Wastewater Treatment Operator
Certification Test #2. Latest 2026-2027.
Questions & Correct Verified Answers.
Graded A
During the day, what typically happens to a pond as a result of the algae?
A) Algae uses carbon dioxide, which raises pH
B) Algae produces carbon dioxide, which lowers pH
C) Algae consumes carbon dioxide, which lower pH
D) Algae releases carbon dioxide, which raises pH - ANSA) Algae uses
carbon dioxide, which raises pH (v.1 pg 299)
How can the efficiency of a trickling filter be improved?
A) Raise the distributor arm
B) Reduce the size of the ventilation ports
C) Decrease the amount of the filter media
D) Add recirculation - ANSD) Add recirculation (v.1 pg 175)
How often should grit be removed from the grit channel?
A) Weekly
B) Monthly
C) Bi-weekly
1
,D) Daily - ANSD) Daily (v.1 pg 87)
If you are testing the pH of a wastewater sample, what is the maximum
recommended holding time?
A) 5 days
B) It must be tested immediately
C) 24 hours
D) 36 hours - ANSB) It must be tested immediately (v.2 pg 502)
One to two percent of the digester gas in an anaerobic consists of
A) Hydrogen, Nitrogen, Hydrogen sulfide, and other gases
B) Methane
C) Carbon Dioxide
D) CH_4 - ANSA) Hydrogen, Nitrogen, Hydrogen sulfide, and other gases
(v.2 pg 158)
What are colloids?
A) Solids that settle rapidly
B) Dissolved solids
C) Solids found in the grit channel
D) Very small, finely divided solids that remain dispersed in a liquid for a
long time - ANSD) Very small, finely divided solids that remain dispersed in
a liquid for a long time (v.1 pg 22,144)
2
, What are commonly used to control chlorine feed rate for disinfection?
A) BOD and MLVSS
B) pH and temperature
C) Flow and chlorine residual
D) DO and TSS - ANSC) Flow and chlorine residual (v.1 pg 356)
What are screenings?
A) Colloids
B) TDS
C) Pieces of wood, roots, rags, and other large debris
D) COD - ANSC) Pieces of wood, roots, rags, and other large debris (v.1
pg 41)
What causes primary effluent to become black and odorous?
A) Excessive sludge pumping
B) Oil leak from the sludge pump
C) Crack in the launder
D) Improper sludge removal from the clarifier - ANSD) Improper sludge
removal from the clarifier (v.1 pg 123)
What could cause a sudden drop in pH of the influent?
A) Acidic chemical in the influent
B) A strong base was dumped into the collection system
3
Certification Test #2. Latest 2026-2027.
Questions & Correct Verified Answers.
Graded A
During the day, what typically happens to a pond as a result of the algae?
A) Algae uses carbon dioxide, which raises pH
B) Algae produces carbon dioxide, which lowers pH
C) Algae consumes carbon dioxide, which lower pH
D) Algae releases carbon dioxide, which raises pH - ANSA) Algae uses
carbon dioxide, which raises pH (v.1 pg 299)
How can the efficiency of a trickling filter be improved?
A) Raise the distributor arm
B) Reduce the size of the ventilation ports
C) Decrease the amount of the filter media
D) Add recirculation - ANSD) Add recirculation (v.1 pg 175)
How often should grit be removed from the grit channel?
A) Weekly
B) Monthly
C) Bi-weekly
1
,D) Daily - ANSD) Daily (v.1 pg 87)
If you are testing the pH of a wastewater sample, what is the maximum
recommended holding time?
A) 5 days
B) It must be tested immediately
C) 24 hours
D) 36 hours - ANSB) It must be tested immediately (v.2 pg 502)
One to two percent of the digester gas in an anaerobic consists of
A) Hydrogen, Nitrogen, Hydrogen sulfide, and other gases
B) Methane
C) Carbon Dioxide
D) CH_4 - ANSA) Hydrogen, Nitrogen, Hydrogen sulfide, and other gases
(v.2 pg 158)
What are colloids?
A) Solids that settle rapidly
B) Dissolved solids
C) Solids found in the grit channel
D) Very small, finely divided solids that remain dispersed in a liquid for a
long time - ANSD) Very small, finely divided solids that remain dispersed in
a liquid for a long time (v.1 pg 22,144)
2
, What are commonly used to control chlorine feed rate for disinfection?
A) BOD and MLVSS
B) pH and temperature
C) Flow and chlorine residual
D) DO and TSS - ANSC) Flow and chlorine residual (v.1 pg 356)
What are screenings?
A) Colloids
B) TDS
C) Pieces of wood, roots, rags, and other large debris
D) COD - ANSC) Pieces of wood, roots, rags, and other large debris (v.1
pg 41)
What causes primary effluent to become black and odorous?
A) Excessive sludge pumping
B) Oil leak from the sludge pump
C) Crack in the launder
D) Improper sludge removal from the clarifier - ANSD) Improper sludge
removal from the clarifier (v.1 pg 123)
What could cause a sudden drop in pH of the influent?
A) Acidic chemical in the influent
B) A strong base was dumped into the collection system
3
