BASIC WASTEWATER OPERATOR PRACTICE
EXAM CLASS 3 COMPLETE QUESTIONS
WITH 100% CORRECT ANSWERS
\Q\.What is the predominant organism in a healthy Activated Sludge Treatment
Plant? - ANSWERS✔-Stalked ciliates
\Q\.A composite sample must be? - ANSWERS✔-Representative and Sub-samples
time spaced over 15 minutes apart
\Q\.What is the standard volume for a BOD sample bottle? - ANSWERS✔-300ml
\Q\.If you have a lime slurry feed line, what is the best valve to use? - ANSWERS✔-
Plug valve
\Q\.If you notice a predominance of rotifers in your activated sludge sample while
looking at it under a microscope, what does this indicate? - ANSWERS✔-Old
Sludge
\Q\.If your activated sludge plant begins to nitrify, what conditions would you
expect to decrease? - ANSWERS✔-Settling in the clarifiers
,\Q\.Calculate the BOD given the information:
Initial DO: 8.3
Final DO: 5.9
Milliliters of sample used: 2 - ANSWERS✔-360mg/l
\Q\.How do you calibrate a chemical feed pump? - ANSWERS✔-By measuring the
pump output
\Q\.What is the chemical formula for sulfuric acid? - ANSWERS✔-H2SO4
\Q\.What is the most common type of Activated Sludge package plants? -
ANSWERS✔-extended aeration
\Q\.What is the most appropriate method of reducing the F:M Ratio? -
ANSWERS✔-Increase wasting
\Q\.An operator notices a portion of the aeration tank with large bubbles rising
up. What is the most likely problem? - ANSWERS✔-Unequal air distribution
caused by a blown diffuser
\Q\.What is suction lift? - ANSWERS✔-The pressure on the suction side of the
pump
, \Q\.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? - ANSWERS✔-22.5 mg/l
\Q\.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? -
ANSWERS✔-Decrease the lag time for pump operation by moving the floats closer
together
\Q\.What is the purpose of amber storage bottles? - ANSWERS✔-To protect
chemicals that are sensitive to light
\Q\.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 - ANSWERS✔-24 days
\Q\.How should a 1-ton chlorine cylinder be moved? - ANSWERS✔-Horizontal &
Horizontal
\Q\.Calculate F:M ratio
GIVEN: Influent BOD5 = 290mg/l
Influent Flow = 5.0MGD
Aeration basin MLSS = 2650 mg/l
EXAM CLASS 3 COMPLETE QUESTIONS
WITH 100% CORRECT ANSWERS
\Q\.What is the predominant organism in a healthy Activated Sludge Treatment
Plant? - ANSWERS✔-Stalked ciliates
\Q\.A composite sample must be? - ANSWERS✔-Representative and Sub-samples
time spaced over 15 minutes apart
\Q\.What is the standard volume for a BOD sample bottle? - ANSWERS✔-300ml
\Q\.If you have a lime slurry feed line, what is the best valve to use? - ANSWERS✔-
Plug valve
\Q\.If you notice a predominance of rotifers in your activated sludge sample while
looking at it under a microscope, what does this indicate? - ANSWERS✔-Old
Sludge
\Q\.If your activated sludge plant begins to nitrify, what conditions would you
expect to decrease? - ANSWERS✔-Settling in the clarifiers
,\Q\.Calculate the BOD given the information:
Initial DO: 8.3
Final DO: 5.9
Milliliters of sample used: 2 - ANSWERS✔-360mg/l
\Q\.How do you calibrate a chemical feed pump? - ANSWERS✔-By measuring the
pump output
\Q\.What is the chemical formula for sulfuric acid? - ANSWERS✔-H2SO4
\Q\.What is the most common type of Activated Sludge package plants? -
ANSWERS✔-extended aeration
\Q\.What is the most appropriate method of reducing the F:M Ratio? -
ANSWERS✔-Increase wasting
\Q\.An operator notices a portion of the aeration tank with large bubbles rising
up. What is the most likely problem? - ANSWERS✔-Unequal air distribution
caused by a blown diffuser
\Q\.What is suction lift? - ANSWERS✔-The pressure on the suction side of the
pump
, \Q\.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? - ANSWERS✔-22.5 mg/l
\Q\.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? -
ANSWERS✔-Decrease the lag time for pump operation by moving the floats closer
together
\Q\.What is the purpose of amber storage bottles? - ANSWERS✔-To protect
chemicals that are sensitive to light
\Q\.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 - ANSWERS✔-24 days
\Q\.How should a 1-ton chlorine cylinder be moved? - ANSWERS✔-Horizontal &
Horizontal
\Q\.Calculate F:M ratio
GIVEN: Influent BOD5 = 290mg/l
Influent Flow = 5.0MGD
Aeration basin MLSS = 2650 mg/l
