A Practice Exam Questions And Correct

Oklahoma Wastewater Operator Class A Practice Exam Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

• What is the primary purpose of secondary treatment in a wastewater

treatment plant?

• Remove large debris
• Remove dissolved and suspended organic matter
• Disinfect the effluent
• Remove heavy metals

Rationale: Secondary treatment focuses on biological processes to

remove organic matter, typically using activated sludge or trickling filters. 1 / 4

• Which of the following is a typical indicator organism used to assess

wastewater treatment performance?

• Staphylococcus aureus
• Bacillus subtilis
• Escherichia coli
• Pseudomonas aeruginosa

Rationale: E. coli is commonly used as an indicator of fecal

contamination in wastewater.

• What is the purpose of a grit chamber in wastewater treatment?
• Remove oils and grease
• Settle heavy inorganic particles
• Treat pathogens
• Remove nutrients

Rationale: Grit chambers allow sand, gravel, and other heavy

inorganic particles to settle, protecting downstream equipment.

• Which type of wastewater treatment process uses microorganisms to

degrade organic matter in an aerated tank?

• Primary clarifier
• Activated sludge process
• Trickling filter
• Lagooning

Rationale: The activated sludge process is a biological treatment 2 / 4

where aeration provides oxygen for microorganisms to consume organic material.

• Which of the following parameters is most commonly used to measure

the organic strength of wastewater?

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

Rationale: BOD measures the amount of oxygen required by

microorganisms to break down organic matter, indicating wastewater strength.

6. Nitrification in wastewater treatment converts:

• Ammonia to nitrogen gas
• Ammonia to nitrate
• Nitrate to ammonia
• Nitrite to organic nitrogen

Rationale: Nitrification is a two-step biological process where

ammonia is oxidized first to nitrite and then to nitrate.

• The removal of phosphorus from wastewater is primarily done to

prevent:

• Pathogen growth
• Increased BOD
• Eutrophication in receiving waters 3 / 4

• TSS accumulation

Rationale: Excess phosphorus in effluent can cause algae blooms in

lakes and rivers, leading to eutrophication.

• Which of the following is a typical design consideration for a trickling

filter?

• Hydraulic retention time of 1 minute
• Media surface area for microbial attachment
• High chlorine dosage
• pH adjustment only

Rationale: Trickling filters rely on a microbial biofilm attached to a

media surface to degrade organic matter.

9. The term "sludge age" in activated sludge systems refers to:

• Age of influent wastewater
• Average time microorganisms remain in the system
• Time required for primary settling
• Age of the plant equipment

Rationale: Sludge age (or mean cell residence time) is critical for

controlling microbial populations and treatment efficiency.

• Which disinfection method uses strong oxidizing chemicals to

inactivate pathogens?

• UV radiation
• Filtration
• Chlorination
• / 4