As a key force in the traditional fermented food industry, the kimchi industry has seen increasingly prominent wastewater problems during its large-scale production process. This type of wastewater is characterized by high salinity, high organic matter content and complex components, making it a persistent problem that traditional treatment technologies find difficult to overcome. Electrodialysis technology, with its unique electric field-driven membrane separation mechanism, is creating an innovative path for the treatment of pickled vegetable wastewater that combines environmental protection and resource utilization.

I. Industry Bottlenecks in Kimchi Wastewater Treatment: The "Three Major Shackles" of Traditional Technologies
The wastewater from kimchi production has distinct characteristics: high-salt wastewater (with a salt content of 5%-15%) generated during the pickling process, organic wastewater (CODcr 2000-8000mg/L) discharged during the fermentation process, and mixed wastewater from equipment cleaning. Traditional processing technologies are confronted with three core challenges

"Treatment Blind spots" in high-salt environments
When the salinity exceeds 1%, the microbial activity in the activated sludge process will drop sharply by more than 60%, resulting in a significant decline in treatment efficiency. A certain pickled vegetable enterprise adopted the traditional A/O process to treat high-salt wastewater, but the COD removal rate was less than 30%, far from meeting the design standard.

The "hidden loss" of resource waste
Valuable substances such as sodium chloride and lactic acid contained in the wastewater have not been recovered, resulting in the loss of tens of thousands of tons of salt resources every year. Take a large-scale pickled vegetable base in Sichuan as an example. The salt content of its annual discharged wastewater is equivalent to the market value of 3,000 tons of industrial salt.

The "potential risk" of secondary pollution
Heavy metal-containing sludge produced by chemical precipitation and excess activated sludge generated by biological treatment can easily pollute soil and groundwater if not properly disposed of. Due to leakage at the sludge storage site of a certain enterprise, 200 mu of farmland around it has suffered from salinization.

Ii. Principle of Electrodialysis Technology: Decoding the "Physical Mechanism" of High-Salt Wastewater
The core of electrodialysis technology is to drive the directional migration of ions with a direct current electric field and achieve solution separation through the selective permeability of ion-exchange membranes. Its working mechanism involves three key dimensions:

"Ion migration driven by electric field
Under the action of an electric field intensity of 2-3V/cm, charged ions such as Na? and Cl? in the wastewater move towards the opposite electrodes at a speed of several millimeters per second. Cations enter the concentration chamber through the cation membrane, while anions enter the adjacent concentration chamber through the anion membrane, thus achieving the separation of substances between the fresh water chamber and the concentration chamber.

The "screening effect" of membrane separation
Homogeneous ion-exchange membranes are designed with molecular-level channels, allowing only ions with a diameter of less than 0.3nm to pass through while intercepting macromolecular organic substances (such as proteins and polysaccharides) and colloidal particles. This physical barrier effect enables the electrodialysis system to maintain an organic matter retention rate of over 90% when treating pickled vegetable wastewater.

"Acid-base conversion" of bipolar membranes
The bipolar membrane composed of an anion exchange layer, a cation exchange layer and a hydrophilic interface can efficiently dissociate water molecules at a voltage of 1.5-2.0V, generating H? and OH?. This feature enables the electrodialysis system to directly convert sodium lactate into lactic acid and sodium hydroxide, achieving on-site regeneration of acid-base resources.

Iii. Innovative Application Scenarios of Electrodialysis in the Kimchi Industry
The concentration process for the "resource utilization" of high-salt wastewater
For kimchi pickling wastewater, the electrodialysis system, through a multi-stage series design, can gradually concentrate the salt content from 8% to over 20%. A certain enterprise adopted a combined process of "pretreatment + electrodialysis + MVR evaporation". After the electrodialysis section concentrated the salt by four times, the energy consumption of the MVR evaporator was reduced by 40%, saving 1.2 million yuan in steam costs annually. The concentrated salt solution can be refined and reused as industrial salt, forming a closed-loop circulation system of "wastewater - concentrated salt - industrial salt".

