A membrane-less constructed wetland microbial fuel cell （CW-MFC） is constructed and operated under continuous flow with a hydraulic retention time （HRT） of 2 d. Fed with glucose, the CW-MFC generates a stable curr...A membrane-less constructed wetland microbial fuel cell （CW-MFC） is constructed and operated under continuous flow with a hydraulic retention time （HRT） of 2 d. Fed with glucose, the CW-MFC generates a stable current density of over 2 A/m3 with a resistor of 1 kΩ and has a chemical oxygen demand （COD） removal efficiency of more than 90% after the startup of 2 to 3 d. A series of systems with the electrode spacings of 10, 20, 30 and 40 cm are compared. It is found that the container with the electrode spacing of 20 cm gains the highest voltage of 560 mV, the highest power density of 0. 149 W/m 3, and the highest Coulombic efficiency of 0.313%. It also has the highest COD removal efficiency of 94. 9%. In addition, the dissolved oxygen （DO） concentrations are observed as the lowest level in the middle of all the CW-MFC reactors. The results show that the more COD is removed, the greater power is generated, and the relatively higher Coulombic efficiency will be achieved. The present study indicates that the CW-MFC process can be used as a cost-effective and environmentally friendly wastewater treatment with simultaneous power generation.展开更多
Plants constitute a major element of constructed wetlands(CWs).In this study,a coupled system comprising an integrated vertical flow CW(IVCW) and a microbial fuel cell(MFC) for swine wastewater tre atment was develope...Plants constitute a major element of constructed wetlands(CWs).In this study,a coupled system comprising an integrated vertical flow CW(IVCW) and a microbial fuel cell(MFC) for swine wastewater tre atment was developed to research the effects of macrophytes commonly employed in CWs,Canna indica,Acorus calamus,and Ipomoea aquatica,on decontamination and electricity production in the system.Because of the different root types and amounts of oxygen released by the roots,the rates of chemical oxygen demand(COD) and ammonium nitrogen(NH4^+-N) removal from the swine wastewater differed as well.In the unplanted,Canna indica,Acorus calamus,and Ipomoea aquatica systems,the COD removal rates were 80.20%,88.07%,84.70%,and 82.20%,respectively,and the NH4+-N removal rates were 49.96%,75.02%,70.25%,and 68.47%,respectively.The decontamination capability of the Canna indica system was better than those of the other systems.The average output voltages were 520±42,715±20,660±27,and 752±26 mV for the unplanted,Canna indica,Acorus calamus,and Ipomoea aquatica systems,respectively,and the maximum power densities were 0.2230,0.4136,0.3614,and0.4964 W/m^3,respectively.Ipomoea aquatica had the largest effect on bioelectricity generation promotion.In addition,electrochemically active bacteria,Geobacter and Desulfuromonas,were detected in the anodic biofilm by high-throughput sequencing analysis,and Comamonas(Proteobacteria),which is widely found in MFCs,was also detected in the anodic biofilm.These results confirmed the important role of plants in IVCW-MFCs.展开更多
To find suitable wetland plants for constructed wetland-microbial fuel cells（CW-MFCs）,four commonly used wetland plants, including Canna indica, Cyperus alternifolius L., Acorus calamus, and Arundo donax, were inves...To find suitable wetland plants for constructed wetland-microbial fuel cells（CW-MFCs）,four commonly used wetland plants, including Canna indica, Cyperus alternifolius L., Acorus calamus, and Arundo donax, were investigated for their electrogenic performance and physiological changes during non-growing seasons. The maximum power output of12.82 mW/m^2 was achieved in the A. donax CW-MFC only when root exudates were being released. The results also showed that use of an additional carbon source could remarkably improve the performance of electricity generation in the C. indica and A. donax CW-MFCs at relatively low temperatures（2–15°C）. However, A. calamus withered before the end of the experiment, whereas the other three plants survived the winter safely, although their relative growth rate values and the maximum quantum yield of PSII（Fv/Fm） significantly declined, and free proline and malondialdehyde significantly accumulated in their leaves.On the basis of correlation analysis, temperature had a greater effect on plant physiology than voltage. The results offer a valuable reference for plant selection for CW-MFCs.展开更多
Constructed wetlands(CWs)are widely used as a tertiary treatment technology,and the addition of carbon sources can significantly improve advanced nitrogen removal.However,excessive carbon sources would lead to an incr...Constructed wetlands(CWs)are widely used as a tertiary treatment technology,and the addition of carbon sources can significantly improve advanced nitrogen removal.However,excessive carbon sources would lead to an increase in the effluent chemical oxygen demand in CWs,and microbial fuel cells(MFCs)can convert these into electricity.In this study,constructed wetland-microbial fuel cells(CW-MFCs)were built to achieve simultaneous nitrogen removal and electricity generation,using wetland plant litter fermentation broths as carbon sources.The total nitrogen removal in the groups with fermentation broth addition(FGs)reached 83.33%,which was 19.64%higher than that in the CG(group without fermentation broth),and the mean voltages in the FGs were at least 2.6 times higher than that of the CG.Furthermore,two main components of the fermentation broths,acetic acid(Ac)and humic acid(HA),were identified using a three-dimensional excitation emission matrix and gas chromatograph and added to CW-MFCs to explore the influence mechanism on the treatment performance.Denitrification and electrogenesis presented the same tendency:Ac&HA>Ac>CG’(groups without Ac and HA).These results indicate that Ac and HA increased the abundance of functional genes associated with nitrogen metabolism and electron transfer.This study demonstrated that CW-MFC fermentation broth addition can be a potential strategy for the disposal of secondary effluent and bioelectricity generation.展开更多
基金The Fundamental Research Funds for the Central Universitiesthe National Natural Science Foundation of China (No.51109038)
文摘A membrane-less constructed wetland microbial fuel cell （CW-MFC） is constructed and operated under continuous flow with a hydraulic retention time （HRT） of 2 d. Fed with glucose, the CW-MFC generates a stable current density of over 2 A/m3 with a resistor of 1 kΩ and has a chemical oxygen demand （COD） removal efficiency of more than 90% after the startup of 2 to 3 d. A series of systems with the electrode spacings of 10, 20, 30 and 40 cm are compared. It is found that the container with the electrode spacing of 20 cm gains the highest voltage of 560 mV, the highest power density of 0. 149 W/m 3, and the highest Coulombic efficiency of 0.313%. It also has the highest COD removal efficiency of 94. 9%. In addition, the dissolved oxygen （DO） concentrations are observed as the lowest level in the middle of all the CW-MFC reactors. The results show that the more COD is removed, the greater power is generated, and the relatively higher Coulombic efficiency will be achieved. The present study indicates that the CW-MFC process can be used as a cost-effective and environmentally friendly wastewater treatment with simultaneous power generation.
