ABSTRACT: Microbial electro chemistry is a cross-disciplinary field that has become a "hot" topic in environmental engineering and science. The microbial electro chemical cell (MxC) is a technology platform for removing biochemical oxygen demand (BOD) from organic wastes while generating valuable outputs. The unique feature of MxCs is the bio film of anode respiring bacteria (ARB) that live on the anode, oxidize organic molecules, and efficiently respire the electron to the anode by extracellular electron transport (EET). Valuable outputs depend on the reduction reaction at the cathode: They include electrical power, hydrogen gas, hydrogen peroxide, and acetate. Those wanting to create viable MxC technologies need to recognize four important ironies about what actually controls the performance of an MxC. (1) Although the unique features of an MxC are the ARB and EET of electrons to the anode, the anode's current density is determined by the diffusion of protons out of the bio film, which depends on a weak-base buffer. (2) The main energy loss in an MxC is at the cathode, and minimizing cathode over-potential depends on the transport of hydroxide away from the cathode with a weak-acid buffer. (3) Selection and accumulation of the most efficient ARB in the bio film anode is brought about by using a "stressful" negative anode potential, even though a high anode potential gives the fastest EET once the bio film is established. (4) Efficient ARB have adaptable EET that takes advantage of changes of potential and pH within the bio film.

BIOGRAPHY:
Dr. Bruce E. Rittmann is Regents' Professor of Environmental Engineering and Director of the Biodesign Swette Center for Environmental Biotechnology at Arizona State University. His research focuses on the science and engineering needed to "manage microbial communities to provide services to society." Services include generating renewable energy, cleaning water and soil, and improving human health. Dr. Rittmann is a member of the National Academy of Engineering; a Fellow of AAAS, WEF, IWA, and NAI; and a Distinguished Member of ASCE. Dr. Rittmann was awarded the first Clarke Prize for Outstanding Achievements in Water Science and Technology from the NWRI, the Walter Huber Research Prize and the Simon Freese Award from ASCE, the G.M. Fair Award from AAEES, and the Perry L. McCarty/AEESP Founders Award. Dr. Rittmann has published over 610 journal articles, books, and book chapters, and he has 15 patents. With Dr. Perry McCarty, Dr. Rittmann co-authored the textbook Environmental Biotechnology: Principles and Applications(McGraw-Hill Book Co.).

This event is related to:

The Water Environment
Environmental Engineering and Science Program