Application of Membrane Separation Technology in the Field of Amino Acids

Amino acids are the basic units that make up proteins. They are used more and more widely in food, cosmetics, medicine and so on and their demand continues to increase. At the same time, due to intensified industry competition, it is urgent to continuously improve existing technologies and develop new technologies to reduce production costs. In this form, membrane separation technology is becoming one of the hot spot for development and application in terms of clarification and removal of bacteria from amino acid fermentation broth, desalination and concentration of mother liquor, and purification of amino acid products due to its energy-saving, high-efficiency, and non-phase-change characteristics.

Traditional solid-liquid separation equipment such as plate frame, vacuum drum, centrifuge and diatomite machine are still used for sterilization and filtration of most fermentation broth. These methods can only roughly separate the mycelium, solid impurities and other solids in the fermentation broth, but can’t separate a large number of soluble proteins, colloids, impurity polysaccharides and small particle insoluble substances in the fermentation broth. Filtrate transmittance is low, which improves the extraction difficulty of the subsequent process, and will affect the quality and yield of the final product; At the same time, these traditional processes have the disadvantages of many extraction steps, high labor intensity and low product yield. The new generation fluid separation process based on inorganic ceramic membrane technology with its unique technical advantages has gradually become one of the best ways to solve this problem.

Ⅰ. Application of membrane separation technology in amino acid field

Application of threonine in fermentation broth extraction: There are a lot of bacteria and miscellaneous proteins in threonine fermentation broth. The existence of these substances reduces the yield and crystallization quality of threonine. Therefore, threonine must be removed before crystallization. The traditional process mainly adopts flocculation method, and the bacteria are precipitated by flocculant. Due to the high content of bacteria in the fermentation broth, the use of flocculant is large, and the flocculant has strong adsorption, some amino acids are adsorbed in the process of adsorption and sedimentation, which reduces the yield of threonine; At the same time, new impurities are introduced, which makes the subsequent technology treatment more difficult. Using ceramic membrane to separate bacteria in fermentation broth can not only avoid the use of flocculant and reduce the treatment pressure of subsequent technology, but also operate conveniently, which is suitable for large-scale industrial production.

Application of tryptophan fermentation broth in extraction and purification: In the traditional tryptophan extraction technology, diatomite needs to be added during plate and frame filtration, and the collection rate of diatomite is about 85%. The recovery value of plate and frame filtration diatomite is very low. The traditional tryptophan extraction technology has high energy consumption and high cost. The overall extraction rate of tryptophan is less than 80%, so it must be optimized. In the tryptophan extraction technology, membrane technology is applied to improve the fermentation broth in the traditional extraction technology. The protein bacteria in the tryptophan fermentation broth are filtered by ceramic membrane, the fermentation broth is cleared, and then the pigment and macromolecular protein in tryptophan are removed by decolorization membrane. Finally, the tryptophan yield can reach 98% by using concentrated membrane in normal temperature environment. Membrane separation technology shows great advantages in tryptophan extraction technology.

Application of glutamic acid crystallization mother liquor to recover glutamic acid: there is still a large amount of glutamic acid in the glutamic acid crystallization mother liquor, and direct discharge will cause the loss of glutamic acid. The mother liquor is treated with ceramic membrane, and the glutamic acid is adsorbed and analyzed with cation exchange resin, and the solution is recrystallized, which improves the yield of glutamic acid and creates higher value for the enterprise.

Ⅱ. Characteristics of membrane separation technology

1. The ceramic membrane has high separation precision and high filtrate transmittance, can reduce the pollution of subsequent ion exchange resin and vacuum concentration, and improves the product quality.

2. Pure physical process, no phase transition, good stability and not easy to destroy product components.

3. Without additional additives, the concentrated intercepting solution of ceramic membrane such as bacterial protein, can be used for feed recovery.

4. Organic membrane can concentrate amino acids with low energy consumption and simple operation. At the same time, it can remove some salt and improve product quality.

5. High degree of automation, simple and reliable operation, greatly reducing labor intensity.