Simultaneous energy harvest and nitrogen removal using a supercapacitor microbial fuel cell. (November 2020)

• Record Type: Journal Article
• Authors: Cai, Teng; Jiang, Nan; Zhen, Guangyin; Meng, Lijun; Song, Jialing; Chen, Gang; Liu, Yanbiao; Huang, Manhong
• Is Part Of: Environmental pollution. Volume 266:Part 2(2020)
• Publication Date: 2020-11
• Subjects: Carbon nanofiber -- Extracellular electron transfer -- Landfill leachate -- Nitrogen conversion -- Power generation -- Supercapacitor microbial fuel cell; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2020.115154
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: The insufficient removal of pollutants and bioelectricity production have become a bottleneck for high-concentration saline wastewater treatment through microbial fuel cell (MFC) technology. Herein, a novel supercapacitor MFC (SC-MFC) was constructed with carbon nanofibers composite electrodes to investigate pollutant removal ability, power generation, and electrochemical properties using real landfill leachate. The possible extracellular electron transfer and nitrogen element conversion pathways in the bioanode were also analyzed. Results showed that the SC-MFC had higher pollutant removal rates (COD: 59.4 ± 1.2%; NH4 + -N: 78.2 ± 1.6%; and TN: 77.8 ± 1.2%), smaller internal impedance Rt (∼6 Ω), higher exchange current density i0 (2.1 × 10 −4 A cm −2 ), and a larger catalytic current j 0 (704 μA cm −2 ) with 60% leachate than those with 10% and 20% leachate, resulting in a power output of 298 ± 22 mW m −2 . Ammonium could be incorporated by chemoautotrophic bacteria to produce organic compounds that could be further utilized by heterotrophs to generate power when biodegradable organic matters are depleted. Three conversion pathways of nitrogen might be involved, including NH4 + diffusion from anode to cathode chamber, nitrification, and the denitrification process. Additionally, cyclic voltammetry tests showed that both the direct electron transfer (DET) and the mediator electron transfer in bioanode were involved and dominated by DET. The microbial analysis revealed that the bioanode was dominated by salt-tolerant denitrifying bacteria (38.5%), which was deduced to be the key functional microorganism. The electrochemically active bacteria decreased significantly from 61.7% to 4% over three stages of leachate treatment. Overall, the SC-MFC has demonstrated the potential for wastewater treatment along with energy harvesting and provides a new avenue toward sustainable leachate management. Graphical abstract: Image 1 Highlights: A novel supercapacitor MFC was designed to treat landfill leachate. Superior catalytic activity of as-prepared electrode led to high power output. Three conversion pathways of nitrogen were involved in bioanode. Electron transfer in bioanode was dominated by direct electron transfer. High salt-tolerant denitrifying bacteria extensively existed in bioanode.