A comparative study of different electrochemical methods to determine cell internal parameters of microbial fuel cells

The efficient energy recovery from wastewater through microbial fuel cells (MFC) depends on a comprehensive understanding of the electrochemical properties of the system. Different methods to infer electrochemical parameters can be applied. However, the absence of studies confirming the compatibility and inter-validity of these methods makes their comparison difficult. In this study six different electrochemical methods were compared in triplicate MFCs: i) varying circuit resistance (VCR); ii) linear sweep voltammetry (LSV); iii) current interruption (CI); iv) electrochemical impedance spectroscopy (EIS); v) pulse width modulation (R-PWM); and vi) the perturbation observation (P/O) algorithm. Comparative investigations of the ohmic resistances from CI (73.0 ? 11.4 0), EIS (70.8 ? 11.1 0) and R-PWM (73.3 ? 11.2 0) showed high agreement. Further analysis of the activation resistances using detailed model-based methods, such as EIS (26.0 ? 10.9 0) and R-PWM (25.0 ? 3.0 0) demonstrated that both methods provide identical results. The applicability of the R-PWM mode as a real-time optimization method can be supported by the calculated maximum power densities from VCR and LSV together with the adjusted resistance from the P/O algorithm. In R-PWM mode theoretical power densities up to 95% of the maximum power point can be achieved.

Automated summary

This study compares six different electrochemical methods in MFCs, showing high agreement in ohmic resistance and activation resistance for some methods. The R-PWM mode is demonstrated as real-time optimization method with theoretical power densities up to 95% of the maximum power point achievable.