Evaluation of simultaneous energy production and biotic and abiotic nitrate removal in microbial fuel cells (MFCs): Selection of the most suitable MFC by a multi-criteria decision methodology

Abstract

Microbial fuel cell (MFC)’s are sustainable resource recovery technologies that produce green energy. While sewage sludge fed with dairy industry wastewater was oxidized in the anode, the energy production and treatment potentials of MFCs in which nitrate was reduced under abiotic-biotic conditions in the cathode compartment were evaluated. It was determined how the performance changed when the conditions of the cathode compartment were changed as biotic (heterotrophic-autotrophic) and abiotic. The performance of the MFC was evaluated by anodic and cathodic coulombic efficiency (CE), maximum power density, chemical oxygen demand (COD) and NO₃^- removal. Considering the MFC performance criteria and the cost of the carbon source added to the catholytes, the preference order of the MFCs was determined using a multi-criterion decision methodology called the PROMETHEE approach, which allowed for pairwise comparison of alternatives on a criterion basis using preference functions. Accordingly, abiotic MFC˃autotrophic MFC˃heterotrophic MFC preference order was obtained. It was revealed that all criteria except nitrate removal efficiency had a positive effect on the selection of abiotic MFC. Although the nitrate removal efficiency in abiotic MFC was lower than biotic MFCs, the energy production performance was determined to be quite high.