Structure function relationship of electroactive biofilms in microbial fuel and electrolysis cells
Final Report Abstract
In bioelectrochemical systems (BES), the formation and architecture of biofilms are of particular significance, especially in the context of flow-through applications. The interaction between electroactive microorganisms and the electrode surface is of great importance, yet frequently a limiting factor. The available surface area has a direct impact on current generation, particularly for organisms that form weak biofilms. To address the limitations of restricted electrode surface area, nanoparticles (NPs) comprising a magnetic iron core and a conductive, hydrophobic carbon shell were employed as building blocks to create conductive, magnetic micropillars on the anode. The dynamic, three-dimensional electrode structure was monitored and quantified in situ using optical coherence tomography (OCT) integrated with microfluidic BES systems. Cyclic voltammetry demonstrated that the assembled anode extensions were indeed electrically conductive, thereby effectively expanding the electroactive surface area. Furthermore, the NPs served as controllable carriers for electroactive model organisms, namely Shewanella oneidensis and Geobacter sulfurreducens. This resulted in a fivefold increase in steady-state current density for S. oneidensis. This enhancement reached a maximum of 22-fold when combined with poly(3,4-ethylenedioxythiophene)- poly(styrenesulfonate) (PEDOT:PSS) aggregates. In contrast, while the steady-state current density for G. sulfurreducens did not increase, it was achieved four times faster. This study demonstrates a controllable, scalable, and straightforward approach to enhance electrode surface area in existing BES through the application of a magnetic field and conductive magnetic NPs. It is probable that these results can be transferred to other electroactive microorganisms, potentially broadening the applicability of this method in BES optimization.
Publications
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Elucidating the development of cooperative anode-biofilm-structures. Biofilm, 7, 100193.
Klein, Edina; Wurst, René; Rehnlund, David & Gescher, Johannes
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Magnetic, conductive nanoparticles as building blocks for steerable micropillar-structured anodic biofilms. Biofilm, 8, 100226.
Wurst, René; Klein, Edina & Gescher, Johannes
