Simultaneous production of bioelectricity and treatment of membrane concentrate in multitube microbial fuel cell

The performance of upflow multitube microbial fuel cell (UM2FC) from membrane concentrate of domestic wastewater (50% concentrate or a volume to concentration ratio of 2) has been investigated in a laboratory test. The test found that the UM2FC with the tin-coated copper mesh and coil spring under different hydraulic retention times (HRTs) produced maximum electricity of 916 ± 200 mW/m3 (61 mW/m2) at an HRT of 0.75 day with a 78% soluble chemical oxygen demand (sCOD) removal efficiency and 3% and 20% Coulombic efficiencies (CEs). The whole-cell resistance as calculated from the Nyquist plot and equivalent circuit were approximately 134 and 255 Ω for HRTs of 0.5 and 0.75 days, respectively. Considering HRT, the current increase with longer HRT could be due to longer contact time between organic material and biofilm, which results in a higher electrical efficiency. The results showed that UM2FC could represent an effective system for simultaneous membrane concentrate treatment and electricity production after further improvements on MFC and operating conditions.