(355f) ABE (acetone, butanol, and ethanol) Production From Fiber-Enriched DDGS Pretreated by Electrolyzed Water

DDGS (distiller's dried grains with solubles) is the major co-product in dry grind ethanol production from corn. With the continuous expansion in corn ethanol production capacity, the proliferation of low value DDGS has become a problem impacting the overall economics of the dry grind ethanol facilities. The utilization of the carbohydrate components in DDGS for biofuel production will provide an option for diversifying the market and increasing the value of DDGS.

A physical process recently developed by Dr. Vijay Singh at University of Illinois at Urbana-Champaign (UIUC) separates DDGS into two value-added components: a fiber-rich portion and an enhanced DDGS which is rich in oil and protein. This work is undertaken to explore the use of the fiber-enriched portion for ABE production. Electrolyzed water, a new pretreatment catalyst first proposed and tested by Dr. Feng's group at UIUC was employed to pretreat fiber-enriched DDGS. The fermentability of the hydrolysates was examined with the hyper-butanol producing Clostridium beijerinckii BA 101 developed in Dr. Blaschek's laboratory.

To optimize the pretreatment conditions, four temperatures (130, 145, 160, and 175°C) and three treatment times (10, 20, and 30 min) were examined. The solids loading was set at 20% w/w by adding 8 g DDGS (dry weight) into tubular reactors to make a slurry that weighed 40 g. The enzymatic hydrolysis was performed in 100 mL VITLAB flasks in a shaker water bath at 50°C and 225 rpm with a solids loading of 10%. The enzyme loading was: 15 FPU cellulase/ g cellulose, 40 U β-glucosidase/ g cellulose, and 50 U xylanase/ g dry biomass. The hydrolysates were fermented by C. beijerinckii BA 101 at 35°C in an auto-controlled Six-fors fermentor with continuous mixing.

The highest sugar yield was achieved when using acid electrolyzed water treatment at 175°C and 10 min with 19.09 g glucose and xylose released from 100 g fiber-enriched DDGS. Other pretreatment methods, such as diluted sulfuric acid, alkaline solution, and hot water, were also performed. The resultant hydrolysates were successfully fermented consistent with the potential for using fiber-enriched DDGS co-product for the production of butanol. These findings bode well for the co-location of a corn based butanol and ethanol production facility.