ATTACHMENT13
NATSRV 4: Water and Wastewater
Management in the Dairy Industry
Report to the
Water Research Commission
By
M. Chimonyo, I.V. Nsahlai
Animal and Poultry Science, School of Agricultural, Earth and Environmental Science, University of
KwaZulu-Natal, Pietermaritzburg
WRC Report No:
ISBN:
DISCLAIMER
This report has been reviewed by the Water Research Commission (WRC) and approved for
Publication. Approval does not signify that the contents necessarily reflect the views and policies of
i
the WRC, nor does mention of trade names or commercial products constitute endorsement or
recommendation for use.
ii
Executive Summary
The increasing demand for fresh water, changes in the type of products, technologies used and size of dairy
companies requires accurate estimation of the water use, extent to which water is conserved and recycled.
The objective of the project was, therefore, to determine water conservation strategies for different sizes of
companies across the different provinces of South Africa. Dairy companies were categorized into small,
medium and large based on the volume of milk they receive per month. Out of 233 dairy companies, 103
were willing to participate in the project. A structured questionnaire was used to collect data. Pollutant loads
were estimated from selected companies in KwaZulu-Natal, Gauteng, Eastern Cape, Western Cape, Free
State and Limpopo provinces. Effluents were collected during the end stage of each production. Effluents
were classified according to treatments (size of company and production) and control (fresh water).
Chemical oxygen demand (COD), total suspended solids (TSS), nitrates, chlorides, colour, pH, dissolved
calcium, dissolved magnesium, fluoride and sulphate concentrations, total dissolved solids, total hardness,
turbidity (NTU) and total coliforms of these effluents were estimated.
Western Cape, Gauteng and KwaZulu-Natal were the biggest processors of milk. The most common
products on the market are pasteurised milk, cheese, yoghurt, sour milk, fruit juice blends, fruit juice and ice
cream, in that order. Cultured products (yoghurt and sour milk) were mostly produced by large companies. A
bulk of these companies used municipal water, followed by borehole water. High volumes of water are used
during receiving, steaming, filling and cooling. A majority of these companies (84 %) indicated the need for
conserving water.
The amount of water (in millions of litres) used to process these volumes of milk are 2867, 4008 and 2259 for
cheese, fresh milk and milk powder/butter fat, giving a total of 9.2 million m 3 of water. The wastewater (in
millions) million that is generated from cheese, liquid milk (fresh and cultured) and dry by-products (milk
powder and butter) was estimated to be 852, 77.5 and 436 m 3/ year. The estimate was generated from the
knowledge that milk contains 87.5 % water. The total effluent generated is, therefore, the sum of 1 365 and
9 135, which gives 10 500 million m3 per year.
There were 61 % companies that did not treat water before disposal. Using wastewater for irrigation was the
most adopted water conservation strategy used followed by recycling (particularly for cleaning) and water
pinch. The water conservation strategies used were similar among different company sizes and across
provinces.
Colour of effluent, dissolved calcium, dissolved magnesium, fluoride, pH, TDS, total hardness and total
coliforms were high in small companies. The chemical oxygen demand (COD), suspended solids,
nitrate/nitrite and turbidity were, however, similar among all sizes of companies. Effluent pH was lowest in
medium-sized companies. Effluent treatment reduced pollutant loads except for suspended solids, fluoride
i
concentration and pH. All pollutant loads from different provinces were similar, except that fluoride
concentrations were highest in the Eastern Cape and Gauteng, followed by KwaZulu-Natal and Limpopo.
The Free State had the least fluoride concentrations.
Pollutant loads were also influenced by the type of product. Milk, yoghurt and sour milk produced effluents
with high concentrations of suspended solids, total hardness, chloride and fluoride. Dissolved calcium
concentrations were high in effluent from cultured products. High levels of nitrate concentrations were
observed from yoghurt and fruit juices. Total coliform counts were high from yoghurt, mass, milk and fruit
blends. The pH, dissolved magnesium and turbidity were also high in yoghurt, cheese and milk products.
It can be concluded that the size of the company and the type of product affect pollutant loads. Small
companies had higher amounts of concentration. Companies should be encouraged to recycle water.
ii
Acknowledgements
We thank the management of all the companies who took their invaluable time to complete the
questionnaires. We also thank the companies that went further and provided samples for laboratory
analyses. Those companies that explained to us processes followed in the manufacture of different products
are also acknowledged.
We acknowledge the participants to both the inception and feedback workshops. Their inputs have been
invaluable, and will, forever, be cherished. We also thank the postgraduate students who collected data. Mr
Nhlakanipho W. Sithole did a wonderful job of persuading the management of the various companies to
complete the questionnaire. He also travelled across the country to collect samples.
We thank the Water Research Commission for the funding.
iii
Reference group:
Prof. Heinz Meissner
iv
Table of Contents
Executive Summary ............................................................................................................................................ i
Acknowledgements ............................................................................................................................................iii
1. Introduction .................................................................................................................................................... 1
1.1. Dairy industry overview and growth projections ..................................................................................... 1
1.2 Project objectives ..................................................................................................................................... 3
1.3. Methodology............................................................................................................................................ 4
1.3.1 Sampling of companies ..................................................................................................................... 4
1.3.2 Questionnaire administration ............................................................................................................ 4
1.3.3 Wastewater sample collection and analyses .................................................................................... 4
2. Process overview ........................................................................................................................................... 5
