water operator certification sixth edition Flashcards
The two most important factors impacting the effectiveness of chlorination are
A. pH of the water and the content of foreign substances in the water
B. concentration of chlorine and the content of foreign substances in the water
C. concentration of chlorine and contact time
D. pH and temperature of the water
C. concentration of chlorine and contact time
The treatment process that controls corrosion or scaling is known as
A. chemical control
B. stabilization
C. passivation
D. Corrosion kinetics
B. stabilization
Permanganate reactions are highly dependent upon
A. organics in the water
B. pH
C. temperature
D. alkalinity
B. pH
It is hardest to kill the organism that causes which one of the following illnesses?
A. Cholera
B. Typhoid
C. Cryptosporidiosis
D. Infectious hepatitis
C. Cryptosporidiosis
Disinfection of water wells with free chlorine requires exposure for _______ at a concentration of _______.
A. 6 to 12 hours; 25 mg/L
B. 12 to 24 hours; 25 mg/L
C. 12 to 24 hours; 50 mg/L
D. 24 to 48 hours; 100 mg/L
C. 12 to 24 hours; 50 mg/L
Which index determines the calcium carbonate deposition property of water by calculating the saturation pH, where a negative value indicates corrosive water and a positive value indicates depositing water?
A. Baylis curve
B. Langelier saturation index
C. Marble test
D. Ryzner index
B. Langelier saturation index
The advantage to using the oxidant ozone is that it
A. Is easily generated using relatively little energy
B. is easily fed into the treatment process
C. Is non-corrosive
D. Has little pH effect
D. Has little pH effect
Pretreatment with chlorine is being eliminated at many water treatment plants because it has been shown to
A. React with floc and not much with organics, pathogens, or algae, thus it is a waste or resources and money
B. react with organics almost exclusively and not much with pathogens or algae, thus it is a waste of resources and money
C. Sometimes produce disinfection by-products known to be carcinogenic
D. React by as much as 95% of its concentration with concrete walls and metal structures before oxidizing pathogens, organics, and algae
C. Sometimes produce disinfection by-products known to be carcinogenic
CTs are based on
A. Concentration of chlorine, contact time, and pH
B. Concentration of chlorine, contact time, pH, and temperature
C. Concentration of chlorine, contact time, pH, and impurities
D. Concentration of chlorine, contact time, alkalinity, pH, and temperature
B. concentration of chlorine, contact time, pH, and temperature
If the natural fluoride content of the raw water is variable, the concentration of the raw water should be measured
A. Every 8 hours
B. every 12 hours
C. Every day
D. Continuously
C. Every day
What is the primary drawback for facilities that use ultraviolet light to disinfect water?
A. It does not inactivate all microorganisms
B. it has the potential to produce trihalomethanes
C. Dissolved colloids can shield microorganisms from the UV light
D. There is potential for the light bulbs to be coated with light-obscuring material, preventing the UV light from killing microorganisms
D. There is potential for the light bulbs to be coated with light-obscuring material, preventing the UV light from killing microorganisms
Potassium permanganate is most effective in
A. Color removal
B. control of biological growth
C. Control of Trihalomethanes formation potential
D. Removing iron
D. Removing iron
Chlorine is advantageous over Chloramines in that chlorine
A. Is a much stronger oxidant
B. has long history of use
C. Has simple feeding
D. Has a persistent residual
A. Is a much stronger oxidant
Which oxidant has the potential of producing ClO₃ by-products?
A. Chlorine dioxide
B. chlorine
C. Chloramines
D. Calcium hypochlorite
A. Chlorine dioxide
How thick should the layer of sodium fluoride crystals be maintained in a saturation tank for flows of less than 100 gpm?
A. 6 inches
B. 10 inches
C. 1 foot
D. 2 feet
A. 6 inches
Which disinfectant would work best against Cryptosporidium?
A. Ozone
B. Dichloramine
C. Chlorine dioxide
D. Hypochlorous acid
A. Ozone
Which chemical oxidant would be best to use for controlling Trihalomethanes formation potential?
A. Chloramines
B. chlorine dioxide
C. Oxygen
D. Potassium permanganate
D. Potassium permanganate
Ozone generators
A. Must be supplied extremely dry air
B. are usually plate type generators for large water plants
C. Will produce about 12% ozone by weight when supplied with air
D. Will produce about 20% ozone by weight when supplied with oxygen only
A. Must be supplied with extremely dry air
A conventional treatment plant has raw water with high organic content. Respectively, name the most probable oxidants and disinfectants to use, if the plant applies oxidants/disinfectants at the (1) rapid mix chamber, (2) prefilter, at the (3) clearwell, and (4) clearwell effluent, and a long lasting residual is required.
A. (1) chlorine; (2) sodium hypochlorite; (3) sodium hypochlorite; (4) Chloramines
B. (1) Chloramines; (2) chlorine; (3) chlorine; (4) Chloramines
C. (1) potassium permanganate; (2) chlorine; (3) chlorine; (4) Chloramines
D. (1) hydrogen peroxide; (2) Chloramines; (3) Chloramines; (4) Chloramines
C. (1) potassium permanganate; (2) chlorine; (3) chlorine; (4) Chloramines
If air is used to generate ozone, which percentage of the air is usually converted to ozone?
A. 1 to 3%
B. 4%
C. 5 to 6%
D. 9 to 11%
A. 1 to 3%
Detention time in flocculation basins are usually designed to provide for
A. 5 to 15 minutes
B. 15 to 45 minutes
C. 45 to 60 minutes
D. 60 to 90 minutes
B. 15 to 45 minutes
Alum works best in a pH range of
A. Less than 4.0
B. 4.0 to 5.5
C. 5.8 to 7.5
D. Greater than 9.0
C. 5.8 to 7.5
Which statement is true concerning Collodial particles?
A. Collodial particles are so small that gravity has little effect on them
B. the zeta potential between Collodial particles is balanced by covalent bonding
C. Electrical phenomenon of Collodial particles predominate and control their behavior
D. The surface are of Collodial particles is very small compared to their mass
A. Collodial particles are so small that gravity has little effect on them
Which natural electrical force keeps Collodial particles apart in water treatment?
A. Van der Waals forces
B. Ionic forces
C. Zeta potential
D. Quantum forces
C. Zeta potential
The zeta potential measures the number of excess __________ found on the surface of all particulate matter.
A. Electrons
B. ions
C. Cations
D. Protons
A. Electrons
Low temperature water can be compensated for when using alum by
A. Increasing the pH
B. decreasing the pH
C. Increasing the alum dosage
D. Decreasing the alum dosage
C. Increasing the alum dosage
Which is the optimal pH range for the removal of particulate matter, when using alum as a coagulant?
A. 4.5 to 5.7
B. 5.8 to 6.5
C. 6.5 to 7.2
D. 7.3 to 8.1
C. 6.5 to 7.2
Which forces will pull particles together once they have been destabilized in the coagulation-flocculation process?
A. Van der Waals forces
B. Zeta potential
C. Ionic forces
D. Quantum forces
A. Van der Waals forces
Which is a common mistake that operators make in regards to flocculation units?
A. Excessive flocculation time
B. lack of food-grade NSF-approved grease on the Flocculator bearings
C. Keeping the mixing energy the same in all flocculation units
D. Too short a flocculation time
A. Excessive flocculation time
Ferric sulfate has which advantage over aluminum sulfate (alum)?
A. Less staining characteristics
B. less cost
C. More dense floc
D. Not as corrosive
C. More dense floc
How much alkalinity as CaCO3 will dry-basis alum consume?
A. 0.5 mg/L
B. 0.8 mg/L
C. 1.2 mg/L
D. 1.5 mg/L
A. 0.5 mg/L
Natural zeolites used for softening that have become exhausted with use are regenerated by immersing them in a strong solution of which chemical?
A. NaCl
B. NaOH
C. HCl
D. H₂SO₄
A. NaCl
Sodium Chlorite (salt)
The zeta potential on a particular sample of water is -2. The degree of coagulation is best described as
A. Poor
B. fair
C. Excellent
D. Maximum
C. Excellent
Which is a disadvantage of using static mixers?
A. They do not provide good mixing
B. they are not economical
C. They increase head loss
D. They require too much maintenance
C. They increase head loss
Which is the usual effective pH range of iron salt coagulants?
A. 3.5 to 9.0
B. 6.5 to 8.8
C. 3.0 to 9.5
D. 4.2 to 9.0
A. 3.5 to 9.0
To help avoid short circuiting, which is the minimum recommended number of flocculation basins in a series?
A. 2
B. 3
C. 4
D. 5
B. 3
Which type of polymer(s) is (are) sometimes formulated with regulated substances?
A. Polyethylene
B. Divinylbenzene
C. Polypropylene and polyethylene
D. Nonionic and anionic polymers
D. Nonionic and anionic
Which is the most probable solution if rotifiers are visible in the finished water?
A. Superchlorinate the water plant
B. optimize coagulation, flocculation, and filtration
C. Use aeration followed by lime softening before the settling process
D. Use oxygen deprivation
B. optimize coagulation, flocculation, and filtration
The best addition for water that is highly colored due to organic matter would be
A. The addition of lime
B. lime addition with increase in the coagulant being used
C. A small increase in a nonionic polymer
D. The addition of an acid to lower pH before coagulation
D. The addition of an acid to lower pH before coagulation
If the activation process of silica is not carefully controlled,
A. The silica could splash due to high heat of reactants
B. it could inhibit floc formation
C. It could corrode and destroy the metal and rubber in the flocculators
D. It could deposit silica on the flocculators and the gears, bringin it eventually to a grinding halt
B. it could inhibit floc formation
Which device collects the settled water as it leaves the sedimentation basin?
