SOUTH DAKOTA WASTEWATER TREATMENT OPERATOR
CLASS II EXAMINATION COMPLETE QUESTIONS AND
DETAILED SOLUTIONS LATEST UPDATE THIS YEAR JUST
RELEASED
Tested Coverage Areas (Short Summary)
1. Wastewater Treatment Fundamentals – Flow characteristics, wastewater composition, treatment
objectives, and regulatory requirements.
2. Primary Treatment Processes – Screening, grit removal, primary clarifiers, sludge collection, and
operational troubleshooting.
3. Secondary (Biological) Treatment – Activated sludge, oxidation ditches, lagoons, trickling filters, RBCs,
and biological nutrient removal.
4. Disinfection & Effluent Quality – Chlorination, dechlorination, UV systems, pathogen reduction, and
permit compliance.
5. Sludge/Biosolids Processing – Thickening, digestion, dewatering, stabilization, disposal, and biosolids
regulations.
6. Laboratory Testing & Process Control – BOD, TSS, DO, pH, alkalinity, MLSS, MCRT, SVI, settleability, and
sampling techniques.
7. Equipment Operation & Maintenance – Pumps, blowers, valves, motors, instrumentation, preventive
maintenance, and troubleshooting.
8. Safety & Emergency Response – Confined spaces, lockout/tagout, chemical handling, PPE, gas detection,
and emergency procedures.
9. Collection Systems & Hydraulic Principles – Sewer systems, infiltration/inflow, lift stations, flow
measurement, and hydraulics.
10. Environmental Regulations & Operator Responsibilities – NPDES permits, recordkeeping, reporting,
ethics, and environmental protection.
South Dakota Wastewater Treatment Operator Class II Examination
Question 1
Which wastewater treatment process primarily removes large floating
debris before wastewater enters downstream treatment units, protecting
pumps and mechanical equipment from excessive wear and damage?
A. Secondary clarification
,B. Screening
C. Activated sludge aeration
D. Chlorination
Answer: B. Screening
Rationale: Screening removes sticks, rags, plastics, and other large debris
before treatment continues. This protects downstream pumps, valves, and
other equipment while improving overall plant reliability and reducing
maintenance costs.
Question 2
An operator observes dissolved oxygen levels consistently below 1.0 mg/L in
an activated sludge aeration basin. Which operational concern should
receive the highest priority because of its effect on biological treatment
performance?
A. Increased sludge drying
B. Poor biological oxidation
C. Improved nitrification
D. Faster sedimentation
Answer: B. Poor biological oxidation
Rationale: Low dissolved oxygen limits aerobic microorganisms responsible
for oxidizing organic matter. This decreases treatment efficiency, increases
BOD in the effluent, and may create undesirable odors and poor sludge
settling.
,Question 3
What is the primary purpose of maintaining adequate mixed liquor
suspended solids (MLSS) concentrations within an activated sludge aeration
basin during normal wastewater treatment operations?
A. Increase chlorine demand
B. Maintain an active microbial population
C. Reduce grit accumulation
D. Eliminate primary treatment
Answer: B. Maintain an active microbial population
Rationale: MLSS represents microorganisms and suspended solids that
biologically degrade pollutants. Proper concentrations ensure efficient
treatment, stable operation, and consistent effluent quality while
preventing process upsets.
Question 4
Which laboratory analysis directly measures the amount of oxygen
microorganisms require to biologically decompose organic matter contained
within a wastewater sample under standardized testing conditions?
A. Total suspended solids
B. Biochemical oxygen demand
C. Alkalinity
D. Conductivity
Answer: B. Biochemical oxygen demand
, Rationale: BOD measures biodegradable organic pollution by determining
oxygen consumed by microorganisms during decomposition over a specified
incubation period, commonly five days.
Question 5
A wastewater treatment operator notices sludge rising to the surface of a
secondary clarifier several hours after settling. Which condition most likely
explains this observation?
A. Excessive chlorination
B. Denitrification within settled sludge
C. High grit loading
D. Excessive screening
Answer: B. Denitrification within settled sludge
Rationale: Nitrogen gas produced during denitrification can become trapped
in sludge, causing it to float. Prompt sludge removal helps minimize this
condition.
Question 6
Why is maintaining proper sludge age important in activated sludge
treatment systems designed for reliable organic matter removal and
nitrification?
