Michaelis–Menten equation considering flow velocity reveals how microbial fuel cell fluid design affects electricity recovery from sewage wastewater

Abstract

Hydrodynamics has received considerable attention for application in improving microbial fuel cell (MFC) performance. In this study, a method is proposed to calculate the effect of fluid flow on MFC current production from sewage wastewater. First, the effect of flow velocity in an up-flow channel was evaluated, where an air-core MFC was polarized with external resistance (Rext). When tested at a flow velocity ranging from 0 to 20 cm s−1, the MFC with the higher flow velocity produced more current. In sewage wastewater with a chemical oxygen demand (COD) of 76 mg L−1, the MFC polarized with 3 Ω of Rext, and a flow velocity of 20 cm s−1 had 5.4 times more current than the MFC operating in a no-flow environment. This magnitude decreased with higher Rext and COD values. The Michaelis–Menten equation, modified herein by integrating COD and flow velocity, demonstrated the production of current by MFC operating under different conditions of flow. Calculation of current by MFC in a virtual fluid suggested that the flow surrounding the MFC varied with the configuration and affected the current production.