Reverse Osmosis for the Concentration of Organic Solvents from Acetone-Butanol Fermentation Broth

Abstract

Reverse osmosis (RO) for  the separation of organic solvents (butanol, ethanol, acetone, butyric acid and acetic acid) from fermentation broth has been studied. The broth was prepared from acetone-butanol-ethanol fermentation by Clostridium acetobutylicum ATCC 824 using enzyme hydrolysate of tapioca as a raw material. Polymide had been used as the membraste for the separation. The effect of operating pressure, circulation flow rate and concentration of organic solvents on the properties of the reverse osmosis system has been investigated. The optimal applied pressure and circulation flow rate for the separation was 40-50 kg/hr and 3-5 L/min respectively with permeate flux more than 20 L/m²hr, 93-98% rejection and 99.5-99.9% recovery. Experimental results showed the energy supply to concentrate 9.5 g/L butanol in fermentation broth to 19.1 g/L by the reverse osmosis process were about 1/10 of that by batch distillation process.