Effect of Using a Ceramic Separator on the Performance of Hydroponic Constructed Wetland-Microbial Fuel Cell

Abstract

Lack of proper physical separation between the anodic and cathodic zones of a constructed wetland-microbial fuel cell (CW-MFC) causes higher oxygen diffusion into the anodic zone, which leads to nonproductive electron losses. In this investigation, performance of two upflow hydroponic CW-MFCs with a low-cost ceramic separator (R1) and without a separator (R2) was evaluated with Canna indica at the cathodic side. The chemical oxygen demand removal efficiencies of R1 and R2 were found to be 86.2 ± 8.1% and 91.5 ± 4.9%, respectively. However, from the polarization plots, internal resistance of R1 (240 Ω) was found to be 2.6 times lower than that of R2 (626 Ω). In addition, it was revealed that R1 (258.78 mW·m−3) exhibited almost three times higher power density than R2 (91.02 mW·m−3). The normalized energy recovery of the CW-MFC with a ceramic separator was also 2.7 times higher than that without a separator. The presence of a separator thus facilitated better anaerobicity to support substrate utilization by electrogenesis in the anodic zone of R1 and prevented oxygen diffusion, which resulted in higher energy recovery while only marginally compromising the efficiency of organic matter removal.