Improved electricity production and nitrogen enrichment during the treatment of black water using manganese ore-modified anodes

The decline of fossil fuel availability is calling for alternative energy such as electricity produced by degradation of waste in microbial fuel cells. The performance of microbial fuel cells is controlled by the anode because microorganisms grow and attach on the anode. Here, we prepared carbon felt electrodes modified with manganese ore based on the hypothesis that manganese and silicon oxides would improve the cell performance to treat simulated black water. We compared properties of the manganese ore-modified electrodes with properties of classical carbon felt electrodes modified with magnetic ferroferric oxide. We also studied the removal of the chemical oxygen demand and the enrichment in ammonia nitrogen. Results show that the maximum voltage of the manganese ore-modified carbon felt electrode is 1.7 times higher than that of the magnetic ferroferric oxide-modified carbon felt electrode. The start-up time to reach the maximum voltage is reduced by 68%. The removal of chemical oxygen demand reached 91.2%. Up to 68.0% of ammonia nitrogen can be enriched at the cathode, implying that ammonia nitrogen can be highly reduced in the effluent. Overall, the manganese ore-modified carbon felt electrode showed excellent redox performance, excellent corrosion resistance and low electron transfer resistance.

Automated summary

In this study, carbon felt electrodes modified with manganese ore and magnetic ferroferric oxide were compared. The manganese ore-modified electrode showed a maximum voltage 1.7 times higher than the magnetic ferroferric oxide-modified electrode. The start-up time was reduced by 68%. The removal of chemical oxygen demand reached 91.2% and the enrichment in ammonia nitrogen was up to 68.0%.