Microbial fuel cell as a green technology for sludge oxidation and abiotic nitrate reduction: Integration of Taguchi-multi criteria decision method

Utilizing waste in the field of energy production is essential for sustainable waste management. Microbial fuel cell (MFC) has become a clean technology with its ability to treat pollutants with reduction/oxidation characteristics and simultaneously produce energy. In this study, the oxidation of dairy processing industry waste activated sludge and abiotic reduction of nitrate were optimized simultaneously with electricity generation in an MFC by multiple response Taguchi experimental design. The experimental results were optimized for coulombic efficiency (CE), total chemical oxygen demand (TCOD), maximum power density and nitrate removal responses, and three different optimum experimental conditions were obtained according to desirability. The most suitable alternative optimum condition was determined by the PROMETHEE approach. Thermal-acidic pretreatment of the sludge, use of carbon felt/Pt-coated carbon cloth as the anode/cathode electrode and 6.5 × 10⁻⁶ mmol/L methylene blue with NO₃⁻ were determined as the optimum conditions. Under these conditions, the CE, maximum power density, TCOD, and nitrate removal were obtained as 0.72 %, 81.50 mW/m², 24.5 %, and 11 %, respectively. With the optimization in which the maximum power density and CE responses were maximized, a power density of 121 mW/m² and a CE of 1.55 % were obtained.