CLASS B WASTEWATER
CLASS B WASTEWATER EXAM QUESTIONS AND ANSWERS WELL
ILLUSTRATED.
If wastewater contains dissolved oxygen, the biological breakdown will reduce
sulfate to sulfide.
T or F answer > False
At a pH below 5, all sulfide is present in the gaseous h2s form and most of it can
be released from wastewater.
T or F answer > True
In order to control odors effectively, the operator should know where odors
originate and the cause.
T or F answer > True
Chlorination is one of the oldest and least effective methods of controlling odors.
T or F answer > False- it is one of the oldest & most effective
The reaction of chlorine with certain chemicals can cause a more odorous gas.
T or F answer > True
Decreasing the pH of wastewater is an effective odor control method for
hydrogen sulfide.
T or F answer > False- Increasing is an effective method
,CLASS B WASTEWATER
Odor control towers must have a biomass established on the filter media in order
to remove odors.
T or F answer > True
The hazard classification of the spent carbon from odor control must be
established when considering disposal.
T or F answer > True
Regeneration of activated carbon temporarily eliminates any concerns about
hazardous waste disposal.
T or F answer > True
Hydrogen sulfide gas combines with moisture to form sulfuric acid, which is very
corrosive.
T or F answer > True
Which factor causes increased odor and corrosion problems in wastewater
treatment plants? answer > Increased travel times for wastewater to reach
treatment plants
What is the principle source of odor generation in wastewater collection systems
and treatment processes? answer > Production of inorganic and organic gases by
microorganisms
What is the main cause of most odors in wastewater systems? answer >
Hydrogen sulfide
,CLASS B WASTEWATER
What is the most common source of sulfide in wastewater? answer > Biological
activity in the collection sewer or treatment plant
Why is the temperature of the wastewater system an important factor in the
production of hydrogen sulfide gas? answer > The rate of bacterial metabolism is
related to temperature
Why does ozone have limited use in controlling odors? answer > Because an
effective concentration may be too costly to use at large treatment plants
What is the problem with using combustion to remove odors from wastewater
treatment plant gases? answer > The combustibility of the gases is so low that
fuel costs are high
How can cathode scale be removed from an electrolytic chemical scrubber unit?
answer > Flush the system with dilute nitric acid
What is the adsorption odor removal process? The process in which odorous
components are removed from a gas through answer > Adherence to a solid
surface
What is the best solution to odor problems? answer > Prevent odors from ever
developing
How are odors generated in wastewater collection systems and treatment plants?
answer > -Biological generation
-Hydrogen sulfide generation
, CLASS B WASTEWATER
-Hydrogen transfer schemes
Which problems are created by hydrogen sulfide gas? answer > -corrosion or
deterioration of concrete sewer structures
-explosive gas mixtures
-hazards to the respiratory system to persons working in confined or close spaces
-rotten egg odor
Which items are facts that can help in odor classification? answer > -individuals
respond differently to the same odor
-odors travel great distances with the direction of the wind
-small concentrations of odors can be offensive
-some odors are objectionable and others are pleasant
-the human nose rapidly becomes fatigued (insensitive) to odors
Investigations in the neighborhood near the location of an odor complaint may
reveal that the odors are coming from which possible nearby sources? answer > -
dead animal
-home plumbing problem
-sewer
-storm drain
-trash pile
Which items are possible solutions operators can use to control odors? answer >
-changing or enforcing sewer-use ordinances
-immediately removing floating scum/solids
CLASS B WASTEWATER EXAM QUESTIONS AND ANSWERS WELL
ILLUSTRATED.
If wastewater contains dissolved oxygen, the biological breakdown will reduce
sulfate to sulfide.
T or F answer > False
At a pH below 5, all sulfide is present in the gaseous h2s form and most of it can
be released from wastewater.
T or F answer > True
In order to control odors effectively, the operator should know where odors
originate and the cause.
T or F answer > True
Chlorination is one of the oldest and least effective methods of controlling odors.
T or F answer > False- it is one of the oldest & most effective
The reaction of chlorine with certain chemicals can cause a more odorous gas.
T or F answer > True
Decreasing the pH of wastewater is an effective odor control method for
hydrogen sulfide.
T or F answer > False- Increasing is an effective method
,CLASS B WASTEWATER
Odor control towers must have a biomass established on the filter media in order
to remove odors.
T or F answer > True
The hazard classification of the spent carbon from odor control must be
established when considering disposal.
T or F answer > True
Regeneration of activated carbon temporarily eliminates any concerns about
hazardous waste disposal.
T or F answer > True
Hydrogen sulfide gas combines with moisture to form sulfuric acid, which is very
corrosive.
T or F answer > True
Which factor causes increased odor and corrosion problems in wastewater
treatment plants? answer > Increased travel times for wastewater to reach
treatment plants
What is the principle source of odor generation in wastewater collection systems
and treatment processes? answer > Production of inorganic and organic gases by
microorganisms
What is the main cause of most odors in wastewater systems? answer >
Hydrogen sulfide
,CLASS B WASTEWATER
What is the most common source of sulfide in wastewater? answer > Biological
activity in the collection sewer or treatment plant
Why is the temperature of the wastewater system an important factor in the
production of hydrogen sulfide gas? answer > The rate of bacterial metabolism is
related to temperature
Why does ozone have limited use in controlling odors? answer > Because an
effective concentration may be too costly to use at large treatment plants
What is the problem with using combustion to remove odors from wastewater
treatment plant gases? answer > The combustibility of the gases is so low that
fuel costs are high
How can cathode scale be removed from an electrolytic chemical scrubber unit?
answer > Flush the system with dilute nitric acid
What is the adsorption odor removal process? The process in which odorous
components are removed from a gas through answer > Adherence to a solid
surface
What is the best solution to odor problems? answer > Prevent odors from ever
developing
How are odors generated in wastewater collection systems and treatment plants?
answer > -Biological generation
-Hydrogen sulfide generation
, CLASS B WASTEWATER
-Hydrogen transfer schemes
Which problems are created by hydrogen sulfide gas? answer > -corrosion or
deterioration of concrete sewer structures
-explosive gas mixtures
-hazards to the respiratory system to persons working in confined or close spaces
-rotten egg odor
Which items are facts that can help in odor classification? answer > -individuals
respond differently to the same odor
-odors travel great distances with the direction of the wind
-small concentrations of odors can be offensive
-some odors are objectionable and others are pleasant
-the human nose rapidly becomes fatigued (insensitive) to odors
Investigations in the neighborhood near the location of an odor complaint may
reveal that the odors are coming from which possible nearby sources? answer > -
dead animal
-home plumbing problem
-sewer
-storm drain
-trash pile
Which items are possible solutions operators can use to control odors? answer >
-changing or enforcing sewer-use ordinances
-immediately removing floating scum/solids
