PWDL多吸头排污泵生活污水和工业废水经排水管渠系统汇集由各区城排水泵站将污水抽送回污水处理厂，逆向的循环过程。实际上，在排水管聚系统中使用泵站的场合是相当多的。除抽送污水和工业废水的泵站外，还有专门抽送雨水的泵站。也有仅用来抽送城市地势低洼区防洪排涝的区域性泵站。在污水处理厂内，往往从沉淀池把新鲜污泥抽送到污泥消化池，从沉砂池中排除沉渣，从二次沉淀池中提送回流活性污泥等，都要用各种不同类型的泵和泵站来保证运行的水资源是基础自然资源，是生态环境的控制性因素之一。正如本书前言中所述，在水资源合理开采、利用和共享的大政方针下，全国出现了多个跨区、路市的长距离、大流量的输配水系统工程的建设。在这些大型的调水工程中，泵站的建设和运行管理通常是起很重要的角色。诸如“引滦人津”工程，是-项较大规模的跨流域的调水工程。该工程全长234km,全年引水量达10亿余立方米，全部工程中修建了4座大型泵站，分别采用了多台叶片可调型的大型轴流泵和高压离心泵进行抽升工作。除此以外，在农田灌溉、防洪排涝等方面，泵站经常作为一个独立的构筑物而服务于各项事业。特别是随着社会主义农业的现代化，在农田基本建设中、在抽升黄河水引向西北高原的大型灌溉工程中都需建造很多大型、巨大型的泵站。在这方面有大流量、低扬程的轴流泵站，也有大流量、高扬程的离心泵站。目前，在我国西北地区抽升黄河水进行高原灌溉的工程中，已建成的大型泵站的单泵扬程一般均在70~ 150m以上，有时多座泵站“串联”作，组成梯级泵站群，工程规模是十分壮观的从经济的角度来看，城市供水企业一般都是用电大户。在整个给水工程的用电量中。95% -98%的电量是用来维持泵的运转，其他2%一5%用在制水过程中的辅助设备上(如电动阀、排污泵、真空泵、机修及照明等)。以一般城镇水厂而言，泵站消耗的电费，通常占自来水制水成本的40%—70%，甚至更多。就全国泵机组的电能消耗而言，它占全国电能总耗的219%以上。因此，通过科学调度，提高机泵设备的运行效率;采用调速电机，扩大泵机组的高效工作范围;对役龄过长、设备陈旧的机泵，及时采取更新改造等措施，都是合理降低泵站电耗的重要途径。消止回阀等方式均能达到良好的节电效果。

The domestic sewage and industrial sewage from PWDL multi-suction sewage pump are collected through the drainage pipe system and pumped back to the sewage treatment plant by the sewage pump stations in each district and city, in a reverse circulation process. In fact, there are quite a number of occasions in which pumping stations are used in drainage systems. In addition to pumping stations for pumping sewage and industrial wastewater, there are also pumping stations for pumping rainwater. There are also regional pumping stations that are only used for pumping flood control and drainage in low-lying urban areas. In the sewage treatment plant, fresh sludge is often pumped from the sedimentation tank to the sludge digestion tank, sediment is removed from the sedimentation tank, and reflux activated sludge is pumped from the secondary sedimentation tank. Various types of pumps and pumping stations are used to ensure that the running water resources are basic natural resources and one of the controlling factors of the ecological environment. As stated in the preface of this book, under the general policy of rational exploitation, utilization and sharing of water resources, there have been many long-distance and large-flow water transmission and distribution system projects across regions and cities across the country. In these large-scale water transfer projects, the construction and operation management of pump stations usually play a very important role. For example, the project of "diverting water from Luan River to Tianjin" is a large-scale inter-basin water transfer project. The total length of the project is 234km, and the annual water diversion volume is more than 1 billion cubic meters. Four large pumping stations have been built in the whole project, and several large axial flow pumps with adjustable blades and high-pressure centrifugal pumps have been used for pumping. In addition, in the fields of farmland irrigation, flood control and drainage, the pump station often serves various undertakings as an independent structure. Especially with the modernization of socialist agriculture, many large and huge pumping stations need to be built in the construction of farmland infrastructure and in the large-scale irrigation projects that pump water from the Yellow River to the northwest plateau. In this respect, there are axial flow pump stations with large flow and low head, and centrifugal pump stations with large flow and high head. At present, in the project of pumping water from the Yellow River for plateau irrigation in the northwest of China, the single pump head of the built large pumping stations is generally more than 70~150 m, and sometimes several pumping stations are "in series" to form a cascade pumping station group. The project scale is very spectacular. From the economic point of view, urban water supply enterprises are generally large consumers of electricity. In the electricity consumption of the whole water supply project. 95% - 98% of the electricity is used to maintain the operation of the pump, and the other 2% - 5% is used in the auxiliary equipment (such as electric valve, sewage pump, vacuum pump, machine repair and lighting) in the water production process. For general urban water plants, the electricity consumption of pump stations usually accounts for 40% - 70% of the cost of water production from tap water, or even more. As far as the electric energy consumption of pump units in the country is concerned, it accounts for more than 219% of the total electric energy consumption in the country. Therefore, improve the operation efficiency of pump equipment through scientific scheduling; Adopt speed regulating motor to expand the efficient working range of pump unit; It is an important way to reasonably reduce the power consumption of the pump station to take timely measures such as updating and transforming the pump with long service life and outdated equipment. Fire check valve and other methods can achieve good power saving effect.