Water Treatment

Question 1

Two important steps in the hydrologic cycle are precipitation and run-off. Name two others.
A. Condensation, percolation
B. Evaporation, respiration
C. Percolation, expiration
D. Transformation, reservation

Answer 1

A. Condensation, percolation

Question 2

Water put into the atmosphere by living plants is known as:
A. Condensation
B. Transformation
C. Transpiration
D. Sedimentation

Answer 2

C. Transpiration

Question 3

Name the basic types of groundwater sources.
A. Dug wells, drilled wells, vertical turbines
B. Shallow wells, deep wells, springs
C. Driven wells, regenerative turbine, jet pump
D. Pneumatic, artesian, submersible

Answer 3

B. Shallow wells, deep wells, springs

Question 4

Which of the following tends to decrease per capita water consumption?
A. High water pressure
B. Availability of a sewer system
C. Metered water
D. Lower cost of water

Answer 4

C. Metered water

Question 5

Of the following, which two months of the year tend to have the highest water usage?
A. October, November
B. December, January
C. March, April
D. July, August

Answer 5

D. July, August

Question 6

Water consumption is usually lowest at about ____ and highest at about _____.
A. 0700h; 1500h
B. 0900h; 2300h
C. 1100h; 2100h
D. 0300h; 1900h

Answer 6

D. 0300h; 1900h

Question 7

Groundwater usually:
A. Is very turbid
B. Is highly polluted
C. Has higher concentrations of dissolved minerals
D. Does not require softening

Answer 7

C. Has higher concentrations of dissolved minerals

Question 8

Name three factors that must be considered when designing a distribution system.
A. Demand, topography, layout
B. Demand, manhole locations, topography
C. Topography, climate, receiving stream
D. Topography, manhole locations, infiltration

Answer 8

A. Demand, topography, layout

Question 9

Which of the following is true?
A. A minimum horizontal distance between a private well and a septic tank is 10m.
B. If wells are close together, they interact with each other to increase the available yield of each well.
C. Water divining (“witching”) is a good way to locate a new well.
D. Old wells can be reclaimed with purification techniques.

Answer 9

A. A minimum horizontal distance between a private well and a septic tank is 10m

Question 10

List three advantages of groundwater as compared to surface water.
A. Uniform temperature, uniform quality, water is clarified.
B. Uniform temperature, more available, usually more dissolved salts.
C. Usually cheaper, usually less contaminated, uniform temperature.
D. Usually cheaper, uniform quality, iron and manganese problems.

Answer 10

C. Usually cheaper, usually less contaminated, uniform temperature.

Question 11

Which of the following lists the three basic types of wells?
A. Dug, vertical turbine, pneumatic
B. Dug, driven, drilled
C. Submersible, jet pump, drilled
D. Drilled, artesian, centrifugal

Answer 11

B. Dug, driven, drilled

Question 12

Why are gravel packs used in wells?
A. To absorb spills.
B. To remove iron and manganese.
C. To provide a source of cavitation.
D. To increase the flow of available water.

Answer 12

D. To increase the flow of available water.

Question 13

What is the purpose of a screen in a well?
A. To prevent sand from entering the well.
B. To remove algae.
C. To remove iron and manganese.
D To absorb spills.

Answer 13

A. To prevent sand from entering the well.

Question 14

What is the main factor which influences the size of well screen openings?
A. Cost
B. The supplier
C. The type of device used to cut the openings
D. Particle size of the surrounding material

Answer 14

D. Particle size of the surrounding material

Question 15

What are three types of valves commonly used in well systems?
A. Pressure sustaining, ball check, blowdown
B. Check, diaphragm, rotameter
C. Flow control, blow down, needle
D. Surge control, air/vacuum release, flow control

Answer 15

D. Surge control, air/vacuum release, flow control

Question 16

What are the three most common causes of poor well performance?
A. Sand intrusion, under pumping, high water table
B. Over pumping, corrosion, cracked well slab
C. Over pumping, sand intrusion, corrosion and encrustations
D. Scale formation, under pumping, operator error

Answer 16

C. Over pumping, sand intrusion, corrosion and encrustations

Question 17

What are four methods commonly used to increase the efficiency and yield of a well?
A. Jetting, acid treatment, chlorine, surging
B. Use of polyphosphates, over pumping, install a check valve
C. Acid treatment, over pumping, abandonment, chlorine
D. Surging, prolonged discontinued use, recalibration, jetting

Answer 17

A. Jetting, acid treatment, chlorine, surging

Question 18

The main purpose of filtration is to:
A. Remove solid particles from the water.
B. Reduce tastes and odours.
C. Provide good mixing for chlorine.
D. Remove iron and manganese.

