Date of Award

Spring 6-8-2020

Document Type

Thesis

Degree Name

Master of Science (MS)

First Advisor

Zhiyong Jason. Ren

Second Advisor

Pin-Ching Maness

Third Advisor

Chris Corwin

Abstract

Clostridium thermocellum is among the most efficient bacteria to convert cellulosic biomass into H2 during dark fermentation. However, despite great progress the H2 yield and rate are still not satisfactory for large scale applications. The purpose of this study was to evaluate whether in-situ gas extraction using membrane bioreactors would increase H2 production from Clostridium thermocelllum when compared to a conventional anaerobic fermentation setup. Clostridium thermocelllum ATCC 27405, a cellulotyic, thermophilic bacterium was grown on cellobiose and Avicel in an anaerobic-fermentor (AF) and an anaerobic-membrane-bioreactor (AnMBR). Compared to the AF, the ANMBR increased cumulative H2 production by 63%, from 25.8 to 42.1 mmols, increased the max H2 rate by 24%, from 3.4 to 4.2 mmol/hr, and increased yield by 58%, from 0.43 to 0.68 mmol H2/mmol hexose, on cellobiose. Likewise, on Avicel, the AnMBR increased cumulative H2 production by 47%, from 46.8 to 68.6 mmols, increased the max H2 rate by 87%, from 3.1 to 5.8 mmol/hr, and increased the yield by 46%, from 0.76 to 1.11 mmol H2/mmol hexose.Overall, this study indicates that membrane gas extraction reduces feedback inhibition and makes AnMBR more efficient in converting biomass to renewable H2.

Available for download on Sunday, October 31, 2021

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