VIRGINIA WASTEWATER WORKS OPERATOR CLASS 3
EXAMINATION COMPLETE QUESTIONS AND DETAILED
SOLUTIONS LATEST UPDATE THIS YEAR JUST RELEASED
Exam Coverage Areas
1. Wastewater Treatment Fundamentals
o Characteristics of wastewater, flow patterns, treatment objectives, and terminology.
2. Primary Treatment Processes
o Screening, grit removal, primary clarification, scum removal, and sedimentation
principles.
3. Secondary Biological Treatment
o Activated sludge, oxidation ditches, trickling filters, RBCs, aeration systems, and
microorganisms.
4. Disinfection and Effluent Quality
o Chlorination, dechlorination, UV systems, contact time, and permit compliance.
5. Sludge Processing and Biosolids
o Thickening, digestion, dewatering, stabilization, disposal, and handling safety.
6. Laboratory Testing and Process Control
o BOD, COD, TSS, pH, dissolved oxygen, settleability, nutrient testing, and sampling
procedures.
7. Pumps, Motors, and Mechanical Equipment
o Pump operation, preventive maintenance, valves, blowers, bearings, and
troubleshooting.
8. Safety and OSHA Requirements
o Confined space entry, lockout/tagout, PPE, hazardous chemicals, electrical safety, and
emergency response.
9. Virginia Regulations and Operator Responsibilities
o Permit requirements, recordkeeping, reporting, environmental protection, and operator
ethics.
10. Mathematics and Operational Calculations
Flow calculations, detention time, loading rates, chemical dosage, percent removal, and unit
conversions.
Question 1
Which treatment process primarily removes large debris before wastewater
reaches downstream treatment units and protects pumps from damage?
,A. Secondary clarification
B. Screening
C. Chlorination
D. Sludge digestion
Answer: B
Rationale: Screening removes rags, sticks, plastics, and other large materials that
could damage pumps and interfere with downstream equipment. It is normally
the first treatment process.
Question 2
Which wastewater characteristic measures the amount of oxygen microorganisms
require to biologically decompose organic matter over five days?
A. Total Suspended Solids
B. pH
C. Biochemical Oxygen Demand
D. Turbidity
Answer: C
Rationale: Biochemical Oxygen Demand (BOD₅) measures biodegradable organic
pollution and is one of the most important indicators of wastewater treatment
performance.
Question 3
Why is grit removed early during wastewater treatment before wastewater
enters pumps and biological treatment processes?
,A. To disinfect wastewater
B. To increase dissolved oxygen
C. To prevent abrasion and equipment wear
D. To remove dissolved nutrients
Answer: C
Rationale: Grit consists of sand, gravel, coffee grounds, and similar heavy
materials that cause excessive wear on pumps, pipes, and mechanical equipment
if not removed.
Question 4
Which unit process primarily allows heavier suspended solids to settle while
lighter materials float for removal?
A. Aeration basin
B. Primary clarifier
C. Chlorine contact tank
D. Digester
Answer: B
Rationale: Primary clarifiers remove settleable solids by gravity while skimming
floating grease and scum from the water surface.
Question 5
What is the primary purpose of supplying oxygen within an activated sludge
aeration basin during normal wastewater treatment?
, A. Destroy viruses chemically
B. Support aerobic microorganisms
C. Remove grit particles
D. Increase alkalinity
Answer: B
Rationale: Aerobic microorganisms require dissolved oxygen to metabolize
organic pollutants and maintain efficient biological treatment.
Question 6
Which laboratory test most directly measures suspended particles remaining
within treated wastewater before discharge?
A. Dissolved oxygen
B. Total Suspended Solids
C. Alkalinity
D. Conductivity
Answer: B
Rationale: Total Suspended Solids (TSS) indicates the amount of particulate
material remaining in wastewater after treatment.
Question 7
Why should dissolved oxygen levels remain adequate throughout an activated
sludge aeration basin during normal operation?
