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investigation into the water quality of “Castle” beer and its main water source

12/02/2012

Abstract

This report covers an investigation into the water quality of “Castle” beer and its main water source. Chemical analyses were performed on water collected from the Newlands water stream and on a “Castle” beer sample taken from the SAB breweries in Newlands. The Newlands stream is the main source of water for the manufacture of “Castle “ beer.

 It is important that the chemical composition of water is of an adequate condition for use by consumers. The domestic water quality standards that are presented in the literature vary in the standards suggested for the different elements and compounds.  For example, the South African standards for domestic water use (1995) are different from other international standards such as the World Health Organisation (WHO) and the European Community (EU).  Elements such as iron, manganese, and chromium appear in the above guides in different permitted levels. For example, the level of iron permitted by the South African standards is <500 ppm, whereas the EU permitted level is only <200 ppm.

 The analysed samples vary considerably in their chemical characteristics. The water stream has a neutral pH  (6.86) whereas the beer is acidic (4.25). The water has a much lower EC (174 mS/cm) than the beer (1212 mS/cm). The amount of  total dissolved solids (TDS) in the beer (776 mg/L) is considerably greater than that of the water stream (111 mg/L).

  The reason for the different chemical nature of the two samples lies with the process of beer production. In this process, a considerable amount of salt, in different forms (sulphates, phosphates, chlorides) and metals are added as a means of improving flavour and odour. The writer suggests that the chemical speciation of the water is under a marine influence due to the dominance of sodium chloride in the water.

 

The determination of elements in the solution of beer reveals concentration levels that are above the guidelines suggested by the department of Water Affairs (1995) for industrial manufacturing of beverages. The following elements were found to exceed these guidelines: potassium, calcium, magnesium as major ions as well as trace elements such as aluminium, chromium, iron, manganese and zinc.

 

Performing a chemical speciation analysis for a hypothetical (yet, a reasonable) scenario for the water and the beer reveals that salinisation of the water can greatly affect the water quality and change the mineralogical and chemical speciation. However, It may still be adequate for the production of beer. A drop in the pH level during the process of beer manufacture may lead to a change in the chemical and mineralogical speciation as well. However, this change should be evaluated by means of food technology and not geochemistry.


Table of contents

  Abstract……………………………………………………………………………………

List of figures…………………………………………………………………………………………..IV

List of tables……………………………………………………………………………………………IV

1. Introduction…………………………………………………………………………..1

1.1. Background to investigation…………………………………………………………. 1

1.2. Objectives of this report………………………………………………………………..1

1.3  Procedures used to evaluate the geochemical nature of the samples…1

1.3.1. Domestic water quality…………………………………………………………2

1.3.2. Commercial water quality……………………………………………………..2

          2. Sampling and analytical methods…………………………………………..3

2.1. Water sample locality……………………………………………………………………3

2.2. Beer sample locality……………………………………………………………………..3

2.3. Analytical methods……………………………………………………………………….3

2.3.1. Chemical analysis……………………………………………………………… 3

2.3.2. MinteqA2 reaction path modelling…………………………………………..5

          3. Analysis results……………………………………………………………………..6

3.1. pH determination………………………………………………………………………….6

3.2. Electrical conductivity (EC) ……………………………………………………………6

3.3. Alkalinity determination………………………………………………………………… 6

3.4. Ion chromatography (IC) analysis………………………………………………….. 6

3.5. Charge balance……………………………………………………………………………8

3.6. Silica determination………………………………………………………………………9

3.7. Phosphate determination……………………………………………………………… 9

3.8. Fluoride determination…………………………………………………………………..9

3.9. Dissolved organic carbon (DOC) determination………………………………..9

3.10. Ion coupled plasma – mass spectrometer (ICP-MS) determination…….9

3.11. MinteqA2 reaction path modelling…………………………………………………10

         

 

                                                                                                                     Page

4. Discussion…………………………………………………………………………….13

4.1. Water analysis…………………………………………………………………………….13

4.2. Beer analysis………………………………………………………………………………15

4.3. MinteqA2 hypothetical scenario……………………………………………………. 18

4.3.1. Water salinisation……………………………………………………………… 18

4.3.2. Beer acidification………………………………………………………………. 19

5. Conclusions…………………………………………………………………………. 21

5.1. Newlands water spring sample………………………………………………………21

5.2. Mediating process………………………………………………………………………. 21

5.3. “Castle” beer sample……………………………………………………………………21

          6. Reference…………………………………………………………………………….. 22

7. Appendix A: Analytical methods…………………………………………… 23

7.1. Determination of electrical conductivity (EC)………………………………….. 23

7.2. Determination of pH values…………………………………………………………..23

7.3. Determination of alkalinity…………………………………………………………….23

7.4. Cation and anion measurements using Ion chromatography (IC)……… 24

7.5. Determination of phosphorus – P – concentration……………………………25

7.6. Determination of fluoride – F – concentration…………………………………. 25

7.7. Determination of silica – Si – concentration……………………………………. 26

7.8. Inductively coupled plasma – mass spectrometer (ICP-MS)………………26

7.9. Determination of dissolved organic carbon (DOC)……………………………27

7.10. MinteqA2 reaction path modelling………………………………………………..27

          8. Appendix B: group results……………………………………………………..28

8.1. Results……………………………………………………………………………………….28

8.2. Interpretation and discussion…………………………………………………………28

 

List of tables

                                                                                                                                                            Page

Table I             Chemical parameters and constituents………………………………………………………..            7

Table II            Distribution of water components among dissolved and adsorbed species……….  10

Table III           Saturation indices of the water stream sample………………………………………………      11

Table IV           Distribution of beer components among dissolved and adsorbed species…………            11

Table V            Saturation indices of the beer …………………………………………………………………….     12

Table VI           a comparison of the Newlands water spring during the summer of1997/8…………          14

Table VII          Constituents that contribute to problems in an industrial process……………………..         16

Table VIII         Limiting & average levels of factors influencing the quality of beer ………………….. 17

Table IX           Distribution of water components among dissolved and adsorbed species……….. 19

Table X            Distribution of beer components among dissolved and adsorbed species………….           20

Table XI           Alkalinity calculations for water stream sample………………………………………………      24

Table XII          Group results……………………………………………………………………………………………..  25

 

 

 

List of figures

Figure 1           Ion Chromatography analysis – ion detection in the water stream sample………….           8

Figure 2           Alkalinity determination using Gran titration………………………………………………….. 23

Figure 3           Phosphate determination in the water stream sample…………………………………….     25

Figure 4           Silica determination of the water stream sample……………………………………………         26

Figure 5          SAR interpretation of the group results ………………………………………………………..       28

Introduction

T

his report describes the geochemical analysis of “Castle” beer in comparison with its major water source – the Newlands water stream.

1.1. Background to investigation

The decision to conduct this analysis arose from in the aqueous geochemistry module studied at UCT. Each student was to conduct a thorough water analysis and a comparison between two water samples that were geochemically connected. Comparing a beverage to its water source was suggested and acted upon.

1.2. Objectives of this report

The objectives of this report therefore are to:¨ Describe the chemical composition of the water source and the beer.¨ Evaluate the probable reasons for the change in the chemical composition and to discuss the chemical characteristics (Surroundings, processes, speciation, possible reactions) of the water and beer samples. ¨ Compare it to the permitted levels by the South African Water Affairs standards (1995).

1.3. Procedures used to evaluate the geochemical nature of the samples

Beer is a common beverage.  As with many other beverages, we have a tendency not to question the quality of the substance: just the quality of the taste.  However, it is important from time to time to pause and examine the ingredients of an artificial drink.

It is a common practice to add salts such as phosphates, sulphates, chloride and even iron to the beer as a measure of flavour control. Therefore, high amounts of dissolved solids and organic matter can be expected in the beer, as well as a variety of pH levels.

There are many beers available on the South African market.  Some imported and some local.  For the purpose of this water test, a very common beer is tested.

