PERFORMANCE OF A MICROBIAL FUEL CELL OPERATED WITH VINASSES USING DIFFERENT COD CONCENTRATIONS

Abstract

Vinasses are one of the main wastes generated from the mezcal industry in Mexico. Due to their high organic matter content and low pH, vinasses have negative environmental impacts if discharged without any treatment. An alternative treatment of vinasses is their use in microbial fuel cells (MFC) for organic matter removal and electricity production. In this paper, the performance of a MFC using vinasses is analyzed. Different organic matter concentrations in terms of chemical oxygen demand (COD) were tested and compared regarding power density, internal resistance, and voltage production. The results demonstrated that the highest COD tested resulted in a poor MFC performance. When using vinasses in MFC for 10 days, COD of 6000 mg/L generated 80.64 W/m3 and when using vinasses with a COD of 17 143 mg/L, the power density dropped to 5.13 W/m3. Further tests of COD performance in MFC were made with 10 640 and 6760 mg/L for 68 days. It was demonstrated that a COD of 10 604 mg/L only produced 0.61 V, while a COD of 6760 mg/L reached 0.81 V. Regarding the organic matter removal, the highest COD removed (92 %) was obtained when using vinasses with a COD of 10 604 mg/L. By operating the cell with 6000 mg/L, COD removal was 83 % and with 17 143 mg/L, 49 %. To achieve a better MFC performance, the organic matter content in the electrolyte should not exceed 6000 mg/L so that the MFC does not achieve a saturated state that hinders the oxidation mechanisms and thus electricity production and COD removal.