The food industry has a wide range of raw materials and many kinds of products. The quantity of waste water and water qualiyare very dfferent. The main pollutants in the wastewater are 1 floating solid substances in the wastewater, such as broken meat,poulry feathers, etc. (2) Ol, protein, starch, colloid and so on are suspended in the waste water; (3) acids, bases, salts andsugars dissolved in. wastewater; 4sediment and other organic matter contaned in raw materials; Food industry wastewater ischaracterized by high oontent of organic mater and suspended solids, easy to corrupt, and generally no toxicity, its harm ismainly to eutrophication of water body, resuting in the death of aquatic animals and fish. Organic matter that causes depositionunder the water Produce stink, worsen water quality and pollute the environment.
In addtion to proper pretreatment according to the characteristics of water qualty, bialogical treatment is generally suitable forfood industry wastewater treatment, such as high requrement tor ffluent quaity or high content of organic matter in wastewater.Two- stage aeration tank or two-stage biofter, or multi- stage b ofilter, or combined use of two biological treatment devices, oraneerobic aerobic senes biological treatment system can be used.