The pollution caused by wet weather overflow in urban drainage systems is a main factor causing blackening an odorization of urban rivers. The conventional overflow treatment based on coagulation/flocculation in terminal drainage systems requires relatively large space and long retention time demand that makes it not applicable in crowded urban drainage systems or under heavy rains. On-site coagulation/flocculation in terminal drainage pipes was proposed in this study which was aimed to transfer the coagulation/flocculation process to the inside of pipes at the terminal drainage system to save space and reduce the retention time of the coagulation/flocculation process. The optimized dose of chemicals was studied first which was 80 mg/L of coagulant and 0.8 mg/L of flocculant. Settling for only 5 min can remove most of the pollutants at 406.5 m of transmission distance. In addition, the relation of wet weather overflow rate and concentration of pollution load on the on-site coagulation/flocculation process was investigated, which indicated that high removal of pollutant was gained at a large range of flow velocity and pollutant concentration. Finally, the study confirmed electric neutralization, bridging, and net capture as the major mechanisms in this process, and further optimization was proposed. The proposed process can reduce much turbidity, chemical oxygen demand, and total phosphorous, but hardly remove soluble ammonia and organics. This work provides scientific guidance to address wet weather overflow in terminal drainage pipes.

城市排水系统中潮湿的天气溢出造成的污染是导致城市河流变黑的主要因素。在终端排水系统中基于凝结/絮凝的常规溢流处理需要相对较大的空间和较长的保留时间要求，这使其不适用于拥挤的城市排水系统或大雨天。这项研究提出了在终端排水管中进行现场混凝/絮凝的目的，旨在将凝结/絮凝过程转移到终端排水系统的管道内部，以节省空间并减少凝结/絮凝过程的保留时间。首先研究了化学药品的最佳剂量，即混凝剂80 mg / L和絮凝剂0.8 mg / L。在406处沉淀仅需5分钟即可去除大部分污染物。传输距离为5 m。此外，研究了湿润天气的溢流率与污染负荷浓度在现场混凝/絮凝过程中的关系，表明在较大的流速和浓度范围内，污染物的去除率较高。最后，研究证实了电中和，桥接和捕网是该过程的主要机理，并提出了进一步的优化措施。拟议的过程可以减少许多浊度，化学需氧量和总磷，但几乎不去除可溶性氨和有机物。这项工作为解决终端排水管中的潮湿天气溢出提供了科学指导。研究了潮湿天气溢流率与污染负荷浓度在现场混凝/絮凝过程中的关系，表明在较大的流速和浓度范围内，污染物去除率较高。最后，研究证实了电中和，桥接和捕网是该过程的主要机制，并提出了进一步的优化措施。拟议的过程可以减少许多浊度，化学需氧量和总磷，但几乎不去除可溶性氨和有机物。这项工作为解决终端排水管中的潮湿天气溢出提供了科学指导。研究了潮湿天气溢流率与污染负荷浓度在现场混凝/絮凝过程中的关系，表明在较大的流速和浓度范围内，污染物去除率较高。最后，研究证实了电中和，桥接和捕网是该过程的主要机理，并提出了进一步的优化措施。拟议的过程可以减少许多浊度，化学需氧量和总磷，但几乎不去除可溶性氨和有机物。这项工作为解决终端排水管中的潮湿天气溢出提供了科学指导。该研究证实了电中和，桥接和捕网是该过程的主要机理，并提出了进一步优化的建议。拟议的过程可以减少许多浊度，化学需氧量和总磷，但几乎不去除可溶性氨和有机物。这项工作为解决终端排水管中的潮湿天气溢出提供了科学指导。该研究证实了电中和，桥接和捕网是该过程的主要机理，并提出了进一步优化的建议。拟议的过程可以减少许多浊度，化学需氧量和总磷，但几乎不去除可溶性氨和有机物。这项工作为解决终端排水管中的潮湿天气溢出提供了科学指导。