What effect does raw water temperature approaching the freezing point have on coagulation and flocculation processes?

When raw water temperature approaches freezing, it can significantly affect the processes of coagulation and flocculation. At lower temperatures, the kinetic energy of particles decreases. This leads to reduced movement and interaction among particles, which can hinder the effective aggregation needed for flocculation to occur.

Coagulation relies on the addition of chemicals to destabilize colloidal particles, encouraging them to stick together and form larger aggregates, or floc. In colder conditions, the reduced particle motion means that the formation of floc happens more slowly. Additionally, the viscosity of water increases as temperature decreases, further impeding the settling rate of the floc. Consequently, less efficient floc formation and slower settling rates can lead to challenges in the treatment process, making it critical for operators to account for these temperature effects when designing and managing water treatment systems.