The beer chosen for this intensive water quality testing process is “Castle” lager, manufactured by the South African Breweries in Newlands, Cape Town. In addition, a water sample was taken from the water stream that provides 80% of the water used for the manufacture of “Castle” beer and some other beverages (S. Wade. Personal Communication, 1998).

The different categories in the water quality are of great importance. In this paper two major influencing factors will be reviewed in the light of some of these categories:

¨ Water quality for domestic use.

¨ Standards required for commercial use.

1.3.1. Domestic water quality

In the common view of water quality for domestic use it is important that the water composition will be of an adequate condition for the use of the consumers. The domestic water quality standards that are presented in the literature vary in the standards suggested for the different elements and compounds, and vary in the elaboration of these elements and compounds. For example: the South African standards for domestic water use (1995) are incomplete. Furthermore, they are different from other international standards such as the World Health Organisation (WHO) and the European Community (EU).  Elements such as iron, manganese, and chromium appear in the above guides in different permitted levels. The level of

iron permitted by the South African standards is <500 ppm, whereas the EU permitted level is only <200 ppm.

1.3.2. Commercial water quality

In the case of beer making, traditionally the type of water available to a brewery determined the kind of beer produced. It will be shown that organic matter and some inorganic ions have a profound effect on the beer during its manufacture and consequently on its chemical evaluation. This is of special important when a beer sample is compared with required standards.

The beer is not evaluated in the light of food technology, but through a geochemical perspective. This report should be read and evaluated from this geochemical point of view.

2. Sampling and analytical methods

The samples to be analysed were provided to the writer by the Food Technologist of SAB Breweries in Newlands. The samples consist of two water bottles and a six-pack of “Castle” beer bottles.

2.1. Water sample locality

SAB breweries are using two water sources for the making of beer. The first is the Newlands spring and the second is Kommetjie spring, both located in Newlands, Cape Town. They donate 80% and 20 % of the water, respectively.

The water samples were taken from the Newlands spring. They consisted of two water bottles of ½ a liter each.

2.2. Beer sample locality

The beers were taken from the ordinary stock to be shipped out, and therefore were not selected especially beforehand.

All samples were stored in a refrigerator at "16Bc.

Most of the chemical analysis procedures described here were performed within the Department of Geological sciences at the University of Cape Town. Further details of the analytical procedures, including discussion of the precision and accuracy associated with the various techniques, are provided in Appendix A.

The beer sample will be referred hereafter as the “beer” and the water stream sample as the “water”.

2.3. Analytical methods

2.3.1. Chemical analysis

The water and beer samples were initially analysed for pH (appendix A 7.2) and electrical conductivity (EC) using automated pH and EC (appendix A 7.1) meters respectively. The total dissolved solids (TDS) was calculated according to the following equation:

TDS (mg/L)  = EC (mS/cm) * 640.

Alkalinity (HCO3 mg/L) was determined via a method of Gran titration (appendix A 7.3), by which a sample was titrated by HCl to pH 4 and than gradually by 0.2 increments to pH 3.2. The alkalinity was determined from the equivalent point (i.e. to neutralise all alkalinity).

A portion (100ml) of the samples was filtered using 0.45 mm Millipore filters prior to their analysis for their various constituents. The majority of the cations (K, Na, Ca, Mg, NH4, Mn & Li) and anions (Cl, F, NOx, PO4, SO4 & Br), were obtained using Ion Chromatography- IC (Appendix A 7.4).

Phosphorus concentration was determined using the phosphomolybdate colorimetric method  (Appendix A 7.5).

Silica concentrations were measured using the heteropoly blue colorimetric method (Appendix A 7.7). The silicon ion analysis is of the soluble form, with no reference to monomers and colloids.

The Fluoride ion was determined by means of Specific ion electrode (Appendix A 7.6).  The analytical range is between 0.1 to 10mg/L. It is agreed (Fey, personal communication, 1998) that any result having a level above 30mV has a fluoride level less than 1 mg/L (Fey, Personal Communication, 1998).

Trace elements were quantitatively determined by Ioned Coupled Plasma – Mass Spectrometer, ICP-MS. (appendix A 7.8). The results consist only of the positive oxidation states (all of them together) of the detected element.

A filtered sample (0.45 mm) was run through the system to produce a set of trace element output. It is important to bear in mind that some interference exists and affects the resulting interpretation. For example a spectral ion effect of the argon ion (Ar+, Ar2+) influences the iron display. This happens by creating a larger concentration display than the genuine concentration.

Different isotopes present in the solution may have isobaric effects on the outcome of some species, since some isotopes have the same mass as a different element (54Fe+ º 40Ar 14N+).

Dissolved organic carbon (DOC) was analysed at the CSIR laboratories in Stellenbosch. The method that was used is the Persulphate-Ultraviolet Oxidation method.

The samples to be analysed are filtered through a 0.45 mm Millipore filter membrane to

remove suspended solids.   Thus, some of the organic carbon present in the dissolved organic matter will not be calculated due to its being filtered out.

Organic carbon is oxidised to carbon dioxide, CO2, by persulphate in the presence of ultraviolet light. Then it is reduced to methane and measured by flame ionisation detector, or by a chemical titration. The minimum detection level is 0.05 mg/L of organic carbon.

Determination of dissolved organic matter (DOM) can be calculated from the following equation (standard methods, 1989):

DOM (mg/L) = [DOC (mg C/L)*2)(5*10-4).

This method of determining DOM was suggested by Nowicki.T.(unpublished Ph.D. thesis, UCT, 1997). Yet, it has a limitation. In pH levels beneath 5 it is not sufficient, and a broader analysis should be carried out (Nowicki.T. 1997). Therefore, for the beer sample the DOM was determined by this method, even though it does not seem to be the best possibility for DOM determination.

Quantitative analysis of the different ions present in the solution by IC and ICP methods does not include all the elements present in the solution, the reason being the presence of organic matter. The DOM has a high surface area and a considerable ability to bind cations.

Part of the DOM is filtered out through a 0.45 mm filter. Thus, it may happen that a significant amount of cations (in respect with total ionic

concentration) will be filtered out together with the DOM and will not be present in the overall analysis of the ion characterisation of the solution.

Inevitably, it will cause a further miscalculation of the charge balance (likely to have an excess of anions), and when running computerised simulation modules for reaction path modelling, such as MinteqA2, it will produce an inaccurate report of the solution’s chemical and mineralogical nature of the solution.

Therefore in order to be able to calculate a reasonable overall charge balance and run the MinteqA2 reaction path model, it was assumed that the concentration of the DOM is not the one calculated, but a smaller portion. This portion of DOM is the amount that will balance the excess of cations calculated from the IC and ICP-MS analysis.

2.3.2. MinteqA2 reaction path modelling

The main calculations that the minteqA2 reaction path model can do are:

¨ Total charge balance.

¨ Distribution of the elements in a solution.

¨ Saturation indices.

The program was run for each sample (water, beer), in two different modes. The first, is a standard mode in which no precipitation occurs. In the second mode, the precipitation of oversaturated species is allowed.

The concentration of the elements that were chosen for the purpose of running the model were taken from the IC, ICP-MS and the different colorimetrical methods that were conducted.  The silicon concentration was taken from the ICP-MS determination. The fluoride levels were taken from the colorimetric determination method. The water phosphate level was taken from the colorimetric determination.

A hypothetical scenario was run through minteq to examine possible chemical changes in the aqueous phases of the beer and the water. The water sample was tested for a possible excess of sulphates in the chemical composition. The beer was examined for changes in the pH values.

3. Analysis Results

3.1. pH determination

The pH values of the water and the beer samples were 6.86 and 4.25 respectively.

3.2. Electrical conductivity (EC)

The EC of the water was 175 mS/cm, whereas the beer had 1212  mS/cm.

The total dissolved solids (TDS) levels were determined from the EC levels, and are therefore 776 mg/L for the beer and 111 mg/L for the water stream sample.

