Examination Practice Test Questions

Water Works Operator Class B Licensing Examination Practice Test Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

Subjects Included: Treatment, Distribution, Safety, Regulations, Chemistry,

Math (conceptual), Operations, Sampling, Maintenance, Hydraulics

• What is the primary purpose of coagulation in water treatment?
• Remove dissolved gases
• Reduce hardness
• Destabilize suspended particles
• Adjust pH

Coagulation destabilizes colloidal particles so they can clump and be removed during flocculation and sedimentation. 1 / 3

• Which chemical is most commonly used as a coagulant?
• Sodium fluoride
• Aluminum sulfate
• Chlorine dioxide
• Potassium permanganate

Alum (aluminum sulfate) is the most widely used coagulant in conventional treatment.

• What is the typical pH range for effective alum coagulation?

A. 3–4

B. 5–6

C. 6–7

D. 9–10

Alum works best in a slightly acidic to neutral pH range, typically 6– 7.

4. A rapid mix basin is used primarily to:

• Remove turbidity
• Settle particles
• Evenly disperse coagulant
• Support biological growth

Rapid mixing ensures the coagulant disperses instantly, allowing destabilization to occur.

5. The purpose of flocculation is to:

• Oxidize metals 2 / 3

• Disinfect pathogens
• Form larger, settleable particles
• Reduce alkalinity

Flocculation gently mixes water to grow floc that settles in sedimentation basins.

• What is the typical detention time for flocculation?
• 5–10 minutes
• 20–45 minutes
• 2–3 hours
• 5–6 hours

Flocculation requires moderate mixing for 20–45 minutes to allow floc to grow.

• Which parameter is most important to monitor in flocculation basins?
• Temperature
• Turbidity
• Fluoride
• Chlorine residual

Turbidity indicates whether flocculation is forming proper floc.

8. Sedimentation primarily removes:

• Dissolved solids
• Gases
• Hardness minerals
• / 3