WASTEWATER OPERATOR CLASS I
LICENSING EXAM QUESTION AND
CORRECT ANSWERS (VERIFIED
ANSWERS) PLUS RATIONALES 2026 Q&A
INSTANT DOWNLOAD PDF
1. The primary purpose of wastewater treatment is to
A. Produce drinking water
B. Recover valuable minerals
C. Protect public health and the environment
D. Generate electricity
Answer: C
Rationale: Wastewater treatment removes pollutants to prevent disease and
environmental damage.
2. Which process is considered preliminary treatment?
A. Trickling filtration
B. Activated sludge
C. Screening
D. Disinfection
Answer: C
Rationale: Screening removes large debris at the start of treatment.
3. Grit removal is important because grit
A. Improves biological treatment
B. Prevents abrasion and clogging of equipment
C. Adds nutrients
D. Reduces odors
,Answer: B
Rationale: Grit causes excessive wear and reduces system efficiency if not
removed.
4. Primary treatment mainly removes
A. Dissolved organics
B. Pathogens
C. Settleable and floatable solids
D. Nutrients
Answer: C
Rationale: Sedimentation removes solids that settle or float.
5. BOD stands for
A. Biological Oxygen Demand
B. Biochemical Oxygen Demand
C. Basic Oxygen Deficit
D. Bacterial Oxygen Demand
Answer: B
Rationale: BOD measures oxygen required by microorganisms to decompose
organic matter.
6. High BOD in receiving waters can cause
A. Increased fish populations
B. Low dissolved oxygen levels
C. Higher pH
D. Reduced turbidity
Answer: B
Rationale: Microorganisms consume oxygen while degrading organic material.
7. Secondary treatment primarily focuses on removing
A. Grit
B. Pathogens
C. Dissolved and suspended organic matter
D. Heavy metals
, Answer: C
Rationale: Biological processes target organic pollutants.
8. Activated sludge is an example of
A. Physical treatment
B. Chemical treatment
C. Biological treatment
D. Disinfection
Answer: C
Rationale: Microorganisms break down organic matter.
9. The main microorganisms in activated sludge are
A. Algae
B. Viruses
C. Bacteria and protozoa
D. Worms
Answer: C
Rationale: These organisms metabolize organic pollutants.
10.Dissolved oxygen in an aeration tank is typically maintained at
A. 0 mg/L
B. 0.5 mg/L
C. 1–3 mg/L
D. 10 mg/L
Answer: C
Rationale: This range supports efficient microbial activity.
11.A clarifier is used to
A. Aerate wastewater
B. Add chemicals
C. Separate solids from liquids
D. Kill bacteria
Answer: C
Rationale: Clarifiers allow solids to settle or float for removal.
LICENSING EXAM QUESTION AND
CORRECT ANSWERS (VERIFIED
ANSWERS) PLUS RATIONALES 2026 Q&A
INSTANT DOWNLOAD PDF
1. The primary purpose of wastewater treatment is to
A. Produce drinking water
B. Recover valuable minerals
C. Protect public health and the environment
D. Generate electricity
Answer: C
Rationale: Wastewater treatment removes pollutants to prevent disease and
environmental damage.
2. Which process is considered preliminary treatment?
A. Trickling filtration
B. Activated sludge
C. Screening
D. Disinfection
Answer: C
Rationale: Screening removes large debris at the start of treatment.
3. Grit removal is important because grit
A. Improves biological treatment
B. Prevents abrasion and clogging of equipment
C. Adds nutrients
D. Reduces odors
,Answer: B
Rationale: Grit causes excessive wear and reduces system efficiency if not
removed.
4. Primary treatment mainly removes
A. Dissolved organics
B. Pathogens
C. Settleable and floatable solids
D. Nutrients
Answer: C
Rationale: Sedimentation removes solids that settle or float.
5. BOD stands for
A. Biological Oxygen Demand
B. Biochemical Oxygen Demand
C. Basic Oxygen Deficit
D. Bacterial Oxygen Demand
Answer: B
Rationale: BOD measures oxygen required by microorganisms to decompose
organic matter.
6. High BOD in receiving waters can cause
A. Increased fish populations
B. Low dissolved oxygen levels
C. Higher pH
D. Reduced turbidity
Answer: B
Rationale: Microorganisms consume oxygen while degrading organic material.
7. Secondary treatment primarily focuses on removing
A. Grit
B. Pathogens
C. Dissolved and suspended organic matter
D. Heavy metals
, Answer: C
Rationale: Biological processes target organic pollutants.
8. Activated sludge is an example of
A. Physical treatment
B. Chemical treatment
C. Biological treatment
D. Disinfection
Answer: C
Rationale: Microorganisms break down organic matter.
9. The main microorganisms in activated sludge are
A. Algae
B. Viruses
C. Bacteria and protozoa
D. Worms
Answer: C
Rationale: These organisms metabolize organic pollutants.
10.Dissolved oxygen in an aeration tank is typically maintained at
A. 0 mg/L
B. 0.5 mg/L
C. 1–3 mg/L
D. 10 mg/L
Answer: C
Rationale: This range supports efficient microbial activity.
11.A clarifier is used to
A. Aerate wastewater
B. Add chemicals
C. Separate solids from liquids
D. Kill bacteria
Answer: C
Rationale: Clarifiers allow solids to settle or float for removal.
