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Drinking Water Distribution > Disinfection > Flashcards

Disinfection Flashcards

1
Q

True or false? Using hypochlorite to treat potable water achieves the same result as using chlorine gas

A

True

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2
Q

True or false? Longer contact times are required to disinfect water at higher temperatures

A

False. At lower temperatures.

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3
Q

True or false? Combined chlorine residuals have poor disinfection power and may cause tastes and odors

A

True

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4
Q

True or false? The higher the turbidity (suspended solids, organic content, reducing agents) of the water, the better the disinfection

A

False

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5
Q

True or false? Clothing saturated with chlorine can irritate the person’s skin if exposed to moisture

A

True

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6
Q

True or false? Cysts and virus can be resistant to certain types of disinfectants

A

True

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7
Q

True or false? Once water from a well starts producing positive coliform test results, it is very easy to correct the problem with chlorine treatment

A

False

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8
Q

True or false? When organic material and calcium hypochlorite come in contact, the resulting chemical reactions can generate enough heat and oxygen to start and support a fire

A

True

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9
Q

True or false? The US Environmental Protection Agency sets federal drinking water regulations that all state and local agencies must enforce

A

True

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10
Q

True or false? The presence of coliform bacteria is an indication that water is polluted and may contain disease- causing organisms

A

True

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11
Q

When a chlorine leak occurs, what should be done with the ventilated air containing the chlorine?

a. Route the ventilated air back to the container
b. Route the ventilated air to a treatment system
c. Route the ventilated air to the atmosphere
d. Route the ventilated air to the product water

A

Routed to a treatment system

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12
Q

What is an undesirable effect of disinfectants in distribution system drinking water?

a. Decrease in corrosion
b. Formation of bio films
c. Increase in hardness
d. Tastes and odors

A

Taste and Odors

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13
Q

What should the operator do if bacteriological tests are unsatisfactory after disinfecting water mains?

a. Use another lab
b. Collect another sample
c. Repeat disinfection
d. Locate the source of contamination

A

Repeat disinfection

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14
Q

Why must chlorine be handled with care?

a. Chlorine is a hazardous chemical.
b. Chlorine is a scarce resource.
c. Chlorine is an expensive chemical
d. Chlorine is a water disinfectant

A

Chlorine is a hazardous chemical

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15
Q

What is the term for the amount of chlorine added to water to disinfect it?

a. Chlorine breakpoint
b. Chlorine demand
c. Chlorine dose
d. Chlorine residual

A

Chlorine dose

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16
Q

What is the best preventive measure to help simplify the disinfection of water mains?

a. Apply disinfecting chemicals continuously.
b. Prevent mains from becoming contaminated during construction and repair
c. Inspect water main manufacturers’ facilities
d. Use a flushing program.

A

Prevent mains from becoming contaminated during construction and repair

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17
Q

Why should every water utility agency have an ongoing chlorine safety training program for operators?

a. To introduce new operators to the program and update previously trained operators.
b. To keep safety staff current on safety regulations.
c. To meet legal and regulatory requirements.
d. To remind management of the importance of safety programs.

A

To introduce new operators to the program and update previously trained operators

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18
Q

What information should be given to the local fire department when planning ahead for chlorine emergency?

a. A clearly marked map indicating the location of the chlorine storage area, chlorinators, and emergency equipment.
b. A comprehensive list of nearby vegetation especially vulnerable of chlorine exposure.
c. Emergency phone numbers for the local media.
d. Training materials on how to locate and repair chlorine leaks

A

A clearly marked map indicating the location of the chlorine storage area, chlorinators, and emergency equipment

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19
Q

What is a major limitation of using chloramine residuals for disinfection?

a. Chloramines are less effective as a disinfectant than free chlorine residuals
b. Chloramines fail to maintain a detectable residual throughout the distribution system.
c. Chloramines increase taste and odors
d. Chloramines increase the formation of THM’s

A

Chloramines are less effective as a disinfectant than free chlorine residuals

20
Q

What is the term for the point in the disinfection process when enough chlorine has been added to the water to satisfy the chlorine demand?

a. Chloramines point
b. Free ammonia point
c. Breakpoint
d. Residual chlorine point

A

Breakpoint

21
Q

What is the purpose of the disinfection process?

a. To control corrosion
b. To destroy harmful organisms
c. To please consumers
d. To reduce taste and odors

A

To destroy harmful organisms

22
Q

What problems will occur if the chlorine injection point is located on the intake side of the pump?

a. Cavitation problems
b. Corrosion problems
c. Taste and odor problems
d. Water hammer problems

A

Corrosion problems

23
Q

What are pathogenic organisms?

a. Organisms capable of causing diseases
b. Organisms known to reproduce rapidly
c. Organisms that cause taste and odors
d. Organisms with the ability to degrade pollution

A

organisms capable of causing diseases

24
Q

What is a hypochlorinator?

a. Equipment that feeds chlorine solutions at a high rate
b. Equipment that feeds gaseous chlorine solution.
c. Equipment that feeds liquid chlorine solution
d. Equipment that feeds solid chlorine solution

A

equipment that feeds liquid chlorine solutions

25
Q

Under what conditions could the chlorine demand for surface water change continuously?

a. During a weekend sporting event
b. During peak water demand periods
c. During periods when operators are unavailable
d. During storms and the snow melt seasons

A

During storms and the snow melt season

26
Q

How are chloramines produced?

