliation: Department of Engineering, Aarhus University, Blichers Allé 20, DK 8830 Tjele, Denmark.
authors.forename: Verónica
authors.initials: V
authors.lastname: Hernández
authors.affiliation: Department of Engineering, Aarhus University, Blichers Allé 20, DK 8830 Tjele, Denmark.
authors.forename: Henrik
authors.initials: H
authors.lastname: Møller
authors.affiliation: IRTA, GIRO-UPC Joint Unit, Torre Marimon, Road C59- km 12, E 08140 Caldes de Montbui, 08140 Barcelona, Spain. Electronic address: belen.fernandez@irta.cat.
authors.forename: Belén
authors.initials: B
authors.lastname: Fernández
keywords: Alkali pre-treatment; Anaerobic co-digestion; Pig manure; Potassium hydroxide; Wheat straw