天目山隧道进口段毗邻“新安江—富春江—千岛湖”国家级风景名胜区，为避免隧道施工废水影响当地生态环境和饮水安全，对其特征进行分析，发现废水中悬浮物（SS）和酸碱度（pH）超标，且含有重金属。部分水样中汞（Hg）和镍（Ni）超标（其中Hg的超标频次较高），其他重金属未超标，废水中出现重金属与地质有关。采用“初沉+混凝+沉淀+过滤”工艺处理废水，初沉主要去除大颗粒悬浮物，混凝、沉淀主要去除细颗粒物和重金属。结果表明： 处理后的废水各指标均满足排放要求，处理成本为0.51元/m3，经济性较好。

The entrance of Tianmushan Tunnel is adjacent to the national scenic area of “Xin’an RiverFuchun RiverQiandao Lake”. The protection of the safety of local ecological environment and drinking water is very important. As a result, the characteristics of construction wastewater of Tinmushan Tunnel are analyzed; the results show that the suspended solids (SS) and power of hydrogen (pH) in wastewater exceed the limit. The heavy metals related to the engineering geology are detected in the wastewater, which do not exceed the limit except mercury (Hg) and nickel (Ni) in some of water samples. The wastewater treatment method of “primary setting + coagulation + sediment + filtration” is adopted. The suspended solids with large particle size can be removed by primary setting process; and the fine particulate matter and the heavy metals can be removed by coagulation and sediment process. The application results show that the quality of construction wastewater after treatment can meet relevant requirements; meanwhile, the treatment cost of the wastewater per cubic meter is RMB 0.51, so as to show beffer economical benefit.