Producing Hydrogen and Electricity From Wastewater in Biorefinery

Hydrogen is an important reagent in the thermochemical biorefinery for hydrotreatment and upgrading of bio-oil and other intermediates. Production of hydrogen from the waste streams generated during bioconversion and pyrolysis of biomass can not only improve the environmental sustainability of the process but also the economic feasibility if sufficient rate of hydrogen production can be obtained.

Bioelectrochemical systems (BES) are electrical devices that use energy in waste matter to generate usable energy or produce bioproducts using microorganisms as catalysts. Microbial fuel cells (MFCs) are one type of BES used to derive electricity from organic waste. In this work, MFCs were investigated for their ability to convert residual organics and pre-treatment byproducts to electricity. Wastewater obtained from a process for conversion of cellulosic biomass to biofuels was used. The treatment also removed  fermentation inhibitors such as furfural, HMF, phenolics and acetate from the wastewater, indicating potential to recycle water. Improvements in current density and coulombic efficiency of the bioanode were studied by varying multiple operational parameters. Water recycle and energy efficiency improvements are important issues for emerging cellulosic biomass fermentation industry. The unique exoelectrogenic microbial consortium enriched in the MFC has a broad substrate specificit with, ability to handle high inhibitor concentrations with near complete removal, while maintaining long-term stability. This approach can lead to: 1) higher ethanol yields at high biomass loading, 2) water recycle and 3) electricity or hydrogen production to improve energy recovery from biomass and potential for upgrading of low value fuels and bioproducts using hydrogen.