Practice Exam Questions And Correct

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

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

plant?

• Remove nutrients
• Reduce BOD
• Remove large debris
• Stabilize sludge
• Remove large debris

Preliminary treatment protects downstream equipment by removing rags, grit, and large solids.

• Which parameter is used to estimate the strength of wastewater?
• Chlorine demand 1 / 4

• Turbidity
• pH

D. BOD

D. BOD

BOD represents biodegradable organic load, a key measure of wastewater strength.

3. The primary function of grit removal is to:

• Remove organic solids
• Prevent abrasion and wear
• Reduce odors
• Aid in disinfection
• Prevent abrasion and wear

Grit damages pumps and mechanical equipment; removal protects plant infrastructure.

• What is the typical detention time in a primary clarifier?
• 10–20 minutes
• 30–60 minutes
• 1.5–2.5 hours
• 4–6 hours
• 1.5–2.5 hours

This range allows sufficient settling of primary solids without septic conditions. 2 / 4

5. In activated sludge, MLSS refers to:

• Mixed liquor suspended solids
• Mixed lagoon solids
• Minimum level solids
• Microbial loading solids
• Mixed liquor suspended solids

MLSS measures the total solids concentration in the aeration basin.

• What is the purpose of RAS?
• Increase DO
• Return biomass to aeration
• Waste excess sludge
• Measure BOD
• Return biomass to aeration

RAS maintains required biomass by returning settled organisms to the aeration tank.

• Which gas is commonly produced in anaerobic digestion?
• Oxygen
• Nitrogen
• Carbon monoxide
• Methane
• Methane

Anaerobic digestion produces biogas largely composed of methane and carbon dioxide. 3 / 4

8. The F/M ratio in activated sludge relates food to:

• Flow
• Microorganisms
• Mixing
• Metering
• Microorganisms

F/M compares organic loading (food) to biomass (microorganisms).

9. A sudden drop in DO in the aeration basin may indicate:

• Excess alkalinity
• Low influent solids
• High organic loading
• High chlorine levels
• High organic loading

More organic matter increases oxygen demand, lowering DO.

10. Sludge bulking is commonly caused by:

• Excess chlorine
• Filamentous bacteria
• Low MLSS
• High DO
• Filamentous bacteria

Filamentous organisms hinder settling, causing bulking.

• Which laboratory test measures settleability?
• pH
• / 4