Microbial Fuel Cells as Effective Tools for Energy Recovery and Antibiotic Detection in Water and Food

Abstract

This work demonstrates that microbial fuel cells (MFCs), optimized for energy recovery, can be used as an effective tool to detect antibiotics in water-based environments. In MFCs, electroactive biofilms function as biocatalysts by converting the chemical energy of organic matter, which serves as the fuel, into electrical energy. The efficiency of the conversion process can be significantly affected by the presence of contaminants that act as toxicants to the biofilm. The present work demonstrates that MFCs can successfully detect antibiotic residues in water and water-based electrolytes containing complex carbon sources that may be associated with the food industry. Specifically, honey was selected as a model fuel to test the effectiveness of MFCs in detecting antibiotic contamination, and tetracycline was used as a reference antibiotic within this study. The results show that MFCs not only efficiently detect the presence of tetracycline in both acetate and honey-based electrolytes but also recover the same performance after each exposure cycle, proving to be a very robust and reliable technology for both biosensing and energy recovery.

Keywords: antibiotic contamination; bio-electrochemical sensors; biosensors; energy recovery; microbial fuel cells.

Figure 1

The structure of the a-SCMFC is proposed in (a) by a render that highlights the inner structure of the single chamber and in (b) by a picture of an actual cell.

Figure 2

Current density production over time: the blue line refers to current density produced by a-SCMFCs running with sodium acetate, and the purple line shows the current density obtained during exposure to tetracycline. Results collected during exposure to antibiotics are magnified and highlighted in the yellow box.

Figure 3

The red curve in the main graph refers to the current density for MFCs fed with honey, while in light blue, the current density produced during exposure to tetracycline is proposed. Current density during exposure to tetracycline is magnified and highlighted in the red box.

Figure 4

Recovered energy (E_rec) calculated for SCMFCs using two different electrolytes: (a) the water-based electrolyte containing sodium acetate only and sodium acetate with tetracycline; (b) honey-based electrolyte and honey with tetracycline added. In both (a,b), Fuel 1 refers to the uncontaminated electrolyte, while Fuel 2 refers to the electrolyte with tetracycline.

Figure 5

(a) Impedance spectra of SCMFCs when sodium acetate with and without tetracycline was used as the electrolyte. Sodium acetate (blue dots and line) and sodium acetate with tetracycline (pink dots and line). (b) Impedance spectra of SCMFCs when honey with and without tetracycline was used as electrolyte. Honey (dark red dots and line) and honey with tetracycline (dark cyan dots and line).