Electron donor availability controls scale up of anodic biofilms

By Tutar, Secil; Mohamed, Abdelrhman; Ha, Phuc T.; Beyenal, Haluk
Published in Bioelectrochemistry 2019

Abstract

The scale-up of bioelectrochemical systems (BESs) is a challenging problem that limits the advancement and practical implementation of the coupled technology. The goal of this work is to acquire an understanding of the limitations on scaling up anodic biofilms in BESs. We hypothesized that scaling up is dependent on the availability of electron donors. We tested this hypothesis by enriching anodic biofilms on electrodes of multiple sizes (15 cm2 to 466 cm2) and quantified the anodic current densities while varying the electron donor concentrations. The anodic biofilms were enriched on electrodes under two conditions: 1) in raw wastewater and 2) in wastewater supplemented with 20 mM acetate. Following anodic biofilm enrichment, the current density for each electrode was quantified in artificial wastewater medium with variable COD loadings using acetate as an electron donor. Current generated using anodic biofilms scaled up at a high COD loading (1500 mg/L), while current density decreased with increasing electrode size at lower COD loadings. Further, microbial community analysis revealed that the microbial community was independent of the electrode size but dependent on the medium composition during the enrichment phase. These results provide a practical framework for the design of large-scale BESs based on laboratory-scale measurements.

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