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Wastewater Treatment Operator Certification Test #2 NEWEST 2026
ACTUAL EXAM TEST- COMPLETE REAL EXAM QUESTIONS AND CORRECT
DETAILED ANSWERS (VERIFIED ANSWERS) ALREADY GRADED A+ (MOST
RECENT!!)
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% (v.1 pg 129)
QUESTION : 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 -
CORRECT ANSWER D) The food for the microorganisms flowing into
the aeration tank, in lbs/day (v.2 pg 58)
QUESTION : Which of the following describes the appearance of healthy
activated sludge?
A) Thick, greasy, dark tan foam
2026 2027 GRADED A+
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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
QUESTION : What is used to control filamentous organisms?
A) Polymer
B) Sulfur Dioxide
C) Coagulant
D) Chlorine - CORRECT ANSWER D) Chlorine (v.1 pg 399)
QUESTION : 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 (v.1
pg 356)
QUESTION : Which toxic gas is commonly found in septic wastewater and smells
like rotten eggs?
A) Hydrogen Sulfide
2026 2027 GRADED A+
, 3|Page
B) Carbon monoxide
C) Hydrogen
D) Carbon Dioxide - CORRECT ANSWER A) Hydrogen Sulfide (v.2 pg
299)
QUESTION : 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 - CORRECT ANSWER B) 0.5 ppm (v.2 pg 268)
QUESTION : 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 -
CORRECT ANSWER 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)
QUESTION : What is the difference between the settling rate of activated sludge
and raw sludge?
2026 2027 GRADED A+
Wastewater Treatment Operator Certification Test #2 NEWEST 2026
ACTUAL EXAM TEST- COMPLETE REAL EXAM QUESTIONS AND CORRECT
DETAILED ANSWERS (VERIFIED ANSWERS) ALREADY GRADED A+ (MOST
RECENT!!)
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% (v.1 pg 129)
QUESTION : 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 -
CORRECT ANSWER D) The food for the microorganisms flowing into
the aeration tank, in lbs/day (v.2 pg 58)
QUESTION : Which of the following describes the appearance of healthy
activated sludge?
A) Thick, greasy, dark tan foam
2026 2027 GRADED A+
,2|Page
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
QUESTION : What is used to control filamentous organisms?
A) Polymer
B) Sulfur Dioxide
C) Coagulant
D) Chlorine - CORRECT ANSWER D) Chlorine (v.1 pg 399)
QUESTION : 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 (v.1
pg 356)
QUESTION : Which toxic gas is commonly found in septic wastewater and smells
like rotten eggs?
A) Hydrogen Sulfide
2026 2027 GRADED A+
, 3|Page
B) Carbon monoxide
C) Hydrogen
D) Carbon Dioxide - CORRECT ANSWER A) Hydrogen Sulfide (v.2 pg
299)
QUESTION : 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 - CORRECT ANSWER B) 0.5 ppm (v.2 pg 268)
QUESTION : 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 -
CORRECT ANSWER 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)
QUESTION : What is the difference between the settling rate of activated sludge
and raw sludge?
2026 2027 GRADED A+
