New Jersey Wastewater Treatment Operator
Exam S3 Questions And Correct Answers
(Verified Answers) Plus Rationales 2026 Q&A |
Instant Download Pdf
1. What is the primary purpose of a grit chamber in a wastewater
treatment plant?
a) Reduce organic load
b) Remove sand, gravel, and other heavy particles
c) Reduce pathogens
d) Aerate wastewater
Grit chambers remove heavy inorganic particles to prevent wear on
pumps and equipment and reduce sediment accumulation downstream.
2. The term BOD stands for:
a) Biological Oxidation Demand
b) Biochemical Oxygen Demand
c) Basic Oxidation Dose
d) Biological Oxygen Density
BOD measures the amount of oxygen required by microorganisms to
decompose organic matter in water over a specified period.
3. Which microorganism is primarily responsible for nitrification in
wastewater?
a) Escherichia coli
b) Nitrosomonas and Nitrobacter
, c) Streptococcus
d) Clostridium
Nitrifying bacteria like Nitrosomonas and Nitrobacter convert ammonia
to nitrite and nitrate in aerobic conditions.
4. What is the typical pH range for activated sludge processes?
a) 3.0–5.0
b) 5.5–6.0
c) 6.5–8.5
d) 9.0–10.5
Maintaining a pH of 6.5–8.5 ensures optimal microbial activity in
activated sludge systems.
5. The purpose of a primary clarifier is to:
a) Remove dissolved oxygen
b) Settle suspended solids
c) Remove nitrogen
d) Increase BOD
Primary clarifiers remove settleable solids and reduce the organic load
before secondary treatment.
6. Sludge age (or solids retention time) affects:
a) pH only
b) Microbial population and treatment efficiency
c) Grit removal
d) Temperature
Sludge age controls the growth rate of microorganisms and influences
nitrification and overall treatment efficiency.
, 7. Which type of filter is commonly used in tertiary wastewater
treatment?
a) Trickling filter
b) Sand filter
c) Activated sludge basin
d) Grit chamber
Sand filters provide fine filtration to remove residual suspended solids
before discharge or reuse.
8. The purpose of chlorination in wastewater treatment is to:
a) Remove BOD
b) Disinfect the effluent
c) Remove heavy metals
d) Reduce pH
Chlorination kills pathogenic microorganisms to make treated effluent
safe for discharge.
9. Which of the following is a common cause of sludge bulking?
a) High dissolved oxygen
b) Low pH
c) Excess filamentous bacteria
d) High temperature
Filamentous bacteria can prevent proper settling, causing bulking in the
secondary clarifier.
10. The removal of nitrogen in wastewater primarily involves:
a) Coagulation
b) Sedimentation
Exam S3 Questions And Correct Answers
(Verified Answers) Plus Rationales 2026 Q&A |
Instant Download Pdf
1. What is the primary purpose of a grit chamber in a wastewater
treatment plant?
a) Reduce organic load
b) Remove sand, gravel, and other heavy particles
c) Reduce pathogens
d) Aerate wastewater
Grit chambers remove heavy inorganic particles to prevent wear on
pumps and equipment and reduce sediment accumulation downstream.
2. The term BOD stands for:
a) Biological Oxidation Demand
b) Biochemical Oxygen Demand
c) Basic Oxidation Dose
d) Biological Oxygen Density
BOD measures the amount of oxygen required by microorganisms to
decompose organic matter in water over a specified period.
3. Which microorganism is primarily responsible for nitrification in
wastewater?
a) Escherichia coli
b) Nitrosomonas and Nitrobacter
, c) Streptococcus
d) Clostridium
Nitrifying bacteria like Nitrosomonas and Nitrobacter convert ammonia
to nitrite and nitrate in aerobic conditions.
4. What is the typical pH range for activated sludge processes?
a) 3.0–5.0
b) 5.5–6.0
c) 6.5–8.5
d) 9.0–10.5
Maintaining a pH of 6.5–8.5 ensures optimal microbial activity in
activated sludge systems.
5. The purpose of a primary clarifier is to:
a) Remove dissolved oxygen
b) Settle suspended solids
c) Remove nitrogen
d) Increase BOD
Primary clarifiers remove settleable solids and reduce the organic load
before secondary treatment.
6. Sludge age (or solids retention time) affects:
a) pH only
b) Microbial population and treatment efficiency
c) Grit removal
d) Temperature
Sludge age controls the growth rate of microorganisms and influences
nitrification and overall treatment efficiency.
, 7. Which type of filter is commonly used in tertiary wastewater
treatment?
a) Trickling filter
b) Sand filter
c) Activated sludge basin
d) Grit chamber
Sand filters provide fine filtration to remove residual suspended solids
before discharge or reuse.
8. The purpose of chlorination in wastewater treatment is to:
a) Remove BOD
b) Disinfect the effluent
c) Remove heavy metals
d) Reduce pH
Chlorination kills pathogenic microorganisms to make treated effluent
safe for discharge.
9. Which of the following is a common cause of sludge bulking?
a) High dissolved oxygen
b) Low pH
c) Excess filamentous bacteria
d) High temperature
Filamentous bacteria can prevent proper settling, causing bulking in the
secondary clarifier.
10. The removal of nitrogen in wastewater primarily involves:
a) Coagulation
b) Sedimentation
