Operator Grade 2 Practice Exam

New York Wastewater Treatment Plant Operator Grade 2 Practice Exam Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

• The primary purpose of preliminary treatment in a wastewater plant is

to:

a) Remove dissolved organic matter

b) Remove large solids and debris

c) Remove nutrients

d) Disinfect wastewater

Rationale: Preliminary treatment involves screening and grit removal to

protect downstream equipment and prevent clogging.

• Which of the following is a common indicator organism for fecal

contamination in water? 1 / 4

a) Clostridium perfringens

b) Legionella pneumophila

c) Escherichia coli

d) Staphylococcus aureus

Rationale: E. coli is commonly used as an indicator of fecal contamination

because it is abundant in the intestines of warm-blooded animals.

3. The typical pH range for activated sludge processes is:

• 4.5–5.5
• 6.5–8.5
• 8.5–10.0
• 3.0–6.0

Rationale: Most biological treatment processes operate efficiently in a

near-neutral pH range.

• The primary function of a clarifier in a wastewater treatment plant is

to:

a) Aerate wastewater

b) Separate solids from liquids

c) Remove nutrients

d) Disinfect effluent

Rationale: Clarifiers allow suspended solids to settle by gravity, producing

a clarified liquid and sludge. 2 / 4

• Which chemical is commonly used for disinfection in wastewater

treatment?

a) Chlorine dioxide

b) Chlorine

c) Ozone

d) Ferric chloride

Rationale: Chlorine is the most widely used disinfectant due to its

effectiveness and ease of application.

• What is the main purpose of aeration in activated sludge systems?

a) Reduce pH

b) Provide oxygen for microorganisms

c) Remove grit

d) Settle solids

Rationale: Aeration supplies oxygen, which is essential for aerobic

microorganisms to metabolize organic matter.

7. The term BOD stands for:

a) Biochemical Oxidation Demand

b) Biological Organic Density

c) Biochemical Oxygen Demand

d) Biological Oxygen Density

Rationale: BOD measures the amount of oxygen required by

microorganisms to decompose organic matter in water. 3 / 4

8. Nitrification in wastewater treatment involves:

a) Conversion of nitrate to ammonia

b) Conversion of ammonia to nitrate

c) Conversion of nitrite to ammonia

d) Removal of organic solids

Rationale: Nitrification is a two-step aerobic process where ammonia is

oxidized to nitrite and then to nitrate.

9. Sludge digestion is primarily used to:

a) Increase solids content

b) Stabilize organic matter

c) Remove metals

d) Reduce chlorine demand

Rationale: Digestion reduces the amount of volatile solids, odor, and

pathogen content.

• Which parameter is commonly used to measure the strength of

wastewater?

a) Turbidity

b) BOD

• pH

d) Dissolved oxygen

Rationale: BOD indicates the amount of biodegradable organic matter

present in wastewater.

• / 4