Disinfection

Question 1

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

Answer 1

True

Question 2

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

Answer 2

False. At lower temperatures.

Question 3

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

Answer 3

True

Question 4

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

Answer 4

False

Question 5

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

Answer 5

True

Question 6

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

Answer 6

True

Question 7

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

Answer 7

False

Question 8

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

Answer 8

True

Question 9

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

Answer 9

True

Question 10

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

Answer 10

True

Question 11

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

Answer 11

Routed to a treatment system

Question 12

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

Answer 12

Taste and Odors

Question 13

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

Answer 13

Repeat disinfection

Question 14

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

Answer 14

Chlorine is a hazardous chemical

Question 15

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

Answer 15

Chlorine dose

Question 16

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.

Answer 16

Prevent mains from becoming contaminated during construction and repair

Question 17

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.

Answer 17

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

Question 18

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

Answer 18

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

Question 19

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

Answer 19

Chloramines are less effective as a disinfectant than free chlorine residuals

Question 20

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

Answer 20

Breakpoint

Question 21

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

Answer 21

To destroy harmful organisms

Question 22

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

Answer 22

Corrosion problems

Question 23

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

Answer 23

organisms capable of causing diseases

Question 24

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

Answer 24

equipment that feeds liquid chlorine solutions

Question 25

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

Answer 25

During storms and the snow melt season

Question 26

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

Answer 26

1. Concurrent addition of chlorine and ammonia 4. Preammoniation followed by chlorination 5. Prechlorination/ postammoniation

Question 27

Which items are physical means of disinfection? 1. Bases 2. Heat 3. Ozone 4. Ultrasonic waves 5. Ultrasonic rays

Answer 27

2. Heat 4. Ultrasonic waves 5. Ultraviolet rays

Question 28

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.

Answer 28

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

Question 29

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.

Answer 29

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

Question 30

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.

Answer 30

2. Atmospheric monitoring devices 3. Chlorine leak detection equipment 5. Self-contained breathing apparatus

Question 31

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.

Answer 31

1. ferrous ion 2. hydrogen sulfide 3. manganous ion 5. nitrite ion

Question 32

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.

Answer 32

1. aid coagulation 2. control algal problems in basins 4. provide sufficient chlorine contact time to effectively kill or inactivate pathogenic organisms 5. reduce odor problems in treated water

Question 33

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.

Answer 33

1. chloramine concentration used 2. detention time in the reservoir or distribution system 3. excess ammonia in the water system 5. water temperature

Question 34

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.

Answer 34

1. After construction 3. After maintenance 4. After repairs

Question 35

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.

Answer 35

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

Question 36

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.

Answer 36

1. Calculate the chlorine usage 2. Check the chlorine residual 3. Inspect auxiliary equipment 5. Record the rotameter reading and time

Question 37

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

Answer 37

1. Ability of the treatment plant to meet various regulations 2. Distribution system characteristics 4. Operational practices 5. Quality of the raw water

Question 38

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

Answer 38

1. cross connections 2. main breaks 3. new main installations

Question 39

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

Answer 39

2. Bacteria 4. Internal parasites 5. Viruses

Question 40

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

Answer 40

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

Question 41

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

Answer 41

1. can consume great amounts of disinfectants | 2. can form unwanted compounds, including THMs

Question 42

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

Answer 42

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 and dewatered

Question 43

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

Answer 43

1. Check for stoppages in the flow lines 2. Check the circuit breaker 4. Check the electrical connection

Question 44

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

Answer 44

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 4. Control of microorganisms that could produce slimes 5. Control of microorganisms that could produce tastes and odors

Question 45

Which items are parts of a chlorinator? 1. Check valve assembly 2. Diaphragm assembly 3. Interconnection manifold 4. Rate valve 5. The ejector

Answer 45

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