(669b) Modeling for Identification of Operating Strategies for Continuous Simultaneous Saccharification and Fermentation (cSSF)

Although many economic studies assume continuous Simultaneous Saccharification and Fermentation (cSSF) will be the preferred configuration for commercial applications to achieve higher productivity and eliminate the need for seed fermentors, little information is available to guide process design or optimization. Therefore, in this paper, we focused on developing kinetic models to predict cSSF performance and applying them to better understand potential tradeoffs among enzyme loadings, residence times, yields, organism washout, and organism fermentation features to inform our new experimental research approach. Comparisons are made between batch and continuous processing to understand how end product inhibition and other characteristics differ and their effects on performance. In addition, simplified kinetic models are devised that require fewer measurable parameters to more easily predict the threshold for organism washout and how enzyme loadings impact system performance. Experimental results are compared to model predictions, and opportunities are identified for improving model accuracy. The result will be applied to identify optimal enzyme loadings and residence times for different pretreated feedstocks based on their compositions.