Evaluating the Potential of Multi-Anodes in Constructed Wetlands Coupled with Microbial Fuel Cells for Treating Wastewater and Bioelectricity Generation under High Organic Loads

Abstract

Multiple anodes can significantly enhance the treatment potential of constructed wetlands coupled with a microbial fuel cell (CW-MFC) system, which has not yet been explored. Thus, the present study evaluates the potential of multi-anodes and single cathode-based CW-MFC at significantly higher organic loading rates for treatment performance and bioelectricity generation. For this purpose, two identical but different materials, i.e., graphite granules (GG) and granular activated charcoal (GAC), were used to set up multiple anodes and single cathode-based CW-MFCs. The graphite granules (GG)-based system is named CW-MFC (GG), and the granular activated charcoal (GAC) based system is named as CW-MFC (GAC). These systems were evaluated for chemical oxygen demand (COD), NH4+-N removal efficiency, and electrical output at relatively higher organic loading rates of 890.11 g COD/m3-d and 1781.32 g COD/m3-d. At an OLR of 890.11 g COD/m3-d, the treatment efficiency was found to be 24.8% more in CW-MFC (GAC) than CW-MFC (GG), whereas it was 22.73% more for CW-MFC (GAC) when OLR was increased to 1781.32 g COD/m3-d. Whereas, NH4+-N removal efficiency was more in CW-MFC (GG) i.e., 56.29 ± 7% and 56.09 ± 3.9%, compared to CW-MFC (GAC) of 36.59 ± 3.8% and 50.59 ± 7% at OLR of 890.11 g COD/m3-d and 1781.32 g COD/m3-d, respectively. A maximum power density of 48.30 mW/m3 and a current density of 375.67 mA/m3 was produced for CW-MFC (GAC) under an organic loading rate of 890.11 g COD/m3-d.