WASTEWATER OPERATOR CLASS 1 & 2 PRACTICE
EXAM 350 QUESTIONS & CORRECT ANSWERS
LATEST 2026/2027
In the formula Q=V(A), Q is defined as rate of flow expressed as? - ANSWER-Cu.
Ft. / sec.
What is the primary objective of the Clean Water Act of 1972? - ANSWER-
Restore and maintain the chemical, physical, and biological integrity of water in
the US
When cells use their own protoplasm and start to eat each other, as food to provide
the energy to maintain life, this is known as what type of growth? - ANSWER-
Endogenous
Why is sampling of wastewater important? - ANSWER-Evaluate the wastewater
treatment process
What is the purpose of the Biochemical Oxygen Demand Test? - ANSWER-
Measures the amount of oxygen used by microorganisms
The type of pump that is most common in a wastewater treatment facility is a? -
ANSWER-Centrifugal
What does NPDES stand for? - ANSWER-National Pollutant Discharge
Elimination System
,Head is a measure of pressure always expressed in? - ANSWER-Feet
A mixture of activated sludge and wastewater is called? - ANSWER-Mixed liquor
Which test measures the solids in and out of the treatment process for plant
efficiency? - ANSWER-Total suspended solids test
Complete mix, step aeration, and contact stabilization are modifications of what
process? - ANSWER-Activated sludge
One horsepower is equal to lifting? - ANSWER-33,000 pounds one foot in one
minute
Municipal wastewater consists of approximately what percentage of water? -
ANSWER-99.9%
Sewers that convey both sanitary wastes and storm waters are called? - ANSWER-
Combined sewers
The component in the aeration system that breaks up the air bubbles is known as
the? - ANSWER-Diffuser
As the temperature ????? Microorganisms accelerate consumption of Organics -
ANSWER-Increases
Grab samples taken in sizes that correspond to the flow rate are known as? -
ANSWER-Flow proportional
,One electrical horsepower is equal to? - ANSWER-0.746 kilowatts
Disease causing organisms are called? - ANSWER-Pathogens
MSDS stands for? - ANSWER-Material Safety Data Sheet
Sludge retention time (SRT) in a conventional activated sludge system should be? -
ANSWER-5-15 days
Anaerobic decomposition of wastewater produces? - ANSWER-Hydrogen sulfide
Three controls for activated sludge operation are? - ANSWER-Number of
microorganisms, D.O. And treatment time
An operator monitors the treatment process for parameters found in the? -
ANSWER-NPDES permit
Which is not the objective of a pretreatment program? - ANSWER-Allowing
industrial waste to be hauled from the treatment site
A test that provides the relative measure of the amount of food available to the
biological system, the degree of stabilization of the wastewater, and the effect of
the effluent on the receiving stream is called? - ANSWER-Biochemical oxygen
demand
Two of the most commonly used methods of supplying air to the wastewater
treatment process are? - ANSWER-Mechanical and diffused aeration
, The 30-minute settling data, when combined with the mixed liquor suspended
solids data, can be used to calculate the parameter called? - ANSWER-Sludge
volume index test
Raw wastewater typically has a pH near? - ANSWER-7
What percent organic matter would you expect domestic wastewater to be? -
ANSWER-75%
Disinfection of WWTP effluent ???? Or ????? Pathogenic bacteria, viruses, and
amoebic cysts commonly found in wastewater. - ANSWER-Inactivates or destroys
Liquid waste collected from residential, commercial, and industrial areas and
conveyed to a central location is generally called? - ANSWER-Wastewater
MCRT is used to indicate when activated sludge should be? - ANSWER-Wasted
The mixture of wastewater and returned activated sludge in the aeration tank of an
activated sludge system is called? - ANSWER-Mixed liquor
Low solids in the return sludge could be an indication of? - ANSWER-Excessive
wasting
What is the typical range for influential BOD5? - ANSWER-100-259mg/l
The centrifugal pump has how many moving parts? - ANSWER-One
EXAM 350 QUESTIONS & CORRECT ANSWERS
LATEST 2026/2027
In the formula Q=V(A), Q is defined as rate of flow expressed as? - ANSWER-Cu.