A. Effluent weir
B. Effluent flow bow
C. Effluent baffle
D. Effluent launder
D. Effluent launder
In solid-contact basins with fairly constant water quality parameters, how often should the solids concentrations be determined?
A. At least once per week
B. At least every other day
C. At least once per month
D. At least twice per day
D. At least twice per day
The definition of decant is
A. To draw off a liquid layer from a vessel of any size without disturbing any layer(s) above or below
B. to draw off the sediment at the bottom of a vessel of any size without disturbing the overlying liquid layer(s)
C. To remove the precipitate at the bottom of any vessel
D. To draw off the liquid from a vessel of any size without stirring up bottom sediment
D. To draw off the liquid from a vessel of any size without stirring up bottom sediment
How often should sedimentation basins with mechanical sludge removal equipment be drained and inspected?
A. Twice a year
B. once a year
C. Every other year
D. Every three years
B. once a year
Which is the most important reason to reduce turbidity?
A. To reduce taste and odor problems
B. to remove pathogens
C. To reduce corrosion
D. To determine the efficiency of coagulation and filtration
B. to remove pathogens
If enteric disease-causing protozoans have been found in the effluent of a water plant, which is the most probable solution?
A. Where possible, use powdered activated carbon (PAC) throughout water plant; back washing filters will remove the PAC
B. Use PAC only in the sedimentation basin; back washing the filters will remove the PAC
C. Use multibarrier approach-coagulation, flocculation, sedimentation, and filtration
D. Superchlorinate the water plant
C. Use the multibarrier approach-coagulation, flocculation, sedimentation, and filtration
Which is the major cause of short circuiting in a sedimentation basin?
A. Open basins that are subject to algal growths and thick slime growths on the side of the basins
B. basins without a wind break
C. Poor inlet baffling
D. Density currents
C. Poor inlet baffling
Conventional sedimentation has a _________removal of Cryptosporidium oocysts.
A. Less than 0.5 log
B. 0.5 log
C. 1.0 log
D. 2.0 log
A. Less than 0.5 log
In solids-contact basins, the weir loading normally should not exceed _______ of weir length.
A. 1 gpm/ft
B. 2 gpm/ft
C. 5 gpm/ft
D. 10 gpm/ft
D. 10 gpm/ft
Dissolved-air flotation is particularly good for removing
A. Sulfides
B. inorganics
C. Manganese and iron
D. Algae
D. Algae
Which determines whether or not Collodial-sized particles in suspension repel each other, stay in suspension, or agglomerate and eventually settle?
A. Number of collisions
B. flow and temperature of the water
C. Types of chemical bonding
D. Magnitude of the charges
D. Magnitude of the charges
If the sludge in a sedimentation basin becomes too thick, which could happen?
A. Gases from decomposition will rise through the settled sludge accelerating normal floc settling
B. abundant Trihalomethanes and haloacetic acids will form
C. Solids can become resuspended or taste and odors can develop
D. The sludge will compact at the bottom of the basin making it very difficult to remove
C. Solids can become resuspended or taste and odors can develop
In basins using tube and plate settlers, which parameter must be much better than conventional treatment basins?
A. Metals must be oxidized before reaching the tubes and plates
B. floc rate must be 2 to 3 times slower than conventional basins
C. Floc rate must be 3 to 4 faster than conventional basins
D. Floc must have good settling characteristics
D. Floc must have good settling characteristics
Which type of sedimentation basins have the flow of water admitted at an angle?
A. Rectangular settling basins
B. square settling basins
C. Center-feed settling basins
D. Spiral-flow basins
D. Spiral-flow basins
At which minimum angle must self-cleaning tube settlers be placed?
A. 50 degrees
B. 60 degrees
C. 65 degrees
D. 70 degrees
A. 50 degrees
If nematodes are interfering with the disinfectant, which is the most probable solution?
A. Optimize the settling process
B. use Chloramines
C. Decrease detention time of finished water in clearwell and tanks
D. Use oxygen deprivation
A. Optimize the settling process
At which angle should the parallel inclined plates be installed when using the shallow-depth sedimentation method?
A. 35 degrees
B. 45 degrees
C. 50 degrees
D. 60 degrees
B. 45 degrees
Why do solids-contact basins have much shorter detention times than conventional treatment basins?
A. Because chemical reactions take place throughout the basin
B. because the settling zone water moves Howard, while at the same time the mixing zone moves upward
C. Because the gentle Howard flow of the water throughout the basin is conducive for producing larger settleable floc
D. Because of the recycled materials from the sludge blanket, the chemical reactions occur more quickly and completely in the mixing area
D. Because of the recycled materials from the sludge blanket, the chemical reactions occur more quickly and completely in the mixing area
The pulsating energy in a pulsator clarifier helps to
A. Maintain a uniform sludge blanket layer
B. mix the coagulants with the raw water
C. Mix the coagulant aids with the primary coagulant and water to help in flocculation.
D. Raise the sludge blanket over the weir for wasting
A. Maintain a uniform sludge blanket layer
Pulsator clarifiers are used to treat water that is
A. Low in temperature, usually
B. high in color and low in turbidity
Which is the filtration flow rate through a manganese greensand pressure filter at 10 degrees Celcius?
A. 1 to 2 gpm/sq ft
B. 2 to 3 gpm/sq ft
C. 3 to 5 gpm/sq ft
D. 5 to 8 gpm/sq ft
B. 2 to 3 gpm/sq ft
When a filter is ripening,
A. It is in need of a backwash
B. turbidity is just starting to breakthrough
C. It is becoming more efficient in particle removal
D. It is beginning to grow algae in the filter bed, walls, and troughs
C. It is becoming more efficient in particle removal
Virgin greensand can be regenerated by soaking the filter bed for several hours in a solution of chlorine containing
A. 50 mg/L Cl₂
B. 75 mg/L Cl₂
C. 100 mg/L Cl₂
D. 200 mg/L Cl₂
C. 100 mg/L Cl₂
Which role does the action of straining of suspended particles play during filtration?
A. Minor
B. Fair
C. Good
D. Major
A. Minor
The turbidity of settled water before it is applied to the filters (post sedimentation process) should always be kept below
A. 1 to 2 NTU
B. 2 to 4 NTU
C. 5 NTU
D. 8 to 10 NTU
A. 1 to 2 NTU
Which is the best process for the removal or turbidity?
A. Anion exchange
B. Coagulation, flocculation, sedimentation, and filtration
C. Chemical oxidation
D. Granular activated carbon
B. Coagulation, flocculation, sedimentation, and filtration
If filter run times between back washes are long, for example one wee, because high quality ( low turbidity) water is being applied to the filters, which problem could still arise?
A. Mudball formation
B. Air binding and formation of mudballs
C. Extended backwashing due to media becoming too compacted
D. Floc breakthrough
D. Floc breakthrough
Gravel displacement in a filter bed from backwash rates with too high of a velocity could eventually cause
A. Compaction of the filter media
B. loss of media into the backwash troughs
C. A sand boil
D. Bed shrinkage
C. A sand boil
Virgin greensand
A. Does not require regeneration
B. requires regeneration with Potassium permanganate (1 hour soak with 60 grams KMnO₄/cu ft)
C. Requires regeneration with manganese dioxide (2 hour soak with 25% by weight solution of MnO₂)
D. Requires regeneration with manganese hydroxide (4 hour soak with 200 grams Mn(OH)₂/cu ft)
B. requires regeneration with potassium permanganate (1 hour soak with 60 grams KMnO₄/cu ft)
Which conventional treatment step is eliminated by direct filtration?
A. Oxidation
B. Aeration
C. Flocculation
D. Sedimentation
D. Sedimentation
If crustaceans have clogged the water treatment plant’s filters, which is the most probable solution?
A. Shut down the filters and physically remove them
B. shut down one filter at a time and drain; once the crustaceans have died, physically remove them and then repeat the process on the other filters
C. Backwash filters using a very high concentration of ozone in the water
D. Use a disinfectant that targets the specific organisms in question
D. Use a disinfectant that targets the specific organisms in question
Which organism can escape coagulation and thus pass through a granular filter?
A. Giardia
B. Entamoeba
C. Cryptosporidium
D. Naegleria
C. Cryptosporidium
Reverse osmosis membranes will compact faster with
A. Higher iron content
B. higher chlorine contact
C. Higher pressure
D. Higher pH
C. Higher pressure
Which would immediately occur if newly installed manganese greensand was not skimmed of the fines after backwashing and stratification steps were completed?
A. Uneven flow through the bed
B. Cracks would develop in the bed
C. Mudball formation
D. Shorter filter runs
D. Shorter filter runs
When a filter is operated at normal flow rates, it’s ability to trap flocculated particles in suspension is a function of
A. Effective size multiplied by uniformity coefficient.
B. effective size multiplied by uniformity coefficient divided by media size
C. Media depth and media size
D. Media depth and uniformity coefficient
C. Media depth and media size
Which is the best solution if iron bacteria are causing corrosion problems in the filters?
A. Protect the metal parts of the filters by adding zinc orthophosphate
B. optimize the settling process
C. Superchlorinate
D. Add lime at 50 mg/L to one filter at a time
C. Superchlorinate
A conventional water treatment plant with dual media filters has very cold water in the winter and warm water in the summer. Which should the operator do to compensate for this temperature change?
A. Use more coagulants in the summer per million gallons
B. sustain the same bed expansion without media loss by reducing or increasing backwash flow rate
C. Increase summer bed expansion and increase winter backwash flow rates
D. Increase bed expansion in the winter compared to summer in order to remove turbidity
B. sustain the same bed expansion without media loss by reducing or increasing backwash flow rate
How are reverse osmosis membranes cleaned once they become fouled?