3. Regulations .................................................................................................................................................... 5
3.1 Department of Trade and Industry ........................................................................................................... 5
3.2 The Department of Health ........................................................................................................................ 5
3.3 The Department of Agriculture, Forestries and Fisheries. ....................................................................... 7
4. Water use and management .......................................................................................................................... 7
4.1 Major products ......................................................................................................................................... 7
4.2 Distribution of South African dairy processing plants .............................................................................. 7
4.3 Water sources used by dairy processing plants ...................................................................................... 9
5. Wastewater generation and management ................................................................................................... 10
5.1 Washing effluents form different sizes of companies ............................................................................ 10
6. Energy use and management ...................................................................................................................... 15
7. Water use: best practice .............................................................................................................................. 17
4.4 Level of water use during processing .................................................................................................... 17
8. Wastewater management: best practice...................................................................................................... 17
8.1 Water conservation strategies ............................................................................................................... 17
8.1.1 Cleaner production .......................................................................................................................... 17
8.1.2 Water pinch ..................................................................................................................................... 18
8.1.3 Management ................................................................................................................................... 18
8.1.4 Use of grey water ............................................................................................................................ 19
8.2 Treatment methods of wastewater used in the South African dairy industry ......................................... 20
9. Recommendations ......................................................................................... Error! Bookmark not defined.
10. References ................................................................................................... Error! Bookmark not defined.
v
List of Tables
Table 1: Dairy products in dairy processing plants from different sizes of company ........................................ 8
Table 2: Specific water intakes ........................................................................................................................ 11
Table 3: Effect of size of the company on effluent from washing equipment .................................................. 12
Table 4: Effect of size of the company on dairy products effluents ................................................................. 13
Table 5: Effect of size of the company on effluent from pasteurizer cooling machine .................................... 13
Table 6: Effluent mixture before and after wastewater treatment .................................................................... 14
Table 7: Effect of province on pollutant loads of dairy effluents ...................................................................... 15
Table 8: Effect of different dairy products on pollutant loads of effluents ........................................................ 16
Table 9: Energy cost for consumption by dairy plant for different processing ................................................. 16
Table 10: High water use during processing from different sizes of companies ............................................. 17
Table 11: Association of period of operation with water conservation strategies adopted by companies ...... 21
vi
List of Figures
Figure 1: Total milk production and number of dairy cows (DAFF, 2011) ......................................................... 2
Figure 2: Exports and import of milk and dairy product (in millions) (DAFF, 2011) ........................................... 2
Figure 3: Dairy dry product (DAFF, 2011). The values represent the percent contribution of the total. ............ 3
Figure 4: Flow diagram for the production of cheese ........................................................................................ 6
Figure 5: Percentage of dairy processing plants in different scales of size across the provinces of South
Africa .................................................................................................................................................................. 9
Figure 6: Water source used by companies .................................................................................................... 10
Figure 7: Wastewater treatment method used by different size scale of companies ...................................... 21
vii
1. Introduction
1.1. Dairy industry overview and growth projections
South Africa faces water shortages, with annual fresh water availability less than 1 700 m 3 per capita
(Department of Agriculture, Fisheries and Forestry, 2012). It is estimated that by 2025, the country will have
fresh water availability of less than 1000 m 3 per capita. This scenario is also highly provoked by inadequate
water conservation and recycling occurring in the manufacturing industry. In South Africa, agriculture
receives about 60 %, environmental use 18 %, urban and domestic use 11.5 %, mining and industrial use
10.5 % of water supply (Department of Water Affairs, 2012). The largest portion within agriculture goes to the
dairy industry of which between 75 and 95 % of the water intake is discharged as effluent (DAFF, 2011).
The South African dairy industry has about 250 dairy companies with approximately 1 million cows producing
more than 2.65 million kg of milk (Strydom et al., 1993; Department of Agriculture, Forestry and Fisheries,
2011). Milk processors produce about 1.86 x 109ℓ (Dairy Board, 1990) of effluents. Water use and the
effluent discharged vary with the type of produce and size of the company (NATSUR4, 1989).
