,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%
Correct answer: C. 20 to 50%
What does the “F” in the 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
Correct answer: D. The food for the microorganisms flowing into the aeration tank, in
lbs/day
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
Correct answer: 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
Correct answer: D. Chlorine
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
Correct answer: C. Flow and chlorine residual
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
Correct answer: A. Hydrogen sulfide
What is the permissible exposure limit for chlorine gas vapor during a normal 8-hour workday
and 40-hour work week?
A. 0.1 ppm
B. 0.5 ppm
C. 1 ppm
D. 15 ppm
, Correct answer: B. 0.5 ppm
What is a vulnerability assessment?
A. Assesses the impact of hydrogen sulfide on concrete structures
B. Analyzes the impact of flow and infiltration on plant hydraulics
C. Estimates the vulnerability of aquatic wildlife to algae growth
D. Contingency planning to determine the vulnerability of the utility during emergencies and
identify corrective actions
Correct answer: D. Contingency planning to determine the vulnerability of the utility during
emergencies and identify corrective actions
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
Correct answer: C. Activated sludge settles slower than raw sludge
What should be mostly found in healthy activated sludge?
A. Tiny flagellates
B. Amoeboids
C. Short filaments
D. Free swimmers and stalked ciliates
Correct answer: D. Free swimmers and stalked ciliates
One to two percent of the digester gas in an anaerobic digester consists of:
A. Hydrogen, nitrogen, hydrogen sulfide, and other gases
A. 10 to 15%
B. 40 to 60%
C. 20 to 50%
D. 95 to 99%
Correct answer: C. 20 to 50%
What does the “F” in the 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
Correct answer: D. The food for the microorganisms flowing into the aeration tank, in
lbs/day
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
Correct answer: 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
Correct answer: D. Chlorine
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
Correct answer: C. Flow and chlorine residual
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
Correct answer: A. Hydrogen sulfide
What is the permissible exposure limit for chlorine gas vapor during a normal 8-hour workday
and 40-hour work week?
A. 0.1 ppm
B. 0.5 ppm
C. 1 ppm
D. 15 ppm
, Correct answer: B. 0.5 ppm
What is a vulnerability assessment?
A. Assesses the impact of hydrogen sulfide on concrete structures
B. Analyzes the impact of flow and infiltration on plant hydraulics
C. Estimates the vulnerability of aquatic wildlife to algae growth
D. Contingency planning to determine the vulnerability of the utility during emergencies and
identify corrective actions
Correct answer: D. Contingency planning to determine the vulnerability of the utility during
emergencies and identify corrective actions
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
Correct answer: C. Activated sludge settles slower than raw sludge
What should be mostly found in healthy activated sludge?
A. Tiny flagellates
B. Amoeboids
C. Short filaments
D. Free swimmers and stalked ciliates
Correct answer: D. Free swimmers and stalked ciliates
One to two percent of the digester gas in an anaerobic digester consists of:
A. Hydrogen, nitrogen, hydrogen sulfide, and other gases