A. They are soaked in high purity industrial soap for at least 24 hours
B. they are cleaned with an acid wash
C. They are cleaned with an acid, then with an industrial soap for 24 hours
D. They are cleaned first with a high purity industrial soap and then soaked in an acid solution for 3 days
B. they are cleaned with an acid wash
Which membrane process is used to treat brackish water or seawater?
A. Micro filtration
B. nano filtration
C. Reverse osmosis
D. Ultrafiltration
C. Reverse osmosis
The amount of reject water from a reverse osmosis unit is dependent on the number of stages in which the membranes are configured and the
A. Feed pressure
B. amount of cations
C. Amount of cations and anions
D. pH of the wat
A. Feed pressure
In the precipitative softening plant, which percentage of solids sludge is produced?
A. 1%
B. 5%
C. 10%
D. 30%
B. 5%
Which sludge disposal method is most economical for lime-soda ash softening plants?
A. Disposal into the sewage system
B. Sand drying beds
C. Lagoons
D. Landfill the sludge
C. Lagoons
Current regulations require water treatment wastes to be monitored
A. Daily
B. weekly
C. Monthly
D. Quarterly
A. Daily
Which process is used to concentrate sludge?
A. Sand bed
B. Solar lagoon
C. Thickener
D. Centrifuge
C. Thickener
Which process is used to dewater sludge?
A. Wash water basin
B. sand bed
C. Thickener
D. Reclamation basin
B. sand bed
Which is the total concentration of dissolved solids in the waste water from regeneration of ion exchange units?
A. 10,000 to 20,000 mg/L
B. 20,000 to 30,000 mg/L
C. 35,000 to 45,000 mg/L
D. 45,000 to 60,000 mg/L
C. 35,000 to 45,000 mg/L
Which is the usual range of percent sludge solids, if the sludge is allowed to accumulate and compact at the bottom of a sedimentation basin?
A. 2-4%
B. 4-7%
C. 7-12%
D. 12-15%
A. 2-4%
Which should be determined first before an in-ground sedimentation tank is drained?
A. The solids content
B. The hazardous metals content
C. Sludge volume and volume of process area to make sure it will be large enough
D. Water table level
D. Water table level
Which sludge dewatering process is best for alum sludges (which are difficult to dewater) when cakes are very dry, filtrate is clear, and solids capture is very high?
A. Centrifuge
B. Vacuum filters
C. Filter press
D. Belt filter press
C. Filter press
Which sludge dewatering process requires a precoat of diatomaceous earth and it’s use has declined due to other newer methods?
A. Centrifuge
B. Vacuum filters
C. Filter press
D. Belt filter press
B. Vacuum filters
Which national law regulates underground disposal of wastes in deep wells?
A. The Toxic Substances Control Act (TSCA)
B. The Comprehensive Environmental Response Compensation, and Liability Act (Superfund)
C. The Resource Conservation and Recovery Act (RCRA)
D. The Safe Water Drinking Act
D. The Safe Water Drinking Act
Which is typically the percentage of solid material of alum sludge?
A. 0.1-2.0%
B. 2.0-5.0%
C. 4.0-7.0%
D. 5.0-15.0%
A. 0.1-2.0%
Which is the most troublesome operating problem for sedimentation basins?
A. Algae and slime growths
B. Short-circuiting
C. Density currents
D. Sludge collection and removal
D. Sludge collection and removal
100,000 gallons of sludge is removed from a sedimentation basin at 0.2 percent (2,000 mg/L) solids and is sent to a thickener where it is expected to be concentrated to 5 percent (50,000 mg/L) before being transferred to a tank truck for hauling. If the tank truck has 4,000 gallons capacity, how many trips will be necessary?
A. One truckload
B. two truckloads
C. 5 truckloads
D. 20 truckloads
A. One truckload
Sludge produced by water drawn from sources with relatively low turbidity
A. Is high in silt and organic content
B. is high in liquid content
C. Can be very gelatinous and difficult to handle
D. Handles like clay
C. Can be very gelatinous and difficult to handle
Which precipitates can foul a cation exchange resin?
A. Sodium chloride and potassium chloride
B. chlorate and borate
C. Sulfates
D. Iron and manganese
D. Iron and manganese
Which process works best for sequestering manganese?
A. Sodium silicate alone
B. Sodium silicate and chlorine
C. Polyphosphates alone
D. Polyphosphates and chlorine
D. Polyphosphates and chlorine
When should polyphosphates used for sequestration of iron and manganese from a well be injected into the process?
A. Right after disinfection
B. immediately after aeration to remove unwanted gases
C. Right after clarification
D. Right after the water leaves the well
D. Right after the water leaves the well
Recarbonation is
A. Adding CO₂ to the water
B. Adding bicarbonate to the water
C. Adding acid to precipitate the excess lime
D. Adding caustic soda
A. Adding CO₂ to the water
In the ion-exchange softening process, once the resin can no longer soften water it must be
A. Renewed
B. re-catalyzed
C. Regenerated
D. Recharged
C. Regenerated
Ion exchange processes can typically be used for direct groundwater treatment as long as turbidity and ________ levels are not excessive.
A. Calcium carbonate
B. iron
C. Carbon dioxide
D. Sodium sulfate
B. iron
Softened water has a high pH and a high concentration of CaCO₃. Therefore, stabilization is essential in order to prevent the CaCO₃ from precipitating out
A. In household plumbing
B. in the clearwell
C. In the distribution system
D. On the filters
D. On the filters
Which is the best type of salt to use in the regeneration of ion exchange softener resin?
A. Fine-grained salt
B. Block salt
C. Block or road salt
D. Rock salt or pellet-type salt
D. Rock salt or pellet-type salt
Powdered activated carbon is primarily used to control
A. Disinfectant by-products
B. organic compounds responsible for tastes and odors
C. Synthetic organic chemicals
D. Humid and dulcimer acids
B. organic compounds responsible for tastes and odors
Ion exchange will remove
A. All hardness
B. all hardness down to 7.4 mg/L, as CaCO₃
C. All hardness down to 17.2 mg/L, as CaCO₃
D. All hardness down to about 25 mg/L, as CaCO₃
A. All hardness
It is impossible to produce waters with a hardness of less than ______ when using the lime-soda ash process.
A. 9 mg/L
B. 17 mg/L
C. 25 mg/L
D. 50 mg/L
C. 25 mg/L
When added to water for softening purposes, soda ash will do which of the following?
A. Disinfect the wat and kill the vast majority of protozoans, viruses, bacteria, and other multicellular organisms
B. raise the pH of water to between 8.0 and 9.8 pH units
C. Add CO2 to the water
D. Add calcium alkalinity to the water
A. Disinfect the water and kill the vast majority of protozoans, viruses, bacteria, and other multicellular organisms
Magnetic ion exchange resin has been developed to remove
A. Total organic carbon
B. chlorides
C. Iron and magnesium
D. Sulfates and sulfides
A. Total organic carbon
Approximately how much carbon is lost during the reactivation process for granular activated carbon?
A. 5%
B. 7%
C. 10%
D. 15%
A. 5%
Which is the most advantageous application point for powdered activated carbon?
A. Raw water intake
B. after coagulation
C. After oxidation with chlorine
D. In the filters
A. Raw water intake
Which is the most effective method for removing tastes and odors?
A. Coagulation, sedimentation, and filtration
B. Granular activated carbon
C. Anion exchange
D. Lime softening
B. Granular activated carbon
Backwashing rate procedures should be reassessed to determine the cause of granular activated carbon loss if the loss per year exceeds
A. 2 inches
B. 4 inches
C. 6 inches
D. 8 inches
A. 2 inches
Which is the most efficient process for the removal of nitrite and nitrate?
A. Powdered activated carbon
B. granular activated carbon
C. Anion exchange
D. Cation exchange
C. Anion exchange
Which is the main problem if particle agglomeration is occurring in a filter for iron and manganese removal at the interface of the coal layer and the layer below?
A. Oxidant is too weak
B. coagulant dosage is excessive
C. Coal layer is too fine
D. Coal layer is too coarse
D. Coal layer is too coarse
“agglomeration”-1 a jumbled cluster or mass of varied parts. 2. The act or process of agglomerating
Which is the most effective method for the removal of disinfection by-products?
A. Reverse osmosis
B. Lime softening
C. Ultrafiltration
D. Granular activated carbon
D. Granular activated carbon
Under no circumstances should a composite sample be collected for which type of analysis?
A. Bacteriological
B. Total dissolved solids
C. Alkalinity
D. Turbidity
A. Bacteriological
The number of monthly distribution system chlorine residual samples required is
A. Based on water withdrawal permit limit
B. Based on size
C. Bases on population
D. Different for each state
C. Based on population
Which is (are) the ideal indicator for pathogens?
A. Salmonella species
B. coliform group bacteria
C. Gram-negative cocci
D. Gram-negative coccobacilli
B. coliform group bacteria
When one substance is dissolved in another and will not settle out, which is the product called?
A. An emulsion
B. A compound
C. A suspension
D. A solution
D. A solution
Acids, bases, and salts lacking carbon are
A. Ketones
B. Aldehydes
C. Organic compounds
D. Inorganic compounds
D. Inorganic compounds
Which type of sample should always be collected for determine the presence of coliform bacteria?
A. Time composite
B. Grab sample
C. Proportional
D. Composite
B. Grab sample
Samples to be tested for coliforms can be refrigerated for up to ______ hours before analysis, but should be done as soon as possible.
