EDI is a new type of water treatment method that combines electrodialysis (the scene where the charged solute particles in the solution migrate through the membrane under the influence of an electric field) and ion exchange.

Laboratory water purification system is one of the commonest equipment for scientific researchers, mainly used to produce ultrapure water for experiments. The great importance of ultrapure water is obvious in that water is an essential and numerously used reagent in the experiment process.

EDI is a replacement technology for the traditional ion exchange mixed bed process. The emergence of EDI is an advancement in water treatment technology, marking that the water treatment industry has entered the ranks of the green industry. It organically combines traditional electrodialysis technology and ion exchange technology to continuously produce high-quality pure water, but does not need to use acid or alkali, completely get rid of the problems of acid and alkali consumption, chemical waste liquid pollution, etc., so as to truly achieve Clean Production.

As a kind of deionized water equipment, the laboratory ultrapure water machine primarily adopts solutions such as reverse osmosis(RO), electrodialysis, ion exchange, and EDI. Among them, electrodeionization (EDI), is a new type of pure water and ultrapure water treatment technology gradually developed in the history of pure water production technology. The emergence of EDI is revolutionary progress, marking that the water treatment industry has finally entered the league of the green industry.

The advanced technology is rapidly gaining acceptance by virtue of good environmental protection and accessible operation, which has come into wide application in pharmaceuticals, electronics, electric power and chemical industry, etc.

What is EDI?

Electrodeionization, abbreviated as EDI, scientifically integrates electrodialysis and ion exchange technology into one to remove ionized species from water. This process combines ion-exchange resins and ion-selective membranes, which are used to move ionic impurities into a waste or concentrate water stream, leaving purified product. As impurities leave via the concentrate water stream, their buildup does not exhaust the resin, and it prolongs the resin lifespan. Water resistivity of >15 MΩ-cm may be achieved by using this process.

How EDI works

The EDI device fills and sandwiches the ion exchange resin between the anion and cation exchange membranes to form an EDI unit. The working principle of EDI is shown in the figure below. In the EDI module, a certain number of EDI units are separated by a mesh to form a concentrated water chamber. In addition, cathode and anode electrodes are arranged at both ends of the unit group. Driven by the direct current, the anions and cations in the water flow through the fresh water chamber respectively pass through the anion and cation exchange membrane into the concentrated water chamber and are removed in the fresh water chamber. The water passing through the concentrated water chamber takes the ions out of the system and becomes concentrated water. EDI equipment generally uses reverse osmosis (RO) pure water as EDI feed water. The conductivity of RO pure water is generally 2-40μS/cm (@25℃). The resistivity of EDI pure water can be as high as 18 MΩ.cm (25°C), but according to the use of deionized water and system configuration settings, EDI pure water is suitable for the preparation of pure water with a resistivity requirement of 10-15MΩ.cm (25°C)


EDI has the following advantages,compared with mixed ion exchange technology

The process flow of the laboratory ultrapure water machine is generally as follows: Pretreatment—High pressure pump—RO membrane—Ion exchange column (or EDI)—UV lamp—Ultrafiltration (or microfiltration)- –Terminal filter.

Compared with ion exchange technology, EDI as a new technology has the following advantages:

  1. Stable water quality
  2. It is easy to realize fully automatic control
  3. No shutdown due to regeneration
  4. No need for chemical regeneration
  5. Low operating cost
  6. No sewage discharge

The main factors restricting the promotion of EDI in the laboratory

  1. The user is worried that the early purchase cost of EDI ultrapure water machine is relatively high
  2. Worry about the service life of EDI
  3. The user is worried that the EDI replacement cost is too expensive

Why advocate EDI unit? Low maintenance!

Normally, we first perform reverse osmosis and then remove the remaining impurities by ion exchange resin on raw water when using a laboratory water purification system. Therefore, for any industry laboratory, reverse osmosis membrane and ion exchange resin are both consumables. When the ion exchange resins are about to be depleted, they begin to release weakly ionized substances including some phosphates, silicates and nitrates. And if the colour of the resins has changed, we recommend immediate replacement because the resins, in this case, have lost their ion exchange function.

The above chart depicts the tendency of water resistivity value to change over time in the case of deionization. When the water resistivity drops to the lowest point, it means that the water quality has also become pretty awful. That is, we need to replace the resin directly. Besides, we can also see that the frequency of resin replacement is fairly high.

While in EDI water purification equipment, under the action of a direct-current electric field, water is ionized into H+ and OH- ions to continuously regenerate the resin filled in the bottom layer, so the water quality is properly guaranteed to be constant. As a result, the longer the resin replacement cycle, the lower its frequency. It is the non-complicated water purification process that greatly simplified the labour intensity, easy training within the trainee to accept.

Advantages of EDI unit:

No regeneration chemicals

There is no need to collect, store and dispose of hazardous chemical wastewater. As a result, the new EDI process greatly simplifies the system compared to conventional processes.

Stable water quality

Ion exchange and regeneration are synchronized with the EDI water system so that the water quality is very stable. Unlike mixed beds, the effluent quality is affected by ion leakage at the beginning and end of each regeneration cycle.


The production of electric desalination is continuous, eliminating the need for complex regeneration operations during the mixing process and reducing many spare types of equipment. There is no need to set up operators and operating procedures related to the recycling work.

Low operating cost and maintenance

EDI equipment requires only electricity to operate, while mixed bed technology requires extra acid and alkali. Therefore, ultra-pure water equipment reduces operating costs by saving acid and alkali. No exchange of spent resins or cartridges saves cost.

Smart NE Ultrapure Water Machine allows you easy purchasing , assuring use and low cost

  1. Easy to buy: Heal Force EDI is independently developed and produced. Users can purchase a HealForce EDI ultrapure water machine with the budget of originally purchasing first-tier domestic brand resin type ultrapure water machine. For details, please consult local Heal Force sales support staff.
    The EDI of Heal Force ultrapure water machine is independently developed and produced, and the cost is controllable. If It is purchased during the event period, it has a two-year warranty. It is worry-free to help you achieve easy purchase, rest assured use, and low cost.
  2. Use with confidence: EDI purchased during the activity period has a two-year warranty and worry-free use.
  3. Low cost: EDI is independently researched and developed, and the cost is controllable, and the average annual cost of consumables is equivalent to that of the original resin-type ultrapure water machine (when the user maintains normally and replaces consumables in time).

Heal Force EDI Ultrapure Water Machine Recommendation

Smart Plus NET Ultrapure Water System


1) 5.0 inch color touch screen
2) 30/60L multifunctional water tank
3) Built-in TOC online detector
4) Ultra-pure column for reducing organic matter
5) Independent research and development of EDI device
6) Mobile water dispenser with parameter display

Smart NE Ultrapure Water System


1) Large-screen LCD multi-parameter display
2) All-plastic mold production, beautiful appearance
3) Independent research and development of EDI device
4) 30/60L multifunctional water tank
5) Standard mobile water dispenser

Water Purification Solution(with EDI Unit) by Heal Force


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