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Design of 3D microbial anodes for microbial electrolysis cells (MEC) fuelled by domestic wastewater. Part I: Multiphysics modelling

Lacroix, Rémy and Roubaud, Emma and Erable, Benjamin and Etcheverry, Luc and Bergel, Alain and Basséguy, Régine and Da Silva, Serge Design of 3D microbial anodes for microbial electrolysis cells (MEC) fuelled by domestic wastewater. Part I: Multiphysics modelling. (2021) Journal of Environmental Chemical Engineering, 9 (4). 105476. ISSN 2213-3437

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Official URL: https://doi.org/10.1016/j.jece.2021.105476

Abstract

The performance of a microbial electrolysis cell (MEC) supplied with domestic wastewater (dWW) is essentially limited by the kinetics of the anodic bioelectrochemical reactions and the low ionic conductivity of the electrolyte. A strategy to boost-up the anodic bioelectrochemical kinetics is to use three-dimensional (3D) microbial anodes that offer a high total anodic surface area and volume density of electroactive biofilm. In this work, a 3D multiphysics model was designed to simulate the current generation and resulting hydrogen production in double and triple-compartment MECs fed continuously with dWW. Simulations indicated that optimised 3D microbial anode geometries could simultaneously increase current and chemical oxygen demand (COD) removal by 86% compared to a 2D planar graphite electrode. At a constant CEM voltage, the current produced increased with the thickness of the 3D microbial anode up to a limiting thickness of 20 mm. Beyond this value, the current was stagnant due to the predominant ohmic drop. Current generation and COD removal could be further increased by designing 3D anode geometrical arrangements that force the dWWs to flow through the porosity of the 3D microbial anode. A gain of 20% was calculated by substituting a monolithic 3D graphite anode with a 3D anode of the same thickness (20 mm) but constructed of plates stacked on top of each other and spaced 2.5 mm apart. Finally, hydrogen production performance was additionally optimised by a further + 20% by switching from a two-compartment MEC design (anode-cathode) to a three-compartment MEC design (cathode-anode-cathode).

Item Type:Article
HAL Id:hal-03253390
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:Other partners > 6T-MIC Ingenieries (FRANCE)
Other partners > 6T-MIC Ingenieries (FRANCE)

French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UT3 (FRANCE)
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Funders:
Agence Nationale de la Recherche (France)
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Deposited On:08 Jun 2021 09:44

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