Transcript Brewing Water - Home Brew Digest

Brewing Water
6 October 2008
A.J. deLange
Burp Education Series
Based on class given 28 April 1996
0
Perspective
• The community (and I) have learned a few things about brewing water
since 1996 (when I last gave this class)
• Then: Slavish attention to reproducing brewing cities’ ion profiles
– A lot of people did a lot of hard work based on bogus data (published ion
profiles)
• Now: Emphasis on getting proper mash pH with brewing liquor that
more or less matches traditional profile
– Recognition of Residual Alkalinity as a powerful tool for evaluating and
comparing brewing water samples
– Tweaking “stylistic ions” to taste (and authenticity).
– Why put it in if you are just going to take it out (e.g. Munich Helles)?
– Often no information whatsoever on type of water required for a particular
style - this is starting to change
• Most modern water supplies are generally good for brewing most
beers.
– Big Exception: Chloramine!!
Note: Red font denotes key concepts - take special note of these
1
Approach
• Water chemistry is intricate and detailed if not complex
• In a couple of hours I can only skim the surface
– There won’t be time to thoroughly explain many of the concepts
– Go back and look at the slides again at leisure
– Some slides are in here with that intention - we won’t do much more than
mention them
• For practical knowledge you must explore further on your own
– Papers on CD
• Most of the bloody details are found in the Cerevesia paper
– Spreadsheet on CD
• This will be your best friend in terms of practical applications.
– Books (see list at end)
– Internet
2
There are Two Aspects to
Brewing Water
• I: Water chemistry has great influence on mash pH
thus great influence on nature of the beer
– Full understanding of this requires knowledge of acidbase equilibrium chemistry, intricate calculations…
• Reviewed in Cerevesia article (on handout CD)
– Fortunately, a simple (to use) Excel spreadsheet (on
handout CD) can handle all of this for you
• You need to know how to use it and what the numbers mean not how to program it
• II: Certain ions influence flavors - just as they do
in any other form of cooking.
– Salt to taste
3
Your Goals
• Understand
– Relationship between beer and water it’s made from
– Fundamentals of chemistry related to brewing water
• Atoms, molecules, ions, moles, equivalents, acids, titration…
– pH, Alkalinity, Residual Alkalinity (RA) and Hardness
• These are the key concepts
• Be able to…
– Read a water report
• Check it for validity (using spreadsheet)
– Treat water to
•
•
•
•
Remove chlorine and chloramine
Reduce bicarbonate (alkalinity) and iron (if you have it)
Control the pH of your mash
Establish an approximation to a desired ion profile
4
Quotations
• “Wine is made by farmers. Beer is made by engineers.” (?)
• “A distinction is frequently drawn in the industry between
the theoretical man who tries to explain everything from a
scientific point of view, and the practical man who relies
on empirical knowledge and experience. A good brewer
should be able to steer a middle course between these two
extremes” - Jean deClerck
• “The third group, the smallest, are the Noonanians, the
triple decoction cultists. Eighteen hour brew days,
elaborate water modifications: you wonder how they stay
married.” - Delano DuGarm
5
Quotations II
• Water contains three ions which influence the pH of wort: bicarbonate,
calcium and magnesium. The bicarbonate ion has a pH raising effect,
the other two lower it. The pH lowering effect of magnesium ions is
only half that of calcium ions. Depending on the ratio of the water’s
content of bicarbonate on the one hand and calcium and magnesium on
the other, the pH raising effects of the bicarbonate is more or less
compensated or balanced. Thus experiment has shown that to balance
1 equivalent of bicarbonate ion 3.5 equivalents of calcium or 7
equivalents of magnesium ion are required. With respect to the pH
raising property of the total alkalinity of the brew water, thus, a
definite part is balanced. The remainder, the residual alkalinity, can
serve as a measure of the pH raising effect of the water.
– Paul Kohlbach, Die Einfluss des Brauwassers auf das pH von Würze und
Bier, Monatsschrift für Brauerei, Berlin, Mai 1953
– Whole paper is on CD. Read it!
6
Topics
• Part 0: Beer and Water
• Part 1: Fundamentals of Chemistry
• Part 2: Carbon Dioxide, Water, Limestone, pH, Hardness,
Alkalinity
• Part 3: Adding Malt Phosphate to the Picture , Residual
Alkalinity
• Part 4: Water reports
• Part 5: Water testing
• Part 6: Water Treatment
• Part 7: Synthesis of water with a given ion profile
• Part 8: Comparison Beer
7
Handout CD Contains…
• A copy of this presentation
• Translation of Paul Kohlbach’s seminal paper (1953)
• A set of slides from a lecture given at DeClerck Chair XI
(Louvaine-la-Neuve, Sept 2004)
• Copy of the paper (based on that lecture) from Cerevesia
29(4) 2004
• Microsoft Excel spreadsheet which implements the
significant brewing water chemistry calculations
• Two part BT article on Alkalinity (unpublished)
• BT article on Chloramine
• New York Times Science article (geology and beer).
• 54 recipes for water of various brewing cities from
common salts and distilled water.
8
Part 0
Overview - Beer and Water
9
Water and Beer Style
• Water is heavy (1 kg/L ~ 8.3 Lbs/gal.)
• Barley, malt and hops can be cost effectively
moved fairly long distances - water can not.
• Therefore, absent ability to treat it, local water
determined what local beer was like
– Soft water: Bohemian Pils
– Hard, bicarbonate Water: Munich Dunkles, London
Ales
• Remove bicarbonate and you can make Helles
– Hard Sulfate Water: Burton Ales
10
The First of the Two Aspects
• Bicarbonate is a base - it’s alkaline
– It raises mash pH ~ malt enzymes become less effective
– It must be neutralized or removed (so pH is kept low)
• Hardness (Ca++, Mg++) plus malt phosphate neutralize it
– Alkalinity (water bicarbonate) not neutralized by water hardness
+ malt phosphate is called Residual Alkalinty
• Acid neutralizes it
– Sulfuric, hydrochloric, lactic, acid in dark malt
– High alkalinity water requires lots of hardness, acid and
or dark malt to neutralize it (and conversely)
• Theme: Contest between alkalinity (bad) and
hardness (good) for control of mash pH.
11
Hardness & Alkalinity for Several Cities
Bad
OK
Good
OK
RA = Alkalinity - (Ca_hardness + Mg_hardness/2)/3.5
12
Part 1
Fundamentals of Chemistry:
Atoms, Molecules, Ions, Acids,
Bases
13
For Further Information…
• We can only skim (rapidly) the surface at the
highest level today
• Nothing here beyond college freshman chemistry
– Should today stimulate your interest, review freshman
chemistry or biochemistry text
• Pay particular attention to ionic equilibrium (law of mass
action), acid/base chemistry, Henderson Hasselbalch equation.
– Read Cerevesia article on CD
14
Atoms
• Smallest particle of elemental matter with nucleus of
positively charged protons and uncharged neutrons…
– … of mass ~1.673E-24 grams (protons and neutrons slightly
different)
• Surrounded by negatively charged electrons
–
–
–
–
–
With mass 0.000911E-24 grams (1/1822 of proton)
Number of electrons equals number of protons
Atom has a net charge of 0.
Electrons group into shells
Most of the elements we’ll deal with like to have 8 electrons in outer shell
• The number of protons (and electrons) determine which
element the atom is
– 1: H, 2: He, 3: Li, 4: Be, 5: B, 6: C 7: N, 8: O 9: F, 10: Ne
• Number of neutrons determines which isotope
– 6 protons + 6 neutrons ~
12C
(normal);
6p + 8n ~
14C
(radioactive)
15
Chemical Symbols
• Each element (atom type) is represented by a symbol
– It’s often pretty obvious which element is meant…
• H ~ Hydrogen C ~ Carbon O ~ Oxygen Ca ~ Calcium Mg
~ Magnesium S ~ Sulfur
– But not always…
• Na ~ Sodium (L. Natrium) K ~ Potassium (L. Kalium) Fe ~
Iron (L. Ferrum) Hg ~ Mercury (L. Hydrargyrum)
• Combined atom symbols represent compounds:
– NaCl ~ Sodium chloride HCl ~ Hydrochloric Acid CaCl2 ~
Calcium chloride H2CO3 ~ Carbonic acid CaCO3 ~ Calcium
Carbonate CaSO4.2H2O Calcium Sulfate with 2 waters of
hydration.
– Subscript indicates number of atoms in molecule
• 1 Molecule of CaCO3 has 1 calcium, 1 Carbon, 3 Oxygen atoms
• Ion (electrically charged atom or molecule) is indicated by
element or compound symbols with charge shown
– Na+ ~ Sodium ion
Ca++ ~ Calcium ion HCO3- ~ Bicarbonate 16
IONS
• Noble gasses Helium, Neon, Argon… have
complete electron shells ~ chemically stable
• Atoms may take on or release electrons to
complete or leave a complete shell
– Sodium ([Ne]+1e-):
Na --> e- + Na+ Sodium Ion
– [Noble gas] represents the electronic structure of that gas
• Giving up 1 electron leaves Neon (10 e-) shell structure
• Could give it to e.g. chlorine…
– Chlorine ([Ne]+7e-): Cl + e- --> Cl- Ion
• ([Ne]+8e- = [Ar])
– Calcium ([Ar]+2e-): Ca --> 2e- + Ca++ Ion
• Take away 2 electrons leaves Argon shell structure
– Hydrogen (1 e-): H --> e- + H+ Hydrogen Ion
• Naked proton (quickly attaches to a water molecule)
17
Molecules
• Atoms can also share (or give) electrons with (to)
other atoms in order to complete shells
– Carbon (C) has 4 electrons in its outer shell: [He]+4e– Hydrogen (H) has 1 electron: 1e– If carbon shares the electrons from each of 4 hydrogen
atoms it completes its outer (valence) shell :
• [He] + 4e- + 4e-(shared from hydrogens) ~ [Ne]
– Each hydrogen shares one of carbon’s electrons
• 1e- + 1e- (shared from carbon) ~ [He]
– CH4 is the gas methane
• Na gives e- to Cl. Na+ attracts Cl- --> NaCl
• Atoms so combined are called molecules the
constituents of compounds.
