This equipment is a terminal deep treatment system for high-purity water preparation. Through the combination process of “EDI (continuous electric desalination)+nuclear grade polishing mixed bed”, the pre treated pure water (conductivity ≤ 50 μ S/cm) is further purified to ultra pure water level (conductivity ≤ 0.055 μ S/cm, i.e. resistivity ≥ 18.2M Ω· cm). It is widely used in scenarios that require extremely high water purity, such as nuclear power, semiconductors, pharmaceutical GMP, etc. The following will explain the system composition, working principle, core advantages, and application scenarios:
1、 Core components and functions of the system
1. EDI module (Electrodeionization)
Construction: Composed of alternating cation exchange membranes, anion exchange membranes, ion exchange resins (mixed bed resins), electrodes (titanium coated ruthenium), and water flow channels, the overall package is a modular unit (common specifications: water production capacity of 0.5-50m ³/h).
Core role:
Deep desalination: Under the action of direct current, cations (Na ⁺, Ca ² ⁺, etc.) in water migrate to the cathode, anions (Cl ⁻, SO ₄ ² ⁻, etc.) migrate to the anode, enter the concentrated water chamber through the ion exchange membrane and be discharged, while the resin continues to regenerate in the electric field (without the need for chemical agents);
Reduce conductivity: treat the incoming water (RO produced water, conductivity 10-50 μ S/cm) to 0.1-0.5 μ S/cm (resistivity 2-10M Ω· cm), and remove more than 99% of soluble salts;
Replacing traditional mixed beds: No need for acid-base regeneration, avoiding chemical pollution, and achieving continuous and stable water production.
2. Nuclear Grade Polishing Mixed Bed
Structure: stainless steel pressure tank (316L material), filled with nuclear grade gel type ion exchange resin (positive resin 001 × 7MB and negative resin 201 × 7MB are mixed at a ratio of 1:2), the resin particle size is uniform (0.45-0.65mm), and the soluble organic matter (TOC ≤ 5ppb) is removed through strict cleaning.
Core role:
Terminal refinement: Retain trace ions (such as ppb level Na ⁺, SiO ₂) remaining in EDI produced water, reduce conductivity to * * ≤ 0.055 μ S/cm * * (resistivity ≥ 18.2M Ω· cm), and achieve ultra pure water standards;
Removing trace pollutants: adsorbing trace organic matter, colloids, and metal ions dissolved in water to ensure that water quality meets the stringent requirements of nuclear industry and electronic grade water;
Stable water quality fluctuations: As the “polishing” stage of the EDI system, it buffers the fluctuations in incoming water quality and ensures long-term stability of effluent purity.
3. Auxiliary system
Precision pre-processing unit:
5 μ m security filter (intercepting a small amount of resin fragments discharged from EDI);
UV sterilizer (optional, wavelength 254nm, kills microorganisms and avoids contaminating the polishing mixed bed).
Control system:
PLC+touch screen, real-time monitoring of inlet and outlet water conductivity, flow rate, pressure and other parameters;
When the water resistance rate of the polishing mixed bed outlet is less than 15M Ω· cm, an automatic alarm prompts to replace the resin;
Automatic shutdown protection for EDI module in case of water shortage or overvoltage.
2、 Workflow
Pre treated influent: The water produced by the front-end RO system (conductivity ≤ 50 μ S/cm) first enters a 5 μ m security filter to remove small particles and protect the EDI module.
EDI deep desalination: Water enters the EDI module, and under the action of direct current and ion exchange resin, most of the ions are migrated to the concentrated water chamber and discharged. The produced water (conductivity 0.1-0.5 μ S/cm) enters the next stage.
Nuclear grade polishing and refining: EDI produced water enters the nuclear grade mixed bed, and residual trace ions are adsorbed by resin, ultimately producing ultrapure water (resistivity ≥ 18.2M Ω· cm), which is stored in the ultrapure water tank or directly supplied to users.
Monitoring and maintenance: The system monitors water quality in real-time. When the pressure of EDI concentrate is abnormal or the mixed bed fails, it automatically alarms and prompts maintenance (such as EDI cleaning, mixed bed resin replacement).
3、 Core advantages and technological features
1. The water quality has extremely high purity
The final water resistance rate is ≥ 18.2M Ω· cm (25 ℃), the total organic carbon (TOC) is ≤ 10ppb, and the particle number (≥ 0.1 μ m) is ≤ 1/ml, fully meeting ASTM D1193-19 (electronic grade water standard) and GB/T 11446.1-2013 (electronic grade water specification).
2. Efficient and environmentally friendly operation
No need for chemical regeneration: The EDI module achieves resin self regeneration through an electric field, and the nuclear grade mixed bed has a long service life (generally running for 6-12 months), reducing acid and alkali consumption and wastewater treatment costs, meeting environmental requirements.
Continuous and stable water production: Compared with traditional intermittent regeneration mixed beds, the system can operate continuously for 24 hours, and the fluctuation of water quality is ≤± 0.5M Ω· cm.
3. Nuclear grade reliability
The nuclear grade mixed bed resin has undergone radiation stability testing (resistance to gamma radiation dose ≥ 10 ⁶ Gy) and can still maintain its exchange performance in radiation environments such as the nuclear industry;
The equipment material (316L stainless steel, fluororubber seals) has strong corrosion resistance, avoiding leaching and polluting water quality.
4. Intelligent control
Real time display of resistivity, flow rate, and pressure curves, supporting data storage and remote monitoring (optional 4G/Ethernet module);
Automatically determine resin failure status, reduce manual inspection costs, suitable for unmanned precision workshops.
4、 Typical application scenarios
Nuclear industry: coolant replenishment water for the primary and secondary circuits of nuclear power plants, fuel rod cleaning water (requiring extremely low ion content to prevent equipment corrosion).
Semiconductor manufacturing: The water used for chip lithography and etching processes must be free of any ions and particles to avoid affecting circuit accuracy.
High end pharmaceuticals: Injection water and genetic engineering water used in biopharmaceuticals require the removal of all microorganisms and pyrogens (endotoxins ≤ 0.03EU/ml).
Laboratory analysis: Experimental water for precision instruments such as ICP-MS (Inductively Coupled Plasma Mass Spectrometry) and HPLC (High Performance Liquid Chromatography) to ensure accurate detection results.
summarize
The EDI+nuclear grade polishing mixed bed system is the “ultimate solution” for ultrapure water preparation, which achieves efficient conversion from pure water to ultrapure water through the combination of “electrically driven desalination+nuclear grade resin polishing”. Its core values lie in high purity, environmental friendliness, and stability, especially suitable for cutting-edge industries and scientific research fields that have extreme requirements for water quality. It is a typical representative of modern high-purity water treatment technology.
Post time: Jul-16-2025