Operator Grade I Practice Exam

Tennessee Wastewater Treatment Operator Grade I 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 nutrients

b) Remove solids that can damage equipment

c) Disinfect the wastewater

d) Reduce biological oxygen demand

b) Remove solids that can damage equipment

Rationale: Preliminary treatment removes large solids, grit, and

debris to prevent damage to pumps and other treatment units. 1 / 4

• Which unit process is typically used to remove settleable solids?

a) Trickling filter

b) Sedimentation

c) Aerated lagoon

d) Chlorination

b) Sedimentation

Rationale: Sedimentation tanks allow solids to settle by gravity,

effectively removing settleable solids from wastewater.

3. The term BOD stands for:

a) Biological Oxygen Demand

b) Basic Organic Decomposition

c) Biochemical Oxygen Difference

d) Biotic Oxidation Dose

a) Biological Oxygen Demand

Rationale: BOD measures the amount of oxygen microorganisms will

consume while decomposing organic matter in water.

• Which of the following is a common method of sludge thickening?

a) Filtration

b) Dissolved air flotation

c) Aeration

d) Chlorination

b) Dissolved air flotation 2 / 4

Rationale: Dissolved air flotation (DAF) separates solids from liquids

by using small air bubbles to float the solids to the surface.

5. The main purpose of disinfection in wastewater treatment is to:

a) Remove nutrients

b) Reduce pathogens

c) Clarify water

d) Aerate the wastewater

b) Reduce pathogens

Rationale: Disinfection kills or inactivates harmful microorganisms

before effluent is discharged.

6. Grit chambers are designed to remove:

a) Sand, gravel, and other heavy inorganic solids

b) Suspended organics

c) Fats and grease

d) Pathogens

a) Sand, gravel, and other heavy inorganic solids

Rationale: Grit chambers slow down the flow to allow heavier

inorganic particles to settle out, protecting downstream equipment.

• The primary function of an aeration tank in activated sludge systems is

to:

a) Settle solids

b) Promote microbial degradation of organic matter

c) Disinfect wastewater 3 / 4

d) Remove grit

b) Promote microbial degradation of organic matter

Rationale: Aeration tanks supply oxygen to microorganisms that

break down organic pollutants in wastewater.

8. A high sludge volume index (SVI) indicates:

a) Good settleability

b) Poor settleability

c) Low BOD removal

d) Low suspended solids

b) Poor settleability

Rationale: High SVI indicates sludge is light and fluffy, settling slowly

and potentially causing operational issues.

• Which chemical is commonly used for disinfection in wastewater

plants?

a) Ammonia

b) Chlorine

c) Sodium hydroxide

d) Ferric chloride

b) Chlorine

Rationale: Chlorine is widely used to disinfect wastewater by killing

pathogens before discharge.

10. The term “effluent” refers to:

a) Raw sewage entering the plant

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