18
Dissociation
• Some molecules (acids) may release or take on (bases) protons
(hydrogen ions) thus becoming ions themselves
–
–
–
–
Carbonic Acid: H2CO3 --> H+ + HCO3Ammonia (base): NH3 + H+ --> NH4+
Sulfuric Acid: H2SO4 --> H+ + HSO4Hydrochloric Acid: HCl --> H+ + Cl-
Bicarbonate ion
Ammonium ion
Bisulfate ion
Chloride ion
• Ions can do this too and become doubly ionized or un-ionized
– Bicarbonate ion: HCO3- --> H+ + CO3-- Carbonate ion
– Bicarbonate ion: HCO3- + H+ --> + H2CO3 Carbonic acid
• Molecules (or ions) which give up protons are acids in the LowryBrønstead sense (there are other definitions)
• Molecules (or ions) which take up protons are bases in the LowryBrønstead sense.
19
Chemical Equations
• Reactants on left, products on right
• Equation in the sense that numbers of atoms (of each type) and charges
must be equal on each side
• Ca(OH)2 + Ca++ + 2HCO3- --> 2CaCO3 + 2H2O
– This says that 1 molecule of calcium hydroxide (slaked lime) reacts with 1
calcium ion and 2 bicarbonate ions producing 2 molecules of calcium
carbonate (chalk) which precipitates (underbar) and 2 molecules of water
– 2 Calcium, 2 Carbon, 8 Oxygen, 4 Hydrogen, 0 charge on each side
– --> indicates that reaction proceeds from left to right but not in other
direction (many, indeed all, reactions proceed in both directions if
conditions are right but one is sometimes preferred.)
• This reaction is commonly used by brewers to remove bicarbonate
from alkaline water.
• Because it removes calcium, a component of hardness, as well it is
usually thought of as a “water softening” treatment.
20
Measurement of Chemicals
• RE last slide: each molecule of lime will remove 2
bicarbonate ions. How much lime do we need to buy to
process x gallons of water?
• Clearly we need to have some idea of what a molecule
weighs and how many we need.
• Molecules, like atoms and ions, are made up of protons
and neutrons which contribute nearly all the weight as
electron weight is negligible
• One proton weighs 1 Dalton (1 Atomic Mass Unit)
• How many protons weigh one gram?
– Answer: 6.023E+23 called Avogadro’s Number.
– Avogadro’s number of Daltons = 1 gram
– Avogadro’s number of anything (atoms, molecules, ions, electrons,
rutabagas, even furry blind subterranean mammals) is called one
21
mole
Gram Molecular Weights ~
Weight of 1 mole
•
•
•
•
•
•
•
Hydrogen: 1 proton. 1 mole should weigh about 1 gram. Actual GMW
1.00794
Oxygen: 8 protons, 8 neutrons. 1 mole should weigh about 16 grams. Actual
value 15.9994
Calcium: 20 protons, 20 neutrons. 1 mole should weigh about 40 grams.
Actual value 40.078
Ca(OH)2: 38 protons, 38 neutrons. 1 mole should weigh about 74 grams.
Actual GMW 74.093
HCO3-: 31 protons, 30 neutrons. 1 mole should weigh about 61 grams. Actual
GMW 61.03
Thus 1 molecule of Ca(OH)2 reacting with 2 HCO3- ions implies that 6.023E23
(1 mole = 74.093grams) of Ca(OH)2 will react with 12.046E23 (2 moles =
122.06 grams) of HCO3- and so on in that proportion
Example: To decarbonate water with 61 milligrams (mg) of bicarbonate (1
millimole) per liter would require 1/2 mMol of Ca(OH)2 weighing 74.093/2 =
37.046 mg per liter.
22
Equivalent Weight
•
•
•
•
•
•
Sometimes specified weights are based on moles of charge rather than moles
of ions or atoms
Singly charged HCO3-: 31 protons, 30 neutrons. GMW 61.03 means 61.03
grams has a charge of 1 mole of (-) charges. Equivalent weight = 61.03.
Doubly charged Ca++: 20 protons, 20 neutrons. GMW 40.078 means 40.078
grams carries 2 moles of (+) charge. 20.039 grams carries 1 mole. Equivalent
weight = 20.039
Equivalent weight = gram molecular weight divided by charge.
Alkalinity (HCO3-) and hardness (Ca++, Mg++) are often expressed in
milliequivalents per liter (mEq/L sometimes called mVal/L or just mVal).
Sometimes given as 50 times mEq/L - called parts per million as CaCO3
– This is seen a lot. Note: 1 ppm ~ 1 mg/L (as water weighs ~ 1 kg/L)
100mg
1mMol
44mg
1mMol
18mg
1mMol
122mg
2mMol
40mg
1mMol
CaCO3 + CO2 + H20 --> 2HCO3- + Ca++
2mEq
100ppm as
CaCO3
2mEq
100ppm as
CaCO3
23
Example of Calculation
• Being an environmentally conscientious brewer you wish to neutralize
your standard lye cleaning solution (1 pound lye in 5 gal water) before
dumping it down the drain. How much acid is needed?
– Na(OH) + H2O --> Na+ +(OH)- + H2O
• Lye GMW 40: 1 lb = 454 g ~ 454/40 = 11.36 Mol ~ 11.36 Eq (OH)• H+ + (OH)- --> H2O Need 11.36 Eq H+
• Sulfuric Acid MW 98: H2SO4 --> 2H+ + SO4-– 11.36/2 Mol H2SO4 yields 11.36 Eq H+
– 98*11.36/2 = 556 grams ~ 1.23 lbs concentrated sulfuric acid
required.
– 11.36 Mol of Na+ & 11.36/2 Mol SO4-- (11.36/2 Mol Na2SO4, MW
142 ~ 11.36*142/2 = 0.806 kg) go down drain (wrong on CD)
• Hydrochloric Acid MW 36.46: HCl --> H+ + Cl– 38% HCl solution (23 Baume) is 12.29 Normal meaning it contains 12.29
Eq H+ per litre. Therefore need 11.36/12.29 = 0.917 L of 38% HCl
– 664 g NaCl (table salt) goes down drain
• Add acid to solution until pH neutral rather than relying on calculation
24
Another Example Calculation
•
Water tests 3 mg/L available chlorine (from chloramine). How much
potassium metabisulfite (K2S2O5 MW 222.32) is required to treat 20 gal (76 L)
– 2K+ + S2O5-- + 2H2NCl + 3H2O --> 2K+ + 2SO4-- + 2H+ + 2Cl- + 2NH4+
– Each mole of chlorine requires 0.5 mole of bisulfite ion and produces 1 mole of
sulfate, 1 equivalent of hydrogen ions, 1 mole of chloride ions and 1 mole of
ammonium ions.
– 3 mg/L Cl ~ 3/35.45 = 0.0846 mMol/L requiring 0.0423 mMol/L metabisulfite and
producing 0.0846 mMol/L sulfate, hydrogen, chloride and ammonium ions.
– The GMW of potassium metabisulfite is 222.32 mg/mMol so we need 9.4 mg/L or
714 mg total (one lot of Campden tablest we measured weighed 695 mg)
– The hydrogen ions, 0.0846 mEq/L represent a reduction in alkalinity of 50 times
this or 4.2 ppm as CaCO3.
– As each bound chlorine atom is converted to a chloride ion the chloride level will
increase by 3 mg/L
– 0.0846 mMol/L * 96 mg/mMol ~ 8.12 mg/L increase in sulfate (Pils brewers take
note)
– 0.0846 mMol/L*18 mg/mMol ~ 1.5 mg/L increase in ammonium ion (your yeast
will love it)
25
Part 2
Carbon Dioxide, Water &
Limestone; Hardness &
Alkalinity
26
Carbon Dioxide: CO2 MW 44.01
• Spewed by volcanoes
• Taken up by plants -> sugar, starch… oxygen
light C H O + 6O
– 6CO2 + 6H2O ------>
6 12 6
2
• Released by carbohydrate oxidation (including respiration,
fermentation, decay…)
– CnH2nOn + nO2 --> nCO2 + nH2O
• A greenhouse gas
– Though not a very effective one (10% re water vapor)
• Present in the atmosphere to the extent of 0.03% (0.0003Atm ~ 0.3
hPa)
• Absorbed/released by oceans, rivers, lakes
– Sequestered by animals which build shells from it
• Dissolves in water to form carbonic acid which, in turn, dissolves
limestone
– This is the property of significance to brewers (and spelunkers).
27
Water
• Continuous cycle of evaporation, condensation,
precipitation…
• Ultimately comes to us from rain, snow, meltoff..
– Runs over surface of earth into a stream/pond…
• In equilibrium with atmospheric CO2
• Leaches substances from surface organic/inorganic materials with
which it comes in contact
– Or percolates into ground and is withdrawn from well penetrating
aquifer
• In equilibrium with subterranean CO2 (respiring bacteria)
• Typically more acidic (dissolved CO2)
• Dissolves minerals from rock with which it comes in contact
– Limestone caves
• Typically more mineral content than surface water
• Usually clearer, fewer bacteria than surface (well filtered)
• May be in the ground for years.
28
Carbonic Acid MW 62.03
• CO2 dissolves in water to form carbonic acid…
– CO2 + H2O <--> H2CO3*
– * indicates this is both dissolved but not hydrated CO2 and hydrated CO2
– Arrow is two headed. Carbonic acid can decompose into water and CO 2
• … which can give up a proton to form bicarbonate ion…
– H2CO3* <--> H+ + HCO3-
– Ability to give up proton defines H2CO3 as an acid
– In reverse, HCO3- can take up a proton to form H2CO3. This defines a base
• …which can give up its proton to form carbonate…
– HCO3- <--> H+ + CO3--
– The fact that it does so defines bicarbonate as an acid.
