The composition of sewage in the service area is complex, including ordinary domestic wastewater, oily wastewater from gas stations, restaurants and garages, laundry wastewater, etc. The main pollution factors of its wastewater are oil, COD, BOD, SS, etc. The sewer outlet in the general service area has the following characteristics:

1, with many pollution points and small treatment scale. In general, the water consumption of the unilateral service area is10-100m3/h;

2. Sewage mainly comes from public toilets and cleaning, with high nitrogen and phosphorus content;

3. Catering wastewater accounts for a large proportion, and there are oily and lipid pollutants in parking areas and squares, gas stations and car wash wastewater;

4. The sewage is uneven, and the treatment difficulty is higher than that of typical domestic sewage. In addition, in the specific sewage treatment, it is found that the sewage volume in the service area changes obviously with the seasons, so it needs to be adjusted and changed according to the seasonal changes in the specific sewage treatment.