Lactic acid, citric acid, etc. are all organic acids, and are extremely important chemical products. For example, lactic acid polymer polylactic acid is the most promising biodegradable biomaterial, which will replace polyethylene and polypropylene plastics, eliminate the pollution of "white plastic" to nature, and deal with the problems caused by the reduction of resources such as oil.

There are many ways to produce organic acids, but the most promising one is bio-fermentation. Bio-fermentation is to use starch, cellulose, glucose, sucrose, milk or other waste materials that can be used by microorganisms as raw materials, and use bacteria or other microbial fermentation methods to produce organic acids and their derivatives.

Organic acids produced by fermentation are generally low in concentration and accompanied by impurities, and extraction and separation of organic acids is an effective means of extraction, separation and concentration.