Page 1 of 102
South Dakota Wastewater Treatment Operator Class II Practice
ACTUAL EXAM QUESTIONS AND CORRECT VERIFIED
SOLUTIONS LATEST UPDATE THIS YEAR – JUST RELEASED
South Dakota Wastewater Treatment Operator Class II Practice Exam
This comprehensive practice exam is designed for the South Dakota Wastewater Treatment
Operator Class II certification, based on DANR requirements and ABC standardized testing .
Exam Domains (Class II Level)
Based on ABC standardized testing and SD DANR requirements, the Class II exam covers:
Preliminary & Primary Treatment – Screening, grit removal, sedimentation
Secondary Treatment (Activated Sludge) – MLSS, RAS/WAS, F/M ratio, SVI
Secondary Treatment (Fixed Film) – Trickling filters, RBCs
Tertiary Treatment & Disinfection – Filtration, chlorination, dechlorination, UV
Solids Handling – Thickening, digestion, dewatering
Laboratory & Process Control – BOD, TSS, pH, DO, settleability
Pumps, Motors, & Maintenance – Centrifugal pumps, preventive maintenance
Safety & Regulations – Confined space, H₂S, lockout/tagout, NPDES
Practice Questions (1-100)
Domain 1: Preliminary & Primary Treatment (Questions 1-15)
, Page 2 of 102
1. What is the primary purpose of a bar screen in a wastewater treatment plant?
A) Remove grit and sand
B) Remove large solids and debris
C) Remove dissolved organic matter
D) Equalize flow
Answer: B
Rationale: Bar screens physically remove large solids (rags, sticks, plastics) to protect
downstream equipment from damage or clogging.
2. A grit channel is designed to maintain what flow velocity to settle grit while keeping
organics suspended?
A) 0.5-0.8 ft/s
B) 1.0-1.5 ft/s
C) 2.0-3.0 ft/s
D) 4.0-5.0 ft/s
Answer: B
*Rationale: Grit channels maintain a velocity of approximately 1.0-1.5 ft/s to allow heavier grit
particles to settle while keeping lighter organic solids suspended.*
, Page 3 of 102
3. What is the typical detention time for a primary clarifier in a municipal wastewater plant?
A) 30-60 minutes
B) 1-2 hours
C) 2-4 hours
D) 6-12 hours
Answer: B
Rationale: Primary clarifiers typically have detention times of 1 to 2 hours, allowing sufficient
time for solids to settle by gravity.
4. A primary clarifier is operating with a sludge blanket depth of 4 feet. What is the most likely
consequence?
A) Improved effluent quality
B) Sludge carryover and increased effluent TSS
C) Reduced sludge pumping requirements
D) Increased BOD removal
Answer: B
Rationale: Excessive sludge blanket depth causes solids to carry over the effluent weir, increasing
TSS in the effluent and potentially causing septic conditions.
, Page 4 of 102
5. What is the expected TSS removal efficiency of a well-operated primary clarifier?
A) 20-30%
B) 40-50%
C) 50-70%
D) 80-90%
Answer: C
*Rationale: Primary clarifiers typically remove 50-70% of suspended solids and 25-40% of BOD.*
6. What instrument is used to measure sludge blanket depth in a clarifier?
A) pH meter
B) Dissolved oxygen probe
C) Sludge judge (core sampler)
D) Turbidimeter
Answer: C
Rationale: A sludge judge (clear plastic tube with a check valve) is lowered into the clarifier to
collect a core sample showing sludge blanket depth and condition.
7. What causes septic sludge in a primary clarifier?
South Dakota Wastewater Treatment Operator Class II Practice
ACTUAL EXAM QUESTIONS AND CORRECT VERIFIED
SOLUTIONS LATEST UPDATE THIS YEAR – JUST RELEASED
South Dakota Wastewater Treatment Operator Class II Practice Exam
This comprehensive practice exam is designed for the South Dakota Wastewater Treatment
Operator Class II certification, based on DANR requirements and ABC standardized testing .
Exam Domains (Class II Level)
Based on ABC standardized testing and SD DANR requirements, the Class II exam covers:
Preliminary & Primary Treatment – Screening, grit removal, sedimentation
Secondary Treatment (Activated Sludge) – MLSS, RAS/WAS, F/M ratio, SVI
Secondary Treatment (Fixed Film) – Trickling filters, RBCs
Tertiary Treatment & Disinfection – Filtration, chlorination, dechlorination, UV
Solids Handling – Thickening, digestion, dewatering
Laboratory & Process Control – BOD, TSS, pH, DO, settleability
Pumps, Motors, & Maintenance – Centrifugal pumps, preventive maintenance
Safety & Regulations – Confined space, H₂S, lockout/tagout, NPDES
Practice Questions (1-100)
Domain 1: Preliminary & Primary Treatment (Questions 1-15)
, Page 2 of 102
1. What is the primary purpose of a bar screen in a wastewater treatment plant?
A) Remove grit and sand
B) Remove large solids and debris
C) Remove dissolved organic matter
D) Equalize flow
Answer: B
Rationale: Bar screens physically remove large solids (rags, sticks, plastics) to protect
downstream equipment from damage or clogging.
2. A grit channel is designed to maintain what flow velocity to settle grit while keeping
organics suspended?
A) 0.5-0.8 ft/s
B) 1.0-1.5 ft/s
C) 2.0-3.0 ft/s
D) 4.0-5.0 ft/s
Answer: B
*Rationale: Grit channels maintain a velocity of approximately 1.0-1.5 ft/s to allow heavier grit
particles to settle while keeping lighter organic solids suspended.*
, Page 3 of 102
3. What is the typical detention time for a primary clarifier in a municipal wastewater plant?
A) 30-60 minutes
B) 1-2 hours
C) 2-4 hours
D) 6-12 hours
Answer: B
Rationale: Primary clarifiers typically have detention times of 1 to 2 hours, allowing sufficient
time for solids to settle by gravity.
4. A primary clarifier is operating with a sludge blanket depth of 4 feet. What is the most likely
consequence?
A) Improved effluent quality
B) Sludge carryover and increased effluent TSS
C) Reduced sludge pumping requirements
D) Increased BOD removal
Answer: B
Rationale: Excessive sludge blanket depth causes solids to carry over the effluent weir, increasing
TSS in the effluent and potentially causing septic conditions.
, Page 4 of 102
5. What is the expected TSS removal efficiency of a well-operated primary clarifier?
A) 20-30%
B) 40-50%
C) 50-70%
D) 80-90%
Answer: C
*Rationale: Primary clarifiers typically remove 50-70% of suspended solids and 25-40% of BOD.*
6. What instrument is used to measure sludge blanket depth in a clarifier?
A) pH meter
B) Dissolved oxygen probe
C) Sludge judge (core sampler)
D) Turbidimeter
Answer: C
Rationale: A sludge judge (clear plastic tube with a check valve) is lowered into the clarifier to
collect a core sample showing sludge blanket depth and condition.
7. What causes septic sludge in a primary clarifier?