– Thus bicarbonate is an acid and a base (it is amphoteric)
• Which it behaves as depends on pH (at brewing pH it is basic)
– In reverse, CO3-- takes up a proton to form HCO3- . CO3-- is a base
• …which can coalesce with calcium ion to precipitate chalk
– CO3-- + Ca++ <--> CaCO3 (only slightly soluble)
29
Calcium Carbonate MW 100.087
• Ca++ + CO3-- --> CaCO3 (lime, chalk, limestone)
– Happens in the bodies of marine animals
– Main source of limestone - sequesters CO2, sends to bottom
– 10% of all sedimentary rock
• Happens when hard bicarbonate water is heated
– Popular method for decarbonating brewing water
• Or when hard bicarbonate water evaporates
– Shower heads
– Stalactites/Stalagmites
• Dissolved by carbonic acid - source of calcium hardness
– CaCO3 + H2O + CO2 --> CaCO3 + H2CO3 --> 2HCO3- + Ca++
– Surface and ground water are hard & alkaline
– Cave formation: underground paCO2 much higher (hence more
carbonic) because of respiring bacteria
30
Law of Mass Action
• In any reaction mA + nB <--> kC + jD
• {C}k{D}j/{A}m{B}n = K, a constant (constant temp.)
– {A} = activity of A
– For a gas {A} is approximately the partial pressure
– For a dissolved substance {A} is approximately the concentration
(moles per liter)
– For a solid {A} = 1
• Define p{A} = - log10{A}
• Then kp{C} + jp{D} - mp{A} - np{B} = pK
• If A + B <--> C (underscore ~ precipitation) then
–
–
–
–
{A}{B} < Ks (solubility product) No precipitation occurs
{A}{B} > Ks supersaturated. Precipitation usually occurs
{A}{B} = Ks saturated. No precipitation
p{A} + p{B} = pKs at saturation
31
Carbonic - Loss of 1st Proton
• H2CO3* <--> H+ + HCO3• {H+}{HCO3-}/{H2CO3*} = K1
• pH + p{HCO3-} - p{H2CO3*} = pK1
– Henderson-Hasselbalch Equation
– p{x} = - log x
– p{H+} = pH is special - more to follow on this
• pH - pK1 = p{H2CO3*}- p{HCO3-}
– rearranged
*
p{H2CO3 } - p{HCO3-}
pH - pK1
• 10
=10
=
{HCO3-} / {H2CO3*} = r1 = ratio bicarbonate to carbonic
– Took antilog of both sides
– Note if pH = pK1 then r1 = 1; {HCO3-} = {H2CO3*}
32
Carbonic - Loss of 2nd Proton
HCO3- <--> H+ + CO3-{H+}{CO3--}/{HCO3-} = K2
pH + p{CO3--} - p{HCO3-} = pK2
pH - pK2 = p{HCO3--}- p{CO3--}
p{HCO3 } - p{CO3--}
pH - pK2
10
=10
= {CO3--} / {HCO3-} = r2 =
ratio carbonate to bicarbonate
• If pH = pK2 then r2 = 1; {CO3--} = {HCO3-}
• Solutions tend to resist pH changes near their pK’s
•
•
•
•
•
– This is called buffering
33
-
--
H2CO3, HCO3 , CO3 Fractions
• If there are x moles of carbonic, there are r1x
moles of bicarbonate and xr1r2 moles of carbonate
for a total of CT = x(1 + r1 + r1r2) =xd
• CT = total carbo
• The fraction which is carbonic is x/xd = 1/d = f1
• The fraction which is bicarbonate is r1 times this =
r1/d = f2
• The fraction which is carbonate is r2 times this or
r1r2d = f3
34
Distribution
of
carbo
species
pH
s
pK1
6.38
pK2
10.35
Alkalinity is defined as the number of mEq of acid required to change the pH
of a sample from its pH at the source (pHs) to pH 4.3
35
Alkalinity
• Definition: the number of mEq of acid required to change
pH of a sample to a reference pH (usually pHr = 4.3)
– Sum of
•
•
•
•
Acid required to change carbonate to carbonic
Acid required to change bicarbonate to carbonic
Acid required to increase {H+} to (1000)10-pHr mEq/L
Acid require to neutralize (OH)-
alk = CT(f1,r - f1,s + f3,s- f3,r) + (1000)10(pHs-pHr) + (1000)10(pKw-pHr-pHs)
•
•
•
•
•
r ~ reference pH, s ~ sample pH, pKw = 14
Units: mEq/L (that’s why the factor of 1000 is there)
CT = total mmol/K carbonic, bicarbonate, carbonate
Equation can be solved for CT if alk, pHr and pHs are known
Thus choice of pHr is somewhat arbitrary
36
Solubility Product
• {Ca++}{CO3--}< Ks Solubility Product
– If {Ca++}{CO3--} = Ks water is called saturated
• p{Ca++}+p{CO3--}< pKs
• Calcium carbonate is not very soluble in water
• To precipitate carbo (and hardness) establish
conditions which violate inequality
–
–
–
–
Increase pH & thus f3 (Drive off CO2 by heat, sparge)
Decrease Ks (raise temperature)
Increase {Ca++} (add gypsum or CaCl2)
Combinations (Ca(OH)2 increases pH and {Ca++})
37
Combine Equations
• Add Eqns for dissolving CO2, CaCO3 saturation, water
dissociation and electric neutrality
pH CO   pP  pK
• CO2 Dissolves:
pH  pHCO  pH CO   pK  pf
• A proton is lost:
• A 2nd proton is lost: pH  pCO  pHCO  pK  3pf

pCa2  pCO32  pKS  8pfm
• CaCO3 Saturation:
pH pOH  pK  pf
• Water dissociates:




0
• The total charge is 0: 2Ca 10  HCO  2CO 10
CO   10
HCO   10


• Define:
r 
r 
HCO 
H CO 

• Substitute into charge
neutrality equation,
• Solve (root
finder) for pH which
satisfies this equation


• Substitute back
2
3
CO2

3
H
2
3
2
3
1

3
m
2
m

W
2

3
pH

3
2
3
2
3
2
3
pH  pK1  pf m
2
1
m
 pKW  pH
pH  pK 2 3 pf m

3
pfm accounts for fact that solutions are not “ideally dilute”. We will ignore this.
38
Why All this Horrible Math?
• It is what allows us to …
– Validate a water analysis
– Calculate alkalinity and estimate the acid required for
proper mash pH
– Synthesize any water ion profile from any starting
water (e.g. salt additions to get Burton water from my
well water)
– Determine whether water is stable (saturated with
respect to CO2 or CaCO3
– Make charts like one on next slide
• It is what is behind the spreadsheet on the CD
39
CO2 Over Water in Equilibrium
with CaCO3
40
Review - Dissolving Limestone
Partial Pressure
of CO2, Atmospheres
.0004
CO 2
Gas Phase
.025
(OH)-
H2O
pKw
pKH
Concentrations,
mg/L
0.84
H2 CO 3
52.5
Liquid Phase
pH 8.3
H+
H2O
pH 7
r 1=70.8
r1 =4.5
pK 1
58.5
r 2=.0065
r2 =.0004
HCO –3 1""
230.8
17.5
Ca +2
80.3
Solid Phase
0.38
CO –3 2
0.095
pK2
pKS
CaCO 3
Alkalinity comes from limestone and the carbonic acid which
Is required to dissolve it.
Calcium hardness comes from dissolved limestone.
41
pH
• Søren Peter Lauritz Sørenson (1868 -1939)
– Worked at Carlsberg Laboratory
– Studied amino acids, proteins enzymes
– Their behaviour (total electric charge) depends on hydrogen ion
concentration (mechanism we’ve been discussing).
– Sought convenient scale for specifying {H+} (1909)
– Called it pondus (L. a weight) hydrogenii i.e. pH = -log10{H+}
– For pure water {H+} = 10-7 Mol/L thus pH = 7
– For .001 N acid {H+} = 10-3 Mol/L thus pH = 3
• pH < 7: Acid, sour, beer, wine, soda (phosphates),
vinegar, lemon, lime (citrus), sauerkraut, sour cream,
kimche
• pH ~ 7: Neutral, water, blood, brine
• pH > 7: Base, bitter, lye, lime (slaked), soda ash
42
Importance of pH in Brewing
• Necessary to calculate carbo species distribution in water
• As pH changes charge distribution on proteins it changes conformation
of enzymes
– Brewing water treatment is done to get enzymes properly
conformed for protein lysis, starch to sugar conversion…
– Happens in range pH 5.2-5.7
• Proper charge distribution on proteins (chains of amino acids) in boil
(iso-electric point~ net charge 0) enhances coagulation
H+
H3N+CRHCOO H
pH 1 Q = 1
H+
H3N+CRHCOO
pH 6 Q = 0
-
H2NCRHCOO
pH 14 Q = -1
-
Charge (Q) shown for simplest amino acid, Glycine (R = H)
Note: For some amino acids (Arginine, Lysine, Tyrosine….) R may
be ionizeable in which case other charge values are possible
43
Importance of pH II
• Tanins not extracted from barley husks if sparge pH < 6
• Yeast produce acid to kill competing organisms
– Thus pH drop is first sign of healthy fermentation
• pH has an effect on stability of colloids in finished beer.
• pH modulates formation of melanoidins
• IOW, each part of the brewing process proceeds best in a
range of pH (and temperature)
– XI DeClerck Chair: 3 Days of lectures on “pH Paradox” devoted to
this subject
• Advanced brewer feels as helpless without his pH meter as
he does without his thermometer.
44
pH Measurement
• Originally with dye which changes color at particular pH
– “Litmus Test” from a lichen (red < 7, blue >7)
– Phenolpthalein, bromcresol red, methyl orange (4.3) …
• Electronically: potential developed across specially prepared (delicate)
glass bulb dependent on pH difference between inside and out
– Potential measured between electrode inside bulb and reference junction
electrically connected to solution being measured (outside bulb)
– Very feeble current. Extremely high impedance amplifier required
– 57 millivolt change per unit pH change
• Depends on temperature - temperature compensation essential
• Note: pH also changes with temperature (because pK’s do). This is a separate
effect
• Special field effect transistors (ISFET)
– Much more durable, store dry
• Modern meters more dependable, last longer, less expensive, feature
rich (ATC, auto buffer recognition) but still not for the casual user.
