Wastewater Operator Certification Exam
Questions 2026/2027 | Wastewater
Operations Study Guide | Operator
Practice Test and Certification Exam
Preparation
Description: This comprehensive revision set contains 200 multiple-choice questions
(MCQs) designed to prepare candidates for Wastewater Operator Certification
Exams (2026/2027) . It covers wastewater treatment principles, collection systems,
preliminary/primary/secondary treatment, disinfection, sludge handling,
laboratory testing, safety, regulations, and math calculations. Each question
includes the correct answer marked with ✅.
Keywords: Wastewater Operator Certification, Wastewater Treatment, Operator Practice
Test, Study Guide 2026, Study Guide 2027, Collection Systems, Primary Treatment,
Secondary Treatment, Activated Sludge, Trickling Filters, Disinfection, Chlorination, UV,
Sludge Digestion, Biosolids, Laboratory Testing, BOD, TSS, pH, Safety, OSHA, NPDES,
EPA, Math Calculations, Exam Preparation.
Section 1: Wastewater Basics and Preliminary Treatment
(Questions 1–40)
1. What is the primary purpose of wastewater treatment?
A. To generate electricity
B. To protect public health and the environment ✅
,C. To produce drinking water
D. To create fertilizer only
2. Which of the following is a physical characteristic of wastewater?
A. pH
B. BOD
C. Temperature ✅
D. Alkalinity
3. What does BOD stand for?
A. Biological Oxygen Demand
B. Biochemical Oxygen Demand ✅
C. Basic Oxygen Deficiency
D. Bacterial Oxygen Depletion
4. What does TSS stand for?
A. Total Soluble Solids
B. Total Suspended Solids ✅
C. Toxic Synthetic Sludge
D. Total Sewage Sludge
5. Which gas is produced during anaerobic decomposition?
A. Oxygen
B. Nitrogen
C. Methane ✅
D. Helium
6. What is the typical pH range of raw domestic wastewater?
A. 2–4
B. 6–8 ✅
C. 9–11
D. 12–14
,7. What is the main purpose of screening in wastewater treatment?
A. Remove dissolved solids
B. Remove large debris and rags ✅
C. Kill bacteria
D. Add oxygen
8. What is a bar screen?
A. A chemical filter
B. A device with parallel bars to catch large solids ✅
C. A type of pump
D. A disinfection unit
9. What is grit?
A. Dissolved organic matter
B. Heavy inorganic particles like sand and gravel ✅
C. Floating grease
D. Biological floc
10. Why is grit removed early in treatment?
A. To prevent wear on pumps and equipment ✅
B. To increase BOD
C. To add nutrients
D. To improve disinfection
11. What is a comminutor?
A. A device that grinds solids into smaller pieces ✅
B. A settling tank
C. A chlorinator
D. A sludge digester
12. What is the purpose of a grit chamber?
A. Remove dissolved gases
B. Settle out heavy inorganic solids ✅
, C. Kill pathogens
D. Add chlorine
13. Which flow measurement device is commonly used in wastewater plants?
A. Thermometer
B. Parshall flume ✅
C. pH meter
D. Turbidimeter
14. What is influent?
A. Treated water leaving the plant
B. Water entering the treatment plant ✅
C. Sludge leaving the digester
D. Recycled activated sludge
15. What is effluent?
A. Water entering the plant
B. Treated water leaving the plant ✅
C. Raw sewage
D. Digested sludge
16. What is infiltration?
A. Groundwater entering sewers through cracks ✅
B. Stormwater entering sewers
C. Sewage leaking out of pipes
D. Chemical addition
17. What is inflow?
A. Groundwater entering sewers
B. Stormwater entering sewers through direct connections ✅
C. Sewage leaking out
D. Treated water discharge
Questions 2026/2027 | Wastewater
Operations Study Guide | Operator
Practice Test and Certification Exam
Preparation
Description: This comprehensive revision set contains 200 multiple-choice questions
(MCQs) designed to prepare candidates for Wastewater Operator Certification
Exams (2026/2027) . It covers wastewater treatment principles, collection systems,
preliminary/primary/secondary treatment, disinfection, sludge handling,
laboratory testing, safety, regulations, and math calculations. Each question
includes the correct answer marked with ✅.
Keywords: Wastewater Operator Certification, Wastewater Treatment, Operator Practice
Test, Study Guide 2026, Study Guide 2027, Collection Systems, Primary Treatment,
Secondary Treatment, Activated Sludge, Trickling Filters, Disinfection, Chlorination, UV,
Sludge Digestion, Biosolids, Laboratory Testing, BOD, TSS, pH, Safety, OSHA, NPDES,
EPA, Math Calculations, Exam Preparation.
Section 1: Wastewater Basics and Preliminary Treatment
(Questions 1–40)
1. What is the primary purpose of wastewater treatment?
A. To generate electricity
B. To protect public health and the environment ✅
,C. To produce drinking water
D. To create fertilizer only
2. Which of the following is a physical characteristic of wastewater?
A. pH
B. BOD
C. Temperature ✅
D. Alkalinity
3. What does BOD stand for?
A. Biological Oxygen Demand
B. Biochemical Oxygen Demand ✅
C. Basic Oxygen Deficiency
D. Bacterial Oxygen Depletion
4. What does TSS stand for?
A. Total Soluble Solids
B. Total Suspended Solids ✅
C. Toxic Synthetic Sludge
D. Total Sewage Sludge
5. Which gas is produced during anaerobic decomposition?
A. Oxygen
B. Nitrogen
C. Methane ✅
D. Helium
6. What is the typical pH range of raw domestic wastewater?
A. 2–4
B. 6–8 ✅
C. 9–11
D. 12–14
,7. What is the main purpose of screening in wastewater treatment?
A. Remove dissolved solids
B. Remove large debris and rags ✅
C. Kill bacteria
D. Add oxygen
8. What is a bar screen?
A. A chemical filter
B. A device with parallel bars to catch large solids ✅
C. A type of pump
D. A disinfection unit
9. What is grit?
A. Dissolved organic matter
B. Heavy inorganic particles like sand and gravel ✅
C. Floating grease
D. Biological floc
10. Why is grit removed early in treatment?
A. To prevent wear on pumps and equipment ✅
B. To increase BOD
C. To add nutrients
D. To improve disinfection
11. What is a comminutor?
A. A device that grinds solids into smaller pieces ✅
B. A settling tank
C. A chlorinator
D. A sludge digester
12. What is the purpose of a grit chamber?
A. Remove dissolved gases
B. Settle out heavy inorganic solids ✅
, C. Kill pathogens
D. Add chlorine
13. Which flow measurement device is commonly used in wastewater plants?
A. Thermometer
B. Parshall flume ✅
C. pH meter
D. Turbidimeter
14. What is influent?
A. Treated water leaving the plant
B. Water entering the treatment plant ✅
C. Sludge leaving the digester
D. Recycled activated sludge
15. What is effluent?
A. Water entering the plant
B. Treated water leaving the plant ✅
C. Raw sewage
D. Digested sludge
16. What is infiltration?
A. Groundwater entering sewers through cracks ✅
B. Stormwater entering sewers
C. Sewage leaking out of pipes
D. Chemical addition
17. What is inflow?
A. Groundwater entering sewers
B. Stormwater entering sewers through direct connections ✅
C. Sewage leaking out
D. Treated water discharge
