Ethanol production potential from AFEX™ and steam-exploded sugarcane residues for sugarcane biorefineries

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dc.contributor.authorMokomele, Thapeloen_ZA
dc.contributor.authorDa Costa Sousa, Leonardoen_ZA
dc.contributor.authorBalan, Venkateshen_ZA
dc.contributor.authorVan Rensburg, Eugeneen_ZA
dc.contributor.authorDale, Bruce E.en_ZA
dc.contributor.authorGörgens, Johann F.en_ZA
dc.date.accessioned2018-05-07T05:33:18Z
dc.date.available2018-05-07T05:33:18Z
dc.date.issued2018-05-04
dc.date.updated2018-05-06T03:38:21Z
dc.descriptionCITATION: Mokomele, T., et al. 2018. Ethanol production potential from AFEX™ and steam-exploded sugarcane residues for sugarcane biorefineries. Biotechnology for Biofuels, 11:127, doi:10.1186/s13068-018-1130-z.
dc.descriptionThe original publication is available at https://biotechnologyforbiofuels.biomedcentral.com
dc.description.abstractBackground: Expanding biofuel markets are challenged by the need to meet future biofuel demands and mitigate greenhouse gas emissions, while using domestically available feedstock sustainably. In the context of the sugar industry, exploiting under-utilized cane leaf matter (CLM) in addition to surplus sugarcane bagasse as supplementary feedstock for second-generation ethanol production has the potential to improve bioenergy yields per unit land. In this study, the ethanol yields and processing bottlenecks of ammonia fibre expansion (AFEX™) and steam explosion (StEx) as adopted technologies for pretreating sugarcane bagasse and CLM were experimentally measured and compared for the first time. Results: Ethanol yields between 249 and 256 kg Mg−1 raw dry biomass (RDM) were obtained with AFEX™-pretreated sugarcane bagasse and CLM after high solids loading enzymatic hydrolysis and fermentation. In contrast, StEx-pretreated sugarcane bagasse and CLM resulted in substantially lower ethanol yields that ranged between 162 and 203 kg Mg−1 RDM. The ethanol yields from StEx-treated sugarcane residues were limited by the aggregated effect of sugar degradation during pretreatment, enzyme inhibition during enzymatic hydrolysis and microbial inhibition of S. cerevisiae 424A (LNH-ST) during fermentation. However, relatively high enzyme dosages (> 20 mg g−1 glucan) were required irrespective of pretreatment method to reach 75% carbohydrate conversion, even when optimal combinations of Cellic ® CTec3, Cellic ® HTec3 and Pectinex Ultra-SP were used. Ethanol yields per hectare sugarcane cultivation area were estimated at 4496 and 3416 L ha−1 for biorefineries using AFEX™- or StEx-treated sugarcane residues, respectively. Conclusions: AFEX™ proved to be a more effective pretreatment method for sugarcane residues relative to StEx due to the higher fermentable sugar recovery and enzymatic hydrolysate fermentability after high solids loading enzymatic hydrolysis and fermentation by S. cerevisiae 424A (LNH-ST). The identification of auxiliary enzyme activities, adequate process integration and the use of robust xylose-fermenting ethanologens were identified as opportunities to further improve ethanol yields from AFEX™- and StEx-treated sugarcane residues.en_ZA
dc.description.urihttps://biotechnologyforbiofuels.biomedcentral.com/articles/10.1186/s13068-018-1130-z
dc.description.versionPublisher's version
dc.format.extent21 pages : illustrationsen_ZA
dc.identifier.citationMokomele, T., et al. 2018. Ethanol production potential from AFEX™ and steam-exploded sugarcane residues for sugarcane biorefineries. Biotechnology for Biofuels, 11:127, doi:10.1186/s13068-018-1130-z
dc.identifier.issn1754-6834 (online)
dc.identifier.otherdoi:10.1186/s13068-018-1130-z
dc.identifier.urihttp://hdl.handle.net/10019.1/103976
dc.language.isoen_ZAen_ZA
dc.publisherBioMed Centralen_ZA
dc.rights.holderAuthor retains copyrighten_ZA
dc.subjectBagasseen_ZA
dc.subjectEthanol fuelen_ZA
dc.subjectBiofuelsen_ZA
dc.subjectSugarcaneen_ZA
dc.titleEthanol production potential from AFEX™ and steam-exploded sugarcane residues for sugarcane biorefineriesen_ZA
dc.typeArticleen_ZA
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