Abstract
BackgroundBioethanol 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).ResultsBoth 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%).ConclusionsMixing 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.
Highlights
Bioethanol can be produced from sugar-rich, starch-rich or lignocellulosic raw materials
The ethanol yields were calculated as a percentage of the maximal theoretical yield for glucose (0.51 g/g) that could have been produced if all the glucose present in the slurry and the presaccharified wheat meal (PWM), including both monomers and oligomers in the liquid and glucan fibres in the water-insoluble solids (WIS), had been converted to ethanol
Pretreatment is required to facilitate the enzymatic hydrolysis of starch-free residue (SFR) fibres, which was not performed in the present study
Summary
Bioethanol can be produced from sugar-rich, starch-rich (first generation; 1G) or lignocellulosic (second generation; 2G) raw materials. The capital cost per ton of fuel produced would be diminished and better utilization of the biomass can be achieved It would, decrease the energy demand of 2G ethanol production and provide both 1G and 2G plants with heat and electricity. Future expansion of biofuel production must be increasingly based on bioethanol from lignocellulosic materials, such as agricultural byproducts, forest residues, industrial waste streams or energy crops [7,8]. These feedstocks, which are being used in second-generation (2G) bioethanol production, are abundant, and their cost is lower than that of
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