The Principle of Electrodeionization (EDI)

The industrial world is now growing and increasingly demanding increasingly stringent specifications from various sides. One side that is quite strict is in the field of utilities, especially water. Some industries such as pharmaceuticals, instrumentation as well as the manufacture of special inks actually need water with very special specifications.

This base specification is called the Ultra Pure Water Specification. Which can only be obtained from a high-level purification process, one of which is the EDI process. And in this article we will write how the EDI process is so that it can produce water with high purity or Ultra Pure Water?

Principles for Using EDI

The process of purifying water to the level of ultra pure water, is actually already commonly done in the pharmaceutical industry and also instrumentation. The process of getting ultra pure water is usually done with the Mixbed Demin system.


This Mixbed Demin system, used to be the main one used to obtain Ultra Pure Water before the EDI process was discovered. The process is the absorption of cations and anions in the water with resin in the tank. The process of absorption of cations and anions in this water, must go through a resin regeneration process which is quite troublesome and requires a lot of good costs.

The working principle of EDI, has a difference with the work principle of Mixbed Demin. Where this cation and anion will be given a reaction via a DC electric current. So finally it can separate itself from the permeate water to the concentrate water. This gives advantages to the EDI process, because there is no need for a regeneration process like the Mixbed Demin process.

Advantages of using EDI


After learning about the working principles of the EDI Process, we will discuss a little about what are the advantages of the EDI (Electrodeionization) process.

Does not require regeneration

The process of water purification using EDI, does not require a regeneration process. This is because the working principle of EDI itself is not an Ion exchange. But rather to the injection of the electron charge in the impurities present in the water. Its function is to be able to easily make the impurity move into the cation or anion chamber in the EDI System.

In the absence of the regeneration process, it certainly makes operational costs reduced, accompanied by reduced operational processes as well as troublesome installations.

Tidak menghasilkan Limbah 

 Proses penyerapan cation dan anion dengan meggunakan mixbed, akan membutuhkan proses regenerasi agar si mixbed dapat digunakan terus menerus. Proses regenerasi itu sendiri tentu kita tahu, bahwa dia memerlukan Asam HCl dan juga basa NaOH. Yang akhirnya nanti akan menghasilkan limbah regenerasi yang memiliki pH dan TDS diluar batas yang bisa diterima baku mutu. 

This regeneration waste must be treated later in the wastewater treatment process (WWTP / WWTP) and this is certainly an additional cost that must be taken into account. Because Demin owners must incur investment and operational costs to be able to process it.

Unlike the process at EDI, where there is no need to regenerate so the owner does not need to bother thinking about the costs for WWTP investments and operations.

A Simplified Operating System


The absence of the regeneration process, certainly will reduce the valve that must be operated. This will facilitate the operational process as well as the operational process between RO and Demin.

A simpler operational system will have an impact on reducing the number of operators needed to run the system. And this will also have an impact on the more stable discharge generated because the maintenance and regeneration processes will also be greatly reduced.

 Low Power Consumption


Although in principle EDI functions using DC electric current. But the reality on the ground if we calculate the reduced pumping, regeneration, maintenance and so on, then of course in terms of power consumption is much lower than the Mixbed or demin process that is replaced.

Smaller System Area

The last advantage of choosing EDI as a process for obtaining ultrapure water is that EDI only requires a much smaller area. That is, only 30% of the area required by the Mixbed system.

This smaller area is obtained because the EDI process has eliminated regeneration, re-washing, rinsing, and other treatment processes. As a result, the EDI system area itself becomes smaller. The advantage of this area is certainly very desirable by owners who have limited area in the factory.