Monday, May 2, 2011
Grand Ballroom C-D, 2nd fl (Sheraton Seattle)
Coupling with wastewater treatment and biofuel production may offer an economically viable and environmentally friendly means for sustainable renewable energy among current existing processes. One of the key issues in above system is to select appropriate microalgae strains that could be tolerant of variety of wastewater resoources with high biomass and lipid productivity. In this study, bio-prospecting microalgal strains targeting local species of Minnesota, USA, was conducted with the aim to identify and characterize hyper-lipid producing facultative heterotrophic microalgal strains capable of surviving in organic-rich centrate, a highly concentrated municipal wastewater stream generated through dewatering of activated sludge, for biofuel production. Sixty-two algae like microorganisms were collected and isolated from different sampling sites of twin cities, Minnesota. After multi-step screening and acclimation process, twenty-nine facultative heterotrophic microalgal strains were obtained, among which twenty strains were proved to be tolerant in such concentrated municipal wastewater. These twenty top-performing strains were then identified as Chlorella sp., Scenedesmus sp., and Monoraphidium sp., respectively, based on morphological observation and DNA sequence analysis. Furthermore, the biomass productivity, fatty acid profile and fatty acid content of above twenty strains were systemically examined and one most promising strain, namely UM280, which adapt well in centrate wastewater environment with higher biomass and lipid productivity than other strains, was chosen for further evaluation in terms of the viability of scale-up and the stability of continuous operation in semi-continuous cultivation system using 25 L spiral tubing photo-bioreactor and 2000 L hybrid bioreactor under artificial light and natural sunlight conditions, respectively.