INFLUENCE OF EXTERNAL RESISTANCE AND ANODIC pH ON POWER DENSITY IN MICROBIAL FUEL CELL OPERATED WITH B. SUBTILIS BSC-2 STRAIN

Abstract

Microbial fuel cells (MFCs) are bioelectrochemical devices able to convert chemical energy into electricity. The selection of anodic pH and external resistances play a significant role in the overall performance of the device. This research presents the effect of operational conditions of the MFC using B. Subtilis in anode. The effect of pH and external resistance were determined by 3 2 full factorial design. Data were analyzed statistically by ANOVA and p ≤ 0.05 was considered statistically significant. The surface response analysis evidenced interaction and quadratic effect of the pH and external resistance on the power density generation. With a second-order polynomial model the optimum conditions of the system were determined. It maximized the power at pH of 8.6 and an external resistance of 220 Ω, delivering power density of 405 mW/m 2 . The chemical oxygen demand (COD) removal efficiency and coulombic efficiency (CE) were 82% and 15%, respectively. The maximum specific growth (µ) and substrate uptake (k 1 ) rate for electrochemically active bacteria (EAB) at optimum conditions were 0.19/h and 0.019/h respectively. These experimental results show the importance of the simultaneous effect of pH and external resistance, which is even more influential then if they were studied separately.

Application of Magnetite-Nanoparticles and Microbial Fuel Cell on Anaerobic Digestion: Influence of External Resistance

“…The cell potential adjusts to the external resistance [ 49 ]. As the MFC is a source of voltage (V), where deviations taking place on the voltage can be regarded insignificant, in other words, lower frequency [ 50 ], the maximum power transfer theorem suggests that optimum power is generated when internal resistance (R int ) and external resistance (R ext ) of electricity source are equal to each other. It can be said that the power produced (P) is a function of current (I).…”

“…Stability may be described by the concepts of resilience (the system’s recovery rate after a disturbance) and resistance (the system’s ability to withstand disturbance) [ 53 ]. Therefore, the choice of external resistances and pH of the system play a vital role in the total efficiency of the microbial fuel cell [ 50 ]. Figure 11 depicts the influence of digester type on process stability as a measure of pH.…”

“…The highest maximum power density of 30.17 mW/m 2 was achieved at a pH of 8.60. Cordova-Bautista et al [ 50 ] investigated the effect of external resistance and anodic pH on power density in MFC and found that the best-performing digester produced the highest power density of 405 mW/m 2 at a pH of 8.60. On the other hand, a low power density of 0.83 mW/m 2 and low pH value of 7.28 on the 1000 Ω digester indicated a loss of electrochemically active microbes probably due to the high build-up of protons and autotrophic microbes in the system.…”