Sustainable production of value-added fuels and commodity products via microbial electrosynthesis

Forskningsprojekt, 2014 – 2015

The biorefinery concept, where energy and commodity chemicals are sustainably produced using alternative chemistry processes, has attracted a lot of attention from policy makers, research institutes and the industry. In the biorefinery, energy and chemicals are produced from biomass, instead of crude oil, and independence from fossil fuels is promoted. Fuels production from biomass has been expanding, however many of the biofuels, and especially first generation ones, are competing with food production because of their demands for land. A more sustainable option for the production of energy and chemicals is by utilising technologies that can convert waste and wastewater into “green” chemicals and energy, and this is what we propose in this research project.

Bioelectrochemical systems (BES) is considered a green-chemistry technology, where bacterial “catalysts” release the energy present in waste and wastewater and convert it into useful commodity products and fuels. When wastewater is the source of energy, water is being remediated in the anode and it can be safely returned to nature. Electrons released from wastewater are then transferred to the cathode, where microbes are generating electricity for the production of biogas and commodities which have a high energy and/or commercial value.

When working together with anaerobic digestion, BES cathodes can also be used as supporting processes for the treatment of troublesome wastewater streams and shock loads that can cause failure of the anaerobic digestion processes. Acidic wastewaters high in volatile fatty acids are such streams, which on one hand they can inhibit methane production but on the other hand they are good candidates for hydrogen production in BES. Hydrogen production increases the pH and improves hydrogenotrophic methanogenesis, which in turn produces biogas with a high methane content, even at ambient temperatures. Also, alcohols production (e.g. ethanol, propanol, butanol) from the chemical reduction of volatile fatty acids (e.g. acetate, propionate, butyrate) on the cathode is adding value to the final effluent and makes the process more economically attractive. Another way to add value to the final product is by co-digesting such wastewaters with wastewater coming from the biodiesel industry. Biodiesel production has been growing rapidly, producing increasing amounts of wastewater with a high glycerol content. When co-treated in a BES cathode, hydrogen and methane production can be enhanced and coupled with the conversion of the cheap glycerol to the very economically attractive commodity 1,3-propanediol (1,3-PDO).

In the proposed project we will study the sustainable production of biogas, alcohols and 1,3-propanediol, from wastewater treatment. Research work conducted by the applicant, also in support of this proposal (Appendix 1), confirmed that valuable commodities and fuels can be produced using BES technology, and that BES can improve methane production even under conditions which do not favour conventional anaerobic digestion. Such results have given us the tools to look deeper into optimizing the processes involved, and we can now exploit the BES capabilities even more. The work proposed will be conducted by Dr Nikolaos Xafenias, an Environmental Engineer with both PhD and post-doctoral research on water remediation and energy production using BES. The work will be done within the Industrial Biotechnology (IB) group of Chalmers University of Technology, which is supported by Chalmers’ Energy Area of Advance. The IB group is internationally recognized for its research on commodities production, it has a high interest in anaerobic digestion and other biorefinery processes, it is very well equipped for such a work, and therefore it is the most suitable host for the proposed project.