3.3. Alkalinity Determination

Alkalinity determination yielded the following results for the water sample: 9.7 10-6 mg/l of  HCO3.

As for the beer sample, at pH levels below 5 it is possible to assume (Fey, Personal Communication, 1998) that the level of alkalinity is very low and therefore can be considered as 0.

3.4. Ion Chromatography (IC) analysis

The Ion Chromatography analysis results are presented in Table no 1 (page 3).

The water sample analysis indicates that the major cations in the solution are sodium (16.3 mg/L) and calcium (13.3 mg/L). Smaller amounts of Potassium and Magnesium were also detected.

Lithium was detected as well, but in a trace quantity. In addition, the lithium level detected by the IC method contradicts the level detected by the ICP-MS method (1.5 ppb). It is clear that the 400-fold difference is a significant one.  In this paper, for the purpose of further data interpretation, such as MinteqA2 modelling, the level detected by the ICP-MS is the concentration chosen to be related to.

Anion analysis resulted in two anions: chlorine, as a major anion (35 mg/L) and sulphate (5.8 mg/L). A trace quantity of fluoride was detected as well. For the purpose of this paper the fluoride level will be regarded as less than 1 mg/L. That complies with further findings of fluoride concentration done by colorimatry methods.

It is apparent that sodium and chlorine are the major ions in the water. It should be noted that the environment in which the water source escapes from the soil, and the geological background, are closely related (physically, and perhaps chemically) to the nearby Atlantic Ocean. The ocean is known to have high levels of sodium-chloride (30 g/Kg water) in its waters, and in the atmosphere (Drever, 1997).

Next to be analysed by the IC is the “Castle” beer. The results are presented in Table 1 (page 7). The outcome of the beer analysis is more complex than that of its water source.

The anions observed are chlorine, sulphate, nitrate and phosphate, which is the major anion

Table I     
Chemical parameters and constituents

Sample

Beer

 

Water Stream

Industry

(category2)

Aquatic eco-systems

Domestic water

 Chemical parameters

pH

4.25

6.86

>6

EC (mS/cm)

1212

174

TDS  g/L

77.6

11.1

<300

Alkalinity (mg CaCO3)

0

9.7*106

0-120

 

Chemical Constituents

By Ion Chromatography:

mg/l

mg/l

mg/l

mg/l

mg/l

Sodium               Na+

12.2

16.3

<200

Potassium          K+

331

1.42

<50

Lithium              Li+

6.12

0.6

Ammonium        NH4+

16.7

Bdl

Calcium             Ca2+

124

13.3

<5*10-5

<32

Magnesium       Mg2+

127

2

<70

Chloride            Cl

128

35

0-400

<0.012

<600

Fluoride            Fl

Less than 1

Less than 1

<0.05

<0.75

Nitrate               NO3

6.4

Bdl

<0.5

<10

Phosphate        PO4

496

Bdl

<0.005

Sulphate           SO4

188

5.8

0-80

<200

 By Colorimatry / Electrode
Phosphate       PO4

n/a

1.25

<0.005

Fluoride          Fl

68.3

1

<0.05

<0.75

Silicon            Si

n/a

24.3

0-20

DOC (mg C / L)

33040

2.7

<5

 By ICP-MS

ppb

ppb

ppb

ppb

ppb

Lithium                Li

1.6

1.5

2+

Aluminium          Al

739

3.82

 

<0.5

<500 (EU-200)

Silicon                 Si

19722

2955

0-20000

Chromium          Cr

622

1.74

*Cr +6 – <10

*<50 (EU,WHO)

Iron                     Fe

691

61.5

0-200

10% of background dissolved concentration

<500

       <200 (EU)

Manganese        Mn

115

16.9

0-100

<180

<5 (EU-50)

Nickel                Ni

5.71

2.48

20 (EU,WHO)

Copper               Cu

45.8

4.16

2000 (EU,WHO)

Zinc                   Zn

17.5

23.4

<2

<10

Arsenic              As

9.74

0.3

10

<10

Selenium           Se

5.52

0.9

<2

<20

Molybdenum     Mo

7.48

0.56

<70 (WHO)

Cadmium          Cd

0.75

0.16

<0.07

<5

Barium              Ba

28.3

7.37

700  (WHO)

Thallium           Tl

0.04

0

Lead                  Pb

2.46

0.84

<0.2

<10

Thorium           Th

0.18

0

<228

Uranium           U

0.06

0

<70

present (496 mg/L). The fluoride ion was detected by the IC as well, but for reasons discussed later it is not considered to be a correct finding. It can be noticed in figure 1 that the base-line flow in the anion analysis is of an irregular nature.

Figure1: IC ion detection in the water

As seen in Figure 1, the base-line does not flow in a straight line. The base-line descents at the beginning (anticipated) and than ascending along and under the fluoride and chloride and ending after the nitrite peak. It is an unwanted phenomenon that interfered with the proper evaluation of the results. For example, the fluoride does not have a clear straight base-line and in addition has a double peak.

Its concentration outcome suggests a level of 68 mg/L. It is a level which is 100 fold greater than the level permitted (0.75 mg/L) by the South African water quality guidelines (1995).

The beer, by its nature, consists of organic acids such as oxalate and acetate. The time sequence in which some of these acids appear in the IC analysis is worthy of note, since they overlap with some of the anions that are analysed by the IC. An overlap, or a considerable background “noise” can cause an element to appear in greater concentration than its original level.

The cation analysis of the beer presents six elements: potassium, magnesium, calcium, ammonium, sodium and lithium. The first ion has the most significant presence of all (K – 331 mg/L) The second and third, were medium in their presence (127 mg/L Mg, 123 mg/L Ca). The last three elements are present in small concentrations (<20 mg/L). The lithium level shows, in a similar manner to the water analysis, a contradictory result with other methods of analysis (ICP-MS). And, as with the water analysis, the lithium level in the beer is taken from the ICP-MS results.

3.5. Charge Balance

The charge balance is presented in Table 1.  The charge balance was computed with the fraction of the DOM to balance it (i.e. topping up the anions with the DOM to create a reasonably balanced solution). It is widely accepted that a solution with an excess of anion/cation of less than 5% can be considered as a balanced solution (with respect to the ionic charge). Calculating the charge balance without the DOM has produced the following results:

In the water an excess of cations -17.7%- was evident, whereas the beer had a cation excess of only 8%. The percentage of organic carbon in the water as part of the total anions is 3.8%, whereas the percentage of the organic carbon in the beer is 60% greater  – 6.1% of organic carbon.

3.6. Silica determination by heteropoly blue colorimetric method

The Silicon results are presented in Table 1 (page 7).

Beer: using this method caused precipitation. The precipitated form is suggested to be Molybdenum-meta-phosphate [(NH4)6Mo7O2 4(H2O)]. Therefore no silicon could be determined in the beer using this method.

As for the water, the calculated silica concentration was of 24.3 mg/L. This is in contradiction with the ICP-MS results, which suggest a concentration of 2.95 mg/L of Si. It is clear that there is a considerable difference in the results presented by the two methods.  The results produced by the ICP-MS were taken for further analysis and interpretation.

3.7. Phosphate determination by phosphomolybdate colorimetric method

The phosphate results are presented in Table 1.

Water: the concentration calculated was of 1.25 mg/L. This level of phosphate determined by the colorimatry method has a value different from the IC findings (no detected phosphate).

Beer: the phosphate precipitated with some unidentified chemical in the solution, forming a dusty blue colour. Therefore no level of phosphate concentration could be detected using this method.

3.8. Fluoride determination by specific ion electrode

The Fluoride results are presented in Table 1. Both the water and the beer had results of fluoride concentration less than 1 mg/L. The difference between the fluoride level found by specific ion electrode and by the IC has already been mentioned above under the IC results and is discussed later in this paper.

3.9. Dissolved organic carbon (DOC) determination

The DOC results are presented in Table 1. The findings suggest a significant difference between the two findings. The water has a value of 2.7 mg of carbon per liter whereas the beer proves to have 33040 mg of carbon per litre.

