Performance of a cell recycling continuous fermentation system for the production of n-butanol by Clostridium acetobutylicum

In order to enhance the economics of n-butanol production, this study evaluates continuous butanol fermentation in a stirred tank reactor (CSTR). Culture viability is maintained by reinoculating heat shocked cells harvested from the fermenter effluent. Accurate evaluation requires closed material and oxidation-reduction balances. These preliminary experiments indicate that increased butanol production occurs in a continuous stirred tank reactor when cell recycle is used. The amount of increased butanol production for an unbalanced, non-optimized media was ca. 3. 5 in these experiments. We anticipate a further increase in butanol production with optimized media, better pH control, and continuous cell mass recycling.