Dairy Waste n Management

1

DAIRY INDUSTRY AND WASTE MANAGMENT 

INTRODUCTION Milk-producing animals have been domesticated for thousands of years. Initially they were part of the subsistence farming that nomads engaged in. As the community moved about the country so did their animals accompany them. Protecting and feeding the animals were a big part of the symbiotic relationship between the animal and the herder herder.. In the more recent past, people in agricultural societies owned dairy animals that they milked for domestic or local (village) consumption, a typical example of a cottage industry. industry . The animals might serve multiple purposes (for example, as a draught animal for pulling a plough as a youngster and at the end of its useful life as meat). meat ). In this case the animals were normally milked by hand and the herd size was quite small so that all of the animals could be milked in less than an hour—about 10 per milker. With industrialisation and urbanisation the supply of milk became a commercial industry with specialised breeds of cow being developed for dairy, as distinct from beef or beef  or draught animals. Initially more people were employed as milkers but it soon turned to mechanisation with machines designed to do the milking. Historically, the milking and the processing took place close together in space and time: on a dairy farm. farm.

SOME DAIRY PRODUCTS

2 Skim milk 

The product left after the cream is removed is called skim, or skimmed, milk. Reacting skim milk with rennet or with an acid makes casein curds from the milk solids in skim milk, with whey as a residual. To make a consumable liquid a portion of cream is returned to the skim milk to make low fat milk  fat milk (semi-skimmed) (semi-skimmed) for human consumption. By varying the amount of cream returned, producers can make a variety of low-fat milks to suit their local market. Other products, such as calcium calcium,, vitamin D, D, and flavouring, are also added to appeal to consumers. Casein

Casein is the predominant phosphoprotein predominant phosphoprotein found in fresh milk. It has a very wide range of  uses from being a filler for human foods, such as in ice cream, cream, to the manufacture of   products such as fabric fabric,, adhesives adhesives,, and plastics and plastics.. Cheese

Cheese is another product made from milk. Whole milk is reacted to form curds that can  be compressed, processed and stored to form cheese. In countries where milk is legally allowed to be processed without pasteurisation without pasteurisation a wide range of cheeses can be made using the bacteria naturally in the milk. In most other countries, the range of cheeses is smaller and the use of artificial cheese curing is greater. Whey is also the byproduct of  this process. Whey

In earlier times whey was considered to be a waste product and it was, mostly, fed to pigs as a convenient means of disposal. Beginning about 1950, and mostly since about 1980, lactose and many other products, mainly food additives, are made from both casein and cheese whey. Yogurt

Yoghurt (or yogurt) making is a process similar to cheese making, only the process is arrested before the curd becomes very hard.

3

WASTE MANAGEMENT IN DAIRY INDUSTRY •

TYPES OF WASTE PRODUCED IN DAIRY INDUSTRY

1) Solid waste 2) Wastewater  3) Air pollution 1. Solid waste

4 Hardly any solid waste is produced by the dairy industry. The main solid waste produced by the dairy industry is the sludge resulting from wastewater  purification. There are figures available about the amount of sludge production: in aerobic systems the sludge production is about 0.5 kg per kg of removed COD and in anaerobic systems about 0.1 kg per kg of removed COD. 2. Wastewater

Wastewater from dairy industry may originate from the following sources: Milk receiving  Wastewater results from tank, truck and storage tank washing, pipe line washing and sanitizing. It contains milk solids, detergents, sanitizers and milk wastes. Whole milk products Wastewater is mainly produced during cleaning operations. Especially when different types of product are produced in a specific production unit, clean-up operations between product changes are necessary. In developing countries, the main problem is pollution through spoilage of milk. Cheese/Whey/Curd  Waste results mainly from the production of whey, wash water, curd particles etc. Cottage cheese curd for example is more fragile than rennet curd which is used for other types of cheese. Thus the whey and wash water from cottage cheese may contain appreciably more fine curd particles than that from other cheeses. The amount of fine particles in the wash water increases if mechanical washing processes are used. Butter/Ghee Butter washing steps produce wash water containing buttermilk. Skim milk and buttermilk can be used to produce skimmilk powder in the factory itself or itself or these materials may be shipped to another dairy food plant by tank truck. The continuous butter production process materially reduces the potential waste load by eliminating the buttermilk production and the washing steps (Harper  et. ., 1971). al ., Milk powder 

5 Environmental problems are caused by high energy consumption (= emission of  CO2, CO etc.), by cleaning and by emission of fine dust during the drying process. Condensed milk/Cream/Khoa Environmental problems related to the production of condensate and khoa are mainly caused by the high energy consumption during the evaporation process. The main suspended solids mentioned in the literature are coagulated milk and fine particles of cheese curd. Table 18 gives an overview of the waste production data for the dairy industry. Reference Waste water prod. BOD

(1)

