WASTEWATER OPERATOR 2026 TEST PAPER QUESTIONS
AND ANSWERS RATED A+
✔✔What is the most common type of activated sludge package plants?
a. extended aeration
b. sequential batch reactor
c. oxidation ditch
d. bardenpho - ✔✔a. extended aeration
✔✔What is the most appropriate method of reducing the F:M ratio?
A. increase wasting
b. decrease wasting
c. reduce BOD from influent flow
D. add polymer to RAS to increase settling - ✔✔b. decrease wasting
✔✔An operator notices a portion of the aeration tank with large bubbles rising up. What
is the most likely problem?
a. equal air distribution
b. unequal air distribution caused by a blown/clogged diffuser
c. normal operation
d. reason to believe the air filter in the blower is clogged - ✔✔b. unequal air distribution
caused by a blown diffuser
✔✔What is suction lift?
a. a team approach to lifting heavy objects
b. the pressure on the suction side of the pump
c. the measurement of liquid pressure at the pump
d. the measure of how bad your workers lift heavy objects - ✔✔b. 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?
A. 290 mg/L
b. 60 mg/L
c. 30 mg/L
d. 22.5 mg/L - ✔✔d. 22.5 mg/L
✔✔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?
,A. decrease the lag time for pump operation by moving the floats closer together
b. add pH adjuster to the influent flow
c. install larger capacity pumps in the lift stations
d. the her nothing you can do to correct this problem - ✔✔A. decrease the lag time for
pump operation by moving the floats closer together
✔✔What is the purpose of amber storage bottles?
A. the color is pretty
b. they are cheaper
c. to protect chemicals that are sensitive to light
d. so you can not see what is inside the container - ✔✔c. to protect chemicals that are
sensitive to light
✔✔Calculate SRT
Given: MLSS = 2400 mg/L
Aeration basin volume = 35,000 gallons = 0.0350 MG
WAS concentration = 3500 mg/L
WAS flow rate = 0.001 MGD
A. 6 hours
b. 6 days
c. 24 hours
d. 24 days - ✔✔d. 24 days
✔✔How should a 1-ton chlorine cylinder be moved and stored?
A. Horizontal and vertical
B. vertical and horizontal
C. vertical and vertical
D. horizontal and horizontal - ✔✔D. horizontal and horizontal
✔✔Calculate F:M ratio
Given: Influent BOD5 = 290 mg/L
Influent flow = 5.0 MGD
Aeration basin MLSS = 2650 mg/L
Aeration basin volume = 0.8 MG
A. 0.01
B. 0.11
C. 0.68
D. 0.06 - ✔✔c. 0.68
, ✔✔What would most likely cause a submersible pump to an AMP reading that is above
the optimum level?
A. nothing, pumps normally run highs AMPs
b. clogged impeller
c. low voltage at power supply
d. low flow to pump station - ✔✔b. clogged impeller
✔✔Which of the following are non-moving parts of a running motor?
A. impeller
b. shaft
c.windings
d. stator - ✔✔d. stator
✔✔Calculate SVI
Given: 30 minute settling test = 1800 mL in a 2000 mL container
MLSS = 4000 mg/L
A. 200
b. 450
c. 225
d. 115 - ✔✔c. 225
✔✔What type of flow meters are used during normal operations of the sludge removal?
a. turbine
b. magnetic
c. TDR
d. paddle wheel - ✔✔b. magnetic
✔✔What should be done when the bioreactor in an SBR plant is organically
overloaded?
a. nothing - it is normal for bioreactors to be organically overloaded
b. waste more sludge
c. add more fresh water
d. increase effluent flow - ✔✔b. waste more sludge
✔✔Why are approved black flow devices installed above ground level?
a. ease of access
b. because the plummers union requires it
c. cost of vault
d. to keep valves from being submerged - ✔✔d. to keep valves from being submerged
AND ANSWERS RATED A+
✔✔What is the most common type of activated sludge package plants?
a. extended aeration
b. sequential batch reactor
c. oxidation ditch
d. bardenpho - ✔✔a. extended aeration
✔✔What is the most appropriate method of reducing the F:M ratio?
A. increase wasting
b. decrease wasting
c. reduce BOD from influent flow
D. add polymer to RAS to increase settling - ✔✔b. decrease wasting
✔✔An operator notices a portion of the aeration tank with large bubbles rising up. What
is the most likely problem?
a. equal air distribution
b. unequal air distribution caused by a blown/clogged diffuser
c. normal operation
d. reason to believe the air filter in the blower is clogged - ✔✔b. unequal air distribution
caused by a blown diffuser
✔✔What is suction lift?
a. a team approach to lifting heavy objects
b. the pressure on the suction side of the pump
c. the measurement of liquid pressure at the pump
d. the measure of how bad your workers lift heavy objects - ✔✔b. 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?
A. 290 mg/L
b. 60 mg/L
c. 30 mg/L
d. 22.5 mg/L - ✔✔d. 22.5 mg/L
✔✔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?
,A. decrease the lag time for pump operation by moving the floats closer together
b. add pH adjuster to the influent flow
c. install larger capacity pumps in the lift stations
d. the her nothing you can do to correct this problem - ✔✔A. decrease the lag time for
pump operation by moving the floats closer together
✔✔What is the purpose of amber storage bottles?
A. the color is pretty
b. they are cheaper
c. to protect chemicals that are sensitive to light
d. so you can not see what is inside the container - ✔✔c. to protect chemicals that are
sensitive to light
✔✔Calculate SRT
Given: MLSS = 2400 mg/L
Aeration basin volume = 35,000 gallons = 0.0350 MG
WAS concentration = 3500 mg/L
WAS flow rate = 0.001 MGD
A. 6 hours
b. 6 days
c. 24 hours
d. 24 days - ✔✔d. 24 days
✔✔How should a 1-ton chlorine cylinder be moved and stored?
A. Horizontal and vertical
B. vertical and horizontal
C. vertical and vertical
D. horizontal and horizontal - ✔✔D. horizontal and horizontal
✔✔Calculate F:M ratio
Given: Influent BOD5 = 290 mg/L
Influent flow = 5.0 MGD
Aeration basin MLSS = 2650 mg/L
Aeration basin volume = 0.8 MG
A. 0.01
B. 0.11
C. 0.68
D. 0.06 - ✔✔c. 0.68
, ✔✔What would most likely cause a submersible pump to an AMP reading that is above
the optimum level?
A. nothing, pumps normally run highs AMPs
b. clogged impeller
c. low voltage at power supply
d. low flow to pump station - ✔✔b. clogged impeller
✔✔Which of the following are non-moving parts of a running motor?
A. impeller
b. shaft
c.windings
d. stator - ✔✔d. stator
✔✔Calculate SVI
Given: 30 minute settling test = 1800 mL in a 2000 mL container
MLSS = 4000 mg/L
A. 200
b. 450
c. 225
d. 115 - ✔✔c. 225
✔✔What type of flow meters are used during normal operations of the sludge removal?
a. turbine
b. magnetic
c. TDR
d. paddle wheel - ✔✔b. magnetic
✔✔What should be done when the bioreactor in an SBR plant is organically
overloaded?
a. nothing - it is normal for bioreactors to be organically overloaded
b. waste more sludge
c. add more fresh water
d. increase effluent flow - ✔✔b. waste more sludge
✔✔Why are approved black flow devices installed above ground level?
a. ease of access
b. because the plummers union requires it
c. cost of vault
d. to keep valves from being submerged - ✔✔d. to keep valves from being submerged
