Wastewater Treatment Operator Certification
Test 2 final study guide 2024/2025
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%
C) 20 to 50% (v.1 pg 129)
What does the "F" in F/M ratio represent?
A) The microorganism population in the aeration tank
B) The amount of filamentous bacteria in the activated sludge process
C) The MLVSS in the aeration tank
D) The food for the microorganisms flowing into the aeration tank, in lbs/day
D) The food for the microorganisms flowing into the aeration tank, in lbs/day (v.2 pg 58)
Which of the following describes the appearance of healthy activated sludge?
A) Thick, greasy, dark tan foam
B) Brown with a moderate amount of crisp, white foam
C) Clear liquid with clear foam
D) Gray liquid with no foam
B) Brown with a moderate amount of crisp, white foam
What is used to control filamentous organisms?
A) Polymer
B) Sulfur Dioxide
C) Coagulant
D) Chlorine
D) Chlorine (v.1 pg 399)
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
C) Flow and chlorine residual (v.1 pg 356)
Which toxic gas is commonly found in septic wastewater and smells like rotten eggs?
A) Hydrogen Sulfide
B) Carbon monoxide
C) Hydrogen
D) Carbon Dioxide
A) Hydrogen Sulfide (v.2 pg 299)
, What is the permissible exposure limit for chlorine gas vapor during a normal 8 hour workday and a
40 hour work week?
A) 0.1 ppm
B) 0.5 ppm
C) 1 ppm
D) 15 ppm
B) 0.5 ppm (v.2 pg 268)
What is a vulnerability assessment?
A) Assesses the impact of hydrogen sulfide to a concrete structure
B) Analyzes the impact of flow and infiltration problem to the plant hydraulics
C) Estimates the vulnerability of aquatic wildlife to excessive algae growth
D) Contingency planning to determine the vulnerability of the utility during various types of
emergencies and identify corrective actions to reduce the risks
D) Contingency planning to determine the vulnerability of the utility during various types of
emergencies and identify corrective actions to reduce the risks (v.2 pg 722)
What is the difference between the settling rate of activated sludge and raw sludge?
A) Activated sludge settles slightly faster than raw sludge
B) Activated sludge settles at the same rate as raw sludge
C) Activated sludge settles slower than raw sludge
D) Activated sludge settles much faster than raw sludge
C) Activated sludge settles slower than raw sludge (v.1 pg 109)
What should be mostly found in healthy activated sludge?
A) Tiny flagellates
B) Amoeboids
C) Short Filaments
D) Free swimmers and stalked ciliates
D) Free swimmers and stalked ciliates (v.2 pg 120,124)
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
A) Hydrogen, Nitrogen, Hydrogen sulfide, and other gases (v.2 pg 158)
What is true during the colder winter months?
A) Modify operations to decrease solids under aeration to provide less microorganisms to treat the
BOD
B) Modify operations to increase solids under aeration to provide more microorganisms to treat the
BOD
C) Biological activity will increase, which results in more overall sludge production
D) Microorganisms become more active
Test 2 final study guide 2024/2025
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%
C) 20 to 50% (v.1 pg 129)
What does the "F" in F/M ratio represent?
A) The microorganism population in the aeration tank
B) The amount of filamentous bacteria in the activated sludge process
C) The MLVSS in the aeration tank
D) The food for the microorganisms flowing into the aeration tank, in lbs/day
D) The food for the microorganisms flowing into the aeration tank, in lbs/day (v.2 pg 58)
Which of the following describes the appearance of healthy activated sludge?
A) Thick, greasy, dark tan foam
B) Brown with a moderate amount of crisp, white foam
C) Clear liquid with clear foam
D) Gray liquid with no foam
B) Brown with a moderate amount of crisp, white foam
What is used to control filamentous organisms?
A) Polymer
B) Sulfur Dioxide
C) Coagulant
D) Chlorine
D) Chlorine (v.1 pg 399)
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
C) Flow and chlorine residual (v.1 pg 356)
Which toxic gas is commonly found in septic wastewater and smells like rotten eggs?
A) Hydrogen Sulfide
B) Carbon monoxide
C) Hydrogen
D) Carbon Dioxide
A) Hydrogen Sulfide (v.2 pg 299)
, What is the permissible exposure limit for chlorine gas vapor during a normal 8 hour workday and a
40 hour work week?
A) 0.1 ppm
B) 0.5 ppm
C) 1 ppm
D) 15 ppm
B) 0.5 ppm (v.2 pg 268)
What is a vulnerability assessment?
A) Assesses the impact of hydrogen sulfide to a concrete structure
B) Analyzes the impact of flow and infiltration problem to the plant hydraulics
C) Estimates the vulnerability of aquatic wildlife to excessive algae growth
D) Contingency planning to determine the vulnerability of the utility during various types of
emergencies and identify corrective actions to reduce the risks
D) Contingency planning to determine the vulnerability of the utility during various types of
emergencies and identify corrective actions to reduce the risks (v.2 pg 722)
What is the difference between the settling rate of activated sludge and raw sludge?
A) Activated sludge settles slightly faster than raw sludge
B) Activated sludge settles at the same rate as raw sludge
C) Activated sludge settles slower than raw sludge
D) Activated sludge settles much faster than raw sludge
C) Activated sludge settles slower than raw sludge (v.1 pg 109)
What should be mostly found in healthy activated sludge?
A) Tiny flagellates
B) Amoeboids
C) Short Filaments
D) Free swimmers and stalked ciliates
D) Free swimmers and stalked ciliates (v.2 pg 120,124)
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
A) Hydrogen, Nitrogen, Hydrogen sulfide, and other gases (v.2 pg 158)
What is true during the colder winter months?
A) Modify operations to decrease solids under aeration to provide less microorganisms to treat the
BOD
B) Modify operations to increase solids under aeration to provide more microorganisms to treat the
BOD
C) Biological activity will increase, which results in more overall sludge production
D) Microorganisms become more active