A. 4
B. 6
C. 8
D. 12
C. 8
When a water sample is acidified, the final pH of the water must be
a. <3.5
a. <2.0
Which chemical is used to remove residual chlorine from water?
A. Na₂S₂O₃
B. Na₂SiO₃
C. Na₂SiF₆
D. NaOCL
A. Na₂S₂O₃
When a sample is collected, which causes its quality to begin to change?
A. CO₂
B. Dissolved gases
C. Biological activity
D. pH
C. Biological activity
Water that is to be analyzed for inorganic metals should be acidified with
A. Dilute Hydrochloric acid
B. Concentrated Hydrochloric acid
C. Dilute nitric acid
D. Concentrated nitric acid
D. Concentrated nitric acid
A solution used to determine the concentration of another solution is called a
A. Saturated solution
B. standardized solution
C. Concentrated solution
D. Dilute solution
B. standardized solution
Which method would you use to concentrate and retrieve low numbers of bacteria from a large quantity of water?
A. Colilert
B. Colisure
C. Membrane filtration
D. MPN (Most Probable Number)
C. Membrane filtration
A typical coliform colony in the membrane filter method has the following characteristics:
A. Blue with lustrous surface sheen
B. Pink to dark red with green metallic surface sheen
C. Pink or yellow with lustrous to metallic surface sheen depending on species
D. Yellow with silver metallic to lustrous surface sheen
B. Pink to dark red with green metallic surface sheen
In the presumptive phase of the Most Probable Number test, how long does it take for the coliforms to produce gas?
A. 12 to 24 hours
B. 24 to 48 hours
C. 24 to 36 hours
D. 36 to 48 hours
B. 24 to 48 hours
Chemical analysis for synthetic organic compounds should not be collected in containers made of
A. Polytetrafluoroethylene
B. stainless steel
C. Polypropylene
D. Borosilicate
C. Polypropylene
How much acid per 100 mL should be used to preserve a sample for later hardness analysis?
A. 0.1 mL
B. 0.2 mL
C. 0.5 mL
D. 1.0 mL
C. 0.5 mL
Conductivity measurements can assist the laboratory analyst in
A. Measuring the electrical strength, which is directly proportional to the number of free electrons
B. Estimating the concentration of calcium carbonate
C. Evaluating variations in the concentration of suspended particles
D. Determining the degree of mineralization of the water
D. Determining the degree of mineralization of the water
Water that is to be analyzed for inorganic metals should be filtered for __________ before _________ .
A. Dissolved metals; analysis
B. suspended metals; analysis
C. Dissolved metals; preserving
D. Suspended metals; preserving
C. Dissolved metals; preserving
In routine water quality sampling, which one of the following is an early warning sign that conditions are becoming more conducive to sulfate-reducing bacteria?
A. Increase in ferrous iron
B. Increase in ferric iron
C. Dramatic decline in dissolved oxygen
D. Increase in sulfides
C. Dramatic decline in dissolved oxygen
Which type of violation requires an all clear notification to the public?
A. Tier I
B. Tier II
C. Tier III
D. Tier IV
A. Tier I
How many coliform positive samples are allowed each month for water systems that collect less than 40 samples per month?
A. 1
B. 2
C. 3
D. 4
A. 1
If a water sample tests positive for coliforms, the system must collect a set of repeat samples within
A. 18 hours
B. 24 hours
C. 36 hours
D. 48 hours
B. 24 hours
A public water system has at least ______ service connections or serves ________ or more persons ________ or more days each year.
A. 15; 15; 50
B. 25; 25; 50
C. 15; 25; 60
D. 25; 50; 60
C. 15; 25; 60
Where are the sampling points located for required sampling of coliform bacteria in a community water systems?
A. At consumers’ faucets
B. 75% at locations representative of population distribution and 25% at the farthest points in the distribution system
C. At points where water enters the distribution system
D. At representative points within the distribution system
A. At consumers’ faucets
Water being served to the public for a population greater than 3,300 must not have a disinfectant residual entering the distribution system below _______ for more than 4 hours.
A. 0.1 mg/L
B. 0.2 mg/L
C. 0.3 mg/L
D. 0.4 mg/L
B. 0.2 mg/L
Which is the Action Level for copper?
A. 0.5 mg/L
B. 1.0 mg/L
C. 1.3 mg/L
D. 1.8 mg/L
C. 1.3 mg/L
Where are the sampling point(s) located for required sampling of turbidity in a community water system?
A. Representative points within the distribution system
B. 75% at locations representative of population distribution and 25% at the farthest points in the distribution system
C. Point(s) where water enters the distribution system, including all filter effluents if a surface water treatment plant
D. Effluents of all filters if a surface water treatment plant, entry points to the distribution system and at locations representative of population distribution
C. Point(s) where water enters the distribution system, including all filter effluents if a surface water treatment plant
Under the Surface Water Treatment Rule, disinfection residuals must be collected at the same location in the distribution system as
A. Coliforms
B. Total trihalomethanes
C. Disinfectant by-products
D. Alkalinity, conductivity, and pH for corrosion studies
A. Coliform samples
Which is the Maximum Contaminant Level for haloacetic acids (HAA5)?
A. 0.040 mg/L
B. 0.060 mg/L
C. 0.080 mg/L
D. 0.100 mg/L
B. 0.060 mg/L
If a water system collects at least 40 samples per month for analyses of total coliforms, which percent of total coliform positive samples are acceptable for the system to remain in compliance with the maximum contaminant level for total coliforms?
A. No more than 2%
B. No more than 3%
C. No more than 4%
D. No more than 5%
D. No more than 5%
Water systems are required to achieve at least ________ removal and/or inactivation of viruses between a point where the raw water is not subject to recontamination by surface water runoff and a point downstream before or at the first customer.
A. 2 log
B. 2.5 log
C. 3 log
D. 4 log
D. 4 log
Where are the sampling points located for required sampling of organics (except trihalomethanes) in a community water system?
A. Representative points within the distribution system
B. 75% at locations representative of population distribution and 25% at the farthest points in the distribution system
C. Entry points to the distribution system
D. Entry points to the distribution system and representative points within the distribution system
C. Entry points to the distribution system
Where are the sampling point(s) located for required sampling of natural radionuclides in a community water system?
A. Consumer’s faucet
B. Representative points within the distribution system
C. Each entry point to the system
D. 75% at locations representative of population distribution and 25% at the farthest points in the distribution system
C. Each entry point to the system
Continuous chlorine residual monitoring is required where the water system enters the distribution system under the Surface Water Rule when the
A. Population served is greater then 3,300 people
B. population served is greater then 10,000 people
C. Number of taps is greater then 1,000
D. Number of taps is greater then 2,500
A. Population served is greater then 3,300 people
A community water system must post the Consumer Confidence Report on a publicly accessible Web site if it serves more than
A. 10,000 people
B. 25,000 people
C. 50,000 people
D. 100,000 people
D. 100,000 people
Public Water Systems that cannot meet the required removal of TOC can comply if the source-water TOC level is ______, calculated quarterly as a running annual average.
A. Less than 1.0 mg/L
B. Less than 2.0 mg/L
C. Less than 2.5 mg/L
D. Less than 5.0 mg/L
B. Less than 2.0 mg/L
To avoid filtration, one criterion is that the fecal coliform concentration must be equal to or less than _______ in representative samples of the source water immediately before the first or only point of disinfectant application in at least ______ of the measurements made for the previous 6 months that the system served water to the public on an ongoing basis.
A. 5/100 mL; 95%
B. 10/100 mL; 99%
C. 20/100 mL; 90%
D. 25/100 mL; 90%
C. 20/100 mL; 90%
Water systems may be allowed by their state to monitor annually, if the state has determined that the system is reliable and consistently below the maximum contaminant level for organic compounds. When must the water system collect these annual samples?
A. During the fall when plant debris starts to increase in surface waters
B. During the spring when plant debris has had time to decay and thus increase organic levels in surface waters
C. During the month that previously yielded the highest analytical result
D. During the quarter that previously yielded the highest analytical result
D. During the quarter that previously yielded the highest analytical result
Water treatment operators must strike a balance between TOC removal and the
A. Stage 1 Disinfectant/Disinfection By-products Rule
B. Stage 2 Disinfectant/Disinfection By-products Rule
C. Filter Backwash Recycle Rule
D. Lead and Copper Rule
D. Lead and Copper Rule
The main purpose of mechanical seals is to
A. Keep lubrication in and dirt and other foreign materials out
B. Control water leakage from the stuffing box
C. Keep contamination from entering or leaving
D. Save on costs, as they last longer than packing
B. control water leakage from the stuffing box
The purpose of packing is to
A. Keep oil or graphite on the shaft
B. control water leakage along the pumps shaft
C. Prevent water leakage from the pump shaft
D. Help prevent shaft from warping
B. control water leakage along the pumps shaft
Which part of a pump houses the packing or mechanical seal?
A. The shroud
B. The stuffing box
C. The volute
D. The casing head
B. The stuffing box
Which is the only type of pump that can be operated against a closed valve?
A. Vertical turbine-pump
B. Centrifugal pump
C. Axial-flow pump
D. Mixed-flow pump
B. Centrifugal pump
Which is a principal problem associated with preliminary treatment screening?
A. Broken screens
B. Excessive downtime due to numerous shear pins being broken
C. Clogging
D. Chain comes out of foot sprocket
C. Clogging
Which device applies an even pressure to the packing such that it compresses tight around the pump shaft?
