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Lesson 2 - Brewing Water Sources and Treatment Flashcards

1
Q

What are the main characteristics of potable water?

A
  • Microbiologically free of pathogens
  • Colourless and clear
  • Tasteless and odourless
  • Optimal pH close to neutral (7.0)
  • Free from heavy metal ions
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2
Q

What is the pH range of precipitation?

A

5 to 6

Precipitation starts as pure water but picks up CO2 as it falls.

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3
Q

What can cause acid rain?

A

Pollution leading to low pH as low as 2.6

Acid rain can result from sulphate and nitrate compounds.

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4
Q

What is alkalinity in water?

A

Measures dissolved alkaline substances

It buffers water at a higher pH by neutralising acids.

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5
Q

What are the three primary types of alkalinity?

A
  • Bicarbonate
  • Carbonate
  • Hydroxide
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6
Q

What is the pH range of ground water?

A

6.5 to 8.5

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7
Q

What determines water hardness?

A

Level of calcium (Ca2+) and magnesium (Mg2+) compounds

High levels indicate ‘hard’ water, while low levels indicate ‘soft’ water.

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8
Q

What is the purpose of screening in raw water treatment?

A

To remove solid objects from water

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9
Q

What is the process of coagulation in water treatment?

A

Dosing water with a chemical coagulant to bind fine suspended material

Forms flocs that settle or float for removal.

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10
Q

What role does filtration play in water treatment?

A

Removes suspended material from water

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11
Q

What is the effect of aeration in water treatment?

A

Removes volatile organics and oxidises metals

Helps in taste and odour compound removal.

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12
Q

What is granular activated carbon used for in water treatment?

A

Adsorbs organic compounds from water

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13
Q

What is the purpose of pH adjustment in water treatment?

A

To meet water quality standards and avoid corrosion

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14
Q

What disinfectant is most widely used in municipal water supplies?

A

Chlorine (Cl2)

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15
Q

What are the recommended conditions for effective disinfection of drinking water?

A

pH less than 8.0 and contact time greater than 30 minutes

Results in a free chlorine residual of 0.2 to 0.5 mg/L.

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16
Q

What are the potential risks of chlorine treatment?

A
  • Off-taste
  • Resistance of some organisms
  • Formation of organic halogen compounds
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17
Q

True or False: Ground water typically has a higher mineral content than surface water.

A

True

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18
Q

What is formed when ammonia reacts with free chlorine in water treatment?

A

Chloramines (NH2Cl)

Chloramines are less effective as disinfectants compared to chlorine but provide longer-lasting protection.

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19
Q

What are the advantages of chlorine treatment in water disinfection?

A
  • Low initial cost
  • Low running costs
  • Simplicity of handling
  • Protection against re-infection

These advantages make chlorine a popular choice for water treatment.

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20
Q

What are the disadvantages of chlorine treatment?

A
  • Off-taste requiring carbon filtration
  • Resistance of some organisms to chlorine
  • Formation of organic halogen compounds

These disadvantages can impact the quality and safety of drinking water.

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21
Q

According to the UK standards, what is the maximum concentration of Enterococci in potable water?

A

0 Number/100 mL

This standard is part of microbiological parameters for safe drinking water.

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22
Q

What is the maximum concentration of Arsenic allowed in potable water according to UK standards?

A

10 µg/L

Arsenic is a toxic element, and its presence in drinking water is strictly regulated.

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23
Q

What does total hardness in water consist of?

A

Permanent hardness + Temporary hardness

Both types of hardness affect water quality and treatment processes.

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24
Q

What is permanent hardness?

A

Hardness that cannot be removed by boiling

It includes non-carbonate salts such as sulphates, chlorides, and nitrates of calcium or magnesium.