3.10. Ion coupled plasma – mass spectrometer (ICP-MS) determination

The ICP-MS findings are presented in Table1. The beer and the water have higher concentrations than the permitted levels in respect of a few of the elements.

The aluminium content in the beer (739 ppm) is almost 50% higher than the permitted level for domestic use in South Africa (water quality guidelines, 1995).

The concentration of chromium in the beer (622 ppm) is 12 times more than the suggested level (50ppm) by the European Union (EU) and the World Health Organisation (WHO). The South African suggested standard is for Cr6+ and therefore not comparable to the ICP-MS results which include all positive oxidation forms of Cr.

The Iron found in the beer was in a concentration of 691 ppb. The permitted level for domestic use in South Africa is 500ppm and for the purpose of an industrially produced beverage is 200 ppm.

The manganese ion is present in the beer in an excess of 15% in comparison with the permitted level for the industrial produced beverage, and an excess of 120% in comparison with the EU. The South African permitted level for Mn is 5ppm; that is a 23 fold difference from the level found in the beer (115ppm).

The levels of zinc that are found in the beer (17.5ppm) and in the water (23.4ppm) are twice as much as the permitted level for domestic use in South Africa (<10ppm).

The water source exhibits an unexpected excess of cadmium and lead in its chemical composition. This is in comparison with the suggested levels for fresh water in aquatic eco-systems in South Africa. Yet it appears to be an accepted level according to Galvin R.M. (Water S.A, Jan.1996).  The Cd level in the water sample was found to have 0.16ppb whereas the suggested level is 0.07ppb. The lead level in the water is 0.84ppb when the suggested level is 0.2ppb. It is important to note that the level permitted for human health is 10ppb. And in a similar manner to the zinc, the lead and cadmium levels can be assumed to occur in nature (Galvin, 1996)

3.11. MinteqA2 reaction path modelling

The minteqA2 was run in two different modes the results of the first mode run are presented in Table 2.

Table II     Distribution of the water components among dissolved and adsorbed species.

Component Species (%) Species (%) Species (%) Species (%) Species (%)
DOM DOM (68.2) Ca-DOM (30.7) Other  (1.1)    
PO43 H2PO4  (62.3)                                       HPO4-2  (32.4)              Ca-HPO(3.2)                 Mg- HPO4 (1.3)                   Other (0.8)
SO42 SO4-2  (95.2)                    Ca- SO4 (3.6)           Other (1.2)    
Cl Cl  (100)               
H4SiO4 H4SiO4 (99.9)                 Other (0.1)      
Mg+2 Mg+2 (97.5)              Mg- DOM (1.6) Other (0.9)    
Ca+2 Ca+2 (85.3)          Ca-DOM (13.9) Other (0.8)    
Fe+2 Fe+2 (97.8) Fe HPO4 (1.1) Other (1.1)    
Mn+2 Mn+2 (99)                   Other (1)      
Zn+2 Zn+2 (60.1) Zn-DOM (38.9) Other (1)    
K+ K+ (100)        
Na+ Na+ (100)        
Li+ Li+ (100)        
H2O OH (93.7) FeOH  (2.6) ZnOH  (1.8) Other (1.9)  
H+ H2PO4  (75.4)                                       HPO4-2  (19.6)               Ca-HPO(2)                 H-DOM (1.3) Other (1.7)

The distribution of the different species in the table presents a strong bonding between the calcium ion and the DOM and a smaller presence (few percent) of the major cations (Ca, Mg) bonded to DOM and to the phosphorus ion.

In Table 3, the saturation indices of the solution with respect to various minerals are presented in two ways. The first, when no precipitation is allowed, and the second, when precipitation is permitted for oversaturated minerals (i.e. the water being oversaturated with respect to these minerals).

Table III    Saturation indices of the water stream sample.

Mineral

Chemical  Form

Saturation  index

(No Precipitation)

Saturation  index

(Precipitation)

Chalcedony SiO2

-0.97

-0.97

Cristobalite SiO2

-0.91

-0.91

Hydrapatite Ca5(PO4)3OH

0

-0.03

Quartz SiO2

-0.48

-0.45

SiO2 SiO2

-1.48

-1.48

MnHPO4 MnHPO4

0.98

0

Comparing the two modes of saturation, it is clear that MnHPO4 and quartz have precipitated in the solution. The quantities of these solids are of a trace value (10-7).

The beer sample produces the following results, represented in Table 4 as the distribution of the beer components.

Table IV   Distribution of the beer components among dissolved and adsorbed species.

Component Species (%) Species (%) Species (%) Species (%) Species (%)
DOM DOM (54.5) Ca-DOM (24.1) H-DOM (14.7) Mg-DOM (4.3) Al-DOM (2.3) Other  (1.1)
PO43 H2PO4  (89.3)                                       Mg-H2PO4+ (6.7)       Ca-H2PO(2.9)                  Other (1.1)  
SO42 SO42  (71.7)                    Mg- SO4 (15.5) Ca- SO4 (3.6)           KSO4 (2.2)                         Other (1.2)
Cl Cl  (100)               
NO3  NO3  (100)                  
H4SiO4 H4SiO4 (100)                      
Al+3 Al-DOM (85.6)  Al+3 (11.1)                      Al SO4+    
Mg+2 Mg+2 (86.5)              Mg-H2PO4+ (6.7)       Mg- SO4 (5.8) Other (1)  
Ca+2 Ca+2 (81)          Ca-DOM (7.8) Ca- SO4 (6.2)           Ca-H2PO4+  (4.9) Other (0.8)
Fe+2 Fe+2 (44) Fe H2PO4  (52.3)  Fe SO4 (2.9)                    Other (0.8)  
Mn+2 Mn+2 (93)                  MnSO4 (6.3)              Other (0.7)    
Ba+2  Ba+2 (86.8)            Ba-DOM (13.2)      
Cr+2  Cr+2  (100)                 
K+ K+ (100)        
Na+ Na+ (100)        
NH4+  NH4+ (99.1)            Other (0.1)      
Cu+ CuCl2 (74.5)                        Cu+  (24.9)                 Other (0.6)    
H2O OH (93.7) FeOH  (2.6) ZnOH  (1.8) Other (1.9)  
H+ H2PO4  (75.4)                                       HPO42  (19.6)               Ca-HPO(2)                 H-DOM (1.3) Other (1.7)

The DOM has a significant effect on the variety of species present in the beer solution. The amount of elements bonded to DOM increased in 66% in comparison with the water.

Chloride, Sodium and potassium ions are the only elements that had not gone through any changes in their speciation, Both in the water and in the beer.

In Table 5 the different saturation indices of the beer are presented.

In a similar manner to the water, it is suggested that quartz and MnHPO4  precipitate under the conditions presented in Table 1  (page 7).

Table I     

Table V    Saturation indices of the beer.

Mineral

Chemical Form

Saturation index

(No Precipitation)

Saturation index

(Precipitation)

Alunite Kal3 (SO4) 2 (OH) 6

-0.006

-0.006

Anhydrite CaSO4

-1.4

-1.4

Barite BaSO4

-0.16

-0.16

Chalcedony SiO2

-0.14

-0.49

Cristobalite SiO2

-0.08

-0.42

Diaspore AlO(OH)

-0.37

-0.37

Gypsum CaSO4 · 2H2O                   

-1.17

-1.17

Quartz SiO2

0.35

0

SiO2 SiO2

-0.65

-1

Kaolinite Al2Si2O10 (OH) 2

-0.03

-0.72

Pyrophyllite Al2Si4O10 (OH) 2

0.06

-1.32

MnHPO4 MnHPO4

1.69

0

4. Discussion

In this study two related water samples are compared: a water stream sample taken from the Newlands stream and a “Castle” beer sample manufactured at the SAB plant in Newlands. During the making of the beer, the water goes through intensive chemical and physical treatment. The outcome – a beer – is significantly different in its chemical nature in comparison with its major source – the water stream. Yet, it is possible to compare (the two samples) in almost every aspect.