基金supported by the Science and Technology Project of the Education Department of Jiangxi Province of China (No.170688).
文摘Plants constitute a major element of constructed wetlands(CWs).In this study,a coupled system comprising an integrated vertical flow CW(IVCW) and a microbial fuel cell(MFC) for swine wastewater tre atment was developed to research the effects of macrophytes commonly employed in CWs,Canna indica,Acorus calamus,and Ipomoea aquatica,on decontamination and electricity production in the system.Because of the different root types and amounts of oxygen released by the roots,the rates of chemical oxygen demand(COD) and ammonium nitrogen(NH4^+-N) removal from the swine wastewater differed as well.In the unplanted,Canna indica,Acorus calamus,and Ipomoea aquatica systems,the COD removal rates were 80.20%,88.07%,84.70%,and 82.20%,respectively,and the NH4+-N removal rates were 49.96%,75.02%,70.25%,and 68.47%,respectively.The decontamination capability of the Canna indica system was better than those of the other systems.The average output voltages were 520±42,715±20,660±27,and 752±26 mV for the unplanted,Canna indica,Acorus calamus,and Ipomoea aquatica systems,respectively,and the maximum power densities were 0.2230,0.4136,0.3614,and0.4964 W/m^3,respectively.Ipomoea aquatica had the largest effect on bioelectricity generation promotion.In addition,electrochemically active bacteria,Geobacter and Desulfuromonas,were detected in the anodic biofilm by high-throughput sequencing analysis,and Comamonas(Proteobacteria),which is widely found in MFCs,was also detected in the anodic biofilm.These results confirmed the important role of plants in IVCW-MFCs.
基金supported by the National Natural Science Foundation of China(No.51308530)the Natural Science Foundation of Hubei Province,China(No.2015CFB558)+1 种基金the National Key R&D Program of China(No.2016YFC0500403-03)the Major Projects of Technical Innovation in Hubei Province(No.2016ACA169)
文摘To find suitable wetland plants for constructed wetland-microbial fuel cells（CW-MFCs）,four commonly used wetland plants, including Canna indica, Cyperus alternifolius L., Acorus calamus, and Arundo donax, were investigated for their electrogenic performance and physiological changes during non-growing seasons. The maximum power output of12.82 mW/m^2 was achieved in the A. donax CW-MFC only when root exudates were being released. The results also showed that use of an additional carbon source could remarkably improve the performance of electricity generation in the C. indica and A. donax CW-MFCs at relatively low temperatures（2–15°C）. However, A. calamus withered before the end of the experiment, whereas the other three plants survived the winter safely, although their relative growth rate values and the maximum quantum yield of PSII（Fv/Fm） significantly declined, and free proline and malondialdehyde significantly accumulated in their leaves.On the basis of correlation analysis, temperature had a greater effect on plant physiology than voltage. The results offer a valuable reference for plant selection for CW-MFCs.
基金supported by the National Natural Science Foundation of China(No.U20A20326)the Fundamental Research Funds for the Central Universities(No.2020CDJDPT002)Chongqing Talents Plan for Young Talents(No.CQY201905062).
文摘Constructed wetlands(CWs)are widely used as a tertiary treatment technology,and the addition of carbon sources can significantly improve advanced nitrogen removal.However,excessive carbon sources would lead to an increase in the effluent chemical oxygen demand in CWs,and microbial fuel cells(MFCs)can convert these into electricity.In this study,constructed wetland-microbial fuel cells(CW-MFCs)were built to achieve simultaneous nitrogen removal and electricity generation,using wetland plant litter fermentation broths as carbon sources.The total nitrogen removal in the groups with fermentation broth addition(FGs)reached 83.33%,which was 19.64%higher than that in the CG(group without fermentation broth),and the mean voltages in the FGs were at least 2.6 times higher than that of the CG.Furthermore,two main components of the fermentation broths,acetic acid(Ac)and humic acid(HA),were identified using a three-dimensional excitation emission matrix and gas chromatograph and added to CW-MFCs to explore the influence mechanism on the treatment performance.Denitrification and electrogenesis presented the same tendency:Ac&HA>Ac>CG’(groups without Ac and HA).These results indicate that Ac and HA increased the abundance of functional genes associated with nitrogen metabolism and electron transfer.This study demonstrated that CW-MFC fermentation broth addition can be a potential strategy for the disposal of secondary effluent and bioelectricity generation.
