Food industry has a wide range of raw materials, a wide variety of products, effluent water quantity, water quality is very different.
The main pollutants in the wastewater are
(1) solid substances floating in the wastewater, such as vegetable leaves, peel, meat, poultry feathers, etc.
(2) suspended substances in wastewater include grease, protein, starch, colloidal substances, etc.;
(3) acid, alkali, salt and sugar dissolved in waste water;
(4) pathogenic bacteria and so on.
Food industry wastewater is characterized by high content of organic substances and suspended solids, easy to decay, and generally no great toxicity.
Its harm is mainly to make water eutrophication, which causes the death of aquatic animals and fish, and causes the organic matter deposited in the bottom of the water to produce odor, worsen the water quality and pollute the environment.
In addition to proper pretreatment according to water quality characteristics, biological treatment is generally suitable for wastewater treatment in food industry.
If the effluent water quality requirements are high or the content of organic matter in wastewater is high, two-stage aeration tank or two-stage biological filter tank, or multi-stage biological turntable can be adopted.
Or a combination of two biological treatment devices, or anaerobic - aerobic series of biological treatment system.