Abstract
The utilization of microbial fuel cells (MFCs) for regulating greenhouse gas (GHG) emissions in constructed wetlands (CW) has attracted significant attention. The impact of structural modifications, the introduction of iron-carbon materials on pollutant removal and GHG release from MFC-CW has not been systematically studied. In this study, four types of MFC-CWs were constructed, including MFC-CW with separated aerobic and anaerobic zones (SC), MFC-CW with unseparated aerobic and anaerobic zones (IC), SC added with iron-carbon (SFC), and IC added with iron-carbon (IFC). The aim was to investigate the effects of structural changes and electron shuttle additions on the GHG release. The results revealed that IFC simultaneously enhanced pollutant removal and GHG emissions reduction, compared to IC. However, no significant enhancements were observed in SC and SFC. The cumulative emissions of nitrous oxide (N2O) and methane (CH4) in SC were reduced by 51.83% and 89.33% respectively, compared to IC. The modifications made to the structure of MFC-CWs influenced the relationship between functional bacteria (Chlorobium, Azospira, and Denitratisoma) and electrochemically active bacteria (EAB), resulting in increased values of nirS/nosZ and pmoA/mcrA. Comparing the SFC and IFC, despite an improvement in denitrogenation efficiency, the effect of structural alteration on N2O reduction was slight. The electrons in the iron-mediated process were not effectively used for N2O reduction. This study confirmed the crucial involvement of electron shuttles and the structure of MFC-CWs in controlling contaminant removal and GHG emissions.
Published Version
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