A. Lantern ring
B. Mechanical seal
C. Packing gland
D. Seal cage
C. Packing gland
When using four packing rings, the rings should be staggered at
A. 45 degrees
B. 90 degrees
C. 120 degrees
D. 189 degrees
B. 90 degrees
How is velocity head expressed mathematically?
A. V/g
B. V²/g
C. V²/2g
D. V²/32.2 ft/sec²
C. V²/2g
What type of centrifugal pump impeller is used for pumping medium-sized solids?
A. Open
B. Closed
C. Semi-open
D. Radial
C. Semi-open
The shaft’s main function is to transmit _______ from the motor to the impeller.
A. Centrifugal force
B. torque
C. Kinetic energy
D. Thrust
B. Torque
A single chlorine cylinder is delivering 48 lb/d of chlorine to the water process, causing the cylinder to form frost. Which would be the best solution to this problem?
A. Install a fan to improve air circulation
B. Heat the cylinder immediately below the valve with heat tape
C. Heat the valve only
D. Add another cylinder and feed from both
D. Add another cylinder and feed from both
The pressure-reducing and shutoff valve on a vaporizer will shut off when ther is a(n)
A. Loss of electrical power
B. high water level
C. High water temperature
D. Over-pressurization of the vaporization system
A. Loss of electrical power
Particle counters used the principal of light
A. Scattering
B. reflection
C. Refraction
D. Blockage
D. Blockage
How much time does it usually take to slake lime in the detention-time lime slaker?
A. 20 to 30 minutes
B. 30 to 45 minutes
C. 45 to 60 minutes
D. 60 to 75 minutes
A. 20 to 30 minutes
At which temperature should the slaking process be maintained?
A. 120 degrees Fahrenheit
B. 135 degrees Fahrenheit
C. 150 degrees Fahrenheit
D. 160 degrees Fahrenheit or higher
D. 160 degrees Fahrenheit
When external seal water is used as a water source, which should its pressure be in relation to the volute pressure?
A. 3 to 10 psi higher
B. 10 to 15 psi higher
C. 20 to 25 psi higher
D. 25 to 30 psi higher
B. 10 to 15 psi higher
Under which conditions are regenerative turbine pumps used?
A. High head conditions
B. Low head conditions
C. High volume conditions
D. Low suction conditions
A. High head conditions
Approximately, which percentage of flow increase occurs when a two-flight screw pump is changed to a three-flight screw pump, all other things being equal?
A. 10%
B. 20%
C. 33%
D. 40%
B. 20%
The arrangement of pumps in series is primarily used to increase the
A. Flow, usually by 70-80%
B. Discharge head
C. Flow, but keep discharge head the same
D. Pump efficiency
B. discharge head
How much will a flexible disk coupling compensate for in angular movement?
A. 1.0 degree
B. 2.0 degrees
C. 3.2 degrees
D. 3.7 degrees
B. 2.0 degrees
Which is the most important thing to consider in automatic startup after a power failure?
A. Operator safety
B. Power surges that could trip a breaker
C. Importance to process
D. Importance to water quality
A. Operator safety
At which range of temperatures will fusible plugs on chlorine cylinders melt?
A. 147 to 152 degrees Fahrenheit
B. 155 to 159 degrees Fahrenheit
C. 157 to 162 degrees Fahrenheit
D. 167 to 171 degrees Fahrenheit
C. 157 to 162 degrees Fahrenheit
When a chlorine cylinder or container is changed, a new gasket should be used
A. Every time
B. After 2 uses
C. After 3 uses
D. After 4 or 5 uses
A. Every time
Which is the best type of gasket to use when connecting a chlorine cylinder or container to the chlorine feed system?
A. Fiber gasket
B. Aluminum gasket
C. Copper gasket
D. Lead gasket
D. Lead gasket
Which part of the human body is the most vulnerable to allowing microorganisms to enter it?
A. Stomach area where most of the organs are located
B. Heart
C. Eyes
D. Throat or neck area
C. Eyes
Which will occur if dry alum and quicklime are mixed together?
A. Highly explosive hydrogen gas will be released
B. Dust may be released which may cause an explosion
C. A coagulated gel will form
D. Nothing, as they are neutral towards each other
A. Highly explosive hydrogen gas will be released
Chlorine gas
A. Will burn in the presence of oxygen and moisture
B. Will explode in the presence of oxygen and an ignition source
C. Will support combustion
D. Will conduct electricity
C. Will support combustion
Chlorine storage rooms should
A. Have sealed walls and doors that open inward
B. Be fitted with chlorine-resistant power exhaust fans ducted out at ceiling level
C. Have lights and fans on the inside and wired to the same switch
D. Have a window in the door so an operator can look into the room to detect any abnormal conditions
D. Have a window in the door so an operator can look into the room to detect any abnormal conditions
Before an authorized entrant enters a permitted confined space,
A. He or she must don SCUBA gear
B. the internal atmosphere of the space must be tested to measure oxygen content, presence of flammable gases and vapors, and potentially toxic air contaminants
C. Verify the availability of rescue services
D. Ensure ther is adequate lighting in the space to conduct the necessary work
B. the internal atmosphere of the space must be tested to measure oxygen content, presence of flammable gases and vapors, and potentially toxic air contaminants
Fluoride injection should be as far away as possible from any chemical that contains
A. Chlorine
B. aluminum (from alum)
C. Calcium
D. Sodium (for example, soda ash)
C. Calcium
Water treatment personnel should only use self-contained breathing apparatus equipment that has been approved by
A. The Occupational Safety and Health Administration
B. their state’s Department of Public Health
C. The National Institute of Occupational Safety and Health
D. The American Standards and Testing Methods
C. The National Institute of Occupational Safety and Health
If a substantial chlorine leak incident occurs, which agency should be called for actual hands-on assistance?
A. The Occupational Safety and Health Administration (OSHA)
B. The Chemical Transportation Emergency Center
C. The Transportation Emergency Institute
D. The Chlorine Institute
B. The Chemical Transportation Emergency Center
In regards to safety, wet activated carbon will remove which from the air?
A. Organic gases and hydrogen sulfide
B. Oxygen
C. Carbon dioxide
D. Carbon monoxide
B. Oxygen
An employee’s average airborne exposure in any 8-hour shift in a 40-hour workweek that should not be exceeded is called
A. Short Term Exposure Limit (STEL)
B. Time-Weighted Average (TWA)
C. Threshold Limit Value (TLV)
D. Recommended Exposure Limits (REL)
B. Time-Weighted Average (TWA)
Sites are required to do a site assessment under the process safety management (PSM) regulations (OSHA) if the facility in a single process has more than how many pounds of chlorine?
A. 1,000 lb
B. 1,500 lb
C. 2,000 lb
D. 4,000 lb
B. 1,500 lb
Which factor is used to express the relative volatility of a substance?
A. Chaitin’s constant
B. Feigenbaum constant
C. Henry’s constant
D. Boyle’s Law
C. Henry’s constant
Ammonia gas can be fatal to humans at concentrations as low as
A. 500 ppm
B. 900 ppm
C. 1,400 ppm
D. 2,000 ppm
D. 2,000 ppm
Which emergency kit is for chlorine tank cars?
A. Kit A
B. Kit B
C. Kit C
D. Kit D
C. Kit C
Each year approximately which percentage of confined space deaths are would-be rescuers?
A. 25%
B. 50%
C. 67%
D. 75%
C. 67%
When a water source is destroyed or damaged due to some disaster that causes total contamination, which would be a short-term goal?
A. Install a dual potable-nonpotable water system
B. Construct a new raw water source
C. Clean up the source of contamination caused by the disaster
D. Draw water from an adjoining system or systems
D. Draw water from an adjoining system or systems
The organisms used to indicate the likelihood that pathogenic bacteria may be present are
A. Salmonella bacteria
B. Enteric viruses
C. Coliform bacteria
D. Pseudomonas group bacteria
C. Coliform bacteria
Which adverse effects does the secondary contaminant manganese have?
A. Unappealing to drink, undesirable taste, and possible indication of corrosion
B. discolored laundry and changed taste of water, coffee, tea, and other beverages
C. Undesirable metallic taste and possible indication of corrosion
D. Added total dissolved solids and scale, indication of sewage contamination and tastes
B. discolored laundry and changed taste of water, coffee, tea, and other beverages
In general, which causes an increase in taste and odors when natural waters lack dissolved oxygen?
A. Increase in algae growth
B. pH reduction causing an increase in iron and manganese going into solution
C. Anaerobic decomposition
D. Oxidation of organic material
C. Anaerobic decomposition
A physical property, as opposed to a chemical property, important to water treatment is
A. Turbidity
B. pH
C. Dissolved solids
D. Electrical conductivity
A. Turbidity
Which are the two principal chemicals that cause water hardness?
A. Aluminum and iron
B. Aluminum and calcium
C. Iron and manganese
D. Calcium and magnesium
D. Calcium and magnesium
Temporary hardness is caused by
A. Magnesium sulfate
B. calcium nitrate
C. Magnesium chloride
D. Calcium bicarbonate
D. Calcium bicarbonate
Which type of algae would most likely be found in nutrient-rich waters?
A. Blue-green algae
B. Green algae
C. Diatoms
D. Brown algae
A. Blue-green algae
The quantity of dissolved oxygen in water is a function of
A. pH, alkalinity, temperature, and total dissolved solids
B. temperature, and alkalinity
C. pH and temperature
D. Temperature, pressure, and salinity
D temperature , pressure, and salinity
Most of the carbon dioxide in groundwater originates from
A. Weathering of rocks
B. Biological oxidation of organic matter
C. Animal respiration
D. Plant respiration
B. biological oxidation or organic matter
At which temperature does the maximum density of water occur?
