Background: Electrobiotechnology combines the use of renewable electrical energy and bio-based resources, as well as CO2, for the sustainable synthesis of chemicals and fuels ("power-to-chemicals"). Advantages of this process over conventional (electrochemical) syntheses include potentially higher selectivities and yields. Challenge: Current reactor systems for bioelectrochemical syntheses are small-scale, home-built systems with minimal process control, making syntheses incomparable and preventing systematic process development toward commercially viable syntheses. To close the gap between research and application, standardization of microbial electrosyntheses and their comparability with conventional biosyntheses are essential. Innovation: This upgrade kit expands conventional bioreactors for use in microbial electrosynthesis. An open reaction chamber with an ion-selective membrane is placed inside the bioreactor and attached to the reactor lid. In addition to the usual connections for stirrers, measuring probes, aeration and degassing, etc., the lid contains additional openings for electrodes, each extending into the inner and outer reaction chambers, respectively, making the system suitable for bioelectrosynthesis. The upgrade kit also provides a basis for the development of a standardized electrobioreactor up to an industrial scale.

High energetic potential in wastewater • Currently, wastewater treatment in industrialized countries is an energy-intensive process. It is estimated that 20% of municipal electricity consumption in Germany is used for wastewater treatment (K. Fricke, Energy Efficiency of Municipal Wastewater Treatment Plants, Federal Environment Agency, Dessau-Roßlau, 2009). • At the same time, wastewater has a considerable energy content • Example calculation: sewage treatment plant size 4, 55000 PE (2.5 million m3 wastewater annually), if only domestic wastewater is used, 450 MWh per year would be possible (at only 10% efficiency) The UFZ approach - bioelectrochemistry