Numerous studies reported different pollutant loads parameters. Strydom et al. (1997) reported a chemical
oxygen demand (COD) of 5 340 mg.ℓ-1 from cheese manufacture; 4 656 mg.ℓ-1 from milk and 1 908mg.ℓ-1
from milk powder or butterfat products. NATSURV4 (1989) reported COD for whole milk of 210 000 mg.ℓ -1,
skimmed milk of 100 000 mg.ℓ-1, butter milk of 110 000 mg.ℓ-1and whey of 75 000 mg.ℓ-1. Therefore, pollutant
loads for grey water produced from different products vary with the type of products.
The dairy sector is experiencing increases in water usage, facing challenges in the disposal of effluent and is
in a high need for conserving water (Water Research Commission, 1989). The development of new
technologies and new products being introduced on the market, result in increase of water usage and energy
so is effluent generation. The use of wastewater in livestock rearing is rather rare.
There has been a dramatic change in dairy industry over the past years. The increase in demand for milk
due to increase in population is increasing pressure on milk producers, hence, the price for milk has doubled
between 2001 and 2010 (DAFF, 2011). Milk production has been increasing from 2005 but decline in
2009/10 (Figure 1), while milk exports as well are decreasing (Figure 2). This maybe is due to inflation, land
reform issues, less profit as well and more farmers getting out the industry. The ability of people to know
about the importance of nutrition, school feeding programmes and teenage pregnancy has resulted to
increase milk consumption (DAFF, 2011). The practice of re-using water is still less but surely increasing
with time. Common dairy products which are highly produced and consumed at the moment are cheese,
pasteurized milk, UHT product and milk powder (Figure 3).
1
3000
Production Million litres
2500
Cow (000)
2000
1500
1000
500
0
2000/01 2001/02 2002/03 2003/04 2004/05 2005/06 2006/07 2007/08 2008/09 2009/10
Figure 1: Total milk production and number of dairy cows (DAFF, 2011)
50
45
Exports
40
Imports
35
30
25
20
15
10
5
0
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
Figure 2: Exports and import of milk and dairy product (in millions) (DAFF, 2011)
2
Other cheese, 16
Milk powder, 19
Butter, 11
Hard and semi
cheese, 38
Whey
powder
,8
Buttermilk
powder, 1
Condensed milk, 7
Figure 3: Dairy dry product (DAFF, 2011). The values represent the percent contribution of the total.
Changes in the type of products and size of company over time, in addition to willingness of the
management, are likely to influence the extent to which water is conserved and recycled. Increases in the
size of the operation have the consequence of increasing the cost of electricity and effluent treatment. Due to
changes in technology, different dairy products, processing and scale, pollutant loads for effluent vary. No
information on the extent of water recycling is available. There is a need to quantify the pollutant loads
produced by dairy processing plants to understand and apply corrective measures against disposal or reuse.
The latest report on wastewater generation and conservation in the dairy industry was last performed in 1989
(NATSURV, 1989). There is, therefore, need to update the information so as to produce appropriate
recommendations for use in the industry, by government, researchers and environmentalists. The cost of
electricity and levels of water utilization need to be determined and quantified.
1.2 Project objectives
The objectives of the study were, therefore to:
1. estimate water usage among different sizes of dairy industries across provinces;
2. assess level of awareness of dairy industries in water conservation; and
3. determine pollutant loads of effluents from dairy companies.
3
1.3. Methodology
1.3.1 Sampling of companies
A list of dairy industries was obtained from the Department of Economic Development and the Milk South
Africa website (www.milksa.co.za). Companies were selected throughout the country. The dairy companies
were categorized into three size categories. Companies processing less than 400 kl of milk per day, using
less than 400 kl of water per month and operating at less than R12 900 electricity per month were
considered small. Medium scale companies processed between 400 to 900 kl of milk per day, using less
than 400 - 2000 kl of water per month and operating at R12 900 – 25 800 electricity per month. Lastly, large
scale companies processed more than 900 kl of milk per day, using more than 2000 kl per of water per
month and operating at more than R12 900 electricity per month. Only companies that were willing to
participate in the study were considered.
1.3.2 Questionnaire administration
Structured questionnaires were sent to 233 milk registered processors. Questionnaires were sent out via
emails and fax. Respondents were given four weeks to return the filled questionnaires. The questionnaire
covered the following aspects: volume of milk processed; water and electricity usage; types of dairy product
produced; water source used, effluent treatment methods and water conservation practices adopted. Out of
233 questionnaires sent to participants, only 60 questionnaires were returned back answered. Participants
were given extra four weeks to complete the questionnaires, but none responded. Direct calls were then
made to participants and only 43 companies agreed to participate making a total of 103 companies to be
surveyed.
1.3.3 Wastewater sample collection and analyses
Thirty dairy processing plants agreed to participate in the study hence were chosen for sample collection.
Processing plants were categorized into three sizes namely; small scale (n=30); medium scale (n=30) and
large scale (n=30).The study was conducted on dairy processing plants located in KwaZulu-Natal, Gauteng,
Eastern Cape, Western Cape, Free State and Limpopo provinces.
Grey water was collected with a sterilized 1ℓ plastic bottle and 150 mℓ plastic beaker (for coliform counts) and
stored at 5 ± 1°C. Within each size of the company, six samples were collected for each source of
wastewater (wash equipment’s, products effluents, effluent mixture before treating, effluent mixture after
treating, machine cooling effluent). Effluents were collected during the end stage of each production.
Effluents were classified according to treatments (size of company and production) and control (fresh water).
Grey water was taken to Talbot laboratories in Pietermaritzburg for analysis of pollutant loads.
Parameters measured were chemical oxygen demand (COD), total suspended solids (TSS), nitrates,
chlorides, colour, pH, dissolved calcium, dissolved magnesium, fluoride and sulphate concentrations, total
dissolved solids, total hardness, turbidity (NTU) and total coliforms.
4
2. Process overview
As indicated in NATSURV 4 (1989), dairy processes are as diverse as dairy products. Processes followed in
processing milk have largely remained unchanged. The only major change has been the introduction of new
technology that is faster and efficient in electricity usage. As such, the major steps in the production of
