unit 3 lesson 2 Flashcards
1
Q
According to the World Health Organisation, what characterizes safe drinking water?
A
Water that does not represent risk to health over a lifetime of consumption.
2
Q
Name the three primary types of alkalinity.
A
- Bicarbonate
- Carbonate
- Hydroxide
3
Q
What determines water hardness?
A
The level of naturally occurring calcium (Ca2+) and magnesium (Mg2+) compounds.
4
Q
What is the first step in the raw water treatment process?
A
Abstraction.
5
Q
What is the purpose of screening in water treatment?
A
To remove solid objects from the water.
6
Q
What process helps fine suspended material to bind together in water treatment?
A
Coagulation.
7
Q
What is the role of sedimentation in water treatment?
A
To allow large particles to settle out of the water.
8
Q
What is the purpose of filtration in water treatment?
A
To remove suspended material from the water.
9
Q
What is granular activated carbon used for in water treatment?
A
To adsorb organic compounds from the water.
10
Q
What chemicals are commonly used to adjust pH in water treatment?
A
- Sulphuric acid (H2SO4)
- Hydrochloric acid (HCl)
- Sodium hydroxide (NaOH)
- Sodium carbonate (Na2CO3)
11
Q
What is the primary disinfectant used for large municipal water supplies?
A
Chlorine (Cl2).
12
Q
What is the recommended free chlorine residual for effective disinfection according to WHO?
A
0.2 to 0.5 mg/L.
13
Q
What are 3 advantages of chlorine treatment?
A
- Low initial cost
- Low running costs
- Simplicity of handling
- Protection against re-infection
14
Q
What is formed when ammonia reacts with free chlorine in water?
A
Chloramines (NH2Cl)
Chloramines are less effective than chlorine for disinfection but last longer.
15
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 affect water quality and safety.
16
Q
What is the distinction between permanent and temporary water hardness?e
A
- Permanent hardness: cannot be removed by boiling
- Temporary hardness: can be removed by boiling
This distinction is important for water treatment processes.
17
Q
What ions primarily contribute to water hardness?
A
- Calcium cations
- Magnesium cations
These ions are found in various salts that dissolve in water.
18
Q
What happens to temporary hardness when water is boiled?
A
Calcium carbonate (CaCO3) precipitates out
This process reduces the hardness of the water.
19
Q
How does permanent hardness affect mash pH in brewing?
A
It tends to reduce mash pH, primarily caused by the presence of calcium and magnesium sulfates and chlorides
This is due to the interaction of phosphates from the malt with calcium and magnesium ions.
20
Q
What is the formula to calculate total hardness as CaCO3?
A
Total Hardness as CaCO3 = (2.5 x Ca2+) + (4.12 x Mg2+)
This formula converts calcium and magnesium levels to equivalent hardness.
21
Q
What can high levels of water hardness cause in hot water installations?
A
Scaling
Scaling can reduce heat transfer efficiencies in water systems.
22
Q
What affects water alkalinity?
A
The carbonate and bicarbonate concentration
High levels increase mash pH.
23
Q
Who is responsible for the concept of residual alkalinity?
A
Paul Kolbach.
24
Q
What is residual alkalinity (RA)?
A
Any alkalinity (bicarbonate) that remains after calcium and magnesium react with malt phosphate.
25
What is the relationship between darker malts and residual alkalinity?
Darker malts tend to be more acidic.
26
True or False: Higher bicarbonate concentration increases residual alkalinity.
True.
27
What is the initial pH of precipitation and why does it change?
Starts as pure water as water vapor condenses so a pH of 7 but as it falls as rain it absorbs Co2 which forms carbonic acid H2CO3 and the pH drops to 5-6
28
What is the term used for water that is sourced from surface water or groundwater?
The term used is ‘raw water.’
29
What are the benefits of long storage times in reservoirs for water treatment?
Long storage times allow some of the solid contaminants to settle to the bottom, and sunlight begins to break down the organic material.
30
What is abstraction?
Abstraction refers to the process of extracting water from natural sources, such as surface water (rivers, lakes, reservoirs) or groundwater (aquifers). This extracted water is known as raw water. Once abstracted, raw water is either temporarily stored in large, open storage reservoirs or pumped directly into a treatment plant for further processing.
31
Name three chemical coagulants that can be used in the coagulation process.
Aluminium sulphate [Al2(SO4)3], ferric chloride (FeCl3), and ferric sulphate [Fe2(SO4)3].
32
What are the typical dimensions of sedimentation tanks used in water treatment?
Sedimentation tanks are typically rectangular with a length to width ratio of 2:1 to 5:1 and a depth of 1.5-2 meters.
33
What is a ‘floc’ and how is it formed?
r.
A ‘floc’ is a clump of coagulated particles that forms when fine suspended materials bind togethe
34
How is granular activated carbon (GAC) regenerated after it becomes saturated?
The GAC is backwashed with water and then steam is used to regenerate it, enabling the GAC to effectively remove organic compounds again.
35
what metals is oxidized during aeration?
