Combined Process For Co-production Of Ethanol And Methane From Unwashed Steam-exploded Corn Stover

The successful development of a biofuel industry can reduce our reliance on fossil fuel, mitigate climate change, and help sustainable rural economic development in many countries. In china, corn stover is considered a promising biomass source for large-scale ethanol production because it represents a cheap, renewable, widely available feedstock. However, high solids processing for high-titer bioethanol production from lignocellulosic biomass to improve conversion efficiency and overall production yield, remains a challenge.A combined process was designed for co-production of ethanol and methane from unwashed steam-exploded corn stover. In the first bioethanol production process, we focused on achieving high ethanol yield from high solids substrate using fed-batch operation. As a result, a terminal ethanol titer of69.8g/kg mass weight, or72.5%theoretical, was achieved within72h when fed-batch mode was performed at a final solids loading of35.5%(w/w) dry matter content.Anaerobic digestion of fermentation stillage from pretreated lignolellulosic biomass material was investigated. As a result, the methane potential of whole stillage, liquid fraction and solids fraction was46,12,286mL CH4/g substrate respectively. These results indicate that high solids steam-exploded corn stover fermentation stillage has a great potential for methane production. The whole stillage from high solids ethanol fermentation was directly conducted anaerobic digestion by adapted anaerobic methanogens using3-L anaerobic digester. During52-day single stage digester operation, the methane productivity was320mL CH4/g VS with a maximum VS reduction efficiency of55.3%.The calculated overall product yield was197g ethanol+96g methane per kg corn stover. This indicated that the combined process was able to improve the utilization of overall contents, and extract9.6%more product yield of lignocellulosic biomass compared to ethanol fermentation alone.