The treatment and disposal of waste waters from dairies and milk products factories.
- Great Britain. Water Pollution Research Board
- Date:
- 1941
Licence: Public Domain Mark
Credit: The treatment and disposal of waste waters from dairies and milk products factories. Source: Wellcome Collection.
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![I] CHAPTER III. METHODS OF REDUCING THE QUANTITY OF MILK AND OF MILK PRODUCTS AND BY-PRODUCTS CARRIED AWAY IN WASTE WATERS | N attempting to solve any problem of treatment and disposal of industrial effluents, the first step should always be to consider the practicability, taking costs into account, of,modifying the manufacturing processes so as to reduce the quantity or the polluting character of the waste waters discharged. Only when all practicable measures have been taken to reduce the quantity of polluting matter leaving the factory should methods of purification of the effluents be considered. Frequently polluting industrial effluents contain valuable raw material, saleable products, or material from which valuable by-products can be recovered. ) In attempting to reduce the quantity of polluting matter in waste waters from the milk industry, the first essential is that in no circumstances should whole whey and buttermilk be discharged with the waste waters. These by-products have in the past been regarded as waste materials at some factories and have been discharged into streams, where they have caused serious pollu- tion. Whey, for example, has a biochemical oxygen demand of over 4,000 parts per 100,000 and is at least 100 times as strong in polluting character as an equal volume of crude domestic sewage. Thus, if the whole of the whey from a cheese factory handling 10,000 gallons of milk per day were discharged into a stream, its polluting effect would be about the same as that of the crude domestic sewage from a town with a population of 40,000 to 50,000 people. Whey and buttermilk should be treated as valuable by-products and not as waste materials. They have high food values and can be utilized as food or in the preparation of foods. There is a market for dried whey and butter- milk and there are indications that the market can be further developed. In the early stages of this investigation it was concluded that the quantities of polluting matter carried away in the waste waters from the various branches of the milk industry could be considerably reduced by simple and relatively inexpensive modifications at the depots and factories to reduce losses of milk and of milk products and by-products. At most milk distributing depots a considerable proportion of the total loss of milk is due to inadequate drainage of churns after they have been emptied into the collecting trough. In some experiments, full 10-gallon churns were emptied and allowed to drain for different periods, after which the milk which could be removed by further drainage was collected and measured. The results in Table VIII were obtained. TABLE VIII. Volume of Milk Remaining in 10-Gallon Churns, after Drainage for Different Periods, and Capable of Removal by Further Drainage Volume of milk re- Period of drainage moved by further (sec.) drainage (ml.) 3 69 10 40 20 30 30 25 60 15 90 8 . In some further experiments, full 10-gallon churns were emptied and were drained for different periods. Each churn was then washed out with 5 litres of water and the weight of oxygen consumed from boiling acid potassium](https://iiif.wellcomecollection.org/image/b32179613_0021.jp2/full/800%2C/0/default.jpg)
