Date of Award
Santa Clara : Santa Clara University, 2020.
The original specific aim of this project was to use a microbial fuel cell (MFC) fueled by the catabolism of E. coli DH5α (pKAU17) bacteria in order generate current as a result of urea degradation. The initial design plan was to test the bacteria outside of the MFC, obtain power measurements,, and finally, construct an electrochemical model that would be compared to an existing theoretical model developed at SCU. Using a 0.25 L anode chamber, graphite electrodes and a sulfonated tetrafluoroethylene based fluoropolymercopolymer proton exchange membrane the galvanic cell was constructed. In response to constraints, the design plan was modified to include testing bacteria outside of the MFC and constructing a bulk liquid model at steady state comparing the time when maximum power output occurs in batch and continuous stirred tank reactor configurations assuming Monod growth.
As determined by experimental results the enzymatic degradation of urea follows first order kinetics with k = 0.0055 min-1. The results of the bulk liquid model show that a batch reactor configuration is recommended for future laboratory work, as maximum power output will occur at 28.8 hours for an initial urea concentration of 2 g/ L, compared to 33 hours for the continuous stirred tank reactor. Of significance is the comparison of the reactor configurations operating at 1 g/ L considered to be the physiological uremic concentration: the time to reach maximum power is approximately seven times for the batch (331.3 hours) versus CSTR (50 hours). With the incorporation of the PEM and multimeter measurements, once these findings are verified additional environmental impacts will be assessed for multiple growth cycles under non steady state conditions.
McMonigal, Ann; Khoilian, Sarah; and Bengford, David, "Optimal Reactor Configuration of a Microbial Fuel Cell Containing Bacteria Genetically Engineered to Degrade Urea" (2020). Bioengineering Senior Theses. 99.