SOUTH CAROLINA PHYSICAL/CHEMICAL WASTEWATER
OPERATOR CLASS C ACTUAL EXAM 2026-2027 COMPLETE
EXAM QUESTIONS AND CORRECT DETAILED ANSWERS
WITH RATIONALES/ 100% GUARANTEED PASS
1. What is the primary purpose of preliminary treatment in a physical/chemical wastewater plant?
a) To remove dissolved organic matter
b) To disinfect effluent
c) To remove large solids and grit
d) To adjust pH
*Correct answer: c) To remove large solids and grit
Rationale: Preliminary treatment removes debris (rags, sticks) and grit (sand, gravel) that could
damage pumps or interfere with downstream processes. Dissolved organics and disinfection occur
later.
2. Which chemical is most commonly used for phosphorus removal in physical/chemical treatment?
a) Chlorine
b) Sodium hydroxide
c) Alum (aluminum sulfate)
d) Polymer only
*Correct answer: c) Alum (aluminum sulfate)
Rationale: Alum coagulates phosphorus into insoluble precipitates. Chlorine is a disinfectant, sodium
hydroxide adjusts pH, and polymers aid flocculation but rarely remove phosphorus alone.
3. What does the term “coagulation” refer to in wastewater treatment?
a) Settling of solids by gravity
b) Destabilizing particles to allow agglomeration
c) Killing bacteria with UV light
d) Removing dissolved gases
*Correct answer: b) Destabilizing particles to allow agglomeration
,Rationale: Coagulation uses chemicals (e.g., alum, ferric chloride) to neutralize charges on suspended
particles, enabling them to clump together. Sedimentation and disinfection are separate steps.
4. A Class C operator in South Carolina must have at least how many hours of approved continuing
education units (CEUs) per renewal period?
a) 12 hours
b) 24 hours
c) 30 hours
d) 40 hours
*Correct answer: c) 30 hours
*Rationale: South Carolina requires 30 CEUs (3.0 CEU credits) per 3-year renewal period for Class C
wastewater operators, per SCDHEC regulations.*
5. What is the typical pH range required for effective coagulation with alum?
a) 4.5–5.5
b) *5.5–7.5*
c) 7.5–8.5
d) 8.5–10.0
*Correct answer: b) 5.5–7.5
Rationale: Alum works best in slightly acidic to neutral pH (5.5–7.5). Outside this range, solubility
increases and coagulation efficiency drops.
6. Which laboratory test measures the oxygen equivalent of organic matter in wastewater?
a) pH
b) Turbidity
c) Biochemical Oxygen Demand (BOD)
d) Temperature
*Correct answer: c) Biochemical Oxygen Demand (BOD)
Rationale: BOD measures oxygen consumed by microorganisms decomposing organic matter. pH and
turbidity are physical/chemical parameters, not direct oxygen demand.
7. In a physical/chemical plant, flocculation is designed to:
a) Disinfect effluent
b) Gather small particles into larger settleable flocs
c) Remove grit
d) Aerate wastewater
*Correct answer: b) Gather small particles into larger settleable flocs
, Rationale: After coagulation, flocculation uses gentle mixing to form larger flocs that settle rapidly.
Disinfection and grit removal are separate processes.
8. What is the maximum allowable chlorine residual in the effluent per South Carolina general permit
for most facilities?
a) 0.1 mg/L
b) *0.5 mg/L (total residual chlorine)*
c) 2.0 mg/L
d) 5.0 mg/L
*Correct answer: b) 0.5 mg/L (total residual chlorine)
*Rationale: SC regulations limit total residual chlorine to 0.5 mg/L (daily max) to protect aquatic life.
Dechlorination is often required.*
9. Which piece of safety equipment must be immediately available when working around chlorine?
a) Fire extinguisher
b) Self-contained breathing apparatus (SCBA)
c) Hard hat
d) Ear plugs
*Correct answer: b) Self-contained breathing apparatus (SCBA)
Rationale: Chlorine gas is highly toxic and can cause respiratory failure. SCBA provides breathable
air; other items do not protect against inhalation hazards.
10. What does “turbidity” measure in wastewater?
a) Dissolved oxygen concentration
b) Cloudiness caused by suspended particles
c) Alkalinity
d) Bacterial count
*Correct answer: b) Cloudiness caused by suspended particles
Rationale: Turbidity is an optical property indicating particle presence. High turbidity can interfere
with disinfection and indicate poor solids removal.