During aeration, iron (Fe2+) and manganese is oxidized into ferric hydroxide [Fe(OH)3], which is then precipitated out and removed by filtration.
36
Apart from Chlorine what is another common way to disinfect water?
UV light
37
What two acid does Chlorine Cl2 form when reacting with water?
Hypochlorous acid (HOCl)
Hydrochloric acid (HCl)
38
What are the sources of Chlorine used for water disinfection?
Liquefied chlorine gas (Cl2)
Sodium hypochlorite solution (NaOCl)
39
What is a more powerful disinfectant? HCl or HOCl?
Hypochlorous acid (HOCl)
40
Why is the pH of water controlled between 5 and 6 during disinfection?
The pH is controlled between 5 and 6 to maximize the formation of hypochlorous acid (HOCl), which is a more effective disinfectant
41
Why is hypochlorous acid (HOCl) preferred over hypochlorite (OCl-) for disinfection?
Hypochlorous acid (HOCl) is preferred because it is a more effective disinfectant.
42
What process must be complete in order to clean GAC and reuse it?
The carbon can become saturated and will thus need to be regenerated. The GAC is backwashed with water and then steam is used to regenerate the GAC. This enables the GAC to effectively remove organic compounds again.
43
Why is ammonia use in water treatment processes?
Ammonia is added to chlorine in water treatment to form chloramines, which produce fewer disinfection byproducts like trihalomethanes (THMs) compared to chlorine alone. Chloramines provide a more stable and long-lasting disinfectant effect, reducing the formation of harmful compounds such as THMs, which are associated with health risks.
44
Define Alkalinity.
The capacity of water to neutralize acids, primarily due to the presence of bicarbonates, carbonates, and hydroxides
## Footnote
Alkalinity is important for maintaining stable pH levels in water.
45
What is Bicarbonate (HCO3-)?
A major component of water alkalinity that can affect the pH of the mash and wort
## Footnote
Bicarbonate plays a crucial role in brewing processes.
46
What role does Calcium (Ca2+) play in water?
A mineral that contributes to water hardness and affects mash pH by interacting with malt phosphates
## Footnote
Calcium is vital for enzyme activity during brewing.
47
What is Carbonate (CO32-)?
An ion that contributes to water alkalinity and temporary hardness
## Footnote
Carbonate levels can influence the taste of the final product in brewing.
48
What are Chloramines (NH2Cl)?
Compounds formed by the reaction of chlorine with ammonia, used for long-lasting disinfection of water
## Footnote
Chloramines are less reactive than chlorine, making them preferable for some water treatments.
49
What is the function of Chlorine (Cl2) in water treatment?
A chemical used for disinfecting water by killing or inactivating pathogenic microorganisms
## Footnote
Chlorine is commonly used in municipal water supplies.
50
Define Clarification in water treatment.
A water treatment process that involves coagulation and sedimentation to remove fine suspended particles
## Footnote
Clarification improves water clarity and quality.
51
What does Disinfection entail?
The process of killing or inactivating pathogenic microorganisms in water, commonly using chlorine or UV light
## Footnote
Disinfection is essential for ensuring water safety.
52
What is Filtration?
The process of removing suspended materials from water using various types of filters, such as sand filters
## Footnote
Filtration is typically one of the last steps in water treatment.
53
What is Granular Activated Carbon (GAC)?
Granular Activated Carbon (GAC) is a highly porous material made from carbon-rich source typically coconut shells. It's used in water purification to adsorb contaminants, improving taste, odor, and safety. GAC is effective at removing organic compounds and chlorine, and it can be regenerated for reuse.
## Footnote
GAC is effective in improving taste and odor of water.
54
What is Ground Water?
Water that has seeped into the ground and is stored in soil and rock layers, often high in minerals
## Footnote
Groundwater is a significant source of drinking water.
55
Define Hardness in water.
The concentration of calcium and magnesium ions in water, which affects its suitability for brewing
## Footnote
Hardness can influence the flavor and quality of brewed beverages.
56
What is an Ion?
An atom or group of atoms with a net positive (cation) or negative (anion) charge
## Footnote
Ions play a crucial role in chemical reactions in water.
57
What is Municipal Water?
Water supplied by local authorities, often treated to meet potable water standards but may require further treatment by brewers
## Footnote
Municipal water quality can vary based on location and treatment processes.
58
What is pH Adjustment?
The process of altering the pH of water to ensure it is neither too acidic nor too alkaline
## Footnote
pH adjustment is necessary for optimal brewing conditions.
59
What is Precipitation?
Water that falls to Earth as rain, snow, or hail, starting as pure water vapor in the clouds
## Footnote
Precipitation is a key component of the water cycle.
60
What is Residual Alkalinity (RA)?
The remaining alkalinity in water after accounting for the neutralizing effects of calcium and magnesium ions
## Footnote
RA is important for understanding water chemistry in brewing.
61
What are Sand Filters?
Filters that use sand beds to remove turbidity, algae, and microorganisms from water
## Footnote
Sand filters are commonly used in both municipal and industrial water treatment.
62
What is Screening in water treatment?
