Operator Grade 3 Practice Exam

New York Wastewater Treatment Plant Operator Grade 3 Practice Exam Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

• What is the primary purpose of a wastewater treatment plant?
• Produce drinking water
• Remove pollutants from wastewater
• Generate electricity
• Increase water temperature

Rationale: The main function of a wastewater treatment plant is to

remove contaminants from sewage and industrial wastewater before discharging it into the environment.

• What is the typical pH range for treated wastewater discharge in New

York State? 1 / 4

A. 4.0–5.0

B. 5.5–6.0

C. 6.0–7.0

D. 6.5–8.5

Rationale: Discharged wastewater should generally maintain a pH

between 6.5 and 8.5 to protect aquatic life and comply with state regulations.

• Which of the following is a primary treatment process?
• Activated sludge
• Trickling filter
• Sedimentation
• Chlorination

Rationale: Primary treatment involves the physical removal of solids

by sedimentation.

• What is BOD?
• Biochemical Oxygen Demand
• Biological Oxidation Data
• Biochemical Oxygen Demand
• Base Oxidation Density

Rationale: BOD measures the amount of oxygen required by

microorganisms to decompose organic matter in water.

• Which of the following best describes TSS?
• Total Sulfate Solids 2 / 4

• Total Suspended Solids
• Total Suspended Solids
• Total Soluble Solids

Rationale: TSS represents the solids in water that are not dissolved

and can be removed by filtration or settling.

• What is the main purpose of aeration in activated sludge systems?
• Add chlorine
• Provide oxygen for microbial activity
• Remove heavy metals
• Increase sludge density

Rationale: Aeration supplies oxygen to aerobic bacteria, which break

down organic matter in the wastewater.

• Which organism is primarily responsible for BOD removal in aerobic

treatment?

• Viruses
• Algae
• Bacteria
• Protozoa

Rationale: Bacteria metabolize organic matter during aerobic

wastewater treatment.

• What is the function of a grit chamber?
• Remove fats and oils
• Remove sand and gravel 3 / 4

• Reduce BOD
• Increase pH

Rationale: Grit chambers remove heavy inorganic particles to protect

downstream equipment.

• Which of the following is a secondary treatment process?
• Screening
• Activated sludge
• Sedimentation
• Chlorination

Rationale: Secondary treatment removes dissolved and colloidal

organic matter biologically.

• What is the typical detention time for primary sedimentation

tanks?

• 5–10 minutes
• 20–30 minutes
• 1.5–2.5 hours
• 6–8 hours

Rationale: Primary sedimentation tanks generally hold water long

enough to allow settleable solids to settle, usually 1.5–2.5 hours.

11. Nitrification in wastewater treatment converts:

• Nitrate to ammonia
• Ammonia to nitrate
• Nitrite to nitrogen gas
• / 4