Level 1 Practice Exam Questions And

Yukon Wastewater Treatment Operator Level 1 Practice Exam Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

• Which of the following best describes the primary purpose of

wastewater treatment?

a) To remove all bacteria from water

b) To remove pollutants and protect public health and the

environment

c) To increase the temperature of water

d) To desalinate water

Rationale: Wastewater treatment is designed to remove pollutants

and pathogens to protect human health and the environment, not to sterilize or desalinate water. 1 / 4

• What is the typical first step in a municipal wastewater treatment

plant?

a) Preliminary treatment

b) Secondary treatment

c) Tertiary treatment

d) Disinfection

Rationale: Preliminary treatment removes large debris and solids

through screening and grit removal before further processing.

• Which process is considered secondary treatment in wastewater

facilities?

a) Screening

b) Biological treatment using bacteria

c) Sedimentation

d) Chlorination

Rationale: Secondary treatment uses biological processes, often with

bacteria, to remove dissolved and suspended organic matter.

4. In wastewater treatment, BOD stands for:

a) Biological Oxidation Degree

b) Biochemical Oxidation Demand

c) Biochemical Oxygen Demand

d) Bacterial Oxidation Demand

Rationale: BOD measures the amount of oxygen microorganisms

need to decompose organic matter in water. 2 / 4

• What is the primary purpose of screening in preliminary treatment?

a) Remove dissolved nutrients

b) Remove large solids and debris

c) Remove bacteria

d) Remove dissolved oxygen

Rationale: Screening removes large items like rags, sticks, and

plastics to prevent damage to equipment downstream.

6. Grit chambers are used to remove:

a) Bacteria

b) Oils and grease

c) Sand, gravel, and small inorganic solids

d) Suspended organic matter

Rationale: Grit chambers slow water velocity, allowing heavier

inorganic particles to settle.

• Which type of sedimentation tank is commonly used for primary

treatment?

a) Circular clarifier

b) Trickling filter

c) Primary clarifier

d) Aeration basin

Rationale: Primary clarifiers allow solids to settle out of wastewater

before secondary treatment. 3 / 4

• Which microorganism type is primarily responsible for degrading

organic matter in activated sludge?

a) Viruses

b) Protozoa

c) Bacteria

d) Fungi

Rationale: Bacteria metabolize organic matter, reducing BOD in

secondary treatment.

9. The main purpose of aeration in secondary treatment is to:

a) Remove grit

b) Filter water

c) Supply oxygen for microorganisms to degrade organic matter

d) Remove chlorine

Rationale: Aeration ensures sufficient dissolved oxygen for aerobic

bacteria to process organic pollutants.

• What does TSS stand for in wastewater analysis?

a) Total Soluble Substances

b) Total Suspended Solids

c) Total Sediment Sample

d) Total Soluble Solids

Rationale: TSS measures the concentration of particles suspended in

water, an important indicator of treatment efficiency.

• / 4