• Must be calibrated frequently with buffers of known pH
45
Part III
Adding Phosphate, Residual
Alkalinity
46
Phosphoric Acid Chemistry
• Same as carbonic except
– The oxide is a solid: P2O5 + 3H2O --> 2H3PO4
• Compare: CO2 + H2O --> H2CO3
• General reaction for oxoacids
– Includes carbonic, phosphoric, nitric, sulfuric
– Three protons:
• H3PO4 --> H+ + H2PO4- --> 2H+ + HPO4-- --> 3H+ + PO4--• Three (not the same as carbonic) pK’s (2.12, 7.21, 12.67), three r’s, three f’s.
• Calcium phosphate is very insoluble
– The smallest amount of phosphate will pull out lots of calcium
– This is why trisodium phosphate was used as water softener
• 3Ca++ + 2Na3PO4 ---> Ca3(PO4)2 + 6Na+
– And why malt phosphate lowers pH of hard water
• Net reaction releases protons (hydrogen ions) - later slide
47
Phytic Acid from Malt
48
Malt Phosphate
• Up to 2% of malt weight is phosphate
– In the form of phytin, salt of myoinositol hexaphosphate
• Enzyme phytase breaks down phytin releasing inorganic phosphate
(H2PO4-, HPO4--) and B vitamin myoinositol (good for yeast)
– Phytase survives only mild kilning i.e. active in pale base malts only
• Phosphate coalesces with any calcium in water, precipitates and
releases protons which lower mash pH.
• Paul Kohlbach observed that 3.5 mEq of Ca++ or 7 mEq Mg++
“neutralize” 1 mEq alkalinity
– Neutralize here means that the pH of a mash with all alkalinity neutralized
has same pH as a distilled water mash (~ 5.7)
– Defined Residual Alkalinity: RA = alk. -({Ca++} + {Mg++}/2)/3.5
• Alkalinity, hardnesses and residual alkalinity all in units of either mEq/L or
ppm as CaCO3.
– Also noted 0.085 pH shift for each mEq/L (50 ppm) of RA
49
Residual Alkalinity Chart
• Residual Alkalinity: RA = alk. -({Ca++} + {Mg++}/2)/3.5
• Define Hard_eff = -({Ca++} + {Mg++}/2)
– Effective hardness equals calcium hardness plus half magnesium hardness
• Then RA = alk. - Hard_eff/3.5
• Solve for alk: alk = RA + Hard_eff/3.5
• Plotting alk vs. Hard_eff for a given RA gives a straight line which
crosses the alk axis at RA and has slope 1/3.5
• This is the chart from earlier in the presentation
• RA values in increments of 50 ppm as CaCO3 corresponding to pH
shift increments of 0.085
• Above heavy line (RA = 0) pH will be higher than distilled water
mash, below it, pH will be higher
• RA < 50 generally OK (dotted line)
50
RA Chart
51
Use of Chart - Example
• Edinburg (Edn2): Alk 180, Hard_eff 340, RA 85,
pH ~ 5.89 is too high
• Reduce alkalinity by 180 - 100 = 80 to get to RA ~
0 and pH ~5.75
– Add 80/50 = 1.6 mEq/L acid (e.g. HCl, H2SO4)
– Decarbonate water. Can get to approximately 50 ppm
as CaCO3, RA ~ 35, pH 5.69
• Could also get to this RA by adding (180 -50)/50 = 2.6 mEq/L
acid
• Add (620 - 340)/50 = 5.6 mEq/L hardness
– 5.6 mEq/L Ca++ ~ 2.8 mMol/L CaSO4.2H20 ~ 482
mg/L gypsum
52
Carbo + Phosphate System
10Ca+2+12HCO3- + 6H2PO4- + 2H2O -> Ca10(PO4)6(OH)2 + 12CO2+ 2H+ +12H2O
CO 2
H2O
% Total CO 3
@pH 5.5
@pH 7.0
87.6%
H 2 CO 3
18.3%
r1 =0.14
r 1 =4.46
12.4%
r2 =1.4E-5
81.7%
r2 =4.5E-4
HCO 3–""1
H+
.0002%
CO 3– 2
.04%
p KsC
H+
CaCO 3
H+
p Kw
H+
% Total P O4
@pH 5.5
@pH 7.0
r1 =2398
98.0%
H2 P O4 – 1
r1 =75857
61.3%
(OH)-
Ca + 2
H+
H+
.04%
H3 P O4
.0008%
p Kw
H2O
r 2=.02
1.95%
HP O4 – 2
38.7%
r 2=0.631
r3 =1.1E-7
< .00001%
P O4 – 3
r3 =3.6E-6 .001%
(OH)p KsP
Ca + 2
Ca 10 P O4 6  OH

2
53
Demonstration
• Prepare phosphate buffer from 40 mMol/L KH2PO4
• Add Na2HPO4 to pH 5.92
– Phosphate buffers very commonly used to control pH in laboratory
• Simulates phosphate distribution in distilled water mash
• Add strong CaCl2 solution drop by drop and observe pH
• pH falls gradually at first, then as precipitate (hydroxyl
apatite) forms, more rapidly
• This is the mechanism by which hard water produces acid
to neutralize alkalinity
– There is no alkalinity here (buffer made with distilled water)
– Were alkalinity present, pH drop would no be so dramatic as some
of the H+ released would go to neutralize it.
54
Part IV
Water Reports
55
Water Report Key Parameters
1st Aspect
• Alkalinity
– Measure of acid required to lower sample pH to 4.3 ~ buffering
capacity of water
– Indicator of amount of acid (from any source) required to establish
proper mash pH (5.2-5.6)
– Measure of bicarbonate content
• Hardness
– Measure of amount of calcium and magnesium in sample.
• Mg++ and Ca++ should be measured and reported separately
– Indicator of extent to which water is capable of offsetting it’s
alkalinity (reaction with malt phosphate)
• pH
– Permits calculation of ion balance (quality check on report)
– Permits calculation of amount of bicarbonate from alkalinity
– Otherwise, not really that important
56
Water Report Key Parameters
2nd Aspect
• Sulfate
– Large effect on the way hops are perceived
• High value for assertive, dry hop flavor
• Low (15mg/L or less) for beers using a lot of noble hops
• Sodium
– Leads to salty taste in high concentrations
• Chloride
– Leads to salty taste in high concentration, “pasty” in very high >300mg/L
– Lends round, sweet quality in modest amounts
• Iron
– The less the better - tinny, “inky”, metalic taste
• For Brewing, < 0.1 mg/L ; EPA secondary limit < 0.3mg/L
• Copper
– Metalic taste. May indicate pipe corosion
• Need a small amount. Yeast enzyme co factor
• Chlorine and, in particular, Chloramine
– Chloramine forms ppb detectable chlorphenolics (plastic taste)
57
Calcium
• Most important brewing ion?
• From dissolved limestone, gypsum
• Important enzyme co-factor
– Protects a-amylase from heat
– Stimulates proteolytic and amylitic enzymes
– Reaction with phytin lowers mash pH
•
•
•
•
Favors rapid, bright runoff
Facilitates break formation
Improves yeast flocculation
Precipitates oxalate in beer (enhanced clarity)
58
Magnesium
• Part of hardness - half as effective as Calcium in RA
reduction (mEq for mEq).
• Laxative above 120 ppm esp. with SO4-• Sour/bitter quality at > 30 ppm
– Hence remove if above this level by split treatment (to be covered)
– Not a problem with local (DC area) water
• There are claims that it lowers cardiac mortality
59
Sources of Water Reports
•
Your supplier (municipality, water company…)
– Go to its website, call or visit the office
– You are likely to get a lot of promotional material about DBP rule,
cryptosporidium, industrial contaminants etc.
– Persist until you get an inorganic report including alkalinity and hardness
• Tell them that you are a brewer and this is what you need
• In earlier days some suppliers were reluctant to release information. Rare
today
•
•
•
– May not be timely e.g. summary for 2008 may not publish until 2009
Test results from commercial lab (individual or community well owners)
– Make sure you get an inorganic analysis
• Organic and microbiological tests important too but not for your
brewing needs
– Ask other brewers (Ward Labs seems good)
– Look in yellow pages/on web
Results from tests you do yourself
Profiles published in books, articles, papers, …
60
61
April: 50*32.5/20 (Ca) + 50*8.2/12.15 (Mg) = 80 + 33.7 = 113.7 total hardness. Compare
to April total and calcium hardness numbers on previous slide. Could be different methods
(e.g. AAS) samples taken on different days etc.
62
63
Imbal =100*(1.4-1.1)/(1.4+1.1)=12%
64
Water Report QA Check
• Any water report should be checked for internal
consistency
– Especially ones done by yourself or a lab
– Lab often includes QA check as part of its report
• Check based on electrical neutrality i.e. sum of
charges on anions should equal sum on cations.
– As relative numbers of carbonic (0), bicarbonate(-1)
and carbonate(-2) depend on pH calculation gets a bit
nettlesome
• Must calculate CT, r’s, f’s
– Spreadsheet on CD takes care of all this for you
• Full instructions for use on 2nd sheet.
65
Data entry in clear cells.
