ADEQ WASTEWATER TREATMENT 1
EXAM QUESTIONS AND ANSWERS
2026/2027
Reason to use prechlorination at a wastewater treatment facility?
a. Decrease TSS load
b. Begin sterilization process
c. Inhibit growth of odor-producing bacteria
d. Promote settling of inorganic materials - ANSWERSInhibit growth of odor-producing
bacteria
The electrical current draw rate is measured in?
a. Volts
b. Amps
c. Ohms
d. Watts - ANSWERSAmps
All piping connections in a chlorine gas system should be checked for leaks by:
a. Pressure gauge
b. Ammonia vapors near connections
c. Misting water
d. Looking for signs of corrosion - ANSWERSAmmonia vapors near connections
Improper use or lack of backflow preventers may create:
a. Increased water pressure
b. Low water pressure
c. Contamination
d. Fluctuating water pressure - ANSWERSContamination
Tool to check bearings on an electrical motor?
a. Tachometer
b. Stethoscope
c. Vibration meter
d. Oscilloscope - ANSWERSVibration meter
Longest life seal under normal conditions?
a. Mechanical seal
b. Water seal
c. Packing seal
d. Gland seal - ANSWERSMechanical seal
pH test with an electrode?
,a. Raise temperature to 40°C
b. Lower temperature to 2°C
c. Dechlorinate
d. Maintain constant stirring rate - ANSWERSMaintain constant stirring rate
Dry chemical feeder: 2.65 lbs in 5 minutes. What is the rate?
a. 13 lbs/day
b. 763 lbs/day
c. 3883 lbs/day
d. 48,203 lbs/day - ANSWERS763 lbs/day
Changing oil every 1000 hours is what type of maintenance?
a. Preventative
b. Reactive
c. Run-to-failure
d. Conditional - ANSWERSPreventative
Sludge sample test for MLSS?
a. Remix
b. Filter
c. Allow to stand
d. Acidity - ANSWERSFilter
Minimum DO level test time on a facultative lagoon?
a. 5 am
b. 11 am
c. 5 pm
d. 11 pm - ANSWERS5 am
Which form of solids is MOST difficult to remove in a gravity treatment process?
a. Coagulant
b. Precipitated
c. Colloids - ANSWERSColloids
A greasy scummy layer of deep tan or dark brown foam on an aerator tank is MOST
likely due to:
a. Old mixed liquor solids
b. Young mixed liquor solids
c. Plant received toxic load
d. Brown color indicates everything is dying - ANSWERSOld mixed liquor solids
MOST commonly used to determine stabilization of solids in an aerobic digester?
a. Methane gas production
b. Volatile acid alkalinity ratio
c. Specific oxygen uptake rate
d. VSI - ANSWERSSpecific oxygen uptake rate
, Primary objective of the industrial pretreatment program?
a. Ensure industrial users receive adequate water supply
b. Attract industrial users to the community
c. Eliminate discharge from industrial users
d. Regulate discharge from industrial users - ANSWERSRegulate discharge from
industrial users
Raw wastewater CBOD concentration of 450 ppm, most likely due to:
a. High organic load
b. Low organic load
c. Septic condition
d. Alkaline condition - ANSWERSHigh organic load
A sample of effluent collected from an aerated lagoon at 2:15 PM on a sunny July day
shows: DO is 20 mg/L, pH is 8.8, and the lagoon is bright green. Aerators are not
running. What is the MOST appropriate action?
a. Keep aerators off
b. Apply algaecide
c. Apply sulfuric acid
d. Turn aerators on - ANSWERSKeep aerators off
MOST likely cause of short-circuiting in a tank?
a. High incoming BOD
b. Missing baffle
c. Low flow
d. Increased detention time - ANSWERSMissing baffle
The activated sludge process is turbid. A microscopic examination shows:
60% rotifers (old sludge)
30% nematodes (old sludge)
10% stalked colonizers
What action should be taken?
a. Increase aeration
b. Increase WAS
c. Decrease aeration
d. Decrease WAS - ANSWERSIncrease WAS
A plant used sixty 55-gallon drums of sodium hypochlorite during 1 year of operation.
