Clarification

This process consists of removing impurities such as particles, sediments, oils, organics and undesirable colour from the water to make it clear. It can also include sub processes like DAF and filtration, but will usually start with a screening process then chemical treatment like coagulation or flocculation

First step Screening
This is the first line of defense where large particles or foreign matter is screened out through a series of progressively finer screens.

Coarse 40 and above spacing
Medium 10 to 40mm spacing
Fine 10mm for spacing

These screens can be manually cleaned or automatically cleaned, automation is key for high flow times

Second step
Coagulation – flocculation
The three main types of particulate are classified into:

Suspended solids
Colloidal particles (smaller then 1 micron)
Dissolved substances (less than several nanometers)

Coagulation and Flocculation help to remove the Suspended solids and colloidal particles. Coagulation in particular is the destabilization of Colloidal particles, this is achieved through chemical compounds called Coagulant
Flocculation is process where colloids particles come out of suspension to form floc or flakes which can then be settled. additional reagents can be added called flocculant to promote this process. These polymers increase floc size by charged site binding and by molecular bridging.

Third step
The floc created by step two must now be removed in order to further clarify the water. The process of Flotation or Sedimentation this is achieved through mechanical flotation or DAF (Dissolved air flotation).
The DAF process involves feeding pressurized air into the flotation tank where the floc becomes bound to the very fine micro bubbles, bring the floc to the surface where it is then removed. this process can vary but the principle remains the same

Fourth Step
Fine filtrate is finally done in order to ensure Suspended solids, Colloidal particles, Dissolved substances are within desirable limits.

​Clarification

Clarification