Bioenergy generation, organic matter, and simultaneous nitrogen and phosphorus removal in comparative pyrite and graphite-based constructed wetland-microbial fuel cells at different anode scales
Prince Atta Opoku, Xu Shaowei, Huang Jingyu
Abstract
To examine the comparative impact of pyrite (Py) and graphite (GG) anode fillers in different anode-number configurations of the constructed wetland-microbial fuel cell (CW-MFC), this study constructed two identical multi-anode (MA) CW-MFCs, two single-anode (SA) CW-MFCs, and two standard constructed wetlands (CWs) and evaluated their performances in bioenergy generation, COD removal, and simultaneous nitrogen and phosphorus removal. The results revealed a consistent advantage favoring the pyrite CW-MFCs and CW in power generation, energy recovery, organic matter, and nutrient removal. The Py-MACW-MFC, Py-SACW-MFC, and Py-CW achieved COD removal efficiencies of 92 %, 95 %, and 84 %, which were on average 1.03 times higher than those of GG-MACW-MFC, GG-SACW-MFC and GG-CW, respectively. The Py-MACW-MFC (74 %), Py-SACW-MFC (59 %), and Py-CW (46 %) were also 1.17 times, 1.23 times and 1.24 times higher in NH 4 + -N removal efficiency and produced lower NO 3 − -N and TP effluent concentrations than their respective CW-MFC/CW configurations. The maximum anodic power densities of the Py-MACW-MFC, 25.54 mW/m 3 , 29.14 mW/m 3 , and 23.81 mW/m 3 , for anode 1 (A1), anode 2 (A2), and anode 3 (A3) respectively, as well as its coulombic efficiencies, were higher than those of graphite CW-MFCs. The study demonstrated pyrite anode filler's capacity to outperform graphite's in all parameters and on every reactor scale despite being more affordable and readily available.