Phytoremediation performance of mixed planting patterns and the associated rhizosphere microbial community in pilot-scale constructed wetlands.

Phytoremediation is a low-cost, environmentally friendly, and sustainable technology that can utilize vegetation and microorganisms to avoid eutrophication and purifying water environment. The ability of five different living aquatic plants of nitrogen (N), phosphorus (P), and chemical oxygen demand (CODcr) removal were investigated in pilot scale constructed wetlands (CWs). Aquatic plant mixes significantly improved CODcr removal and plant tissue uptake of nitrogen and phosphorus. The wetland performance of mixed plantings was also influenced by the specific species. The mixed planting of Phragmites australi, Nymphaea Colorado and Myriophyllum verticillatum (PNM)When assessing pollutant removal in CWs, PNM performed better within mixtures, a possible synergistic effect, while TNV Typha orientalis, Nymphaea Colorado, and Vallisneria natans (TNV) performed poorly, a possible antagonist effect. The nutrient uptake within plant tissues byunder mixed plants planting was always ahad synergistic effect. Mixed plantingAquatic plant mixes significantly increased the rhizosphere microbial diversity and promoted the growth of functional denitrifying flora.

Simulation of pollutant diffusion in vegetation open channel based on LBM-CA method.

This paper proposes a pollution diffusion model that accurately assesses changes in instantaneous river pollution in vegetation open channels. The model is established based on cellular automata and lattice Boltzmann method (LBM-CA). Flow influence coefficients are incorporated into cellular automata (CA) to represent the effect of vegetation on pollutant diffusion, while the lattice Boltzmann method (LBM) is utilized to simulate flow in vegetation open channels and obtain the flow influence coefficients for each cellular. The results show that the LBM-CA model has high accuracy and that pollutants tend to accumulate in vegetation areas, thereby extending the residence time of pollutants. The model incorporates pollution limits, allowing the prediction of basin pollution levels at specific times. The LBM-CA model provides a method for simulating pollutant diffusion in natural rivers.

Derivation of new resistance principle on flow-induced morphological response of flexible vegetation.

Water flow under vegetated environments is a noteworthy research topic in environmental hydraulics and restoration ecology, and this research is particularly important for maintaining water transport and streambed stability in water ecosystems. The calculation of the resistance coefficient in vegetated water flow is the core of this research. But there are still problems such as complex expressions and low simulation accuracy in this research field. To solve this scientific problem, this research, based on the theoretical study of environmental hydraulics and genetic algorithm, selected three basic parameters of vegetation submergence, resistance length and curvature degree, and successfully constructed the formula for calculating the resistance coefficient for flexible vegetated flow by using a wide range of data sets. New quantitative relationship between the drag coefficient and the relative roughness of flexible vegetation was established in this study. The formula of drag coefficients for flexible vegetation conditions has a more concise form and can be successfully applied to both flexible and rigid vegetation. As flexible vegetation is deformed under the action of water flow, and the quantitative expressions of Vogel number and relative roughness are given quantitatively through the analysis of its physical properties. Overall, this study improves the basic theoretical study of vegetated flow in environmental fluid dynamics and provides scientific theoretical support for vegetation restoration.