The main raw materials and resources for dairy production in dairy factories are fresh milk, sugar, peanuts, walnuts, electricity, water, and coal. During the dairy production process, wastewater such as tank washing water and bottle washing water is generated. This wastewater, along with floor washing water, toilet flushing water, and a small amount of domestic sewage, enters the factory’s open drainage channel and is discharged outside the workshop through a common outlet. The wastewater mainly contains a large amount of soluble organic matter (sugars, fatty acids, proteins, starch, etc.), has good biodegradability, does not contain toxic or harmful substances, is milky white, and has a COD concentration of approximately 800-1000 mg/L, classifying it as low to medium concentration organic wastewater.
The characteristics of dairy wastewater include:
1. Large fluctuations in water quality and quantity: The discharge volume and concentration of wastewater fluctuate with the cleaning projects and time, with larger discharge volumes and concentrations in the morning and evening. Simultaneously, the wastewater exhibits an unbalanced pH level.
2. High organic matter content: Milk proteins, milk fats, lactoses, etc., exist in the wastewater in one or more forms—dissolved, emulsified, and suspended—resulting in a high COD. 3. Good biodegradability: The dissolved organic matter in dairy wastewater is easily decomposed by microorganisms, and most dairy wastewater can achieve a BOD/COD ratio of >0.5, which shows good biodegradability.
