As a large amount of rainwater is intercepted, which affects the natural circulation and landscape water level of the river course, it is estimated that the sewage volume of the sewage collection system in the north of the city in the dry season is about 300000 tons / day. Considering the factors of closure multiple, the sewage volume in the rainy season is about 630000 tons / day, so the bigger problem is exposed, that is, with the improvement of the sewage collection system, it is bound to fall into the insufficient design capacity of the newly constructed sewage treatment plant There is a dilemma, and the possibility of building another WWTP within the established sewage collection range is almost zero