上海市截流外排工程污水扩散影响数值研究

城市污水截流外排工程是上海市城市水环境整治的重大战略。文章以CODCr为例，数值模拟研究了上海近岸水域东、南、西三大截流外排干线不同排污方案下污染物的输移扩散规律。结果表明，长江口的水动力条件有利于污水的稀释扩散；在现状排污条件下，无论洪枯季，引起的环境水体污染物CODCr浓度增量均不大，能够满足长江口水环境容量的要求；对于规划排放量的污水，预处理和一级处理条件下引起的环境水体污染物CODCr，浓度增量较为显著，对周围敏感目标的影响也比较大；二级处理条件下所引起的污染浓度增量比较小，对水环境的影响相对较小。因此，在规划城市污水外排工程时，建议必须近期和远期相结合，合理充分利用水体自净能力。

Numerical simulation of transport and diffusion of Shanghai municipal sewage outfalls

The project of municipal sewage discharge is the great stratagem of Shanghai water environmental renovation. In this paper, a 2-D hydrodynamic and water quality numerical model in the region of offshore water near Shanghai is established. Taking CODer as example, a comprehensive analysis on the three trunks of the east, south and west sewage outfalls of pollutant transport and its effect on the Yangtse Estuary water environment has been developed under some kinds of dynamic factors and different sewage discharge schemes. The simulation results indicates that under the condition of status quo gross discharge, the increment of pollutant CODCr concentration is not high whenever flood season or dry season, so it can meet with the environmental capacity of Yangtse Estuary. For the three trunks of sewage outfalls engineering, in the term of pretreatment and firstly level disposal, the concentration increment of water environment pollutant CODCr is quite notable under the condition of layout gross discharge, so it has a relatively great effect on its nearby sensitive objects. While in the term of the secondly level disposal, the concentration increment is smaller. In conclusion, in ordre to make the best of Yangtse Estuary water environmental capacity, it should be taken into account in the near further combining with a specified future data during the time of the layout of Shanghai sewage project.