Algal biofilms, microbial fuel cells, and implementation of state-of-the-art research into chemical and biological engineering laboratories

Abstract

Alternative energy technologies become more attractive as the price of energy from fossil fuels becomes more expensive and the environmental concerns from their use mount. While a number of biological alternative energy technologies currently exist, a complete understanding of these technologies has yet to be developed. This dissertation characterizes an aspect of biological alternative energy technologies: the production of algal biofuels and energy conversion in microbial fuel cells. Specifically, this dissertation addresses the characterization of microalgae as a biofilm and the characterization of the power limitations of microbial fuel cells. The attachment and detachment of algae were observed using temporal microscopic imaging in a flow-cell with autofluorescence and staining techniques as part of a collaborative Montana State University and Idaho National Laboratory project. Colonies of algae exhibit many characteristics seen in bacterial biofilms: adherence; detachment and sloughing; difference in structure of an attached colony; varying strength of attachment on different surfaces; association of other organisms in an EPS matrix; and the heterogeneous nature of attached colonies. The characterization of a microbial fuel cell was completed in less than 30 minutes using an empirical procedure to predict the maximum sustainable power that can be generated by a microbial fuel cell over a short period of time. In this procedure, the external resistance was changed incrementally, in steps of 500 ohms every 60 seconds, and the anode potential, the cathode potential, and the cell current were measured. This procedure highlights the inherent limitations of energy conversion in a microbial fuel cell. A voltage/current characterization of the microbial fuel was also completed from the data collected. This dissertation also includes the evaluation of A Hands-On Introduction to Microbial Fuel Cells, a laboratory developed for an introductory chemical and biological engineering course. The experiment has been updated to include a voltage/current characterization of the microbial fuel cell. Learning objectives have been identified and pre- and post-laboratory activities have been developed for further implementation into a chemical and biological engineering curriculum.