Search

In this study, bacteria from a microbial fuel cell (MFC) and isolates were evaluated on their Fe

An iron reducing enrichment was obtained from sulfate reducing sludge and was evaluated on the capability of reducing Fe3+ coupled to acetate oxidation in a microbial fuel cell (MFC). Three molar ratios for acetate/Fe3+ were evaluated (2/16, 3.4/27 and 6.9/55 mM). The percentages of Fe3+ reduction were in a range of 80–90, 60–70 and 40–50% for the MFCs at closed circuit for the molar ratios of 2/16, 3.4/27 and 6.9/55 mM, respectively. Acetate consumption was in a range of 80–90% in all cases. The results obtained at closed circuit for current density were: 11.37 mA/m2, 4.5 mA/m2 and 7.37 mA/m2 for the molar ratios of 2/16, 3.4/27 and 6.9/55 mM, respectively. Some microorganisms that were isolated and identified in the MFCs were Azospira oryzae, Cupriavidus metallidurans CH34, Enterobacter bugandensis 247BMC, Citrobacter freundii ATCC8090 and Citrobacter murliniae CDC2970-59, these bacteria have been reported as exoelectrogens in MFC and in MFC involving metals removal but not all of them have been reported to utilize acetate as preferred substrate. The results demonstrate that the isolates can utilize acetate as the sole source of carbon and suggest that Fe3+ reduction was carried out by a combination of different mechanisms (direct contact and redox mediators) utilized by the bacteria identified in the MFC. Storage of the energy generated from the 2/16 mM MFC system arranged in a series of three demonstrated that it is possible to utilize the energy to charge a battery.

An iron reducing enrichment was obtained from sulfate reducing sludge and was evaluated on the capability of reducing Fe

Some microorganisms (such as bacteria) are capable of producing renewable energy without harassing the environment. Microbial fuel cells (MFC) offer thepossibility of transforming organic matter into electricity by using the metabolism of these microorganisms, creating ions within the subproducts of the metabolism that go to the extracellular environment. An electrode is set into the MFC that works as a final acceptor that attracts the electrons released by the microorganisms after consuming organic matter. To date, many microorganisms with the capability of liberating electrons through their metabolism have been identified. However only few are able of doing so without chemical mediators, which is why the search of new exoelectrogen microorganisms is of great importance. On the present work, two different MFC were employed for optimizing the isolation of exoelectrogenic bacteria gathered from mud of the Lerma river and from the Centro Interamericano de Recursos del Agua water treatment plant. Voltage generated by these microorganisms was compared with that created by Geobacter sulfurrenducens , one of the most efficient bacteria in this field. Overall, the obtained data show that the isolated bacteria at the National Institute of Nuclear Research facilities (identified by ribosomal RNA as Clostridium sordellii and C. bifermentans ) have a good voltage generation, although not as good as the one from G. sulfurrenducens . Results indicate that the strategy employed in the research is suitable for efficiently locating, isolating and identifying exoelectrogenic bacteria that may be used later on for the in situ generation of electricity in polluted areas.