Influence of rainwater mixing rate on design scale of sewage treatment plant in coastal area

Taking a sewage treatment plant in Taizhou, a coastal city, as an example, based on the triangle method, the response relationship between rainwater mixing and water quality and quantity of sewage treatment plant was analyzed. The influence of rainwater mixing rate on the design scale of sewage treatment plant was discussed. The results show that the influent water quality of sewage treatment plant in coastal area is greatly affected by rainfall, and the actual influent water quality is less than the design value due to the rainwater mixing. The effect of sewage treatment plants in coastal areas is poor, and the average value of pollution load reduction rate is far lower than the national average value. In case of light rain, the pollution load reduction rate of sewage treatment plant in coastal area is the highest, and the pollution load reduction rate decreases with the increase of rainfall intensity. When the sewage treatment plant in coastal area operates at full load, the treatment rate of sewage volume is relatively low, which is 60% -70%. The actual water inflow of sewage treatment plant in coastal area is far greater than the design value, and the design scale of water volume should be multiplied by 1.4 correction coefficient. © 2020, Editorial Board of Water Resources Protection. All rights reserved.