Ft. / sec.
What is the primary objective of the Clean Water Act of 1972? - ANSWER-
Restore and maintain the chemical, physical, and biological integrity of water in
the US
When cells use their own protoplasm and start to eat each other, as food to provide
the energy to maintain life, this is known as what type of growth? - ANSWER-
Endogenous
Why is sampling of wastewater important? - ANSWER-Evaluate the wastewater
treatment process
What is the purpose of the Biochemical Oxygen Demand Test? - ANSWER-
Measures the amount of oxygen used by microorganisms
The type of pump that is most common in a wastewater treatment facility is a? -
ANSWER-Centrifugal
What does NPDES stand for? - ANSWER-National Pollutant Discharge
Elimination System
,Head is a measure of pressure always expressed in? - ANSWER-Feet
A mixture of activated sludge and wastewater is called? - ANSWER-Mixed liquor
Which test measures the solids in and out of the treatment process for plant
efficiency? - ANSWER-Total suspended solids test
Complete mix, step aeration, and contact stabilization are modifications of what
process? - ANSWER-Activated sludge
One horsepower is equal to lifting? - ANSWER-33,000 pounds one foot in one
minute
Municipal wastewater consists of approximately what percentage of water? -
ANSWER-99.9%
Sewers that convey both sanitary wastes and storm waters are called? - ANSWER-
Combined sewers
The component in the aeration system that breaks up the air bubbles is known as
the? - ANSWER-Diffuser
As the temperature ????? Microorganisms accelerate consumption of Organics -
ANSWER-Increases
Grab samples taken in sizes that correspond to the flow rate are known as? -
ANSWER-Flow proportional
,One electrical horsepower is equal to? - ANSWER-0.746 kilowatts
Disease causing organisms are called? - ANSWER-Pathogens
MSDS stands for? - ANSWER-Material Safety Data Sheet
Sludge retention time (SRT) in a conventional activated sludge system should be? -
ANSWER-5-15 days
Anaerobic decomposition of wastewater produces? - ANSWER-Hydrogen sulfide
Three controls for activated sludge operation are? - ANSWER-Number of
microorganisms, D.O. And treatment time
An operator monitors the treatment process for parameters found in the? -
ANSWER-NPDES permit
Which is not the objective of a pretreatment program? - ANSWER-Allowing
industrial waste to be hauled from the treatment site
A test that provides the relative measure of the amount of food available to the
biological system, the degree of stabilization of the wastewater, and the effect of
the effluent on the receiving stream is called? - ANSWER-Biochemical oxygen
demand
Two of the most commonly used methods of supplying air to the wastewater
treatment process are? - ANSWER-Mechanical and diffused aeration
, The 30-minute settling data, when combined with the mixed liquor suspended
solids data, can be used to calculate the parameter called? - ANSWER-Sludge
volume index test
Raw wastewater typically has a pH near? - ANSWER-7
What percent organic matter would you expect domestic wastewater to be? -
ANSWER-75%
Disinfection of WWTP effluent ???? Or ????? Pathogenic bacteria, viruses, and
amoebic cysts commonly found in wastewater. - ANSWER-Inactivates or destroys
Liquid waste collected from residential, commercial, and industrial areas and
conveyed to a central location is generally called? - ANSWER-Wastewater
MCRT is used to indicate when activated sludge should be? - ANSWER-Wasted
The mixture of wastewater and returned activated sludge in the aeration tank of an
activated sludge system is called? - ANSWER-Mixed liquor
Low solids in the return sludge could be an indication of? - ANSWER-Excessive
wasting
What is the typical range for influential BOD5? - ANSWER-100-259mg/l
The centrifugal pump has how many moving parts? - ANSWER-One