Each of the samples is discussed separately and evaluated in comparison with a similar environment, and the related quality standards.

The extensive difference in the pH values is evident and is to be expected bearing in mind that the water has gone through an intensive industrial procedure.

The results can be challenged by different means of interpretation. To begin with, the eluent used for the anion detection in the IC method (1.8mM Na2CO3 + 1.7mM NaHCO3) is characterised by a close detection time for fluoride chloride and nitrite. Furthermore, the fluoride is the first anion to appear in the analysis and therefore may carry with it some impurities from a previous sample. A different eluent might be able to produce a better separation of the elements, especially when a significant amount of organic matter may be present in the analysed sample (such as the beer). The organic acids overlap some of the

Elements, such as fluoride and chloride and cause an artificial increase in the final report that the IC produces. This problem may be the reason for the uneven baseline that appears in the beer IC analysis. Organic acids, such as Oxalate and Acetate can overlap anions such as fluoride and thus cause the problem described above.

4.1. Water analysis

The pH value of the water (6.86) is within the required standards of the South African Department of Water Affairs – Water quality guidelines. There is more than a one order of magnitude difference in the pH level between the results produced in this report and a water analysis done in October 1997 for the same water stream (Muller J. 1997). The latter presents a pH level of 5.5 for the spring water. The reasons for this difference may lie with the fact that DOM and the organic acids (in particular), that are present in the water can affect pH determination and cation-anion balance (Murray & Wade, 1996).

To elaborate on the different findings of the October analysis and the present one, a comparison is presented in Table 6 (page 14).

Table VI   A comparison of the Newlands water spring during the summer of 1997/8

Method

October 1997  analysis

February 1998 analysis

pH

5.5

6.86

EC mS/cm

191

174

Alkalinity mg/l (HCO3 )

19

0

 

mg/L

mg/L

Ca

2

13.3

Mg

3

2

Na

16

16.3

K

1

1.4

Zn

0.01

0.02

Fe

0.02

0.06

Mn

0.01

0.01

Cu

<0.01

<0.01

Cl

35

35

SO4

<5

5.8

NO4

6.22

Bdl

NO4

<0.01

Bdl

F

0.03

<1

Si

2.2

2.95

It can be noticed from Table 6 that the presence of the major ions in the water did not change.

There is, however, some difference in the calcium and the alkalinity levels. The latter can, perhaps, be explained by seasonal fluctuations. The water may be influenced by early summer rains and thus include high levels of carbonates washed into the water. However, there is a contradiction. The low calcium levels that are presented in the October analysis do not completely match the above suggestion. Further observation should be conducted concerning the seasonal cycles of the major elements in the water spring.

Studying the output of the elements in the water has produced the following observations:

Firstly, the organic matter present in the solution plays an important role in the water speciation. It can be noticed that without considering the DOM, the overall ion charge is not balanced, with an excess of cations (15%). On the other hand, adding the total DOM concentration creates a 69% excess of anions. This refers to just 2.7 mg/L of organic carbon, present in the water solution.

Secondly, the minteqA2 analysis results suggest that quartz and MnHPO4 precipitate in the water. This phenomenon is unlikely to happen since the samples were taken from the water stream where any precipitating elements present would not appear in the aqueous phase, unless, they are present as suspended solids. This finding may suggest that there is some mechanism (biological, gas pressure) that preserves the water in oversaturated levels in respect of quartz and MnHPO4.

The South African water quality guidelines suggest some target levels for the different

elements and species present in the solution (Table 1).

It is clear when comparing the guidelines with the findings of this report that the Newlands water spring does not meet the necessary limitations.

However, there are some influencing factors that must be considered. The relatively nearby Atlantic Ocean might influence the water spring through ground water (rain, salt leaching, contact of the afriatic line). Thus, sodium and chloride concentrations in the spring will never meet the required guidelines.

The presence of trace elements, such as aluminium, zinc, cadmium and lead are found in levels above the targeted guidelines for aquatic eco-systems (Table 1).  Aluminium is an abundant element, and therefore can be expected to be present (<10 ppb) in such a water system.

The reason for the presence of zinc cadmium and lead is not very clear. Cadmium can be related to zinc through different minerals such as greeockite (Galvin R.M., 1996). Furthermore, the higher the presence of organic matter – the lower is the expected level of cadmium. Since the water has low levels of organic matter (2.7 mg/L of carbon), the presence of cadmium in the water stream is not unexpected. The lead levels meet the naturally occurring levels presented by Galvin R.M. (Water SA, Jan 1996), if they do not exceed 10 ppb.

4.2. Beer analysis

This artificial beverage has a very complex chemical nature. In Table 7 (page 16) the writer indicates the influence of different elements and chemical characteristics on some of the unwanted phenomenon in an industrial process.

The table presents a complex interaction between the different influencing factors. They are not to be discussed here but presented in order to exemplify the role the different elements play in the process of making a beverage.

The pH of the beer (4.25) can be attributed to a number of factors;

  • The process of fermentation. Natural yeast nutrients, such as phosphoric and lactic acids are released  and may acidify the water (King, 1993). Adding hop acids acts as a potent anti-microbial (Baxter, 1998). Acid washing for bacterial infection (Miller, 1998).
  • Adding nutrients such as sulphur, chloride and phosphorus is a common practice for taste regulation of the product (SAB, 1997; Thomas, 1998). The addition of salts (calcium, epsom, chloride, phosphate and sulphate salts) to the process of beer making is necessary (King, 1998). Thus, we expect the EC levels of the beer to be relatively high. The TDS value, consequently, will have a high value. The level of alkalinity differs in the various makes of beer (SAB, 1997). A low level of alkalinity is expected in very low pH (<5). Nevertheless it is important to recall that the water source that serves in the making of beer has, on its own, a low level of alkalinity.

Table VII   Constituents that contribute to problems in an industrial process.

The Water Affairs requirements for the manufacture of beverages in industry are presented in Table 1. The levels required are under category 2 of the proposed water quality draft (1995). This category specifies beverages under the sub-category of water product. The results of the beer analysis do not meet some of the requirements for a water product in the making of a beverage.

Potassium is present in the beer (331 mg/L) at a level, which is more than six times the permitted level by the water guidelines (<50).

Magnesium (127 mg/L), as well, is present at a level of 80% more than is allowed (<70 mg/L).

The sulphate level in the beer (188 mg/L) is more than twice as much as the levels specified by Water Affairs (0-80 mg/L). The reason for this high level may be in the process of manufacturing the beer (adding sulphate salts).

The iron present in the beer (691 ppb) is 2½ times higher than the suggested level (0-200 ppb). There is no apparent reason for the high levels of iron in the water, unless it was added for reasons of flavour. (Iron adds a metallic flavour.)

Another influencing factor is the method in which the iron was analysed – the ICP-MS. In using this method with the specific machinery used for this analysis there is room for a miscalculation of the iron content. The ICP system can produce a result which is higher (to an unknown extent) than the actual concentration.

The manganese is 15% higher (115 ppb). There is no apparent reason for the high levels of manganese in the water. Unless, as in the case of iron, it was added for flavour purposes.

The Water Affairs document for water quality in industry is incomplete in its coverage of the various constituents in water and therefore not all the beer constituents could be compared properly. There is a brewing guideline (Allen, 1998) that has suggested the following limits and average levels of elements in the beers.

The limited levels of the various elements presented in Table 8 (page 17) are different from the levels presented by the Water Affairs guideline. Therefore, this might change the perspective in which the quality of the beer liquid is examined. For example, an element such as aluminium or calcium might seem to be at a level permitted by the Allen guideline (Table 9). Yet, its level in the Water Affairs guideline (Table 1), might be health affecting. Williams (online, 1998) suggests that the average daily intake of aluminium is 3.9 mg, whereas, a beer bottle containing (by average) 100mg/L will contribute 0.3 mg of aluminium. Water may add up to 0.2 mg per day (Williams, 1998).

