Wastewater Treatment Operator Certification Test #2 |
Actual Exam Questions & 100% Correct Answers | Latest
Update 2026 | Certification Exam Prep
1. Describe why maintaining a balance between acid formation and methane
formation is crucial in anaerobic digestion.
Maintaining a balance is not important as both processes occur
independently.
Maintaining a balance is crucial because excessive acid formation
can inhibit methane production, leading to inefficient digestion.
Maintaining a balance ensures that the digester operates at maximum
temperature.
Maintaining a balance only affects the loading rate of the digester.
2. Describe how an acidic chemical in the influent can affect the overall
wastewater treatment process.
An acidic chemical can lower the pH of the influent, potentially
harming microorganisms essential for treatment.
An acidic chemical will enhance the growth of microorganisms in the
treatment system.
An acidic chemical will increase the BOD levels in the influent, making
treatment easier.
An acidic chemical has no effect on the treatment process as it is
neutralized by chlorine.
3. What type of materials are typically removed during the screening process in
wastewater treatment?
, Chemical pollutants
Pieces of wood, roots, rags, and other large debris
Dissolved solids
Microorganisms
4. What type of disinfection is gaining popularity, and expected to become a
practical alternative to chlorination?
Aqueous ammonia
Caustic soda
Sulfur dioxide
Ultraviolet (UV) disinfection
5. If a wastewater treatment facility operates with chlorine gas levels
consistently above the permissible exposure limit, what immediate action
should be taken to protect workers?
Increase the dosage of chlorine to improve treatment efficiency.
Conduct a study on the effects of chlorine on wastewater treatment.
Ignore the levels as long as treatment goals are met.
Implement safety measures to reduce chlorine exposure.
6. If a wastewater treatment plant is experiencing high levels of BOD and solids,
what operational changes might be necessary to restore optimal
performance?
Increase aeration and reduce inflow rates.
Reduce the number of microorganisms in the system.
Add more chlorine to the treatment process.
Decrease aeration and increase inflow rates.
,7. In the activated sludge process, the term F/M ratio is important because this
refers to-
Food to Macro-organisms Ratio
Food to Microorganisms Ratio
Female micros to Male micros Ratio
Frequent to Minimal Ratio
Front loading to Middle processing ratio
8. The gas most typically associated with septic wastewater is?
carbon dioxide
hydrogen sulfide
carbon monoxide
merhane
9. Which statement best describes Chain of Custody?
samples should be sent by standard USPS mailing procedures
samples must be traceable from collection to analysis
samples should be redundantly labeled according to CFR Part 172
samples must be verified prior to analysis
10. In a scenario where a wastewater treatment plant is experiencing poor
settling in the secondary clarifier, what operational change could be made
to address low dissolved oxygen levels in the aeration tank?
Decrease the temperature of the aeration tank.
Add chemicals to enhance floc formation.
, Increase aeration to boost dissolved oxygen levels.
Reduce the inflow of wastewater to the aeration tank.
11. Chlorine gas is:
none of the above
colorless and 2.5 times lighter than air
greenish-yellow and 2.5 times heavier than air
greenish-yellow and the same density as air
12. Describe the settling characteristics of activated sludge compared to raw
sludge and explain why this difference is significant in wastewater treatment.
Activated sludge settles faster than raw sludge, which is significant
for reducing treatment time.
Activated sludge settles slower than raw sludge, which is significant
because it affects the efficiency of the treatment process.
Activated sludge does not settle, which is crucial for maintaining
water quality.
Activated sludge settles at the same rate as raw sludge, which is
important for uniform treatment.
13. What is the definition of sludge bulking in the context of wastewater
treatment?
When sludge forms large aggregates and causes sludge to settle
quickly
When compaction in the secondary clarifier is improved due to
chemical injection
When mixed liquor solids settle slowly and compact to a limited
extent
Actual Exam Questions & 100% Correct Answers | Latest
Update 2026 | Certification Exam Prep
1. Describe why maintaining a balance between acid formation and methane
formation is crucial in anaerobic digestion.
Maintaining a balance is not important as both processes occur
independently.
Maintaining a balance is crucial because excessive acid formation
can inhibit methane production, leading to inefficient digestion.
Maintaining a balance ensures that the digester operates at maximum
temperature.
Maintaining a balance only affects the loading rate of the digester.
2. Describe how an acidic chemical in the influent can affect the overall
wastewater treatment process.
An acidic chemical can lower the pH of the influent, potentially
harming microorganisms essential for treatment.
An acidic chemical will enhance the growth of microorganisms in the
treatment system.
An acidic chemical will increase the BOD levels in the influent, making
treatment easier.
An acidic chemical has no effect on the treatment process as it is
neutralized by chlorine.
3. What type of materials are typically removed during the screening process in
wastewater treatment?
, Chemical pollutants
Pieces of wood, roots, rags, and other large debris
Dissolved solids
Microorganisms
4. What type of disinfection is gaining popularity, and expected to become a
practical alternative to chlorination?
Aqueous ammonia
Caustic soda
Sulfur dioxide
Ultraviolet (UV) disinfection
5. If a wastewater treatment facility operates with chlorine gas levels
consistently above the permissible exposure limit, what immediate action
should be taken to protect workers?
Increase the dosage of chlorine to improve treatment efficiency.
Conduct a study on the effects of chlorine on wastewater treatment.
Ignore the levels as long as treatment goals are met.
Implement safety measures to reduce chlorine exposure.
6. If a wastewater treatment plant is experiencing high levels of BOD and solids,
what operational changes might be necessary to restore optimal
performance?
Increase aeration and reduce inflow rates.
Reduce the number of microorganisms in the system.
Add more chlorine to the treatment process.
Decrease aeration and increase inflow rates.
,7. In the activated sludge process, the term F/M ratio is important because this
refers to-
Food to Macro-organisms Ratio
Food to Microorganisms Ratio
Female micros to Male micros Ratio
Frequent to Minimal Ratio
Front loading to Middle processing ratio
8. The gas most typically associated with septic wastewater is?
carbon dioxide
hydrogen sulfide
carbon monoxide
merhane
9. Which statement best describes Chain of Custody?
samples should be sent by standard USPS mailing procedures
samples must be traceable from collection to analysis
samples should be redundantly labeled according to CFR Part 172
samples must be verified prior to analysis
10. In a scenario where a wastewater treatment plant is experiencing poor
settling in the secondary clarifier, what operational change could be made
to address low dissolved oxygen levels in the aeration tank?
Decrease the temperature of the aeration tank.
Add chemicals to enhance floc formation.
, Increase aeration to boost dissolved oxygen levels.
Reduce the inflow of wastewater to the aeration tank.
11. Chlorine gas is:
none of the above
colorless and 2.5 times lighter than air
greenish-yellow and 2.5 times heavier than air
greenish-yellow and the same density as air
12. Describe the settling characteristics of activated sludge compared to raw
sludge and explain why this difference is significant in wastewater treatment.
Activated sludge settles faster than raw sludge, which is significant
for reducing treatment time.
Activated sludge settles slower than raw sludge, which is significant
because it affects the efficiency of the treatment process.
Activated sludge does not settle, which is crucial for maintaining
water quality.
Activated sludge settles at the same rate as raw sludge, which is
important for uniform treatment.
13. What is the definition of sludge bulking in the context of wastewater
treatment?
When sludge forms large aggregates and causes sludge to settle
quickly
When compaction in the secondary clarifier is improved due to
chemical injection
When mixed liquor solids settle slowly and compact to a limited
extent