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25
What is temporary hardness?
Hardness that can be removed by boiling ## Footnote It consists of carbonate or bicarbonate salts of calcium or magnesium.
26
What happens to temporary hardness when water is boiled?
Calcium carbonate (CaCO3) precipitates out ## Footnote This process releases CO2, impacting the water's pH.
27
What effect does high water hardness have on brewing?
Causes scaling and fouls hot water pipes ## Footnote This reduces heat transfer efficiency and can affect the brewing process.
28
How does permanent hardness affect mash pH?
It reduces mash pH ## Footnote This occurs because phosphates from malt interact with calcium and magnesium ions to release H+ ions.
29
What is the classification of water hardness according to the European Brewery Convention?
* 0-37.5 mg/L: Very soft * 37.5-87.5 mg/L: Soft * 87.5-175 mg/L: Medium hard * 175-375 mg/L: Hard * > 375 mg/L: Very hard ## Footnote This classification helps in understanding the suitability of water for brewing.
30
What is the formula to calculate total hardness as CaCO3?
Total Hardness as CaCO3 = (2.5 x Ca2+) + (4.12 x Mg2+) | 2.5 → Conversion factor for calcium 4.12 → Conversion factor for magnesi ## Footnote This formula allows brewers to determine water hardness based on calcium and magnesium levels.
31
What does alkalinity in water refer to?
The amount of strong acid required to convert carbonate and bicarbonate to CO2 at pH 4.4 ## Footnote Alkalinity affects the pH of the mash and brewing process.
32
How is total alkalinity estimated?
By titrating 100 mL of water with 0.1 M HCl to pH 4.4 ## Footnote Indicators such as bromocresol green or methyl orange can be used depending on the initial pH.
33
What is the pH level at which strong acid is required to convert carbonate and bicarbonate to CO2?
4.4
34
What is the concentration of HCl used to titrate water to pH 4.4?
0.1 M
35
What indicators can be used for titration depending on the initial pH of the water?
* Bromocresol green (if pH > 8.3) * Methyl orange (if pH < 8.3)
36
How is alkalinity expressed?
mg of CaCO3
37
What is the equivalency of 1 mL of 0.1 M HCl in terms of CaCO3?
5 mg of CaCO3
38
Who is responsible for the concept of residual alkalinity?
Paul Kolbach
39
What reaction occurs between calcium, magnesium, and phosphate compounds in brewing water?
Calcium and magnesium react with phosphates, releasing H+ ions that convert bicarbonate ions to carbonic acid.
40
What happens to carbonic acid in the brewing process?
It dissociates into carbon dioxide and water, and the carbon dioxide leaves the water.
41
What is residual alkalinity (RA)?
Alkalinity that remains after calcium and magnesium have reacted with phosphate.
42
How many equivalents of calcium are required to neutralize 1 equivalent of water alkalinity?
3.5 equivalents
43
How many equivalents of magnesium are required to neutralize 1 equivalent of water alkalinity?
7 equivalents
44
What is the formula to calculate the equivalent of an ion?
Atomic or molecular weight of the ion divided by the valence of the ion.
45
How does residual alkalinity affect mash pH?
* Positive RA increases mash pH * Negative RA lowers mash pH
46
What effect do darker malts have on mash pH?
They tend to be more acidic.
47
What is the impact of mineral levels in brewing water?
Mineral levels can significantly affect the mash and wort pH.
48
What processes are involved in converting raw water to potable water?
Removal of organic and particulate matter and disinfection.
49
50
What is alkalinity in brewing water?
Alkalinity is the water's ability to resist pH changes, mainly due to bicarbonate (HCO₃⁻), carbonate (CO₃²⁻), and hydroxide (OH⁻) ions. It is measured in ppm as CaCO₃.
51
Why is alkalinity important in brewing?
High alkalinity can prevent the mash from reaching the ideal pH (5.2–5.6), affecting enzyme activity and beer flavor.
52
What is residual alkalinity (RA)?
Residual alkalinity is the remaining alkalinity after calcium (Ca²⁺) and magnesium (Mg²⁺) have reacted with bicarbonate in the mash. It influences mash pH.
53