(2)

Average

Range

Average

Range

2400

100 - 12400

2400

100 - 7100

6

0.2 - 71.2

5.5

0.2 - 7.1

(2.0)

(0.06 - 10.8)

(0.15)

(0.002 - 0.43)

SS Nitrogen Phosphorus

(0.012) (0.007 - 0.16)

. Type of product

Wastewater volume

BOD

Average

Range

Average

Range

Milk

3250

100 - 5400

4.2

0.20 - 7.8

Condensed milk

2100

1000 - 3000

7.6

0.20 - 13.3

(1)

Butter

800

0.85

Milkpowder

3700

1500 - 5900

2.2

0.02 - 4.6

Cottage cheese

6000

800 - 12400

34.0

1.30 - 71.2

(2) Milk (canned)

320 - 1870

0.02 - 1.13

Condensed milk

800 - 7290

0.17 - 1.48

Butter

800 - 6550

0.19 - 1.91

Natural cheese

200 - 5850

0.30 - 4.04

Cottage cheese

830 - 12540

1.30 - 42

(3)

6 Milk

0.2 - 4.0

Cheese

0.9

Butter/milkpowder

0.3

Total

4000

The ranges in Table 19 also indicate that the production of wastewater is highly influenced by management practices (see next paragraph). It is not possible to identify particular waste producing practices. The way in which the water  consuming and operation processes are carried out is indicative of the management quality. The major contribution to he waste load comes from cleaning operations, which take place throughout the production process. Only in the production process of (hard) cheese, is whey sewering one of the main contributors to the waste load.

Waste generating processes of major significance include: - Washing, cleaning and sanitizing of pipelines (metals), pumps, processing equipment, tanks, tank, trucks and filling machines (high N load); - Start-up, product change over and shut down of HTST and UHT pasteurizers; - Breaking down of equipment and breaking of packages resulting in spilling during filling operations; - Lubrication of casers, stackers and conveyors

3. Air pollution In dairy plants air pollution is mainly caused because of the need for energy. In the process gasses may be discharged such as CO 2, CO, NOx and SO2. Table 20 gives the emissions into the air as a result of gas- and oil-combustion. No figures are available about the emissions into the air resulting from the use of  electricity. Emissions of CFC’s and NH 3 into the air may come about as a result of leakage and stripping of chilling machines when out of use. Process:

Air emission (kg/ton processed milk)

Heating by burning gas or oil CO:

0.03

7 CO2:

92

Nox:

0.1

SO2:

0.05

Producing milkpowder

Fine dust:

0.39

Cleaning

VOC:

0.05

MANAGMENT OF WASETE PRODUCTS The waste load, expressed as BOD depends to a large degree on the style of  management. Table 21 gives an example of the relationship between management practices and waste production in terms of BOD and the amount of  wastewater produced. The table shows that a large quantity of processed milk does not necessarily lead to higher waste loads or to higher levels of wastewater  production. Management practices cover a wide range of water consumption and process operation activities. Well controlled processes reflect good management qualifications, while bad practices are a reflection of poor management. Table 21 shows the relationships. The qualification “fair” signifies that good as well as bad practises occur. With good management practices, values of BOD 1 kg/ton and produced wastewater below 1 kg/kg may be reached. Poor management will result in values greater than 3 kg/ton resp. 3 kg/kg. For the evaluation of management practices, the following indicators are useful: 1. Housekeeping practices; 2. Water control practices; frequency with which hoses and other sources of  water are left running when not in actual use; 3. Degree of supervision of operations contributing to either the volume of  wastewater or to BOD coefficients; 4. Extent of spillage, pipe-line leaks, valve leaks and pump seals; 5. Extent of carton breakage and product damage in casing, stacking and cooler  operations; 6. Practices followed during the handling of whey; 7. Practices followed in handling spilled curd particles during cottage cheese transfer and/or filling operations

8 8. The following of practices that reduce the amount of wash water from cottage cheese or butter operations; 9. Extent to which the plant uses procedures to segregate and recover milk solids in the form of rinses and/or products from pasteurization start-up and product change-over; 10. The procedures used to handle returned products; 11. Management attitude towards waste control. Product

Milk processed

BOD

Wastewater

(kg/day)

(kg/ton)

(kg/kg)

181,600

0.3

0.4

excellent: 19, 25, 26

227,000

0.2

0.1

excellent: 19, 21, 26, 27

113,500

0.7

1.0

good: 8, 10, 18, 20

68,100

7.8

5.2

poor: 1

272,400

2.0

0.8

good: 8, 15, 16

135,200

1.3

4.7

good: 8, 17

295100

71

12.4

poor: 2

454,000

4.1

1.2

good: 2, 19

211,110

1.8

1.1

good: 21, 22

408,600

3.3

1.1

fair: 8, 9

454,000

8.6

2.0

poor: 8, 3, 4

Milk, butter

135,200

0.9

0.8

good: 23, 24, 28

Whey powder

227,000

0.2

5.9

good-fair: 11, 12, 13

Milk powder, butter

90,800

3.0

2.5

fair: 14, 7, 3

Milk

Cottage cheese

Milk, cottage cheese

Management level

Source: EPA, 1971

SOME TABLES PROVIDED BY CENTRAL POLLUTION CONTROL BOARD Table 1 : Number and Locations of Agro-based industries S. No.

