D2

Front 1

If the natural fluoride content of the raw water is variable, the concentration of the raw water should be measured

Back 1

Everyday

Front 2

Which is the primary drawback for facilities that use ultraviolet lights to disinfect water?

Back 2

There is potential for the light bulbs to be coated with light obscuring material, preventing the UV light from killing microorganisms

Front 3

Potassium Permanganate is most effective in

Back 3

Removing iron

Front 4

Chlorine is advantageous over chloramines in that chlorine

Back 4

Is a much stronger oxidant

Front 5

Which oxidant has the potential of producing CIO3 by products?

Back 5

Chlorine dixoide

Front 6

How thick should the layer of sodium fluoride crystals be maintained in a saturator tank for flows of less than 100 gpm?

Back 6

6 inches

Front 7

Which disinfectant would work best against Cryptosporidium?

Back 7

Ozone

Front 8

Which chemical oxidant would be best to use for controlling trihalomethanes formation potential?

Back 8

potassium permanganate

Front 9

Ozone generators

Back 9

Must be supplied with extremely dry air

Front 10

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 (1) rapid mix chamber, (2) prefilter, at the (3) clearwell, and (4) clearwell effluent, and a long lasting residual is required.

Back 10

(1) potassium permanganate; (2) chlorine; (3) chlorine; (4) chloramines

Front 11

If air is used to generate ozone, which percentage of the air is usually converted to ozone?

Back 11

1 to 3%

Front 12

Detention time in flocculation basins are usually designed to provide for

Back 12

15 to 45 minutes

Front 13

Alum works besting apH range of

Back 13

5.8 to 7.5

Front 14

Which statement is true concerning colloidal particle

Back 14

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

Front 15

Which natural electrical force keeps colloidal particles apart in water treatment?

Back 15

Zeta potential

Front 16

The zeta potential measures the number of excess _________ found on the surface of all particulate matter.

Back 16

Electrons

Front 17

Low temperature water can be compensated for when using alum by

Back 17

Increasing the alum dosage

Front 18

Which is the optimal pH range for the removal of particulate matter; when using alum as a coagulant?

Back 18

6.5 to 7.2

Front 19

Which forces will pull particles together once they have been destabilize in the coagulation flocculation process?

Back 19

Van Dr Walls forces

Front 20

Which is a common mistake that operators make in regards to flocculation units?

Back 20

Excessive flocculation time

Front 21

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

Back 21

More dense floc

Front 22

How much alkalinity as CaCO3 will dry basis alum consume?

Back 22

0.5 mg/L

Front 23

Natural zeolite used for softening that have become exhausted with use are regenerated by immersing them in a strong solution of which chemical?

Back 23

NaCl

Front 24

The zeta potential on a particular sample of water is -2. The degree of coagulation is best described as

Back 24

Excellent

Front 25

Which is a disadvantage of using static mixers

Back 25

They increase head loss

Front 26

Which is the usual effective pH range of iron salt coagulants?

Back 26

3.5 to 9.0

Front 27

To help avoid short circuiting which is the minimum recommended number of flocculation basins in a series?

Back 27

3

Front 28

Which type of polymer(s) is (are) sometimes formulated with regulated substances?

Back 28

Nonionic and anionic polymers

Front 29

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

Back 29

Optimize coagulation, flocculation, and filtration

Front 30

The best addition for water that is highly colored due to organic matter would be more

Back 30

The addition of an acid to lower pH before coagulation

Front 31

If the activation process of silica is not carefully controlled

Back 31

It could inhibit floc formation

Front 32

Which device collects the settled water as it leaves the sedimentation basin?

Back 32

Effluent launder

Front 33

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

Back 33

At least twice per day

Front 34

The definition of decant is

Back 34

To draw off the liquid from a vessel of any size without stirring up bottom settlement

Front 35

How often should sedimentation basins with mechanical sludge removal equipment be drained and inspected?

Back 35

Once a year

Front 36

Which is the most important reason to reduce turbidity?

Back 36

To remove pathogens

Front 37

If enteric disease causing protozoans have been found in the effluent of a water plant which is the most probable solution?

Back 37

Use multibarrier approach coagulation, flocculation, sedimentation, and filtration

Front 38

Which is the major cause of short circuiting in a sedimentation basin?

Back 38

Poor inlet baffling

Front 39

Conventional sedimentation his a ______ removal of cryptosporidium oocysts.

Back 39

Less than 0.5-log

Front 40

In solids-contact basins, the weir loading normally should not exceed _______ of weir length.

Back 40

10 gpm/ft

Front 41

Dissolved-air flotation is particularly good for removing

Back 41

Algae

Front 42

Which determines whether or not colloidal-sized particles in suspension repel each other stay in suspension or agglomerate and eventually settle?

Back 42

Magnitude of the charges

Front 43

If the sludge in a sedimentation basin becomes too thick, which could happen

Back 43

Solids can become resuspended or taste and odors can develop

Front 44

In basins using tube and plate settlers, which parameter must be much better than conventional treatment basin?

Back 44

Floc must have good settling chaaracteristics

Front 45

Which type of sedimentation basins have the flow of water admitted at an angle

Back 45

Spiral-flow basin

Front 46

At which minimum angle must self cleaning tube settlers be placed?

Back 46

50 degrees

Front 47

If nematode are interfering with the disinfectant, which is the most probable solution?

Back 47

Optimize the settling process

Front 48

At which angle should the parallel inclined plates be installed when using the shallow depth sedimentation method

Back 48

45 degree

Front 49

Why do solids contact basin have much shorter detention times than conventional treatment basins

Back 49

Because of the recycled materials from the sludge blanket the chemical reactions occur more quickly and completely in the mixing area