植草沟净化地表径流运行条件优化

设计了黑麦草沟和天堂草沟两类植草沟，采用正交实验的方法研究了水力负荷、草高、水深等3个因素对植草沟净化地表径流的影响，以探索植草沟最佳运行条件。结果表明，各因素的影响大小依次为：水力负荷 > 草高 > 水深。黑麦草沟和天堂草沟的最佳运行条件相同，均为水力负荷0.5 m3·（m2·d）-1，草高15 cm，水深4 cm。在最佳运行条件下，黑麦草沟对地表径流中COD、TSS、TN、TDN、NH3-N、TP、TDP的去除率分别为，59.76%±6.52%、81.77%±13.89%、32.56%±15.34%、28.31%±16.56%、23.59%±15.53%、71.66%±12.68%、63.01%±12.8%，天堂草沟分别为，53.2%±5.57%、76.88%±11.99%、24.22%±9.85%、17.75%±6.6%、19.87%±11.69%、69.17%±11.17%、62.48%±13.04%。黑麦草沟在净化地表径流污染物方面整体优于天堂草沟，黑麦草更适宜在植草沟中使用。

Optimum operating conditions of grassed swales to purify the surface runoff

An orthogonal experiment was designed to study the effects of hydraulic load, grass height, and water depth on the purification efficiency of surface runoff by ryegrass swale and tifway bermuda grass swale, with the aim of obtaining the optimum operating conditions. The results show the degree of these effects in the order hydraulic load > grass height > water depth. For both ryegrass swale and tifway bermuda grass swale, the best hydraulic load is 0.5 m3·(m2·d)-1, grass height is 15 cm, and water depth is 4 cm. In the optimum operating conditions, the removal efficiencies for COD, TSS, TN, TDN, NH3-N, TP, and TDP of ryegrass swale are 59.76%±6.52%, 81.77%±13.89%, 32.56%±15.34%, 28.31%±16.56%, 23.59%±15.53%, 71.66%±12.68%, and 63.01%±12.8%, respectively. As regards the tifway bermuda grass swale, these are 53.2%±5.57%, 76.88%±11.99%, 24.22%±9.85%, 17.75%±6.6%, 19.87%±11.69%, 69.17%±11.17%, and 62.48%±13.04%, respectively. In conclusion, the ryegrass swale was found superior to the tifway bermuda grass swale for the purification of surface runoff.