pasteurized milk are raw milk reception, pasteurization, standardization, de-aeration, homogenization,
cooling and packing. Production of whey powder involves evaporation of over 87 % of the water of the milk
before spray drying to remove the remaining water. Dairy cream is the major raw material for butter
manufacture. The cream is largely obtained from other processes carried out on the same dairy site.
Cheese, the most popular dairy product in South Africa (see Figure 3), is produced through milk
standardization, pasteurization, enzyme culture that produces a coagulum. The curd that is produced is
heated and the resultant whey and curd grains are separated. The curd is further drained of whey, moulded,
pressed, coated, wrapped and, finally packed (Figure 4).
3. Regulations
The dairy industry in South Africa is regulated by three government departments. The Department of Trade
and Industry, the Department of Health and the Department of Agriculture, Forestry and Fisheries are all
involved. Each department controls a specific component of the legislation governing the dairy industry
through relevant Acts, Regulations and Guidelines.
3.1 Department of Trade and Industry
The Department of Trade and Industry controls the Consumer Protection Act, Compulsory Specifications and
the Trade and Metrology Act.
3.2 The Department of Health
The Department of Health controls a number of legislation governing milk and other food products. It governs
the Foodstuffs, Cosmetics and Disinfectants Act, 1972 (Act 54 of 1972). It also governs regulations on the
use additives, sweeteners, acids, bases and salts to milk. The Department of Health also regulates the use
of preservatives and antioxidants, food colourants, emulsifiers, stabilisers and thickeners in milk.
Compositional standards of milk are also regulated. Hygiene-related matters are also regulated by the
Department of Health. Regulation R962/2012, for example, regulates the general hygiene requirements for
food premises and the transport of food. Regulation R961/2012 provides regulations relating to milk sheds
and the transport of milk. The Department of Health also regulates foodstuffs for infants and children.
Microbiological standards of milk are also regulated by the Department of Health. The Regulations relating to milk and
dairy products (R1555/1997), Regulations relating to milk and dairy products: Amendment (R866/2008), Regulations
relating to milk and dairy products: Amendment (R127/2014) all regulate the expected standards of milk.
5
Raw milk
Standardisation
milk
Figure 4: Flow diagram for the production
of cheese
Pasteurisation
milk
Rennet
milk
Culture
milk
Curd manufacturing
Drainage
Foaming
Cheddaring
Pressing
Milling
Brining
Salting
Curing
Foaming
Waxing
Pressing
Wrapping
Gouda cheese
Curing
Cheddar cheese
6
3.3 The Department of Agriculture, Forestry and Fisheries
The Department of Agriculture, Forestry and Fisheries controls the Animal Diseases Act, 1984, Act 35 of
1984 and the Agricultural Product Standard Act of 1990. It also regulates the sale of dairy products and
imitation dairy products (R2581/1987).
4. Water use and management
South African currently produces 2763 million litres of milk, of which 973 million is processed into cheese,
1292 million to fresh milk products, and 498 million to milk powder and butter. The amount of water (in
millions of litres) used to process these volumes of milk are 2867, 4008 and 2259 for cheese, fresh milk and
milk powder/butter fat, giving a total of 9.2 million m3 of water. These values indicate for respective
products a specific water usage (litre/litre) of 2.95, 3.10 and 4.53, and are close to values suggested by
Strydom et al. (1997).
4.1 Major products
Pasteurised milk was the leading product produced followed by cheese, yoghurt, sour milk, fruit juice blends,
fruit juice and ice cream (Table 1). More than half of the medium-sized companies (56.8 %) produced
pasteurized milk. Cheese was the mostly produced by small-sized companies (54.4 %). Cultured products
(yoghurt and sour milk) were mostly produced by large companies. Fruit juice blends were mostly produced
by large companies (33.3 %) followed by medium companies (32.4 %). Ice cream seemed to be produced
highly by small companies (60.9 %) compared to large companies (38.9 %).
4.2 Distribution of South African dairy processing plants
The distribution of the dairy companies that participated in the study is shown in Figure 5. Dairy processing
plants were mostly found in Western Cape (38.5 %), Gauteng (25.2 %), KwaZulu-Natal (16.1 %) and Eastern
Cape (10.1 %). Small companies were the most dominated companies across all provinces. Medium-sized
companies were mostly found in Western Cape (37.5 %) followed by Gauteng (27.5 %) and KwaZulu-Natal
(12.9 %). Large companies were mostly found in Western Cape and Gauteng (37.5 %) and KwaZulu-Natal
(18.8 %). Most large (81.3 %) and medium-sized companies (42.5 %) had been in operation for more than
20 years while small companies (42.6 %) have operated for less.
7
Table 1: Dairy products in dairy processing plants from different sizes of company
Size of the company (%)
Product
small (n=47)
medium (n=40)
large (n=16)
Pasteurized milk
45.7
56.8
50
UHT milk
6.5
2.7
11.1
Sterilized milk
2.2
0
11.1
Milk powder
0
5.41
11.1
Processed cheese
8.7
0
0
Cultured butter milk
0
8.1
11.1
Butter
4.4
10.8
11.1
Custard
0
0
11.1
Cheese
54.4
35.1
38.9
Yoghurt
26
37.8
50
Desserts
2.2
0
5.6
Sour milk
8.7
24.3
44.4
Low fat milk
2.2
13.5
5.6
High fat milk
2.2
2.7
11.1
Fruit juice blends
4.4
32.4
33.3
Pasteurized milk
0
13.5
11.1
Sour cream
2.2
8.1
22.2
Fruit Juice
2.2
24.3
16.7
Ice-cream
60.87
27
38.9
8
45
Size scale of the company (%)
40
35
30
25
20
15
10
5
0
Provinces
small (n= 47)
medium (n= 40)
large (n= 16)
Figure 5: Percentage of dairy processing plants in different scales of size across the provinces of South
Africa
4.3 Water sources used by dairy processing plants
The water source used by companies was not associated with the size of the company (Figure 6). Similarly,
location and period of operation were not associated with the water source used by the dairy companies.
9
Size of the company (%)
25
20
15
10
5
0
Municipal tap
water
Rain water
Recycled
River
Borehole
fountain water
Water source
Small
Medium
Large
Figure 6: Water source used by companies
The specific water targets are shown in Table 2. Most large companies are closer to meeting the targets and
are eager to explore and consolidate water conservation strategies. Small companies use high amounts of
water and hardly keep records of their water consumption levels.
5. Wastewater generation and management
5.1 Washing effluents form different sizes of companies
The effect of size of company on colour, dissolved calcium, dissolved magnesium, fluoride concentrations,
pH, TDS, total hardness and total coliforms was highly significant (Table 3). The effect of size on chloride
was also significant. The COD, suspended solids, nitrate/nitrite and turbidity was not affected by the size of
the company.
10
Table 2: Specific water intakes