A. -0.4 degrees Celcius
B. 0.0 degrees Celcius
C. 0.4 degrees Celcius
D. 4.0 degrees Celcius
D. 4.0 degrees Celcius
When water freezes it expands by ________ of its original volume.
A. One-twentieth
B. one-fortieth
C. One-ninth
D. One-seventh
C. One-ninth
Which type of polar bonds are between the hydrogen atoms and the oxygen atom in water?
A. Ionic
B. Covalent
C. van der Waals
D. Hydrogen bonding
B. Covalent
Which would be the most probable solution to control algae in the source water if the algae were clogging the filters at the water plant?
A. Use activated carbon
B. decrease oxygen levels
C. Backwash filters more frequently
D. Control nutrients
D. Control nutrients
Total dissolved minerals in rainwater are typically close to
A. 0.05 mg/L
B. 1.00 mg/L
C. 10.00 mg/L
D. 40.00 mg/L
C. 10.00 mg/l
Because manganese is only slightly soluble, it is rarely found in surface waters above a concentration of
A. 1.0 mg/L
B. 2.0 mg/L
C. 2.5 mg/L
D. 3.0 mg/L
A. 1.0 mg/L
Where does the microbial growth that affects groundwater sources and thus the treatment for removing iron and manganese occur?
A. Anaerobic zone
B. Aerobic zone
C. Reduction zone
D. Where aerobic and anaerobic conditions meet
D. Where aerobic and anaerobic conditions meet
Which conditions will +Eh values of water support?
A. Anaerobic activities
B. Aerobic activities
C. Low pH values
D. Organic acid production
B. Aerobic activities
Radon is a radioactive decay daughter of
A. Uranium 235
B. uranium 238
C. Radium 226
D. radium 228
C. Radium 226
Which algal genera are most likely to cause taste-and-odor problems when abundant in the water?
A. Volvox
B. Chlorella
C. Oocystis
D. Spirogyra
A. Volvox
Shellfish grown in polluted waters have been known to contain the organism that causes
A. Dysentery
B. Typhoid
C. Infectious hepatitis
D. Gastroenteritis
C. Infectious hepatitis
Which is the principal scale-forming substance in water?
A. Zinc orthophosphate
B. sodium carbonate
C. Calcium
D. Calcium carbonate
D. Calcium carbonate
Which oxidant should be fed as early as possible in the treatment process to allow for complete reaction before it enters the distribution system?
A. Ozone
B. chlorine dioxide
C. Chloramines
D. Potassium permanganate
D. Potassium permanganate
The flexible copper tubing that connects a 150-lb chlorine cylinder to a manifold should be rated at
A. 100 psi
B. 150 psi
C. 250 psi
D. 500 psi
D. 500 psi
The buildup of corrosion products is a process known as
A. Deposition
B. electrochemical deposition
C. Physiochemical deposition
D. Tuberculation
D. Tuberculation
Potassium permanganate
A. Usually has a dosage range from 10 to 15 mg/L
B. oxidizes to manganese dioxide, which can give the water a purple color
C. Should be fed before chlorine
D. Should be used with powdered activated carbon (PAC)
C. Should be fed before chlorine
Low values for which water characteristics may require the addition of lime, caustic soda, or sodium bicarbonate?
A. Turbidity
B. water temperature
C. pH
D. Alkalinity
D. Alkalinity
Whic chemical could cause pink water problems?
A. Chloramine
B. Potassium permanganate
C. Bromine
D. Iodine
B. Potassium permanganate
The most frequent in situ well treatment is the application of a(n)
A. Chemical to adjust pH of well water that is either too acidic or too alkaline
B. phosphate inhibitor to prevent well pump corrosion
C. Oxidant to reduce iron bacteria
D. Coagulant for high turbidity well water
C. Oxidant to reduce iron bacteria
In situ: 1. Situated in the original, natural, or existing place or position
Which chemical is slaked lime?
A. Ca(OH)₂
B. Ca(HCO₃)₂
C. CaCO₃
D. Ca(H2O)₂
A. Ca(OH)₂
Calcium sulfate (CaSO₄) is also known as
A. Gypsum
B. Limestone
C. Dolomite
D. Talc
A. Gypsum
Which color does the oxidant potassium permanganate turn at its end point?
A. Reddish-brown
B. Red
C. Pink
D. Yellow
D. Yellow
The simplest chlorine gas feeder for controlling chlorine gas flow is
A. Constant differential pressure
B. Varible differential pressure
C. Sonic flow
D. Induction mixer
C. Sonic flow
Which is usually used to disinfect the gravel packing of a groundwater well?
A. Chlorine dioxide
B. powder of calcium hypochlorite tablet
C. Sodium hypochlorite
D. Chloramines
B. powder of calcium hypochlorite tablet
Which is true regarding chlorine one-ton containers?
A. Full one-ton containers weigh at least 4,500 pounds
B. full one-tone weigh about 2,750 pounds
C. The chlorine containers have three fusible plugs on the valve end and two on the opposite end
D. One-ton containers are equipped with two valves, one for liquid and one for gas
D. One-ton containers are equipped with two valves, one for liquid and one for gas
Teeth are likely to become pitted when the fluoride concentration in drinking water goes above which amount?
A. 3 mg/L
B. 4 mg/L
C. 5 mg/L
D. 6 mg/L
B. 4 mg/L
How many pounds of ammonia ad contained in a full 1-ton cylinder?
A. 800
B. 1,000
C. 1,500
D. 2,000
A. 800
High pH favors the formation of
A. Haloacetic acids
B. Total Trihalomethane
C. Both haloacetic acids and total Trihalomethane
D. Neither haloacetic acids nor total Trihalomethane
B. Total Trihalomethane
How often is it recommended to check the fluoride feed system?
A. At least once every 24 hours
B. every 12 hours
C. Every 8 hours
D. Every hour
D. Every hour
Low pH favors the formation of
A. Haloacetic acids
B. total Trihalomethane
C. Both haloacetic acids and total Trihalomethane
D. Neither haloacetic acids nor total Trihalomethane
A. Haloacetic acids
Dental fluorosis is
A. Dental cavities
B. mottling of the teeth
C. Fluoride dental rinse
D. Coating of fluoride on the enamel of the teeth
B. mottling of the teeth
One volume of liquid chlorine will expand to approximately how many volumes of gas?
a. 440
b. 460
c. 480
d. 484
b. 460
In general, how long does ozone last when it is dissolved in water for disinfection purposes?
a. A few seconds to a few minutes
b. 5 to 10 minutes
c. .10 to 15 minutes
d. 15 to 30 minutes
a. A few seconds to a few minutes
Sodium fluoride
a. was once called silly acid
b. is a straw yellow color
c. has a solution pH of about 1.0 pH units
d. is odorless
d. is odorless
Which does the saturation point of calcium carbonate primarily depend upon?
a. pH
b. Temperature
c. Concentration of calcium
d. TDS
a. pH
Which will increase ph, hardness, and alkalinity?
a. Sodium hydroxide
b. Zinc orthophosphate
c. Lime
d. Sodium zinc phosphate
c. Lime
How often should the fluoride concentration of treated water be measured?
a. Every 8 hours
b. Every 12 hours
c. Every day
d. Continously
c. Every day
Which is the pH of a saturated solution of sodium fluoride?
a. 6.2
b. 7.0
c. 7.8
d. 8.0 to 8.4
b. 7.0
Which is the most effective wavelength when using ultraviolet light for disinfection?
a. 2,235 angstroms
b. 2,650 angstroms
c. 2,875 angstroms
d. 2,965 angstroms
b. 2,650 angstroms
Which type of chlorine gas feeder is most commonly used?
a. Pressure
b. Combination water and pressure
c. Vacuum
d. Combination pressure and vacuum
c. Vacuum
Which substance is a depolarizer?
a. Carbonates
b. Nitrates
c. Polyphosphates
d. Silicates
b. Nitrates
Which composes the majority of scale in pipe?
a. Ca(HCO₃)₂
b. CaCO₃
c. MgCO₃
d. CaSO₄
b. CaCO₃
The specific gravity standard for gases is
a. water vapor at 100˚ C
b. air
c. oxygen
d. nitrogen
b. air
Which chemical oxidant is most effective in reducing the concentration of taste-and-odor compounds caused by actinomycetes species?
a. Chloramines
b. Peroxone
c. Chloride dioxide
d. Potassium permanganate
b. Peroxone
Which oxidant is a bluish toxic gas with a pungent odor?
a. Bromine
b. Iodine
c. Ozone
d. Potassium permanganate
c. Ozone
Past the breakpoint chlorination point, which percentage of the total chlorine residual should be free chlorine?
a. 75 to 85%
b. 85 to 90%
c. 90 to 95%
d. 100%
b. 85 to 90%
Sodium hyochlorite has a pH range of
a. 6.0 to 7.5 pH units
b. 7.5 to 8.5 pH units
c. 8.5 to 9.5 pH units
d. 9.0 to 11.0 pH units
d. 9.0 to 11.0 pH units
Where should the fluoride injection point be located?
a. Right after flocculation
b. After sedimentation, but before lime softening
c. Before filtration
d. After water has received complete treatment
d. After water has received complete treatment
The corrosion process can be accelerated by certain bacterial organisms because they produce which chemical?
a. N₂
b. CO₂
c. MgCO₃
d. CaCO₃
b. CO₂
Which chemical would be best to use for corrosion inhibition if the water is very low in alkalinity and calcium concentration?
a. Sodium carbonate
b. Sodium bicarbonate
c. Sodium hydroxide
d. Polyphosphates
d. Polyphosphates
If the temperature drops below _____ a 50% solution of caustic soda will begin to crystallize.
