Water Treatment Operations Guidelines Flashcards by Matthew Fritz

Backwash water is which percentage of the total filtered water in a conventional rapid sand filter system?
a. 1%
b. 2 to 4%
c. 5 to 6%
d. 6 to 10%

b. 2 to 4%

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The sample bottle should be filled to _____ when collecting a bacteriological sample.
a. halfway or more
b. within 1 inch of the top
c. overflowing
d. the top

b. within 1 inch from the top

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When using chlorine as a disinfecting agent, there are several factors that affect the disinfection process. The disinfection process tends to work better:
a. when pH is lower and water temp is lower
b. when pH is lower and water temp is higher
c. when pH is higher and water temp is lower
d. when pH is higher and water temp is higher

b. when pH is lower and water temp is higher

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Every filter plant operator’s goal for effective removal of cryptosporidium and giardia should be an effluent turbidity never greater than:
a. 0.20 NTU
b. 0.50 NTU
c. 0.40 NTU
d. 0.30 NTU
e. 0.10 NTU

e. 0.10 NTU

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Chlorine gas is about _____ times as dense as air.
a. 1/4
b. 1 1/2
c. 2 1/2
d. 3

c. 2 1/2

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Coagulation is affected by _____.
a. turbidity
b. temperature
c. pH
d. all listed

d. all listed

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Upon observing a significant increase in turbidity levels in the sedimentation basin, what is the most appropriate action for the operator to take?
a. Increase the flow rate of the influent water
b. Conduct a jar test to evaluate coagulant effectiveness
c. Reduce the chemical dosage immediately
d. Increase the sedimentation basin’s surface area

b. Conduct a jar test to evaluate coagulant effectiveness

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The loss of a blanket in an upflow solids contact clarifier will:
a. Improve tank effluent quality and lengthen filter runs
b. Improve tank effluent quality and shorten filter runs
c. Reduce tank effluent quality and lengthen filter runs
d. Reduce tank effluent quality and shorten filter runs

d. Reduce tank effluent quality and shorten filter runs

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At a softening plant, the most severe carryover of sludge in a sedimentation basin occurs when:
a. High winds are blowing in the direction of the weir
b. The sludge is too high and the flow of water has cut a “river” through it, causing severe short-circuiting
c. Incomplete coagulation-flocculation is occurring
d. The floc is composed mostly of magnesium hydroxide particles

d. The floc is composed mostly of magnesium hydroxide particles

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Which of the following sources most commonly produce water with the highest hardness?
a. Lake
b. River
c. Stream
d. Well

d. Well

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Which of the following water quality indicators do operators have the greatest control in a conventional water treatment plant?
a. Alkalinity
b. Hardness
c. Iron and Manganese
d. Turbidity

d. Turbidity

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Which is not a true statement about chlorine?
a. Chlorine is a gas, 2.5 times heavier than air
b. Concentrations in excess of 1,000 ppm may be fatal after a few breaths
c. Canister-type gas masks must be worn in situations where chlorine leaks occur
d. Chlorine is extremely corrosive in moist atmospheres

c. Canister-type gas masks must be worn in situations where chlorine leaks occur

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Before collecting a water sample for bacteriological testing aboard a ship, you should let the water run for what minimum period of time?
a. 1 min
b. 3 min
c. 5 min
d. 10 min

b. 3 min

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Which is a correct statement about chlorine?
a. Chlorine gas is colorless, odorless, and toxic
b. Chlorine gas is heavier than air
c. Chlorine gas is insoluble in water
d. Chlorine gas will liquify if heated above the boiling point of water

b. Chlorine gas is heavier than air

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Before collecting a sample for bacteriological analysis from a distribution system, how long should the water be allowed to flow to ensure accurate results?
a. 5 minutes
b. 15 minutes
c. 30 minutes
d. 60 minutes

c. 30 minutes

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Calculate flow in GPM when 1.5 MGD flowed through a filter in 24 hours:
a. 1,042 GPM
b. 1,096 GPM
c. 1,000 GPM
d. 1,200 GPM

a. 1,042 GPM

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A disadvantage of too large of a floc size is:
a. Uses more coagulant
b. Settles too quickly
c. Does not remove all the particles
d. Produces excessive sludge

