Exam Practice Questions And Correct

Montana Wastewater Operator Class 4 Exam Practice Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

• What is the primary purpose of a wastewater treatment plant?
• To supply drinking water
• To remove contaminants from wastewater
• To generate electricity
• To desalinate water

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

remove pollutants to protect public health and the environment.

• Which process is used to remove suspended solids from wastewater?
• Filtration
• Sedimentation 1 / 4

• Chlorination
• Aeration

Rationale: Sedimentation allows solids to settle out of the water by

gravity, which is a primary treatment step.

3. Biological treatment in wastewater relies primarily on:

• Chemicals
• UV light
• Microorganisms
• Sedimentation

Rationale: Microorganisms break down organic matter in

wastewater during secondary treatment.

• What does BOD measure?
• Chlorine demand
• Total dissolved solids
• Oxygen required to biologically degrade organic matter
• pH levels

Rationale: Biochemical Oxygen Demand (BOD) indicates the amount

of oxygen microorganisms need to decompose organic material.

• Which pathogen is most commonly monitored in wastewater?
• Hepatitis A
• Coliform bacteria
• Influenza virus
• Salmonella 2 / 4

Rationale: Coliform bacteria are indicator organisms for the potential

presence of pathogenic microbes in wastewater.

6. Nitrification is the process of converting:

• Nitrogen gas to ammonia
• Ammonia to nitrate
• Nitrate to nitrogen gas
• Nitrite to ammonia

Rationale: Nitrification is a two-step aerobic process converting

ammonia to nitrite and then to nitrate.

• Denitrification occurs under what conditions?
• Aerobic
• Anaerobic
• High temperature
• High pH

Rationale: Denitrification is an anaerobic process where nitrate is

converted to nitrogen gas.

8. Phosphorus is primarily removed from wastewater by:

• Filtration
• Chlorination
• Chemical precipitation
• UV disinfection

Rationale: Chemicals like alum or ferric chloride are added to

precipitate phosphorus for removal. 3 / 4

9. The primary clarifier is designed to remove:

• Dissolved organics
• Settleable solids
• Pathogens
• Heavy metals

Rationale: Primary clarifiers remove settleable solids by allowing

particles to settle to the bottom.

10. Sludge thickening is used to:

• Reduce pathogen content
• Reduce water content of sludge
• Remove heavy metals
• Aerate wastewater

Rationale: Thickening increases solids concentration, reducing sludge

volume before treatment or disposal.

• Which chemical is commonly used for disinfection in wastewater

treatment?

• Ammonia
• Chlorine
• Alum
• Ferric chloride

Rationale: Chlorine is widely used to kill pathogens in treated

effluent.

• / 4