a. 44℉
b. 48℉
c. 54℉
d. 58℉
c. 54℉
When chlorine has destroyed all reducing compounds, any chlorine remaining will react with
a. nitrite and form chloramines
b. nitrates and form chloramines
c. ammonia and form chloramines
d. organics and form aromatics
c. ammonia and form chloramines
Low values for which water characteristic usually cause poor coagulation, flocculation, and settling characteristics?
a. Water temperature
b. Turbidity
c. Alkalinity
d. pH
a. Water temperature
Polyphosphates would most likely give the best results at
a. high alkalinity levels
b. high water temperatures
c. low pH values
d. high pH values
c. low pH values
Which is the most effective disinfectant for inactivating bacteria?
a. Hypochlorite ion
b. Hypochlorus acid
c. Chloramines
d. Bromine
b. Hypochlorus acid
Which chemical oxidant is the weakest?
a. Potassium permanganate
b. Ozone
c. Choramines
d. Chlorine dioxide
c. Chloramines
Which is the density of liquid chlorine?
a. 1.25
b. 1.50
c. 2.50
d. 3.50
b. 1.50
Which device(s) uniformly disperse(s) the chlorine solution into the main flow of water?
a. Injectors
b. Pressure regulating valve
c. Diffusers
d. Effluent nozzles
c. Diffusers
The pressure in a chlorine cylinder depends on the
a. amount of chlorine in the cylinder
b. temperature of the chlorine liquid
c. vacuum placed on the regulator
d. amount of gas being withdrawn
b. temperature of the chlorine liquid
Sodium bicarbonate needs to be stored in a cool, dry place because it decomposes rapidly as the temperature nears
a. 80℉
b. 100℉
c. 115℉
d. 125℉
b. 100℉
In the breakpoint chlorination curve, in which zone do inorganic chlorine demand-causing compounds consume free chlorine?
a. Zone 1
b. Zone 2
c. Zone 3
d. Zone 4
a. Zone 1
Which is the optimal pH level for sulfate-forming reactions with chlorine?
a. 6
b. 8
c. 9
d. 11
a. 6
Liquid chlorine is which color?
a. Yellow
b. Dark green
c. Amber
d. Light brown
c. Amber
When chlorine gas is under a vacuum reliquefaction will not occur until the temperature drops below
a. -20℉
b. -30℉
c. -38℉
d. -48℉
b. -30℉
Which method can be used to control scale and corrosion?
a. Softening
b. pH and alkalinity adjustment with lime
c. Sequestering
d. Chelation
b. pH and alkalinity adjustment with lime
Which is the chemical formula for hydrated lime?
a. CaO
b. CaCO₃
c. Ca(OH)₂
d. CaMg(CO₃)₂
c. Ca(OH)₂
Once iron bacteria become established in a well, shock chlorination will be required. The shock treatment is required
a. at increasingly shorter intervals
b. at increasingly longer intervals
c. at very regular intervals
d. sporadically, depending on many physical water quality factors and specifically on pumping rates.
a. at increasingly shorter intervals
Which should accompany shock treatment to maximize its effectiveness for a well that has been fouled by iron bacteria?
a. Constant addition of more chlorine as it is consumed, as determined by chlorine wet tests
b. Air surging, valved surge blocks, or jetting
c. Slow addition of surfacants
d. 1 to 5% acid solution with the chlorine
b. Air surging, valved surge blocks, or jetting
Which should the concentration of chlorine be just before the pump is started (for surging and moving the disinfectant into the acquifer and well) in order to sufficiently disinfect a public water supply well?
a. 10 mg/L
b. 25 mg/L
c. 50 mg/L
d. 100 mg/L
c. 50 mg/L
Which compound will decrease in solubility as the temperature rises?
a. Slaked lime
b. Calcium carbonate
c. Magnesium hydroxide
d. Magnesium oxalate
a. Slaked lime
Which is the most probable solution if nitrifying bacteria are increasing the demand for the disinfectant being used?
a. Optimize nutrient control at the water plant
b. Superchlorinate reservoirs and stroage tanks
c. Increase detention time in reservoirs and the distribution systems
d. Use powdered activated carbon in the filters
b. Superchlorinate reservoirs and storage tanks
When air is used to gerate ozone, an air dryer should be used to reduce the production
a. nitrous oxides
b. hydrogen gas (H₂)
c. water
d. ammonia (NH₃)
a. nitrous oxides
Which shows the correct relative strengths of chlorine species as disinfectant?
a. HOCl > OCl > NH₂Cl > HCl
b. OCl > HOCl > NH₂Cl > HCl
c. NH₂Cl > HCl > HOCl > OCl
d. HCl > HOCl > OCl > NH₂Cl
a. HOCl > OCl > NH₂Cl > HCl
When ultraviolet radiation is used to inactrivated microorganisms, which are the optimum wavelengthes?
a. 100 to 200 nanometers (nm)
b. 250 to 265 nm
c. 330 to 360 nm
d. 400 to 500 nm
b. 250 to 265 nm
Regarding the breakpoint chlorination curve, the chlorine dosage must go beyond which point in the curve to eliminate tastes and odors?
a. Point 2
b. Point 3
c. Point 4
d. Point 5
c. Point 4
Which chemical will decrease alkalinity?
a. Silicates
b. Carbon dioxide
c. Sodium hydroxide
d. Sodium bicarbonate
b. Carbon dioxide
Which oxidant would cause the most corrosion and scaling problems?
a. Ozone
b. Chlorine dioxide
c. Chloramines
d. Oxygen
d. Oxygen
Which metal, if in contact with cast iron, would becoe the most active (anode)?
a. Aluminum
b. Zinc
c. Cadium
d. Mild
b. Zinc
Low alkalinity water becomes quite corrosive when it is heavily saturated with
a. lime
b. soda ash
c. oxygen
d. sodium bicarbonate
c. oxygen
Immediately before breakpoint chlorination occurs, which chemical species are destroyed?
a. Arobatic hydrocarbons
b. Aromatic hydrocarbons and aliphatic hydrocarbons
c. Ammonia and chloroorganics
d. Chloroorganics and chloramines
d. Chloroorganics and chloramines
Which is the most effective disinfectant for inactivating viruses?
a. Hypochlorite ion
b. Diatomic iodine
c. Chloramines
d. Chlorine dioxide
d. Chlorine dioxide
Which is the most effective disinfectant for inactivating protozoan cysts?
a. Chloramines
b. Hypochlorous acid
c. Ozone
d. Bromine
c. Ozone
Which chemical oxidant would be most effective in removing color and for controlling tastes and odors?
a. Ozone
b. Potassium permanganate
c. Chloramines
d. Chlorine
a. Ozone
Which chemical oxidant is the weakest?
a. Oxygen
b. Ozone
c. Potassium permanganate
d. Chlorine dioxide
a. Oxygen
Why can hypochlorus acid (HOCl) penetrate bacterial surfaces better than hypochlorite ion (OCl-)?
a. Because it is a proton donor
b. Because it is an acid
c. Because it is a smaller molecule than OCl- despite having a hydrogen atom; the hydrogen atom helps compact the molecule
d. Because it is neutral
d. Because it is neutral
Which chlorine compound will produce the least detectable chloronous taste and odor?
a. Hypochlorous acid
b. Monochloramine
c. Dichloramine
d. Nitrogen trichloride
b. Monochloramine
Which type of pumps would be the most economical to use if large volumes of sodium hypochlorite were required?
a. Chemical feed pumps using piston rods
b. Chemical feed pumps using plunger drives
c. Centrifugal pumps
d. Solenoid-operated pumps
c. Centrifugal pumps
A disadvantage to using chloramines is
a. their vulnerability to nitrification
b. that they cannot penetrate biofilms in the distribution system
c. their propensity to form trihalomethanes
d. that their residual persistence in the distribution system is low
a. their vulnerability to nitrification
Where is the best place to add corrosive inhibitors such that disinfection can take place under more advantageous conditions at a conventional water treatment plant?
a. Rapid mix basin
b. Pre-filter
c. Pre-clearwell
d. Post clearwell
d. Post clearwell
Which method can be used to control scaling but is never used to control corrosion?
a. Chelation
b. Controlled CaCO₃ scaling
c. Polyphosphate addition
d. pH and alkalinity adjustment with lime
a. Chelation
How much more soluble is ozone in water than oxygen?
a. 7.6 times
b. About 10.0 times
c. 12.0 times
d. 20.0 times
d. 20.0 times
Which is the most effective ratio of hydrogen peroxide to ozone?
a. 1:2
b. 2:5
c. 1:3
d. 1:4
a. 1:2
Which is the chlorine demand of nitrite?
a. 2.0 parts chlorine to 1 part nitrite
b. 2.5 parts chlorine to 1 part nitrite
c. 4.0 parts chlorine to 1 part nitrite
d. 5.0 parts chlorine to 1 part nitrite
d. 5.0 parts chlorine to 1 part nitrite
A sodium hypochlorite solution at room temperature will lose which percentage of its available chlorine per month?
a. 1 to 2%
b. 2 to 4%
c. 4 to 6%
d. 6 to 8%
b. 2 to 4%
When supplied with air, ozone generators will produce about
a. 2% ozone
b. 5% ozone
c. 7% ozone
d. 12% ozone
a. 2% ozone
Which method for chlorine dioxide generation is most likely to have substantial amounts of chlorine in solution?
