The influence of incorporating microbial fuel cells on greenhouse gas emissions from constructed wetlands
2019
Wang, Xiaoou | Tian, Yimei | Liu, Hong | Zhao, Xinhua | Peng, Sen
Microbial fuel cells (MFCs) were incorporated into constructed wetlands (CWs) in recent years aiming to enhance the wastewater treatment of CWs while simultaneously produce electricity. However, currently no information is available about the greenhouse gas (GHG) emissions from integrated CW–MFC systems during wastewater treatment. Therefore, this study investigated the influence of incorporating MFCs on GHG (especially CH4 and N2O) emissions from CWs under different external resistances, influent organic loadings and seasons. Results showed that incorporating the MFC significantly reduced the GHG emissions (by 5.9%–32.4% CO2 equivalents) from CWs by reducing 17.9%–36.9% CH4 and 7.2%–38.7% N2O emissions. The CH4 and N2O emissions from CW–MFCs significantly increased with increasing external resistance (above 500 Ω), while the CO2 emission showed the opposite trend. However, the CH4 and N2O emissions at external resistances below 500 Ω did not differ significantly. There was a significant positive correlation between the CO2 and CH4 emissions and influent organic loadings in CW–MFCs, but a significant negative correlation between the N2O emission and influent organic loadings. Influent chemical oxygen demand/total nitrogen (COD/TN) = 3 could result in a TN removal of ≥90% as well as the minimum CO2 equivalents emission in CW-MFCs. The GHG emissions from CW–MFCs showed significant seasonal variations.
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