Electrodialysis

Electrodialysis water treatment

Join our quick introduction to the electrodialysis process in wastewater treatment hosted by Tomas Dornik. Find out what the difference is between feed and bleed process and batch mode processing, RALEX® electrodialysis membranes, etc.

Watch the webinar recording on our MEGA YouTube channel.

Advantages of MEGA ED in water treatment

• High water recovery up to 95 %.
• High concentration of brine TDS up to 200 g/l.
• Less susceptibility to organic fouling.
• Strong chemicals for cleaning (acid + caustic).
• Tolerance to free residual chlorine.
• Silica does not affect water recovery.
• 10+ years of membrane lifetime.
• Robust solution.

MEGA electrodialysis applications in water treatment

With water pollution becoming an increasingly serious problem worldwide, electrodialysis in water treatment is mostly used for:

• Zero Liquid Discharge.
• Treatment of wastewater from pulp and paper mills.
• Desalination of high-silica water.
• RO brine treatment.
• Condensate treatment from fertilizer production (NPK, NH₄NO₃).
• Textile wastewater treatment.
• Cooling tower blowdown treatment.

What is electrodialysis reversal?

The electrodialysis reversal (EDR) is a continuous self-cleaning electrodialysis process using a periodic reversal of the DC polarity and switching of concentrating and diluting flow streams.

Thanks to the self-cleaning process the membranes have a much longer lifetime in the EDR stacks.

What is bipolar membrane electrodialysis?

The electrodialysis bipolar membrane process (EDBM) is based on the unique property of bipolar membrane (BM) - electro-dissociation of water. BM effectively divides water into H+ and OH− under the influence of the applied electric field.

MEGA bipolar electrodialysis stack consists of bipolar and monopolar (cation/anion-exchange) membranes, which convert waste salts into acids and bases.

This process is kown as a Non-thermal ZLD process.

Electrodialysis bipolar membranes for industrial use by MEGA

The non-thermal ZLD process is used for the recovery of acid and caustic from waste salts for local use. It is an environmentally friendly technology that reduces operating costs for the wastewater treatment plant.

• High limits of feed water hardness.
• Increased mechanical stability.
• Long lifetime.
• Low-maintenance modules.
• Elimination of thermal treatment.
• Reduction of wastewater.
• Production of acid/caustic for reuse.
• Unique low-cost membranes.

ED is an electrically driven method of removing dissolved ionic compounds

ED is suitable technology for the following cases:

• Treatment of water with a higher tendency to fouling or variable quality of feed.
• High recovery is required.
• High concentration of concentrate is required (up to 200 g/l).
• High silica waters.
• Suitable for existing plants without need of external pre-treatment.

RO is a pressure-driven method for removing dissolved solids

RO is suitable technology for the following cases:

• Treatment of water with a low tendency to fouling and constant quality of feed.
• High recovery not strictly required.
• High concentration is not strictly required.
• High rejection required, i.e. a high degree of desalination.

The main benefits of ED

• Higher resistivity against organic fouling.
• Tolerance of EDR membranes to chlorine.
• Resistivity against the risk of scaling.
• Silica does not affect EDR performance.