2024 BASIC WASTEWATER
OPERATOR PRACTICE EXAM WITH
CORRECT ANSWERS
What is the predominant organism in a healthy activated sludge treatment
plant?
A. Stalked ciliates
B. rotifers
C. nematodes
D. amoebas - CORRECT-ANSWERSA. Stalked Ciliates
What part of a chlorine cylinder is designed to melt at 150 to 160 degrees F
to prevent the cylinder from exploding in the event of a fire?
a. mucus plug
b. fusible plug
c. cork stopper
d. fire plug - CORRECT-ANSWERSb. fusible plug
What would be the operator's first indicator when a high organic waste load
reaches an activated sludge plant?
a. decrease in the dissolved oxygen, D.O. residual in the reactors aeration
tanks
b. a call from the industry discharging the waste
c. purple water at the influent
d. green water at the influent - CORRECT-ANSWERSa. decrease in the
dissolved oxygen, D.O. residual in the reactors aeration tanks
What causes turbidity in wastewater?
a. turds
b. toilet paper
c. finely divided suspended material
d. corn and peanuts - CORRECT-ANSWERSc. finely divided suspended
material
What gas is most commonly associated with septic wastewater?
,a. ethanol
b. alcohol
c. methane
d. hydrogen sulfide - CORRECT-ANSWERSd. hydrogen sulfide
Why is mechanical ventilation of a lift station required?
a. to minimize the presence of harmful gases
b. it is not
c. to allow for easy access to the pit
d. because the EPD requires it - CORRECT-ANSWERSa. to minimize the
presence of harmful gases
How is voltage reduced when required in electrical circuits?
a. a transformer is used
b. drop one leg of the power coming in
c. add a leg to the power supply
d. a generator is used - CORRECT-ANSWERSa. a transformer is used
What will occur if the bearings on horizontal centrifugal pumps are over
lubricated?
a. may cause overheating and possible failure of the bearings
b. it is impossible to over lubricate the bearings on horizontal centrifugal
pumps
c. horizontal centrifugal pumps do not have bearings
d. the bearings on horizontal centrifugal pumps are sealed and do not
require lubrication - CORRECT-ANSWERSa. may cause overheating and
possible failure of the bearings
What is the most likely cause of rising sludge in clarifiers?
a. young sludge
b. old sludge
c. middle age sludge
d. slime - CORRECT-ANSWERSb. old sludge
the amount of BOD in sludge entering a digester would be an indirect
measure of what in the digester?
a. plant matter
b. food
c. oxygen
d. microorganisms - CORRECT-ANSWERSb. food
, How can chemical coagulation dose be initially estimated?
a. trial and error
b. jar test
c. bucket test
d. SWAG - CORRECT-ANSWERSb. jar test
What type of equipment should be calibrated daily at the treatment plants?
a. portable DO probe/meter
b. AMP meter
c. rain gauge
d. staff gauge - CORRECT-ANSWERSa. portable DO probe/meter
What is the ash content remaining at the end of a VSS test equal to?
a. inorganic solids
b. organic solids
c. semi-volatile organics
d. volatile organic compounds - CORRECT-ANSWERSa. inorganic solids
What does a chlorine demand test indicate?
a. the amount of chlorine required to give a desired chlorine residual after a
given time
b. the amount of chlorine required to give a desired chlorine dosage after a
given time
c. the amount of chlorine required to meet EPD requirements
d. the amount of chlorine required to give chlorine residual after 15 minutes -
CORRECT-ANSWERSa. the amount of chlorine required to give a desired
chlorine residual after a given time
What coats granular filter media with a biological slime used to filter
wastewater?
a. biological slime composed of soluble BOD and ammonia
b. detritus
c. grease
d. clay - CORRECT-ANSWERSa. biological slime composed of soluble BOD and
ammonia
In the membrane filter method how is the number of coliforms estimated?
a. by the number of yellow wells
b. by counting the blue/green colonies that appear on the filter after
incubation
OPERATOR PRACTICE EXAM WITH
CORRECT ANSWERS
What is the predominant organism in a healthy activated sludge treatment
plant?
