Treatment Operator Level 2 Exam Practice

Newfoundland and Labrador Wastewater Treatment Operator Level 2 Exam Practice Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

1. The primary purpose of a wastewater treatment plant is to:

a) Generate electricity

b) Remove pollutants from wastewater

c) Increase water hardness

d) Produce drinking water

b) Remove pollutants from wastewater

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

remove physical, chemical, and biological pollutants to protect human health and the environment.

• Which of the following is considered a primary treatment process?

a) Chlorination 1 / 4

b) Screening

c) Activated sludge

d) Trickling filter

b) Screening

Rationale: Primary treatment involves physical processes like

screening and sedimentation to remove large solids from wastewater.

3. Biological treatment in wastewater plants primarily removes:

a) Heavy metals

b) Organic matter

c) Sand and grit

d) Chlorine

b) Organic matter

Rationale: Biological treatment uses microorganisms to break down

and remove organic pollutants from wastewater.

• Which parameter measures the oxygen demand of wastewater over 5

days at 20°C?

a) COD

b) BOD5

c) TSS

• pH

b) BOD5

Rationale: BOD5 (Biochemical Oxygen Demand over 5 days) 2 / 4

measures the amount of oxygen microorganisms require to degrade organic matter at 20°C.

5. The most common method for disinfecting treated wastewater is:

a) Sedimentation

b) Chlorination

c) Aeration

d) Filtration

b) Chlorination

Rationale: Chlorination is widely used because it effectively kills

pathogenic microorganisms in treated wastewater.

6. Total suspended solids (TSS) primarily consist of:

a) Dissolved salts

b) Particulate matter

c) Dissolved oxygen

d) Nutrients

b) Particulate matter

Rationale: TSS measures particles suspended in wastewater,

including silt, organic material, and microorganisms.

7. A common cause of sludge bulking in activated sludge systems is:

a) High DO levels

b) Filamentous bacteria overgrowth

c) Excess chlorination

d) Low pH 3 / 4

b) Filamentous bacteria overgrowth

Rationale: Filamentous bacteria can overgrow and prevent proper

settling of sludge, causing bulking in activated sludge systems.

8. Nitrification in wastewater treatment converts:

a) Ammonia to nitrate

b) Nitrate to ammonia

c) Nitrite to chlorine

d) Phosphate to nitrate

a) Ammonia to nitrate

Rationale: Nitrification is a two-step biological process where

ammonia is oxidized to nitrite and then to nitrate.

9. Denitrification converts:

a) Nitrate to nitrogen gas

b) Ammonia to nitrite

c) Organic matter to BOD

d) Phosphate to nitrate

a) Nitrate to nitrogen gas

Rationale: Denitrification is an anaerobic process where nitrate is

converted into nitrogen gas, removing nitrogen from wastewater.

10. The purpose of an aeration tank in secondary treatment is to:

a) Settle solids

b) Provide oxygen to microorganisms

c) Remove grit

• / 4