What is the formula for residual alkalinity (RA)?
RA = Alkalinity - (Calcium (Ca²⁺) in ppm / 3.5 + Magnesium (Mg²⁺) in ppm / 7)
54
How does calcium (Ca²⁺) affect mash pH?
Calcium lowers mash pH by reacting with bicarbonate, forming insoluble calcium carbonate.
55
How does magnesium (Mg²⁺) affect mash pH?
Magnesium also lowers mash pH but is only half as effective as calcium.
56
What happens if residual alkalinity is high (>50 ppm)?
It raises mash pH, making it more suitable for dark beers that contain acidic malts.
57
What happens if residual alkalinity is low (0–50 ppm)?
It helps keep mash pH in the ideal range, making it better for pale ales and lagers.
58
How can you lower residual alkalinity?
Add calcium (gypsum or calcium chloride), magnesium, or acid (lactic/phosphoric).
59
How can you increase residual alkalinity?
Add bicarbonate (baking soda or chalk).
60
Fill in the blank: Alkalinity is measured in _______.
ppm (mg/L) of CaCO₃.
61
True or False: High residual alkalinity is beneficial for brewing pale ales.
False.
62
What ions are mainly responsible for alkalinity in brewing water?
* Bicarbonate (HCO₃⁻) * Carbonate (CO₃²⁻) * Hydroxide (OH⁻)
63
What effect does adding bicarbonate have on residual alkalinity?
Raises RA.
64
What is the ideal pH range for mash?
5.2–5.6.
65
What is the significance of negative residual alkalinity?
Water is very acidic and will drop mash pH significantly.
66
Describe the role of the water cycle in determining the mineral composition of brewing water.
As water moves through the water cycle, it dissolves minerals from the air, soil, and rock. Surface water and groundwater have different mineral compositions, which impact their suitability for brewing.
67
What are the key characteristics that define potable water according to the World Health Organization (WHO)?
Potable water is safe for lifetime consumption. It should be microbiologically safe, colorless and clear, tasteless and odorless, have an optimal (near-neutral) pH, and be free from heavy metals.
68
Explain the purpose of coagulation and sedimentation in raw water treatment and name two chemical coagulants used in the process.
These processes remove fine suspended materials. Coagulants like aluminum sulfate and ferric chloride help particles bind together into flocs, which can be more easily removed.
69
What is the difference between temporary and permanent water hardness, and how does each affect wort pH?
Temporary hardness increases mash pH and is removed by boiling. Permanent hardness lowers mash pH and is not removed by boiling.
70
Define water alkalinity and explain how it impacts mash pH during the brewing process.
Water alkalinity measures dissolved carbonates and bicarbonates. High alkalinity increases mash pH, leading to poor saccharification, darker wort, and astringent beer.
71
Why is chlorine used in municipal water supplies, and what potential problems does it pose for brewers?
Chlorine disinfects water by killing pathogens. However, it can cause off-flavors (chlorophenols) in beer and damage brewing equipment if not removed.
72
Explain how storage reservoirs can be seen as an initial water treatment step.
Storage reservoirs blend water sources, dilute contaminants, allow solids to settle, and sunlight helps break down organic material before further treatment.
73
What is Granular Activated Carbon (GAC), and how is it used in raw water treatment?
GAC is a porous material used to adsorb organic compounds. Water passes through GAC vessels, removing taste- and odor-affecting substances.
74
How can the pH of water be adjusted during the raw water treatment process?
Lower pH: Add sulfuric acid or hydrochloric acid. Raise pH: Add sodium hydroxide or sodium carbonate. Increase pH naturally: Aeration removes CO₂, raising pH.
75
Explain the concept of residual alkalinity (RA) and its significance in the brewing process.
RA is the remaining alkalinity after Ca²⁺ and Mg²⁺ react with mash phosphates. A positive RA increases mash pH, while a negative RA lowers mash pH, affecting beer quality.

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