Table I     

Table VIII  Limiting & average levels of factors influencing the quality of beer (Allen, 1998)

Factor

Limit     mg/L

Average    mg/L

Alkalinity     

None

<19.6

Aluminium 

None

<0.07

Arsenic

0.05

<0.007

Barium

1

<0.097

Cadmium

0.01

<0.002

Calcium

None

6

Chloride

250

3.2

Chromium

0.05

0.017

Copper

1

0.05

Fluoride

1.4-2.4

0.121

Iron

0.3

0.08

Lead

0.05

0.009

Magnesium

None

3.15

Manganese

0.05

0.011

Nitrate

10

0.22

pH

None

7.1

Potassium

None

0.73

Sand

2

0.8

Selenium

0.01

0.002

Silicon

None

16.13

Another trace element present in an unwanted level is chromium. The beer consists of 622 ppb of chromium. It has a beneficial action in the form of protein uptake by cells. Yet, low levels of Cr6+ uptake and high levels of Cr3+ uptake may promote health problems (Galvin, 1996), of which some are severe in the long term (cancer).

Since the ICP-MS detects all positive oxidation states (in the case of chromium- +2, +3, +6), it is clear that the concentrations of chromium do not specify the various oxidation states, and full understanding of the Cr analysis is impossible.

The minteqA2 speciation module is presented in Table 4. From the minteq speciation a few conclusions may be offered. The DOM present in the beer is bonded to many elements (Ca, Mg, Al, Ba, H). It is an anticipated result, due to the high affinity of organic matter to cations and its high surface area that enables a high adsorption ratio. Species such as SO4, H2PO4 are present in a familiar level according to the beer pH level and as compared with equivalent distribution of species (Murray & Wade, 1996).

The mineral indices of beer presented in Table 5 (page 12) suggest that quartz and MnHPO4 may precipitate. This occurrence is unlikely to happen, as in the water, since the samples were in an aqueous phase. However, it may be possible that these minerals exist in the beer as suspended colloids. Their presence is, in any event negligible since their concentration is in a trace quantity level.

4.3. MinteqA2  hypothetical scenario

4.3.1. Water salinisation

 MinteqA2 was run according to the following scenario: salinisation of ground water, due to acid rain, or intrusion of the afriatic boundary into the underground aquifer. Hence, the concentration of sulphate has risen to a level of 100 mg / L. The concentrations of chloride and sodium are not likely to influence the solution in this particular scenario. This is especially so, since it was noticed in the original mionteqA2 run (Table 2) that the speciation of the two elements did not change. Consequently the chemical composition of the water has changed. The changes are expressed in Table 10 (page20) where the distribution of components in the solution is described. The results of the hypothetical monteq run are presented in Table 9 (page 19).

To begin with, the pH level has risen to 7.3. Next, the total charge balance changed to an excess of 38 % of anions – an anticipated result. The minerals that may precipitate are Hydrapatite, MnHPO4 and ZnSiO3.

It is clear from the table that some significant changes occurred in the water.  The excess of sulphates had quite a distinctive influence on some of the species.

The phosphate speciation has changed. The ratio between HPO42 and H2PO4 has changed. This is in correlation with the behaviour of the species described in the literature (Murray & Wade, 1986). Yet, the percentage of change in the ratio is more than is described in the literature. The scenario test-run presents a 100% increase in the HPO42 concentration and a 50% decrease in the H2PO4 concentration, whereas Murray & Wade suggest not more than a 15% change for both species. This immense change in the ratio can perhaps be explained by the charge imbalance. It is clear that a missing cation can influence the speciation of a solution by its absence.

Table IX        Distribution of the water components among dissolved and adsorbed species.

Component Species (%) Species (%) Species (%) Species (%) Species (%)
DOM DOM (70.9) Ca-DOM (28.1) Other  (1)    
PO43 H2PO4  (35.8)                                       HPO4-2  (57.3)              Ca-HPO(4.3)                 Mg- HPO4 (1.8)                   Other (0.8)
SO42 SO4-2  (96.3)                    Ca- SO4 (2.7)           Other (1.0)    
Cl Cl  (100)               
H4SiO4 H4SiO4 (99.8)                 Other (0.2)      
Mg+2 Mg+2 (89.3)              Mg- DOM (1.5) Mg SO4  (9.1) Other (0.1)  
Ca+2 Ca+2 (77.5)          Ca-DOM (13.4) Ca- SO4 (9)           Other (0.8)  
Fe+2 Fe+2 (90.2) Fe SO4 (9) Other (0.8)    
Mn+2 Mn+2 (90.3)                  Mn SO4 (9.4) Other (0.3)    
Zn+2 Zn+2 (54.2) Zn-DOM (37.2) Zn SO4 (7.3) Other (1.3)  
K+ K+ (99.5) Other (0.5)      
Na+ Na+ (99.6) Other (0.4)      
Li+ Li+ (99.7) Other (0.3)      
H2O OH (95.3) FeOH  (2.3) Other (2.4)    
H+ H2PO4  (54.5)                                        HPO4-2  (43.6)              Ca-HPO(3.3)Mg HPO(1.3)                 H-DOM (3.3) H+ (1.4)           

As for the sulphate species concentration in the solution, it has not changed in a meaningful manner. This may be predicted since the sulphate does not react strongly with sodium to create a salt.

The sulphate had an effect on the zinc and manganese speciation. These two elements (Zn, Mg) were not bonded before to sulphate. However, under the new circumstances they have each spared 10% of their concentration to a combined species with sulphate.

4.3.2. Beer acidification

 

The scenario for the minteqA2 test-run is as follows: an unplanned acidification has increased during the mash fraction in the beer manufacturing process. The assumed pH is 3.5 (the final product is 4.25).

The overall charge balance has changed. An excess of 31% in cations is present in the solution. This may be explained by the precipitation of diaspore and removal of hydroxyls from the solution. Precipitation of quartz, MnHPO4, diaspore and hydrapatite is anticipated in trace levels 10-4M to 10-6M.

The concentration of H2PO4 has risen by 3-fold to 4.6 10-3 M. This rising in the phosphoric acid concentration can be predicted, according to the phosphorus speciation behaviour in different pH levels that presents such a pattern of behaviour (Murray & Wade, 1986).   The beer solution speciation is introduced in Table 10 (page20).

A few changes in the solution speciation are evident. The DOM speciation was changed. It has become more susceptible to other species (H+ in particular). Barium is now attached as well to DOM.

An interesting development is the speciation of potassium sodium.  In the original speciation (Table 4), they were not effected. Here they are effected to a minor degree (<1%). The potassium is bonded to the sulphate, yet the sodium is not specified. It can therefore be assumed that the sodium and the ammonium are bonded to other species, which are probably in small quantities (<1mM).

The hydroxyl speciation has changed in a significant manner. Most of the OH (99.9%) is bonded to aluminium, Whereas before the OH was mostly specified as OH and a minor percent was bonded to Fe and Zn. The reason for this may lie with the increasing solubility of aluminium in decreasing pH levels.

The phosphorus, as may be predicted, changed its speciation slightly. A new species is added to the solution – H3PO4 (3.1%).

Table I     

Table  X   Distribution of the beer components among dissolved and adsorbed species.

