Wastewater Treatment Operator
Certification Test 1 with questions and
correct answers
What is the methane content in a properly operation anaerobic digester?
A) 30 to 35% by volume
B) 1 to 2% by volume
C) 65 to 70% by volume
D) 15 to 20% by volume - ANSWER-C) 65 to 70% by volume (v.2 pg 158)
What will the addition of chlorine gas do to the pH of wastewater?
A) Moderately increase pH
B) pH will not be affected
C) Significantly increase the pH
D) Decrease the pH - ANSWER-D) Decrease the pH (v.1 pg 349-350)
What is the purpose of a Parshall flume?
A) measure turbidity
B) measure flowrate
C) measure settling rate
D) measure solids content - ANSWER-B) measure flowrate (v.1 pg 43)
What is the typical removal efficiency of settable solids in a primary
clarifier?
A) 95 to 99%
B) 40 to 60%
C) 20 to 50%
D) 10 to 15% - ANSWER-A) 95 to 99% (v.1 pg 129)
Which of the following is true about pumping scum from a primary clarifier?
A) Pumping scum is less problematic during colder weather.
B) Scum rarely leads to plugged pipelines due to its viscous nature.
,C) Scum causes more piping problems than other substances pumped at a
wastewater treatment plant.
D) Scum causes the least amount of piping problems among all the
substances pumped at a wastewater treatment plant. - ANSWER-C) Scum
causes more piping problems than other substances pumped at a
wastewater treatment plant. (v.2 pg 449)
What might cause thick billows of white sudsy foam in the aeration tank?
A) MLSS is too high
B) Temperature in the aeration tank is too low
C) Old sludge
D) MLSS is too low - ANSWER-D) MLSS is too low (v.2 pg 53,75)
What does the "M" in F/M ratio represent?
A) MLSS in aeration tank
B) The influent BOD loading rate into the aeration tank
C) The mixed liquor volatile suspended solids in the aeration tank
D) The mass of inorganic solids in the aeration tank - ANSWER-C) The
mixed liquor volatile suspended solids in the aeration tank (v.2 pg 16)
In general, how will warmer temperature affect the settling rate of solids in
a clarifier?
A) Decrease settling rate
B) Increase the settling rate
C) Temperature will not affect the settling rate
D) Worsen the settling rate - ANSWER-B) Increase the settling rate (v.1 pg
134)
What could happen if the digester gas is mixed with air (85 to 95% by
volume)?
A) Cause an explosion
B) Improve efficiency of digestion
C) The bacteria will become aerobic and increase VSR
D) The digester becomes safer to operate due to less toxic gas in the
system - ANSWER-A) Cause an explosion (v.2 pg 158)
,How will algae impact the chlorine demand in the pond effluent?
A) Slightly decreases chlorine demand
B) Does not affect chlorine demand
C) Significantly decreases chlorine demand
D) Increases chlorine demand - ANSWER-D) Increases chlorine demand
Which of the following is true about positive displacement pumps?
A) It is a type of centrifugal pump
B) Suction valve should be closed when the pump is started
C) It must never be started with the discharge valve closed
D) Adds head to liquid using several impellers - ANSWER-C) It must never
be started with the discharge valve closed (v.2 pg 435)
What is true about the F/M ratio?
A) MLVSS data in not required to determine the F/M ration
B) Volume of the secondary clarifier is not needed to determine the F/M
ratio
C) The amount of COD or BOD entering the aeration tank does not have to
be known to calculate the F/M ratio.
D) The amount of organisms in the aeration tank is not needed to calculate
the F/M ratio - ANSWER-B) Volume of the secondary clarifier is not needed
to determine the F/M ratio (v.2 pg 58)
Which of the following is one of the basic rules of laboratory work?
A) Do not leave keys in equipment or vehicles at any time
B) Patrol the facilities frequently, and look for suspicious activity or behavior
C) never pipet hazardous material with your mouth, even if the pipet has be
sterilized
D) Lock out and tag out relevant mechanical and electrical equipment
before starting any maintenance activity. - ANSWER-C) never pipet
hazardous material with your mouth, even if the pipet has be sterilized (v.2
pg 493)
What is the recirculation ratio for a trickling filter?
A) Q_r/Q
, B) Q/Q_r
C) Q/Q_r+Q
D) Q_r+Q/Q - ANSWER-A) Q_r/Q
Which of the following is true about COD and BOD?
A) They are direct measurements of organic content in the influent
B) They measure the inorganic content of the influent
C) They represent the amount of filamentous bacteria in the influent
D) They are indirect measurements of the organic content in the influent -
ANSWER-D) They are indirect measurements of the organic content in the
influent
What is the purpose of the grit channel?
A) Remove dissolved and non-settleable organics
B) Remove heavy inorganic wastes
C) To allow activated sludge to settle
D) Remove substances that float and readily settle from the wastewater as
part of primary treatment - ANSWER-B) Remove heavy inorganic wastes
(v.1 pg 84)
Which of the following is true about the extended aeration process?
A) Bugs get more food
B) Wasting is not necessary
C) It does not produce as much waste sludge as the other processes
D) It is very different from the conventional activated sludge process -
ANSWER-C) It does not produce as much waste sludge as the other
processes (v.1 pg 257)
What is the correct formula for solids in raw wastewater?
A) Non-volatile solids + Suspended solids= Total solids in the influent
B) Dissolved solids + Settable solids= Total suspended solids
C) Colloids + Dissolved solids = Total suspended solids
D) Non-settleable solids + Settable solids= Total suspended solids. -
ANSWER-D) Non-settleable solids + Settable solids= Total suspended
solids (v.1 pg 22)
Certification Test 1 with questions and
correct answers
What is the methane content in a properly operation anaerobic digester?
