Alabama Wastewater Operator Grade II
Exam Practice Questions And Correct
Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
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1. What is the primary purpose of preliminary treatment in a wastewater
treatment plant?
A. Remove dissolved nutrients
B. Remove large debris and grit
C. Destroy pathogens
D. Remove dissolved oxygen
Rationale: Preliminary treatment protects downstream equipment by
removing large solids, rags, sticks, and grit that could damage pumps and
clog pipes before biological treatment begins.
2. Which process is primarily responsible for removing biodegradable
organic matter in an activated sludge system?
,A. Chlorination
B. Sedimentation alone
C. Microbial metabolism
D. Filtration
Rationale: Microorganisms consume biodegradable organic material as
food, converting it into new cells, carbon dioxide, and water, thereby
reducing BOD.
3. What does BOD measure?
A. Amount of dissolved solids
B. Concentration of chlorine
C. Oxygen required by microorganisms to decompose organic matter
D. Nitrogen concentration
Rationale: Biochemical Oxygen Demand measures the oxygen
microorganisms require to biologically stabilize biodegradable organic
material over a specified period.
4. Excessive grease entering a wastewater plant is most likely to cause:
A. Improved settling
B. Increased dissolved oxygen
C. Clogging and operational problems
D. Increased chlorination efficiency
,Rationale: Grease accumulates in pipes, pumps, and treatment units,
reducing flow efficiency and interfering with biological treatment
processes.
5. Which structure is commonly used to measure open channel flow?
A. Venturi meter
B. Parshall flume
C. Pitot tube
D. Rotameter
Rationale: A Parshall flume accurately measures wastewater flow in open
channels while minimizing head loss and solids accumulation.
6. The primary function of a bar screen is to:
A. Remove dissolved solids
B. Remove large floating and suspended debris
C. Add oxygen
D. Remove ammonia
Rationale: Bar screens intercept large materials such as rags, plastics, and
sticks before they enter downstream treatment processes.
7. Which laboratory test is commonly used to estimate suspended
solids?
, A. COD
B. Alkalinity
C. Total Suspended Solids (TSS)
D. Hardness
Rationale: TSS measures particles retained on a filter and provides an
indication of suspended material in wastewater.
8. Primary clarifiers primarily remove:
A. Dissolved nutrients
B. Pathogens
C. Settleable and floatable solids
D. Dissolved oxygen
Rationale: Primary clarification removes solids that settle by gravity and
floatable materials such as grease and scum.
9. What is the primary purpose of aeration in activated sludge?
A. Increase pH
B. Reduce alkalinity
C. Supply oxygen for microorganisms
D. Remove chlorine
Rationale: Aeration provides oxygen needed by aerobic microorganisms to
metabolize organic pollutants efficiently.
Exam Practice Questions And Correct
Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
Download Pdf
1. What is the primary purpose of preliminary treatment in a wastewater
treatment plant?
A. Remove dissolved nutrients
B. Remove large debris and grit
C. Destroy pathogens
D. Remove dissolved oxygen
Rationale: Preliminary treatment protects downstream equipment by
removing large solids, rags, sticks, and grit that could damage pumps and
clog pipes before biological treatment begins.
2. Which process is primarily responsible for removing biodegradable
organic matter in an activated sludge system?
,A. Chlorination
B. Sedimentation alone
C. Microbial metabolism
D. Filtration
Rationale: Microorganisms consume biodegradable organic material as
food, converting it into new cells, carbon dioxide, and water, thereby
reducing BOD.
3. What does BOD measure?
A. Amount of dissolved solids
B. Concentration of chlorine
C. Oxygen required by microorganisms to decompose organic matter
D. Nitrogen concentration
Rationale: Biochemical Oxygen Demand measures the oxygen
microorganisms require to biologically stabilize biodegradable organic
material over a specified period.
4. Excessive grease entering a wastewater plant is most likely to cause:
A. Improved settling
B. Increased dissolved oxygen
C. Clogging and operational problems
D. Increased chlorination efficiency
,Rationale: Grease accumulates in pipes, pumps, and treatment units,
reducing flow efficiency and interfering with biological treatment
processes.
5. Which structure is commonly used to measure open channel flow?
A. Venturi meter
B. Parshall flume
C. Pitot tube
D. Rotameter
Rationale: A Parshall flume accurately measures wastewater flow in open
channels while minimizing head loss and solids accumulation.
6. The primary function of a bar screen is to:
A. Remove dissolved solids
B. Remove large floating and suspended debris
C. Add oxygen
D. Remove ammonia
Rationale: Bar screens intercept large materials such as rags, plastics, and
sticks before they enter downstream treatment processes.
7. Which laboratory test is commonly used to estimate suspended
solids?
, A. COD
B. Alkalinity
C. Total Suspended Solids (TSS)
D. Hardness
Rationale: TSS measures particles retained on a filter and provides an
indication of suspended material in wastewater.
8. Primary clarifiers primarily remove:
A. Dissolved nutrients
B. Pathogens
C. Settleable and floatable solids
D. Dissolved oxygen
Rationale: Primary clarification removes solids that settle by gravity and
floatable materials such as grease and scum.
9. What is the primary purpose of aeration in activated sludge?
A. Increase pH
B. Reduce alkalinity
C. Supply oxygen for microorganisms
D. Remove chlorine
Rationale: Aeration provides oxygen needed by aerobic microorganisms to
metabolize organic pollutants efficiently.