Industry Segment

Total No. of  Units

Annual Processing/ Production Capacity

Locations

9 1.

Dairy

2.

Edible O i ls Vanaspati

3.

Fermentation

4.

Food & Processing

5.

Pulp & Paper

& 

96

5.5 x 10.66Uttar Pradesh, Kilolitre Maharashtra, Gujarat, Tamil Nadu, Rajasthan

7 25

4.5 x 106 tonne Maharashtra, Andhra Prades Pradesdh, dh, Gujara Gujarat, t, Madhya Madhya Pradesh, Uttar Pradesh 6 2 X 10 Kiloli Kilolitre tre Uttar Uttar Prades Pradesh, h, Mahara Maharasht shtra, ra, Andh Andhra ra Prad Prades esdh dh,, Ma Madh dhya ya Prad Prades esh, h, Karn Karnat atak aka, a, Tami Tamill Nadu

225

Fruit

2 04

89

-

1 x 106 tonne

Maharashtra, Ta Tamil Na Nadu, Andhra Pradesdh, Karnataka, West Bengal

andrapradesh

Table 2: Water Consumption, Wastewater.Ge Wa stewater.Generation neration and Organic O rganic Pollution Load in Agro-based Industrie S. No.

Industry

Specific Water Waste Water Pollution load Consumption generation, (in terms of Kg of  (Cubic Cubic Metre BOD) meters)

1. Dairy (Integrated) (per kilo litre of  milk)

8.7

6.0

11.0

2.

Edib Edible le Oils Oils & Va Vana nasp spati ati (per tonne oil)

3.0

2.0

7.5

3.

Fermentation (i) Brewery (per Kilo Kilo lit litre of beer) eer) (ii) Distillery (per (per kilo kilo litre litre of alcoha alcohal) l) (iii) M al t r y (per tonne of grain)

11.5

9.5

24.0

130.0

90.0

600.0

8.5

3.5

2.0

SUGGESTION FOR DAIRY WASTE CONTROL BY EPA 1. Instruction of plant personnel concerning the proper operation and handling of  dairy processing equipment. Major losses are due to poorly maintained equipment and to negligence by inadequately trained and insufficiently supervised personnel.

10 2. The carrying out of a study of the plant and the development of a material balance to determine where losses occur. Modification and replacement of illfunctioning equipment. Where improper maintenance is the cause of losses, a specific maintenance programme should be set up. 3. The use of adequate equipment for receiving, cooling, storing and processing of milk, so as to take care of the maximum volume of flush production and of  special products. All piping, around storage tanks and other areas, should be checked on mis-assembly and damage that may lead to leakage. 4. Accurate temperature control on plate, tubular and surface coolers to prevent freeze-on, which may result in loss of products. 5. Elimination of valves on the outlet sides of internal tubular or plate heaters and coolers and maintenance of plates and gaskets in good repair so as to eliminate waste due to blown or broken gaskets 6. Installation of suitable liquid level controls with automatic pump stops, alarms, and other devices at all points where overflows could occur (storage tanks, processing tanks, filler bowls etc). 7. Keeping in good order of vats, tanks and pipelines so as to eliminate and reduce to a minimum the number of leaky joints, gaskets, packing glands and rotary seals. 8. Proper design and installation of vats and tanks at a level high enough above the floor for easy drainage and rinsing if hand cleaned. Tanks should be pitched to insure draining. 9. Correct connections on plate type heat exchangers so as to avoid milk being pumped into the water side of the exchanger or water being pumped into the milk side. 10. Provision and use of proper drip shields on surface coolers and fillers so as to avoid that products reach the floor. Avoidance of cheese vats, vat processors or cooling tanks being overfilled so that no spillage occurs during product agitation. The liquid level in cheese vats should be at least three inches below the top-edge of the vat. 11. Avoidance of foaming of fluid dairy products, since foam readily runs over  processing vats and other supply bowls and contains large amounts of solids and BOD. The use of air tight separators, proper seals on pumps and proper line connections to prevent inflow of air when lines are under partial vacuum, will avoid foam production.

11 12. Turning off of water hoses when not in use. Use should be made of hoses equipped with automatic shut-off valves so as to avoid excessive water usage.

REFERENCES 1)CPCB URL 2)EPA URL 3)WIKIPEDIA URL 4)ANSWERS URL