Modification of Electrodes for MFC Using Sludge from the Wastewater Treatment Plant

Carbon Vulcan XC 72R was modified using several chemical treatments (oxidation in acidic medium, ethylene glycol, 4-aminopyridine and rubeanic acid treatments) changes in the electrochemical behavior and the surface composition were observed. Pieces of carbon tissue were modified with the carbon materials. The pieces of carbon tissue were electrochemically characterized and used as anodes in a single chamber air cathode MFCs (Microbial Fuel Cells ) inoculated with sludge from the Wastewater Treatment plant of La Voragine, yielding a maximum power density of 15.37 mWm^-2 and a maximum current density of 61.25 mAm^-2 for the cell with the electrode modified with ethylene glycol. To compare the performance of the anodes were measured anodic polarization curves, which showed better performance for the rubeanic acid modified electrode. The lower performance was obtained for the unmodified electrode followed by electrode modified by chemical oxidation. These results suggest a reduction in biocompatibility by the introduction of negatively charged groups.

The results of the cultivation and isolation of microorganisms in the anode showed a greater affinity of the bacteria for the rubeanic acid modified electrode and the exclusive presence of a microorganism in it. Additionally was observed the presence of redox mediators producing bacteria on the electrode modified by oxidative treatment. The results show the influence of the surface composition on the biofilm composition and probably in the electron transfer mechanism.