Practice Exam Questions And Correct

Michigan Wastewater Operator Class C Practice Exam 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 generate electricity
• To produce potable water
• To remove contaminants from wastewater before discharge
• To collect rainwater

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

wastewater to a level that is safe for the environment or reuse.

• Which of the following is a common indicator of organic pollution in

wastewater?

• pH 1 / 4

• Biochemical Oxygen Demand (BOD)
• Turbidity
• Temperature

Rationale: BOD measures the amount of oxygen required by

microorganisms to decompose organic matter, indicating organic pollution.

3. The term “TSS” in wastewater treatment refers to:

• Total Soluble Salts
• Total Suspended Solids
• Total Sulfate Solids
• Temperature and Salinity Standard

Rationale: TSS indicates the concentration of suspended particles in water,

which can impact treatment efficiency and discharge quality.

• In activated sludge systems, microorganisms are primarily responsible

for:

• Removing heavy metals
• Decomposing organic matter
• Disinfecting wastewater
• Settling solids

Rationale: Microorganisms in activated sludge consume and break down

organic pollutants, reducing BOD. 2 / 4

• Which unit process is used to remove grit from wastewater?
• Primary clarifier
• Grit chamber
• Aeration tank
• Secondary clarifier

Rationale: Grit chambers remove heavy inorganic materials like sand and

gravel that can damage equipment.

6. The primary purpose of screening in wastewater treatment is to:

• Remove dissolved organics
• Remove nutrients
• Remove large solids and debris
• Reduce BOD

Rationale: Screens prevent large objects from entering downstream

equipment, protecting pumps and clarifiers.

7. A typical pH range for municipal wastewater is:

A. 2.0 – 4.0

B. 5.0 – 6.0

C. 6.5 – 8.5

D. 9.0 – 11.0

Rationale: Most municipal wastewater is slightly acidic to slightly alkaline,

around neutral pH. 3 / 4

• Which process primarily removes nitrogen from wastewater?
• Chlorination
• Biological nitrification and denitrification
• Sedimentation
• Filtration

Rationale: Nitrogen is removed biologically by converting ammonia to

nitrate (nitrification) and then to nitrogen gas (denitrification).

• Which of the following is a disinfectant commonly used in wastewater

treatment?

• Sodium hydroxide
• Chlorine
• Sulfuric acid
• Calcium carbonate

Rationale: Chlorine is widely used to kill pathogenic organisms before

effluent discharge.

10. The term “hydraulic retention time (HRT)” refers to:

• Volume of sludge per day
• Average time wastewater spends in a treatment unit
• Flow rate of influent
• Amount of BOD removed

Rationale: HRT indicates how long water remains in a tank, impacting

treatment effectiveness.

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