11. Which chemical is typically used for dechlorination?
a) Chlorine gas
b) Sodium bisulfite
c) Alum
d) Lime
*Correct answer: b) Sodium bisulfite
OPERATOR CLASS C ACTUAL EXAM 2026-2027 COMPLETE
EXAM QUESTIONS AND CORRECT DETAILED ANSWERS
WITH RATIONALES/ 100% GUARANTEED PASS
1. What is the primary purpose of preliminary treatment in a physical/chemical wastewater plant?
a) To remove dissolved organic matter
b) To disinfect effluent
c) To remove large solids and grit
d) To adjust pH
*Correct answer: c) To remove large solids and grit
Rationale: Preliminary treatment removes debris (rags, sticks) and grit (sand, gravel) that could
damage pumps or interfere with downstream processes. Dissolved organics and disinfection occur
later.
2. Which chemical is most commonly used for phosphorus removal in physical/chemical treatment?
a) Chlorine
b) Sodium hydroxide
c) Alum (aluminum sulfate)
d) Polymer only
*Correct answer: c) Alum (aluminum sulfate)
Rationale: Alum coagulates phosphorus into insoluble precipitates. Chlorine is a disinfectant, sodium
hydroxide adjusts pH, and polymers aid flocculation but rarely remove phosphorus alone.
3. What does the term “coagulation” refer to in wastewater treatment?
a) Settling of solids by gravity
b) Destabilizing particles to allow agglomeration
c) Killing bacteria with UV light
d) Removing dissolved gases
*Correct answer: b) Destabilizing particles to allow agglomeration
,Rationale: Coagulation uses chemicals (e.g., alum, ferric chloride) to neutralize charges on suspended
particles, enabling them to clump together. Sedimentation and disinfection are separate steps.
4. A Class C operator in South Carolina must have at least how many hours of approved continuing
education units (CEUs) per renewal period?
a) 12 hours
b) 24 hours
c) 30 hours
d) 40 hours
*Correct answer: c) 30 hours
*Rationale: South Carolina requires 30 CEUs (3.0 CEU credits) per 3-year renewal period for Class C
wastewater operators, per SCDHEC regulations.*
5. What is the typical pH range required for effective coagulation with alum?
a) 4.5–5.5
b) *5.5–7.5*
c) 7.5–8.5
d) 8.5–10.0
*Correct answer: b) 5.5–7.5
Rationale: Alum works best in slightly acidic to neutral pH (5.5–7.5). Outside this range, solubility
increases and coagulation efficiency drops.
6. Which laboratory test measures the oxygen equivalent of organic matter in wastewater?
a) pH
b) Turbidity
c) Biochemical Oxygen Demand (BOD)
d) Temperature
*Correct answer: c) Biochemical Oxygen Demand (BOD)
Rationale: BOD measures oxygen consumed by microorganisms decomposing organic matter. pH and
turbidity are physical/chemical parameters, not direct oxygen demand.
7. In a physical/chemical plant, flocculation is designed to:
a) Disinfect effluent
b) Gather small particles into larger settleable flocs
c) Remove grit
d) Aerate wastewater
*Correct answer: b) Gather small particles into larger settleable flocs
, Rationale: After coagulation, flocculation uses gentle mixing to form larger flocs that settle rapidly.
Disinfection and grit removal are separate processes.
8. What is the maximum allowable chlorine residual in the effluent per South Carolina general permit
for most facilities?
a) 0.1 mg/L
b) *0.5 mg/L (total residual chlorine)*
c) 2.0 mg/L
d) 5.0 mg/L
*Correct answer: b) 0.5 mg/L (total residual chlorine)
*Rationale: SC regulations limit total residual chlorine to 0.5 mg/L (daily max) to protect aquatic life.
Dechlorination is often required.*
9. Which piece of safety equipment must be immediately available when working around chlorine?
a) Fire extinguisher
b) Self-contained breathing apparatus (SCBA)
c) Hard hat
d) Ear plugs
*Correct answer: b) Self-contained breathing apparatus (SCBA)
Rationale: Chlorine gas is highly toxic and can cause respiratory failure. SCBA provides breathable
air; other items do not protect against inhalation hazards.
10. What does “turbidity” measure in wastewater?
a) Dissolved oxygen concentration
b) Cloudiness caused by suspended particles
c) Alkalinity
d) Bacterial count
*Correct answer: b) Cloudiness caused by suspended particles
Rationale: Turbidity is an optical property indicating particle presence. High turbidity can interfere
with disinfection and indicate poor solids removal.
11. Which chemical is typically used for dechlorination?
a) Chlorine gas
b) Sodium bisulfite
c) Alum
d) Lime
*Correct answer: b) Sodium bisulfite
