Licensing Exam Practice Test Questions

Water Pollution Control Operator Class I Licensing Exam Practice Test Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

• What is the primary purpose of wastewater treatment?
• Remove all water
• Produce sludge only
• Protect public health and the environment
• Increase water temperature

Answer: C

Rationale: Wastewater treatment is designed to remove harmful

pollutants to protect waterways and human health.

• Which process removes large debris such as rags and sticks?
• Sedimentation
• Screening 1 / 3

• Aeration
• Filtration

Rationale: Screening is the first step and removes large solids to protect

downstream equipment.

3. Grit chambers primarily remove:

• Organic solids
• Heavy inorganic particles
• Microorganisms
• Dissolved gases

Rationale: Grit chambers target sand, gravel, and eggshells that settle

quickly.

4. Primary clarifiers remove:

• Only dissolved solids
• Settleable and floatable solids
• Pathogens
• Nitrates

Rationale: Primary treatment focuses on physical settling and floating

removal.

5. The main purpose of aeration in activated sludge is to provide:

• Chlorine
• Heat
• Oxygen 2 / 3

• Alkali

Rationale: Microbes require dissolved oxygen for biological oxidation.

6. In activated sludge, F/M ratio refers to:

• Flow/Mass
• Food/Microorganism
• Fuel/Media
• Filtration/Movement

Rationale: F/M compares organic loading to biomass quantity.

7. Sludge age (SRT) represents:

• Age of plant
• Age of pipes
• Average time microorganisms remain in system
• Tank age

Rationale: SRT reflects biomass retention time and process stability.

8. High sludge age typically improves:

• BOD removal speed
• Nitrification
• Influent flow
• Influent pH

Rationale: Older biomass supports slow-growing nitrifiers.

• A common indicator of healthy activated sludge is:
• / 3