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Environmental Engineering 3 > The Condition Of Water > Flashcards

The Condition Of Water Flashcards

1
Q

What percentage of Earth’s water is naturally fresh?

A

3%

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2
Q

Of Earth’s natural fresh water, how much can be easily sourced?

A
  1. 1% groundwater

0. 3% surface water

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3
Q

What water contaminants are not known to be harmful but should still be removed in treatment where possible?

A

Micropollutants from cosmetics and medications

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4
Q

Why is temperature important in water treatment?

A

It affects key properties such as solubility, precipitation of solids and biological activity

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5
Q

How is the carbon content of water divided?

A

Inorganic, organic, dissolved organic

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6
Q

How are the presences of various compounds in water measured?

A

pH, alkalinity, hardness, conductivity

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7
Q

What is the source of most organic compounds in water?

A

Microbial degradation in soil

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8
Q

What are the three types of particulate and what separates them?

A

Solution: cannot be filtered, does not scatter light
Suspension: can be filtered, can scatter light
Colloid: cannot be filtered, can scatter light

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9
Q

How are total solids determined?

A

Evaporation overnight at 103-105 degrees C

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10
Q

How are total fixed solids determined?

A

Ignition of total solids in a muffle furnace

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11
Q

How are total volatile solids determined?

A

Total solids minus total fixed solids

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12
Q

How are total suspended solids determined?

A

1 hour of filtration and drying

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13
Q

How are total dissolved solids determined?

A

Drying of the liquid product of the 1 hour of filtration

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14
Q

What is the desirable limit of dissolved solids?

A

<500ppm

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15
Q

What is turbidity?

A

A measure of light scattering

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16
Q

What is Avogadro’s number?

A

6.022x10^23

17
Q

What is a Dalton?

A

An atomic mass of 1 Dalton means 1 mol weighs 1g

18
Q

When finding equivalents, how is charge important?

A

Substances with charges more positive or negative than 1 just be multiplied in equivalent quantity by the charge

19
Q

What are the ions that affect water pH?

A

Hydrogen H+ and Hydroxide OH-

20
Q

What is a buffer solution?

A

A solution which resists pH change

21
Q

What is the equation for alkalinity of water?

A

[HCO3 -]+2[CO3 2-]+[OH-]-[H+]

22
Q

What is alkalinity typically expressed in?

A

Calcium carbonate equivalent (CaCO3)

23
Q

How is alkalinity measured?

A

By the amount of strong acid that is required to reduce the pH of the solution to 4.2

24
Q

What is the main cause of scale buildup?

A

Carbonate/temporary hardness

25
Q

What is the test for biological oxygen demand?

A

The amount of oxygen consumed over 5 days at 20 degrees C

26
Q

When can biological treatment be used to adjust water’s oxygen demand?

A

When BOD/COD > 0.5

27
Q

Why must turbidity be reduced for effective disinfection?

A

Suspended particles can cause shadowing, which shelters pathogens from disinfection

28
Q

What is water hardness?

A

A measurement of metallic cations in water such as calcium and magnesium

29
Q

What metals correspond to hardness?

A

Calcium and magnesium

30
Q

What compounds are associated with non-carbonate hardness?

A

Sulphates, chlorides and nitrates

31
Q

How do you convert a concentration into equivalents?

A

Divide by molecular mass and multiply by absolute charge.

Remember concentration in mg/L or ppm go to meq/L

32
Q

In the pH curve, what dominates up to pH 6?

A

Carbonic Acid H2CO3

33
Q

In the pH curve, what dominates between pH 7 and 10?

A

Bicarbonate HCO3 -

34
Q

In the pH curve, what dominates above pH 11?

A

Carbonate CO3 2-

35
Q

How many equivalents are there per mol of CaCO3?

A

2

Environmental Engineering 3 (2 decks)

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