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46 Cards in this Set

  • Front
  • Back

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 the chlorine and the content of foreign substances in the water.


C. Concentration of the chlorine and contact time.


D.pH and temperature of the water

C. Concentration of the 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 he following illnesses?


A. Cholera


B. Typhoid


C. Cryptosporidiosis


D. Infectious Hepatitits

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 of resource 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 produces 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 produces disinfection by-products known to be carcinogenic.

CTs are based on


A. Concentration of the chlorine, contact time, and pH


B. Concentration of chlorine, contact time, pH, and temperature


C. Concentration of chlorine, contact time, pH, and water 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. everyday


D. continuously

C. everyday

Which is the primary drawback for facilities that use UV light to disinfect water?


A. It does not inactivated all microorganisms


B. It has the potential to produce THMs


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 THM 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 saturator 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 THM formation potential?


A. Chloramines


B. Chlorine dioxide


C. Oxygen


D. Potassium permanganate

D. Potassium permanganate

Ozone generators


A. must be supplies with 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 supplies 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) chlorine


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 use 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 mins.


B. 15 to 45 mins.


C. 45 to 60 mins.


D. 60 to 90 mins.

A. 5 to 15 mins.

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 colloidal particles?


A. Colloidal particles are so small that gravity has little effect on them.


B. The zeta potential between colloidal particles is balanced by covalent bonding


C. Electrical phenomenon of colloidal particles predominate and control their behavior


D. The surface area of colloidal particles is very small compared to their mass

A. Colloidal particles are so small that gravity has little effect on them.

Which natural electrical force keeps colloidal 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 times


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 times

Ferric sulfate has which advantage over aluminum sulfate (alum)?


A. Less staining characteristics


B. Less cots


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

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 poylmers

D. Nonionic and anionic poylmers

Which is the most probable solution if rotifers are visible in the finished water?


A. Superchlorinate the water plant.


B. Optimize coagulation, flocculation, and filtration


C. Use aeration followed by lime sofetning before 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 gears, bringing 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 box


C. Effluent baffle


D. Effluent launder

D. Effluent launder

In solid-contact basins with fairly constant water quality parameters, how often should the solids concentration be determined?


A. At least once per week


B. At least once 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 size 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 powered activated carbon (PAC) throughout water plant; backwashing filters will remove the PAC


B. Use PAC only in the sedimentation basin; backwashing the filters will remove the PAC


C. Use a multibarrier approach- coagulation, floccultaion, sedimentation, and filtration


D. Supercholorinate the water plant

C. Use a multibarrier approach- coagulation, floccultaion, sedimentation, and filtration