Constructed Wetland Microbial Fuel Cells Enhanced With Zero-Valent Iron For Wastewater Treatment And Power Generation

Zero-valent iron（ZVI）in combination with vertical flow constructed wetland microbial fuel cell system（CWMFC）was used in this study.The generation of biomass electric energy in the treatment of wastewater by group-zero-valent iron（ZVI）and group non-zero-valent iron（CK）was studied by the introduction of artificial municipal sewage.By analyzing and comparing the relative abundance of microbial community and functional microbial groups of inoculated raw sludge and two groups of CWMFC anode sludge,the effect of water purification and the conclusion of electric power generation were expounded.Zero-valent iron（ZVI,iron chips）in combination with constructed wetland microbial fuel cells（CWMFC）treat municipal wastewater,and compared the ZVI system with the common system.The addition of ZVI can improve the ability of CWMFCs to treat municipal wastewater and generate electricity,and significantly increase the COD removal rate（79%）（P<0.05）.NH₄⁺-N,TN and TP removal efficiency in the system is not very obvious.On the power performance of the CWMFC,ZVI group achieved a voltage of 326m V with the highest power density of 2.03 m W·m^-2.There was significant difference in the power production capacity of ZVI group compared with CK group（P<0.05）;The OTU values of anode ZVI（A）in experimental group were higher than those in control group CK（A）from device start to stable operation.The characteristics of richness index Chao1,Observed-species and diversity index Simpson and Shannon measured separately.It is fully proved that the microbial richness and diversity in ZVI group are higher than that in CK group.ZVI can promote the enrichment of some microorganisms in the system and provide a suitable growth environment for microorganisms by ZVI/AC microelectrolysis.The microbes in the system gradually adapt and gather in the electric field environment,which makes the device produce stronger electricity,and the stronger electric field environment will promote the growth of the internal microbial community and form a cycle.The zero-valent iron in combination with CWMFC system constructed in this study will have better performance in the treatment of municipal wastewater than the common CWMFC.This study proposes a new strategy to improve the performance of CWMFC and provides a theoretical basis for the treatment of wastewater with high COD.