d. Produces excessive sludge

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Trihalomethanes are synthetic organic chemicals primarily created:
a. During the coagulation process
b. During the pre-chlorination process
c. During reverse osmosis
d. During the post-chlorination process

b. During the pre-chlorination process

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Chemical dosage, water temp, pH, _____, and the characteristics of the raw water all have an effect on the coagulation process.
a. aeration
b. manipulation
c. settling
d. mixing

d. mixing

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What is the recommended procedure for sealing an abandoned well to prevent contamination of nearby water sources?
a. Plug the well with cement
b. Leave the well open for natural drainage
c. Fill the well with sand
d. Cover the well with a wooden cap

a. Plug the well with cement

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What characterizes a confined aquifer in relation to water pressure?
a. It is surrounded by permeable rock layers
b. It is under natural pressure due to being enclosed by impermeable layers
c. It has a direct connection to the surface
d. It is always found at depths

b. It is under natural pressure due to being enclosed by impermeable layers

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If excess floc is being carried over into your filters, what should the operator do?
a. Slow down the sedimentation process
b. Slow down the flash mix
c. Shut down the plant
d. Apply more coagulant

a. Slow down the sedimentation process

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If the static water level in a well remains the same, and the drawdown is decreasing, what is the most likely cause?
a. The aquifer is being recharged more rapidly
b. The sphere of influence has changed
c. The well pump is losing its efficiency
d. The aquifer is being depleted

c. The well pump is losing its efficiency

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When disinfecting a new or repaired main, what is the minimum chlorine residual at the extreme end of the main after standing for 24 hours?
a. 15 mg/L
b. 20 mg/L
c. 25 mg/L
d. 30 mg/L

c. 25 mg/L

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A total chlorine dosage of 6.9 mg/L is required for disinfection. If the effluent flow is 3.2 MGD and the hypochlorite used has 65% available chlorine, how many pounds/day of hypochlorite will be required? a. 274 lbs/day b. 158 lbs/day c. 512 lbs/day d. 395 lbs/day

a. 274 lbs/day

How does a reduction in water temperature influence the efficacy of chlorine as a disinfectant? a. It enhances the disinfecting action b. It has no effect on the disinfecting action c. It decreases the disinfecting action d. It increased the chlorine demand

c. It decreases the disinfecting action

Calculate the total mass of chlorine required daily at a water treatment plant if the chlorine dosage is set at 15.0 mg/L and the facility processes 2,500 cubic meters of water each day: a. 37.5 kg/day b. 25.0 kg/day c. 15.0 kg/day d. 45 kg/day

a. 37.5 kg/day

When taste and odor problems are experienced in a water supply, an examination of the water should be conducted to determine the: a. Presence of algae or diatoms b. Presence of high DO concentrations c. Presence of coliform bacteria d. Most probable number

a. Presence of algae or diatoms

Why is it so crucial to avoid rinsing prepared water sample bottles before collecting samples for bacteriological analysis? a. To prevent contamination from external sources b. To allow for proper filtration of the sample c. To ensure accurate measurement of turbidity d. To maintain the integrity of the sodium thiosulfate

d. To maintain the integrity of the sodium thiosulfate

If sequestration of iron and manganese is used, the chlorine residual in the water system should always be maintained at or above: a. 0.2 mg/L b. 0.4 mg/L c. 0.5 mg/L d. 1.0 mg/L

a. 0.2 mg/L

Chlorine feed rate in lbs/day, may be calculated from: a. Chlorine residual and chlorine demand b. Chlorine dose and chlorine demand c. Chlorine dose and average daily flow rate d. Chlorine residual and average daily flow rate e. Chlorine demand and average daily flow rate

c. Chlorine dose and average daily flow rate

Proper backwashing of a sand filter is accomplished when the filter media expands by _____%. a. 25% - 30% b. 30% - 50% c. 40% - 45% d. 60% or more e. None of the above

b. 30% - 50%

In order for water to be considered safe to drink, it must contain: a. No coliforms b. No gram ( - ) bacteria c. Less than 20 coliforms per 100 mL d. Less than 1 coliform per 100 mL

