Back

Why Electrodialysis Efficiency Declines Over Time

Understanding and Solving Performance Issues: Scaling, Fouling, and Aging. Electrodialysis (ED) is a powerful membrane separation process — but like all technologies, it relies on components that degrade over time. If you're seeing reduced ion removal, longer cleaning cycles, or rising energy bills, you're not alone. Many operators face the same challenge: performance losses caused by membrane deterioration. The good news? These issues are predictable, diagnosable, and often preventable. Let’s take a deeper look at the three most common culprits — scaling, fouling, and membrane aging — and what you can do to restore your ED system’s full efficiency.

RALEX® AM8HD Membrane – Advanced Performance & Stability

Popisek

A typical ED stack contains dozens of membranes, flow spacers, gaskets, and electrodes — all operating under electric current and fluid pressure, often 24/7. Over time, even under normal conditions, these components undergo physical and chemical changes that affect performance.

Common warning signs include:

Lower ion removal rates (e.g. conductivity reduction)
Irregular or unstable flow behavior
Higher power consumption
More frequent or prolonged clean-in-place (CIP) operations

Left unaddressed, these problems can lead to increased costs, product yield losses, or even premature system failure.

Three Key Problems: Scaling, Fouling, and Aging

1. Scaling

Scaling occurs when minerals (especially calcium and magnesium salts) precipitate and form deposits on the membrane surface. This is common in hard water environments, or in food & beverage streams where high salt content is typical.

Scaling consequences:

Higher electrical resistance
Blocked ion transport
Decreased recovery efficiency
Difficult and sometimes incomplete chemical cleaning

2. Fouling

Fouling involves the accumulation of organic matter — such as sugars, proteins, fats, or microorganisms — on the membrane or spacer surface. This is most prevalent in complex feed streams like whey, fermentation broth, or fruit concentrates.

Biofouling can develop even with regular cleaning if process conditions aren't optimal.

Fouling impacts include:

Reduced membrane selectivity
Increased pressure drop and energy use
More frequent cleaning and higher CIP chemical costs

3. Membrane Aging

Unlike scaling and fouling, aging is a slow, irreversible decline in membrane functionality. It results from chemical exposure (cleaners, oxidants), mechanical wear, and prolonged electrical load.

Aged membranes don’t always fail suddenly — but they stop delivering the performance you need.

Membrane aging symptoms:

Decreased ion-exchange capacity
Lower current efficiency
Shorter production cycles before cleaning
Gradual loss of process reliability

What Can You Do About It?

There’s no one-size-fits-all fix, but when preventive measures are no longer effective, it's time to consider targeted upgrades.

Your options include:

Replacing individual membranes in affected areas
Retrofitting a module with updated membrane types or designs
Upgrading the entire stack for long-term gains in efficiency and reliability

Proactive replacement may seem like an expense — but it often pays off through lower cleaning costs, reduced downtime, and recovered product quality.

Why RALEX® Membranes Perform Better, Longer

MEGA’s proprietary RALEX® membranes are engineered for durability — especially in harsh or high-fouling applications. These heterogeneous ion-exchange membranes offer improved surface properties and internal structure that resist mineral scaling and organic fouling.

Key advantages:

Smoother surface to limit deposit adhesion
Extended cleaning intervals
High chemical and mechanical stability
Proven long-term performance in dairy, juice, and ZLD systems
Compatible with most existing ED stack brands

Restore, Don’t Replace — Unless It Pays Off

If your ED system shows signs of underperformance, you don’t have to replace it entirely. A smart combination of diagnostics, targeted replacement, and proper membrane selection can breathe new life into your process.

In one juice concentration facility, switching to RALEX membranes reduced CIP frequency by 40% over 12 months.