Operator Grade I Practice Exam

Nevada Wastewater Treatment Plant Operator Grade I Practice Exam Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

• Which of the following is the primary function of a wastewater

treatment plant?

• Generate electricity
• Remove contaminants from wastewater
• Produce drinking water
• Store wastewater

Rationale: The main purpose of a wastewater treatment plant is to remove

physical, chemical, and biological contaminants to protect public health and the environment. 1 / 4

• What is the first step in wastewater treatment?
• Biological treatment
• Preliminary treatment (screening and grit removal)
• Disinfection
• Sludge digestion

Rationale: Preliminary treatment removes large debris and grit to prevent

damage to downstream equipment.

• What is the purpose of a grit chamber?
• Remove organic matter
• Remove sand, gravel, and other heavy particles
• Reduce nitrogen
• Add chemicals to wastewater

Rationale: Grit chambers allow heavy inorganic particles to settle while

letting lighter organic material continue downstream.

• Which process is used to reduce the biological oxygen demand (BOD)

in wastewater?

• Sedimentation
• Aerobic biological treatment
• Filtration
• Chlorination

Rationale: Aerobic microorganisms metabolize organic matter, reducing

BOD levels. 2 / 4

5. Primary clarifiers are used to:

• Remove settleable solids
• Remove dissolved chemicals
• Disinfect water
• Remove nutrients

Rationale: Primary clarifiers allow solids to settle out of the wastewater by

gravity.

• Which of the following is a sign of a properly functioning aeration

tank?

• No foam
• Steady sludge volume and adequate dissolved oxygen
• Strong ammonia smell
• Floating scum layer

Rationale: Proper aeration ensures sufficient oxygen for microbial activity,

resulting in stable sludge and odor control.

• What does BOD stand for?
• Biological Oxidation Demand
• Biochemical Oxygen Demand
• Basic Oxygen Density
• Biochemical Oxidation Depth

Rationale: BOD measures the amount of dissolved oxygen needed by

microorganisms to decompose organic matter in water. 3 / 4

• Which type of microorganism primarily removes ammonia in

nitrification?

• Fungi
• Nitrifying bacteria
• Protozoa
• Viruses

Rationale: Nitrifying bacteria convert ammonia to nitrite and then nitrate

during nitrification.

9. In wastewater, pH is important because:

• It determines water temperature
• It affects microbial activity and chemical reactions
• It measures oxygen content
• It indicates solids concentration

Rationale: Microorganisms and chemical treatments function optimally

within specific pH ranges.

• Which chemical is commonly used for disinfection in wastewater

treatment?

• Fluoride
• Chlorine
• Ammonia
• Sulfate
• / 4