South Carolina Biological Wastewater
Operator Class C Exam Practice
Questions And Correct Answers (Verified
Answers) Plus Rationales 2026 Q&A |
Instant Download Pdf
Domain 1: Wastewater Fundamentals & Preliminary Treatment
Q1. What is the primary purpose of biological treatment in wastewater
plants?
A. Remove organic matter and nutrients using microorganisms
B. Remove large debris only
C. Chlorinate effluent
D. Increase flow rate
Correct ,,,answer,,,: A
Rationale: Biological treatment relies on microorganisms to break down organic
pollutants and remove nutrients like nitrogen and phosphorus .
Q2. Which parameter indicates the oxygen available for microorganisms in
biological treatment?
A. Dissolved oxygen (DO)
B. pH
C. Temperature
D. Alkalinity
Correct ,,,answer,,,: A
Rationale: Dissolved oxygen (DO) levels indicate how much oxygen is dissolved
in the water for aerobic microorganisms to metabolize waste .
,Q3. What is the primary function of a bar screen?
A. Remove large debris like rags and sticks
B. Remove dissolved nutrients
C. Settle solids
D. Aerate water
Correct ,,,answer,,,: A
Rationale: Bar screens prevent damage and clogging of downstream equipment by
removing large solids and debris during preliminary treatment .
Q4. What is the primary purpose of preliminary treatment?
A. Remove nutrients
B. Reduce organic matter
C. Remove large solids and debris
D. Disinfect wastewater
Correct ,,,answer,,,: C
Rationale: Preliminary treatment focuses on screening and grit removal to protect
downstream equipment and processes .
Q5. What is the primary purpose of a grit chamber?
A. Remove sand, gravel, and heavy solids
B. Remove organic matter
C. Increase DO
D. Reduce pH
Correct ,,,answer,,,: A
Rationale: Grit chambers remove inorganic heavy solids like sand and gravel,
preventing equipment wear and accumulation in downstream units .
Q6. How does a trickling filter treat wastewater?
A. Wastewater flows over biofilm-covered media to degrade organic matter
B. Uses chemicals to precipitate solids
C. Filters solids through sand
D. Disinfects with chlorine
Correct ,,,answer,,,: A
Rationale: Trickling filters allow wastewater to flow over microbial biofilms
attached to media, which degrade organic matter .
Q7. What is the primary function of a comminutor in preliminary treatment?
A. Remove floating debris
, B. Grind and shred solids
C. Settle out grit
D. Add chemicals
Correct ,,,answer,,,: B
Rationale: Comminutors chop up solids into smaller particles without removing
them from the flow, preventing clogging of downstream equipment .
Q8. What is the purpose of a bypass channel in preliminary treatment?
A. To increase flow velocity
B. To allow flow to bypass treatment units during maintenance or emergencies
C. To add chemicals
D. To sample wastewater
Correct ,,,answer,,,: B
Rationale: Bypass channels allow wastewater to flow around treatment units when
those units are out of service for maintenance or during emergency conditions .
Q9. Which method is NOT typically used for grit removal?
A. Aerated grit chamber
B. Horizontal flow grit chamber
C. Vortex grit removal system
D. Dissolved air flotation
Correct ,,,answer,,,: D
Rationale: Dissolved air flotation (DAF) is used for removing flocculated solids or
oil/grease, not for heavy grit removal .
Q10. What is the purpose of screening in preliminary treatment?
A. Remove dissolved gases
B. Remove large floating and suspended debris
C. Adjust pH
D. Disinfect pathogens
Correct ,,,answer,,,: B
Rationale: Screening physically removes large objects (rags, sticks, plastics) and
debris to protect downstream equipment from damage or clogging .
Operator Class C Exam Practice
Questions And Correct Answers (Verified
Answers) Plus Rationales 2026 Q&A |
Instant Download Pdf
Domain 1: Wastewater Fundamentals & Preliminary Treatment
Q1. What is the primary purpose of biological treatment in wastewater
plants?
A. Remove organic matter and nutrients using microorganisms
B. Remove large debris only
C. Chlorinate effluent
D. Increase flow rate
Correct ,,,answer,,,: A
Rationale: Biological treatment relies on microorganisms to break down organic
pollutants and remove nutrients like nitrogen and phosphorus .
Q2. Which parameter indicates the oxygen available for microorganisms in
biological treatment?
A. Dissolved oxygen (DO)
B. pH
C. Temperature
D. Alkalinity
Correct ,,,answer,,,: A
Rationale: Dissolved oxygen (DO) levels indicate how much oxygen is dissolved
in the water for aerobic microorganisms to metabolize waste .
,Q3. What is the primary function of a bar screen?
A. Remove large debris like rags and sticks
B. Remove dissolved nutrients
C. Settle solids
D. Aerate water
Correct ,,,answer,,,: A
Rationale: Bar screens prevent damage and clogging of downstream equipment by
removing large solids and debris during preliminary treatment .
Q4. What is the primary purpose of preliminary treatment?
A. Remove nutrients
B. Reduce organic matter
C. Remove large solids and debris
D. Disinfect wastewater
Correct ,,,answer,,,: C
Rationale: Preliminary treatment focuses on screening and grit removal to protect
downstream equipment and processes .
Q5. What is the primary purpose of a grit chamber?
A. Remove sand, gravel, and heavy solids
B. Remove organic matter
C. Increase DO
D. Reduce pH
Correct ,,,answer,,,: A
Rationale: Grit chambers remove inorganic heavy solids like sand and gravel,
preventing equipment wear and accumulation in downstream units .
Q6. How does a trickling filter treat wastewater?
A. Wastewater flows over biofilm-covered media to degrade organic matter
B. Uses chemicals to precipitate solids
C. Filters solids through sand
D. Disinfects with chlorine
Correct ,,,answer,,,: A
Rationale: Trickling filters allow wastewater to flow over microbial biofilms
attached to media, which degrade organic matter .
Q7. What is the primary function of a comminutor in preliminary treatment?
A. Remove floating debris
, B. Grind and shred solids
C. Settle out grit
D. Add chemicals
Correct ,,,answer,,,: B
Rationale: Comminutors chop up solids into smaller particles without removing
them from the flow, preventing clogging of downstream equipment .
Q8. What is the purpose of a bypass channel in preliminary treatment?
A. To increase flow velocity
B. To allow flow to bypass treatment units during maintenance or emergencies
C. To add chemicals
D. To sample wastewater
Correct ,,,answer,,,: B
Rationale: Bypass channels allow wastewater to flow around treatment units when
those units are out of service for maintenance or during emergency conditions .
Q9. Which method is NOT typically used for grit removal?
A. Aerated grit chamber
B. Horizontal flow grit chamber
C. Vortex grit removal system
D. Dissolved air flotation
Correct ,,,answer,,,: D
Rationale: Dissolved air flotation (DAF) is used for removing flocculated solids or
oil/grease, not for heavy grit removal .
Q10. What is the purpose of screening in preliminary treatment?
A. Remove dissolved gases
B. Remove large floating and suspended debris
C. Adjust pH
D. Disinfect pathogens
Correct ,,,answer,,,: B
Rationale: Screening physically removes large objects (rags, sticks, plastics) and
debris to protect downstream equipment from damage or clogging .