  1. Concurrent addition of chlorine and ammonia
  2. Breakpoint chlorination
  3. Nitrification/ denitrification
  4. Preammoniation followed by chlorination
  5. Perchlorination / postammoniation
A
  1. Concurrent addition of chlorine and ammonia
  2. Preammoniation followed by chlorination
  3. Prechlorination/ postammoniation
27
Q

Which items are physical means of disinfection?

  1. Bases
  2. Heat
  3. Ozone
  4. Ultrasonic waves
  5. Ultrasonic rays
A
  1. Heat
  2. Ultrasonic waves
  3. Ultraviolet rays
28
Q

If a chlorine spill or leak occurs, what first aid measures should be followed?

  1. Call 911 immediately and notify company safety personnel.
  2. If the victim is not breathing, place the person face up with the head and upper body in an upright position.
  3. If the victim is not breathing, being CPR.
  4. Keep the victim warm and clam.
  5. Leave the contaminated area.
A
  1. Call 911 immediately and notify company safety personnel
  2. If the victim is breathing, place the person face up with the head and upper body in an upright position
  3. If the victim is not breathing, begin cardiopulmonary respiration
  4. Keep the victim warm and calm
  5. Leave the contaminated area
29
Q

Which items should be included in all safety programs?

  1. A maintenance and calibration program for safety devices and equipment.
  2. Emergency procedures for chlorine leaks and first aid.
  3. Periodic hands-on training using safety equipment.
  4. Tours of facilities for police and fire departments to locate hazardous areas and provide chlorine safety information.
  5. Written rules and specific safety procedures.
A
  1. A maintenance and calibration program for safety devices and equipment
  2. Emergency procedures for chlorine leaks and first aid
  3. Periodic hands on training using safety equipment
  4. Tour of facilities for police and fire departments to locate hazardous areas and provide chlorine safety information
  5. Written rules and specific procedures
30
Q

What kinds of safety equipment require periodic hands-on training?

  1. Accident reports forms.
  2. Atmospheric monitoring devices.
  3. Chlorine leak-detection equipment.
  4. Chlorine residual measuring equipment.
  5. Self-contained breathing apparatus.
A
  1. Atmospheric monitoring devices
  2. Chlorine leak detection equipment
  3. Self-contained breathing apparatus
31
Q

Which items are examples of inorganic reducing agents that, if present in water, will react with chlorine?

  1. Ferrous ion.
  2. Hydrogen sulfide.
  3. Manganous ion.
  4. Nitrate ion.
  5. Nitrite ion.
A
  1. ferrous ion
  2. hydrogen sulfide
  3. manganous ion
  4. nitrite ion
32
Q

Why is sufficient chlorine added to raw water (perchlorination) to go past the breakpoint in plants where THMs are not a problem?

  1. To aid coagulation.
  2. To control algal problems in basins.
  3. To prevent the formation of THM’s.
  4. To provide sufficient chlorine contact time to effectively kill or inactivate pathogenic organisms.
  5. To reduce odor problems in treated water.
A
  1. aid coagulation
  2. control algal problems in basins
  3. provide sufficient chlorine contact time to effectively kill or inactivate pathogenic organisms
  4. reduce odor problems in treated water
33
Q

Which factors influence the nitrification process in water?

  1. Chloramine concentration used.
  2. Detention time in the reservoir or distribution system.
  3. Excess ammonia in the water system.
  4. Sample collection techniques.
  5. Water temperature.
A
  1. chloramine concentration used
  2. detention time in the reservoir or distribution system
  3. excess ammonia in the water system
  4. water temperature
34
Q

Under what conditions should a water storage tank be thoroughly cleaned before disinfecting the tank?

  1. After construction.
  2. After inspection.
  3. After maintenance.
  4. After repairs.
  5. After visits.
A
  1. After construction
  2. After maintenance
  3. After repairs
35
Q

Which tasks should be performed daily during normal operation of a hypochlorinator?

