Removal of Complex Heavy Metals from Agricultural Waters Using Artificial Wetlands

In order to solve the environmental problems of compound heavy metal pollution in farmland water, a vertical submersible artificial wetland wastewater treatment simulation device was established using different forms of substrate configuration to remediate heavy metal pollution in farmland water.Four groups of artificial wetland systems were constructed in the greenhouse with the substrates of gravel, zeolite, biochar and zeolite-biochar, and the changes of effluent water quality and the effects of nitrogen and phosphorus removal were observed to investigate the long-term treatment effects of different substrates on the wastewater containing composite heavy metals, and the distribution characteristics of the heavy metals in the artificial wetland.The removal rate of each heavy metal by each group of artificial wetland was calculated, and the flux of Cd retention in the wetland system was further analyzed to describe the role of plants in the artificial wetland.The results showed that the effluent from all the devices was in a low dissolved oxygen state, and the pH value gradually decreased.The combined removal rate of heavy metals in wastewater by each group of artificial wetland systems reached more than 70% overall, but the combined removal rates of different heavy metals were different.