D Exam Practice Questions And Correct

Oklahoma Wastewater Operator Class D Exam And ( Answers) Plus Rationales 2026 Q&A Instant Download Pdf

• What is the primary purpose of a wastewater treatment plant?
• Produce drinking water
• Remove contaminants from wastewater to protect public health

and the environment

• Generate electricity
• Supply water for irrigation

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

pollutants from wastewater so it can be safely discharged or reused.

• Which of the following is considered a physical treatment process?
• Chlorination 1 / 4

• Sedimentation
• Biological treatment
• Aeration

Rationale: Sedimentation is a physical process where solids settle out of

wastewater by gravity.

3. The term BOD stands for:

• Biochemical Oxidation Demand
• Biochemical Oxygen Demand
• Biological Oxidation Determination
• Basic Oxygen Demand

Rationale: BOD measures the amount of dissolved oxygen needed by

microorganisms to decompose organic matter in water.

• What is the purpose of screening in a wastewater plant?
• Remove dissolved solids
• Remove large solids and debris
• Reduce nutrient levels
• Kill bacteria

Rationale: Screens are used to remove rags, sticks, and other large debris

to prevent damage to equipment.

• Which process uses microorganisms to remove organic matter from

wastewater?

• Sedimentation 2 / 4

• Filtration
• Biological treatment
• Chlorination

Rationale: Biological treatment relies on microorganisms to break down

organic pollutants in wastewater.

• What is the typical first step in primary treatment?
• Chlorination
• Screening and grit removal
• Aeration
• Sludge digestion

Rationale: Primary treatment removes large solids and grit before further

treatment.

• Which of the following is a chemical method for disinfection?
• UV light
• Ozone
• Chlorination
• Filtration

Rationale: Chlorination is a common chemical method used to kill

pathogens in wastewater.

• What is the function of an aeration tank in activated sludge

treatment?

• Remove grit 3 / 4

• Provide oxygen for microorganisms to digest organic matter
• Filter solids
• Neutralize pH

Rationale: Aeration supplies oxygen to bacteria, which is necessary for the

biological breakdown of waste.

• Which of the following is a common problem caused by too much

grease in wastewater?

• Low BOD
• Clogged pipes and pumps
• Excess oxygen
• Reduced solids settling

Rationale: Grease can solidify and accumulate, causing blockages in the

system.

• What does TSS stand for in wastewater treatment?
• Total Salt Solution
• Total Sediment Saturation
• Total Suspended Solids
• Total Soluble Solids

Rationale: TSS measures the amount of suspended particles in wastewater.

• Which of the following is true about anaerobic digestion of

sludge?

• Requires oxygen
• / 4