1|Page
VIRGINIA WASTEWATER WORKS OPERATOR CLASS
3 EXAMINATION COMPLETE VERIFIED QUESTIONS
AND DETAILED SOLUTIONS LATEST UPDATE THIS
YEAR JUST RELEASED
If you notice a predominance of rotifers in your activated
sludge sample while looking at it under a microscope,
what does this indicate? - Answer-Old Sludge
If your activated sludge plant begins to nitrify, what
conditions would you expect to decrease? - Answer-
Settling in the clarifiers
Calculate the BOD given the information:
Initial DO: 8.3
Final DO: 5.9
Milliliters of sample used: 2 - Answer-360mg/l
How do you calibrate a chemical feed pump? - Answer-By
measuring the pump output
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What is the chemical formula for sulfuric acid? - Answer-
H2SO4
What is the most common type of Activated Sludge
package plants? - Answer-extended aeration
What is the most appropriate method of reducing the F:M
Ratio? - Answer-Increase wasting
An operator notices a portion of the aeration tank with
large bubbles rising up. What is the most likely problem? -
Answer-Unequal air distribution caused by a blown diffuser
What is suction lift? - Answer-The pressure on the suction
side of the pump
The primary effluent to a RBC system is 350 mg/l BOD.
The primary unit removes 83%, the secondary unit
removes 50%, and the final unit removes 25%. What is the
BOD leaving the final unit of the RBC train? - Answer-22.5
mg/l
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The influent to the treatment plant is septic. It is
determined that it is coming from a lift station upstream
from the plant. What should the operator do? - Answer-
Decrease the lag time for pump operation by moving the
floats closer together
What is the purpose of amber storage bottles? - Answer-
To protect chemicals that are sensitive to light
Calculate SRT
GIVEN: Mixed liquor suspended solids (MLSS) = 2400mg/l
Aeration basin volume = 35,000 gallons = 0.0350 million
gallons (MG)
Waste activated sludge (WAS) concentration = 3500mg/l
Waste activated sludge (WAS) flowrate = 0.001MGD -
Answer-24 days
How should a 1-ton chlorine cylinder be moved? - Answer-
Horizontal & Horizontal
Calculate F:M ratio
GIVEN: Influent BOD5 = 290mg/l
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Influent Flow = 5.0MGD
Aeration basin MLSS = 2650 mg/l
Aeration basin volume = 0.8MG - Answer-0.68
What is the predominant organism in a healthy Activated
Sludge Treatment Plant? - Answer-Stalked ciliates
A composite sample must be? - Answer-Representative
and Sub-samples time spaced over 15 minutes apart
What is the standard volume for a BOD sample bottle? -
Answer-300ml
If you have a lime slurry feed line, what is the best valve to
use? - Answer-Plug valve
What would most likely cause a submersible pump to have
an AMP reading that is above the optimum level? -
Answer-Clogged impeller
Which of the following are non-moving parts of a running
motor? - Answer-Stator
VIRGINIA WASTEWATER WORKS OPERATOR CLASS
3 EXAMINATION COMPLETE VERIFIED QUESTIONS
AND DETAILED SOLUTIONS LATEST UPDATE THIS
YEAR JUST RELEASED
If you notice a predominance of rotifers in your activated
sludge sample while looking at it under a microscope,
what does this indicate? - Answer-Old Sludge
If your activated sludge plant begins to nitrify, what
conditions would you expect to decrease? - Answer-
Settling in the clarifiers
Calculate the BOD given the information:
Initial DO: 8.3
Final DO: 5.9
Milliliters of sample used: 2 - Answer-360mg/l
How do you calibrate a chemical feed pump? - Answer-By
measuring the pump output
,2|Page
What is the chemical formula for sulfuric acid? - Answer-
H2SO4
What is the most common type of Activated Sludge
package plants? - Answer-extended aeration
What is the most appropriate method of reducing the F:M
Ratio? - Answer-Increase wasting
An operator notices a portion of the aeration tank with
large bubbles rising up. What is the most likely problem? -
Answer-Unequal air distribution caused by a blown diffuser
What is suction lift? - Answer-The pressure on the suction
side of the pump
The primary effluent to a RBC system is 350 mg/l BOD.
The primary unit removes 83%, the secondary unit
removes 50%, and the final unit removes 25%. What is the
BOD leaving the final unit of the RBC train? - Answer-22.5
mg/l
,3|Page
The influent to the treatment plant is septic. It is
determined that it is coming from a lift station upstream
from the plant. What should the operator do? - Answer-
Decrease the lag time for pump operation by moving the
floats closer together
What is the purpose of amber storage bottles? - Answer-
To protect chemicals that are sensitive to light
Calculate SRT
GIVEN: Mixed liquor suspended solids (MLSS) = 2400mg/l
Aeration basin volume = 35,000 gallons = 0.0350 million
gallons (MG)
Waste activated sludge (WAS) concentration = 3500mg/l
Waste activated sludge (WAS) flowrate = 0.001MGD -
Answer-24 days
How should a 1-ton chlorine cylinder be moved? - Answer-
Horizontal & Horizontal
Calculate F:M ratio
GIVEN: Influent BOD5 = 290mg/l
, 4|Page
Influent Flow = 5.0MGD
Aeration basin MLSS = 2650 mg/l
Aeration basin volume = 0.8MG - Answer-0.68
What is the predominant organism in a healthy Activated
Sludge Treatment Plant? - Answer-Stalked ciliates
A composite sample must be? - Answer-Representative
and Sub-samples time spaced over 15 minutes apart
What is the standard volume for a BOD sample bottle? -
Answer-300ml
If you have a lime slurry feed line, what is the best valve to
use? - Answer-Plug valve
What would most likely cause a submersible pump to have
an AMP reading that is above the optimum level? -
Answer-Clogged impeller
Which of the following are non-moving parts of a running
motor? - Answer-Stator
