(782f) Volatile Fatty Acids As a Sole Carbon Source for Biocrude Production by Enhanced Activated Sludge Cultures

A study on the use of short-chain volatile fatty acids (VFA) as substrates for biofuel feedstock lipids (biocrude) production in enhanced activated sludge cultures will be presented. As part of the overall goal of establishing a sustainable wastewater treatment plant – based biorefinery, it is suggested to treat waste lignocellulose biomass by anaerobic digestion to yield volatile fatty acids such as acetate, butyrate, and propionate; after which the said VFAs will be fed into activated sludge cultures to produce biocrude via fermentation. In this study, batch fermentation experiments using individual VFAs and synthetic ternary mixtures of acetate, propionate, and butyrate with varying ratios as substrates will be conducted in flask cultures and 3-L bench-scale bioreactors. Samples will be analyzed for biomass and lipid yields, residual VFAs in the fermentation broth, and fatty acid profile of the biocrude product. Kinetic analysis of the fermentation data will be conducted to evaluate the growth and lipid production performance of the activated sludge microorganisms using VFAs as the carbon source. This approach could potentially be a more cost-effective alternative to using sugars obtained by acid hydrolysis of biomass since anaerobic digestion is commonly a built-in component within the wastewater treatment process. VFAs fermentation could also provide a relatively higher carbon yield than direct sugar fermentation due to their relatively easier assimilation into the biochemical pathways leading to lipid biosynthesis in microorganisms than sugars.