Level 2 Practice Exam 100 Questions And

Alberta Wastewater Treatment Operator Level 2 Practice Exam 100 Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

• What is the main purpose of primary clarification in wastewater

treatment?

• Remove dissolved solids
• Remove settleable and floatable solids
• Reduce BOD by biological means
• Nitrify ammonia

Primary clarifiers allow heavier solids to settle and lighter materials to float, reducing TSS and some BOD load to secondary treatment.

• Typical detention time for a primary clarifier is: 1 / 3

• 5–10 minutes
• 10–20 minutes
• 1.5–2.5 hours
• 10–12 hours

Primary clarification requires long enough time for solids to settle, normally around 1.5–2.5 hours.

• What is the ideal MLSS range for a conventional activated sludge

process?

• 100–300 mg/L
• 300–500 mg/L
• 1,500–3,000 mg/L
• 6,000–8,000 mg/L

Conventional activated sludge operates best at MLSS in the 1,500–3,000 mg/L range.

• Which microorganism is primarily responsible for nitrification?
• Protozoa
• Nitrifying bacteria
• Fungi
• Viruses

Nitrification is a two-step biological oxidation carried out by ammonia and nitrite oxidizing bacteria.

• What is the purpose of return activated sludge (RAS)? 2 / 3

• Increase DO
• Remove pathogens
• Maintain biomass concentration
• Remove phosphorus

RAS returns settled biomass to the aeration tank to maintain adequate microbial population.

• Which factor most influences oxygen transfer efficiency in aeration

systems?

• Water temperature only
• Bubble size
• Pipe diameter
• Clarifier depth

Smaller bubbles have more surface area, increasing oxygen transfer efficiency.

7. A high F/M ratio typically results in:

• Low microbial growth
• Older sludge
• Young, rapidly growing biomass
• High sludge age

High food relative to microorganisms results in young, fast-growing biomass.

8. Sludge bulking is often caused by:

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