CHALLENGES AND POSSIBILITIES OF SECOND GENERATION BIOETHANOL PRODUCTION PROCESS AT HIGH SUBSTRATE
Conference poster, 2012
In the scientific battle of alleviating green house gas emissions, second generation bioethanol produced from cheap, renewable and abundantly available lignocellulosic materials, is believed to play a major role. However, the commercialization of cellulose-to-ethanol remains challenging due to various limitations in process technology and microbial physiology. An important process parameter is the ability to work under high-solids concentration for the energy balance and economical viability of bioethanol production. Maintaining high substrate concentration presumed to result in high sugar yield and high ethanol concentration in subsequent yeast based fermentation. Practical limitations to a high-solids process include, poor mixing and accessibility of enzymes to substrates and high inhibitors concentration that reduces the yeast viability and metabolism. The current work involves testing various feeding strategies with enzymes and substrates yeast in a simultaneous saccharification and fermentation (SSF) process in contrast to a conventional batch SSF process. The aim is to understand how different combination of feeding strategies that influence the outcome of the SSF process. In the longer perspective, we aim at deducing an optimized SSF process that can handle very high-solids concentration with efficient hydrolysis and fermentation process at low enzyme and yeast loadings, respectively.