Development of an electroactive aerobic biocathode for microbial fuel cell applications

Abstract

Summary Microbial biocathodes are gaining interest due to their low cost, environmental friendliness and sustainable nature. In this study, a microbial consortium was enriched from activated sludge obtained from a common textile effluent treatment plant in the absence of organic carbon source to produce an electroactive biofilm. Chronoamperometry method of enrichment was carried out for over 70 days to select for electroactive bacteria that could be used as a cathode catalyst in microbial fuel cells (MFC). The resultant biofilm produced an average peak current of −0.7 mA during the enrichment and produced a maximum power density of 64.6 ± 3.5 mW m−2 compared to platinum (72.7 ± 1.2 mW m−2) in a Shewanella‐based MFC. Microbial community analysis of the initial sludge sample and enriched samples, based on 16S rRNA gene sequencing, revealed the selection of chemolithotrophs with the most dominant phylum being Bacteroidetes, Proteobacteria, Firmicutes, Actinobacteria and Acidobacteria in the enriched samples. A variety of CO2 fixing and nitrate‐reducing bacteria was present in the resultant biofilm on the cathode. This study suggests that microbial consortia are capable of replacing expensive platinum as a cathode catalyst in MFCs.

Microbial fuel cell (MFC) performance with pigments bikaverin and congo red as electrochemical mediators for optmization power energy

“…When comparing the energy profiles of the electrochemical mediating pigments, a higher current density peak can be seen in Congo red, 273 mA.cm -2 in relation to bikaverin, 230 mA.cm -2 (Figure 4), with a coulombic efficiency of 71% and 43% respectively. In the literature, we found higher current density results than those found in this research, as the result of Mani, P., VT, F., et al (2020) which reached a maximum Id of 325 mA.cm -2 using a platinum catalyst on the cathode, which greatly increases the cost of a BC, but when using a bacterial consortium biocathode, it reached a maximum Id of 240 mA.cm -2 . However, a large amount of maintenance was required to try to maintain the stability of its system, which is a disadvantage compared to BC with bikaverin, which showed stability between 12 and 62 hours of experiment, totaling 50 hours.…”

Different autotrophic enrichments yield efficient inocula for biocathodic applications

“…Surprisingly, our results suggest that Methylomonas, UBA6140, and Nitrosomonas can uptake electrons from the cathode. While methane oxidizing taxa, Methylomonas and UBA6140 has not been reported as electro-active taxa before, Nitrosomonas was also detected as a dominant taxon in other biocathode studies (Du et al, 2014;Mani et al, 2020). Further studies are required to confirm and examine mechanism of EET of CH 4 and NH 3 oxidizers.…”

Magnetically Stimulated Bio‐ and Electrochemical Systems: State‐of‐the‐Art, Applications, and Future Directions

“…[154] However, in some particular cases, microbes and enzymes are also used as oxidant elements at the biocathodes. [155][156][157][158][159] The current concept of enzymatic bio-fuel cells (EBFCs) was first described by Yahiro and co-workers in 1964 when the enzyme GOx was used as a selective recognition element for bioanode operating in the presence of glucose. [160] Many subsequent advances were made such as implantable enzyme-based biofuel cells [161,162] and switchable/tunable EBFCs controlled by magnetic signals.…”