AK Wastewater Treatment Contractor
Exam Questions And Correct Answers
(Verified Answers) Plus Rationale2026
Q&A| Instant Download Pdf
1. What is the primary purpose of a wastewater treatment plant?
A. To generate electricity
B. To remove contaminants from water
C. To increase water hardness
D. To store water
B. To remove contaminants from water
Rationale: The main purpose of a wastewater treatment plant is to remove
physical, chemical, and biological contaminants from water to make it safe
for discharge or reuse.
2. Which of the following is considered a primary treatment process?
A. Activated sludge
B. Sedimentation
C. Chlorination
D. Trickling filter
B. Sedimentation
Rationale: Primary treatment involves physical processes like
sedimentation to remove suspended solids.
3. Secondary treatment in wastewater primarily targets:
A. Dissolved solids
B. Pathogens
, C. Organic matter
D. Heavy metals
C. Organic matter
Rationale: Secondary treatment uses biological processes to break down
organic matter.
4. What is the typical purpose of a grit chamber?
A. Remove dissolved chemicals
B. Settle heavy inorganic solids
C. Kill bacteria
D. Aerate water
B. Settle heavy inorganic solids
Rationale: Grit chambers remove sand, gravel, and other heavy particles to
prevent damage to downstream equipment.
5. Which bacteria are primarily responsible for breaking down organic
waste in activated sludge systems?
A. Anaerobic bacteria
B. Nitrifying bacteria
C. Heterotrophic bacteria
D. Sulfate-reducing bacteria
C. Heterotrophic bacteria
Rationale: Heterotrophic bacteria consume organic carbon compounds in
wastewater.
6. What is the main advantage of an aeration tank?
A. Reduces sludge production
B. Increases oxygen supply to microorganisms
C. Removes heavy metals
D. Reduces water temperature
B. Increases oxygen supply to microorganisms
Rationale: Aeration tanks provide oxygen needed for aerobic bacteria to
degrade organic matter.
, 7. Which process is used to remove nitrogen from wastewater?
A. Chlorination
B. Nitrification and denitrification
C. Flocculation
D. Sedimentation
B. Nitrification and denitrification
Rationale: Nitrogen is removed biologically through nitrification (ammonia
to nitrate) and denitrification (nitrate to nitrogen gas).
8. Which chemical is commonly used for disinfection in wastewater
treatment?
A. Sodium hydroxide
B. Chlorine
C. Ferric chloride
D. Calcium carbonate
B. Chlorine
Rationale: Chlorine is widely used for disinfection due to its ability to kill
pathogens.
9. In wastewater treatment, BOD stands for:
A. Biological Oxidation Demand
B. Biochemical Oxygen Demand
C. Basic Oxygen Density
D. Biochemical Organic Decomposition
B. Biochemical Oxygen Demand
Rationale: BOD measures the amount of dissolved oxygen needed by
microorganisms to decompose organic matter.
10. What is the function of a clarifier in wastewater treatment?
A. Aerate water
B. Remove solids by settling
C. Add nutrients
D. Neutralize pH
Exam Questions And Correct Answers
(Verified Answers) Plus Rationale2026
Q&A| Instant Download Pdf
1. What is the primary purpose of a wastewater treatment plant?
A. To generate electricity
B. To remove contaminants from water
C. To increase water hardness
D. To store water
B. To remove contaminants from water
Rationale: The main purpose of a wastewater treatment plant is to remove
physical, chemical, and biological contaminants from water to make it safe
for discharge or reuse.
2. Which of the following is considered a primary treatment process?
A. Activated sludge
B. Sedimentation
C. Chlorination
D. Trickling filter
B. Sedimentation
Rationale: Primary treatment involves physical processes like
sedimentation to remove suspended solids.
3. Secondary treatment in wastewater primarily targets:
A. Dissolved solids
B. Pathogens
, C. Organic matter
D. Heavy metals
C. Organic matter
Rationale: Secondary treatment uses biological processes to break down
organic matter.
4. What is the typical purpose of a grit chamber?
A. Remove dissolved chemicals
B. Settle heavy inorganic solids
C. Kill bacteria
D. Aerate water
B. Settle heavy inorganic solids
Rationale: Grit chambers remove sand, gravel, and other heavy particles to
prevent damage to downstream equipment.
5. Which bacteria are primarily responsible for breaking down organic
waste in activated sludge systems?
A. Anaerobic bacteria
B. Nitrifying bacteria
C. Heterotrophic bacteria
D. Sulfate-reducing bacteria
C. Heterotrophic bacteria
Rationale: Heterotrophic bacteria consume organic carbon compounds in
wastewater.
6. What is the main advantage of an aeration tank?
A. Reduces sludge production
B. Increases oxygen supply to microorganisms
C. Removes heavy metals
D. Reduces water temperature
B. Increases oxygen supply to microorganisms
Rationale: Aeration tanks provide oxygen needed for aerobic bacteria to
degrade organic matter.
, 7. Which process is used to remove nitrogen from wastewater?
A. Chlorination
B. Nitrification and denitrification
C. Flocculation
D. Sedimentation
B. Nitrification and denitrification
Rationale: Nitrogen is removed biologically through nitrification (ammonia
to nitrate) and denitrification (nitrate to nitrogen gas).
8. Which chemical is commonly used for disinfection in wastewater
treatment?
A. Sodium hydroxide
B. Chlorine
C. Ferric chloride
D. Calcium carbonate
B. Chlorine
Rationale: Chlorine is widely used for disinfection due to its ability to kill
pathogens.
9. In wastewater treatment, BOD stands for:
A. Biological Oxidation Demand
B. Biochemical Oxygen Demand
C. Basic Oxygen Density
D. Biochemical Organic Decomposition
B. Biochemical Oxygen Demand
Rationale: BOD measures the amount of dissolved oxygen needed by
microorganisms to decompose organic matter.
10. What is the function of a clarifier in wastewater treatment?
A. Aerate water
B. Remove solids by settling
C. Add nutrients
D. Neutralize pH