A. Stalked ciliates
B. rotifers
C. nematodes
D. amoebas - CORRECT-ANSWERSA. Stalked Ciliates
What part of a chlorine cylinder is designed to melt at 150 to 160 degrees F
to prevent the cylinder from exploding in the event of a fire?
a. mucus plug
b. fusible plug
c. cork stopper
d. fire plug - CORRECT-ANSWERSb. fusible plug
What would be the operator's first indicator when a high organic waste load
reaches an activated sludge plant?
a. decrease in the dissolved oxygen, D.O. residual in the reactors aeration
tanks
b. a call from the industry discharging the waste
c. purple water at the influent
d. green water at the influent - CORRECT-ANSWERSa. decrease in the
dissolved oxygen, D.O. residual in the reactors aeration tanks
What causes turbidity in wastewater?
a. turds
b. toilet paper
c. finely divided suspended material
d. corn and peanuts - CORRECT-ANSWERSc. finely divided suspended
material
What gas is most commonly associated with septic wastewater?
,a. ethanol
b. alcohol
c. methane
d. hydrogen sulfide - CORRECT-ANSWERSd. hydrogen sulfide
Why is mechanical ventilation of a lift station required?
a. to minimize the presence of harmful gases
b. it is not
c. to allow for easy access to the pit
d. because the EPD requires it - CORRECT-ANSWERSa. to minimize the
presence of harmful gases
How is voltage reduced when required in electrical circuits?
a. a transformer is used
b. drop one leg of the power coming in
c. add a leg to the power supply
d. a generator is used - CORRECT-ANSWERSa. a transformer is used
What will occur if the bearings on horizontal centrifugal pumps are over
lubricated?
a. may cause overheating and possible failure of the bearings
b. it is impossible to over lubricate the bearings on horizontal centrifugal
pumps
c. horizontal centrifugal pumps do not have bearings
d. the bearings on horizontal centrifugal pumps are sealed and do not
require lubrication - CORRECT-ANSWERSa. may cause overheating and
possible failure of the bearings
What is the most likely cause of rising sludge in clarifiers?
a. young sludge
b. old sludge
c. middle age sludge
d. slime - CORRECT-ANSWERSb. old sludge
the amount of BOD in sludge entering a digester would be an indirect
measure of what in the digester?
a. plant matter
b. food
c. oxygen
d. microorganisms - CORRECT-ANSWERSb. food
, How can chemical coagulation dose be initially estimated?
a. trial and error
b. jar test
c. bucket test
d. SWAG - CORRECT-ANSWERSb. jar test
What type of equipment should be calibrated daily at the treatment plants?
a. portable DO probe/meter
b. AMP meter
c. rain gauge
d. staff gauge - CORRECT-ANSWERSa. portable DO probe/meter
What is the ash content remaining at the end of a VSS test equal to?
a. inorganic solids
b. organic solids
c. semi-volatile organics
d. volatile organic compounds - CORRECT-ANSWERSa. inorganic solids
What does a chlorine demand test indicate?
a. the amount of chlorine required to give a desired chlorine residual after a
given time
b. the amount of chlorine required to give a desired chlorine dosage after a
given time
c. the amount of chlorine required to meet EPD requirements
d. the amount of chlorine required to give chlorine residual after 15 minutes -
CORRECT-ANSWERSa. the amount of chlorine required to give a desired
chlorine residual after a given time
What coats granular filter media with a biological slime used to filter
wastewater?
a. biological slime composed of soluble BOD and ammonia
b. detritus
c. grease
d. clay - CORRECT-ANSWERSa. biological slime composed of soluble BOD and
ammonia
In the membrane filter method how is the number of coliforms estimated?
a. by the number of yellow wells
b. by counting the blue/green colonies that appear on the filter after
incubation