Calculated results in
colored cells
Result in red cell should
be < 10%
A vailable Wat er
pH
Temp + f or C, - f or F
T e mp K
pK 1
pK 2
pK w
A
r1
r2
f1 = 1 /d
f2
f3
f1 + f2 + f3
N o c arb al k al init y
A lk, + as CaCO3, - mEq/L
Ca, + as CaCO3, - as mg/L
Mg, + as CaCO 3 - as mg/L
A lk , mE q/K
2 8 .4 5 6 8 <-- mg/L Ca mEq/L-->
1 1 .6 6 6 4 <-- mg/L Mg mEq/L-->
R ough C arbo
R ough C arboni c
R ough Bi c arbonat e
R ough C arbonat e
T otal C arbo, mM ol/L
H2CO3, mg/L
H2CO3,mg/L
CO3--,mg/L
H+
(O H )Sulf at e. mg/L
Chloride, mg/L
Nit rat e, mg/L
Nit rit e, mg/L
Sodium, mg/L
Potassium, mg/L
Fe(II), mg/L
Fe(III), mg/L
Free A mmonia, mg/L
6 .0 0
2 0 .0
2 9 3 .2 0
6 .3 8
1 0 .3 8
1 4 .1 6
0 .7 1 4
0 .4 2
0 .0 0
0 .7 1
0 .2 9
0 .0 0 0 0
1 .0 0
0 .0 4 9 1
4 .3 0 0 End Point pH
2 0 .0 T e mp, C
2 9 3 .2 0
6 .3 8
1 0 .3 8
1 4 .1 6
0 .0 1
0 .0 0
0 .9 9 B ic arb. @ pH a
[H +] @ pH a D iffe renc e
0 .0 1
0 .0 3 4
0 .0 5 0
- 0 .0 1 6
0 .0 0 0 0
1 .0 0
6 2 .0 0
7 1 .0 0
4 8 .0 0
1 .2 4 0 0 0 G ram
1 .4 2
0 .9 6
4 .1 7 5 3 5
1 2 9 .8 1
7 4 .7 3
0 .0 1
4 .1 6 0 5 4
1 2 9 .3 5
74.50
0.00
0.00
0.00
2 0 .4 0
7 .0 0
0 .0 0
0 .0 0
0 .0 0
0 .0 0
0 .0 0
0 .0 0
0 .0 0
E q. Wt C ati ons
2 0 .0 4
1 2 .1 5
0 .0 0 0
6 1 .0 3
3 0 .0 2
1 .2 2 1
0 .0 0 0
0 .0 0 1
Total Hardness, as CaCO3
Residual A lkalinit y
Residual A lkalinit y
pH Shif t RE Dist illed Wat er
Ionic Strengt h, non carbo
Ionic Strengt h, carbo
Total Ionic St rengt h
pfm
0 .0 0 0
0 .4 2 5
0 .1 9 7
0 .0 0 0
0 .0 0 0
4 8 .0 4
3 5 .4 5
6 2 .0 0
4 7 .0 0
2 2 .9 9
3 9 .1 0
2 7 .9 2
1 8 .6 2
0 .0 0 0
0 .0 0 0
0 .0 0 0
0 .0 0 0
3 2 .0 1
0 .0 0 0
Charges
Imbal
Imbal %
A lkalinit y
Ca Hardness, as CaCO3
Mg Hardness, as CaCO3
A nions
1 .4 2 0
0 .9 6 0
2.381
0.538
12.74%
2 3 1 7 3 .1 7 4
1.843
62.00
71.00
48.00
119.00
34.86 ppm as C aC O 3
0.70 mE q/L
0.06
2 .9 0
0 .6 1 2 2 4
3 .5 2
0 .0 3 9 2
66
0 .0 3 5 8 9 1 0pfm, no c arbo
Full set of measurements from
6341 Georgetown Pike well
30 Oct 2008
67
Worksheet for 30 Oct 08
Analysis
68
Part V
Testing Water
69
Why Discuss Testing
• Test principals build on many of the things you have learned and most
important test (alkalinity) mimics what happens in mash
– Acid is added causing pH to drop
– This is why alkalinity is a useful measure
• Explanation of how test is done will enhance your understanding of
what the parameter means
• You may wish to do some testing yourself
– Only way to get a feel for extent of temporal variation in your supply
• Most tests relatively easily carried out with kits
– Get these from www.hach.com or aquarium supply company
– These things are getting expensive!
70
pH (Water Analysis Perspective)
• Need to measure/detect “end point” pH in
alkalinity titration
– This can be done with indicator dyes but woe betide the
color blind (your instructor)
– Electronic means more accurate, even for non
Daltonians
– Electronic meters now more reliable, inexpensive,
durable, feature laden than before
• But be kind to your pH meter. Keep it clean and wet. Don’t
stick it into hot wort or mash!
71
pH Meter
• Voltage E = E0 + (RT/F)ln{H+} is developed across special
glass membrane
– E0 is voltage developed when {H+} = 1
– R (Bolzman’s) and F (Faraday’s) are constants
– T is temperature (Kelvins)
• E = E0 + 2.303(RT/F)log{H+} = E0 - S*pH
• You (or the meter), must know E0 and S in order to
determine pH = (E0 –E)/S
• This is where standard buffers come in
– Placing the meter in 2 solutions of known pH and at known
temperature allows meter to calculate S and E0
• Thereafter meter can adjust readings for temperature response of electrode
(ATC)
• But not, e.g. shift in wort pH from kettle to room temperature!
72
Alkalinity
alk = CT(f1,a- f1,i+ f3,i- f3,a) - 1000(10-pHa -10-pHi +10pHi-pKw-10pHa-pKw)
•
•
Defined as the number of mEq/L of acid required to lower pH of water sample
from its initial value, pHi, to a reference pH, pHa
pHa is part of definition of alkalinity and is usually 4.3 in brewing
– May be based on equivalence: CTf2,a ≈ (1000)10-pHa
– Analyst should report pHa. If he didn’t use 4.3
– Important because you will solve for CT in report quality checking, synthesis
•
•
•
•
•
•
Units of mEq/L (hence factor of 1000). Multiply by 50 for ppm as CaCO3.
CT = total millimoles/L carbonic, bicarbonate, carbonate in sample
f s subscripted i refer to fractions at pHi
f s subscripted a refer to fractions at pHa
Kw is dissociation constant of water (pKw = 14 @ 20°C)
Equals sum of acid required to
– Convert initial fractions to fractions (mostly carbonic) at pHa
– Increase hydrogen ion content to 10-pHa
– Decrease (by neutralizing to H2O) hydroxyl ion concentration to 10pHa-pKw
73
Alkalinity II
- Definition: The number of mEq of acid which must be added to a
liter of water to bring pH to 4.3 (IOW, to convert most carbonate and
bicarbonate to carbonic). Multiply by 50 for ppm as CaCO3.
- Measured by titration (addition of small amounts of acid
until pH 4.3 is reached and reporting total used)
- A rough indication of the amount of acid needed in the mash per L water
Example sample pHi
Where you’d
Like to be in
Mash tun
Where you go
during titration
74
Alkalinity - Procedure
• Add an indicator (e.g. methyl orange or bromcresol greenmethyl red) or a pH electrode to 100 mL sample
• Using a buret (conventional, digital, automatic,
eyedropper, syringe…) add 0.1N (.1 mEq/L) acid (usually
sulfuric) to sample until indicator turns color or pH 4.3 is
reached
– Other endpoint pH values can be used
• Report total number of mL acid used and endpoint pH
– Multiply by 50 for ppm as CaCO3.
• Kits available: Hach AL-AP $36.79 (100 tests)
– Phenolphthalein (8.3) and Bromcresol Green-Methyl Red (4.3)
indicators, sulfuric acid, measuring tube and bottle
75
Alkalinity Titration using pH Meter
(Indicator also present)
Sulfuric acid cartridge
Digital Titrator:
Plunger, lead screw,
counter
Dip Tube
pH electrode
pH Meter
76
++
++
Total Hardness (Ca + Mg )
• Certain dyes (e.g. Eriochrome Black) are one color (red) in
the presence of Ca++ or Mg++ and another color (blue) in
their absence.
• Add such a dye to 100 mL of sample with buffer to set pH
for sharp end point
• Titrate with a standardized strength chelating agent
(EDTA) until the sample changes from red to blue.
• Report the number of mL chelant used (it has been
calibrated to a convenient number of mEq or ppm or grains
or dH (German degrees) etc. hardness per mL)
• This gives the total hardness (sum Ca + Mg)
• Kits available: Hach HA-71A $48.25 (100 tests)
– Test tube/bottle, EDTA, Indicator, buffer, 20 ppm res.
77
Calcium Hardness
• Remove Mg++ from water by raising pH (add suitable
buffer)
– Mg++ + 2(OH)- --> Mg(OH)2 (insoluble gel)
• Add dye and titrate with EDTA as before. This gives
calcium hardness
• Subtract from total hardness to get magnesium hardness
• Kits available: Hach HA-4P Total and Calcium Hardness
$65.05 (100 tests) 20 ppm as CaCO3 resolution
– Test tube and bottle, 2 indicators, 2 buffers, EDTA
– Doubling amount of sample halves resolution (to 10 ppm) and
halves number of tests per kit (to 50).
78
Hardness - Colorimetric
•
•
•
•
•
•
Add dye to sample
Divide into three portions
Chelate Ca++ and Mg++ from first (excess EDTA)
Chelate Ca++ only from second (excess EGTA)
Do nothing to third.
Zero spectrophotometer with first - read second. Color
depth difference is proportional to Mg++
• Zero specrophotometer with second - read third. Color
difference is porportional to Ca++
• Add the two values for total hardness.
• No simple kits available - requires photometer or
spectrophotometer.
79
Chloride
• Titration (kits available)
– Diphenyl Carbazone forms a light pink complex with Hg++
(mercuric) ions
– Add DPC to sample, titrate with calibrated mercuric nitrate.
– Precipitate of HgCl2 forms.
– When all Cl- has precipitated any additional Hg++ forms colored
complex with diphenyl carbazone.
– Amount of Hg(NO3)2 used to obtain color is proportional to
amount of chloride in sample
• Colorimetry (uses photometer)
– Add Mercuric Thiocyanate
• Hg(SCN)2 + Cl- ---> HgCl2 + 2SCN-
– Add ferric ion solution
• 3SCN- + Fe+++ ---> Fe(SCN)3 (red orange)
– Measure depth of color formed with photometer.
• Note: Nasty mercury salts used in both these - Hg waste
80
Sulfate
• Barium sulfate is insoluble, Barium chloride is
soluble.
• Add barium chloride to sample. Barium coalesces
with sulfate to form insoluble BaSO4
– Special agents in test reagent keep this in suspension
• Read turbidity in turbidimeter or
spectrophotometer calibrated with standard
solutions.
