What Is Electrodeionization and How Does It Work?

January 13, 2022 - Nathan Olszak
What Is Electrodeionization and How Does It Work?

One type of water treatment is electrodeionization (EDI), which uses ion exchange membranes, direct current electricity and ion exchange resin to effectively deionize water. The resulting water is suitable for a wide range of applications across many different industries. An electrodeionization unit can meet high purity standards and maintain effective operation with little intervention. Learn more about electrodeionization — what it accomplishes, how it works and what applications it serves.

Table of Contents

What Does Electrodeionization Remove From Water?

Electrodeionization can remove salts and ionizable aqueous contaminants, including ammonia, carbon dioxide, boron and silica. High purity water is necessary across many industries, such as pharmaceuticals, electronics and laboratories. For these applications and others, water ions are removed in a process called deionization.

An ion is any molecule with a net electric charge that’s either positive or negative. Common examples of ions include sodium, calcium, chloride and potassium. Deionization makes water pure, removing these molecules. Once these molecules are gone, the water is safe for tasks like mixing in medications or using in controlled laboratory settings.

Deionization vs. Electrodeionization — What's the Difference?

Electrodeionization is a form of deionization that uses electricity to remove the ions from the water. EDI is a chemical-free operation, consumes only electricity and achieves very high purity rates, making it a preferred method in many settings. Other forms of deionization use methods other than electricity to remove ions.

Ion Exchange and Electrodeionization

The electrodeionization working principle is ion exchange. Ion exchange involves swapping undesired ions for different ones with the same charge. In water purification, the ions are exchanged for hydrogen and hydroxyl.

The resin beads within the system achieve ion exchange. Conventional ion exchange technology, not involving electricity, relies on the polymer resin beads to attract unwanted ions. The ions buildup on the resin beads, and the beads grow saturated with contaminants over time. Once saturated, the beads require replacement.

Electrodeionization, on the other hand, uses electricity to create a continuous flow of ions out of the system. The resins that achieve the ion exchange continually regenerate, so the contaminants never saturate or exhaust the system.

Advantages and Disadvantages of Electrodeionization

Advantages and Disadvantages of Electrodeionization

Industrial electrodeionization has its pros and cons when compared to other water purifying methods. When searching for the right water treatment technology for your application, consider each method’s benefits and drawbacks.

Benefits of Electrodeionization

Here are some of the main benefits of electrodeionization chemical cleaning:

  1. No contaminant buildup: EDI’s ion-exchange beds are continuously regenerated, meaning they will not exhaust the same as ion-exchange beds operated in batch mode. As the concentrates remove impurities, they will not build up, accumulate or exhaust the resin.
  2. Chemical-free: No chemicals are necessary for electrodeionization, making it a clean, safe and environmentally friendly method.
  3. Ion-free result: The process is effective. It removes virtually all ions within the water. This makes the water safe for high-stakes applications, like pharmaceutical creation.
  4. Recyclability: Another key benefit of electrodeionization is that the collected ions are available for recycling or repurposing.

Drawbacks of Electrodeionization

While electrodeionization offers key benefits, it also has its drawbacks. Some disadvantages of the technology include:

  1. Only removes ions: The main shortcoming of electrodeionization is that it only removes ions from the water. The water must undergo other purifying processes, like reverse osmosis, to remove other contaminants.
  2. Membrane replacement costs: To maintain an effective system, the membranes through which the exchanged ions travel will need occasional replacement, which can be expensive.
  3. Consumes electricity: If you’re looking to reduce electricity expenses, electrodeionization may not be the best choice, as it consumes a continuous stream of electricity.
  4. Performance may vary: An electrodeionization system’s performance might vary based on the feed water composition.

What Is Electrodeionization Used For?

The process of electrodeionization produces deionized water, which is useful in many different applications and industries. Some of the industries that need pure, deionized water include:

  • Electronics: When you drop your phone into a sink or a puddle, it’s not the water itself that causes damage but the ions within the water. Ion-free water will not damage electrical components, so it’s helpful for electrical manufacturing purposes.
  • Laboratory testing facilities: Deionized water allows for accurate, controlled experiments since unpredictable ion content could cause variations.
  • Manufacturing: Many different manufacturers need deionized water for various processes.
  • Pharmaceuticals: The ions within impure water might damage or alter medicines, which can cause a health hazard. For that reason, pharmaceutical companies need deionized water.
  • Power generation and cooling: Power plants require deionized water for their boilers or turbine combustors. Cooling towers need deionized water to avoid corrosion or scale buildup.
  • Food manufacturing: Similar to pharmaceuticals, food manufacturing calls for purified water to prevent possible health issues.
  • Chemical manufacture: Chemical manufacture is a complicated process — the ions in impure water could disrupt it or even make it impossible.

Choosing the Right Electrodeionization System for Your Application

When choosing an electrodeionization system, you’ll need to consider several relevant factors. An EDI module enhances the filtration process and is typically implemented following a reverse osmosis system. The cleaner the water can be when reaching the EDI module, the longer the system’s lifespan you can expect. Here are some things to think about to help you make accurate comparisons:

  1. Flow rates: Some systems can handle greater flow rates than others. The system will have a maximum flow rate beyond which performance will decline.
  2. Feed water: You should also think about the feed water that will enter the electrodeionization system. Depending on the contaminants present in your feed water, you may need to use multiple purification techniques.
  3. Requirements: Make sure the electrodeionization system you choose meets your industry’s standards and requirements, removing the necessary percentage of ions.
  4. Customization: Consider ways you may want to customize your electrodeionization system. For instance, you may prefer a specific brand for components.
  5. Controls: Think about how the system operates and the level of automation. If it has manual controls, you’ll need to invest resources into operator training. Electrodeionization troubleshooting can be complicated.

Learn More About Electrodeionization With Complete Water Solutions

Learn More About Electrodeionization With Complete Water Solutions

Electrodeionization is an effective technological solution for removing unwanted ions from your water supply. It produces reliably purified water, useful in a wide range of applications across many industries. When paired with another type of water treatment, like reverse osmosis, the resulting water is as pure as possible.

Learn more about electrodeionization, along with other water purification techniques, with Complete Water Solutions. We have the expertise to know what systems will work best for your application. We offer a variety of brands and options for new or updated water treatment systems. To find out more, contact us at Complete Water Solutions.

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