Monday, May 4, 2009
11-19
Biodiesel and H2 production from CO2 by sequential use of microorganisms in bioreactors
Sergei A. Markov, Dawn Danielson, Nimit Patel, Tracy Bisquera, Matt Murphy, Ryan Willingham, and Luke Holliday. Biology, Austin Peay State University, P.O.Box 4718, Clarksville, TN 37044
Photoconversion of light energy and waste CO2 into an array of biofuels by sequential use of microorganisms in bioreactors was studied. First the oil production by microalga Chlorella vulgaris was investigated in a batch culture and in a photobioreactor using waste CO2. Both flasks and a photobioreactor were illuminated with fluorescent light continuously. Algal biomass was recovered by centrifugation with subsequent drying under 80◦C. Algal oil was extracted with hexane. High oil content (50%) was found in Chlorella cells. Algal oil was converted into biodiesel by transesterification. A simple photobioreactor for biodiesel generation from microalgae was made from parallel clear PVC 10 feet tubes (6’ diameter) with a small slope (10%). The gas mixture (5% CO2 and air) flowed up from bottom of PVC tubes to the top as large gas bubbles. Next, glycerol, a by-product of biodiesel production, was used as a substrate for making biohydrogen (H2) by bacterium Enterobacter aerogenes in batch culture and in a bioreactor. Higher H2 production rates for up to 1600 mL g-1· DW· h-1 were observed than bacterial cells grew in the presence of 1% glycerol compared to 10% and 0.1% on a simple medium containing inorganic salts.