Por:
Ana María Valencia López
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Fecha:
2011
The Microbial Fuel Cells allow the direct conversion of chemical energy, contained in different substrates, into electric energy. A typical MFC consists of two compartments, anode and cathode separated by a Proton Exchange Membrane (PEM). In the anodic compartment the oxidation of the organic waste takes place, while the electron acceptor is reduced in the cathodic compartment. Forcing the electrons passage through an external circuit and thanks to the protons transport between both compartments, it is ensured the maintenance of the charge balance inside and the electric circuit is closed.
The main purpose of this study has been to evaluate the performance, in terms of the power (P; mW/L, mW/ m2) and the Open Circuit Voltage (OCV;V), of a laboratory scale MFC to vary the microorganisms type which have the task of extracting the electrons from the substrate and carry them to the anode. In addition, the effects of the use of a redox mediator have been evaluated, which would allow a reduction on the anode overpotential. It was finally carried out the cell scale-up with the goal of identifying the parameters that mostly influence the performance of the system.The microorganisms used as biocatalysts in this study have been divided in three groups:
- Brewer’s yeast, Saccharomyce cerevisiae
- Acetogenic bacteria pretreated at pH 3
- Microorganisms present in seawater
With the brewer’s yeast, the effect of varying its concentration on the MFC performance has been studied, noting that, with the growth of this parameter, the power density of the cell increases. In these tests it was used the methylene blue as an electronic carrier and has been verified that when the carrier/microorganism ratio is lower, the performance is better. Regard to the microorganisms in seawater, some tests have been carried out to determine the influence on the MFC performance of several factors, such as; the storage of the samples at low temperature (test A2 and A4), the change of the inoculum concentration on the anode chamber (test A3), the use of inoculums enriched through successive growths (Test A7 and A8), the absence of electronic carrier on the electron transport to the anode and, as a consequence, on the power density obtained (Test A5, A6, A7 and A8). Finally it has been analyzed the effect of the scale-up and the recirculation conditions of the electrolyte solutions on the MFC performance (Test A9).
Fuente:
Biblioteca Virtual Banco de la República
Formatos de contenido:
Tesis
