Exam Questions And Correct Answers Verified

Food and Beverage Industrial Waste Treatment Operator Certification Practice Exam Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

• What is the main purpose of a primary clarifier in wastewater

treatment?

• To oxidize organic matter
• To remove settleable and floatable solids
• To disinfect effluent
• To remove nutrients

Rationale: Primary clarifiers settle heavy solids and skim floating materials

before biological treatment.

2. The main parameter used to measure organic load in wastewater is:

A. TSS

B. BOD

• DO

D. COD 1 / 3

Rationale: Biochemical Oxygen Demand (BOD) represents biodegradable

organic content.

• What is the typical pH range for optimal biological treatment?

A. 3–5

B. 6.5–8.5

C. 8.5–10

D. 5–6

Rationale: Microorganisms in activated sludge perform best in near-neutral

conditions.

4. In anaerobic digestion, the primary gas produced is:

• Oxygen
• Methane
• Nitrogen
• Hydrogen sulfide

Rationale: Methane is the major product of anaerobic decomposition of

organic matter.

• What is the typical detention time in a primary clarifier?
• 10–15 hours
• 1.5–3 hours
• 5–8 hours
• 0.5 hour

Rationale: Short detention time prevents septic conditions while allowing

solids to settle. 2 / 3

6. Sludge volume index (SVI) measures:

• BOD removal rate
• Settling characteristics of activated sludge
• Oxygen uptake rate
• Total nitrogen content

Rationale: SVI indicates sludge settleability in the secondary clarifier.

7. The F/M ratio represents the relationship between:

• Flow and microorganism count
• Food (BOD) and microorganisms (MLVSS)
• Filtrate and moisture
• Fat and mineral content

Rationale: The Food-to-Microorganism ratio determines system loading and

stability.

8. The main cause of filamentous bulking in activated sludge is:

• High F/M ratio
• Low DO and nutrient imbalance
• Excess aeration
• High alkalinity

Rationale: Low oxygen or poor nutrient balance favors filamentous bacteria

growth.

• Which process uses microorganisms in the absence of oxygen?
• Aerobic digestion
• Nitrification
• / 3