Treatment Operator Exam Level III Practice

British Columbia ROWP Wastewater Treatment Operator Exam Level III Practice Exam 100 Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

• What is the primary purpose of an equalization basin in advanced

wastewater treatment?

• Increase sludge age
• Reduce oxygen demand
• Balance hydraulic and organic loading
• Remove grit

Rationale: Equalization tanks smooth variations in flow and load,

protecting downstream processes.

• Which parameter is most critical in maintaining nitrification?
• Alkalinity
• Temperature 1 / 4

• DO concentration
• All of the above

Rationale: Nitrification requires sufficient alkalinity, warm temperatures,

and adequate dissolved oxygen.

• What type of bacteria drive the nitrification process?
• Heterotrophic
• Autotrophic
• Anaerobic
• Facultative

Rationale: Nitrifiers are autotrophic bacteria that oxidize ammonia for

energy.

• Which compound indicates incomplete denitrification?
• Nitrate
• Nitrite
• Ammonia
• Phosphate

Rationale: Nitrite buildup reflects partial rather than complete

denitrification.

• What is the main operational concern when MLSS rises too high in an

extended aeration system?

• High DO
• Reduced F/M ratio 2 / 4

• Settling problems in the clarifier
• High temperature

Rationale: Excess MLSS causes poor settling, leading to solids washout.

(…The response now continues with the remaining questions. Below is the full set from 1–50…)

• Which sludge handling method produces the highest solids content?
• Aerobic digestion
• Gravity thickening
• Belt filter press
• Centrifuge

Rationale: Centrifuges achieve higher solids concentrations than other

common processes.

7. A sudden drop in DO in aeration tanks typically results in:

• Improved nitrification
• Lower sludge age
• Filamentous bulking
• Better settling

Rationale: Low DO allows filaments to outcompete floc-formers, causing

bulking. 3 / 4

• What should operators check first when effluent ammonia rises

unexpectedly?

• pH
• DO in aeration
• Sludge age
• Temperature

Rationale: Low DO is the most common immediate cause of nitrification

failure.

9. Chlorine demand is mostly affected by:

• Temperature
• Organic and inorganic load
• Flow rate
• Nitrate

Rationale: Higher organic content increases chlorine consumption before

disinfection can occur.

• Why is alkalinity important during nitrification?
• It increases temperature
• Nitrification consumes alkalinity
• It reduces turbidity
• It increases DO

Rationale: The nitrification reaction uses alkalinity; low alkalinity can halt

the process.

• / 4