| Integrated vertical flow constructed wetlands(IVCW),as a new type of ecological sewage treatment method,has the advantages of remarkable comprehensive pollution removal effect,simple operation and management,low energy consumption and high environmental benefits,and is widely used and has the function of landscape science popularization.In order to solve the blockage problem of IVCW system in long-term operation and improve its own landscape science value,this study explored the optimal hydraulic operation mode of IVCW system by using computational fluid dynamics(CFD)numerical simulation technology,and put forward the design idea of IVCW system based on the integration of ecological science vision and landscape aesthetics vision,with a view to providing theoretical and technical support for the optimal design of Integrated vertical flow constructed wetlands.The main research contents are as follows:In order to solve the existence of "black box effect" and intuitively understand the water flow law in wetland,a three-dimensional simplified hydrodynamic model of IVCW system is constructed by CFD technology,and the numerical model is verified by dye tracing experiment.The information of water flow pattern,velocity distribution,water flow direction and particle trajectory between simulation experiment and tracing experiment are compared and analyzed to verify the correctness of the numerical model.In order to optimize and improve the hydraulic efficiency of IVCW system,FLUENT software was used to simulate the fluid movement state in IVCW system,and the effects of different resistance coefficient matrix laying order,layer thickness ratio and hydraulic load on the internal hydraulic performance of wetland were investigated.The results show that when the hydraulic load is 0.7m/d,the substrates are laid in layers,and the order of SM,SL and SS from top to bottom,and the ratio of layer thickness is 1:4:1,the hydraulic efficiency in the wetland is the highest(λ = 0.903).At the same time,a small-scale experiment of IVCW system was constructed to test the pollutant purification effect of numerical simulation under the optimized hydraulic conditions.The results showed that the average removal rates of COD,TP and TN under the optimized hydraulic conditions were 51.1%,55.1% and 41.5%,respectively,and the removal effect was significantly higher than that of the control group and more stable.In order to better meet people’s demand for the landscape value of constructed wetlands,this study combines ecological science with landscape aesthetics.On the basis of hydraulic optimization,the IVCW system is applied to the actual sewage treatment project,and a new design idea of IVCW system is put forward,which is based on the ecological water purification function and takes into account the functions of landscape appreciation and popular science education,so as to coordinate the conflict between environmental engineering and landscape architecture and provide reference for the construction of constructed wetlands and the management of water environment. |
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