EDM | Electrodialysis Metathesis | Innoflow Technologies

Operating Principle

EDM is an ion-exchange membrane process that electrically separates the cations and anions of two different salts and recombines them into new salts.

A typical EDM stack uses cation-exchange membranes (CEMs) and anion-exchange membranes (AEMs) to form a repeating four-compartment structure with two feed channels and two product channels.

Under a DC electric field, cations and anions from each feed solution selectively pass through ion-exchange membranes and combine with different ions in adjacent product channels to form new salts.
In generalized form, the ion combinations of two salts can be changed according to MX + NY → MY + NX.

For example, sodium sulfate (Na₂SO₄) and potassium chloride (KCl) can be converted into potassium sulfate (K₂SO₄) and sodium chloride (NaCl), depending on operating conditions.

Beyond desalination and concentration, EDM enables targeted changes in salt composition while concentrating the products.

EDM Advantages

Salt Composition Conversion

Produces new salts by recombining cations and anions from different salts.

Simultaneous Conversion and Concentration

Ion-exchange reactions and product concentration occur in a single membrane process.

Managing Low-Solubility Salts

Suitable substitution salts can convert sparingly soluble salts into more soluble forms, helping reduce scaling risk during subsequent concentration.

Targeted Product Composition

Feed salts, substitution salts and membrane arrangements can be selected to achieve the desired product salt composition.

Adding Value to Waste Salts

Converts salts in industrial by-products and high-salinity wastewater into useful salt products or process feedstocks.

Applications

Waste & By-Product Salt Conversion

Conversion of Na₂SO₄ and other industrial by-product salts into useful salts
Conversion between chloride, sulfate and other salt compositions
Separation, conversion and recovery of salts from high-salinity wastewater

Value-Added Salt Production

Production of chloride-free fertilizer salts such as K₂SO₄
Production of high-purity inorganic salts
Salt production for chemical and materials industries
Conversion of organic and inorganic salt compositions

High-Salinity Wastewater & ZLD

Control of scaling-forming ion compositions in high-salinity wastewater
Conversion of sparingly soluble salts into more soluble salts
Optimization of salt composition before evaporation and crystallization
Brine resource recovery and integration with zero liquid discharge processes