The process of removing large debris from water using metal grills and screens
## Footnote
Screening is often the first step in water treatment.
63
Define Sedimentation.
The process of allowing coagulated particles to settle to the bottom of a tank for removal
## Footnote
Sedimentation is crucial for effective water clarification.
64
What does Total Dissolved Solids (TDS) refer to?
The total concentration of dissolved substances in water, affecting its quality
## Footnote
High TDS levels can indicate poor water quality.
65
What is Total Hardness?
The combined concentration of calcium and magnesium ions in water, expressed as mg/L of CaCO3
## Footnote
Total hardness is a key indicator of water suitability for brewing.
66
Define the Water Cycle.
The continuous movement of water through the environment, including evaporation, condensation, precipitation, and collection
## Footnote
The water cycle is essential for replenishing water supplies.
67
What is Water Treatment?
The process of converting raw water into potable water through various steps, including abstraction, screening, clarification, filtration, aeration, and disinfection
## Footnote
Water treatment is vital for ensuring safe drinking water.
68
What is brewing water also known as?
Brewing liquor or brewing product water.
69
What are the characteristics of safe drinking water according to the WHO?
Microbiologically free of pathogens, colorless, clear, tasteless, odorless, optimal pH close to neutral (7.0), and free from heavy metal ions.
70
What is acid rain, and how is it formed?
Rain with a pH as low as 2.6, formed by picking up sulfate (SO42-), nitrate (NO3-), and other compounds in polluted areas.
71
What are the three primary types of alkalinity?
* Bicarbonate
* Carbonate
* Hydroxide
72
What is the typical pH of groundwater?
Between 6.5 and 8.5.
73
What is the effect of chlorine in brewing water?
It can lead to off-flavors in beer and cause corrosion in stainless steel.
74
What is the first step in raw water treatment?
Screening.
75
What is the purpose of aeration in water treatment?
1. Oxygenation
Aeration introduces air into the water, increasing the oxygen levels. This is essential for promoting the **growth of aerobic bacteria, which help break down organic matte**r in the water1.
2. Removal of Dissolved Gases
Aeration helps to** remove dissolved gases such as carbon dioxide, hydrogen sulfide, and ammonia**. These gases can cause unpleasant odors and taste, and their removal improves the overall quality of the water2.
3. Oxidation of Metals
Aeration **oxidizes soluble iron and manganese, converting them into insoluble forms that can be easily filtered out**. This prevents staining and other issues associated with high levels of these metals in water2.
4. Reduction of Volatile Organic Compounds (VOCs)
Aeration helps to reduce VOCs, which are harmful organic chemicals that can evaporate into the air and cause health issues1.
5. Improved Water Quality
Overall, aeration **improves the clarity, taste, and smell** of water, making it safer and more pleasant for consumption3.To remove volatile organics, carbon dioxide (CO2), and some taste and odorous compounds.
76
What is residual alkalinity (RA)?
The remaining alkalinity after calcium and magnesium have reacted with phosphate compounds.
77
How is RA calculated?
RA = CaCO3 mg/L - [(Ca2+/1.4) - (Mg2+/1.7)]
or
RA = (0.83 x HCO3 mg/L) -[(Ca2+/1.4) - (Mg2+/1.7)]
78
What does a positive RA indicate?
The mash pH will higher as it still has bicarbonate or carbonate remaining
79
How is total hardness expressed/measured in water?
Total hardness is expressed as mg/L of CaCO3.
80
List the range of each level of water hardness?
Very soft
Soft
Medium hard
Hard
Very hard
* 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
81
What is total alkalinity?
Total alkalinity in brewing product water refers to the water's capacity to neutralize acids, primarily due to the presence of bicarbonates, carbonates.
Total alkalinity is typically reported as mg/L as CaCO3
Some water analyses report bicarbonate concentration rather than total alkalinity
82
What is the formula for calculating RA using bicarbonate concentration?
RA = (HCO3- × 0.83) - [(Ca2+/1.4) + (Mg2+/1.7)]
83
True or False: Chlorine is the most widely used disinfectant for large municipal water supplies.
True.
84
What is the ideal pH for chlorine disinfection according to the WHO?
“the pH should preferably be less than 8.0 and the contact time greater than 30 minutes, resulting in a free chorine residual of 0.2 to 0.5 mg/L”.
85
What is water alkalinity affected by?
Carbonate and bicarbonate concentrations
86
What are the effects high alkalinity when mashing?
**Poor extract** from inefficient starch conversion, resulting in lower fermentable sugar levels and potentially affecting the beer's alcohol content.
**Off flavours** - A higher mash pH can extract more tannins from the grain husks, leading to astringent or bitter off-flavors in the beer
**Poor Flavor Stability**
**Poor Colloidal Stability** - Increased alkalinity can cause proteins and polyphenols to remain in suspension, leading to a hazy or cloudy appearance in the final beer
87
Why is understanding water hardness and alkalinity important in brewing?
Essential for brewing high-quality beer
88
What does the right water composition support in brewing?
The brewing process and enhances the final product's flavor and stability
