Cheese whey is produced in the cutting and cooking of curd. Cheese whey, which is a protein and lactose rich byproduct of the cheese industry, is very biodegradable (>99%) with very high organic content (up to a COD of 70 kg m 3) and low alkalinity content (2.5 kgm 3 as CaCO3)
There are generally three types of whey:
- sweet whey, which is generated when enzymes, principally rennet, are used to coagulate the milk. Sweet whey typically contains 0.6–0.9% soluble protein, up to 0.3% fat and large quantities of lactose (up to 5%). The pH value of sweet whey from cheddar cheese manufacturing is generally 5.1-5.3;
- acid whey, which is generated when acid is used to coagulate the milk, for example in the production of cottage cheese. Acid whey typically contains the same proportion of soluble proteins as sweet whey, but less fat and somewhat less lactose (4.5%), since some of the lactose is converted to lactic acid. It has a low pH value, between 4.5 and 4.7;
- salt whey, which is the product expressed during the pressing of salted cheese curd, such as in the manufacturing of cheddar cheese. This whey should be collected separately from other types of whey.
Cheese whey the whey is normally fed to pigs or cows. This is a low-cost solution but the price obtained for whey, after transport costs are considered, is often only a very small fraction of the cost of the original milk.
Due to high organic content and biodegradability of cheese whey, anaerobic digestion is one the most appropriate treatment method for whey and it can be applied to existing facilities.
UNEP.- Cleaner Production Assessment in Dairy Processing