A. To improve screening efficiency
EXAMINATION COMPLETE QUESTIONS AND DETAILED
SOLUTIONS LATEST UPDATE THIS YEAR JUST RELEASED
Exam Coverage Areas
1. Wastewater Treatment Fundamentals
o Characteristics of wastewater, flow patterns, treatment objectives, and terminology.
2. Primary Treatment Processes
o Screening, grit removal, primary clarification, scum removal, and sedimentation
principles.
3. Secondary Biological Treatment
o Activated sludge, oxidation ditches, trickling filters, RBCs, aeration systems, and
microorganisms.
4. Disinfection and Effluent Quality
o Chlorination, dechlorination, UV systems, contact time, and permit compliance.
5. Sludge Processing and Biosolids
o Thickening, digestion, dewatering, stabilization, disposal, and handling safety.
6. Laboratory Testing and Process Control
o BOD, COD, TSS, pH, dissolved oxygen, settleability, nutrient testing, and sampling
procedures.
7. Pumps, Motors, and Mechanical Equipment
o Pump operation, preventive maintenance, valves, blowers, bearings, and
troubleshooting.
8. Safety and OSHA Requirements
o Confined space entry, lockout/tagout, PPE, hazardous chemicals, electrical safety, and
emergency response.
9. Virginia Regulations and Operator Responsibilities
o Permit requirements, recordkeeping, reporting, environmental protection, and operator
ethics.
10. Mathematics and Operational Calculations
Flow calculations, detention time, loading rates, chemical dosage, percent removal, and unit
conversions.
Question 1
Which treatment process primarily removes large debris before wastewater
reaches downstream treatment units and protects pumps from damage?
,A. Secondary clarification
B. Screening
C. Chlorination
D. Sludge digestion
Answer: B
Rationale: Screening removes rags, sticks, plastics, and other large materials that
could damage pumps and interfere with downstream equipment. It is normally
the first treatment process.
Question 2
Which wastewater characteristic measures the amount of oxygen microorganisms
require to biologically decompose organic matter over five days?
A. Total Suspended Solids
B. pH
C. Biochemical Oxygen Demand
D. Turbidity
Answer: C
Rationale: Biochemical Oxygen Demand (BOD₅) measures biodegradable organic
pollution and is one of the most important indicators of wastewater treatment
performance.
Question 3
Why is grit removed early during wastewater treatment before wastewater
enters pumps and biological treatment processes?
,A. To disinfect wastewater
B. To increase dissolved oxygen
C. To prevent abrasion and equipment wear
D. To remove dissolved nutrients
Answer: C
Rationale: Grit consists of sand, gravel, coffee grounds, and similar heavy
materials that cause excessive wear on pumps, pipes, and mechanical equipment
if not removed.
Question 4
Which unit process primarily allows heavier suspended solids to settle while
lighter materials float for removal?
A. Aeration basin
B. Primary clarifier
C. Chlorine contact tank
D. Digester
Answer: B
Rationale: Primary clarifiers remove settleable solids by gravity while skimming
floating grease and scum from the water surface.
Question 5
What is the primary purpose of supplying oxygen within an activated sludge
aeration basin during normal wastewater treatment?
, A. Destroy viruses chemically
B. Support aerobic microorganisms
C. Remove grit particles
D. Increase alkalinity
Answer: B
Rationale: Aerobic microorganisms require dissolved oxygen to metabolize
organic pollutants and maintain efficient biological treatment.
Question 6
Which laboratory test most directly measures suspended particles remaining
within treated wastewater before discharge?
A. Dissolved oxygen
B. Total Suspended Solids
C. Alkalinity
D. Conductivity
Answer: B
Rationale: Total Suspended Solids (TSS) indicates the amount of particulate
material remaining in wastewater after treatment.
Question 7
Why should dissolved oxygen levels remain adequate throughout an activated
sludge aeration basin during normal operation?
A. To improve screening efficiency
