Practice Exam Questions And Correct

Nebraska Wastewater Operator Grade I 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:

• Generate electricity
• Produce drinking water
• Remove pollutants from wastewater
• Increase wastewater volume

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

remove contaminants to protect public health and the environment.

• Which of the following is considered a physical method of wastewater

treatment?

• Screening 1 / 4

• Chlorination
• Activated sludge
• Trickling filter

Rationale: Screening removes large solids from wastewater through

a physical barrier without chemical or biological processes.

• What is the primary function of grit chambers in wastewater

treatment?

• Remove oils
• Remove dissolved solids
• Remove sand, gravel, and other heavy inorganic solids
• Promote bacterial growth

Rationale: Grit chambers are designed to settle out heavy inorganic

solids like sand and gravel to prevent damage to pumps and other equipment.

• Which parameter is most commonly used to measure organic

pollution in wastewater?

• pH
• Biochemical Oxygen Demand (BOD)
• Total Suspended Solids (TSS)
• Chlorine residual

Rationale: BOD measures the amount of oxygen required by

microorganisms to decompose organic matter, indicating organic pollution levels. 2 / 4

5. In a sedimentation tank, solids settle primarily due to:

• Chemical reaction
• Gravity
• Filtration
• Evaporation

Rationale: Sedimentation relies on gravity to allow heavier solids to

settle to the bottom of tanks.

• What is the typical purpose of a chlorine contact tank?
• Remove solids
• Adjust pH
• Disinfect wastewater
• Increase flow rate

Rationale: Chlorine contact tanks provide sufficient time and

concentration for chlorine to inactivate pathogens.

• Which of the following is a primary treatment process?
• Activated sludge
• Sedimentation
• Trickling filter
• Nitrification

Rationale: Primary treatment focuses on physical processes like

sedimentation to remove settleable solids.

• What is the purpose of an aeration tank in activated sludge systems?
• Settle solids 3 / 4

• Provide oxygen to bacteria for organic matter breakdown
• Remove grit
• Disinfect effluent

Rationale: Aeration supplies oxygen to support microbial

decomposition of organic matter.

• Which of the following best defines sludge?
• Treated effluent
• Settled solids removed during treatment
• Disinfectant residual
• Influent wastewater

Rationale: Sludge is the concentrated solid matter separated from

wastewater during treatment.

• Which process is primarily responsible for removing nitrogen in

a wastewater treatment plant?

• Sedimentation
• Coagulation
• Biological nitrification and denitrification
• Filtration

Rationale: Biological nitrogen removal uses nitrifying and

denitrifying bacteria to convert ammonia to nitrogen gas.

• What does TSS measure in wastewater?
• Dissolved oxygen
• pH
• / 4