Acetone butanol ethanol (ABE) recovery by pervaporation using silicalite–silicone composite membrane from fed-batch reactor of Clostridium acetobutylicum

Acetone butanol ethanol (ABE) were produced in an integrated fermentation-product recovery system using Clostridium acetobutylicum ( C. acetobutylicum) and a silicalite–silicone composite membrane. Cells of C. acetobutylicum were removed from the cell culture using a 500,000 molecular weight cut-off ultrafiltration membrane and returned to the fed-batch fermentor. The ABE was removed from the ultrafiltration permeate using a silicalite–silicone composite pervaporation membrane. The silicalite–silicone composite membrane (306 μm thick) was made in our laboratory and characterized for flux and selectivities using model acetone ethanol butanol solution. Flux of the silicalite–silicone composite membrane was constant during pervaporation of fermentation broth at the same concentration of ABE. Acetone butanol selectivity was also not affected by the fermentation broth, indicating that the membrane was not fouled by the ABE fermentation broth. The silicalite–silicone composite membrane was exposed to fermentation broth for 120 h. Acetic acid and ethanol did not diffuse through the silicalite–silicone composite membrane at low concentrations. The fed-batch reactor was operated for 870 h. Totally 154.97 g/l solvents was produced at solvent yield of 0.31–0.35.