Product
Mean water use in 1989
Mean water use in 2014
Water use target
1.6
1.4
0.75
Satchets
1.7
1.5
1.1
Cartons
2.2
2.0
1.5
Cultured products
10.2
9.0
6.3
Fruit juices and mixes
2.7
2.5
1.7
Sterilised/UHT products
3.7
3.6
2.0
Skim milk
3.6
3.5
2.1
Ice cream
2.5
2.5
1.9
Products in units of m3/ton:
Milk powder
11.8
11.0
8.7
Cheese
23.0
21.2
20.0
Butter
1.5
1.4
1.3
Condensed milk
4.4
4.0
3.5
Pasteurized
milk
–
bulk
production
Pasteurized milk packed in:
Table 4 shows the effect of size of company on pollutant loads of effluents. There was no effect of size of
company on sulphate concentrations. Large companies had higher chemical oxygen demand (COD),
nitrate/nitrite, chlorides, colour, dissolved calcium, dissolved magnesium, fluoride concentrations, total
hardness and total coliforms. Medium companies had high pH, while small companies had high in total
dissolved solids (TDS) and turbidity.
The effect of size of company on effluents from pasteurizer cooling was significant (Table 5). Small
companies had high levels of chlorides, colour, dissolved calcium, dissolved magnesium, sulphate
concentrations, total dissolved solids and total hardness. The nitrate and fluoride concentrations were high
by large companies. Medium companies produced effluents with high chemical oxygen demand (COD),
suspended solids, pH and total coliform counts.
The effluent mixtures had high pollutant loads before treatment (Table 6). The effect of effluent mixture
before and after waste treatment on pollutant loads except for suspended solids, fluoride and pH. The effect
of treating water before disposal reduced the pollutant loads. Total dissolved solids were three times lower in
treated than non-treated effluent.
11
Table 3: Effect of size of the company on effluent from washing equipment
Size of the company
Parameter
Small
Medium
Large
SE
Chemical oxygen demand (mg O2/l)
3350
5747.2
1286.6
2084.4
Suspended solids at 105ْC (mg/l)
1003.8
10
994
328.4
Nitrates/ Nitrites (mg N/l)
1.02
1.55
2.3
0.56
Chloride (mg Cl/l)
239.7
5
39.2
54.2
Colour (mg Pt-Col/l)
8.3
4.6
1
1.09
Dissolved calcium (mg Cal/l)
58
35
13
5.16
Dissolved magnesium (mg Mg/l)
16.1
14
4.4
0.67
Fluoride (µg F/l)
3630
445
100
407.8
pH at 25ْC
8.4
5.15
6.17
0.62
Sulphate concentration (mg SO4/l)
65.5
9.5
13.05
20.5
Total dissolved solids at 180ْC (mg/l)
3572.1
225
76
578.1
Total hardness (CaCO3)
212.1
70
51
15.6
Turbidity (NTU)
1100.9
388
162.56
440.1
Total coliforms (CFU/100ml)
265666.4
664000
996000
25531.8
For all pollutant, provinces had similar loads (Table 7). Fluoride was, however, significantly affected by
province. Fluoride levels were high in the Eastern Cape and Gauteng, followed by KwaZulu-Natal and
Limpopo. The Free State had the least fluoride concentrations.
The effect of different dairy products on pollutant loads is shown on Table 8. The effect of different dairy
products on effluent pollutant loads was highly significant. Milk, yoghurt and sour milk produced effluents
with high levels of suspended solids, total hardness, chloride and fluoride. Dissolved calcium levels were
high on yoghurt and sour milk. High levels of nitrates were observed in effluents from yoghurt and fruit juice.
Total coliform counts were high from yoghurt, mass, milk and fruit blends. The pH, dissolved magnesium and
turbidity were also high in yoghurt, cheese and milk products.
12
Table 4: Effect of size of the company on dairy products effluents
Size of the company
Parameter
Small
Medium
Large
SE
Chemical oxygen demand (mg O2/l)
16617
3442.6
6092
288.5
Suspended solids at 105ْC (mg/l)
536.1
805.4
1607
1.07
Nitrates/ Nitrites (mg N/l)
0.56
0.35
0.94
0.1
Chloride concentration (mg Cl/l)
97
146.4
291
0.6
Colour (mg Pt-Col/l)
14.5
21.3
42.1
0.3
Dissolved calcium (mg Cal/l)
31.2
46.4
93.6
0.33
Dissolved magnesium (mg Mg/l)
3.36
5.7
10.5
0.32
Fluoride concentration (µg F/l)
1033
1550.5
3102.5
1.7
pH at 25ْC
4.98
5.87
4.37
0.28
Sulphate concentration (mg SO4/l)
23.7
100.7
11.3
35.9
Total dissolved solids at 180ْC (mg/l)
8494.2
1224
2447
1.57
Total hardness (CaCO3)
91.9
135.8
273.9
0.62
Turbidity (NTU)
4282
2681.2
2020.5
438.2
Total coliforms (CFU/100ml)
8067.2
10747.6
24196
1.18
Table 5: Effect of size of the company on effluent from pasteurizer cooling machine
Parameter
Small
Medium
Large
COD (mg O2/l)
20.4
26.8
24.7
0.49
Suspended solids at 105ْC (mg/l)
21.1
45.6
34.1
34.1
Nitrates/ Nitrites (mg N/l)
0.08
0.08
0.86
0.01
Chloride concentration (mg Cl/l)
175.4
13.1
94
0.36
Colour (mg Pt-Col/l)
1.15
2.4
1.5
0.14
Dissolved calcium (mg Cal/l)
83.9
8.32
45.3
0.4
Dissolved magnesium (mg Mg/l)
27.5
1.1
15.1
0.4
Fluoride concentration (µg F/l)
410.7
439.9
424.5
0.8
pH at 25ْC
6.7
7.74
7.26
0.05
Sulphate concentration (mg SO4/l)
133
7.7
71.3
0.6
Total dissolved solids at 180ْC (mg/l)
661.5
61.9
361.4
0.76
Total hardness (CaCO3)
323.8
25
174.7
0.4
Turbidity (NTU)
0.7
5.3
4.3
0.4
Total coliforms (CFU/100ml)
14.2
2412.1
1221.2
6.2
13
SE
Table 6: Effluent mixture before and after wastewater treatment
Effluent mixture
SE
Before treatment
After treatment
Chemical oxygen demand (mg O2/l)
10202.2
1940.5
2630.2
Suspended solids at 105ْC (mg/l)
5822.3
460.7
2607.6
Nitrates/ Nitrites (mg N/l)
5.8
13.4
2.6
Chloride concentration (mg Cl/l)
368.9
113.2
163.7
Colour (mg Pt-Col/l)
206.6
27.9
54.8
Dissolved calcium (mg Cal/l)
133.8
39.9
23
Dissolved magnesium (mg Mg/l)
21.2
9.2
2.8
Fluoride concentration (µg F/l)
2660.7
1669
pH at 25ْC
7.7
7.0
0.5
Sulphate concentration (mg SO4/l)
53.8
7.0
27.1
Total dissolved solids at 180ْC (mg/l)
3925.8
1101.4
566
Total hardness (CaCO3)
418
130.7
67.4
Turbidity (NTU)
2969.5
585
580
Total coliforms (CFU/100ml)
36838.9
1233.6
Parameter
14
450.5
9433.1
Table 7: Effect of province on pollutant loads of dairy effluents
Province
Parameter
KwaZulu-
Limpopo
Free State
Natal
Eastern
Gauteng
Cape
Chemical oxygen demand(mg O2/l)
4165.7
9682
4202
2773.5
4301
Suspended solids at 105ْC (mg/l)
1471.7
1232.7
1225.3
855.5
1282.7
5.1
0.05
9.0
4.7
0.5
Chloride concentration (mg Cl/l)
109.3
9
70.9
242.5
264.7
Colour (mg Pt-Col/l)
40.1
624.7
73.5
35.1
694.7
31
62.3
28.16
36
65
11.9
10
9.7
12.7
13
1236.3
2231
171.4
4256.3
2433
pH at 25ْC
6.8
6.2
8.4
9.1
6.3
Sulphate concentration (mg SO4/l)
46.2
7.3
41.2
72.2
79.4
Total dissolved solids at 180ْC (mg/l)
4223
264
1937.7
2409
1886
Total hardness (CaCO3)
91.9
135.8
273.9
273.9
273.9
Turbidity (NTU)
1881.4
422.5
1794.9
1199.0
1493.7
Total coliforms (CFU/100ml)
257.3
1026.3
60
287.3
8086.3
Nitrates/ Nitrites (mg N/l)
Dissolved calcium (mg Cal/l)
Dissolved magnesium (mg Mg/l)
Fluoride concentration (µg F/l)
The wastewater (in millions) million that is generated from cheese, liquid milk (fresh and cultured) and dry
by-products (milk powder and butter) was estimated to be 852, 77.5 and 436 m 3/ year. The estimate was
generated from the knowledge that milk contains 87.5 % water. The total effluent generated is, therefore, the
sum of 1 365 and 9 135, which gives 10 500 million m3 per year.
6. Energy use and management
In dairy processing, the major energy consumption starts from the refrigerator in the collection area, where
