State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, China.
State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China; Key Laboratory of Yangtze River Water Environment, Ministry of Education, Tongji University, Shanghai, 200092, China.
Water Res. 2020 May 15;175:115689. doi: 10.1016/j.watres.2020.115689. Epub 2020 Mar 6.
Groundwater infiltration into sanitary sewers increases hydraulic loadings of sewage collection systems and threatens wastewater treatment efficiency. However, cost-effective approach to quantify this important process still needs to be improved in order to better manage this common issue. This paper presents a method for determining the origin and amount of groundwater entering the urban sewer system. On a catchment scale, by measuring and tracking a chemical tracer (i.e., artificial sweetener acesulfame) in the urban sewers, the magnitude of daily groundwater flows in each sub-catchment could be quantified based on a Monte Carlo chemical mass balance approach. For the study site, 7.9% of the sewer length contributed 58% of the total groundwater infiltration. In the identified high-risk sub-catchment, groundwater sources and their spatial-temporal flows could be further pinpointed and elucidated by physically based numerical self-optimization model using microbial genetic algorithm method, which was verified by on-site sewer flow measurements, as well as time-series tracer concentration patterns at the terminal outlet. It was found that the diurnal variations of groundwater seepage into sewer network was linked to the in-pipe water level associated with sewage pumps operation mode, demonstrating the importance of in-pipe water level regulation in controlling groundwater infiltration. Compared with traditional visual inspection or direct flow measurement methods, the proposed approach exhibits distinct advantages in determining groundwater sources and flows in large sewer systems.
地下水渗入污水管道会增加污水收集系统的水力负荷，威胁废水处理效率。然而，为了更好地管理这一常见问题，仍需要改进一种经济有效的方法来量化这一重要过程。本文提出了一种确定地下水进入城市污水系统的来源和数量的方法。在集水区尺度上，通过在城市污水中测量和追踪一种化学示踪剂（即人工甜味剂乙酰磺胺酸钾），可以基于蒙特卡罗化学质量平衡方法来量化每个子流域的每日地下水流量。对于研究地点，7.9%的污水管长度贡献了 58%的总地下水渗入量。在确定的高风险子流域中，可以通过基于物理的数值自优化模型（使用微生物遗传算法方法）进一步确定和阐明地下水源及其时空流动情况，并通过现场污水流量测量以及终端出口处的时间序列示踪剂浓度模式进行验证。结果发现，地下水渗入管网的日变化与与污水泵运行模式相关的管内水位有关，这表明在控制地下水渗入方面，管内水位调节非常重要。与传统的目视检查或直接流量测量方法相比，该方法在确定大型污水系统中的地下水来源和流量方面具有明显的优势。
