Pilot Plant Test of Single-Pass Electrodialysis Reversal System

Area of Science:

• Water treatment technologies
• Chemical engineering
• Environmental science

Background:

• Electrodialysis (ED) is a key technology for water desalination.
• Optimizing ED performance, particularly recovery and cost-efficiency, remains an active research area.
• Controlling operational parameters is crucial for mitigating membrane damage and ensuring process stability.

Purpose of the Study:

• To investigate single-pass electrodialysis desalination with optimized flow velocities and pressure control.
• To evaluate the performance of a custom-designed electrodialyzer in demineralizing river water.
• To assess the economic viability and deep demineralization capabilities of the developed ED system.

Main Methods:

• Utilized single-pass electrodialysis (ED) operation with varied linear flow velocities in diluate and concentrate compartments.
• Implemented pressure difference control between compartments to minimize leakage and membrane damage.
• Tested under- and overlimiting current density regimes and long electrode polarity reversal cycles in a pilot plant.
• Analyzed water conductivity, recovery rates, and desalination degrees.

Main Results:

• Achieved 70-75% recovery and 75-96% desalination degree for river water with initial conductivity around 500 µS/cm.
• Demonstrated a 52% reduction in unit cost compared to commercial solutions at a diluate conductivity of 74.3 µS/cm.
• Experimentally confirmed deep demineralization down to 17.9 µS/cm (single-stage ED) and 8.52 µS/cm (two-stage ED).

Conclusions:

• Single-pass electrodialysis with controlled pressure offers an efficient and cost-effective method for water desalination.
• The developed ED system shows promise for both initial demineralization and deep demineralization applications.
• Optimized operational strategies in ED can lead to significant improvements in recovery and economic benefits.