Sewage needs to be discharged when processing casings. High concentration sewage refers to the sewage discharged by adsorbing heparin sodium during the production of casing. It is mainly composed of water, crude protein, fat, water-soluble organic matter and inorganic matter in sewage, of which water accounts for about 97% and others account for about 3%. These two items are the main problems in treating this kind of sewage, and biochemical treatment methods are commonly used.

The production of casing will bring a lot of wastewater, so the sewage generated in the production and processing of casing should be treated in time, and the discharged water pollutants will cause damage to the surrounding environment. Therefore, sewage needs to be discharged when processing casings.

Definition and application of casing

A tough translucent film made by scraping the large intestine and small intestine of livestock. According to the classification of livestock, it can be divided into pig casings, sheep casings and cattle casings, and can also be divided into small casings and large casings. It is mainly used as a jacket for filling sausages and enemas, and can also be made into catgut, which is used to make tennis racket strings, bow strings, musical instrument strings, surgical sutures and so on.

China has been processing casings for more than 100 years. Pig casings are mostly produced in East China and Central China, while sheep casings are mostly produced in North China, Northeast China and Inner Mongolia. Originally only used for bowstring and elastic cotton thread, the output is limited. In the early 20th century, factories were set up in Tianjin, Beijing and other places for processing and production, which soon became an important export material of China.