FLORIDA ENVIRONMENTAL OPERATOR EXAM
LEVEL IV PRACTICE QUESTIONS WITH
CORRECT ANSWERS (VERIFIED ANSWERS)
PLUS RATIONALES 2026 Q&A | INSTANT
DOWNLOAD PDF:
1. Which of the following is the primary purpose of a water
treatment plant?
A. Increase water pH
B. Remove pathogens
C. Add nutrients
D. Increase water temperature
B. Remove pathogens
Rationale: The main goal of water treatment is to make water
safe by removing disease-causing organisms.
2. What is the recommended residual chlorine level in drinking
water distribution systems?
A. 0.1–0.5 mg/L
B. 0.2–1.0 mg/L
C. 1.0–2.0 mg/L
D. 2.0–3.0 mg/L
B. 0.2–1.0 mg/L
Rationale: Maintaining 0.2–1.0 mg/L ensures disinfection while
minimizing taste and odor issues.
3. In wastewater treatment, the purpose of primary clarification is
to:
, A. Remove nutrients
B. Remove settleable solids
C. Disinfect effluent
D. Reduce BOD biologically
B. Remove settleable solids
Rationale: Primary clarifiers allow heavy solids to settle, reducing
the load on subsequent treatment processes.
4. Which microorganism is commonly used as an indicator of fecal
contamination in water?
A. E. coli
B. Staphylococcus aureus
C. Salmonella
D. Pseudomonas aeruginosa
A. E. coli
Rationale: E. coli is a reliable indicator of fecal contamination and
potential pathogens.
5. The purpose of coagulation in water treatment is to:
A. Increase pH
B. Remove colloidal particles
C. Disinfect water
D. Reduce hardness
B. Remove colloidal particles
Rationale: Coagulation destabilizes fine suspended particles so
they can aggregate into larger flocs.
6. Which chemical is most commonly used as a coagulant in water
treatment?
A. Sodium hypochlorite
B. Aluminum sulfate
C. Calcium carbonate
, D. Chlorine dioxide
B. Aluminum sulfate
Rationale: Aluminum sulfate (alum) is widely used because it
effectively forms flocs with suspended particles.
7. What is the main purpose of filtration in water treatment?
A. Remove dissolved minerals
B. Remove suspended solids
C. Adjust pH
D. Add disinfectant
B. Remove suspended solids
Rationale: Filtration removes remaining suspended particles after
coagulation and sedimentation.
8. Which of the following is a common method of disinfecting
water?
A. Filtration
B. Coagulation
C. Chlorination
D. Aeration
C. Chlorination
Rationale: Chlorination effectively inactivates bacteria and viruses
in drinking water.
9. In wastewater treatment, BOD stands for:
A. Biological Oxygen Demand
B. Basic Organic Dilution
C. Biochemical Oxidation Demand
D. Biological Oxidation Design
A. Biological Oxygen Demand
Rationale: BOD measures the amount of oxygen required by
microorganisms to decompose organic matter.
LEVEL IV PRACTICE QUESTIONS WITH
CORRECT ANSWERS (VERIFIED ANSWERS)
PLUS RATIONALES 2026 Q&A | INSTANT
DOWNLOAD PDF:
1. Which of the following is the primary purpose of a water
treatment plant?
A. Increase water pH
B. Remove pathogens
C. Add nutrients
D. Increase water temperature
B. Remove pathogens
Rationale: The main goal of water treatment is to make water
safe by removing disease-causing organisms.
2. What is the recommended residual chlorine level in drinking
water distribution systems?
A. 0.1–0.5 mg/L
B. 0.2–1.0 mg/L
C. 1.0–2.0 mg/L
D. 2.0–3.0 mg/L
B. 0.2–1.0 mg/L
Rationale: Maintaining 0.2–1.0 mg/L ensures disinfection while
minimizing taste and odor issues.
3. In wastewater treatment, the purpose of primary clarification is
to:
, A. Remove nutrients
B. Remove settleable solids
C. Disinfect effluent
D. Reduce BOD biologically
B. Remove settleable solids
Rationale: Primary clarifiers allow heavy solids to settle, reducing
the load on subsequent treatment processes.
4. Which microorganism is commonly used as an indicator of fecal
contamination in water?
A. E. coli
B. Staphylococcus aureus
C. Salmonella
D. Pseudomonas aeruginosa
A. E. coli
Rationale: E. coli is a reliable indicator of fecal contamination and
potential pathogens.
5. The purpose of coagulation in water treatment is to:
A. Increase pH
B. Remove colloidal particles
C. Disinfect water
D. Reduce hardness
B. Remove colloidal particles
Rationale: Coagulation destabilizes fine suspended particles so
they can aggregate into larger flocs.
6. Which chemical is most commonly used as a coagulant in water
treatment?
A. Sodium hypochlorite
B. Aluminum sulfate
C. Calcium carbonate
, D. Chlorine dioxide
B. Aluminum sulfate
Rationale: Aluminum sulfate (alum) is widely used because it
effectively forms flocs with suspended particles.
7. What is the main purpose of filtration in water treatment?
A. Remove dissolved minerals
B. Remove suspended solids
C. Adjust pH
D. Add disinfectant
B. Remove suspended solids
Rationale: Filtration removes remaining suspended particles after
coagulation and sedimentation.
8. Which of the following is a common method of disinfecting
water?
A. Filtration
B. Coagulation
C. Chlorination
D. Aeration
C. Chlorination
Rationale: Chlorination effectively inactivates bacteria and viruses
in drinking water.
9. In wastewater treatment, BOD stands for:
A. Biological Oxygen Demand
B. Basic Organic Dilution
C. Biochemical Oxidation Demand
D. Biological Oxidation Design
A. Biological Oxygen Demand
Rationale: BOD measures the amount of oxygen required by
microorganisms to decompose organic matter.
