Practice Exam Questions And Correct

Michigan Wastewater Operator Class B Practice Exam 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:

• Produce drinking water
• Remove solids, organics, and pathogens from wastewater
• Increase the flow of water in rivers
• Generate electricity
• Remove solids, organics, and pathogens from wastewater

Rationale: The main objective of wastewater treatment is to remove

pollutants to protect public health and the environment.

• Which of the following is a commonly used biological treatment

process? 1 / 4

• Chlorination
• Activated sludge
• Screening
• Sedimentation
• Activated sludge

Rationale: Activated sludge is a biological process that uses microorganisms

to degrade organic matter in wastewater.

3. BOD (Biochemical Oxygen Demand) measures:

• Total dissolved solids in water
• The amount of oxygen required by microorganisms to decompose

organic matter

• pH level of wastewater
• Concentration of heavy metals
• The amount of oxygen required by microorganisms to decompose

organic matter

Rationale: BOD indicates the organic pollution load and the oxygen demand

wastewater places on a treatment system.

4. TSS stands for:

• Total Suspended Solids
• Total Soluble Salts
• Temperature Sensitivity Standard
• Total Sulfate Solids 2 / 4

• Total Suspended Solids

Rationale: TSS measures the concentration of particles suspended in

wastewater, important for assessing treatment efficiency.

5. In wastewater treatment, primary sedimentation primarily removes:

• Dissolved nutrients
• Settleable solids
• Microorganisms
• Dissolved gases
• Settleable solids

Rationale: Primary sedimentation allows heavy solids to settle out before

biological treatment.

6. Aeration in an activated sludge system is necessary to:

• Remove nitrogen
• Supply oxygen for microbial degradation
• Disinfect wastewater
• Remove heavy metals
• Supply oxygen for microbial degradation

Rationale: Aeration provides the dissolved oxygen needed by bacteria to

break down organic matter.

• The sludge age (mean cell residence time) in an activated sludge

system affects:

• Effluent pH 3 / 4

• BOD removal efficiency
• Chlorine demand
• TSS measurement
• BOD removal efficiency

Rationale: Longer sludge ages generally improve biological treatment and

BOD removal.

8. Nitrification is the biological conversion of:

• Ammonia to nitrate
• Nitrate to ammonia
• Organic carbon to methane
• Phosphate to phosphate solids
• Ammonia to nitrate

Rationale: Nitrification involves autotrophic bacteria converting ammonia to

nitrite and then nitrate.

9. Denitrification is the process of converting:

• Nitrate to nitrogen gas
• Ammonia to nitrate
• Nitrite to ammonia
• Phosphate to solids
• Nitrate to nitrogen gas

Rationale: Denitrification is an anoxic process where bacteria reduce nitrate

to nitrogen gas, removing nitrogen from wastewater.

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