title: Ethanol production from mixtures of wheat straw and wheat meal.
abstract: BACKGROUND
  Bioethanol can be produced from sugar-rich, starch-rich (first generation; 1G) or lignocellulosic (second generation; 2G) raw materials. Integration of 2G ethanol with 1G could facilitate the introduction of the 2G technology. The capital cost per ton of fuel produced would be diminished and better utilization of the biomass can be achieved. It would, furthermore, decrease the energy demand of 2G ethanol production and also provide both 1G and 2G plants with heat and electricity. In the current study, steam-pretreated wheat straw (SPWS) was mixed with presaccharified wheat meal (PWM) and converted to ethanol in simultaneous saccharification and fermentation (SSF).
  
  
  RESULTS
  Both the ethanol concentration and the ethanol yield increased with increasing amounts of PWM in mixtures with SPWS. The maximum ethanol yield (99% of the theoretical yield, based on the available C6 sugars) was obtained with a mixture of SPWS containing 2.5% water-insoluble solids (WIS) and PWM containing 2.5% WIS, resulting in an ethanol concentration of 56.5 g/L. This yield was higher than those obtained with SSF of either SPWS (68%) or PWM alone (91%).
  
  
  CONCLUSIONS
  Mixing wheat straw with wheat meal would be beneficial for both 1G and 2G ethanol production. However, increasing the proportion of WIS as wheat straw and the possibility of consuming the xylose fraction with a pentose-fermenting yeast should be further investigated.
authors.affiliation: Lund University, Department of Chemical Engineering, P,O, Box 124, SE-221 00 Lund, Sweden. Borbala.Erdei@chemeng.lth.se.
authors.forename: Borbála
authors.initials: B
authors.lastname: Erdei
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Barta
authors.forename: Bálint
authors.initials: B
authors.lastname: Sipos
authors.forename: Kati
authors.initials: K
authors.lastname: Réczey
authors.forename: Mats
authors.initials: M
authors.lastname: Galbe
authors.forename: Guido
authors.initials: G
authors.lastname: Zacchi