Features:
The first generation is the direct-discharge combined drainage system: before the end of 1980s, it was basically the first generation of direct-discharge combined drainage system, with industrial wastewater, domestic sewage and initial rainwater directly discharged, and the natural water body was seriously polluted;
The second generation is interception combined system: in order to solve the problem of direct sewage discharge, sewage treatment plants have been built on a large scale since the end of 1980 s, and interception wells have been added to intercept dry sewage to the sewage treatment plants; However, in rainy season, a large amount of rainwater mixed sewage overflows from the discharge port at the end of the confluence pipe, polluting the natural water body, which is the second generation of intercepting confluence drainage system;
The third generation is the rain and sewage diversion system: one pipe can't solve the problem, so we thought of building two pipes, that is, the rain is discharged into the natural water body through the rain pipe, and the sewage enters the sewage treatment plant through the sewage pipe to realize the rain and sewage diversion. At the turn of the century, new roads and urban areas began to implement the third generation rain and sewage diversion drainage system. However, this drainage system also has two problems. First, there are staggered mixed pipes, where sewage enters the rainwater pipe or rainwater enters the sewage pipe; Second, rain and sewage diversion can't solve the problem of non-point source pollution. When it rains, the ground garbage (such as garbage transfer stations, restaurants, auto repair and agricultural products) will be brought into rivers, lakes and seas through rainwater pipelines after the initial rainwater washes the atmosphere and the ground, resulting in non-point source pollution. Therefore, the rain and sewage diversion system can not completely block pollution.
The fourth generation drainage system is sewage diversion: it is an upgrade on the basis of the existing drainage pipe network, and its core is intelligent diversion, accurate sewage interception, peak regulation and storage, and intelligent water affairs to realize real sewage diversion. On the one hand, it improves the influent concentration of the sewage treatment plant and ensures the efficient operation of the sewage treatment plant; On the other hand, the pollutants entering the natural water body are controlled within the allowable range that the natural water body itself can absorb, and the long-term cleaning of the natural water body is realized.