• No kits available - requires turbidimeter or
photometer.
81
Sodium
• No practical chemical method
• Atomic Absorption/Atomic Emission Spectrophotometry
– Sample is vaporized into flame. Optical absorption (or emission) at 589.6
nm is measured.
• Ion Selective Electrode (ISE)
– Similar to pH electrode except that its glass responds to log{Na+} rather
than log{H+}
– Expensive (hundreds of $)
– Electrical response to calibrated standards is recorded (similar to pH).
– Electrical response to sample is recorded
• Electrode is very slow to respond (especially at low concentrations) so
automatic (e.g. strip chart) recording is preferred
– Sample response is interpolated into calibration “curve”
• Some meters have the math built in
82
Sodium - Multiple Additions
• mV = U1 + Unlog{Na+}
– U1 = response to 1 mg/L (unknown)
– Un = response change per decade (only approximately known)
– {Na+} = sample sodium concentration (what we want to know)
• Place electrode in known volume, v0, of sample and record response
• Add “spikes” i.e. known volumes v1, v2… mL of sodium standard
solution of known strength S mg/mL. Then…
mV0 = Unlog(v0{Na+}0) + U1
mV1 = Unlog(v0 {Na+}0 + S(v1)/(v0 + v1)) + U1
mV2 = Unlog(v0 {Na+}0 + S(v1 + v2 )/(v0 + v1 + v2 )) + U1
3 measurements are sufficient (though more are better) to allow estimation of
{Na+}0, Un, and U1
• Math is not basic (iterative non linear mmse estimation) but easily handled in
a laptop
•
•
•
•
– Excel Solver can do it!
83
Sodium ISE Recording Example
25
-95
-100
Sodium Electrode Response
50 mL Sample; 1 ml Spikes of 100 mg/mL
Response
Temperature
Exponential fit to response
24
-110
-110.99 ± 0.028 mV
23
...to here
-115
-111.6mV
Temperature, °C
Electrode Response, mV
-105
-120
22
Fit from here...
-125
-130
21
8:30 AM
9/23/08
9:00 AM
9:30 AM
10:00 AM
Time
84
Analysis of Assymptotic mV Readings from
Previous Slide
Slope = 48.4336, Intercept = -148.0979 mV, Concentration = 5.8632
± 0.0255 mg/L; rmse = 0.1015 mV after 88 iterations. Un DOP =
4.74 mV/decade/mV; U0 DOP = 7.57 mV/mV; Concentration DOP =
4.48 mg/L/mV
Electrode Response, mV
-98
Calculat ed and Measured Electrode Response
Mesured Response
Calculat ed Response based on
Est imated Paramet ers
0.15
Measured - Calculated, mV
-96
-100
-102
-104
-106
Dif f erences Bet ween Calculat ed Electrode
Response Based on MMSE Estimat es of
Slope, intercept and I nitial Concentrat ion
and Measured Response
0.10
0.05
-108
0.00
-110
6
7
8
9
10
Calculat ed Concentration, mg/L
50
51
52
Tot al Volum e, mL
53
54
85
Chlorine/Chloramine
• N,N-diethyl-p-phenylenediamine (DPD) added to sample
• Magenta Würster Dye formed if free chlorine is present
• Depth of color measured on photometer or judged relative
to printed color patches, color wheels etc.
• Where chloramine is present it is converted to free chlorine
first - total reading
• Difference RE free chlorine measurement is chloramine
• Kit: Hach CN-66 $45.29 (50 tests total; 50 free)- 0.1 ppm
resolution
– DPD, color wheel, 2 test tubes, test fixture.
86
Other Ions
• There are tests for dozens of other ions
– Fe(II), Fe(III), Cu, Mn, Zn, NO2, NO3, K, Al, SiO2, NH3… all
based on similar principals
– Kits are available for many (www.hach.com)
• Most of these are not important in brewing unless well in
excess of typical values
– i.e. in excess of EPA secondary limits
• Water tastes bad.
– If in excess of primary limit, don’t drink it or brew with it
– Fe, Cu, Zn in excess may indicate corrosion
• Zn in particular may indicate leaching from brass in well fittings with
potential that lead is being extracted as well
– Brass containing lead now prohibited in wells
87
Summary of Measurement Techniques
• Titration
– Addition of reagent of calibrated strength until an end point (color
change, particular pH…) is reached
• Color development; color depth measurement
– By visual comparison to printed chart, color wheel etc.
– By use of photometer of spectrophotometer
• Gravimetry
– A precipitate is formed, separated and weighed
– A precipitate is formed and kept in suspension. Its ability to scatter
light is mesured by a nephelometer or spectrophotometer
• Electrochemistry
– An electrode which responds to the concentration of a particular
species of ion is placed in the sample.
88
Practical Considerations
• Only the simplest tests (alkalinity, hardness,
chorine) can be done without a lot of trouble and
expense
– Of limited but sufficient accuracy for brewing
• More accurate measurements, as with pH,
require calibration with standards
– Chemistries age. Old chemistries can be used past
expiration dates but standards must be employed
– Much more involved than tolerability unless this is part
of the hobby (or commercial operation)
89
Part VII
Synthesizing Water With Desired
Profile
90
Where Do I Get Profiles?
• From textbooks, friends, articles, the internet, the
ones on the handout CD ROM
– Caution - not all profiles are physically realizeable.
• Reporting, measurement, interpretation errors
• Reporting of average values
– Simple check: add up all ion concentrations, specify a
pH and calculate net electronic charge
• Must be close to 0 (imbalance of a few %)
• Easily done with spreadsheet on CD ROM
• Same as for evaluating quality of water reports
• You can’t get a good approximation to an
unrealizeable profile!
91
Target Profile:
Burton on Trent
Target Wat er
pH
Temp + f or C, - f or F
T e mp K
pK 1
pK 2
pK w
A
r1
r2
f1 = 1 /d
f2
f3
f1 + f2 + f3
N o c arb al k al init y
A lk, + as CaCO3, - mEq/L
Ca, + as CaCO3, - as mg/L
Mg, + as CaCO3 - as mg/L
A lk , mE q/K
3 5 2 <-- mg/L Ca mEq/L-->
2 4 <-- mg/L Mg mEq/L-->
R ough C arbo
R ough C arboni c
R ough Bi c arbonat e
R ough C arbonat e
T otal C arbo, mg/L
H2CO3, mg/L
HCO3-,mg/L
CO3--,mg/L
H+
(O H )Sulf at e. mg/L
Chloride, mg/L
Nit rat e, mg/L
Nit rit e, mg/L
Sodium, mg/L
Potassium, mg/L
Fe(II), mg/L
Fe(III), mg/L
Free A mmonia, mg/L
6 .6 0
2 0 .0
2 9 3 .2 0
6 .3 8
1 0 .3 8
1 4 .1 6
0 .7 1 4
1 .6 5
0 .0 0
0 .3 8
0 .6 2
0 .0 0
1 .0 0
0 .0 4 9 9
4 .3 0 0 End Point pH
2 0 .0 T e mp, C
2 9 3 .2 0
6 .3 8
1 0 .3 8
1 4 .1 6
0 .0 1
0 .0 0
0 .9 9 B ic arb. @ pH a[H +] @ pH a D iffe renc e
0 .0 1
0 .0 4 8
0 .0 5 0
- 0 .0 0 2
0 .0 0
1 .0 0
1 8 2 .3 0
- 3 5 2.0 0
- 2 4 .0 0
3 .6 5 G ram
1 7 .5 6
1 .9 7
5 .8 4 7 1 7
9 6 .9 6
2 2 2 .2 2
0 .0 6
5 .8 2 4 2 0
9 6 .5 8
221.45
0.04
0.00
0.00
8 2 0 .0 0
1 6 .0 0
1 8 .0 0
0 .0 0
4 4 .0 0
0 .0 0
0 .0 0
0 .0 0
0 .0 0
E q. Wt C ati ons
A nions
2 0 .0 4
1 7 .5 6 5
1 2 .1 5
1 .9 7 5
0 .0 0 0
6 1 .0 3
3 0 .0 2
3 .6 2 9 Bicarbonate
0 .0 0 1
0 .0 0 0
4 8 .0 4
3 5 .4 5
6 2 .0 0
4 7 .0 0
2 2 .9 9
3 9 .1 0
2 7 .9 2
1 8 .6 2
1 .9 1 4
0 .0 0 0
0 .0 0 0
0 .0 0 0
3 2 .0 1
0 .0 0 0
Charges
Imbal
Imbal %
A lkalinit y
Ca Hardness, as CaCO3
Mg Hardness, as CaCO3
182.30
878.24
98.75
Total Hardness, as CaCO3
976.99
Residual A lkalinit y
Residual A lkalinit y
pH Shif t RE Dist illed Wat er
-82.73 ppm as C aC O 3
-1.65 mE q/L
-0.14
Ionic Strengt h
pfm
Ca
Mg
3 9 .7 6
3 7 .9 4
0 .1 1 0 2
0 .1 0 8 3
21.454
0.012
0.03%
0 .0 0 0
1 7 .0 7 1 Sulf at e
0 .4 5 1 Chloride
0 .2 9 0 Nit rat e
0 .0 0 0 Nit rit e
Sodium
Potassium
Fe(II), mg/L
Fe(III), mg/L
2 3 1 7 3 .1 7 4
21.442
92
Base Water
• Deionized (DI) water (distilled, ion exchanged but
not by home water softener!) represents “blank
piece of paper”
– RO water is a decent approximation to DI
• Other water: can increase an ion concentration
easily but not decrease it
– Dilution with DI/RO water
– Bicarbonate can be removed to some extent
• Takes calcium and magnesium with it.
