生态透水带去除洱海流域生活污水氮的效果

洱海流域部分村镇生活污水缺乏系统收集及管理而直排，对洱海水质造成了显著不利影响。通过构建生态透水带，旨在摸清其去除分散式生活污水中氮的能力、机理、植物种类对除氮的影响及透水带最佳宽度。构建了4条规格为4 m×1 m×0.5 m的生态透水带，均匀敷设厚0.3 m，粒径10~18 mm（平均14 mm）的碎石。其中3条分别种植本地植被芦苇、水葱和香蒲，余下1条为空白带。实验周期3个月，每星期采水样1次，持续进水，水量0.3 m3·d-1，水力负荷7.5 cm·d-1，进水总氮（TN）平均浓度31.15 mg·L-1。结果表明，透水带具有很好的除氮效果，TN去除率依次为：香蒲（80.22%） > 水葱（76.98%） > 芦苇（69.23%） > 空白（63.61%），植物类型对透水带TN去除效果影响显著（P-1）、水葱（7.17 mg·L-1）、芦苇（9.58 mg·L-1）、空白（11.34 mg·L-1），均达到了城镇污水处理厂污染物排放标准的一级A标准。平均氨氮出水浓度依次为：香蒲（4.47 mg·L-1）、水葱（5.48 mg·L-1）、芦苇（8.23 mg·L-1）、空白（9.67 mg·L-1），种植植物的条带达到了城镇污水处理厂污染物排放标准的一级B标准。在TN去除率为80%时，不同透水带最佳宽度不同，香蒲（3.9 m） < 水葱（4.7 m） < 芦苇（6.3 m） < 空白（8.6 m）。

Effect of nitrogen removal by ecological permeable belts treating domestic wastewater of Erhai Lake basin

Because of the absence of sewage collection and manage system in some towns by the Erhai Lake shore, some wastewater drains off into the lake directly and further impairs the water quality of the lake. In this study, by construction of ecological permeable belt, nitrogen removal capacity for decentralized domestic sewage, nitrogen removal mechanism, effect of vegetation selection on nitrogen removal efficiency, and optimized width of the belt, are respectively investigated. Four ecological permeable belts are constructed with a size of 4 m×1 m×0.5 m, and a 0.3 m layer is set uniformly under each permeable belt with gravel whose particle size range is from 10 to 18 mm and average particle size is 14 mm. Three of the four belts are planted with Bulrush, Scripus tabernaemontani,Balamus, respectively, and the remaining belt is set as a blank controller without vegetation. The experiment lasted three months and water samples were collected once a week. The influent flow is continuous with an amount of 0.3 m3·d-1 the hydraulic load is 7.5 cm·d-1, and the mean TN concentration is 31.15 mg·L-1. The results show that ecological permeable belts could reduce the TN in ecological permeable belts effectively, the TN removal efficiency from high to low are Bulrush,Scripus tabernaemontani, cattail, and blank controller. The average TN removal rate is 80.22%, 76.98%, 69.23%, 63.61%, respectively. Effect of vegetation selection on TN removal efficiency is significant(PBulrush(6.16 mg·L-1), Scripus tabernaemontani(7.17 mg·L-1), cattail(9.58 mg·L-1), and blank controller(11.34 mg·L-1), all had achieved Discharge Standard of Pollutants Formunicipal Wastewater Treatment Plant (GB 18918-2002) the center one levels A to discharge the standard. The average ammonia concentration is Bulrush(4.47 mg·L-1), Scripus tabernaemontani(5.48 mg·L-1), cattail(8.23 mg·L-1), and blank controller(9.67 mg·L-1),except the blank controller, the other three belts had achieved the center one levels B to discharge the standard.Meanwhile, when average removal rate of TN is 80%, the optimal width is different for each belt:3.9 m for Bulrush, 4.7 m for Scripus tabernaemontani, 6.3 m for cattail, and 8.6 m for blank controller.