a. Add chlorine to water, then this water to sodium citrate and sodium chlorate
b. Add chlorine to water, then this water to hydrochloric acid and sodium chlorate
c. Inject chlorine gas under vacuum into stream of chlorite solution
d. Add hydrochloric acid to a chlorite solution
b. Add chlorine to water, then this water to hydrochloric acid and sodium chlorate
Which chemical used for stabilitzation of potable water is a bacterial nutrient?
a. Polyphosphate
b. Lime
c. Soda ash
d. Sodium bicarbonate
a. Polyphosphate
Once formed, hypochlorus acid instantaneously establishes equilibrium as follows:
HOCl H⁺ + OCl-
hypochlorus hypoclorite
acid ion
This equilibrium reaction at 20℃ has which characteristic
a. It contains 50% of HOCl and OCl- at a pH of 7.3
b. The reaction depends on concentration
c. It responds slowly to pH changes
d. It is completely reversible
d. It is completely reversible
Ultraviolet light used in disinfection is generated by mercury or
a. germanium
b. antimony
c. cesium
d. cadium
b. antimony
The production of earthy-musty compounds, geosmin, and 2-methylisoborneol (MIB) by cyanobacteria are difficult to remove except when using
a. lime
b. ozone
c. aeration
d. filtration
b. ozone
Which chemical oxidant would be most effective for removing synthetic organics?
a. Oxygen
b. Chlorine
c. Chloramines
d. Chlorine dioxide
d. Chlorine dioxide
The advantage to using the oxidant oxygen is that it
a. is non-corrosive
b. has no by-products
c. causes small amount of scaling problems
d. is a strong oxidant
b. has no by-products
Which method for chlorine dioxide generation is best for large-scale application?
a. Add chlorine to water, then this water to sodium citrate and sodium chlorate
b. Add chlorine to water, then this water to hydrochloric acid and sodium chlorate
c. Inject chlorine gas under vacuum into a stream of chlorite solution
d. Add hydrochloric acid to a chlorite solution
c. Inject chlorine gas under vacuum into a stream of chlorite solution
Which is the commercial purity of fluorosilic acid?
a. 20 to 30%
b. 20 to 40%
c. 30 to 40%
d. 35 to 48%
a. 20 to 30%
Which type of fluoride chemical should be used in down flow saturators?
a. Tablets of sodium fluorosilicate
b. Granular sodium silicofluoride
c. Crystalline sodium fluoride
d. Powdered sodium fluoride
c. Crystalline sodium fluoride
The decomposition products of sodium hypochlorite into chlorate and O₂ would be caused by which factor?
a. Temperature
b. Metallic impurities
c. UV light
d. pH
c. UV light
Which are the only two metals that can contact sodium hypochlorite; all other metals must be eliminated from storage vessels, piping, valves, and feed equipment?
a. Titanium and tantalum
b. Titanium and germanium
c. Vanadium and germanium
d. Vanadium and selenium
a. Titanium and tantalum
Sites that require chlorine vaporizers typically have a feed rates that exceed
a. 450 lb/d
b. 800 lb/d
c. 1,000 lb/d
d. 2,000 lb/d
d. 2,000 lb/d
The deterioration of elastomeres by chloramines is enhanced by
a. higher pH
b. lower pH
c. higher temperatures
d. lower temperatures
c. higher temperatures
Most water treatment systems can limit nitrification by
a. maintaining a pH of 7.0 to 7.5
b. maintaining a chlorine to ammonia-nitrogen ratio between 4.5:1 and 5.0:1
c. limiting excess free ammonia to below 0.5 mg/L nitrogen
d. maintaining temperature between 18 and 28℃
b. maintaining a chlorine to ammonia-nitrogen ratio between 4.5:1 and 5.0:1
If the percentage of chlorine delivered to a water treatment plant in liquid form is 12.5% chlorine, which chemical is it most likely to be?
a. Calcium hypochlorite
b. Sodium hypochlorite
c. Chlorine
d. Chlorine dioxide
b. Sodium hypochlorite
How many steps are in the coagulation process?
a. 3
b. 4
c. 5
d. 6
a. 3
Polymers used as flocculants are
a. water-soluble inorganic electrolytes
b. water-insoluble organic polyelectrolytes
c. water-insoluble inorganic electrolytes
d. water-soluble organic polyelectrolytes
d. water-soluble organic polyelectrolytes
Which is the zeta potential?
a. Electrical charge on a suspended particle
b. Electrical resistance of a suspended particle
c. Electrical potential of a suspended particle
d. Electrical charge of a suspended particle as it relates electrochemically to the coagulant being used
a. Electrical charge on a suspended particle
All colloids are
a. sols
b. hydrophobic
c. electrically charged
d. emulsoids
c. electrically charged
Collodial particle movement and aggregation caused by thermal energy is called
a. orthokinetic flocculation
b. parakinetic dynamism
c. Brownian movement
d. thermodynamic flocculation
c. Brownian movement
When used with alum, which chemical improves coagulation?
a. Ferric chloride
b. Ferric sulfate
c. Sodium aluminate
d. Aluminum sulfate
c. Sodium aluminate
The coagulant alum reacts with natural alkalinity in the water forming
a. aluminum hydroxide
b. aluminum carbonate
c. aluminum bicarbonate
d. aluminum oxide
a. aluminum hydroxide
When ferric coagulants react with natural alkalinity in the water they form
a. ferric hydroxide
b. ferric carbonate
c. ferric bicarbonate
d. ferric oxide
a. ferric hydroxide
Detention time in mechanical mixers usually ranges from
a. 5 to 15 seconds
b. 15 to 45 seconds
c. 1 to 2 minutes
d. 2 to 4 minutes
b. 15 to 45 seconds
The aluminum ions in alum neutralize the negatively charged particles in the raw water in about
a. 1 to 2 seconds
b. 3 to 5 seconds
c. 5 to 8 seconds
d. 5 to 12 seconds
a. 1 to 2 seconds
Suspended and collodial solids found in natural waters are usually
a. positively charged
b. negatively charged
c. neutral
d. polyionic
b. negatively charged
After the oxidation treatment, H₂S in the water turns a milky-blue color because of elemental sulfur (solid sulfur). Which is the best procedure to remove this sulfur?
a. Adsorption
b. Sedimentation
c. Coagulation and filtration
d. Lime-soda ash softening
c. Coagulation and filtration
Particles will stay in suspension as long as the
a. ionic forces are stronger than the van der Waals forces
b. zeta potential is stronger than the van der Waals forces
c. van der Waals forces are stronger than the ionic forces
d. van der Waals forces are stronger than the zeta potential
b. zeta potential is stronger than the van der Waals forces
The most probable effective ratio of the coagulants aluminum sulfate to hydrated lime is
a. 1:1 aluminum sulfate to hydrated lime
b. 3:1 aluminum sulfate to hydrated lime
c. 5:1 aluminum sulfate to hydrated lime
d. 6:1 aluminum sulfate to hydrated lime
b. 3:1 aluminum sulfate to hydrated lime
Which should the “tip speed” of the flocculator be in water, assuming the water is not extremely cold?
a. 0.2 ft/sec
b. 0.5 ft/sec
c. 1.0 ft/sec
d. 2.0 ft/sec
c. 1.0 ft/sec
Coagulants consisting of trivalent ions are how much more effective than bivalent ions?
a. 50 to 60 times
b. 100 to 120 times
c. 200 to 250 times
d. 1,000 times
a. 50 to 60 times
When tip velocities of the impellers reach speeds greater than _____ localized shearing of floc occurs.
a. 6.0 fps
b. 8.0 fps
c. 10.0 fps
d. 10.5 fps
b. 8.0 fps
In the flash mixing process, which type of rapid mixing system has the most significant head loss?
a. Mechanical mixers
b. Static mixers
c. Pumps and conduits
d. Baffled chambers
b. Static mixers
When these types of chemicals are used, flash mixing becomes less critical, but thorough mixing (flocculation) remains very important.
a. Ferric or ferrous chloride
b. Aluminum sulfates
c. Lime, soda ash, or caustic soda
d. Polymers
d. Polymers
Weighing agents are used primarily to treat water that is
a. low in color and mineral content and high turbidity
b. high in color and mineral content and low in turbidity
c. low in turbidity and mineral content and high in color
d. high in turbidity and mineral content and low in color
c. low in turbidity and mineral content and high in color
The flash mixing process that has the best control features are
a. mechanical mixers
b. static mixers
c. pumps and conduits
d. baffled chambers
a. mechanical mixers
The zeta potential on a particular sample of water is +2. The degree of coagulation is best described as
a. poor
b. fair
c. excellant
d. maximum
d. maximum
The most effective ratio of the coagulant ferric sulfate to the oxidant chlorine is
a. 2:1 ferric sulfate to chlorine
b. 4:1 ferric sulfate to chlorine
c. 5:1 ferric sulfate to chlorine
d. 8:1 ferric sulfate to chlorine
d. 8:1 ferric sulfate to chlorine
Mixing of a coagulant is least influenced by flow when using
a. a static mixer
b. a baffled chamber
c. a pump (adding coagulant on suction side)
d. pipe grids that have been perforated
c. a pump (adding coagulant on suction side)
When alum or ferric coagulants are used to treat water, the reactions are governed by all the following. Which one is critical to floc formation?
a. Initial application at point of highest mixing intensity
b. Temperature and ratio of turbidity to coagulant
c. Alkalinity
d. Amount of turbidity
a. Initial application at point of highest mixing intensity
Seimentation depends on
a. size of flocculated particles
b. gravity
c. the depth of the basin
d. the type of coagulant used
b. gravity
Most clarifiers are designed to have a theoretical detention time of about _____ when the plant is at its maximum flow.
a. 1 hour
b. 2 hours
c. 3 hours
d. 4 hours
d. 4 hours
