With global energy consumption consistently on the rise, there is a need to match supply to demand using alternative energy sources. Current energy sources rely heavily on fossil fuels; however, their emissions have been implicated in environmental and health issues. National and global policies have been implemented in an effort to reduce fossil fuel emissions and promote alternative energy sources. One of the more well-known alternative energy sources is biodiesel. Biodiesel is typically manufactured from seed oils or from waste vegetable oil by base-promoted transesterification using methanol or ethanol. Production of biodiesel is accompanied by 10% of glycerol by-product. With increasing production of biodiesel, the industrial market for crude glycerol has all but evaporated. Costs associated with crude glycerol disposal contribute to an increased cost to the consumer adversely affecting the market competitiveness of biodiesel with fossil fuels. To decrease crude glycerol disposal costs, current research has focused on finding new uses for crude glycerol including conversion to value-added products. In our work, we have used Enterobacter aerogenes, a facultative, anaerobic bacterium that is known to ferment crude glycerol yielding ethanol as one of its metabolic products. Ethanol produced in this way can be used directly as an alternative energy source, blended into fossil fuels, or put back into the biodiesel production process replacing or supplementing the methanol in the transesterification, thus lowering the cost of biodiesel in the energy marketplace. In our work, we use a chemostat to induce selective pressure on the growth and reproduction of E. aerogenes in a diluted glycerol/nutrient mixture. We present NIR results that show feasibility of conversion of glycerol to ethanol using E. aerogenes and have determined an optimal collection time from the chemostat for maximum ethanol production.

Increasing efficiency of ethanol production from crude glycerol and Enterobacter aerogenes

255th National Meeting (2018)

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