It is flash-mixed into the raw river water before it flows into the first sedimentation basin. The polymer effectively attracts and enmeshes negatively charged turbidity particles in raw river water and causes them to settle. A large blow-down located at the center of polymer sedimentation basin is activated at timed intervals to dispel settled and collected solids. The level of suspended material or turbidity is reduced significantly by this process. Aerial construction view of covered disinfection contact basin.
Interior baffles provide precision chemical application.
The partially processed water then flows by gravity to the disinfection contact basin. Chlorine is added at the entry of this basin to destroy any bacteria or viruses that may be present. Ammonia is subsequently added at a specified entry point after chlorine addition to form the secondary distribution disinfectant, chloramine. A series of baffles in the disinfection contact basin provide effective contact and reaction time to ensure that the destruction of pathogens is complete. The controlled application of chlorine and ammonia in the absence of sunlight reduces the level of disinfection by-products below regulatory requirements.