Nevada Water Reclamation Operator Exam
Newest (2025 - 2026 Update) From Real
Past Papers Questions – A Set Of 100 Most
Common Exam Frequently Tested
Questions And Answers In Details 100%
Verified Exam Highly Recommendable For
Grade A+
1. The primary purpose of preliminary treatment at a wastewater reclamation
facility is to:
A. Remove dissolved nutrients
B. Remove large debris and grit
C. Eliminate pathogens
D. Remove dissolved oxygen
Answer: B. Remove large debris and grit
Explanation: Preliminary treatment protects downstream equipment by removing
rags, sticks, plastics, sand, gravel, and other large materials before biological
treatment.
2. Which process primarily removes settleable solids from wastewater?
A. Disinfection
B. Chlorination
C. Primary clarification
,D. Aeration
Answer: C. Primary clarification
Explanation: Primary clarifiers allow heavier solids to settle while floating
materials are skimmed from the surface, significantly reducing suspended solids.
3. Activated sludge microorganisms require which condition for effective
treatment?
A. High salinity
B. Adequate dissolved oxygen
C. Complete darkness
D. Zero organic matter
Answer: B. Adequate dissolved oxygen
Explanation: Aerobic microorganisms consume organic pollutants efficiently only
when sufficient dissolved oxygen is maintained.
4. Excessive sludge age in an activated sludge system is most likely to result in:
A. Young, rapidly growing biomass
B. Increased sludge stabilization
C. Immediate loss of disinfection
D. Increased grit production
Answer: B. Increased sludge stabilization
Explanation: Older sludge contains microorganisms that have consumed much of
the available food and become more stabilized through endogenous respiration.
5. Biochemical Oxygen Demand (BOD) is a measure of:
A. Chlorine concentration
B. Organic matter requiring oxygen for biological decomposition
,C. Total dissolved solids only
D. Water hardness
Answer: B. Organic matter requiring oxygen for biological decomposition
Explanation: BOD estimates the amount of oxygen microorganisms need to break
down biodegradable organic material.
6. What is the primary function of a secondary clarifier?
A. Add chlorine
B. Separate biological solids from treated wastewater
C. Remove grit
D. Measure pH
Answer: B. Separate biological solids from treated wastewater
Explanation: Secondary clarifiers allow activated sludge to settle so treated
effluent can leave the basin while settled biomass is recycled or wasted.
7. A low dissolved oxygen concentration in the aeration basin may cause:
A. Improved nitrification
B. Odor production and poor treatment
C. Lower sludge volume
D. Reduced microbial activity only during winter
Answer: B. Odor production and poor treatment
Explanation: Insufficient oxygen encourages undesirable biological conditions,
reduces treatment efficiency, and may create septic odors.
8. Return activated sludge (RAS) is primarily used to:
A. Increase chlorine residual
B. Return settled microorganisms to the aeration basin
, C. Remove phosphorus chemically
D. Increase influent flow
Answer: B. Return settled microorganisms to the aeration basin
Explanation: Recycling settled biomass maintains an adequate microbial
population for continuous biological treatment.
9. Which laboratory test is commonly used to estimate suspended solids in
wastewater?
A. BOD
B. Total Suspended Solids (TSS)
C. Alkalinity
D. Conductivity
Answer: B. Total Suspended Solids (TSS)
Explanation: TSS measures the concentration of particles suspended in
wastewater and is a key indicator of treatment performance.
10.Why is pH important in biological wastewater treatment?
A. It determines pipe diameter.
B. It affects microorganism activity.
C. It measures chlorine demand.
D. It controls grit removal.
Answer: B. It affects microorganism activity.
Explanation: Most treatment microorganisms perform best within an appropriate
pH range. Extreme pH levels can inhibit biological activity and reduce treatment
efficiency.
Fifty original multiple-choice questions with answers and explanations are too
long to fit within a single ChatGPT response.
Newest (2025 - 2026 Update) From Real
Past Papers Questions – A Set Of 100 Most
Common Exam Frequently Tested
Questions And Answers In Details 100%
Verified Exam Highly Recommendable For
Grade A+
1. The primary purpose of preliminary treatment at a wastewater reclamation
facility is to:
A. Remove dissolved nutrients
B. Remove large debris and grit
C. Eliminate pathogens
D. Remove dissolved oxygen
Answer: B. Remove large debris and grit
Explanation: Preliminary treatment protects downstream equipment by removing
rags, sticks, plastics, sand, gravel, and other large materials before biological
treatment.
2. Which process primarily removes settleable solids from wastewater?
A. Disinfection
B. Chlorination
C. Primary clarification
,D. Aeration
Answer: C. Primary clarification
Explanation: Primary clarifiers allow heavier solids to settle while floating
materials are skimmed from the surface, significantly reducing suspended solids.
3. Activated sludge microorganisms require which condition for effective
treatment?
A. High salinity
B. Adequate dissolved oxygen
C. Complete darkness
D. Zero organic matter
Answer: B. Adequate dissolved oxygen
Explanation: Aerobic microorganisms consume organic pollutants efficiently only
when sufficient dissolved oxygen is maintained.
4. Excessive sludge age in an activated sludge system is most likely to result in:
A. Young, rapidly growing biomass
B. Increased sludge stabilization
C. Immediate loss of disinfection
D. Increased grit production
Answer: B. Increased sludge stabilization
Explanation: Older sludge contains microorganisms that have consumed much of
the available food and become more stabilized through endogenous respiration.
5. Biochemical Oxygen Demand (BOD) is a measure of:
A. Chlorine concentration
B. Organic matter requiring oxygen for biological decomposition
,C. Total dissolved solids only
D. Water hardness
Answer: B. Organic matter requiring oxygen for biological decomposition
Explanation: BOD estimates the amount of oxygen microorganisms need to break
down biodegradable organic material.
6. What is the primary function of a secondary clarifier?
A. Add chlorine
B. Separate biological solids from treated wastewater
C. Remove grit
D. Measure pH
Answer: B. Separate biological solids from treated wastewater
Explanation: Secondary clarifiers allow activated sludge to settle so treated
effluent can leave the basin while settled biomass is recycled or wasted.
7. A low dissolved oxygen concentration in the aeration basin may cause:
A. Improved nitrification
B. Odor production and poor treatment
C. Lower sludge volume
D. Reduced microbial activity only during winter
Answer: B. Odor production and poor treatment
Explanation: Insufficient oxygen encourages undesirable biological conditions,
reduces treatment efficiency, and may create septic odors.
8. Return activated sludge (RAS) is primarily used to:
A. Increase chlorine residual
B. Return settled microorganisms to the aeration basin
, C. Remove phosphorus chemically
D. Increase influent flow
Answer: B. Return settled microorganisms to the aeration basin
Explanation: Recycling settled biomass maintains an adequate microbial
population for continuous biological treatment.
9. Which laboratory test is commonly used to estimate suspended solids in
wastewater?
A. BOD
B. Total Suspended Solids (TSS)
C. Alkalinity
D. Conductivity
Answer: B. Total Suspended Solids (TSS)
Explanation: TSS measures the concentration of particles suspended in
wastewater and is a key indicator of treatment performance.
10.Why is pH important in biological wastewater treatment?
A. It determines pipe diameter.
B. It affects microorganism activity.
C. It measures chlorine demand.
D. It controls grit removal.
Answer: B. It affects microorganism activity.
Explanation: Most treatment microorganisms perform best within an appropriate
pH range. Extreme pH levels can inhibit biological activity and reduce treatment
efficiency.
Fifty original multiple-choice questions with answers and explanations are too
long to fit within a single ChatGPT response.
