Class B Practice Exam Questions And

Surface Water Treatment Operator Class B Practice Exam Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

1. The primary purpose of coagulation in water treatment is to:

• Remove dissolved minerals
• Destabilize and aggregate suspended particles
• Kill bacteria
• Adjust pH

Rationale:

Coagulation is used to destabilize colloidal and suspended particles so they can aggregate into larger particles (flocs) that can be removed by sedimentation or filtration. 1 / 4

• Which coagulant is commonly used in surface water treatment?
• Sodium bicarbonate
• Aluminum sulfate (alum)
• Calcium hydroxide
• Chlorine

Rationale:

Aluminum sulfate (alum) is widely used as a coagulant to form flocs from suspended solids in surface water treatment.

• What is the main purpose of flocculation?
• Chlorinate water
• Adjust pH
• Promote aggregation of small particles into larger flocs
• Remove dissolved iron

Rationale:

Flocculation gently mixes water to encourage the small destabilized particles to collide and form larger flocs suitable for sedimentation.

4. Sedimentation is primarily used to:

• Remove dissolved organics
• Remove settleable solids
• Disinfect water
• Adjust alkalinity 2 / 4

Rationale:

Sedimentation allows larger particles (flocs) to settle out of the water by gravity, reducing turbidity before filtration.

5. The main function of rapid sand filters is to:

• Add coagulant
• Remove suspended solids and turbidity
• Disinfect water
• Remove hardness

Rationale:

Rapid sand filters remove suspended solids that remain after sedimentation, improving water clarity and quality.

6. The term "turbidity" refers to:

• pH level
• Hardness
• Cloudiness or suspended particles in water
• Chlorine residual

Rationale:

Turbidity is a measure of water clarity caused by suspended particles such as silt, clay, or organic matter.

• Which of the following is a key parameter to monitor for coagulation

control?

• Temperature 3 / 4

• pH
• Chlorine residual
• Conductivity

Rationale:

pH affects the solubility of the coagulant and the formation of flocs; improper pH can reduce coagulation efficiency.

8. Lime is added in water treatment to:

• Remove bacteria
• Adjust pH and alkalinity
• Act as a coagulant
• Remove chlorine

Rationale:

Lime (calcium hydroxide) is used to raise pH, adjust alkalinity, and aid in softening water.

9. A common method to disinfect water is:

• Coagulation
• Flocculation
• Chlorination
• Sedimentation

Rationale:

Chlorination is widely used to kill pathogenic microorganisms and provide a residual disinfectant in the distribution system.

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