Effects of a hydraulic series connection and flow direction on electricity generation in a stack connected with different volume mfcs

Abstract

Three microbial fuel cells (MFCs) with different volumes (S-, M-, and L-MFCs) were operated at individual flow (phase I) and serially connected flow modes (phase II for forward flow and phase III for reverse flow) at the same flow rate. The three MFCs showed different voltages and power generation according to the hydraulic and electric connection modes. The M-and L-MFCs showed a similar voltage at hydraulic series-forward flow mode (phase II). The principal component analysis (PCA) and Pearson correlation showed that voltage generation and power density were affected by volume, hydraulic retention time (HRT), chemical oxygen demand (COD) loading rate, removed COD, and internal resistances. When they were connected electrically in series and parallel, the stack showed relatively lower voltage loss (28–30%) compared to the voltage losses of the other stacks (43–94%). These results suggest an easy way to connect MFCs with different volumes can be a new option to avoid voltage reversal and minimize energy loss.