raw milk is kept once being produced on the dairy farm. Energy required for refrigeration of one ton of
product is between 100 and 120 mega joules (MJ) electric energy (Riva, 1992). The energy required for
pasteurization is 90 MJ for plants that are using plastic packaged bottles. The energy required for making
cheese and yoghurt product is the same as for pasteurization across the entire plant (Table 9) and differs
from other milk products (Riva, 1992).
15
Table 8: Effect of different dairy products on pollutant loads of effluents
Product
Source
Cheese
Milk
Yoghurt
Sour
Fruit
milk
juice
SE
blends
Chemical oxygen demand (mg O2/l)
8552.1
4789.5
3035
2171
21.8
512.9
Suspended solids at 105ْC (mg/l)
2034.8
822.1
830.1
830.1
10.3
101.1
0.7
0.27
0.08
1.3
0.03
0.03
Chloride concentration (mg Cl/l)
178.3
91.4
92
92.2
5.2
6.92
Colour (mg Pt-Col/l)
26.2
17.8
22.5
21.8
1.6
1.03
Dissolved calcium (mg Cal/l)
57.3
36.8
43.7
43.7
6.3
2.25
Dissolved magnesium (mg Mg/l)
6.2
4.43
5.6
5.61
2.75
0.27
1895.1
1007.2
1092.6
1092.6
100.8
74.7
pH at 25ْC
3.75
4.37
4.2
5.9
7.58
0.18
Sulphate concentration (mg SO4/l)
13.5
8.18
7.69
4.65
4.58
0.68
Total dissolved solids at 180ْC (mg/l)
4054.6
1228.3
547.1
211.4
63.1
266.28
Total hardness (CaCO3)
167.2
92.3
92.7
92.7
28.4
6.42
Turbidity (NTU)
2442
1073.6
933.8
5512
0.47
115.4
14787.9
8154.5
8347
8333.8
8339.4
569.7
Nitrates/ Nitrites (mg N/l)
Fluoride concentration (µg F/l)
Total coliforms (CFU/100ml)
Table 9: Energy cost for consumption by dairy plant for different processing
Final product
Electricity requirement [MJ/t of milk]
Milk in bottles
Pasteurization
200
Sterilization
250
Skim milk powder and butter
325
Full cream milk powder
290
Cheese
310
Condensed milk
220
The average cost of electricity per month was 9 500 kwh, 17 700 kwh and 25 200 kwh for small,
medium and large dairy industries, respectively. From these estimates, it could be argued that the dairy
processing industry is not an energy intense industry. New technologies being used have contributed to
reducing the electricity cost.
16
7. Water use: best practice
7.1 Level of water use during processing
As expected, the amount of water used for processing was influenced by the size of the company.
Large companies used high volumes of water during receiving, steaming, filling and cooling (Table 10).
The water application at processing during packing, cleaning-in-place, boiling and cold storage was
observed to be the same across all sizes of companies. There was no association between processing
and location. Similarly, period of processing was not associated with levels of water used for
processing. A majority of these companies (84 %) indicated the need for conserving water. The
perception for those companies to save water was not influenced by period of operation and location.
Table 10: High water use during processing from different sizes of companies
Processing
Size of the company (%)
small (n=47)
medium (n=40)
large (n=16)
Receiving
19.6
12.2
68.8
Steaming
17.4
24.4
62.5
Packing
4.4
24.4
6.3
Filling
13.0
4.9
31.3
Cooling
39.1
7.3
93.8
Cleaning-in-place
78.3
53.7
93.8
Boiling
54.4
95.1
75.0
Cold storage
6.3
4.9
6.3
8. Wastewater management: best practice
8.1 Water conservation strategies
Conserving water not only saves money but also reduce pollutant loads. Having high waste water and
pollutant loads indicate that less product is being made while cost is increasing. This may be due to
various reasons, including management. There are many ways of conserving and purifying water within
the industry. This includes cleaner production, water pinch, water foot print management and grey water
use.
8.1.1 Cleaner production
Cleaner production is defined as a technique or practice that eliminates the use of hazardous
substances “through the use of non-hazardous chemical”, minimise waste and maximise profit output
(Thorpe, 2009). Cleaner production is integrated into four principles namely: The preventive principle,
the Public Participation Principle, and the Holistic Principle (Thorpe, 2009). All these principles
emphasised taking action or using certain techniques as early as possible to avoid the impact which the
17
dairy plant can have on nature. Such impact include the use of harmful detergents for cleaning which
result in having high concentrations of elements in waste water which makes it hard to recycle the
water. Therefore, using cheap and less harmful detergents could reduce the problem; hence less water
is used for rinsing. Dairy plants that release waste water with untested chemicals should demonstrate
the knowledge of their discharge and be proactive, rather than requiring regulators to show that the
discharge is harmful (Thorpe, 2009). It is better to prevent damage early in the environment than to try
to control or manage the impact later. This is because less money will be used; more time will be
available to do proper planning to reduce polluting the environment.
8.1.2 Water pinch
Water pinch is a technology which analyses water networks and have the ability to decrease
expenditures which has to do with processes using water differently (Ataei et al., 2010). This technology
focuses on savings financially within the industry. This is achieved by optimising activities work load for
inputs such as electricity and water when they are applied at different locations of the plant and enables
the balancing of their usage within the plant. “Pinch Technology does this by making an inventory of all
producers and consumers of these utilities and then systematically designing an optimal scheme of
utility exchange between these producers and consumers” (Strauss, 2006). As this technology is able to
reduce utilities using water differently, this means that fresh water usage is reduced and so is its cost.
Having an ability to use fresh water less and promote the reuse of water within the industry, result in
less effluent discharge into the environment. This also increases water availability for use in the
communities.
8.1.3 Management
In dairy processing plant, water is the largest consumed input; hence, it is used for different processes
such as heating, cooling, washing, and cleaning up. Many dairy plants use more than 4 gallons of water
to process each gallon of milk (Rausch and Powell, 1997). This can be mainly due to poor management
and or the type of technology the plant uses. Harper et al. (1971) suggested that one of the ways to
reduce water use and effluent generation in dairy processing plant is to apply proper management,
engineering practices and computer modelling to evaluate the impact of proposed changes within the
processing plant. Carawan et al. (1979) concluded that proper management and improved technology
or design could reduce water requirement that is required by the vitaline machine (machine used to
produce new stick type ice cream). This occurred after they observe that vitaline machine used about
28 % water in order to produce frozen product. Workers require proper management as not all staff is