d. Less than 1 coliform per 1 mL

The total chlorine residual in water is defined as the sum of _____ present in the water after disinfection. a. only free chlorine b. only combined chlorine c. free chlorine and combined chlorine d. chlorine gas and chloramines

c. free chlorine and combined chlorine

The number of water (distribution) samples that must be taken each month is based upon: a. The amount of water sold b. The size of the population served c. The size of the territory served d. The total length (miles) of pipelines in the distribution system

b. The size of the population served

What is the primary purpose of a sanitary well seal in water treatment operations? a. Prevent contamination of the well water b. Enhance water flow rate c. Reduce sediment in the well d. Increase chlorine residuals

a. Prevent contamination of the well water

When backwashing a filter, care must be taken to prevent entrainment of the medium, causing bed removal. This is accomplished by: a. Keeping the bed packed firmly b. Keeping flow rates high c. Keeping the bed under a fine mesh strainer d. Keeping flow rates low

d. Keeping flow rates low

The difference between the static water level and the pumping water level in a well is called the: a. Specific yield b. Specific gravity c. Specific capacity d. Drawdown

d. Drawdown

The major sources for water hardness are: a. Ca2+ and Mg2+ b. CO3(2-) and Cl- c. mg2+ and Na+

a. Ca2+ and Mg2+

According to the federal Safe Drinking Water Act, systems using conventional or direct filtration must achieve turbidity levels in filtered water less than or equal to: a. 0.1 NTU in 95% of measurements taken each month b. 0.3 NTU in 95% of measurements taken each month c. 0.5 NTU in 100% of measurements taken each month d. 1.0 NTU in 75% of measurements taken each month

b. 0.3 NTU in 95% of measurements taken each month

The chlorine dose at the plant is 1.3 mg/L. The system uses 12.5% Sodium Hypochlorite. The flow rate is set at 375,000 gpd. What is the chlorine feed rate in gpd? a. 32.5 gpd b. 325 gpd c. 4 gpd d. 41 gpd

c. 4 gpd

Microscopic analysis of your water sample reveals a significant presence of protozoa and flagellates; what should you anticipate in terms of water quality issues? a. Increased risk of chemical contamination b. Potential for tastes and odor issues c. Higher likelihood of sedimentation problems d. Improved filtration efficiency

b. Potential for taste and odor issues

what are the primary concerns associated with the formation of trihalomethanes in drinking water treatment? a. They cause taste and odor issues b. They are indicators of bacterial contamination c. They are harmful byproducts formed when chlorine reacts with natural organic matter (NOM) d. They enhance the effectiveness of the disinfection process

c. They are harmful byproducts formed when chlorine reacts with natural organic matter (NOM)

In a conventional surface water treatment plant, which water quality parameter can operators most effectively manipulate through the coagulation process? a. pH b. Chlorine residual c. Turbidity d. Temperature

c. Turbidity

The presence of coliform bacteria in amounts greater than allowed by standards, indicates what? a. That the chlorine residual is not effective b. That pathogenic bacteria may be present c. That the water will positively cause disease d. That water is leaking out of the pipe

b. That pathogenic bacteria may be present

Factors that affect coagulation efficiency are: a. Concentrations of salts b. Temperature c. Mixing process d. pH range e. Alkalinity f. All of the Bove

f. All of the Above

A backwash rate that is too high can cause gravel displacement, which can lead to: a. A sand boil b. Loss of gravel into the backwash troughs c. Mudball formation d. Compaction of filter media

a. A sand boil

If an operator detects a strong odor of chlorine in a water treatment facility, but is not equipped with protective gear, what is the best immediate action to take? a. Stay in the area and try to identify the source of the odor b. Quickly exit the area while minimizing inhalation of the gas c. Open windows to ventilate the are before leaving d. Call for help while remaining in the room

b. Quickly exit the area while minimizing inhalation of the gas

What seals the top of a well to prevent contamination of the well casing? a. Sanitary seal b. Well plug c. Sand and gravel d. Grouting

a. Sanitary seal

What should you do if an operator is not breathing due to chlorine gas exposure? a. Cover the victim with a blanket b. Flush the victim's eyes with water c. Perform hands-only or conventional CPR d. Provide the victim with milk

