Explain Rapid Mixing Tank
- For the chemical reactions to occur, the chemicals must be mixed with water
- for both coagulation and softening we need mixing of chemical with water
- Mixing or rapid mixing is the process in which chemicals are quickly and uniformly dispersed in water (instantaneously)
- for coagulation and softening processes precipitates form during the mixing
- the precipitates formed must be brought into contact with one another and colloids so that they can agglomerate and form larger particles called flocs - this process is called flocculation and is accomplished by slow, gentle mixing (rapid mixing may break up the flocs)
- Degree of mixing is measured by velocity gradient G (amount of shear taking place). Higher the G, the more violent the mixing
Design Criteria
Rapid Mix
Volume = Flow rate (Q)*detention time
Detention is in the order of seconds 30-120 seconds
Mixing basin is typically a cube