An Article to Fully Understands What is a Deionization System


Deionization systems are useful in a variety of applications, including purifying water for drinking, industrial processes, and laboratory use. However, many people may not fully understand what a deionization system is or how it works.

In this article, we will provide an overview of deionization systems and explain how they can be used to effectively eject undesirable ions from water to yield purified water.

Figure 1 Deionization system.

What is a Deionization System?

A water deionization system is a sort of water purification system that eliminates ions, or charged particles, from water. This procedure is frequently used to purify water for drinking as well as for use in industrial, medical, and scientific purposes. Deionizing water can be accomplished in a few different ways, such as:

  • Ion exchange: This method involves passing the water through a bed of ion exchange resin, which removes ions from the water and replaces them with other ions.
  • Distillation: This procedure involves boiling the water, collecting the steam, and condensing it back into a liquid. Because the ions in the water are left behind as the water evaporates, the resulting condensate is free of ions.
  • Reverse osmosis: In order to remove ions and other contaminants from the water, this technique uses a semi-permeable membrane.

Deionized water is typically used in applications where the presence of ions could interfere with the desired outcome, such as in the production of pharmaceuticals, electronics, or in certain chemical reactions.

What is a Deionization System

Parts of a Water Deionization System

To remove ions from water and provide high-purity, demineralized water, a water deionization system consists of a number of parts that act in concert. These elements consist of a pretreatment system, an exchange resin, a mixer, an exchange tank, a regeneration system, a control system, and storage tanks.

· Pretreatment System

Before water is deionized, it typically goes through a pretreatment system to remove any large particles or contaminants that could clog or damage the deionization system. This may include sediment filters, sand filters, or carbon filters.

· Ion Exchange Resin

The main component of a water deionization system is the ion exchange resin, which is a type of bead-like material that removes ions from the water. The resin is typically made of a polymer that is charged with either a positive or negative charge. When water passes through the resin, the ions in the water are attracted to the opposite charge on the resin and are removed from the water.

Figure 2 Ion exchange resin.

· Mixer

A mixer is used to evenly distribute the ion exchange resin throughout the water. This helps to ensure that all of the ions in the water come into contact with the resin and are removed.

· Ion Exchange Tanks

The ion exchange resin is typically contained in one or more tanks, which are connected in series. Water flows through the tanks, and the ions in the water are removed by the resin as it passes through.

· Regeneration System

The ion exchange resin can become exhausted over time and needs to be regenerated to remove the ions that have been removed from the water. This is typically done using a regeneration system, which involves flushing the resin with a strong acid or base to remove the ions and restore the resin to its original state.

· Control System

A water deionization system typically has a control system to monitor the performance of the system and ensure that it is operating correctly. This may include sensors to measure the quality of the water, alarms to alert the operator if there are any problems, and automated control systems to adjust the flow of water through the system.

· Storage Tanks

The purified water produced by the water deionization system is typically stored in one or more tanks until it is needed. These tanks may be equipped with filters or UV lamps to ensure that the water remains pure until it is used.

Figure 3 Two-bed deionizer.

Types of Deionization Systems

(1)Two-Bed Deionization System

In a two-bed deionization system, water is passed through two columns or tanks that contain a bed of ion exchange resin. The resin is typically made of a synthetic material that is specifically designed to attract and remove ions from the water. As the water flows through the columns, the ions in the water are attracted to the resin and exchanged with ions that are already bound to the resin.

The first column is typically filled with a resin that is charged with a positive ion, such as hydrogen or sodium. This resin is used to remove positively charged impurity ions, such as iron and magnesium, from the water. The second column is filled with a resin that is charged with a negative ion, such as hydroxide or carbonate. This resin is used to remove negatively charged impurity ions, such as chlorine and bicarbonate from the water.

After the water has passed through both columns, it will be almost completely free of ions and will be considered deionized water. This water can then be used for a variety of applications, depending on the specific needs of the user.

Two-Bed Deionization System

Pros of Two-Bed Deionization Systems
  • High-purity water: Two-bed deionization systems are capable of producing water with a very low concentration of ions, making it highly pure.
  • Customization: Two-bed systems can be customized to produce water with specific conductivity levels, depending on the specific needs of the application.
  • Efficient: Two-bed systems are efficient at removing ions from water, making them a cost-effective choice for producing high-purity water.
  • Low maintenance: These systems require minimal maintenance, as the resin beds can be regenerated and reused multiple times.
  • Compact size: Two-bed deionization systems are relatively small and can be easily installed in a variety of locations.
  • Versatility: These systems can be used in a wide range of applications, including industrial, laboratory, and residential settings.

(2)Mixed-Bed Deionization Systems

A mixed-bed deionizer (MBDI) consists of two types of ion exchange resins, cationic and anionic, that are mixed together in a single bed. As water passes through the bed, the ions in the water are attracted to the resin and are exchanged for hydrogen or hydroxyl ions. This process removes contaminants such as ions of calcium, magnesium, iron, copper, and other metals, as well as organic ions such as chlorides and sulfates.

MBDIs are commonly used in a variety of applications, including industrial processes, power generation, laboratories, and medical facilities. They are particularly useful for producing high-purity water that is required for certain types of manufacturing and scientific processes.

Figure 4 Mixed-bed deionizer.

Pros of Mixed-Bed Deionization Systems
  • High efficiency: Mixed bed DI systems are highly efficient at removing ions from water. They can produce water with a total dissolved solids (TDS) level of less than 1 ppm, which is much purer than what can be achieved with other types of water treatment systems.
  • Environmentally friendly: Mixed bed DI water systems do not produce any chemical byproducts, making them environmentally friendly.
  • Cost-effective: In the long run, mixed bed DI systems can be cost-effective due to their low maintenance requirements and high efficiency.
  • Compact size: Mixed bed DI systems are relatively small and compact, making them easy to install and maintain.

(3)Electrodeionization Systems

Electrodeionization (EDI) is a water treatment process that uses electricity to remove ions from a solution. It is a continuous process that uses a series of ion exchange membranes and electrodes to separate charged particles from a solution.

A series of electrodes and ion exchange membranes, typically made of carbon or graphite, are used in an EDI system to deionize water. A direct current is used to charge the electrodes, and as a result, the opposing charge on the electrodes attracts the ions in the water.

Electrodeionization Systems

As the ions are attracted to the electrodes, they pass through the ion exchange membranes and are removed from the water. The EDI process is highly efficient and can remove ions to a high degree of purity, making it an ideal method for producing ultrapure water. It is commonly used in the pharmaceutical, electronics, and power generation industries, as well as in the production of drinking water.

Pros of Electrodeionization Systems
  • High-purity water production: EDI systems are capable of producing high-purity water with a resistivity of 18.2 megohms-cm or higher.
  • High flow rates: EDI systems can handle high flow rates, making them suitable for large-scale water treatment applications.
  • Environmental benefits: EDI systems do not generate hazardous waste and do not use chemical additives, making them more environmentally friendly than some other water treatment technologies.
  • Multiple applications: EDI water systems can be used in a variety of industries and applications, including power generation, pharmaceuticals, and electronics manufacturing.


Water deionization systems are a reliable and effective way to purify water by eradicating pollutant ions and impurities. There are several types of deionization systems available, including mixed-bed deionizers, two-bed deionizers, and electrodeionization. Each type has its own unique features and benefits, and it is important to choose the right system for your specific needs. Proper installation and maintenance of a deionization system are crucial to ensure its effectiveness in purifying water.

For A-list deionizers and additional information on deionization technologies and devices, do not hesitate to consult NEWater.

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