c. Perform hands-only or conventional CPR

A filter should be backwashed in order to: a. Regenerate the filter b. Dissolve the suspended matter c. Flush the trapped impurities to waste d. Oxidize the water e. Transfer liquid in the opposite direction

c. Flush the trapped impurities to waste

The presence of any of the coliform group of bacteria in water indicates that the water: a. Is safe to drink b. Also contains typhoid bacteria c. May be dangerously contaminated or may become so d. Is being over chlorinated

c. May be dangerously contaminated or may become so

What is the chlorine dose in mg/L when 2.6 pounds were applied to a plant flow of 785,000 GPD? a. 3.3 mg/L b. 3.8 mg/L c. 4.2 mg/L d. None of the above

a. 3.3 mg/L

Why is the presence of coliform bacteria in water supplies significant for addressing water safety? a. Coliforms indicate the presence of harmful pathogens b. Coliforms are the only bacteria that can survive in chlorinated water c. Coliforms are naturally occurring in all water sources d. Coliforms are an indicator of fecal contamination

d. Coliforms are an indicator of fecal contamination

What is the MOST common (not the only one) process control parameter monitored for a mixed media water filtration system? a. Turbidity b. TSS c. Alkalinity d. Dissolved Oxygen

a. Turbidity

What is the maximum allowable turbidity level for drinking water after treatment in a well-operated filtration system? a. 0.5 NTU b. 1.0 NTU c. 2.0 NTU d. 5.0 NTU

b. 1.0 NTU

Which group of bacteria is primarily used as an indicator for potential contamination in drinking water sources? a. E. coli b. Salmonella c. Coliform group d. Staphylococcus

c. Coliform group

The purpose of a sanitary seal is to seal the: a. Pump shaft b. Top of a well casing c. Well motor d. Well vents

b. Top of a well casing

A decrease in temperature will have what effect on disinfection? a. Require longer contact time b. Require shorter contact time c. Increase rate of disinfection d. Have no effect on disinfection

a. Require longer contact time

The presence of coliform bacteria in a water distribution system: a. Is an indication that pathogenic organisms might be present b. Has no significance c. Indicates that rodents may be tunneling in the area of the pipelines d. Is positive proof that pathogenic organisms are present

a. Is an indication that pathogenic organisms might be present

Which is true about chlorine gas? a. It is 2.5 times lighter than air b. It is 2.5 times heavier than air c. It is 1.5 times heavier than air d. It is 1.5 times lighter than air

b. It is 2.5 times heavier than air

What is the optimal percentage of sand expansion recommended during backwashing of a rapid sand gravity filter to ensure effective cleaning? a. 30% b. 40% c. 50% d. 60%

a. 30%

What is residual drawdown? a. The difference between the static water level and the pumping water level in a well b. The lowering of the water table by an adjacent well pump c. If the water level in a well does not return to its original static level after pumping has stopped, the vertical distance it falls short is the residual drawdown d. The difference between the ground surface and the pumping water level

c. If the water level in a well does not return to its original static level after pumping has stopped, the vertical distance it falls short is the residual drawdown

What is the primary consequence of insufficient backwashing in a filtration system? a. Increased turbidity in treated water b. Cracking of filter media c. Reduced chlorine residual d. Improved sedimentation efficiency

b. Cracking of filter media

When backwashing a sand filter, the operator observes debris in the filter bed. Which one of the following applies? a. No surface wash b. Backwash rate insufficient c. Backwash rate too high d. Normal for a sand filter

b. Backwash rate insufficient

As temperature increases, the ability of water to contain oxygen (in mg/L) _____. a. increases b. decreases c. remains about the same

b. decreases

What can lead to the destabilization of floc during the coagulation process? a. Insufficient coagulant dosage b. Excessive flocculator paddle speed c. Low water temperature d. High turbidity levels

b. Excessive flocculator paddle speed

What should an operator do when taking a sample for bacteriological analysis? a. Always rinse the bottle with water before taking the sample and let the water run for 10 to 15 minutes b. Let the water run until there is a representative sample before filling the bottle and quickly cap it after collecting the sample c. Take no special precaution in order to have a more representative sample d. Take the sample at the kitchen sink whenever possible to obtain a better representative sample and let the water run for 10 minutes

b. Let the water run until there is a representative sample before filling the bottle and quickly capping it after collecting the sample