A) 30 to 35% by volume
B) 1 to 2% by volume
C) 65 to 70% by volume
D) 15 to 20% by volume - ANSWER-C) 65 to 70% by volume (v.2 pg 158)
What will the addition of chlorine gas do to the pH of wastewater?
A) Moderately increase pH
B) pH will not be affected
C) Significantly increase the pH
D) Decrease the pH - ANSWER-D) Decrease the pH (v.1 pg 349-350)
What is the purpose of a Parshall flume?
A) measure turbidity
B) measure flowrate
C) measure settling rate
D) measure solids content - ANSWER-B) measure flowrate (v.1 pg 43)
What is the typical removal efficiency of settable solids in a primary
clarifier?
A) 95 to 99%
B) 40 to 60%
C) 20 to 50%
D) 10 to 15% - ANSWER-A) 95 to 99% (v.1 pg 129)
Which of the following is true about pumping scum from a primary clarifier?
A) Pumping scum is less problematic during colder weather.
B) Scum rarely leads to plugged pipelines due to its viscous nature.
,C) Scum causes more piping problems than other substances pumped at a
wastewater treatment plant.
D) Scum causes the least amount of piping problems among all the
substances pumped at a wastewater treatment plant. - ANSWER-C) Scum
causes more piping problems than other substances pumped at a
wastewater treatment plant. (v.2 pg 449)
What might cause thick billows of white sudsy foam in the aeration tank?
A) MLSS is too high
B) Temperature in the aeration tank is too low
C) Old sludge
D) MLSS is too low - ANSWER-D) MLSS is too low (v.2 pg 53,75)
What does the "M" in F/M ratio represent?
A) MLSS in aeration tank
B) The influent BOD loading rate into the aeration tank
C) The mixed liquor volatile suspended solids in the aeration tank
D) The mass of inorganic solids in the aeration tank - ANSWER-C) The
mixed liquor volatile suspended solids in the aeration tank (v.2 pg 16)
In general, how will warmer temperature affect the settling rate of solids in
a clarifier?
A) Decrease settling rate
B) Increase the settling rate
C) Temperature will not affect the settling rate
D) Worsen the settling rate - ANSWER-B) Increase the settling rate (v.1 pg
134)
What could happen if the digester gas is mixed with air (85 to 95% by
volume)?
A) Cause an explosion
B) Improve efficiency of digestion
C) The bacteria will become aerobic and increase VSR
D) The digester becomes safer to operate due to less toxic gas in the
system - ANSWER-A) Cause an explosion (v.2 pg 158)
,How will algae impact the chlorine demand in the pond effluent?
A) Slightly decreases chlorine demand
B) Does not affect chlorine demand
C) Significantly decreases chlorine demand
D) Increases chlorine demand - ANSWER-D) Increases chlorine demand
Which of the following is true about positive displacement pumps?
A) It is a type of centrifugal pump
B) Suction valve should be closed when the pump is started
C) It must never be started with the discharge valve closed
D) Adds head to liquid using several impellers - ANSWER-C) It must never
be started with the discharge valve closed (v.2 pg 435)
What is true about the F/M ratio?
A) MLVSS data in not required to determine the F/M ration
B) Volume of the secondary clarifier is not needed to determine the F/M
ratio
C) The amount of COD or BOD entering the aeration tank does not have to
be known to calculate the F/M ratio.
D) The amount of organisms in the aeration tank is not needed to calculate
the F/M ratio - ANSWER-B) Volume of the secondary clarifier is not needed
to determine the F/M ratio (v.2 pg 58)
Which of the following is one of the basic rules of laboratory work?
A) Do not leave keys in equipment or vehicles at any time
B) Patrol the facilities frequently, and look for suspicious activity or behavior
C) never pipet hazardous material with your mouth, even if the pipet has be
sterilized
D) Lock out and tag out relevant mechanical and electrical equipment
before starting any maintenance activity. - ANSWER-C) never pipet
hazardous material with your mouth, even if the pipet has be sterilized (v.2
pg 493)
What is the recirculation ratio for a trickling filter?
A) Q_r/Q
, B) Q/Q_r
C) Q/Q_r+Q
D) Q_r+Q/Q - ANSWER-A) Q_r/Q
Which of the following is true about COD and BOD?
A) They are direct measurements of organic content in the influent
B) They measure the inorganic content of the influent
C) They represent the amount of filamentous bacteria in the influent
D) They are indirect measurements of the organic content in the influent -
ANSWER-D) They are indirect measurements of the organic content in the
influent
What is the purpose of the grit channel?
A) Remove dissolved and non-settleable organics
B) Remove heavy inorganic wastes
C) To allow activated sludge to settle
D) Remove substances that float and readily settle from the wastewater as
part of primary treatment - ANSWER-B) Remove heavy inorganic wastes
(v.1 pg 84)
Which of the following is true about the extended aeration process?
A) Bugs get more food
B) Wasting is not necessary
C) It does not produce as much waste sludge as the other processes
D) It is very different from the conventional activated sludge process -
ANSWER-C) It does not produce as much waste sludge as the other
processes (v.1 pg 257)
What is the correct formula for solids in raw wastewater?
A) Non-volatile solids + Suspended solids= Total solids in the influent
B) Dissolved solids + Settable solids= Total suspended solids
C) Colloids + Dissolved solids = Total suspended solids
D) Non-settleable solids + Settable solids= Total suspended solids. -
ANSWER-D) Non-settleable solids + Settable solids= Total suspended
solids (v.1 pg 22)
