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Evaluating dilute phosphoric acid pretreated wheat bran for ethanol and edible fungal biomass production: A pilot study
University of Borås, Faculty of Textiles, Engineering and Business. Swedish Centre for Resource Recovery. (Biotechnology)ORCID iD: 0000-0001-5719-7252
University of Borås, Faculty of Textiles, Engineering and Business. Swedish Centre for Resource Recovery. (Biotechnology)
Swedish Centre for Resource Recovery. (Biotechnology)
University of Borås, Faculty of Textiles, Engineering and Business. (Resource Recovery)ORCID iD: 0000-0003-4887-2433
2015 (English)Conference paper, (Refereed)
Sustainable development
The content falls within the scope of Sustainable Development
Abstract [en]

Purpose of the work:

The present study reports the application of using dilute phosphoric acid for pretreatment of wheat branbiomass and its subsequent use as an ethanol fermentation substrate for edible fungi, Neurospora intermedia inbench scale (4.5L) and pilot airlift (26L) reactors.

Approach:

The optimized pretreatment conditions to release maximum sugar and minimum inhibitor concentrations weredetermined using a statistically modelled experimental setup. The dilute acid pretreatment was scaled up withthe validation of lab results in a biorefinery demo plant (BDP) at Svensk Etanolkemi AB – SEKAB (Örnsköldsvik,Sweden). The structural and physiological changes in the bran biomass during the pretreatment process werealso studied. Bench scale and pilot scale enzymatic hydrolysis of the pretreated biomass and subsequent ethanolfermentation using edible ascomycetes fungi, N. intermedia were studied using airlift reactors.

Scientific innovation and relevance:

With the use of dilute phosphoric acid, the study put forth an alternative strategy to the current use of relativelystronger acids for lignocellulosic biomass pretreatment. The potential use of acid pretreated lignocellulosicbiomass (wheat bran) as an ethanol feedstock, together with the edible fungal cultivation is a first of its kindapproach towards a wider ‘biorefinery’ concept. Improving the co-product (DDGS) quality and ethanol yield inthe existing wheat based ethanol facilities, whereby enhancing the overall ethanol production economics formsthe ultimate aim of the study.

Results:

Wheat bran was subjected to dilute acid pretreatment at varying acid concentrations (0.5–3.0% w/v),temperature (150–210◦C), and reaction time (5–20 min). The interaction of multiple factors showed theoptimum pretreatment conditions at acid concentration of 1.75% (w/v), at 190◦C for 10 min. A maximum totalpolysaccharide yield of 0.27 ± 0.01 g/g dry biomass loading, corresponding to 66% of the theoretical maximumwas observed. The effect of the dilute acid pretreatment on the functional groups of the wheat bran cellulosewas determined with 78% reduction in the cellulose crystallinity index. Enzymatic hydrolysis of pretreated slurryfrom the demo plant showed 85% total theoretical yield of polysaccharides. Compared to the untreated branbiomass, an increase of 51% was observed in the ethanol yield following pretreatment, with a total ethanol yieldof 95% theoretical maximum. Similar results were also observed on scaling up the reaction volume in a benchscale (4.5L) and pilot scale (26L) airlift reactors, which will also be presented in detail.

Conclusions:

The present work brings out the potential of using phosphoric acid as an efficient pretreatment agent addressingthe long existing problems associated with the sulfur contamination of the feed. Additional advantages relatedto the nutritional enrichment of DDGS (at the existing wheat based ethanol facility), with the use of edibleascomycetes fungi were also achieved. However, techno-economical analyses are required to determine theactual industrial feasibility of the process.

Place, publisher, year, edition, pages
2015.
Keyword [en]
Dilute phosphoric acid; Edible fungi; Ethanol fermentation; Neurospora intermedia; Pretreatment; Wheat bran; Pilot study
National Category
Engineering and Technology
Research subject
Resource Recovery
Identifiers
URN: urn:nbn:se:hb:diva-3328OAI: oai:DiVA.org:hb-3328DiVA: diva2:873748
Conference
IEA Bioenergy Conference 2015, Berlin, Germany
Funder
Swedish Energy Agency
Note

Purpose of the work:

The present study reports the application of using dilute phosphoric acid for pretreatment of wheat branbiomass and its subsequent use as an ethanol fermentation substrate for edible fungi, Neurospora intermedia inbench scale (4.5L) and pilot airlift (26L) reactors.

Approach:

The optimized pretreatment conditions to release maximum sugar and minimum inhibitor concentrations weredetermined using a statistically modelled experimental setup. The dilute acid pretreatment was scaled up withthe validation of lab results in a biorefinery demo plant (BDP) at Svensk Etanolkemi AB – SEKAB (Örnsköldsvik,Sweden). The structural and physiological changes in the bran biomass during the pretreatment process werealso studied. Bench scale and pilot scale enzymatic hydrolysis of the pretreated biomass and subsequent ethanolfermentation using edible ascomycetes fungi, N. intermedia were studied using airlift reactors.

Scientific innovation and relevance:

With the use of dilute phosphoric acid, the study put forth an alternative strategy to the current use of relativelystronger acids for lignocellulosic biomass pretreatment. The potential use of acid pretreated lignocellulosicbiomass (wheat bran) as an ethanol feedstock, together with the edible fungal cultivation is a first of its kindapproach towards a wider ‘biorefinery’ concept. Improving the co-product (DDGS) quality and ethanol yield inthe existing wheat based ethanol facilities, whereby enhancing the overall ethanol production economics formsthe ultimate aim of the study.

Results:

Wheat bran was subjected to dilute acid pretreatment at varying acid concentrations (0.5–3.0% w/v),temperature (150–210◦C), and reaction time (5–20 min). The interaction of multiple factors showed theoptimum pretreatment conditions at acid concentration of 1.75% (w/v), at 190◦C for 10 min. A maximum totalpolysaccharide yield of 0.27 ± 0.01 g/g dry biomass loading, corresponding to 66% of the theoretical maximumwas observed. The effect of the dilute acid pretreatment on the functional groups of the wheat bran cellulosewas determined with 78% reduction in the cellulose crystallinity index. Enzymatic hydrolysis of pretreated slurryfrom the demo plant showed 85% total theoretical yield of polysaccharides. Compared to the untreated branbiomass, an increase of 51% was observed in the ethanol yield following pretreatment, with a total ethanol yieldof 95% theoretical maximum. Similar results were also observed on scaling up the reaction volume in a benchscale (4.5L) and pilot scale (26L) airlift reactors, which will also be presented in detail.

Conclusions:

The present work brings out the potential of using phosphoric acid as an efficient pretreatment agent addressingthe long existing problems associated with the sulfur contamination of the feed. Additional advantages relatedto the nutritional enrichment of DDGS (at the existing wheat based ethanol facility), with the use of edibleascomycetes fungi were also achieved. However, techno-economical analyses are required to determine theactual industrial feasibility of the process.

Available from: 2015-11-24 Created: 2015-11-24 Last updated: 2016-01-19

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