EDI (Electrodeionization) is a revolutionary water treatment technology; it is a membrane separation desalination technology that skillfully combined the electrodialysis technology and ion exchange technology together, which is high-tech, green and environmental protection technology.

 EDI equipment uses the RO outlet water as feed water. The resistivity of RO outlet water is normally 40-2μS/cm（25℃), the resistivity of EDI outlet water can reach 18MΩ.cm (25℃) normally. According to the application of deionization water and the setup of the system, EDI outlet water can meet the requirements of resistivity 1-18.2MΩ.cm (25℃).

 The advantages of EDI equipment are continual water production, no acid and alkali regeneration, unattended operation etc. It has been replacing the mix bed as the fine treatment equipment gradually. Due to its higher environmental protection character, easy in operation, EDI has been accepted by more and more people and used in pharmaceutical, electronic, electricity, and chemical industry widely. Its appearance is a revolutionary progress of water treatment, which marked the water treatment industry finally entered into green industry.

 Advantages of EDI

EDI utilizes chemical-free regeneration.  This means a safer workplace because there is no need to store or handle hazardous acid and caustic.  There are fewer regulation concerns due to the absence of these corrosive chemicals and there is no waste neutralization or disposal issues.

EDI is a continuous process.  The ion exchange resins are being continuously being regenerated by the DC electric field.  There is no “breakthrough" of ions as happens in conventional ion exchange operations, therefore the quality of the water remains at a constant high level of purity.  The electric field also provides a bacteriostatic environment inside of the EDI cell, inhibiting the growth of bacteria and other organisms.

EDI has significantly lower operating costs than conventional ion exchange processes.  Only a relatively small amount of electric power is needed to provide high purity water.  The lack of acid and caustic regeneration means less operator attention and lower labor costs.  Capital costs can also expected to be lower, especially because no chemical storage, pumping and neutralization equipment is required.

EDI has a significantly smaller footprint than conventional ion exchange processes.  This means less plant space will be required to provide the same quantity of water.

 When to Consider Using EDI

EDI may be considered to be a competitive alternate process to:

Regenerable Mixed Bed Deionization

No acid or caustic bulk storage, pumping, waste neutralization or disposal issues.  Lower operating cost due lower manpower requirements as well as the lack of chemical regeneration.  Smaller footprint.

Service Mixed Bed Deionization (off-site regenerated rental vessels)

No ionic breakthrough resulting in a constant high quality of water.  No rental vessels, associated freight or monthly demurrage charges.

Second pass of RO

Eliminates the need for a second bank of RO membranes and associated plumbing, pumping and control equipment.

 Typical applications for EDI

Providing USP (United States Pharmacopeia) grade water

Purified Water

Feed to WFI (Water For Injection) stills

Steam Generation / Boiler Feed

Microelectronics / Semiconductor makeup and rinsewaters

For high quality makeup demineralized water

General Industry

Surface finishing

Chemical manufacturing