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TEXAS WASTEWATER CLASS B
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WASTEWATER TREATMENT OPERATOR CERTIFICATION EXAM
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TEXAS WASTEWATER CLASS B
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TEXAS WASTEWATER CLASS B NEWEST ACTUAL EXAMIf 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
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
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 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
-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
-maintaining dissolved oxygen in the wastewater
-minimizing hydraulic detention times in pipes and wet wells
-routinely and frequently disposing of screenings and grit
How does chlorine control odors? - ANSWER: -destroys bacteria that convert sulfate
to sulfide
-destroys hydrogen sulfide at the point of application
-inhibits the growth of slime layers in sewers
How does hydrogen peroxide control odors? - ANSWER: -by killing sulfate-reducing
bacteria
-by oxidant action
-by producing oxygen
What are the advantages of using hydrogen peroxide to control odors? - ANSWER: -
ability to inhibit the regeneration of sulfate-reducing microorganisms
-effectiveness as an oxidant
-lack of toxic by-products
Which odorous gases can be removed by absorption by a hypochlorite process? -
ANSWER: -ammonia
-hydrogen sulfide
-mercaptans
-organic gases
-sulfur dioxide
To ensure optimal odor removal efficiency of a chemical mist odor control system,
which tasks should be performed daily? - ANSWER: -check chemical feed pumps
-check chemical tank levels
-check outlet hydrogen sulfide concentration
-check water flow rate and pressure
, Which safety precautions should be taken when working with or installing a chemical
mist odor control system? - ANSWER: -provide an emergency eye wash/deluge
shower in an easily accessible location near the installation
-provide secondary containment for the chemical storage tanks
-routinely inspect the system for leaks
-use proper lockout/blockout procedures when working on equipment
-wear PPE when handling process chemicals
What are the advantages of using activated carbon adsorption to control odors? -
ANSWER: -ability to increase adsorbent capability by the use of additive compounds
-accommodation of high gas flow rates by the use of multiple units
-fairly consistent reliability
-simple operation
Which safety precautions should be taken when working with or installing activated
carbon odor control units? - ANSWER: -adequately ground carbon treatment systems
-implement engineering controls to eliminate dust inhalation
-make available in the work area an emergency eye wash/deluge shower and
washing facilities
-prevent contact between carbon and strong oxidizing agents
-use approved confined space procedures for vessel entry
What are possible solutions to odor problems in the primary sedimentation area of a
wastewater treatment plant? - ANSWER: -air stream treatment
-chemical addition
-chemical addition at headworks
-cover tanks, vent odors, and treat
-remove sludge faster
Equipment and instruments must be available in enclosed spaces to detect what
kinds of conditions? - ANSWER: -explosive conditions
-hydrogen sulfide
-oxygen concentration
The pure oxygen activated sludge system is a modification of the air activated sludge
process.
T or F - ANSWER: true
The PSA Oxygen Generating Systems are usually installed in larger plants.
T or F - ANSWER: false- usually in smaller plants
All types of hydrocarbon and other flammable materials may be allowed to mix with
oxygen.
T or F - ANSWER: false
To operate the activated sludge process efficiently, a properly settling mixed liquor
must be achieved and maintained.
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