WTO Coagulation and Flocculation 3

Question 1

Cationic polymers work as coagulant aids primarily by:

Accepted Answer

Neutralizing the negative surface charge of particles

Answer

Cationic (positively charged) polymers neutralize the negative charge on suspended particles, reducing repulsion and promoting aggregation.

Question 2

What does a 'Gt' value represent in flocculation design?

Accepted Answer

The product of velocity gradient and detention time, indicating total mixing energy

Answer

Gt (dimensionless camp number) is the product of velocity gradient G and detention time t, representing the total collision opportunity for particles in a flocculation basin.

Question 3

Which coagulant is most commonly used in conventional US water treatment plants?

Accepted Answer

Alum (aluminum sulfate)

Answer

Alum (aluminum sulfate) is the most widely used coagulant in US water treatment due to its effectiveness, availability, and low cost.

Question 4

High natural organic matter (NOM) in source water affects coagulation by:

Accepted Answer

Increasing the optimal coagulant dose needed

Answer

NOM consumes coagulant through reactions with organic molecules, increasing the required dose to achieve effective particle destabilization.

Question 5

In a tapered flocculation basin, mixing energy is designed to:

Accepted Answer

Decrease from inlet to outlet to allow gentle floc growth

Answer

Tapered flocculation decreases mixing intensity from inlet to outlet so that initially formed floc particles grow gently without being sheared apart.

(WTO) Water Treatment Operator Certification Practice Test

(WTO) Water Treatment Operator Certification Practice Test

WTO Coagulation and Flocculation 3