Wastewater from agricultural and food processing has distinct characteristics that differentiate it from common municipal wastewater managed by public or private wastewater treatment plants around the world: it is biodegradable and non-toxic, but has high biological oxygen demand (BOD) and suspended Solid (SS). The composition of food and agricultural wastewater is often difficult to predict due to differences in BOD and pH in wastewater from vegetable, fruit and meat products, as well as food processing practices and seasonality.

Processing food from raw materials requires large amounts of high-quality water. Washing vegetables produces water with a lot of particulate matter and some dissolved organics. It may also contain surfactants and pesticides.

Aquaculture facilities (fish farms) often emit large amounts of nitrogen and phosphorus, as well as suspended solids. Some facilities use drugs and pesticides that may be present in wastewater.

Dairy processing plants generate conventional pollutants (BOD, SS).

Animal slaughtering and processing produces organic waste from bodily fluids such as blood and intestinal contents. Produced pollutants include BOD, SS, coliforms, oils, organic nitrogen and ammonia.

The processing of food for sale produces waste from cooking, which is often rich in plant organic material and may also contain salts, flavourings, colouring materials and acids or bases. There may also be large amounts of fats, oils, and greases ("FOGs") that, in sufficient concentrations, can clog drains. Some cities require restaurants and food processors to use grease interceptors and regulate the handling of FOG in sewer systems.

Food processing activities such as factory cleaning, material handling, bottling and product washing generate wastewater. Many food processing facilities require on-site treatment before operating wastewater can be used on land or discharged into waterways or sewer systems. High suspended solids levels of organic particles can increase BOD and can result in high sewer surcharges. Settling, wedge screen or rotating belt filtration (micro-sieving) are common methods to reduce the suspended organic solids load prior to discharge. Cationic high-efficiency oil-water separator are also often used in the treatment of oily sewage in food factories (high-efficiency oil-water separators are used alone or in combination with inorganic coagulants for sewage or wastewater containing anionic chemicals or negatively charged fine particles. All can achieve the purpose of rapid and effective separation or purification of water. The high-efficiency oil-water separator has a synergistic effect, which can speed up the flocculation speed and reduce the cost of using the product).