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Wastewater Treatment Operator Certification Test #1 latest
update 2026/2027
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 Correct 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 Correct 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 Correct 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% Correct 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. Correct Answer: C) Scum causes more piping problems than other substances pumped at a wastewater treatment
plant. (v.2 pg 449)
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