Date of Award

12-2013

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Biosystems Engineering

Advisor

Drapcho, Caye M

Committee Member

Walker , Terry

Committee Member

Nghiem , Nhuan

Abstract

The production of biological hydrogen is an important process for the future of sustainability and alternative energies. Thermotoga neapolitana is a hyperthermophilic bacterium that produces H 2 , CO2 and acetate via fermentation. The goal of the research was to investigate the sustainable production of H2 gas using waste agricultural feedstocks, recycled water and a simplified N2 sparging method technique. A limited sparging method was developed which includes 1 minute of N2 gas sparging of the reactor headspace and 90 minutes of idle reaction time for cysteine-HCl to react with dissolved oxygen prior to inoculation. This method was found to increase the hydrogen percentage in the gas produced by Thermotoga neapolitana as compared to a 15 minute sparge, no-idle treatment. In the carbon and nitrogen source study, H2 concentrations as high as 33.08 mmol H2 /L medium were achieved and yields as high as 0.38 g H2 /g substrate COD were achieved using cull peach medium. Soybean or canola meal can act as carbon and nitrogen sources for this process. When waste water from a peach cooling process was used in medium, 35.04 mmol H2 /L medium resulted as compared to the 31.66 mmol H2 /L medium produced using distilled water. These results indicated that the hydrocooler water may be beneficial for the productivity of Thermotoga neapolitana . Thermotoga neapolitana was found to be able to grow in a CSABR reactor at a temperature of 77°C. It was found that when the pH was controlled at 7 and H2 gas was collected the product concentrations were increased compared to the same treatments grown in serum bottles without pH control and H2 gas removal. An alternative medium consisting of peaches and soybean meal as the carbon and nitrogen sources, respectively, was successfully used to grow T . neapolitana in the CSABR system. It was also determined that Thermotoga neapolitana can thrive and product formation can be increased at substrate concentrations of 10 g/L compared to 5 g/L. The 10 g/L Standard medium treatment resulted in a H2 concentration of 83.19 mmol H 2 /L medium compared to 42.66 mmol H2 /L medium for the 5 g/L standard medium.

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