AWWA AWWA Water Treatment Processes

Question 1

In conventional water treatment, what is the correct sequence of primary treatment processes?

Accepted Answer

Coagulation → Flocculation → Sedimentation → Filtration

Answer

Disinfection → Coagulation → Sedimentation → Filtration

Answer

Filtration → Coagulation → Sedimentation → Disinfection

Answer

Sedimentation → Coagulation → Flocculation → Filtration

Question 2

Which coagulant is most commonly used in US water treatment plants for turbidity removal per AWWA practices?

Accepted Answer

Aluminum sulfate (alum)

Answer

Potassium permanganate

Answer

Sodium hypochlorite

Answer

Ferrous sulfate

Question 3

What is the purpose of the rapid mix (flash mix) stage in a water treatment plant?

Accepted Answer

To achieve thorough dispersion of coagulant chemicals throughout the water

Answer

To remove dissolved gases

Answer

To accelerate sedimentation

Answer

To neutralize disinfection byproducts

Question 4

Per AWWA guidelines, what CT value concept is used to evaluate disinfection effectiveness?

Accepted Answer

Disinfectant concentration (C) times contact time (T)

Answer

Chlorine concentration times turbidity

Answer

Chemical cost times treatment volume

Answer

Coagulant dose times flocculation time

Question 5

What is the primary purpose of lime softening in water treatment?

Accepted Answer

To remove hardness-causing calcium and magnesium ions

Answer

To reduce turbidity through coagulation

Answer

To oxidize iron and manganese

Answer

To adjust pH for corrosion control

Question 6

Which AWWA manual covers water treatment plant design?

Accepted Answer

AWWA M46

Answer

AWWA M1

Answer

AWWA M11

Answer

AWWA M50