Component Species (%) Species (%) Species (%) Species (%) Species (%)
DOM DOM (45.9) Ca-DOM (11.7) H-DOM (38.4) Mg-DOM (2) Al-DOM (2)
PO43 H2PO4  (87.2)                                       MgH2PO4+ (6.6)       Ca-H2PO4 +(3)                 H3PO4 (3.1)                     Other (0.1)
SO42 SO4-2  (70.6)                    Mg-SO4 (15.3) Ca- SO4 (10.1)           KSO4 (2.1)                         HSO4 (1.3)                      Other (0.6)
Cl Cl  (100)               
NO3  NO3  (100)                  
H4SiO4 H4SiO4 (100)                      
Al+3 Al-DOM (74.3)  Al+3 (21)                       Al SO4+ (4.2)                   Other (0.5)  
Mg+2 Mg+2 (87.3)              Mg-H2PO4+ (6.6)       MgSO4 (5.7) Other (0.5)  
Ca+2 Ca+2 (84.9)          Ca-DOM (3.8) CaSO4 (6.4)           Ca-H2PO4+  (4.9) Other (0.8)
Fe+2 Fe+2 (45.2) Fe H2PO4  (51.8)  FeSO4 (2.9)                    Other (0.1)  
Mn+2 Mn+2 (93.1)                  MnSO4 (6.2)              Other (0.7)    
Ba+2  Ba+2 (93.4)            Ba-DOM (6.6)      
Cr+2  Cr+2  (100)                 
K+ K+ (99.5) Other (0.5)      
Na+ Na+ (99.6) Other (0.4)      
NH4+ NH4+ (99.1)            Other (0.1)      
Cu+ CuCl2 (74.5)                        Cu+  (24.9)                 Other (0.6)    
H2O AlOH (96.7) Al(OH)2 (3.2)        Other (0.1)    
H+ H2PO4  (80)                                       H3PO4  (4.3)              Ca-H2PO(2.7)   MgH2PO4+ (6)             H-DOM (3.4) H+ (3.3)          Other (0.3)

5. Conclusions

The Newlands water spring and “Castle” beer samples analysed from a geochemical point of view, during the course of this study have revealed two major findings.

In relation to aquatic eco-systems and domestic use – the water stream has proved to have adequate standards. In relation to domestic use and artificial beverage production –  inadequate levels of certain elements were found in the beer sample.

5.1. Newlands water spring sample

The chemical characteristics of the water solution present a high quality standard, even though elements such as zinc and manganese are present at levels that are above the limits permitted for aquatic eco-systems and domestic use by the South African water quality guide (1995). This may be explained by the natural occurrence of these elements in the surrounding environment.

A considerable increase in the salinity of the solution (100 mg/L sulphates) can create a significant change in the speciation of the solution. This change might influence the production of the beer. Though, salinity may not necessarily prevent the use of the water for beer production since salts, in any case, are added to the water.

5.2. Mediating process

Once the water is inserted in to the process of beer manufacturing, it goes through a substantial change in its overall chemical speciation and characteristics. The pH is dropped from 6.86 to 4.25, and salts are added in hundreds of mg/L for the purpose of taste regulation. Thus, the final product – beer – is of a completely different chemical and physical nature than its primary source – the water spring.

5.3. “Castlebeer sample

The beer itself presents a chemical structure that is a derivative of its manufacturing process. Hence, it is bound to be quite different from the water source. This big difference is mainly due to the salinisation of the solution (for reasons presented in section 5.2.).  Yet, inspite of this controlled salinisation of the solution the analysis results present a solution quality that does not meet the water quality guidelines for industrial use. That is for category 2 – the manufacture of a beverage (South African Water Affairs-water quality guide, 1995).

Major elements such as potassium, calcium and magnesium are present at levels that are more than four times higher than the permitted levels. Trace elements such as aluminium, chromium, iron, manganese and zinc are present in concentrations considered by the South African water quality guidelines and by the EU as above the permitted levels. The concentrations of iron, chromium and aluminium should be given serious examination, since they may be present in health affecting levels.

An unintentional change in the pH of the solution during the process of the beer manufacturing may result in a different chemical speciation. The effects and results of such a hypothetical change are to be evaluated in a food technology perspective.

 

6. REFERENCE

Baxter D. (1998). Beer is good for you – discussion. Online, BreWorld.com

Clesceri et al. (1989). Standard methods fot the examination of water and waste water. 17th ed.

American Health Association: Washington D.C.

Drever J.I. (1997). The geochemistry of natural waters. 3rd ed. Prentice Hall: N.J.

Galvin R.M. (1996). Occurrence of metals in waters: An overview. Water SA. Vol. 22 No. 1. pp 7-18.

Lanyon R. (1996). Chemical analysis of water samples from Rietvlei and Diep river, Cape Town. .

Unpublished report, Dept of geological sciences, U.C.T.

Miller D. (1998). Demystifying water analysis tables. Online,

http://breweingtechniques.com/library/backissues/issue1.1/miller.html

Muller J. Laboratories (PTY) LTD. (1997). Newlands water spring.  analysis report. p.6

Murray K., Wade P. (1996). Checking anion-cation charge balance of water quality analysis: Limitations        of the traditional method of non-potable waters. Water SA. Vol. 22 No. 1. pp 27-32.

Nowicki T.E. (1997). The impact of plantations of Pinus spp. On the chemical properties of soils and stream waters 

             in South African Upland Catchmants. Unpublished Ph.D. thesis. Department of Geological sciences.

University of Cape Town.

Republic of South Africa – Office of Water Affairs and Forestry (1995). Water quality guidelines,               

Vol. 1 Domestic use.

Republic of South Africa – Office of Water Affairs and Forestry (1995). Water quality guidelines,               

Vol. 3 Industrial use.

Republic of South Africa – Office of Water Affairs and Forestry (1995). Water quality guidelines,               

Vol. 7 Aquatic Eco-systems.

South African Breweries. Untitled. An overview of water quality for beer production. Internal publication.

Thomas K. (1998). The role of Sulphur. Online, BreWorld.com

Van Tienhoven A.M. (1996). Report on groundwater analysis from the world of birds wildlife sanctuary,

Hout-Bay. Unpublished report, Dept of geological sciences, U.C.T.

Williams D. (1998). Aluminium in beer. Online, BreWorld.com

King K. (1998). Water treatment: Philosophy, Approach and Calculations. Online,

http://breweingtechniques.com/library/backissues/issue1.3/king.html

7. Appendix A:      Analytical methods

7.1. Determination of electrical conductivity  – EC.

The electrical conductivity of each sample was determined using a CRISON microCM 2201 conductivity meter at room temperature. Conductivity values are expressed in Siemens per unit distance (usually – mS/cm).

7.2.  Determination of pH values

Determination of pH (- Log aH+) was achieved using a CRISON micropH 2001 microprocessor controlled pH meter at room temperature. The meter determines hydrogen ion activity electrometrically using a combined glass indicator-reference electrode.

7.3. Determination of Alkalinity

Alkalinity was measured using the method of Gran titration. Stepwise titrations are carried out using a radiometer ABU80 autoburette and TTT85 titrator. A sample volume of 10ml was used and titrations were performed using 0.01HCl.

The principles and application of this method were taken from the unpublished Ph.D. thesis (U.C.T.  1997) by Mr. Tom Nowicki  (pp. 195-197).

The volume of the acid added is plotted against a function of the added volume – Fx. In Figure 2 the Gran titration method is presented:

-0.02 pH 3.2 FpH 3.8 pH 4 0                        vVx

Figure 2: Alkalinity determination using Gran titration.

The parameters involved in the calculation of alkalinity are:

Fx = Ca (vf – vx) = -10pHx (vs+ vx).

Ca = the normality of the strong acid used.

vf    = the volume of a strong acid (ml) required to bring the sample to the H2CO3

equivalent point.

v= volume (ml) of acid added at the titration.

vs  = the volume (ml) of sample used for the titration.

Table A1.3 presents the calculations done using Microsoft Excel, to determine the alkalinity.

For the purpose of the calculation vwas determined by extrapolation of the linear portion of the function to the intercept on the vx axis (Fx = 0).

Table 11   Alkalinity calculations for water stream sample.

