(718f) The Sustainable Conversion of Algal Sugars Into Butanol

Algae is an attractive feedstock since it can grow on marginal land, has a very high growth rate, and takes up nutrients as it grows so it has the potential to clean wastewater while making fuel feedstock. However, although much research is taking place on converting the algal lipids to biodiesel, there are few studies on converting algal carbohydrates to alcohols. The algal carbohydrates are mainly starches and simple sugars so they are much easier to pretreat and ferment than cellulosic sugars. Our group is working on taking a two step butanol process and continually converting algal sugars into butanol. The first step does an acidgenesis, with Clostridium Tyrobutyricum, for the conversion of sugars to organic acids, specifically butyric acid. The second step takes the butyric acid and converts it into butanol via Clostridium Beijerinckii. Although this is an anaerobic fermentation, we have used membrane processes to make both steps in the two-step process continuous and have modeled the reaction steps in the first and the second step. The yield of this process can go from 6:3:1 butanol, acetone, and ethanol, respecitively to greater than 90% butanol by optimizing both steps.