(328b) Development of In Situ Processes for Recovering Fatty Acid Biofuel Precursors From Photobioreactor

Cytotoxicity of biofuel production processes require continuous dilution of fermentation conditions which challenges the downstream separation and purification. Consumption by heterotrophic bacteria is also a limitation factor for the continuous growth and production of long-chain biofuel product, such as fatty acid (FA). An Expanded Bed Adsorption (EBA) harvest system has been set up for in situ recovery of fatty acid from genetically modified cyanobacteria culture, in which fatty acid was secreted and accumulated. Cell growth, fatty acid production, nutrient variability, and heterotrophic activity are all the potential issues which can be affected by the introduction of in situ harvest system. Then the integrated system with culture in flask and polymer resin in column (running as an EBA) was systematically studied. The FA can be harvested from the living cell culture in several hours by a continuous circulation between flask and EBA column, and FA product was eluted by special designed protocol. In addition to the product assays, nutrients were monitored along the growth and integrating harvest system, and its effect on cell growth and FA production were discussed in biological context. Sanitization conditions and heterotrophic growth are also key issues in the process integration. Then the heterotrophic contamination was monitored by Scan Electric Microscope (SEM). The competition between heterotrophic consumption and uptake to absorbent was compared by growth rate kinetic model  and adsorption kinetic model. The models were integrated together to predict some optimized operation strategy, which can suppress the heterotrophic growth and can be achieved by a Simulated Moving Bed (SMB) harvest mode.