Page 1 of 54
Wastewater Treatment Operator Certification
EXAM 3&4 ALL 200 QUESTIONS AND CORRECT
ANSWERS LATEST UPDATE THIS YEAR
Wastewater Treatment Operator Certification EXAM 3
QUESTION: Which of the following is true about bacteria?
A) The Most Probable Number method is not applicable for analyzing wastewater for coliform,
but it is frequently used to determine the ciliate concentration
B) Multiple tube coliform test is not frequently used to determine coliform bacteria due to its
complexity
C) Coliform bacteria are considered harmless, but their presence may indicate the presence of
pathogens.
D) Test for coliform bacteria cannot be used by an operator at a treatment plant as a guide to
achieve desired degree of treatment. - ANSWER-C) Coliform bacteria are considered harmless,
but their presence may indicate the presence of pathogens (v.2 pg 551,553)
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, Page 2 of 54
QUESTION: What is the typical removal efficiency of total suspended solids in the primary
clarifier?
A) 95 to 99%
B) 20 to 50%
C) 10 to 15%
D) 40 to 60% - ANSWER-D) 40 to 60% (v.1 pg 129)
QUESTION: Which of the following is the most abundant in an anaerobic digester?
A) Carbon dioxide
B) Nitrogen
C) Methane
D) Hydrogen sulfide - ANSWER-C) Methane (v.2 pg 158)
QUESTION: What might cause brown or black scum to appear on the surface of a pond?
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A) Low BOD loading
B) Pond is overloading (BOD)
C) Storm
D) Periods of high runoff - ANSWER-B) Pond is overloading (BOD) (v.1 pg 308)
QUESTION: What is the purpose of air input for an aerated grit chamber?
A) Helps remove TDS
B) Air improves the disinfection process
C) Freshens wastewater and helps separate grit and other solids
D) Addresses denitrification - ANSWER-C) Freshens wastewater and helps separate grit and
other solids (v.1 pg 42)
QUESTION: What happens when there are many air bubbles in the water of an operating
pump?
A) Water hammer
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, Page 4 of 54
B) Cavitation
C) Less noise generated by the pump
D) More efficient pumping - ANSWER-B) Cavitation (v.2 pg 346)
QUESTION: Which are the common characteristics of COD?
A) COD is typically larger than BOD and COD test results are available sooner than BOD
B) COD is typically smaller than BOD
C) COD is usually equal to BOD
D) COD results are available after 4 days of testing - ANSWER-A) COD is typically larger than
BOD and COD test results are available sooner than BOD (v.2 pg 541)
QUESTION: What happens when free chlorine reacts with ammonia?
A) Forms chlorine dioxide
B) Forms hydrogen sulfide
C) Forms ozone
4
Wastewater Treatment Operator Certification
EXAM 3&4 ALL 200 QUESTIONS AND CORRECT
ANSWERS LATEST UPDATE THIS YEAR
Wastewater Treatment Operator Certification EXAM 3
QUESTION: Which of the following is true about bacteria?
A) The Most Probable Number method is not applicable for analyzing wastewater for coliform,
but it is frequently used to determine the ciliate concentration
B) Multiple tube coliform test is not frequently used to determine coliform bacteria due to its
complexity
C) Coliform bacteria are considered harmless, but their presence may indicate the presence of
pathogens.
D) Test for coliform bacteria cannot be used by an operator at a treatment plant as a guide to
achieve desired degree of treatment. - ANSWER-C) Coliform bacteria are considered harmless,
but their presence may indicate the presence of pathogens (v.2 pg 551,553)
1
, Page 2 of 54
QUESTION: What is the typical removal efficiency of total suspended solids in the primary
clarifier?
A) 95 to 99%
B) 20 to 50%
C) 10 to 15%
D) 40 to 60% - ANSWER-D) 40 to 60% (v.1 pg 129)
QUESTION: Which of the following is the most abundant in an anaerobic digester?
A) Carbon dioxide
B) Nitrogen
C) Methane
D) Hydrogen sulfide - ANSWER-C) Methane (v.2 pg 158)
QUESTION: What might cause brown or black scum to appear on the surface of a pond?
2
, Page 3 of 54
A) Low BOD loading
B) Pond is overloading (BOD)
C) Storm
D) Periods of high runoff - ANSWER-B) Pond is overloading (BOD) (v.1 pg 308)
QUESTION: What is the purpose of air input for an aerated grit chamber?
A) Helps remove TDS
B) Air improves the disinfection process
C) Freshens wastewater and helps separate grit and other solids
D) Addresses denitrification - ANSWER-C) Freshens wastewater and helps separate grit and
other solids (v.1 pg 42)
QUESTION: What happens when there are many air bubbles in the water of an operating
pump?
A) Water hammer
3
, Page 4 of 54
B) Cavitation
C) Less noise generated by the pump
D) More efficient pumping - ANSWER-B) Cavitation (v.2 pg 346)
QUESTION: Which are the common characteristics of COD?
A) COD is typically larger than BOD and COD test results are available sooner than BOD
B) COD is typically smaller than BOD
C) COD is usually equal to BOD
D) COD results are available after 4 days of testing - ANSWER-A) COD is typically larger than
BOD and COD test results are available sooner than BOD (v.2 pg 541)
QUESTION: What happens when free chlorine reacts with ammonia?
A) Forms chlorine dioxide
B) Forms hydrogen sulfide
C) Forms ozone
4
