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. 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