Date of Award

2006

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Master of Science in Civil Engineering (MSCE)

Department

Civil Engineering

Advisor

Jean MacRae

Second Committee Member

Aria Amirbahman

Third Committee Member

Nick P. Brown

Abstract

Abstract

Organic pollution of marine and freshwater environments has long been a problem due to spills, shipping or boating activity, runoff, and waste discharge. Microbial Fuel Cells (MFC) harness electrons released during the oxidation of organic carbon to produce an electric current. Hydrocarbons are normally broken down into carbon dioxide and water by microbial respiration, where electrons from hydrocarbons are transferred to an electron acceptor such as oxygen. In sediment, however, oxygen is consumed within the top few centimeters, and other electron acceptors such as sulfate yield less energy, which slows the degradation process. A MFC anode placed in the anaerobic sediment transports the electrons to oxygen in the overlying water, allowing hydrocarbon degradation to proceed. Aquaculture releases high levels of nitrogen to the environment. Excess nitrogen concentrations lead to algal blooms, depleted oxygen levels and massive fish kills. Replacing oxygen with nitrate as the terminal electron acceptor in the cathode reaction of a MFC could remove nitrogen from aquaculture effluent streams. Over the past twelve months, research was conducted to determine the feasibility of utilizing MFCs to accelerate the degradation diesel fuel in marine sediment as well as nitrate removal from aquaculture effluent. Batch reactor MFCs were designed to assess the hydrocarbon degradation rates of artificially contaminated sediment under various conditions. These reactors were also used to determine if nitrate could be removed at the cathode using a MFC powered by fish biosolids. After 117 days of operation, the diesel fuel concentrations in the MFCs were equal to controls signifying that the MFC did not accelerate degradation of the hydrocarbons. The MFCs did produce a measurable power output. After approximately 100 days contaminated sediment reactors produced the same power output as uncontaminated reactors. The results signify that contaminated sediments can be used for power production but fuel cells do not contribute to accelerated bioremediation in short time frames. Power was produced using fish biosolids combined with oxygen in a MFC reactor. The MFC could not utilize nitrate as a replacement for oxygen in the cathode reactions

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