Butanol fermentation by fibrous bed bioreactor integrated with gas stripping

Acetone-butanol-ethanol (ABE) fermentation with Clostridium acetobutylicum CGMCC 5234 immobilized in fibrous bed bioreator was studied for its potential utilization to produce ABE that can be easily recovered by gas stripping with gas products CO₂ and H₂. The process was conducted in fed-batch fermentation for twelve feeding cycles over 309 h, and 133.3 g·L^-1 ABE(83.5 g·L^-1 butanol, 38.4 g·L^-1 acetone, 11.4 g·L^-1 ethanol) was produced. The overall productivity and yield were 0.431 g·(L·h)^-1 and 0.333 g·g^-1 for ABE and 0.270 g·(L·h)^-1 and 0.209 g·g^-1 for butanol. The concentration of butanol in the fermentation liquid was 8-12 g·L^-1. Phase separation of condensed ABE after gas stripping with up to 603.7 g·L^-1 butanol in the butanol phase would relieve the burden of subsequent separation and purification. The results showed that the fed-batch fermentation with intermittent gas stripping was feasible and competitive.