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Water Treatment Plant Operator Test Questions > Corrosion Control > Flashcards

Corrosion Control Flashcards

(56 cards)

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1
Q

What parameter is calculated to determine smoothness of the interior of a pipe?

A

C. Factor

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2
Q

The marble test determines what water condition?

A

Scaling or corrosiveness of the water and stability of the water

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3
Q

Besides the marble test, what other devices determine the stability of water?

A

Enslow column and langular index

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4
Q

⭐ When a operator took marble retest, initial pH, alkalinity, and hardness did not change after adding calcium carbonate to water. What does this indicate?

A

Water is just saturated/stable

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5
Q

⭐. After adding 5 mL of calcium carbonate to the marble test sample, the pH, alkalinity, and hardness all went up. What does this indicate?

A

The water was undersaturated or corrosive

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6
Q

⭐. After adding 5 mL of calcium carbonate to the marble test sample, the pH, alkalinity, and hardness all went down. What does this indicate?

A

The water was over-saturated or scaling

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7
Q

⭐. How is the pH calculated?

A

Temperature, TDS, calcium, and alkalinity

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8
Q

How is langlier index determined?

A

Subtract the pHs from the pH

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9
Q

⭐. The pH is 8.6 and the pHs is 8.8. What is the L.L. ?

A
  • 0.2
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10
Q

What is the action level for lead in water?

A

0.015 MG/L

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11
Q

What is the action level for copper?

A

1.3 mg/L

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12
Q

What is the SMCL for iron?

A

0.3 mg/l

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13
Q

When is a water system deemed to be in violation of lead and copper rule?

A

When the 90th percentile test exceeds the action level for copper and lead

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14
Q

What disease is associated with excess amounts of lead and water?

A

Mental retardation in children

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15
Q

What disease is associated with excess amounts of copper in the water?

A

Wilson’s disease known as liver problems

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16
Q

If water systems have exceeded the action level for lead or copper, what action must be taken?

A

pH. Adjustment/ publicnification and education/ add a polyphosphate in the filter Influent /adcalcium carbonate

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17
Q

The water spigots aerator must remain on when drawing, lead or copper samples true or false?

A

True true

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18
Q

The destruction of metallic matter by a chemical or electrochemical reaction is called?

A

Corrosion

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19
Q

What type of corrosion originates outside the homes plumbing system?

A

Stray current (also known as electrolysis)

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20
Q

If the water velocity increases, what else will increase

A

Corrosion rate

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21
Q

What type of corrosion is associated with copper pipe?

A

Erosion corrosion

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22
Q

What kind of corrosion is caused by connecting two dissimilar metals together?

A

Galvanic corrosion

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23
Q

What is the largest source of lead in water systems?

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A

Plumbing fixtures

24
Q

What causes black water?

25
Red stain indicates what type of corrosion?
Iron
26
Black stains I'm plumbing fixtures indicate what type of corrosion is taking place
Manganese
27
What causes red water?
Iron bacteria
28
A water system using manganese green sand is getting customer complaints regarding red water. What is the likeliest cause?
Iron bacteria/greensound filter has to be regenerated with potassium premagnate / polyphosphate reverted to orthophosphate
29
If adding polyphosphate and chlorine during pretreatment, which chemical must come first?
Polyphosphate
30
What conditions are ideal for corrosion?
Hi TDS, low hardness, low pH, high DO content, high temperature, high velocity/ s also chlorine residual, bacterial, soil moisture, or high pressure
31
For corrosion to take place what must be present?
Oxygen
32
How can a water system best prevent slime from forming in the distribution system?
Maintain 0.2 MG/L chlorine residual
33
Which electrical system prevents corrosion and pitting of metal surfaces?
Cathodic protection
34
When water is stored in an open reservoir, which phosphate compound should you avoid using?
Zinc phosphate because it causes algae bloom
35
The WTP operator notices brown stains on the walls of the water filters. What does this indicate
Insoluble iron
36
The WTP operator notices black stains on the walls of the water filter. What does this indicate?
Insoluble manganese
37
The WTP operator notices brown and black stains on the walls of the water filters. What does this indicate
Insoluble iron and manganese
38
How can you tell when there is corrosion in the water main?
Rusty or red water/ musty smell / dip in DO of water since it left the WTP
39
How do you measure the corrosiveness of soil?
Soil resistance meter
40
How do you determine the correct chemical dosage for water?
Jar test/ marble test/ enslow column /trial and error experiment with computer /graphics
41
Iron in ferrous form is
Soluble
42
Iron as ferric hydroxide is?
Insoluble
43
Corrosion can be slowed by adding what to the water?
Corrosion inhibitor
44
What do you call a piece of metal that is inserted into a water main?
Coupon and is used to measure corrosion
45
What type of corrosion is caused by connecting to dissimilar metals?
Galvanic corrosion
46
A common corrosion in iron pipes is?
Tuberculation
47
The negative pole is called
Cathode
48
The dissolved oxygen (DO) was lower at the customer's home than when it left the WTP. What does this indicate? Or what caused this to happen?
Corrosion /organic matter in the water
49
The operator measured the DO at point A. He then measured it at point B downstream from point A. What does this indicate? Or what caused this to happen?
Corrosion /organic matter in the water
50
The operator dropped HCI on the copper gate of a valve? The reaction was an effervescent bubbling. What does this indicate?
A thin coat of CaCO3 on the valve part indicating the water was just saturated
51
What term is used to measure current?
Ampere
52
What term is used to measure resistance
Ohms
53
CaCO3 is less soluble in hot water than in cold water. True or false?
True
54
What is the most common source of lead found in customer's homes?
Plumbing fixtures
55
What can inhibit corrosion?
Thin layer of CACO3
56
What do you call a ring-shaped space located between two circular objects,?
Annular space

Water Treatment Plant Operator Test Questions (16 decks)

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