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Microbial Activity Influences Electrical Conductivity of Biofilm Anode
Dhar, B., J. Sim, H. Ryu, H. Ren, J. Santodomingo, J. Chae, AND H. Lee. Microbial Activity Influences Electrical Conductivity of Biofilm Anode. WATER RESEARCH. Elsevier Science Ltd, New York, NY, 127:230-238, (2017).
In this study, we evaluated the change of biofilm conductivity in a steady-state biofilm anode in which different proton gradients were built using three phosphate buffer concentrations. First, current density, biofilm thickness, and proton gradients were quantified for individual phosphate conditions. Second, the metabolic activity of ARB within biofilm anodes was qualitatively compared between low and high phosphate buffer using confocal laser scanning microscopy (CLSM). Finally, we experimentally measured Kbio and half-saturation anode potential (EKA) for the biofilm at the three phosphate buffer concentrations and discussed the implication of reduced Kbio at acidic pH.
This study assessed the conductivity of a Geobacter-enriched biofilm anode along with biofilm activity in a microbial electrochemical cell (MxC) equipped with two gold anodes (25 mM acetate medium), as different proton gradients were built throughout the biofilm. There was no pH gradient across the biofilm anode at 100 mM phosphate buffer (current density 2.38 A/m2) and biofilm conductivity (Kbio) was as high as 0.87 mS/cm. In comparison, an inner biofilm became acidic at 2.5 mM phosphate buffer in which approximately 80 μm of the inner biofilm anode was metabolically inactive. At this low phosphate buffer, Kbio significantly decreased by 0.27 mS/cm, together with declined current density of 0.64 A/m2. This work demonstrates that biofilm conductivity depends on metabolic activity of Geobacter in the conductive biofilm anode. The decreased Kbio at acidic environment implies the presence of multiple conduction-EET pathways in the biofilm anode.
Record Details:Record Type: DOCUMENT (JOURNAL/PEER REVIEWED JOURNAL)
Organization:U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
NATIONAL RISK MANAGEMENT RESEARCH LABORATORY
WATER SYSTEMS DIVISION
DRINKING WATER SYSTEMS BRANCH