进出水位置对水平潜流人工湿地水力效率影响及可视化分析研究

Hydraulic efficiency of horizontal subsurface flow constructed wetlands with different inlet-outlet location configuration and its visual analysis

通过对水平潜流人工湿地9种不同进出水方式进行NaCl脉冲示踪实验,得到不同进出水方式下的水力停留时间分布密度曲线,计算其平均水力停留时间、表观水力停留时间、峰值停留时间等水力学参数,根据不同停留时间的对比关系计算相对水力效率。此外,利用染料进行不同进出水方式下的可视化示踪实验,通过MATLAB图像处理,获得高对比度的流态图像。识别不同进出水方式下的"死区"分布,计算"死区"相对面积用以表征其水力效率。结果表明:(1)进出水方式为中进上出和下进上出时,水力效率相对较高;(2)水力分布散度会对水力效率造成较大影响;(3)相比有效体积比,采用水力学效能所得到的排序结果更能代表水平潜流人工湿地的实际水力效率;(4)出水口位置对水平潜流人工湿地"死区"分布和面积有较大影响,在实际水平潜流人工湿地的设计中,出水口位置设置在上部、转角处设计为圆角将有助于减小"死区"面积、提高水力效率,有利于发挥人工湿地最大除污效果。

By conducting NaC1 tracer tests,different hydraulic residence time distribution （RTD） density curves of horizontal subsurface flow constructed wetlands with 9 inlet-outlet configurations were obtained respectively. The hydraulic parameters such as nominal retention time,mean retention time and peak retention time were calculated, and hydraulic efficiencies of constructed wetlands with different inlet-outlet configuration were calculated based on correla- tions among different retention times. Meanwhile, visualization tests of different inlet-outlet configuration were per- formed by using dyestuff. High contrast ratio images were processed by MATLAB software and the distribution of dead zones were acquired. The area of dead zones was calculated to characterize hydraulic efficiency of constructed wetland. Results showed that hydraulic efficiencies were relative higher when inlet-outlet configurations were middle inlet-top outlet and bottom inlet-top outlet. Hydraulic distribution divergence values had great impacts on hydraulic efficiency. Compared with effective volume ratio, hydraulic efficiencies were more representative in real horizontal sub- surface flow constructed wetlands. Outlet location bad great impact on distribution and area of dead zones. In the de- sign of real horizontal subsurface flow constructed wetlands, it＇s better to make the outlet location at top and make the corner rounded, which may contribute to decrease the dead zone area, increase the hydraulic efficiency and ensure the performance of constructed wetlands.