Characterization and optimization of anodes for microbial electrochemical technologies treating wastewater Abstract: Microbial electrochemical technologies (METs) can produce power from renewable sources or produce platform chemicals from carbon dioxide. They are developed within a highly multi disciplinary and dynamic research environment with the aim to contribute to the global energy transition towards sustainable and renewable energy production energy efficient remediation and bioproduction processes. This work has carried the development of METs significantly forward on three different levels. <br>(1) Engineering: Existing reactor designs are analyzed in detail and rated. Furthermore a new reactor concept for the integration of METs into wastewater treatment is presented and characterized. (2) On the biological level different inoculation strategies for the improvement of anode performance are described and (3) On the methodological level (bio )electrochemical methods to characterize and evaluate METs are revised.<br>1.The highlight of this work is the development of a new reactor concept (Chapter 5) based on the findings of the analysis and rating of existing reactor designs (Chapter 2.4). The new reactor concept aims at the production of electricity for reducing the overall energy consumption of wastewater treatment and is realized as a combination of METs and membrane bioreactors. It was granted with a German and European patent and the novelty of this development is an anode which is simultaneously used as microfiltration membrane in sidestream crossflow configuration. To evaluate the feasibility of such an anode the concept is proved using sintered porous stainless steel with G. sulfurreducens and an acetate based synthetic medium. Resulting current densities were increased up to 4 fold compared to a standard bioelectrochemical anode setup. E.g. a stainless steel filter of the grade 0.5 µm solely used as anode achieves current densities of 4 A m−2 in a standard setup and > 15 A m−2 when it is simultaneously used as filtration element in crossflow configuration. To test the feasibility of this new reactor treating wastewater it is subsequently operated as anaerobic membrane reactor (AnMBR) and the degradation of chemical oxygen demand (COD) monitored. These experiments show that significant conversion of COD to electrical current on the filter used as anode takes place. The COD removal achieves up to 450 mg L 1 showing great potential for increasing treatment efficiencies and having a polishing effect on the effluent from an AnMBR.<br>2.An ...