Operator Grade 2 Practice Examination

Vermont Wastewater Treatment Facility Operator Grade 2 Practice Examination Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

• What is the primary purpose of wastewater treatment?
• Increase water hardness
• Remove contaminants to protect public health and the environment
• Add nutrients to surface waters
• Increase effluent temperature

Rationale: Treatment reduces harmful pollutants to safeguard water

bodies and public health.

• Which process is typically the first step in a conventional treatment

plant?

• Secondary clarification
• Disinfection 1 / 4

• Preliminary screening
• Aeration

Rationale: Screens remove large debris to protect downstream equipment.

• Grit removal targets which material?
• Leaves and plastics
• Fats, oils, and grease
• Pathogens
• Sand, gravel, and small inorganic particles

Rationale: Grit systems remove abrasive inorganics to prevent equipment

wear.

4. Primary clarifiers remove mainly:

• Dissolved solids
• Settleable and floatable solids
• Nitrogen only
• Phosphorus only

Rationale: Gravity settling removes heavier solids and skimming removes

floatables.

5. In activated sludge, microorganisms are mainly:

• Viruses
• Parasites
• Bacteria and protozoa
• Algae only 2 / 4

Rationale: Bacteria and protozoa stabilize organic matter in aeration

basins.

6. The food-to-microorganism (F/M) ratio relates organic loading to:

• Effluent turbidity
• Biomass concentration
• Grit quantity
• Chlorine dose

Rationale: F/M compares influent BOD to available biomass mass.

7. Low dissolved oxygen in aeration usually causes:

• Improved nitrification
• Filamentous bulking
• Lower sludge age
• Higher ORP

Rationale: Filaments thrive under low-oxygen conditions, causing poor

settling.

8. Nitrification converts:

• Nitrate to ammonia
• Ammonia to nitrate
• Nitrite to BOD
• BOD to nitrogen gas

Rationale: Nitrifying bacteria oxidize ammonia first to nitrite and then to

nitrate. 3 / 4

9. Denitrification requires:

• High dissolved oxygen
• Chlorine residual
• Anoxic conditions and a carbon source
• UV light

Rationale: Denitrifying bacteria use nitrate as an electron acceptor when

DO is absent.

10. The sludge age (SRT) is the:

• Time water stays in the headworks
• Average time biomass remains in the system
• Time needed for chlorination
• Sand drying duration

Rationale: SRT measures biomass retention and process stability.

11. Too long an SRT may cause:

• Filament growth
• Rising sludge
• Low food conditions and poor settling due to old sludge
• Excessive foaming

Rationale: Old sludge settles poorly and may lose activity.

12. Chlorination is used to:

• Add nutrients
• Remove grit
• / 4