• Modern municipal supplies generally represent a
decent starting point
93
Source Water
McLean Well
A vailable Wat er
pH
Temp + f or C, - f or F
T e mp K
pK 1
pK 2
pK w
A
r1
r2
f1 = 1 /d
f2
f3
f1 + f2 + f3
N o c arb al k al init y
A lk, + as CaCO3, - mEq/L
Ca, + as CaCO3, - as mg/L
Mg, + as CaCO3 - as mg/L
A lk , mE q/K
<-- mg/L Ca mEq/L-->
<-- mg/L Mg mEq/L-->
R ough C arbo
R ough C arboni c
R ough Bi c arbonat e
R ough C arbonat e
T otal C arbo, mM ol/L
H2CO3, mg/L
HCO3-,mg/L
CO3--,mg/L
H+
(O H )Sulf at e. mg/L
Chloride, mg/L
Nit rat e, mg/L
Nit rit e, mg/L
Sodium, mg/L
Potassium, mg/L
Fe(II), mg/L
Fe(III), mg/L
Free A mmonia, mg/L
6 .0 0
2 0 .0
2 9 3 .2 0
6 .3 8
1 0 .3 8
1 4 .1 6
0 .7 1 4
0 .4 2
0 .0 0
0 .7 1
0 .2 9
0 .0 0 0 0
1 .0 0
0 .0 4 9 1
4 .3 0 0 End Point pH
2 0 .0 T e mp, C
2 9 3 .2 0
6 .3 8
1 0 .3 8
1 4 .1 6
0 .0 1
0 .0 0
0 .9 9 B ic arb. @ pH a
[H +] @ pH a D iffe renc e
0 .0 1
0 .0 3 4
0 .0 5 0
- 0 .0 1 6
0 .0 0 0 0
1 .0 0
6 2 .0 0
7 1 .0 0
4 8 .0 0
1 .2 4 0 0 0 G ram
1 .4 2
0 .9 6
4 .1 7 5 3 5
1 2 9 .8 1
7 4 .7 3
0 .0 1
4 .1 6 0 5 4
1 2 9 .3 5
74.50
0.00
0.00
0.00
2 0 .4 0
7 .0 0
0 .0 0
0 .0 0
0 .0 0
0 .0 0
0 .0 0
0 .0 0
0 .0 0
E q. Wt C ati ons
2 0 .0 4
1 2 .1 5
0 .0 0 0
6 1 .0 3
3 0 .0 2
1 .2 2 1
0 .0 0 0
0 .0 0 1
Total Hardness, as CaCO3
Residual A lkalinit y
Residual A lkalinit y
pH Shif t RE Dist illed Wat er
Ionic Strengt h, non carbo
Ionic Strengt h, carbo
Total Ionic St rengt h
pfm
0 .0 0 0
0 .4 2 5
0 .1 9 7
0 .0 0 0
0 .0 0 0
4 8 .0 4
3 5 .4 5
6 2 .0 0
4 7 .0 0
2 2 .9 9
3 9 .1 0
2 7 .9 2
1 8 .6 2
0 .0 0 0
0 .0 0 0
0 .0 0 0
0 .0 0 0
3 2 .0 1
0 .0 0 0
Charges
Imbal
Imbal %
A lkalinit y
Ca Hardness, as CaCO3
Mg Hardness, as CaCO3
A nions
1 .4 2 0
0 .9 6 0
2.381
0.538
12.74%
2 3 1 7 3 .1 7 4
1.843
62.00
71.00
48.00
119.00
34.86 ppm as C aC O 3
0.70 mE q/L
0.06
2 .9 0
0 .6 1 2 2 4
3 .5 2
0 .0 3 9 2
94
0 .0 3 5 8 9 1 0pfm, no c arbo
Approach to Synthesis
• Simply add anything that is deficient!
– Catch: You must add salts. Ratio of calcium to chloride in CaCl2 is fixed!
(100mg Ca:35mg Cl)
– Nevertheless you can do quite well using a few common salts
• NaCl, MgSO4.7H20, NaHCO3 Source - grocery or drugstore
– Table salt (don’t use iodized!), epsom salts, baking soda
• CaSO4.2H20, CaCO3, CaCl2.2H2O Source homebrew supply shop
– Gypsum, (precipitated) chalk, calcium chloride
– If using carbonate, bicarbonate or changing alkalinity you will need acid
• This can be CO2
• Sulfuric or Hydrochloric (not recommended: FCC, USP, safety)
– Math is nettlesome: successive approximations by manipulation of salt
addition amounts until combined error in ion concentrations is small
– Excel Solver to the rescue!
• Set up the problem and let the Solver do the work.
FCC = Food Chemicals Codex i.e. approved for use in food for human consumption
USP = United States Pharmacopoeia i.e. approved for use in drugs for humans
95
Adding an Ion from a Salt
• Gypsum is CaSO4.2H2O GMW 172.14
• Each millimole of 172.14 mg contains 40 mg of Ca++ and
98 mg of SO4-• To add, for example, 60 mg/L Ca++ would require 60/40 =
1.5 mMol = 258.2 mg gypsum for each litre treated
– And you are also adding 1.5*98 = 147 mg/L SO4-- like it or not.
• To add 250 mg/L sulfate use 250/98 = 2.55 mMol = 440
mg/L
– And you are also adding 2.55*40 = 102 mg/L Ca++ like it or not.
• Spreadsheet does all this math for you.
• Compromise necessary because of fixed relative amounts
of ions in salts
• If target is reasonable, spreadsheet can do a fairly good
96
job and it’s a lot easier than doing the math yourself
Synthesis Portion of Spreadsheet
Resulting ion concentrations
Specify salt additions here
Salt s/A cids
A ddit ion, mg/L
Calcium, mMol/L
Magnesium, mMol/L
CaCl2.2H20 NaCl
CaSO4.2H20 MgSO4.7H20 CaCO3
NaHCO 3 CO2
HCl
0.00
14.95
1386.65
75.96
55.35
136.41
0.00
0 .0 0
8 .0 5
Sulf at e, mMol/L
Chloride, mMol/L
Nit rat e, mMol/L
Nit rit e, mMol/L
Sodium, mMol/L
Potassium, mMol/L
Fe(II), mg/L
Fe(III), mg/L
H2SO4
0.00
0.00
T ota l, mg/L
pRatio
Weight s Errors, % Errors, mg/L
350.6156
- 0 .0 0 2
1
- 0 .4 %
- 1 .3 8 4 3 5 2
23.9935
0 .0 0 0
1
0 .0 % - 0 .0 0 6 4 7 5 4
0 .0 0
0 .3 1
Total Carbo mMol/L
Carbonic, mMol/L
Bicarb. mMol/L
Carbonat e, mMol/L
Prot on excess mEq/L
0 .5 5
0 .2 1
0 .3 4
0 .0 0
- 0 .7 6
8 .0 5
0 .0 0
1 .6 2
0 .6 1
1 .0 1
0 .0 0
- 0 .6 1
0 .0 0
0 .0 0
0 .0 0
0 .0 0
0 .0 0
0
0
0 .3 1
0
0 .2 6
0
0 .2 6
1 .6 2
Free A mmonia, mg/L
Ionic Strengt h
E x tra ~ pH s hift
C a rbonic ~ a ddit ion
E x tra non c a rbo
S y nthe si zed ca rbo
S y nthe si zed non c a rbo
S y nthe si zed tota l
S y nthe si zed pfm w/o c a rbo
S y nthe si zed pfm w/ c a rbo
Vol. + f or Gal - f or L
Lit res
0 .6 8 6 5
0 .6 7 8 3
3 4 .5 1 6 2
1 .9 7 7 0
3 7 .4 1 9 6
3 9 .3 9 6 6
0 .1 0 7 7
0 .1 0 9 8
Relative importance
in computing error
6.3375
105.0914
240.9737
0.0398
0.0000
0 .0 3 7
1
8 .8 %
- 1 9 .5 2
0 .0 0 2
1
0 .4 %
0 .0 0 2
1
0 .4 %
0 .0 0 0
0
0 .0 %
0 .0 0 0
0
0 .0 %
- 0 .0 0 8
1
- 1 .8 %
0 .0 0 0
0
0 .0 %
0 .0 0 0
0 .0 %
0 .0 0 0
0 .0 %
0 .0 0 0
0 .0 %
0 .0 0 0
0 .0 0 0 0
0 .0 0 0
0
0 .0 %
MSE
Wt 'd MSE MSE,%
0 .0 0 1 0 .0 0 1 4 2
0 .3 %
0 .0 0 0
H + I mbal.
3 .1 7
0 .0 7
- 1 8 .0 0
0 .0 0
- 0 .7 9
0 .0 0
0 .0 0
0 .0 0
0 .0 0
823.1663
16.0704
0.0000
0.0000
43.2068
0.0000
0 .0 0 0 0
0 .0 0 0 0
SYNTHESIS
A llkalinit y
Ca Hardness, as CaCO3
Mg Hardness, as CaCO3
198.0818
874.7895
98.7185
Total Hardness
973.5080
Residual A lkalinit y
Residual A lkalinit y
pH Shif t RE Dist illed Wat er
-65.9607
-1.3192
-0.11
0 .0 0
54
2 0 4 .4 1 1 6
Grams of salt or acid
0 .0 0 0
3 .0 5 6
2 8 3 .4 4 8
1 5 .5 2 6
1 1 .3 1 4
2 7 .8 8 4
0 .0 0 0
0 .0 0 0
0 .0 0 0
A mount in ot her unit s
0 .0 0
0 .0 1
0 .6 2
0 .0 3
0 .0 2
0 .0 6
0 .0 0
0 .0 0
0 .0 0
Unit s
P ounds ^ P ounds ^ P ounds
^ P ounds ^
P ounds ^ P ounds ^ P ounds ^ mL 2 3 B e' mL 9 6 % 1 .8 5 6 g/L
A mount in Oz.