2. "Precise Separation" of Organic Substances and Salts
Facing the lactic acid-salt coexistence system in kimchi fermentation wastewater, the newly developed organic pollution-resistant ion-exchange membrane forms a "hydration layer - repulsion layer" double structure on the membrane surface through surface modification technology. This design enables the membrane to maintain an ion removal rate of over 85% when treating wastewater containing 5% organic matter, breaking through the technical bottleneck of traditional membrane technology that is prone to organic pollution.

3. In-situ Regeneration of Lactic Acid Resources
Bipolar membrane electrodialysis technology provides a new path for the recovery of lactic acid in pickled vegetable wastewater. In a certain pilot-scale project, the system converted wastewater containing sodium lactate into a 15% lactic acid solution, with a recovery rate of 90%. Meanwhile, the by-product sodium hydroxide solution could be used for equipment cleaning. Compared with the traditional calcium salt precipitation method, this process reduces the generation of solid waste by 85% and lowers the cost of treating each ton of wastewater by 300 yuan.

4. "Gradient Reuse" of Cleaning wastewater
The cleaning of kimchi production equipment will generate wastewater with stepped concentrations (COD 500-5000mg/L). The electrodialysis system adopts a staged treatment mode to treat low-concentration wastewater to the reuse standard (COD<100mg/L), which is used for cleaning the workshop floor. High-concentration wastewater is concentrated and then enters the biochemical treatment unit. This hierarchical reuse model has reduced the enterprise's fresh water consumption by 60%, saving 800,000 yuan in water fees annually.

Iv. Technological Upgrade: The Iterative Direction of Electrodialysis
To meet the strict process requirements of the kimchi industry, electrodialysis technology is continuously evolving in the following directions:

"Performance Innovation" of Membrane Materials
The surface resistance of the graphene-modified ion-exchange membrane was reduced to 2Ω · cm², and the ion flux increased by 40%. The 3D printed flow channel design increases the membrane flux to 250LMH and enhances the anti-pollution performance by two times. These innovations have significantly enhanced the operational stability of the electrodialysis system when treating high-viscosity kimchi wastewater.

"System Optimization" of process integration
The electrodialysis is coupled with membrane bioreactor (MBR), ozone catalytic oxidation and other technologies to form the "electrodialysis - MBR" combined process. A certain enterprise adopted this process to treat mixed wastewater, achieving a COD removal rate of 95%, and the effluent quality met the first-level A standard of the "Integrated Wastewater Discharge Standard".

"Digital Upgrade" of intelligent control
Introduce machine learning algorithms to monitor parameters such as membrane voltage and current density in real time and dynamically adjust operating conditions. A certain intelligent control system, by predicting the trend of membrane fouling and initiating the backwashing program in advance, has extended the membrane's service life to over three years and reduced maintenance costs by 50%.

V. Industry Impact: From End-of-pipe Treatment to Green Transformation of the Entire Industrial Chain
The promotion and application of electrodialysis technology is driving the pickled vegetable industry to transform towards a "resource recycling" model

Improvement in economic benefits: After a large-scale pickled vegetable enterprise applied electrodialysis technology, it saved 2 million yuan in salt purchase costs annually, recovered lactic acid and created a value of 1.5 million yuan, with the overall economic benefits increasing by 30%.
Environmental risks have been reduced: The reuse rate of wastewater has risen to over 85%, the generation of hazardous waste has decreased by 75%, and the enterprise's environmental credit rating has been upgraded from B to A.
Enhanced industrial competitiveness: By building a differentiated advantage through resource recycling, it helps enterprises break through international green trade barriers, and the export volume of products has increased by 25% year-on-year.
Electrodialysis - The green transformation engine for the kimchi industry
Under the dual drive of the "dual carbon" goals and food safety policies, electrodialysis technology, with its core advantages of high efficiency, low carbon and resource utilization, has become a technical benchmark in the field of pickled vegetable wastewater treatment. From the concentration treatment of high-salt wastewater to the in-situ regeneration of lactic acid resources, from the optimization of intelligent control systems to the green upgrade of the entire industrial chain, this technology is reshaping the ecological model of kimchi production. With the continuous breakthroughs in membrane material science and intelligent control technology, electrodialysis is bound to play a core role in the sustainable development of the pickled vegetable industry and promote the transformation of traditional industries towards modern green manufacturing.