Three-Dimensional X-ray Micro Computed Tomography Of Carbonates And Biofilm On Operated Cathode In Single Chamber Microbial Fuel Cell

Power output limitation is one of the main concerns that need to be addressed for full-scale applica- 28 tions of the microbial fuel cell technology. Fouling and biofilm growth on the cathode of single 29 chamber microbial fuel cells (SCMFC) affects their performance in long-term operation with 30 wastewater. In this study, the authors report the power output and cathode polarization curves of a 31 membraneless SCMFC, fed with raw primary wastewater and sodium acetate for over 6 months. At 32 the end of the experiment, the whole cathode surface is analyzed through x-ray microcomputed to- 33 mography (microCT), scanning electron microscopy, and energy-dispersive x-ray spectroscopy 34 (EDX) to characterize the fouling layer and the biofilm. EDX shows the distribution of Ca, Na, K, 35 P, S, and other elements on the two faces of the cathode. Na-carbonates and Ca-carbonates are pre- 36 dominant on the air (outer) side and the water (inner) side, respectively. The three-dimensional 37 reconstruction by x-ray microCT shows biofilm spots unevenly distributed above the Ca-carbonate 38 layer on the inner (water) side of the cathode. These results indicate that carbonates layer, rather 39 than biofilm, might lower the oxygen reduction reaction rate at the cathode during long-term 40 SCMFC operation