The content of the food industry is extremely complex, the wastewater contains organic matter, has a strong oxygen consumption, and a large amount of suspended matter is discharged with the wastewater. Wastewater discharged from animal food processing also contains animal waste, blood, fur, oil, etc., and may contain germs, so the oxygen consumption is high, and the pollution of wastewater discharged from plant food processing is much higher. The difference with other industrial sewage is that the food industry sewage generally does not contain heavy metals, pesticides and other harmful substances, but its BOD, COD, etc. are generally high. Since most of the raw materials used in the food industry are organic substances that can be digested by the human body, the biodegradability of food industry sewage is generally good.

The food industry includes meat processing, aquatic product processing, dairy processing, canning production, brewing, sugar making and many other industries. Therefore, the food industry has a wide range of raw materials and a wide variety of products. The amount of water discharged from sewage and water quality vary greatly. The state implements a food hygiene and safety permit system (QS certification) for many food and beverage industries, stipulating that the process water and finished water used must be purified water.