Air-exposed microbial fuel cells and screening techniques

Air-exposed microbial fuel cells and screening techniques" (2010). Introduction: Internal resistance (R int) of microbial fuel cells (MFC) has been identified as a significant variable associated to cell power output and low values are desirable (Du et al., 2007). Therefore , the aim of this research was to evaluate the effect of inoculum type and architectural features of MFC (separation of electrodes and increase of ␰ specific surface or surface area of electrode to cell volume) on R int of MFC. Methods: A new design of a single chamber MFC-A was based on extended electrode surface (larger ␰) and the assemblage or 'sand-wich' arrangement of the anode-PEM-cathode (Liang et al., 2007; Vazquez-Larios, 2009). The standard cell MFC-B was built with separated electrodes. Both cells were tested with several inocula (sulphate-reducing, SR-In; methanogenic, M-In, and aerobic, Ab-In) in order to determine their effects on the internal resistance R int and other electrical characteristics of the cells. Results: Typical polarization curves of the cells using sulfate-reducing inoculum are shown in Fig. 1a. In general, R int of the new design cell MFC-A was consistently lower than that of the standard MFC-B (p < 0.037) (Fig. 1b). Regarding the effect of inoculum, resistances followed the order R int,SR-In < R int,M-In « R int,Ab-In with a statistical significance p < 0.0001 (Fig. 1b). Volumetric power P V output of MFC-A was higher than that of MFC-B (Table 1); this was congruent with doubling the ␰ in the MFC-A compared to MFC-B. Yet, power density P An delivered was