Bioengineering covers many fields such as fermentation engineering, biopharmaceutical, environmental protection, plant biotechnology and bio-chemical industry. It is a new comprehensive applied discipline with wide application prospects. In bioengineering, solvent extraction as a basic chemical unit operation, its application is also very wide. This issue mainly introduces the application of centrifugal solvent extraction in bioengineering, especially in the purification of lactic acid.

Lactic acid, as an important organic acid, exists widely in human body, animal and plant. Lactic acid and its salts and derivatives are widely used in food, feed, chemical industry and medicine. Lactic acid is usually produced by fermentation, which mainly includes three processes of strain culture, fermentation and separation and purification, among which separation and purification is the key link to ensure the purity, yield and quality of the product.

At present, the separation and purification methods of lactic acid include crystal separation, adsorption, membrane separation, molecular distillation and solvent extraction. High purity lactic acid can be obtained by crystallization, but the yield is low. It is difficult to obtain high purity products by adsorption method. Molecular distillation method has low yield and high equipment investment. In contrast, the solvent extraction method is relatively simple to operate and can obtain high purity lactic acid, which has obvious advantages, but it needs to choose the appropriate extraction agent.

At present, extractants used for lactic acid purification include n-butanol, trialkyl phosphorus oxide, butyl phosphate and trioctylamine, etc. Through multi-level tandem countercurrent operation, the process flow of extraction - reverse extraction - regeneration - oil-water separation is formed. The extraction rate is high, the extraction agent can be recycled and recycled, and the operation and maintenance cost is low. Engineering practice has proved that centrifugal solvent extraction is an effective method to prepare high purity lactic acid.

The application of centrifugal solvent extraction in lactic acid purification, because of its excellent separation effect and economy, has shown broad application prospects in the field of bioengineering.

** Application of combined extraction centrifugal extractor in essence production **

Flavor is a substance used for flavoring or adding aroma, which is widely used in food, beverage, cosmetics, cleaning supplies and other industries. The production process of essence includes the steps of raw material preparation, extraction and concentration, blending and mixing, filtration and purification, stabilization and storage. Among these steps, the purification process is particularly critical. Solvent extraction has become the main method of essence purification due to its advantages of high extraction rate and low energy consumption.

The application of combined extraction centrifugal extractor in essence purification is particularly prominent. The equipment is composed of three stage countercurrent extraction, one stage pickling system and three stage washing system in series to achieve efficient purification. The pH value of the material system is adjusted by acid solution, and the material of the combined extraction centrifugal extractor is made of steel-based spray fluorine plastic, which is not only acid-resistant, but also reduces the equipment cost, so as to obtain good purification effect.