0 .0 0
0 .1 1
9 .9 9
0 .5 5
0 .4 0
0 .9 8
0 .0 0
Salt s/A cids
CaCl2.2H20 NaCl
CaSO4.2H20 MgSO4.7H20 CaCO3
NaHCO 3 CO2
HCl
H2SO4
97
Water Worksheet Summarized
• Three parts (two identical)
– These two accept your inputs of pH, alkalinity(as CaCO3 or mEq),
hardness (as CaCO3 or mg/L), other ion content, temperature (°F
or °C)
– Compute balance, residual alkalinity, ionic strength, carbo species
ratios and fractions
• Must have balanced target; should have balanced source
– One on left is for source water
– One on right is for target water profile
– Middle part is for synthesis of target from source
•
•
•
•
Manually indicate the amount of each salt or acid you want to try
Check errors (differences between desired and realized)
Adjust until “close enough for government work”
Better still: Let Excel Solver do this for you
• Detailed instructions on Sheet 2 of spreadsheet
98
More on Acid Requirements
• If you use NaHCO3 and/or CaCO3 in a synthesis pH will most
probably shift and CaCO3 probably won’t dissolve
– Acid is required to set pH to desired value and dissolve CaCO3
– If you have used these to match alkalinity and then intend to decarbonate,
save yourself the trouble - synthesize for stylistic ions only
• Much will probably precipitate when water is heated in HLT
• I do not recommend the use of strong mineral acids for safety reasons
• That leaves CO2. Add salts and stir. Water will be cloudy as CaCO3
will be in suspension
• Bubble CO2 through water until it clears and pH is about right - this
may take some time (hours).
– Pressure helps dissolve CO2 - put salts in Corny keg, pressurize, agitate
– Target pH not that critical. Will go where it wants to in HLT, mashtun
99
Part VI
Treatment
100
At Water Treatment Plant
• Depending on source, strong oxidants may be used to
“burn” off flavors, aromas
– Chlorine, potassium permanganate
• Mix with salt of trivalent metal (Fe, Al)
– Forms hydroxide gel which is allowed to settle
– Drags down particles (silt, bacteria, viruses) with it
• Decant, filter (may include active carbon)…
• Adjust alkalinity, hardness, pH
– Same way we do! Add acids, lime, salts to desired profile
– Mostly for protection of distribution system
– Set to near saturation pH (small amounts of lime precipitated)
• Inject chlorine and/or ammonia and/or ozone
• Send to distribution system
101
At Home - Well
• Wound filters remove particulates
• If iron is present Aeration/sand filter (or greensand filter)
• If water is acidic (subterranean CO2) run through limestone
(neutralizer). Prevents corrosion; increases hardness and alkalinity.
• Softener - Don’t use for brewing water!
– Ion exchange resin loaded with Na+ (sometimes K+)
– Replaces Ca++, Mg++ with Na+ (sometimes K+)
– Backwash with brine, NaCl (or KCl) recharges medium. Replaces Na+
(or K+) while Ca++, Mg++ go down drain.
• Removes beneficial hardness and replaces with useless Na+ (or K+)
• Reverse Osmosis (RO) units force water through membrane with small
pores removing most ions (95-99%)
• Activated carbon filter: removes organics, mustiness…
• Anion/Cation ion echanger (see next slide)
102
At Home - City Water
• Wound filters remove particulates
• Softener - Don’t use for brewing water!
• Activated carbon filter: removes chlorine, chloramine,
organics
– Required if RO unit is installed - HOCl, H2NCl poison membrane
– Available as whole house or at sink installations
• Reverse Osmosis (RO) units force water through
membrane with small pores removing most ions (95-99%)
• Cation/Anion exchanger:
– Swaps H+ for all cations, (OH)- for all anions. Result: DI water.
– Brita filters in this class (also contain silver as Ag+ is
bacteriostatic)
103
Decarbonation/Softening
• Goal is decarbonation (reduction of alkalinity). Softening
is the price that usually must be paid.
– Ca++ + 2HCO3- heat
-----> CO2 + CaCO3 + H2O
• Calcium is removed but only to extent of bicarbonate e.g water with
alkalinity of 100 ppm as CaCO3 and hardness of 200 ppm as CaCO3
precipitates all (theoretically) its bicarbonate and half its calcium
– Decarbonation limit practially about 50 ppm as CaCO3
• Calcium so precipitated is called temporary hardness
• Remaining calcium is called permanent hardness
– Ca(OH)2 + Ca++ + 2HCO3- ----> 2H2O + 2CaCO3
• This is actually neutralization of the acid HCO3- with the base
Ca(OH)2 which suggests procedure (next slide)
• Decarbonation limit practially about 50 ppm as CaCO3
– Ca++ + 2HCO3- + 2HCl ----> 2CO2 + Ca++ + 2Cl- + 2H2O
• No softening: temporary (carbonate hardness) converted to permanent
(non carbonate hardness) - no decarbonation limit
104
Lime Decarbonation
• Calculate amount of lime required
– CaO (quick lime) + H2O --> Ca(OH)2 (slaked lime) + heat
• Pickling lime is slaked. Available in canning section of supermarket
– 1 mMol of slaked lime (74 mg) treats 2 mEq bicarbonate (122 mg
or 100 ppm as CaCO3 alkalinity)
• Ca(OH)2 + Ca++ + 2HCO3- ----> 2H2O + 2CaCO3
• All added calcium precipitates. No hardness increase (theoretically)
– DeClerck recommends treating trial batches with this amount and
±10%. Then use dose that gave best results
• Add to 2/3 the water to be treated
– Wait for Mg(OH)2 to precipitate and decant if
• Called (split treatment). Only necessary if Mg is to be reduced
• Excess lime with only 2/3 water raises pH to where Mg(OH)2 forms
– Titrate back to pH 8 or so with remaining volume
– Allow to settle and decant
105
Iron
• Fe++ (clearwater iron) is soluble
• Fe(OH)3 is insoluble (ugly brown) gel
• Approach to treatment is, thus, to oxidize any Fe++ to
Fe+++, at higher pH Fe(OH)3 gel forms. Filter gel
– 4Fe++ + 2H2O + O2 +8(OH)- --> 4Fe(OH)3 (gel)
– Gel gets caught by sand. Backwash to dispose
– Aeration supplies oxygen and sweeps CO2 raising pH, increasing (OH)-
• Aeration by spraying, sparging with air, pouring back and
forth then pouring through clean sand works
• Commercial units inject air and then pass through sand bed
- similar construction as neutralizers, softeners
• Manganese greensand oxidizes Fe++ (and Mn++ and S-)
and traps gels
– It’s Mn(IV) that does job. Recharge with Mn (VII) i.e. KMnO4
106
Chlorine/Chloramine
• These must be removed from brewing water
– Form chlorphenolics with plastic, bandaid flavor at ppb level.
• Water treatment plants have bubbled chlorine gas into
product for years - significant public health factor
– H2O + Cl2 <--> H+ + Cl- + HOCl
• Uncharged hypochlorous acid slips through bacterial cell wall
disabling key enzymes - strong oxidizing agent
– Standing, boiling, sparging reverses reaction removing
chlorine
• More recently, ammonia is added after chlorination
– NH3 + HOCl --> H2O + H2NCl : Monochloramine
• Less likely to produce Trihalomethanes (THMs)
• More stable (persistent) in distribution system
• More persistent when you try to remove it
107
Removing Chloramine
• Boiling is effective but it takes an hour or more
• Granulated activated charcoal (GAC) filters are
effective but make sure contact time is long
enough
– Limit flow rate
– If you can smell it, it “broke through”
• Simplest treatment: 1 Campden Tablet for 20 gal.
– Crush and suspend in a small amount of water, stir in.
108
Part -XX
Comparison Beer
109
“…and why was Burton Built on Trent?”
A. E. Houseman, Shropshire Lad
•
•
“…well water drawn from the evaporite-rich Permo-Triassic sandstones
outside of town”
It must make good beer because water doesn’t taste very good
– High sulfate accentuates hop character, stabilizes beer biologically (IPA)
•
I have 7 profiles for Burton (all on handout CD). One which balances at
pH 6.6 (i.e. a “reasonable” one) and shows:
–
–
–
–
–
–
–
•
•
•
Alkalinity: 182 ppm as CaCO3
Calcium Hardness: 878 ppm as CaCO3
Mg Hardness: 99 ppm as CaCO3
Residual Alkalinity - 83 ppm as CaCO3 (pH Shift -0.17)
Sulfate: 820 mg/L
Chloride: 16 mg/L
Sodium: 44 mg/L
This one was implemented with well water, baking soda, table salt (not
iodized), epsom salts, gypsum, precipitated chalk and CO2.
1.5 bbl batch brewed using Maris Otter, some Munich, 1058 London
ale, Sterling, US Kent Goldings and EKS - 12.7°P
Same beer brewed with untreated well water
110
Brewing
200
180
Temperature, °F
160
Bat ch 126a (Burton - done f irst)
and 126b (normal water) ales
Masht un 1
Masht un 2
140
120
100
80
12:30 PM
9/8/08
3:00 PM
5:30 PM
8:00 PM
10:30 PM
111
Time, Z
Fermentation
64
62
60
58
56
Temperature, °F
54
52
50
48
Fermentation History: Ale Batches 126a and 126b
!26b - Normal Water
126a - Burtonized Water
46
44
42
40
38
36
34
9/9/08
9/11/08
9/13/08
9/15/08
9/17/08
Time, Z
9/19/08
9/21/08
112
Tasting
• Look for differences in
– Esters (aroma & flavor): Fruit, berry…
– Yeast aroma: Bready?
– Hops: (aroma & flavor):bitterness, sharpness,
coarseness, fruity
– Sweetness
– Mouthfeel: viscosity, mellowness, astringency/dryness,
rough/smooth, bite
• Is one beer “better” than the other?
– If so and it’s the Burtonized one is it enough better that
it’s worth the trouble?
113
114
Further Reading
•
•
•
•
•
•
•
•
Basic inorganic chemistry text
The articles on the handout CD
Palmer, John, How to Brew 978-0-937381-88-5
Hardwick, W. A. (Ed.) Handbook of Brewing 0-8247-8908-3
De Clerck, J. A Textbook of Brewing (no ISBN! – get it from Siebel)
Noonan, G, New Brewing Lager Beer 0-937381-46-2
Foster, Terry, Pale Ale 2nd Edition 0-937381-69-1
Eaton, et al. Eds. Standard Methods for the Examination of Water and
Wastewater
115