A. It determines bar screen spacing.
B. It maintains a healthy microbial population.
CLASS II EXAMINATION COMPLETE QUESTIONS AND
DETAILED SOLUTIONS LATEST UPDATE THIS YEAR JUST
RELEASED
Tested Coverage Areas (Short Summary)
1. Wastewater Treatment Fundamentals – Flow characteristics, wastewater composition, treatment
objectives, and regulatory requirements.
2. Primary Treatment Processes – Screening, grit removal, primary clarifiers, sludge collection, and
operational troubleshooting.
3. Secondary (Biological) Treatment – Activated sludge, oxidation ditches, lagoons, trickling filters, RBCs,
and biological nutrient removal.
4. Disinfection & Effluent Quality – Chlorination, dechlorination, UV systems, pathogen reduction, and
permit compliance.
5. Sludge/Biosolids Processing – Thickening, digestion, dewatering, stabilization, disposal, and biosolids
regulations.
6. Laboratory Testing & Process Control – BOD, TSS, DO, pH, alkalinity, MLSS, MCRT, SVI, settleability, and
sampling techniques.
7. Equipment Operation & Maintenance – Pumps, blowers, valves, motors, instrumentation, preventive
maintenance, and troubleshooting.
8. Safety & Emergency Response – Confined spaces, lockout/tagout, chemical handling, PPE, gas detection,
and emergency procedures.
9. Collection Systems & Hydraulic Principles – Sewer systems, infiltration/inflow, lift stations, flow
measurement, and hydraulics.
10. Environmental Regulations & Operator Responsibilities – NPDES permits, recordkeeping, reporting,
ethics, and environmental protection.
South Dakota Wastewater Treatment Operator Class II Examination
Question 1
Which wastewater treatment process primarily removes large floating
debris before wastewater enters downstream treatment units, protecting
pumps and mechanical equipment from excessive wear and damage?
A. Secondary clarification
,B. Screening
C. Activated sludge aeration
D. Chlorination
Answer: B. Screening
Rationale: Screening removes sticks, rags, plastics, and other large debris
before treatment continues. This protects downstream pumps, valves, and
other equipment while improving overall plant reliability and reducing
maintenance costs.
Question 2
An operator observes dissolved oxygen levels consistently below 1.0 mg/L in
an activated sludge aeration basin. Which operational concern should
receive the highest priority because of its effect on biological treatment
performance?
A. Increased sludge drying
B. Poor biological oxidation
C. Improved nitrification
D. Faster sedimentation
Answer: B. Poor biological oxidation
Rationale: Low dissolved oxygen limits aerobic microorganisms responsible
for oxidizing organic matter. This decreases treatment efficiency, increases
BOD in the effluent, and may create undesirable odors and poor sludge
settling.
,Question 3
What is the primary purpose of maintaining adequate mixed liquor
suspended solids (MLSS) concentrations within an activated sludge aeration
basin during normal wastewater treatment operations?
A. Increase chlorine demand
B. Maintain an active microbial population
C. Reduce grit accumulation
D. Eliminate primary treatment
Answer: B. Maintain an active microbial population
Rationale: MLSS represents microorganisms and suspended solids that
biologically degrade pollutants. Proper concentrations ensure efficient
treatment, stable operation, and consistent effluent quality while
preventing process upsets.
Question 4
Which laboratory analysis directly measures the amount of oxygen
microorganisms require to biologically decompose organic matter contained
within a wastewater sample under standardized testing conditions?
A. Total suspended solids
B. Biochemical oxygen demand
C. Alkalinity
D. Conductivity
Answer: B. Biochemical oxygen demand
, Rationale: BOD measures biodegradable organic pollution by determining
oxygen consumed by microorganisms during decomposition over a specified
incubation period, commonly five days.
Question 5
A wastewater treatment operator notices sludge rising to the surface of a
secondary clarifier several hours after settling. Which condition most likely
explains this observation?
A. Excessive chlorination
B. Denitrification within settled sludge
C. High grit loading
D. Excessive screening
Answer: B. Denitrification within settled sludge
Rationale: Nitrogen gas produced during denitrification can become trapped
in sludge, causing it to float. Prompt sludge removal helps minimize this
condition.
Question 6
Why is maintaining proper sludge age important in activated sludge
treatment systems designed for reliable organic matter removal and
nitrification?
A. It determines bar screen spacing.
B. It maintains a healthy microbial population.
