Constructed wetlands technology is an important type of wastewater treatment technologies. Compared with other wastewater treatment technologies, the aquatic plants are special components in constructed wetlands for water pollutants removal. However, the comprehensive functions of aquatic plants in constructed wetlands were little emphasized before. In this study, the comprehensive functions and effects of aquatic plants in constructed wetlands to the water pollutants removal are investigated. Multiple common used aquatic plants are compared with their biomass, nitrogen and phosphorus absorption capacity, and oxygen secretion by root systems. These are used to investigate the mechanisms of the functions of aquatic plants in water pollutants removal in constructed wetlands. In this study it is found different types of aquatic plants have different comparable advantages in biomass, nitrogen and phosphorus absorption capacity, and oxygen secretion by root systems. The aquatic plants in constructed wetlands provide dissolved oxygen to the environment around their roots. The aquatic plants themselves have absorption for the nitrogen and phosphorus to directly removal them from the wastewater. Their roots together with the fillers in the constructed wetlands establish the habitat environment for the microorganisms which degrade the water pollutants. The aquatic plants play important and special roles in constructed wetlands for wastewater treatment. These findings can be used for the improvement of the water pollutants removal efficiency in constructed wetlands. The improved constructed wetlands can be used for eutrophication control with higher efficiency.
