Improved dynamic response and range in microbial fuel cell-based volatile fatty acid sensor by using poised potential

Low-cost measurement of the concentration of key volatile fatty acids (VFAs) would be very useful to improve the operation of a number of important bioprocesses, through monitoring and control. In situ microbial fuel cells (MFC)-based VFA sensors could replace the current generation of relatively complicated and expensive techniques for online VFA analysis. Cyclic voltammetry (CV) was used to determine the oxidation peak potentials for three VFA species (acetic, butyric and propionic). The dynamic behaviours and static sensitivities were recorded for 10-ml single chamber cubic MFC-based VFA sensors, separately acclimated on acetate, butyrate and propionate, while the anode was poised at a potential corresponding to the oxidation peak from CVs. The current responses at the fixed working electrode potentials were analysed for each VFA sensor in response to different concentration (0-250 mg/L) of the corresponding and other VFA species. When corresponding VFAs were supplied to the sensors, the range of the sensor was increased from 40 to 220 mg/L with no response to other VFA species in acetate- and propionateenriched reactors.