The average withdrawal from each drum was 50 gallons. What was the total amount
used during the year?
a. 3,000 gallons
b. 3,300 gallons
c. 4,000 gallons
d. 4,300 gallons - ANSWERS3,000 gallons
EXAM QUESTIONS AND ANSWERS
2026/2027
Reason to use prechlorination at a wastewater treatment facility?
a. Decrease TSS load
b. Begin sterilization process
c. Inhibit growth of odor-producing bacteria
d. Promote settling of inorganic materials - ANSWERSInhibit growth of odor-producing
bacteria
The electrical current draw rate is measured in?
a. Volts
b. Amps
c. Ohms
d. Watts - ANSWERSAmps
All piping connections in a chlorine gas system should be checked for leaks by:
a. Pressure gauge
b. Ammonia vapors near connections
c. Misting water
d. Looking for signs of corrosion - ANSWERSAmmonia vapors near connections
Improper use or lack of backflow preventers may create:
a. Increased water pressure
b. Low water pressure
c. Contamination
d. Fluctuating water pressure - ANSWERSContamination
Tool to check bearings on an electrical motor?
a. Tachometer
b. Stethoscope
c. Vibration meter
d. Oscilloscope - ANSWERSVibration meter
Longest life seal under normal conditions?
a. Mechanical seal
b. Water seal
c. Packing seal
d. Gland seal - ANSWERSMechanical seal
pH test with an electrode?
,a. Raise temperature to 40°C
b. Lower temperature to 2°C
c. Dechlorinate
d. Maintain constant stirring rate - ANSWERSMaintain constant stirring rate
Dry chemical feeder: 2.65 lbs in 5 minutes. What is the rate?
a. 13 lbs/day
b. 763 lbs/day
c. 3883 lbs/day
d. 48,203 lbs/day - ANSWERS763 lbs/day
Changing oil every 1000 hours is what type of maintenance?
a. Preventative
b. Reactive
c. Run-to-failure
d. Conditional - ANSWERSPreventative
Sludge sample test for MLSS?
a. Remix
b. Filter
c. Allow to stand
d. Acidity - ANSWERSFilter
Minimum DO level test time on a facultative lagoon?
a. 5 am
b. 11 am
c. 5 pm
d. 11 pm - ANSWERS5 am
Which form of solids is MOST difficult to remove in a gravity treatment process?
a. Coagulant
b. Precipitated
c. Colloids - ANSWERSColloids
A greasy scummy layer of deep tan or dark brown foam on an aerator tank is MOST
likely due to:
a. Old mixed liquor solids
b. Young mixed liquor solids
c. Plant received toxic load
d. Brown color indicates everything is dying - ANSWERSOld mixed liquor solids
MOST commonly used to determine stabilization of solids in an aerobic digester?
a. Methane gas production
b. Volatile acid alkalinity ratio
c. Specific oxygen uptake rate
d. VSI - ANSWERSSpecific oxygen uptake rate
, Primary objective of the industrial pretreatment program?
a. Ensure industrial users receive adequate water supply
b. Attract industrial users to the community
c. Eliminate discharge from industrial users
d. Regulate discharge from industrial users - ANSWERSRegulate discharge from
industrial users
Raw wastewater CBOD concentration of 450 ppm, most likely due to:
a. High organic load
b. Low organic load
c. Septic condition
d. Alkaline condition - ANSWERSHigh organic load
A sample of effluent collected from an aerated lagoon at 2:15 PM on a sunny July day
shows: DO is 20 mg/L, pH is 8.8, and the lagoon is bright green. Aerators are not
running. What is the MOST appropriate action?
a. Keep aerators off
b. Apply algaecide
c. Apply sulfuric acid
d. Turn aerators on - ANSWERSKeep aerators off
MOST likely cause of short-circuiting in a tank?
a. High incoming BOD
b. Missing baffle
c. Low flow
d. Increased detention time - ANSWERSMissing baffle
The activated sludge process is turbid. A microscopic examination shows:
60% rotifers (old sludge)
30% nematodes (old sludge)
10% stalked colonizers
What action should be taken?
a. Increase aeration
b. Increase WAS
c. Decrease aeration
d. Decrease WAS - ANSWERSIncrease WAS
A plant used sixty 55-gallon drums of sodium hypochlorite during 1 year of operation.
The average withdrawal from each drum was 50 gallons. What was the total amount
used during the year?
a. 3,000 gallons
b. 3,300 gallons
c. 4,000 gallons
d. 4,300 gallons - ANSWERS3,000 gallons
