Simultaneous detoxification, saccharification, and ethanol fermentation of weak-acid hydrolyzates

Authors: Klasson, K Thomas; Dien, Bruce; Hector, Ronald - Ron

Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/30/2013
Publication Date: 8/1/2013
Publication URL: http://handle.nal.usda.gov/10113/62069
Citation: Klasson, K.T., Dien, B.S., Hector, R.E. 2013. Simultaneous detoxification, saccharification, and ethanol fermentation of weak-acid hydrolyzates. Industrial Crops and Products. 49:292-298.

Interpretive Summary: Biomass raw materials can be prepared for biofuel (alcohol) fermentation by pre-treatment with a weak acid that break up part of the biomass structure and open up the plant fibers for a second treatment with enzymes. However, the weak acid degrades sugars to other chemicals that are toxic to the microorganisms used in the fermentation. This work evaluated the use of agricultural waste (flax shive) as starting material for making activated biochar to capture these toxic degradation products. Results show that both furfural and hydroxymethylfurfural (HMF) are captured by steam-activated biochar prepared from flax shive. Cleaning of the hydrolyzate significantly improved the fermentation behavior by yeast, including significantly reducing the start-up period of the fermentation. No negative effects were noted from addition of activated char to the process.

Technical Abstract: Lignocellulosic feedstocks can be prepared for ethanol fermentation by pre-treatment with a dilute mineral acid catalyst that hydrolyzes the hemicellulose and opens up the plant cell wall fibers for subsequent enzymatic saccharification. The acid catalyzed reaction scheme is sequential whereby released monosaccharides are further degraded to furans and other chemicals that are inhibitory to the next fermentation step. This work evaluated the use of agricultural residue (flax shive) as starting material for making activated biochar to adsorb these degradation products. Results show that both furfural and hydroxymethylfurfural (HMF) are adsorbed by steam-activated biochar prepared from flax shive. Decontamination of the hydrolyzate significantly improved the fermentation behavior by Saccharomyces cerevisiae yeast, including significantly reducing the lag phase of the fermentation, when the amount of biochar added to the fermentation broth was 2.5% (w/v). No negative effects were noted from addition of activated char to the process.