A scalable, Rotating Disc Bioelectrochemical Reactor (RDBER) suitable for the cultivation of both cathodic and anodic biofilms

Abstract

AbstractThis study discusses the construction and operation of a membrane-less bioelectrochemical reactor that employs rotating working electrodes with a surface area of up to 1 m2. As a proof-of-principle for an aerobic microbial electrosynthesis process,Kyrpidia spormanniiwas cultivated in the reactor. Optical coherence tomography was used to examine the spatial distribution of the cathodic biofilm. After 24 days 87% of the cathode surface was covered with biofilm that was characterized by a radial increase in its biovolume towards the circumcenter of the electrodes reaching up to 92.13 μm3μm-2. To demonstrate the versatility of the system, we further operated the reactor as a microbial electrolysis cell employing a co-culture ofShewanella oneidensisandGeobacter sulfurreducens. Anodic current densities of up to 130 μA cm-2were measured during these batch experiments. This resulted in a maximum production rate of 0.43 liters of pure hydrogen per liter reactor volume and day.Graphical AbstractHighlightsConstruction of a 10 L membrane-less, pressurizable bioelectrochemical reactorRotating working electrodes with up to 1 m2electrode surfaceElectroautotrophic cultivation and quantification ofK. spormanniibiofilmsInitial cell density crucial for successfulK. spormanniibiofilm formationAnodic operation as MEC withShewanella/Geobactercoculture