Biofilm and planktonic population distribution. Key aspects in carbonaceous anodes for microbial fuel cells

Abstract

BACKGROUND A comparison between different carbon-based anodes used in microbial fuel cells (MFCs) has been carried out. Five different carbonaceous anodes were studied: carbon paper, carbon cloth, carbon foam 30 ppi, carbon foam 80 ppi and carbon felt.

RESULTS The current density generated was higher for the MFCs with porous anodes compared with the flat ones, generating up to 14.5 A m−2. However, when the superficial surface was higher than 7500 m2 m−2 the performance did not increase further due to microorganisms transport and mass transfer limitations. Regarding the biochemical performance, a linear relationship between the generated current density and the coulombic efficiency was found. This relationship indicates selection of the electrogenic microbial population when the superficial surface increases. From Illumina MiSeq analyses, it was observed that Shewanella population in the biofilm was c. 14%, while its population was negligible in the planktonic culture. This population distribution can be explained by the low growth rate of the Shewanella.

CONCLUSIONS These results demonstrate that the main driving force of the carbonaceous materials performance is the ease of biofilm formation and subsequent population selection, but not on specific electronic properties of the carbon materials. © 2018 Society of Chemical Industry