When working with chlorine gas leaks or releases, the operators should don a _____ and _____ for minimum protection. a. SCBA; "A" suit b. dust mask; gloves c. SCBA; respirator d. goggles; gloves

a. SCBA; "A" suit

What is the consequence of a compromised sludge blanket in an upflow clarifier? a. Enhance the removal of suspended solids b. Improve effluent clarity c. Deteriorate effluent quality and decrease sedimentation efficiency d. Increase the operational lifespan of the clarifier

c. Deteriorate the effluent quality and decrease sedimentation efficiency

What is a pathogen? a. A disease related to wastewater b. A marker organism that indicates a successful ASP c. A disease-causing organism d. A disease-preventing organism

c. A disease-causing organism

When checking the sedimentation basin immediately before filtration, the operator notices an extreme amount of floc carryover. What is the best corrective measure to take? a. Speed up flocculators b. Slow down flocculators c. Run a jar test to check chemical feed d. Do nothing, as the filters will solve the problem

c. Run a jar test to check chemical feed

The jar test is designed to represent which stage of the water treatment process? a. Rapid mix b. Coagulation c. Flocculation d. Sedimentation e. All of the Above

e. All of the Above

A treatment plant had a flow of 5.5 MGD and the desired chlorine dosage is 3.5 mg/L. How many tons per week would be used, if the chlorine were 100% gas? (one ton = 2,000 lbs) a. 0.56 tons b. 1123.8 tons c. 160.55 tones d. 56 tons

a. 0.56 tons

Which of the following factors can influence the efficiency of the coagulation process in water treatment? a. pH level b. Flow rate c. Type of coagulant used d. All of the Above

d. All of the Above

What is the water treatment process designed to destroy disease-causing microorganisms? a. Fluoridation b. Disinfection c. Coagulation d. Filtration

b. Disinfection

What is a possible disadvantage of chlorine disinfection? a. Formation of organic material in water b. Chlorine can be carcinogenic c. Formation of disinfection byproducts d. Disinfection process is not complete when water leaves the plant

c. Formation of disinfection byproducts

What does the presence of sediment accumulation in the filter bed after backwashing suggest about the backwashing process? a. The backwash flow rate is insufficient b. The filter media is too course c. The filter is operating efficiently d. The backwash duration is too long

a. The backwash flow rate is insufficient

Which of the following conditions enhances the efficiency of sedimentation in a water treatment process? a. Rabid, turbulent flow across the basin b. Uniform, horizontal, low-velocity flow across the basin c. High-velocity, chaotic flow patterns in the basin d. Irregular, chaotic flow patterns in that basin

b. Uniform, horizontal, low-velocity flow across the basin

What water quality indicator is of greatest concern in a surface water treatment plant? a. Turbidity b. pH c. Chlorine residual d. Temperature

a. Turbidity

In an artesian system, the water-bearing bed is confined by an impermeable bed, both above and below, which is referred to as an: a. Aquifer b. Aquiclude c. Aquifer recharge zone d. Aquifer pressure zone

b. Aquiclude

What happens if the velocity of water leaving the sedimentation basin is too high? a. The sedimentation basin may float b. Floc particles will grow too large in size c. Settled solids will become too compacted d. Floc may be carried over tot he filters

d. Floc may be carried over to the filters

An operator applied 19 kg of chlorine over a 3-day period. The plant flow is 4.6 ML/day. The average chlorine dose is: a. 1 mg/L b. 1.1 mg/L c. 1.4 mg/L d. 2.9 mg/L

c. 1.4 mg/L

Chlorine gas is: a. 1.5 times heavier than air b. 2 times lighter than air c. 2 times heavier than air d. 2.5 times lighter than air e. 2.5 times heavier than air

e. 2.5 times heavier than air

What is the main reason a well operated water plant will try to maintain turbidity readings from 0.3 to 0.3 NTU's? a. To reduce the load on the filters b. To avoid consumer complaints c. High turbidity will shield bacteria and pathogenic organisms from the disinfection process d. To avoid solids buildup in the distribution system that will require additional flushing

c. High turbidity will shield bacteria and pathogenic organisms from the disinfection process

