Summary
An electro dialysis unit is a water treatment technology that utilizes the selective permeability of ion exchange membranes to selectively direct the migration of ions in water under the influence of a direct current electric field, separating the anions and cations in the solution. Due to its low energy consumption, high water production, high desalination rate, and strong stability, it is used in various fields such as electronics, chemicals, food, hard water softening, and seawater desalination.
Working Principle
The key component of an electro dialysis unit is the ion exchange membrane, which comes in two types: cation exchange membrane (cation membrane) and anion exchange membrane (anion membrane). The cation membrane allows cations in the solution to pass through while blocking anions, while the anion membrane allows anions to pass through and blocks cations. Under the influence of an external electric field, ions in the water move selectively in a directional manner, reducing the number of ions in some parts of the water and increasing them in others, thereby achieving desalination.
Key Technical Parameters
Turbidity < 1 mg/L
Total Iron Content < 0.3 mg/L
Total Manganese Content < 0.1 mg/L
Water temperature: 5-40°C
Chroma < 20℃

Oxygen Demand < 2 mg/L (as oxygen, potassium permanganate method)

Electrodialysis separators utilize the electrodialysis phenomenon to cause ion migration within the compartments of the separator. This leads to the separation of cations and anions in the solution, thereby achieving the purposes of dilution and concentration. Taking sodium chloride as an example, when a water solution containing sodium chloride passes through the compartments of an electrodialysis separator, which are lined with alternating cation and anion exchange membranes and crosswise arranged freshwater and concentrated salt隔plates, ion migration occurs under the influence of a direct current field. Chloride ions migrate towards the anode, while sodium ions migrate towards the cathode, as shown in the figure. Since the exchange membranes have selective permeability, the anion exchange membrane only allows anions to pass through, and the cation exchange membrane only allows cations to pass through. Consequently, cations in the dilution compartment migrate towards the cathode, permeating the cation membrane into the concentrated compartment, while anions in the dilution compartment migrate towards the anode, permeating the anion membrane into the concentrated compartment. In the concentrated compartment, cations and anions also migrate towards the cathode and anode, respectively, under the influence of the direct current field. However, blocked by the exchange membranes on both sides of the compartment, they remain in the concentrated compartment, causing the concentration to gradually increase in the concentrated compartment and the salt content to decrease in the dilution compartment. The electrodialysis separator consists of alternating layers of concentrated and dilution compartments. Half of the compartments are dilution compartments, and the other half are concentrated compartments. Water flows from each compartment are collected through specially designed channels at the edges of the隔plates to form systems of concentrated and dilute water, thus achieving desalination.
Electro dialysis (ED) unit composition
Electrodialysis equipment consists of a power supply converting AC to DC, an electrodialyzer, cleaning units, and more. The main components of the electrodialyzer include an anion exchange membrane (abbreviated as 'anion membrane'), a cation exchange membrane (abbreviated as 'cation membrane'), diaphragms, electrodes, and clamping devices. The compartments formed by the diaphragms serve as channels for the liquid flow. By alternating the anion membrane, cation membrane, and brine/freshwater diaphragms, adding a pair of electrodes, and then clamping them together, an electrodialyzer is formed.

The electro-osmotic membrane separator driven by an electric pump should operate normally under the following feed water quality conditions:
Water Temperature: 5-40℃
b. Manganese Dioxide Index <3 mg/L
c. Free Chlorine < 0.2 mg/L
d. Iron < 0.3 mg/L
e. Manganese                       <0.1 mg/L
f. Turbidity  1.5mm to 2.0mm divider <3 degrees
0.5mm to 0.9mm spacers    <1 degree