FDEP WATER TREATMENT CLASS C OPERATOR CERTIFICATION
EXAM
210 ORIGINAL PRACTICE QUESTIONS, ANSWERS &
RATIONALES — 2026–2027
SECTION 1 — WATER TREATMENT PROCESSES
Questions 1–15
1. What is the primary purpose of coagulation in conventional
drinking-water treatment?
A. To disinfect finished water
B. To destabilize suspended and colloidal particles
C. To remove dissolved oxygen
D. To increase water hardness
Correct Answer: B
Rationale: Coagulation destabilizes small particles so they can collide
and form larger particles during subsequent flocculation.
2. What is the primary purpose of flocculation?
A. Rapidly mix disinfectant into water
B. Increase water temperature
C. Gently mix destabilized particles so they form larger flocs
D. Remove dissolved salts
,Correct Answer: C
Rationale: Gentle mixing encourages particle collisions and growth of
settleable flocs.
3. What is the main purpose of sedimentation?
A. Allow heavier floc particles to settle by gravity
B. Add alkalinity
C. Destroy microorganisms
D. Increase turbidity
Correct Answer: A
Rationale: Sedimentation removes suspended solids by allowing
sufficiently dense particles to settle.
4. Which treatment process generally follows sedimentation in
conventional treatment?
A. Filtration
B. Raw-water pumping
C. Coagulation
D. Source-water collection
Correct Answer: A
Rationale: Filtration removes remaining suspended particles that were
not removed during coagulation, flocculation and sedimentation.
5. What is the principal purpose of disinfection?
,A. Reduce hardness
B. Control pathogenic microorganisms
C. Increase turbidity
D. Remove all dissolved minerals
Correct Answer: B
Rationale: Disinfection is used primarily to inactivate disease-causing
microorganisms.
6. Which condition generally improves sedimentation of properly
formed floc?
A. Excessive turbulence
B. Adequate detention and relatively quiescent conditions
C. Extremely high flow velocity
D. Continuous violent mixing
Correct Answer: B
Rationale: Settling requires conditions that allow particles to fall
without being resuspended.
7. What is turbidity primarily a measure of?
A. Water temperature
B. Cloudiness caused by suspended or colloidal material
C. Chlorine concentration only
D. Water hardness
Correct Answer: B
, Rationale: Turbidity results from particles that scatter or absorb light.
8. Why is rapid mixing used after a coagulant is added?
A. To distribute the chemical quickly and uniformly
B. To settle floc immediately
C. To increase bacterial growth
D. To remove hardness
Correct Answer: A
Rationale: Rapid mixing promotes uniform dispersion of the coagulant
throughout the water.
9. Excessively vigorous mixing during flocculation can:
A. Improve every floc automatically
B. Break apart developing floc
C. Eliminate all turbidity instantly
D. Increase sedimentation depth
Correct Answer: B
Rationale: Flocculation requires controlled gentle mixing; excessive
shear can break fragile floc.
10. What is a major function of a filter in a conventional plant?
A. Remove remaining particulate material
B. Add pathogens
EXAM
210 ORIGINAL PRACTICE QUESTIONS, ANSWERS &
RATIONALES — 2026–2027
SECTION 1 — WATER TREATMENT PROCESSES
Questions 1–15
1. What is the primary purpose of coagulation in conventional
drinking-water treatment?
A. To disinfect finished water
B. To destabilize suspended and colloidal particles
C. To remove dissolved oxygen
D. To increase water hardness
Correct Answer: B
Rationale: Coagulation destabilizes small particles so they can collide
and form larger particles during subsequent flocculation.
2. What is the primary purpose of flocculation?
A. Rapidly mix disinfectant into water
B. Increase water temperature
C. Gently mix destabilized particles so they form larger flocs
D. Remove dissolved salts
,Correct Answer: C
Rationale: Gentle mixing encourages particle collisions and growth of
settleable flocs.
3. What is the main purpose of sedimentation?
A. Allow heavier floc particles to settle by gravity
B. Add alkalinity
C. Destroy microorganisms
D. Increase turbidity
Correct Answer: A
Rationale: Sedimentation removes suspended solids by allowing
sufficiently dense particles to settle.
4. Which treatment process generally follows sedimentation in
conventional treatment?
A. Filtration
B. Raw-water pumping
C. Coagulation
D. Source-water collection
Correct Answer: A
Rationale: Filtration removes remaining suspended particles that were
not removed during coagulation, flocculation and sedimentation.
5. What is the principal purpose of disinfection?
,A. Reduce hardness
B. Control pathogenic microorganisms
C. Increase turbidity
D. Remove all dissolved minerals
Correct Answer: B
Rationale: Disinfection is used primarily to inactivate disease-causing
microorganisms.
6. Which condition generally improves sedimentation of properly
formed floc?
A. Excessive turbulence
B. Adequate detention and relatively quiescent conditions
C. Extremely high flow velocity
D. Continuous violent mixing
Correct Answer: B
Rationale: Settling requires conditions that allow particles to fall
without being resuspended.
7. What is turbidity primarily a measure of?
A. Water temperature
B. Cloudiness caused by suspended or colloidal material
C. Chlorine concentration only
D. Water hardness
Correct Answer: B
, Rationale: Turbidity results from particles that scatter or absorb light.
8. Why is rapid mixing used after a coagulant is added?
A. To distribute the chemical quickly and uniformly
B. To settle floc immediately
C. To increase bacterial growth
D. To remove hardness
Correct Answer: A
Rationale: Rapid mixing promotes uniform dispersion of the coagulant
throughout the water.
9. Excessively vigorous mixing during flocculation can:
A. Improve every floc automatically
B. Break apart developing floc
C. Eliminate all turbidity instantly
D. Increase sedimentation depth
Correct Answer: B
Rationale: Flocculation requires controlled gentle mixing; excessive
shear can break fragile floc.
10. What is a major function of a filter in a conventional plant?
A. Remove remaining particulate material
B. Add pathogens