Which of the following is most important when determining if water is safe to drink? a. The absence of coliform organisms in the water b. The clarity of water c. The absence of undesirable odors d. The taste of the water

a. The absence of coliform organisms in the water

An aquifer is a(n): a. Flowing well b. Impervious stratum below rock c. Structure for conveying a canal over a river or open space d. Water-bearing stratum of rock, sand, or gravel

d. Water-bearing stratum of rock, sand, or gravel

How does the water temperature affect disinfection? a. Optimal disinfection occurs at 60 degrees F b. The temperature drastically changes the pH of water, which ultimately affects disinfection c. The higher the temperature, the more effective the disinfection d. Temperature has no effect on disinfection

c. The higher the temperature, the more effective the disinfection

What is the primary purpose of maintaining a sufficient backwash flow rate during the backwashing process? a. To ensure the removal of trapped particles and debris from the filter media b. To increase the pressure within the filtration system c. To reduce the water temperature in the filtration unit d. To enhance chemical dosing efficiency

a. To ensure the removal of trapped particles and debris from the filter media

Which of the following is free chlorine residual? a. The amount of chlorine in chlorinated water after demand has been met b. Chlorine needed to sterilize the water supply c. The amount of chlorine remaining in the equipment after shutdown d. Floating solids left on the chlorine contact tank

a. The amount of chlorine in chlorinated water after demand has been met

Mud balls in the sand filter media indicates what? a. Too high of a backwash rate b. Too high of a filtration rate c. Too low of a backwash rate d. Too low of a filtration rate

c. Too low of a backwash rate

The chlorine dosage of a town's water source is 4.0 mg/L. The chlorine demand for the water is 3.7 mg/L. What is the chlorine residual? a. 0 mg/L b. 0.3 mg/L c. 3.7 mg/L d. 4.3 mg/L

b. 0.3 mg/L

Which of the following best describes the term "pathogen" in the context of water quality? a. Chemical contaminants in water b. Physical particles that affect water clarity c. Nutrients that promote algal growth d. Microorganisms that can cause disease

d. Microorganisms that can cause disease

At higher temperatures, the amount of dissolved oxygen: a. Stays the same b. Increases c. Decreases d. Doubles every time the temperature raises 1 degree C

c. Decreases

The free chlorine residual in water is the amount of: a. Chlorine applied, as measured in mg/L b. Chlorine in raw water, as it comes from the water source c. Chlorides in the water d. Uncombined chlorine that remains in the water after the chlorine has been applied and allowed to react e. None of the Above

d. Uncombined chlorine that remains in the water after the chlorine has been applied and allowed to react

When a raw water analysis shows the presence of anabaena, ceratium, and oscillatoria, what problem may arise? a. Customer complaints regarding tastes and odors b. Reduced CT c. THMs d. Low pH

a. Customer complaints regarding tastes and odors

If the totalizer reading at the start of the day was 1,500 cubic meters and the reading at the end of the day was 2,450 cubic meters, what was the average flow rate in ML/day over that 24-hour period? a. 0.04 ML/day b. 0.05 ML/day c. 0.06 ML/day d. 0.07 ML/day

a. 0.04 ML/day

What is free chlorine? a. The residual chlorine existing in water in chemical combination with ammonia or organic amines b. The sum of free and combined chlorine c. Inorganic chloramines d. The concentration of residual chlorine in water which is present as dissolved gas (Cl2), hypochlorous acid (HOCl), and/or hypochlorite ion (OCl)

d. The concentration of residual chlorine in water which is present as dissolved gas (Cl2), hypochlorous acid (HOCl), and/or hypochlorite ion (OCl)

During the backwashing of a filter, it is important to achieve: a. At least 30% expansion of the entire bed b. Fluidization of the media bed without expansion c. Turbulent flow with cavitation d. Complete disinfection of all pathogenic organisms

a. At least 30% expansion of the entire bed

During a filter backwash, a surface wash arm is found below the media surface. What is the MOST likely cause? a. The media is bound b. Too few backwash cycles c. Too many cells online at once d. Inadequate backwash length

d. Inadequate backwash length