Rain brings a little coolness. However, the sharp increase in drainage has brought a severe test to the city's sewage treatment. For a long time, many old urban areas were facing problems such as incomplete diversion of rain and sewage, serious leakage of municipal sewage in dry season, and hard control of non-point source pollution in rainy season.
 
Before 2018, the Guanlan River Basin also faced a similar test. There was a gap of at least hundreds of thousands of cubic meters of sewage treatment in the main stream of Guanlan River every day. Due to the large amount of historical debts in the construction of upstream drainage pipe network, a large amount of municipal sewage flows into the sewage interception box culvert.
 
The Guanlan estuary storage pond has become the last treatment barrier in the Guanlan River basin, and its effluent quality directly affects whether the Qiping section met the standard or not. Before the upgrading and transformation, its sewage treatment capacity was far from the requirements. In 2018, the municipal government proposed a key control project for the water quality of the Qiping section.


 
RPIR technology has the characteristics of fast construction period, less land occupation, water volume change coefficient of more than 2 times, cost-effective. It was adopted and applied by the general contractor. And a high-standard and highly flexible management model of "regulating storage tank + municipal sewage linkage treatment" was established. It has both sewage treatment and rainwater storage and treatment functions in the early rainy season.
This avoids the problem of microorganisms not being able to survive due to the lack of water available in rainwater storage tanks during dry seasons.
 
During the dry season, approximately 150,000 tons of leaked sewage would be treated per day, and the effluent should comply with quasi-surface Class IV standards. The water increases significantly during the rainy season, reaching about 250,000 tons/day, and the water output complies with the quasi-surface Class V standard. It only took 133 days from winning the bid for this project to reaching water supply and production standards.
 
The first storage tank with biochemical treatment function and meeting surface Class IV emission standards was also built. It provided a guarantee for the long-term stable water quality of the Qiping section to meet the standards.
 
Today, when we walk on both sides of the Guanlan River, the green grass is accompanied by the fragrance of the earth, and the flowers reveal the pleasant fragrance. The flowers are beautiful, the wind is gentle, and the dreams are round, have you heard the sound coming from the breeze?