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Water Treatment Plant Operator Test Questions > Coagulation And Flocculation Questions > Flashcards

Coagulation And Flocculation Questions Flashcards

1
Q

What you call the clumping together of very fine particles into large particles (floc) after the edition of a chemical?

A

Coagulation

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2
Q

WTP operators are mainly concerned with particles that have what type of charge?

A

Negative charge

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3
Q

The capacity of water to neutralize acid is called?

A

Alkalinity

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4
Q

What parameter is measured when water is titrated with 0.2 N (H²SO⁴) to a pH of 4.5?

A

Total alkalinity

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5
Q

Water color that includes not only the color due to substances in the water, but suspended matter as well is called?

A

Apparent color

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6
Q

Water color that includes not only the color due to substances in the water, but suspended matter as well is called?

A

Apparent color

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7
Q

Water color of a sample that has had turbidity removed is called ?

A

True color

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8
Q

A polymer that has a positive charge is?

A

Cationic polymer

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9
Q

A polymer that is often used as a filter aid is called?

A

Non-ionic

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10
Q

Where is the filter aid added?

A

Filter influent

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11
Q

A negatively charged polymer is called

A

Anionic

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12
Q

A collection of individual samples obtained at regular intervals, usually every one or two hours during a 24-hour period and combined in proportion to the flow is called?

A

Composite sample

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13
Q

⭐ A contaminant formed by the reaction of disinfection chemicals, with other substances in the water being disinfected is called?

A

Disinfectant by- product ( DBP)

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14
Q

The gathering together of fine particles after coagulation to form large particles by a process of gentle mixing is called?

A

Flocculation

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15
Q

A single sample of water collected at a particular time and place, which represents the composition of the water only at the time and place, is called?

A

Grab sample

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16
Q

What test is used to determine the correct chemical dose during water treatment?

A

Jar test

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17
Q

⭐ The sum of the atomic weight of the element in a compound is used to determine?

A

Molecular weight

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18
Q

A sample portion of water that is as nearly identical in content and consistency as possible to that in the larger body of water being sampled is called?

A

Representative sample

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19
Q

⭐ a condition that occurs in tanks or basins when some of the flowing water entering a tank or basin flows along a nearly direct pathway from the inlet to the outlet is known as?

A

Short- circuiting

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20
Q

⭐ The cloudy appearance of water caused by the presence of suspended and colloided matter is called?

A

Turbidity

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21
Q

⭐ What parameter is obtained when you measure the optical property of water based on the amount of light reflected by suspended particles?

A

Turbidity

22
Q

What are three types of solids found in water?

A

Settable, suspended, and dissolved

23
Q

When the coagulant sodium aluminate is added to water, what happens to the pH?

A

pH goes up

24
Q

When aluminum Sulfate (alum) is added to the water. What happens to the pH?

A

The pH goes down

25
Q

When the alum dosage is decreased, what generally happens with the lime dosage?

A

Lime dosage decrease

26
Q

When the alum dosage is increased, what normally takes place with the lime dose?

A

Lime dosage increases

27
Q

A physical and chemical reaction occurring between the alkalinity of the water and the chemical added which results in the formation of insoluble floc is called?

A

Coagulation

28
Q

When using alum as a coagulant, the most effective pH range for the water is?

A

Between 5 and 7 pH

29
Q

What is the best pH range for coagulation?

A

It depends on the coagulant used

30
Q

What water treatment process is known as “flashmix”?

A

Coagulation

31
Q

The coagulation process requires what amount of detention time?

A

Less than a minute, a few seconds

32
Q

The flocculation process takes place in what length of time?

A

5 to 30 minutes

33
Q

Reducing the speed of the mixers in each succeeding tank to lower the turbulence is called?

A

Tapered energy mixing

34
Q

What type of floc should be formed during flocculation?

A

Discrete and fairly dense, popcorn. Flake

35
Q

What is considered the best chemical dosage obtained during coagulation?

A

The dosage, which produces finish water that meets drinking water standards at the lowest cost.

36
Q

During the jar test, the floc starts to settle before the mixer is turned off, and 80% of the floc is settled within 1 to 2 minutes. What does this indicate?

A

Overdosage

37
Q

Jar tests are useless unless?

A

Applied and verified

38
Q

During a jar test, the floc starts settling after the mixer is turned off and 80% of the flock settles within 15 minutes. What does this indicate?

A

Good settling dosage

39
Q

During a plant tour, the operator notices a small, well dispersed floc throughout the flow. What action is needed?

A

None. This is good treatment

40
Q

⭐ If the operator does not notice a small, well-dispersed floc, what is a likely cause?

A

Chemical dosage or feed rate too low; flash mixer not providing effective mixing

41
Q

The water treatment plant is using alum as a coagulant. The floc being formed is tiny. What does this indicate?

A

Under dosage

42
Q

In the solids contact unit, the water appears to have a bluish tiny or milky color. What is the likely cause?

A

Overdose of alum

43
Q

As the floc enters the flocculation basin, the size of the floc increases. As it flows through the basin the floc starts to break up. What is the likely cause?

A

Flocculator/ floc mixer speed too high

44
Q

In question 43, what action is needed to correct the problem?

A

Reduce flocculator speed or increase dosage

45
Q

⭐ during a plant tour, the operator notices floc flowing over the laundering Weirs. What is the likely cause?

A

Floc too light for the detention time produced by the flow rate / coagulant underdosage / alkalinity too low

46
Q

⭐ in problem 45, alum is the coagulant being used. The floc is too tiny and has a very fine appearance. What is the likely cause?

A

Alum underdose, correct by increasing the dosage.

47
Q

If alkalinity is an important factor in coagulation, what parameters in the water must the operator measure?

A

Alkalinity

48
Q

⭐ if the turbidity of the raw water increases, what action is usually taken to ensure good coagulation?

A

Increase coagulant dosage

49
Q

When water temperature decreases, what action is needed to ensure good coagulation?

A

Increase coagulant dosage

50
Q

In enhanced coagulation, where is the acid added?

A

Prior to coagulation

Water Treatment Plant Operator Test Questions (16 decks)

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