Answer 18

A. Remove solid particles from the water.

Question 19

What are the criteria which should be used to determine when a filter needs to be backwashed?
A. Head loss, pump availability, sampling frequency
B. Filter effluent turbidity, length of run, degree of media clogging
C. Head loss, regulatory inspection, flow
D. Filter effluent turbidity, day of the week, head gain

Answer 19

B. Filter effluent turbidity, length of run, degree of media clogging

Question 20

What causes the head loss through a filter to increase?
A. Accumulation of solids in the bed
B. Loss of filter media from backwashing
C. Decrease of loading rate
D. Plant shutdown

Answer 20

A. Accumulation of solids in the bed

Question 21

Two types of filters commonly used in the water treatment industry are:
A. Greensand and ISI
B. Rapid gravity and pressure
C. Activated carbon and culligan
D. Slow sand and up flow

Answer 21

B. Rapid gravity and pressure

Question 22

Why is backwashing of a filter necessary?
A. To ensure that the backwash pumps are functioning properly.
B. To recycle treated water.
C. To remove accumulated solids from the bed.
D. To prevent THM formation.

Answer 22

C. To remove accumulated solids from the bed.

Question 23

Which one of the choices best describes what occurs during a filter backwash?
A. Raw water passes through the filter, removing accumulated debris and material.
B. The filter media is disinfected and replaced when necessary.
C. Media begins to block off causing short circuiting and eventually cracking, leading to breakthrough.
D. Flow is reversed through the filter; accumulated solids are removed and are carried out as backwash waste water for disposal.

Answer 23

D. Flow is reversed through the filter; accumulated solids are removed and are carried out as backwash waste water for disposal.

Question 24

Why is there sometimes more than one layer of media in a filter?
A. Media often needs to be topped off and the original material may no longer be available.
B. A second bed of lighter, coarser material removes larger particles first allowing longer runs and good effluent quality.
C. Media uniformity coefficients are beyond normal specifications.
D. To compensate for insufficient filter surface area.

Answer 24

B. A second bed of lighter, coarser material removes larger particles first allowing longer runs and good effluent quality.

Question 25

Of the following, what is the best single measurement to determine how efficiently a filter is operating? A. Free chlorine residual B. Clearwell clarity C. Filter effluent turbidity D. Bacteriological testing

Answer 25

C. Filter effluent turbidity

Question 26

The two most common types of filters used for iron and manganese control in small to medium size water treatment plants are: A. Pyrolusite, anthracite B. Zeolite, biological C. Slow sand, up flow D. Greensand, pyrolusite

Answer 26

D. Greensand, pyrolusite

Question 27

Pressure filters are often used in small plants because: A. They are compact, and therefore occupy very little room. B. They can be operated at lower loading rates than rapid gravity filters. C. Automatic control systems cannot be easily installed. D. They are available as a "package", which usually results in lower maintenance costs.

Answer 27

A. They are compact, and therefore occupy very little room.

Question 28

Iron and manganese concentrations in water can be reduced by oxidation. This can be achieved by aeration, by chlorination, or by the use of other chemicals such as potassium permanganate. What happens to the iron and manganese which was dissolved in the water when these methods are used? A. It is released to the air in the form of a gas. B. It changes from a soluble state to an insoluble state and solid particles are formed. C. Iron and manganese combine to form a harmless compound. D. Iron and manganese combine with anions to form dissolved compounds.

Answer 28

B. It changes from a soluble state to an insoluble state and solid particles are formed.

Question 29

Which of the following are possible sources of bad taste or odours in drinking water? A. Algae, low temperature B. Decomposing organic matter, low turbidity C. Dissolved gases, microorganisms D. Urban runoff, inadequate combined chlorine residual

Answer 29

C. Dissolved gases, microorganisms

Question 30

Why does the use of copper sulfate for algae control sometimes increase taste and odour problems? A. If CuS04 is applied too late, the dead algae and decomposing material will cause taste and odor problems. B. If too much is used it reacts with dissolved gases to cause taste and odor problems. C. It replaces the dissolved oxygen present and will cause taste and odor problems. D. If applied incorrectly it will cause a floc to form in the reservoir.

Answer 30

A. If CuS04 is applied too late, the dead algae and decomposing material will cause taste and odor problems.

Question 31

How does aeration help remove taste and odour producing compounds? A. Aeration increases dissolved oxygen; thereby decreasing corrosiveness of the water. B. It oxidizes some compounds to insoluble forms and removes volatiles by degasification. C. It decreases the pH, preventing odour, and promoting microorganism proliferation. D. pH is increased, thereby increasing alkalinity.

