Transformation of N and S pollutants and characterization of microbial communities in constructed wetlands with Vallisneria natans

Abstract

The simulated constructed wetland with Vallisneria natans was studied for the migration and transformation of dissolved oxygen, nitrogen and sulfur pollutants and characterization of microbial community under different concentrations (7.5, 15, 22.5, 30 mgN/L) of NH4+-N. Results indicated that the recovery rate of DO was 0.027–0.07 mg/h, and the removal rate of NH4+-N was over 90%. Meanwhile, S2− was generated into different forms when the DO and the sulfate concentration were below 1 mg/L and over 100 mg/L, respectively. In addition, 16S rRNA sequencing analysis showed that after 30 days, the microbial diversity in both sediments declined, while that in the biofilms of leaves increased by 16.42%. Overall, Vallisneria natans can change microbial communities by releasing oxygen and provide attachment system to form biofilms. When Cinlet(NH4+-N) < 22.5 mgN/L, Cinlet(SO42−) < 135 mg/L, Vallisneria natans can effectively prevent water quality deterioration and strengthen the in-situ self-purification ability of water.