Page 61 - Materials Chemistry, Second Edition

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Sustainable Industrial Design and Waste Management
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8,250 tons of raw milk to produce 3,100 tons of white and hard cheese and
200 tons of ghee. The farm that uses this byproduct (cheese whey) and in
which the model experiment is to be conducted is the Animal Wealth
Society Farm located 10 km away from the factory. The farm has 725 head of
Holstein, Brown Swiss and Friesian breeds managed under a sophisticated
dairy feedlot operation and quality control.

Waste analysis
The waste generated from this factory mainly consists of:

• Product losses
• Wash water
• Whey

Whey is a liquid byproduct originating from cheese manufacturing, which
has tremendous biological impact. To produce hard cheese more than 83%
of the milk is converted to sweet whey, and to produce white cheese more
than 60% of the milk is converted to permeate whey. This first operation
of sweet whey produced from Grade-A milk takes place from December
to May, and the second process of ultra-filtration occurs through the year.
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Byproducts of these operations are sweet whey (4,250 m /y), deproteinized
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whey (4,070 m /y) and permeate whey (1,900 m /y).
Whey is a variable source of carbohydrates, a good supply of energy, and
contains high quality protein and minerals. Only 4% of the whey is recov-
ered as fat and protein by centrifugation and settling. The remaining whey –
based on its nutritional true value, compared to other protein and energy
sources for remnants such as roughage and mix feed – permeate whey was
determined to be $12/ton. However, these volumes of different types of whey
get mixed with other effluents to be discharged in the city sewer.
The annual factory effluent containing both sweet and permeate whey
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is 183,000 m with BOD (2,300 ppm), COD (4,050 ppm), TSS (540 ppm), TDS
(2,290 ppm) and oil/grease (420 ppm). This highly biologically polluted water
is discharged into the city sewer without prior treatment.
Therefore, to comply with environmental regulations the factory has
to install an industrial wastewater treatment plant. This would involve a
capital cost of at least $17,545 plus the running cost and would involve primary
settling, tricking filters, coagulation, chlorination, and sludge digestion.
From the above analysis the problem is obvious. The factory has to pay
a capital cost of $17,545 in the form of a wastewater treatment station plus the
annual running cost in order to discharge whey that has a nutritional value
of $74,000 per year. To illustrate the problem in the simple language of math-
ematics, the factory has to pay more than $17,545 in order to get rid of $74,000.
Therefore, one of the eight clean production techniques explained above is