Theses and Dissertations at Montana State University (MSU)
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/733
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Item A microbial fuel cell using biomineralized manganese oxides as a cathodic reactant(Montana State University - Bozeman, College of Engineering, 2005) Rhoads, Allison Nicole; Chairperson, Graduate Committee: Zbigniew LewandowskiMicrobial fuel cells were designed and operated utilizing microorganisms in both the anodic and cathodic compartments. In the cathodic compartment we used Leptothrix discophora because of the microorganism's capability to deposit biomineralized manganese oxides on the electrode. Biomineralized manganese oxides are superior to oxygen when used as a cathodic reactant. In the anodic compartment of most of the fuel cells we oxidized glucose using Klebsiella pneumoniae. In one fuel cell we used Desulfovibrio desulfuricans, a sulfate reducing bacteria. Electrons released in the anodic compartment, from the oxidation of glucose or sulfide, were then used in the cathodic compartment to reduce microbially deposited manganese oxides. A redox mediator, 2-hydroxy- 1,4-napthoquinone (HNQ) was used in the anodic compartment to facilitate electron transfer from the microorganism to the electrode. The fuel cells with glucose oxidizing bacteria were operated for 500 hours and reached an average anodic potential of -441±31 mVSCE and an average cathodic potential of +384±62mVSCE. The fuel cells with sulfate reducing bacteria were operated for 136 hours and reached an average anodic potential of -470±44 mVSCE and an average cathodic potential of +419±59 mVSCE. Reticulated vitreous carbon or 316L stainless steel was used as the electrode material. The electrode materials did not have a significant effect on the potential of the fuel cell system. The average fuel cell potential for 316L stainless steel was 706.13±22mV and 759.75±73mV for reticulated vitreous carbon. When the fuel cells reached steady state we discharged them through a 510. resistor and evaluated the available power.Item Power management for microbial fuel cells(Montana State University - Bozeman, College of Engineering, 2005) Shantaram, Avinash; Chairperson, Graduate Committee: Z. LewandowskiMonitoring parameters characterizing water quality, such as temperature, pH and concentrations of heavy metals in natural waters, is often followed by transmitting the data to remote receivers using telemetry systems. Such systems are commonly powered by batteries, which can be inconvenient at times because batteries have a limited lifetime and have to be recharged or replaced periodically to ensure that sufficient energy is available to power the electronics. To avoid these inconveniences, we have designed and tested a self-renewable power source, a microbial fuel cell, which has the potential to eliminate the need for batteries to power electrochemical sensors used to monitor water quality and small telemetry systems used to transmit the data acquired by these sensors. To demonstrate the utility of the microbial fuel cell, we have combined it with low-power, high-efficiency electronic circuitry providing a stable power source for wireless data transmission. To generate enough power for the telemetry system, energy produced by the microbial fuel cell was stored in an ultracapacitor and used in short bursts when needed. Since powering commercial components of electronic circuits requires 5 Volts, and our cell was able to deliver a maximum of 2.1 V, we used a DC-DC converter to increase the potential. The DC-DC converter powered the transmitter, which gathered the data from the sensor and transmitted them to a receiver. To demonstrate the utility of the system, we initially measured temporal variations in temperature followed by the implementation of a chemical sensor to measure copper and lead concentrations in water; this data was then wirelessly transmitted to a remote receiver.