Effect and Mechanism of Applying Myriophyllum Verticillatum for Reclaimed Water Purification in Urban Rivers

Abstract

Reclaimed water produced via the advanced treatment of domestic wastewater has broad application prospects for reuse in urban rivers, while the nutrients in reclaimed water, especially nitrogen and phosphorus, lead to eutrophication or ecological impacts. Submerged plants are preferred as an enhanced technology used at reclaimed water recharge sites for both water quality improvement purposes and ecological conservation functions. In this study, which adopted the typical submerged plant Myriophyllum verticillatum (M. verticillatum) as its experimental object, experiments were carried out in an illumination incubator without a substrate and under hydrostatic conditions to investigate the water purification effects and mechanisms of action of M. verticillatum at different planting densities. The analysis showed that the group with a wet weight of 2.5 g L−1 had the best growth status and the best overall performance with respect to improvements in water quality indicators, including COD, nitrogen, and phosphorus, as well as demonstrating excellent uptake and synergistic effects in the process of removing nitrogen and phosphorus. The contributions of natural effects, the uptake and enrichment by M. verticillatum itself, and the synergistic effects during the nitrogen and phosphorus removal process were quantified. Furthermore, 16S rRNA gene sequencing was used to determine the surface-attached bacterial colonies of M. verticillatum, to analyze their population diversity, and to identify environmental functional genera. In conclusion, an appropriate density of M. verticillatum can improve water quality and provide a suitable environment for the survival and growth of relevant environmentally functional microorganisms, effectively removing nitrogen and phosphorus through its own absorption and synergistic effects.

Assessment and Comprehensive Evaluation of Large-Scale Reclaimed Water Reuse for Urban River Restoration and Water Resource Management: A Case Study in China

“…As many studies have proven, the ecological and water quality conditions of the receiving water body for reclaimed water reuse are closely linked to its baseline conditions, reclaimed water quality, and other relevant factors. Relying solely on reclaimed water to enhance river water quality and aquatic ecosystems is insufficient, so it is necessary to implement in situ ecological restoration measures to further purify water quality and improve the aquatic ecosystem [30,31]. Building on these improvements, the implementation of ecological restoration measures including submerged plant cultivation in key river sections can further purify the water quality, promote the attainment of water environmental quality standards in corresponding functional zones of the river, and reduce the risk of algal blooms.…”