properly skills within the industry (but depends on the dairy processing plant). Therefore, if improper
management is used problems like over washing cases than required, spills, drip, malfunction of
equipment and worker carelessness will result (Carawan et al., 1979). Many plants have successfully
reduced water use to one gallon per gallon of milk used for processing and this has been achieved by
implementing proper management. Therefore, to save water cost, water usage and effluence
18
generation, it is important to consider management first. The extent of water conservation in the dairy
plants in South Africa needs to be determined.
8.1.4 Use of grey water
Physical treatment methods applied to grey water includes soil filtration, coarse sand filtration and
disinfection (boiling). Soil treatment helps to remove organic pollutants and total phosphorus. Due to
natural reactions (nitrification and de-nitrification) which take place also in the soil, nitrogen is reduced
successfully in grey water (Li et al., 2009). The coarse sand treatment has less effect on reduction of
pollutants if applied alone. March et al. (2004) observed a reduction of COD from 171 to 78 mg/ℓ, and
the turbidity from 20 NTU to 16.5 NTU when a nylon sock filter, sedimentation and disinfection steps
were used. Li et al. (2009) observed a little effect of sand filter when it was combined with carbon and
disinfection as 48 % of the suspended solids were removed and turbidity was reduced by 61 %.
However, Pidou (2006) reported an adequate reduction of micro-organisms.
Chemical treatment includes chlorine treatment, coagulation, photo-catalytic oxidation, ion exchange
and granular activated carbon (Li et al., 2009). Chlorine disinfection methods have been widely used to
disinfect both green water and grey water. The mechanism behind the effect of chlorine in inactivating
microorganisms is not yet understood (Winward, 2008). Virto et al. (2005) explained that the cell
membrane of bacteria experiences a change in permeability once chlorine has been introduced. The
membrane determines the extent to which the bacteria are susceptible or resistant to the chlorine effect.
Another widely used method is coagulation. Pidou et al. (2008) reported a reduction in COD from 55-22
mg/ℓ, the BOD 23-9 mg/ℓ, the turbidity 43-4 NTU after electro coagulation was used followed by a
disinfection method. These results were also confirmed by Pidou et al. (2008).
Biological treatments include a variety of methods including rotational biological contactor (RBC)
sequencing batch reactor (SBR), anaerobic sludge blanket (UASB), constructed wetland (CW) and
membrane bioreactors (MBR) (Li et al., 2009). A lot of work has been done on different types of
biological treatments and all concluded with similar result. The most commonly found case is that
biological treatment are followed by filtration steps, mainly sand filtration, then disinfection step follows
so as to meet the standards (Li et al., 2009). Friedler et al. (2005) reported a reduction in TSS 43 mg/ℓ 16 mg/ℓ, Turbidity 33 NTU-1.9 NTU, COD 158 mg/ℓ- 46 mg/ℓ, BOD 59 mg/ℓ- 6.6 mg/ℓ and faecal coliform
5.6×105/100 ml- 9.7×103/100 ml after they combine RBC, sand filtration and chlorination. The result
also accords to the result by Nolde (1999) who used RBC in combination with UV disinfection stage.
Grey water is utilised in many different ways, which includes irrigation, toilet flushing, animal use
(drinking by animals; regulation of temperature in chickens, animal feed), and cement production
(Santala et al., 1998). Irrigation is further classified to irrigation at lawns of college campuses,
cemeteries and golf courses (Okun, 1997). This highly saves water for irrigation required on this site.
Grey water from dairy farms is much high in micro-organisms or manure as they are exposed to cattle
19
dung during washing of the floor. That water can be highly beneficial to crops farming, hence, grey
water contains some quantities of phosphorus and nitrogen which can benefit farmers with no manure
or fertilizer (Eriksson et al., 2002; Morel and Diener, 2006). The application of grey water for irrigation in
gardens as well as small scale agricultural sectors reduce fresh water demand; hence, this can also
contribute to the food security status in rural settlement by the provision of nutritional water suited for
irrigation of crops (Murphy, 2006, Rodda et al., 2011). A saving on water decreases the cost of buying
water. This also reduces waste water contamination to rivers and lakes which could reduce salinity,
pollution and eutrophication. Grey water used for toilet flushing can reduce up to 30 % water demand
(Karpiscak et al., 1990). This reduces fresh water usage but increase work load on sewage treatment
such that if heavy or poisonous substances are exposed, difficulty to retreat water may result.
In animal use, grey water is mostly used in production for broilers (Santala et al., 1998). In cheese
production, whey can be used in broiler production (NATSURV 4, 1989). Whey is high in protein and
biological value (BV), it is a supplement rich in proteins. Therefore, liquid whey and associate effluents
become a saving on water within the dairy plant and a benefit for broiler feed production as a grey water
component. Also the regulation of temperature on poultry using grey water is a huge saving for grey
water re-use. The water can also be used for drinking by livestock, such as pigs. It is crucial for grey
water not to depress animal productivity. The acceptable levels of water quality for pigs are pH6.5-8.5,
TDS ≤ 1000 ppm and hardness ≤ 60 ppm (NRC 1998; Nyachoti and Kiarie, 2010). The issue of water
analysis, therefore, plays an important role to assess the quality for grey water so that proper treatment
can be applied.
As shown in Table 11, the period of operation for water conservation strategy was associated with the
processing. Irrigation strategy was the most adopted strategy used followed by recycling, water pinch
and grey water (for cleaning). There was no association observed on size and location in comparison
with water conservation strategy.
8.2 Treatment methods of wastewater used in the South African dairy industry
There were 61 % companies that did not treat water before disposal. There was no association between
water treatment method and size of the company (Figure 7). The location and period of operation of the
company was also not associated with willingness to save water.
20
Table 11: Association of period of operation with water conservation strategies adopted by companies
Period of operation (%)
Conservation strategy
<10 years
10 - 20 years
Cleaner production
>20 years
1.9
1
1
0
1.9
1
Water pinch
1.9
4.9
0
Grey water
3.9
1
1
1
0
0
Irrigation
6.8
17
8.7
Recycling
10.7
7.8
4.9
Livestock drinking
Life cycle management
30
Size scale of company (%)
25
Small
Medium
Large
20
15
10
5
0
none
Biological
Chemical
Water treatement method
Figure 7: Wastewater treatment method used by different size scale of companies
21
Physical
9. Recommendations

