Membrane Separation Technology for Fermentation Broth Purification and Protein Recovery

Biological fermentation industry is an important pillar of modern bio‑manufacturing, covering amino acids, functional proteins, microbial polysaccharides, enzyme preparations and biochemical raw materials. After tank fermentation and cultivation, the original fermentation liquid is a heterogeneous and complex system. The valuable components include target proteins, biological enzymes and small‑molecule active metabolites, while the invalid impurities contain residual mycelium, broken cell debris, denatured miscellaneous proteins, colloidal macromolecules and soluble inorganic salts. If these impurities cannot be removed efficiently in the early stage, they will cause turbidity of feed liquid, low product purity, easy deterioration and short storage life, seriously restricting the quality and commercial value of fermentation products.

Traditional fermentation broth purification processes have obvious technical defects and resource waste problems. Centrifugal separation can only remove large‑particle mycelium slag, but cannot separate soluble miscellaneous proteins and micro‑colloids, resulting in high impurity content in the supernatant. Plate‑frame filtration and bag filtration rely on filter media interception, which easily causes clogging, requires frequent replacement of consumables, and leads to serious loss of active protein components. In addition, traditional processes often require high‑temperature concentration and chemical precipitation, which destroy the spatial structure of biological proteins, reduce enzyme activity, and produce a large amount of waste water and solid waste, failing to meet the requirements of energy‑saving and environmentally friendly production.

Graded membrane separation technology completely solves the technical bottlenecks of traditional fermentation broth treatment. According to the molecular weight difference between target proteins and miscellaneous impurities, the system adopts staged membrane filtration to realize precise classified separation. The pretreatment ultrafiltration membrane effectively intercepts mycelium debris, macromolecular denatured proteins and colloidal pollutants, thoroughly removing macroscopic and microscopic impurities in the fermentation liquid and improving feed liquid clarity. The fine nanofiltration membrane further removes small‑molecule inorganic salts, residual pigments and heterozygous organic acids, realizing deep desalination, decolorization and low‑temperature concentration of active protein components.

The entire membrane refining process is carried out at normal temperature and low pressure without heating, chemical additives and organic solvent participation. The mild physical separation environment completely protects the biological activity of functional proteins and enzyme preparations, avoiding activity degradation and structural denaturation caused by high temperature and chemical treatment. Different from traditional processes with high material loss, the membrane separation process features high interception accuracy and high recovery rate, which maximizes the retention of effective active ingredients and significantly improves the comprehensive yield of fermentation products.

Adopting cross‑flow circulating operation mode, the membrane system forms continuous high‑speed scouring on the membrane surface, which effectively inhibits the deposition of protein colloids and suspended impurities, slows down membrane fouling speed, and ensures long‑term stable filtration flux and separation efficiency. Equipped with automatic CIP cleaning system, the equipment can regularly clean organic dirt and protein adsorption layers, quickly restore membrane permeability, and realize uninterrupted 24‑hour continuous production. The fully automatic PLC intelligent control system can adjust operating pressure, flow rate and concentration multiple according to different fermentation broth characteristics, adapting to the purification and concentration requirements of various fermentation products.

In standardized fermentation production lines, the membrane separation process forms a complete closed‑loop refining workflow: original fermentation broth → centrifugal coarse slag removal → ultrafiltration precision clarification and impurity removal → nanofiltration desalination, decolorization and concentration → finished protein liquid or metabolite concentrate. This graded treatment process thoroughly separates invalid impurities and effective components, effectively reducing the ash content and chroma of finished products, improving product solubility and storage stability, and realizing high‑value recovery of biological proteins.

Compared with traditional processes, membrane separation technology has outstanding advantages such as high purification accuracy, low energy consumption, no secondary pollution and high resource utilization rate. It eliminates the consumption of filter cloth, filter aids and chemical reagents, reduces wastewater discharge and solid waste generation, and greatly cuts enterprise operating costs. The recycled high‑purity protein and active metabolites can significantly improve the economic added value of fermentation products, while the clean permeate water can be reused for fermentation batching and workshop circulation water, realizing resource recycling and green low‑carbon production.

With the rapid upgrading of the biological fermentation industry towards high efficiency, high purity and green environmental protection, membrane graded separation technology has become an indispensable core process for fermentation broth deep refining and protein resource recovery. It provides a mature, stable and energy‑saving technical solution for modern bio‑manufacturing enterprises to achieve quality improvement, yield increase and cost reduction.