Exploration on the Application of Electrodialysis Technology in Desalination of Soy Peptone

Soy peptone is a light yellow to off-white dry powder obtained through processes such as degreasing, digestion, filtration, concentration, and spray drying of high-quality soybeans. It plays a crucial role in the preparation of microbial culture media, providing essential nutrients for microbial growth. However, during the production of soy peptone, salts are often introduced, leading to high salt content in the product and affecting its application effect. Traditional desalination methods such as concentration crystallization, ion exchange, and solvent desalination have disadvantages like high energy consumption, low separation efficiency, and environmental pollution. As an efficient membrane separation technology, electrodialysis shows great application potential in the desalination of soy peptone.

Principles of Electrodialysis Technology

Electrodialysis is a membrane separation technology that uses an electric field to separate and purify ions in solutions. Its basic principle is to place the solution in an electric field and set up selective ion exchange membranes between the anode and cathode. Cations and anions in the solution move toward the cathode and anode under the electric field, respectively, and are transported out or retained through cation exchange membranes and anion exchange membranes, achieving separation and purification of different ions. In electrodialysis equipment, multiple pairs of cation and anion membranes are typically arranged alternately to form groups of freshwater and concentrated water chambers. The solution is deionized when flowing through the freshwater chambers, while the concentrated water chambers collect and discharge the migrated ions, achieving the purpose of desalination and purification.

Application Advantages of Electrodialysis in Soy Peptone Desalination

High-Efficiency Desalination

Electrodialysis technology can effectively remove salts from soy peptone solutions, reduce salt content, and improve product quality. Compared with traditional methods, electrodialysis can achieve a high desalination rate in a shorter time. For example, in the xylose preparation process, electrodialysis generally treats the solution after the front-end decolorization process, directly replacing ion exchange for deacidification and desalination. The conductivity of the decolorized solution is typically 12–30 mS/cm, and after electrodialysis treatment, the conductivity of the effluent xylose solution is <0.5 mS/cm, with a xylose recovery rate of over 97%. Although the properties of soy peptone solutions differ from xylose solutions, this reflects the high efficiency of electrodialysis in desalination.

Environmental Protection and Energy Saving

As a physical separation method, electrodialysis does not require adding any chemical reagents, causing no environmental pollution and consuming low energy. Traditional desalination methods often use large amounts of chemical reagents for ion exchange or precipitation reactions, which not only generate substantial waste residues and wastewater but also increase treatment costs. Electrodialysis relies solely on the electric field for ion separation, avoiding chemical usage, reducing environmental impact, and lowering production costs due to its relatively low energy consumption.

Continuous Production

Electrodialysis enables continuous production, improving production efficiency and capacity to meet the needs of large-scale industrial production. In soy peptone production, continuous production can enhance efficiency, shorten the production cycle, and reduce costs. Electrodialysis equipment can operate continuously, and by controlling parameters such as feed flow and electric field strength, continuous desalination of soy peptone solutions is achieved.

Process Flow of Electrodialysis in Soy Peptone Desalination

Pretreatment

The raw soy peptone solution undergoes operations such as filtration, impurity removal, and pH adjustment to ensure feed quality and provide qualified raw materials for subsequent electrodialysis desalination. Filtration removes suspended solids and impurities to prevent clogging of ion exchange membranes. Adjusting the pH value makes ions in the solution stay in a suitable state, facilitating ion migration and separation.

Electrodialysis Desalination

The pretreated soy peptone solution is fed into the electrodialysis device, and ion separation and desalination are achieved through the electric field. During this process, parameters such as electric field strength and membrane stack configuration should be adjusted according to the salt concentration, ion types, and desalination requirements of the soy peptone solution to achieve the best desalination effect. For example, within a lower voltage range (14–32 V), the conductivity decreases rapidly and the desalination rate is high before 70 minutes of desalination. Thereafter, the conductivity levels off and the desalination rate decreases. At higher working voltages (38–42 V), the initial decline in conductivity is relatively slow, and the conductivity drops sharply after 70 minutes of desalination. This is because the high current density at high voltages causes concentration polarization, where ions cannot migrate across the membrane, leading to slow conductivity changes and reduced desalination rates. Therefore, reasonable selection of voltage and desalination time is necessary to improve desalination efficiency.

Post-Treatment

The desalinated soy peptone solution undergoes necessary adjustments and optimization, such as pH adjustment and addition of flavoring substances, to obtain the final product meeting requirements. Since the electrodialysis process may affect the solution's pH, adjustments should be made according to product requirements. Meanwhile, flavoring substances can be added as needed to improve the product's taste and quality.

Application Challenges and Countermeasures of Electrodialysis in Soy Peptone Desalination

Membrane Fouling and Service Life

The complex components in soy peptone solutions may cause membrane fouling, affecting electrodialysis efficiency and membrane service life. To alleviate this, the membrane cleaning process and membrane material selection can be optimized. For example, ion exchange membranes should be cleaned regularly to remove surface pollutants. Meanwhile, selecting membrane materials with good anti-fouling properties can extend membrane life.

Cost-Effectiveness

Although electrodialysis has advantages in energy conservation and environmental protection, cost-effectiveness must still be considered for large-scale applications. Technological innovation and process optimization to reduce equipment investment and operating costs are key to improving its competitiveness. For instance, developing new ion exchange membranes to enhance membrane performance and life while reducing costs, and optimizing the electrodialysis process to improve desalination efficiency and reduce energy and reagent consumption.

 

Electrodialysis technology offers advantages such as high-efficiency desalination, environmental protection, energy saving, and continuous production in soy peptone desalination, providing a new solution for soy peptone production. However, in practical applications, issues like membrane fouling, service life, and cost-effectiveness need to be addressed. Through continuous technological innovation and process optimization, electrodialysis is expected to be more widely applied in soy peptone desalination, promoting the sustainable development of the soy peptone industry. In the future, with continuous innovation in membrane materials and process technologies and the expansion of application fields, electrodialysis technology will play a more important role in soy peptone desalination, contributing to the high-quality development of the soy peptone industry.

 

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