No facility should be allowed to discharge untreated effluent to the municipal sewage system.

All facilities should be monitored for effluent compliance as often as possible by the
authorities.

The efficacy of recycling of treated effluent should be prioritized and re-investigated.

The trends in the demand for dairy products need to be accurately estimated to facilitate
prediction of water needs for the dairy industry.

Possibilities to separate effluent from cleaning, whey and black water should be considered and
investigated.

No facility should be allowed to discharge untreated effluent to the municipal sewage system.

All facilities should be monitored for effluent compliance as often as possible by the
authorities.

The efficacy of recycling of treated effluent should be prioritized and re-investigated.

The trends in the demand for dairy products need to be accurately estimated to facilitate
prediction of water needs for the dairy industry.

Possibilities to separate effluent from cleaning, whey and black water should be considered and
investigated.

Use of water meters in measuring water coming in and effluent coming out is essential.

Data on the type of equipment used, processes involved for specific products, water use and
pollutant loads is essential.

Studying the effect of different source of dairy effluent on performance and behaviour of
livestock, particularly pigs that consume large quantities of water.

Effect of location (within a province) on water utilization, conservation and effluent pollutant
loads should be evaluated.

Methods and time of storage of dairy effluent on pollutant loads for use in livestock feeding
need to be explored.

Processors should consider the use of solar and wind systems to reduce electricity costs.
22
10. References
Ataei, A. & Yoo, C. K., 2010. Simultaneous Energy and Water Optimization in Multiple-Contaminant
Systems with Flow rate Changes Consideration. Int. Journal. Environ. Res., 4 (1): 11-26.
Carawan, R. E., Jones, V. A. & Hansen, A. P., 1979. Wastewater Characterization in a Multiproduct
Dairy. J. Dairy Sci 65(8): 1243-1251.
Department of Agriculture, Forestry and Fisheries, 2011. A profile of the South African Dairy market
value chain. Republic of South Africa.
Department of Water Affairs and Forestry, 2012. Overview of the South African Water Sector.
Available at:
http://www.dwaf.gov.za/IO/Docs/CMA/CMA%20GB%20Training%20Manuals/gbtrainingmanu
alchapter1.pdf. Date Accessed.|2013/07/09|
Friedler, E., Kovalio, R. & Galil, N. I., 2005. On-site grey water treatment and reuse in multi-storey
buildings. Water Sci Technol, 51(10): 187–94.
Karpiscak, M. M., Foster, K. E. & Schmidt, N., 1990. Residential water conservation. Water Research,
26, 939–948.
Li, F.,Wichmann, K. & Otterpohl, R., 2009. Review of the technological approaches for grey water
treatment and reuses. Science of The Total Environment, 407, 3439-3449.
March, J. G., Gual, M. & Orozco, F., 2004. Experiences on grey water re-use for toilet flushing in a hotel
(Mallorca Island, Spain). Desalination 164 (3): 241–7.
Morel, A. & Diener, S., 2006. Greywater Management in Low and Middle-Income Countries, Review of
Different Treatment Systems for Households or Neighbourhoods. Swiss Federal Institute of
Aquatic Science and Technology (EAWAG), Dübendorf, Switzerland. 107 pp.
Murphy, K. O. ’H., 2006. A Scoping Study to Evaluate the Fitness- For-Use of Greywater in Urban and
Peri-Urban Agriculture. WRC Report No. 1479/1/06. Water Research Commission, Pretoria,
South Africa. 143 pp.
NATSURV4., 1989. Water and Waste-Water Management in the Dairy Industry. National Industrial
Water and Waste-water Survey. Pretoria, RSA.
National Research Council. 1998. Nutrient Requirements of Swine (10th ed.). National Academy Press,
Washington, DC.
Nolde, E., 1999. Grey water reuse systems for toilet flushing in multi-storey buildings — over ten years’
experience in Berlin. Urban Water, 1, 275–84.
Nyachoti, C. M. & Kiarie, E., 2010. Water in swine production: a review of its significance and
conservation strategies. Manitoba Swine Seminar, 24, 217-232.
Okun, D. A., 1997. Distributing reclaimed water through dual systems. American Water Works
Association Journal, 89(11), 153–160.
Pidou, M., Avery, L., Stephenson, T., Jeffrey, P., Parsons, S. A., Liu, S., Memon, F. A., Bruce Jefferson,
B., 2008. Chemical solutions for grey water recycling. Chemosphere, 71(1):147–55.
Rausch, K, D. & Powell, G, M., 1997. Dairy Processing Methods to Reduce Water Use and Liquid
Waste Load. Kansas State University, Manhattan, USA.
23
Rodda, N., Carden, K., Armitage, N. & du Plessis, H. M., 2011. Development of guidance for
sustainable irrigation use of grey water in gardens and small-scale agriculture in South Africa.
Water SA, 37 (5): 727-738.
Santala, E., Uotila, J., Zaitsev, G., Alasiurua, R., Tikka, R. & Tnegvall, J., 1998. Microbiological
greywater treatment and recycling in an apartment building. IN: AWT98 – Advanced
Wastewater Treatment, Recycling and Reuse: Milan, 319–324.
Strauss, K, J., 2006. Application of Pinch Technology in water resource management to reduce water
use and wastewater generation for an area. WRC Report No. 1241/1/06.
Strydom, J. P., Britz, T. J. & Mostert, J. F., 1997. Two- phase anaerobic digestion of three different dairy
effluents using a hybrid bioreactor. Water SA, 23(2): 151- 156.
Thorpe, B., 2009. Clean Production Strategies: What is Clean Production? Green peace International.
Virto, R., Manas, P., A´ lvarez, I., Condon, S., Raso, J., 2005. Membrane damage and microbial
inactivation by chlorine in the absence and presence of a chlorine-demanding substrate. Appl.
Environ. Microbiol. 71 (9): 5022–5028.
Winward, G. P., Avery, L. M., Stephenson, T. & Jefferson, B., 2008. Chlorine disinfection of grey water
for reuse: Effect of organics and particles. Water Research 42, 483- 491.
24