Effective toxicity assessment of synthetic dye in microbial fuel cell biosensor with spinel nanofiber anode

Textile dyes are one of the most commonly found contaminants in wastewater requiring their insitu real-time monitoring and biotreatment. In the present study, two different microbial fuel cells with plain and magnesium ferrite coated stainless steel mesh (PBS/SS and PBS/MF-SS) bioanodes were tested for the simultaneous biosensing and biotreatment of three different concentrations of Ponceau BS dye with mixed microbial community as biological sensing elements. The study revealed the direct correlation of added toxicant and the performance of microbial fuel cell biosensor and observed an almost perfect linear fit for concentration vs. voltage output graph corroborating the potential of microbial fuel cell as a toxicity detector. The cyclic voltammetry confirmed the bioactivity of microbial fuel cell reactor with reference to the unacclimated system. In addition, the cyclic voltammetry analysis of microbial fuel cells at different dye concentration suggested its promising toxicity sensing potential. Electrochemical Impedance Spectroscopy data confirmed that biofouling affected the internal resistances of microbial fuel cells. In addition, the effect of extended run-time (of a year) on the performance of microbial fuel cell was established by comparing the voltage outputs of this study with our previous work. As compared to the previous study, the voltage output for microbial fuel cells with plain and magnesium ferrite coated stainless steel mesh showed a decline by nearly 53% and 41% respectively suggesting the fouling of system. The lesser drop in the performance for microbial fuel cell with modified electrode showed the potential of modified electrode in more efficient electron transfer in the long run. The results conclude that the microbial fuel cell biosensor provides a quick and effective approach for real-time monitoring of hazardous and recalcitrant contaminants such as dyes in environmental samples; nevertheless, fouling of the system is a significant impediment to the long-term practical implementation of microbial fuel cells.