Answer 31

B. It oxidizes some compounds to insoluble forms and removes volatiles by degasification.

Question 32

Which two chemicals are commonly used for oxidation of taste and odour producing compounds in drinking water? A. Aluminum sulfate or chlorine. B. Sodium silicate or potassium permanganate. C. Polyphosphate or sodium hydroxide. D. Potassium permanganate or chlorine.

Answer 32

D. Potassium permanganate or chlorine.

Question 33

What are two of the common sources of chlorine used in drinking water disinfection? A. Chlorine gas, sodium hypochlorite B. Potassium permanganate, calcium hypochlorite C. Chlorophenols, HTH D. Calcium hydroxide, sodium silicate

Answer 33

A. Chlorine gas, sodium hypochlorite

Question 34

What are chloramines? A. Carcinogenic by-products of disinfection. B. Free chlorine residual. C. Ammonia that has been reduced by microorganism activity. D. Compounds of chlorine and ammonia.

Answer 34

D. Compounds of chlorine and ammonia.

Question 35

What is chlorine demand? A. The chlorine necessary to attain a required residual. B. Chlorine required to be on hand to use for emergency disinfection. C. Chlorine used up by reducing compounds before a residual is formed. D. The dosage necessary to maintain breakpoint.

Answer 35

C. Chlorine used up by reducing compounds before a residual is formed.

Question 36

Calculate the daily mass of chlorine gas required to apply a dosage of 2.0 mg/L of chlorine to a water flow of 3000 L/min. A. 8 640 g/day B. 6 000 g/day C. 15 000 g/day D. 360 000 g/day

Answer 36

A. 8 640 g/day

Question 37

What is the health rationale for fluoridation? A. To prevent mottling of teeth. B. To reduce the incidence of tooth decay in children. C. To fulfill plebiscite and bylaw requirements. D. To minimize giardia outbreaks.

Answer 37

B. To reduce the incidence of tooth decay in children.

Question 38

Calculate the daily volume of sodium hypochlorite (15 g/L available chlorine) required to apply the same chlorine dosage as in Question 38. A. 400 L/day B. 130 L/day C. 1296 L/day D. 576 L/day

Answer 38

D. 576 L/day

Question 39

What is the effect on the human body of exposure to fluoride at five mg/L in drinking water over an extended time? A. A calcium imbalance may occur B. Teeth may become mottled (discoloured). C. Increased blood pressure. D. A rash may develop.

Answer 39

B. Teeth may become mottled (discoloured).

Question 40

Which of the following are basic methods of sampling water? A. Grab and composite. B. Bacteriological and chemical. C. Mandatory and voluntary. D. Preserved and non-preserved.

Answer 40

A. Grab and composite.

Question 41

Which one of the following is a list of laboratory tests commonly done in Class I water treatment plants? A. Fluoride, BOD5, conductivity, corrosion index. B. Manganese, MLSS, chlorine residual, pH. C. pH, iron, chlorine residual, turbidity. D. Solids settleability, volatile solids, heavy metals, cryptosporidium.

Answer 41

C. pH, iron, chlorine residual, turbidity.

Question 42

Which treatment method is paired with an incorrect injection point? A. Chlorine gas; Pre-sedimentation B. Chlorine dioxide solution; Post-sedimentation C. Ozone; Pre-filtration D. Ultraviolet; Post-filter

Answer 42

A. Chlorine gas; Pre-sedimentation

Question 43

Formation of trihalomethanes during pre-treatment disinfection is attributed to the use of? A. Chlorine dioxide B. Chlorine C. Ozone D. UV disinfection

Answer 43

B. Chlorine

Question 44

Long-term over-fluoridation of a water supply could lead to: A. No noticeable effect. B. Mottling of teeth in children. C. Softening of tooth enamel and cavity formation in children. D. Trihalomethane formation.

Answer 44

B. Mottling of teeth in children.

Question 45

Disinfection effectiveness is impacted by chlorine residual, pH, temperature, and turbidity. Which of the following statements is false? A. As pH increases, disinfection effectiveness increases. B. As temperature increases, disinfection effectiveness increases. C. As turbidity increases, disinfection effectiveness decreases. D. As chlorine dosage increases, disinfection effectiveness increases.

Answer 45

A. As pH increases, disinfection effectiveness increases.

Question 46

Which process is not used to remove inorganic contaminants from raw water? A. Coagulation B. Aeration C. Ion Exchange D. Ozonation

Answer 46

D. Ozonation