  1. Check the chemical feed pump operation.
  2. Check the chlorine residual in the system and adjust the chlorine feed rate as necessary.
  3. Inspect the building to make sure only authorized personnel have been there.
  4. Read and record the level of the hypochlorite solution tank at the same time.
  5. Read meters and record the amount of water pumped.
A
  1. Check the chemical feed pump operation
  2. Check the chlorine residual in the system and adjust the chlorine feed rate as necessary
  3. Inspect the building to make sure only authorized personnel have been there
  4. Read and record the level of the hypochlorite solution tank at the same time every day
  5. Read the meter and record the amount of water pumped
36
Q

Which daily routine observation and preventive maintenance tasks should be performed in the normal operation of a chlorinator?

  1. Calculate the chlorine usage.
  2. Check the chlorine residual.
  3. Inspect auxiliary equipment.
  4. Read the meter and record the number of gallons of water pumped.
  5. Record the rotameter reading and time.
A
  1. Calculate the chlorine usage
  2. Check the chlorine residual
  3. Inspect auxiliary equipment
  4. Record the rotameter reading and time
37
Q

Which factors influence an operator’s decision to use chloramines as an alternative disinfection?

  1. Ability of the treatment plant to meet various regulations.
  2. Distribution system characteristics.
  3. Form of chlorine available.
  4. Operational practices.
  5. Quality of the raw water
A
  1. Ability of the treatment plant to meet various regulations
  2. Distribution system characteristics
  3. Operational practices
  4. Quality of the raw water
38
Q

What are possible sources of contamination in water distribution systems?

  1. Cross-connection.
  2. Main breaks
  3. New main installation
  4. Sacrificial anodes
  5. Sequestering agents
A
  1. cross connections
  2. main breaks
  3. new main installations
39
Q

Which types of waterborne biological life forms may be pathogenic or disease-causing organisms?

  1. Amphibians
  2. Bacteria
  3. Fish
  4. Internal parasites
  5. Viruses
A
  1. Bacteria
  2. Internal parasites
  3. Viruses
40
Q

Which strategies can be used for preventing and controlling nitrification?

  1. Chlorinate to the breakpoint
  2. Decrease detention times
  3. Decrease free ammonia
  4. Establish a flushing program
  5. Increase the disinfection dosage ratio
A
  1. Chlorinate to the breakpoint
  2. Decrease detention times
  3. Decrease free ammonia
  4. Establish a flushing program
  5. Increase the disinfection dosage ratio
41
Q

Why is organic matter undesirable in water being disinfected?

  1. Can consume great amounts of disinfectants
  2. Can form unwanted compounds, including THMs
  3. Can form precipitates
  4. Can provide nutrients for pathogens
  5. Can provide substrate (food) for pathogens
A
  1. can consume great amounts of disinfectants

2. can form unwanted compounds, including THMs

42
Q

What measures can be used to prevent water mains from becoming contaminated?

  1. Implement and maintain a good recordkeeping system
  2. Inspect the interior of all pipes for cleanliness as the main is laid in the trench
  3. Install watertight plugs in all open-end joints whenever the trench is unattended for any length of time
  4. Keep outside material out of mains being installed or repaired
  5. Keep the trenches dry or dewatered
A
  1. Inspect the interior of all pipes for cleanliness as the main is laid in the trench
  2. Install watertight plugs in all open-end joints whenever the trench is unattended for any length of time
  3. Keep outside material out of mains being installed or repaired
  4. Keep the trenches dry and dewatered
43
Q

Which items should be checked when troubleshooting a hypochlorinator pump that is not operating?

  1. Check for stoppages in the flow lines
  2. Check the circuit breaker
  3. Check the date of the last visit by regulators
  4. Check the electrical connection
  5. Check the supply records
A
  1. Check for stoppages in the flow lines
  2. Check the circuit breaker
  3. Check the electrical connection
44
Q

What are the benefits of maintaining a chlorine residual throughout the distribution system?

  1. Biological control and elimination of coliform bacteria that might reach water in the distribution system through cross connections
  2. Biological control and elimination of coliform bacteria that might reach water in the distribution system through leakage into the system
  3. Control of corrosion
  4. Control of microorganisms that could produce slimes
  5. Control of microorganisms that could produce tastes and odors
A
  1. Biological control and elimination of coliform bacteria that might reach water in the distribution system through cross connections
  2. Biological control and elimination of coliform bacteria that might reach water in the distribution system through leakage into the system
  3. Control of microorganisms that could produce slimes
  4. Control of microorganisms that could produce tastes and odors
45
Q

Which items are parts of a chlorinator?

  1. Check valve assembly
  2. Diaphragm assembly
  3. Interconnection manifold
  4. Rate valve
  5. The ejector
A
  1. Check valve assembly
  2. Diaphragm assembly
  3. Interconnection manifold
  4. Rate valve
  5. The ejector

Drinking Water Distribution (9 decks)

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