WasteWater Operator class C exam practice review 2026/2027
version verified with correct answers newly updated
You suspect your anaerobic digester is going sour. What is the best way to verify its
condition?
A. pH
B. Foam type
C. VA/ALK ratio
D. DO- answer>>> >>>C. VA/ALK ratio
Before operating any piece of equipment what should be done?
A. Lock out Tag out (remember, safety first!)
B. Read O & M manual
C. Read manufacturers manual
D. Notify supervisor- answer>>> >>>C. Read manufacturers manual
Detritus is noticed in your grit channel. What is the problem?
A. Velocity too fast with short D/T
B. Velocity too low with long D/T
C. Short circuiting
D. Density currents- answer>>> >>>B. Velocity too low with long D/T
What is considered normal operation of an aerobic digester?
A. Fill react
B. Skim off foam when needed
C. Settle and Decant as needed
D. Feed only during low flow or constant when the sun is out- answer>>> >>>C. Settle
and Decant as needed
A plant with a flow of 1 MGD should be monitored
A. Continuously
B. Intermittently
C. Daily
D. Every four hours depending on surface load- answer>>> >>>A. Continuously
What do total solids consist of?
A. Dissolved and settleable
B. Floatable and settlable
C. Suspended and dissolved
,D. Settlable and nonsettleable- answer>>> >>>C. Suspended and dissolved
What would cause excessive wear on bearing?
A. Misalignment
B. Reduced Oil due to low viscosity
C. Blow seal
D. Over tubercation- answer>>> >>>A. Misalignment
Amperometric titration is used to measure
A. Dissolved solids
B. Chlorine residual
C. Colloids
D. Emulsions- answer>>> >>>B. Chlorine residual
What growth phase is an aerobic digester operated in.
A. Log
B. Lag
C. Endogenous respiration
D. Declining phase- answer>>> >>>C. Endogenous respiration
If excessive pressure builds up in a chlorine tank due to excessive heat. What will
prevent explosions?
A. Valve seat adjustments
B. Heat reducing valve
C. Fusible plug
D. Check valve- answer>>> >>>C. Fusible plug
You notice that your bearings are excessively hot on a pump, why?
A. Ambient temperature too high
B. Over lubrication
C. Oil seal blown
D. Discharge rate too low- answer>>> >>>B. Over lubrication
Where can you gain access for collection system maintenance?
A. Lift station
B. Force main
C. Man hole
D. Gravity main- answer>>> >>>C. Man hole
Low DO and nutrient deficiency will promote the growth of what?
, A. Rotifers
B. Filamentous bacteria
C. Spirillium
D. Amoebas- answer>>> >>>B. Filamentous bacteria
When charging a lead-acid type battery for a composite sampler, what dangerous gas
could be produced?
A. Hydrogen
B. Oxygen
C. Hydrogen sulfide
D. Cyanide- answer>>> >>>A. Hydrogen
What is the best method in dealing with a chemical spill?
A. Contain and clean up
B. Saw dust and kitty litter
C. Foam congaing super trimethyl bromine
D. Flood with water- answer>>> >>>A. Contain and clean up
There is septic wastewater entering your primary clarifier. What is the problem?
A. Aerobic conditions in the collections system
B. Lift station pumps operating on short cycles
C. Anaerobic conditions in the collections systems
D. High flows due to a low MCRT- answer>>> >>>C. Anaerobic condition in the
collections system
Which of the following substances is highly viscous and very slippery?
A. Calcium hypochlorite
B. Calcium oxide
C. Potassium permanganate
D. Polymer- answer>>> >>>D. Polymer
If you pump green sludge to a drying bed what chemical should be applied?
A. Polymer
B. Lime
C. Cl2
D. Alum- answer>>> >>>B. Lime
Chlorine leaks can be detected by?
A. ISCBA
version verified with correct answers newly updated
You suspect your anaerobic digester is going sour. What is the best way to verify its
condition?
A. pH
B. Foam type
C. VA/ALK ratio
D. DO- answer>>> >>>C. VA/ALK ratio
Before operating any piece of equipment what should be done?
A. Lock out Tag out (remember, safety first!)
B. Read O & M manual
C. Read manufacturers manual
D. Notify supervisor- answer>>> >>>C. Read manufacturers manual
Detritus is noticed in your grit channel. What is the problem?
A. Velocity too fast with short D/T
B. Velocity too low with long D/T
C. Short circuiting
D. Density currents- answer>>> >>>B. Velocity too low with long D/T
What is considered normal operation of an aerobic digester?
A. Fill react
B. Skim off foam when needed
C. Settle and Decant as needed
D. Feed only during low flow or constant when the sun is out- answer>>> >>>C. Settle
and Decant as needed
A plant with a flow of 1 MGD should be monitored
A. Continuously
B. Intermittently
C. Daily
D. Every four hours depending on surface load- answer>>> >>>A. Continuously
What do total solids consist of?
A. Dissolved and settleable
B. Floatable and settlable
C. Suspended and dissolved
,D. Settlable and nonsettleable- answer>>> >>>C. Suspended and dissolved
What would cause excessive wear on bearing?
A. Misalignment
B. Reduced Oil due to low viscosity
C. Blow seal
D. Over tubercation- answer>>> >>>A. Misalignment
Amperometric titration is used to measure
A. Dissolved solids
B. Chlorine residual
C. Colloids
D. Emulsions- answer>>> >>>B. Chlorine residual
What growth phase is an aerobic digester operated in.
A. Log
B. Lag
C. Endogenous respiration
D. Declining phase- answer>>> >>>C. Endogenous respiration
If excessive pressure builds up in a chlorine tank due to excessive heat. What will
prevent explosions?
A. Valve seat adjustments
B. Heat reducing valve
C. Fusible plug
D. Check valve- answer>>> >>>C. Fusible plug
You notice that your bearings are excessively hot on a pump, why?
A. Ambient temperature too high
B. Over lubrication
C. Oil seal blown
D. Discharge rate too low- answer>>> >>>B. Over lubrication
Where can you gain access for collection system maintenance?
A. Lift station
B. Force main
C. Man hole
D. Gravity main- answer>>> >>>C. Man hole
Low DO and nutrient deficiency will promote the growth of what?
, A. Rotifers
B. Filamentous bacteria
C. Spirillium
D. Amoebas- answer>>> >>>B. Filamentous bacteria
When charging a lead-acid type battery for a composite sampler, what dangerous gas
could be produced?
A. Hydrogen
B. Oxygen
C. Hydrogen sulfide
D. Cyanide- answer>>> >>>A. Hydrogen
What is the best method in dealing with a chemical spill?
A. Contain and clean up
B. Saw dust and kitty litter
C. Foam congaing super trimethyl bromine
D. Flood with water- answer>>> >>>A. Contain and clean up
There is septic wastewater entering your primary clarifier. What is the problem?
A. Aerobic conditions in the collections system
B. Lift station pumps operating on short cycles
C. Anaerobic conditions in the collections systems
D. High flows due to a low MCRT- answer>>> >>>C. Anaerobic condition in the
collections system
Which of the following substances is highly viscous and very slippery?
A. Calcium hypochlorite
B. Calcium oxide
C. Potassium permanganate
D. Polymer- answer>>> >>>D. Polymer
If you pump green sludge to a drying bed what chemical should be applied?
A. Polymer
B. Lime
C. Cl2
D. Alum- answer>>> >>>B. Lime
Chlorine leaks can be detected by?
A. ISCBA