MQ water

Water stream sample

Vol.  ml pH f(x) Vol.  ml pH f(x)
10.3 5.35 -4.6exp-5 10.3 7.39 -0.4exp-6
10.444 4 -1.1exp-3 11.109 4 -1.2exp-3
10.53 3.8 -1.8exp-3 11.196 3.8 -1.8exp-3
10.651 3.6 -2.7exp-3 11.345 3.6 -2.9exp-3
10.872 3.4 -4.43exp-3 11.592 3.4 -4.62exp-3
11.219 3.2 -7.1exp-3 12.006 3.2 -7.58exp-3
Vf = 0.01 Alk = 9.7exp-6 Vf = 0.02

Alk=1.94*105-9.7*106=9.7*106

 CaCO3  = 9.7exp-4 mg/l CaCO3  = 9.7 exp-4 mg/l

Alkalinity is than determined by the following equation: Alk = (vf – Ca) ¸vs.

It is important to note that no calculations were done for the beer sample. That is due to the fact that below the level of pH 6.3 the concentrations of CO32 and OH are negligible.

7.4.  Cation and anion measurements using Ion Chromatography.

Cation (K, Na, Ca, Mg, NH4, Mn & Li) and anion (Cl, F, NOx, PO4, SO4 & Br) concentrations within the water samples were determined by an HPIC-AS4A separator. The samples were initially filtered through a 0.45mm Millipore filter membranes to remove suspended solids. Than diluted with Milli-Q water to obtain EC levels less than 100 mS/cm.

The lower limit of detection for most ionic species that can be measured by IC is within the ppb range.

Evaluating the IC results should be done carefully. Double peaks are due to unidentified elements in the solution as well as elements which their readings are very near one to another and the overlapping can cause a misinterpretation of the results.

Table 1 of the report (page 7) presents the data obtained from the IC analysis.

7.5. determination of phosphorus – P – concentration

Phosphorus concentrations were determined using the phosphomolybdate colorimetric method, as described in Standard Methods (1989). This method can be used to analyse most natural, industrial and sewage type water samples.  A phosphate reagent solution is prepared from ammonium molybdate, ascorbic acid, antimonyl potassium tartrate and sulphuric acid. The reagent is added to a blank, a standard and the sample. After 10 min. the absorbance of the blank, the standard and the sample are measured.

Beer sample–  precipitated with some chemical in the solution to form a dusty blue colour solution. Therefore the concentration of the phosphate in the beer could not be determined.

Water sample– the  absorbance was detected at 0.029.  Extrapolation from the calibration graph suggests that the concentration of the Phosphate is 1.25 mg/l. or 0.04mM/l. Figure 3 describes the determination of phosphate in the water sample.

Figure 3: phosphate determination in the water stream sample.

 

7.6.  Determination of Fluoride

Fluoride ion was determined through a selective electrode method. This method suites fluoride (F-) concentration from 0.1 to more than 10 mg/L. Some elements interfere with the ion determination. Aluminium and Chloride ions are decreasing factors in regard with the fluoride concentration determined.

7.7.  Determination of Silica

The Silicon ion tested is the soluble silicon with no reference to the monomers and colloidal properties. Silica concentrations were determined using the heteropoly blue method (standard methods, 1989).

Procedure – HCl and ammonium molybdate reagent are added subsequently to the samples and to a set of standards. Later oxalic acid is added and the solution is mixed. An absorbance reading is taken between 2 – 15 min. No NaHCO3 digestion was used. If necessary a dilution of the samples must be made, in order to make it comparable to the standards and a blank. Finally the Silica (in grams per 55ml of final volume) is plotted against the absorbance. Figure 4 represents the silica determination in the water stream sample.

Figure 4: Silica determination of the water stream sample.

  7.8.   Inductively Coupled Plasma – Mass Spectrometer, ICP-MS.

              Method of trace elements determination.

A quantitative analysis of trace elements was conducted by ICP-MS. The make of the system used was of an Elan 6000 by Perkin-Elmer Sciex, U.S.A.  It is a system consisting of three major components: and inductive coupled plasma (ICP) source, a quadropole mass spectrometer (MS) and an interface that links them. The ICP provides the source of the ions from the sample being analysed. The MS permits detection of ions at each mass in sequence. The electrical signals resulting from the detection of the ions are then processed into a digital information system that is used to indicate ion intensity and subsequently the ion concentration.

Interference –

Spectral interference – ions other than the desired analyte ions appear in the

spectrum of analysis. For example Iron determination can easily be disturbed by the presence of the Ar ion in different oxidation states (+1, +2)

Isobaric effects – the presence of isotopes influences the determination of the desired

ions, and thus overlapping of one element by another can occur and create a false

increase of the examined element’s peak.

Matrix effect – the TDS must be kept beneath the level of 0.1 g/ 100 cm3 to minimise

clogging of the system.

To conclude, it is a system that requires a highly skilful operational ability and a careful measure in the preparation of the samples.

For the purpose of this report, the samples were filtered through a 0.45mm Millipore filter and then diluted to a level below 100 ms/cm.

7.9 Determination of the dissolved organic carbon – DOC.

Organic carbon is oxidised to carbon dioxide, CO2, by persulphate in the presence of ultraviolet light. The CO2 produced may be measured directly by a nondispersive infrared analyser, be reduced to methane and measured by flame ionisation detector, or be chemically titrated. The minimum detection level is 0.05 mg/L of organic carbon.

Interference – this method is highly sensitive to any slight change in the composition of the air. Any change in the concentration of CO2 in the air will influence the DOC determination, thus if no precautions are taken. Contamination during handling the organic carbon sample is a likely source for an error. The samples are filtered through a 0.45 mm Millipore filter membrane to remove suspended solids. Thus some of the organic carbon present in the dissolved organic matter will not be calculated due to its filtering out.

7.10. MinteqA2 reaction path modelling.

The MinteqA2 is a geochemical equilibrium speciation program developed by the U.S. Environmental Protection Agency. This program produces a successive composition of a solution as a mineral (or several minerals) reacts with the solution or as some other process, such as precipitation, proceeds.

An input file is prepared using data such as temperature, pH and the concentrations of the different elements present in the solution. The file is run through the minteqA2 program and an output file is produced.

The minteqA2 program enables a variety of calculations. Changing pH, temp, concentrations and other chemical characteristics enables to evaluate hypothetical possibilities for the examined solution.

8. Appendix B:    Group results

8.1. Analysis results

The samples collected by the group were taken from various places in the Cape region. The analyses results are presented in Table 12 (page 29). Some of the locations from which samples were taken can be considered to be pristine, i.e., matching a natural environment. However, some of the samples were selected from polluted sites, either in natural environments (rivers) or from anthropogenic sites (fertiliser ponds, Vlei’s, etc.).

8.2. Interpretation and discussion

It is a common practice in soil science to calculate the sodium adsorption ratio for agricultural and engineering purposes.  In this report an attempt to analyse the sodium adsorption ratio is undertaken. Although the samples are taken from various water systems, the water is originally from a soil environment. Thus, a careful assumption can be taken that these water samples reflect the nature of the soil solution, to a certain extent (which is unknown).

In Figure 5  the concentrations of sodium (mg/L) and the SQRT [(Ca+Mg)/2] ratio were compared.

Figure 5   SAR interpretation of the group results

It is important to note that two samples were excluded. The first, is the beer sample. It is an artificial beverage, and thus, comparing it’s SAR to that of a natural system is not practical. The second sample to be excluded is the sample taken from the Cape Point Nature Reserve pond. This pond is likely to be under a strong influence from the nearby Atlantic Ocean and therefore can be expected to include high levels of sodium. Such a high level of sodium is common only in highly saline soils, that would have quite a different chemistry and characteristics from other soils. Therefore it was excluded from this analysis.

It is evident from Figure 5  that a strong correlation (R2=0.977)exists between the sodium and  calcium + magnesium. The implications of such a comparison may suggest that the water systems do in fact maintain some of the soil solution nature and, perhaps can be treated as such. Yet it is clear that this is just a primary assumption and a further analysis should be done.

A further attempt to analyse the results was done. The ratio between SAR and EC is known in soil science to have a linear correlation. In the group results there seems to be no linear correlation between the SAR and the EC. This might suggest that the initial analysis of the group results done for  SAR may not be correct and its interpretation may be wrong.

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