Page 1 of 91
Wastewater Treatment Operator Certification TEST
2 ALL 280 QUESTIONS AND CORRECT ANSWERS
LATEST UPDATE THIS YEAR
Wastewater Treatment Operator Certification TEST 2
QUESTION: What type of sludge would you expect in an aeration tank if the content is dark and
has low DO?
A) Sludge that is heavy
B) Chlorinated Sludge
C) Septic Sludge
D) Healthy Sludge - ANSWER-C) Septic Sludge (v.2 pg 75)
QUESTION: What could have happen if the volatile acid/alkalinity ratio starts to increase, and
corrective action is not taken immediately?
A) Carbon dioxide content in the digester gas will decrease
B) Carbon monoxide content in the digester gas will fluctuate
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C) pH of the digester sludge will increase
D) Carbon dioxide content in the digester gas will increase - ANSWER-D) Carbon dioxide content
in the digester gas will increase (v.2 pg 191)
QUESTION: What are screenings?
A) Colloids
B) TDS
C) Pieces of wood, roots, rags, and other large debris
D) COD - ANSWER-C) Pieces of wood, roots, rags, and other large debris (v.1 pg 41)
QUESTION: What happens when there is more food in the influent to the aeration tank?
A) Less oxygen is required in the aeration tank
B) More oxygen is required in the aeration tank
C) Less organism activity takes place
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D) Less oxidation takes place - ANSWER-B) More oxygen is required in the aeration tank (v.2 pg
19)
QUESTION: What impact does temperature have on the reaction rate of microorganisms in
wastewater?
A) Reaction rate doubles with every 18 degree Fahrenheit increase in temperature until higher
temperature inhibits biological activity
B) Reaction rate decreases by 20% with every 10 degree Fahrenheit increase in temperature
C) Reaction rate of microorganism is not impacted by temperature
D) Reaction rate goes to zero - ANSWER-A) Reaction rate doubles with every 18 degree
Fahrenheit increase in temperature until higher
QUESTION: What is commonly used to control the odor of hydrogen sulfide?
A) Carbon Dioxide
B) Methane
C) Chlorine
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D) Hydrogen - ANSWER-C) Chlorine (v.1 pg 398)
QUESTION: What is used to determine the amount of microorganisms in the aeration tank?
A) Mixed Liquor Suspended Solids (MLSS)
B) Influent TSS
C) BOD
D) Mixed Liquor Volatile Suspended Solids (MLVSS) - ANSWER-D) Mixed Liquor Volatile
Suspended Solids (MLVSS) (v.2 pg 58)
Q; What is the typical BOD removal efficiency in a primary clarifier?
A) 10 to 15%
B) 40 to 60%
C) 20 to 50%
D) 95 to 99% - ANSWER-C) 20 to 50% (v.1 pg 129)
QUESTION: What does the "F" in F/M ratio represent?
4
Wastewater Treatment Operator Certification TEST
2 ALL 280 QUESTIONS AND CORRECT ANSWERS
LATEST UPDATE THIS YEAR
Wastewater Treatment Operator Certification TEST 2
QUESTION: What type of sludge would you expect in an aeration tank if the content is dark and
has low DO?
A) Sludge that is heavy
B) Chlorinated Sludge
C) Septic Sludge
D) Healthy Sludge - ANSWER-C) Septic Sludge (v.2 pg 75)
QUESTION: What could have happen if the volatile acid/alkalinity ratio starts to increase, and
corrective action is not taken immediately?
A) Carbon dioxide content in the digester gas will decrease
B) Carbon monoxide content in the digester gas will fluctuate
1
, Page 2 of 91
C) pH of the digester sludge will increase
D) Carbon dioxide content in the digester gas will increase - ANSWER-D) Carbon dioxide content
in the digester gas will increase (v.2 pg 191)
QUESTION: What are screenings?
A) Colloids
B) TDS
C) Pieces of wood, roots, rags, and other large debris
D) COD - ANSWER-C) Pieces of wood, roots, rags, and other large debris (v.1 pg 41)
QUESTION: What happens when there is more food in the influent to the aeration tank?
A) Less oxygen is required in the aeration tank
B) More oxygen is required in the aeration tank
C) Less organism activity takes place
2
, Page 3 of 91
D) Less oxidation takes place - ANSWER-B) More oxygen is required in the aeration tank (v.2 pg
19)
QUESTION: What impact does temperature have on the reaction rate of microorganisms in
wastewater?
A) Reaction rate doubles with every 18 degree Fahrenheit increase in temperature until higher
temperature inhibits biological activity
B) Reaction rate decreases by 20% with every 10 degree Fahrenheit increase in temperature
C) Reaction rate of microorganism is not impacted by temperature
D) Reaction rate goes to zero - ANSWER-A) Reaction rate doubles with every 18 degree
Fahrenheit increase in temperature until higher
QUESTION: What is commonly used to control the odor of hydrogen sulfide?
A) Carbon Dioxide
B) Methane
C) Chlorine
3
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D) Hydrogen - ANSWER-C) Chlorine (v.1 pg 398)
QUESTION: What is used to determine the amount of microorganisms in the aeration tank?
A) Mixed Liquor Suspended Solids (MLSS)
B) Influent TSS
C) BOD
D) Mixed Liquor Volatile Suspended Solids (MLVSS) - ANSWER-D) Mixed Liquor Volatile
Suspended Solids (MLVSS) (v.2 pg 58)
Q; What is the typical BOD removal efficiency in a primary clarifier?
A) 10 to 15%
B) 40 to 60%
C) 20 to 50%
D) 95 to 99% - ANSWER-C) 20 to 50% (v.1 pg 129)
QUESTION: What does the "F" in F/M ratio represent?
4
