Better Brine Purification, Longer Membrane Life: The Hidden Economics of Chlor-Alkali Production

Southeast Asia’s chlor-alkali industry continues to expand.

In Thailand, AGC Vinythai recently completed a major expansion of its Map Ta Phut chlor-alkali plant. The project uses thyssenkrupp nucera’s e-BiTAC v7 ion-exchange membrane electrolyzer technology and adds approximately 220,000 tons per year of caustic soda capacity. The expansion is intended to meet growing demand for caustic soda and PVC across Southeast Asian industries.

For chlor-alkali producers, however, installing a high-efficiency electrolyzer is only one part of the overall production system.

Another critical question lies upstream:

How clean is the brine entering the electrolyzer?

The relationship can be summarized in one chain:

Brine purification → Electrolyzer protection → Membrane life → Operating cost

Why Membrane Electrolyzers Require Higher-Quality Brine

Modern membrane-cell chlor-alkali technology offers significant advantages in energy efficiency and caustic soda quality.

At the same time, ion-exchange membranes impose more stringent requirements on feed-brine quality.

When converting conventional diaphragm-cell plants to membrane-cell technology, thyssenkrupp nucera specifically identifies enhanced brine purification as an important process requirement, because membrane cells require brine with higher purity.

Untreated or primary-treated brine may still contain suspended solids, calcium and magnesium compounds, colloidal matter and other impurities.

Although these impurities may be present at relatively low concentrations compared with the overall salt concentration, their impact on long-term plant stability can be significant.

If contaminants enter the electrolyzer system, they may contribute to deposition, membrane fouling and unstable electrolysis conditions.

Over time, this may lead to:

● Higher operating resistance

● Lower current efficiency

● More frequent maintenance

● Shorter ion-exchange membrane service intervals

● Higher energy or chemical consumption

● Increased unplanned downtime

In other words:

Brine purification is not simply a filtration issue. It is also an electrolyzer-protection issue.

Why This Matters More as Electrolyzer Efficiency Improves

Electrolyzer suppliers continue to reduce power consumption.

For example, thyssenkrupp nucera states that its latest BM and e-BiTAC membrane-cell technologies can achieve specific power consumption below 1,960 kWh per ton of NaOH under specified operating conditions. The company also emphasizes membrane life and lifecycle services as important components of chlor-alkali plant economics.

This creates an important dynamic.

As the electrolyzer itself becomes more efficient, the cost of upstream instability may also become increasingly significant.

If poor feed quality leads to avoidable fouling, cleaning or membrane replacement, even a highly efficient membrane electrolyzer may not be able to deliver its full lifecycle value.

Therefore, the economics of brine purification should not be evaluated solely based on the cost of the filtration equipment itself.

A more important question is:

To what extent can stable brine quality protect the value of the downstream electrolyzer?

Where Ceramic Membranes Can Fit

Chlor-alkali brine is a challenging process stream for filtration.

It is characterized by high salt concentration, alkaline conditions and the presence of fine suspended solids or colloidal impurities.

Jiuwu Hi-Tech has developed ceramic membrane systems for chlor-alkali brine purification under these types of operating conditions.

Cross-flow filtration keeps the brine moving continuously along the membrane surface while retaining fine suspended solids and colloidal particles. Ceramic membrane materials provide the chemical and mechanical stability required for demanding industrial operation.

Jiuwu Hi-Tech’s chlor-alkali brine purification process design focuses on the separation of suspended solids, as well as precipitates and other solid-phase materials formed from calcium- and magnesium-related impurities during upstream treatment. Cross-flow operation is used to help control membrane fouling.

Therefore, the role of ceramic membranes is not to replace every stage of the brine purification process.

Their more important role is to provide a more stable solid-liquid separation barrier between upstream brine treatment and the high-value electrolysis section, helping provide more stable feed conditions for downstream membrane electrolysis.

From Filtration Performance to Operating Economics

For plant managers, purchasing teams and process engineers, ceramic membrane performance should not be evaluated based on a single question such as:

“What is the membrane flux?”

A more comprehensive evaluation should include:

1. Brine quality stability

Can the system consistently control fine suspended solids and colloidal impurities before the brine enters the electrolyzer?

2. Cleaning frequency

How often does the filtration system need to be shut down or chemically cleaned?

3. Electrolyzer protection

Can improved upstream clarification reduce the contaminant load on ion-exchange membranes and electrodes?

4. Membrane replacement

Can more stable feed quality help protect expensive ion-exchange membranes and extend their service intervals?

5. Total operating cost

Over several years of operation, how will costs associated with chemicals, labor, downtime, energy consumption, membrane replacement and other component replacement change?

This is where a filtration project moves beyond a simple equipment procurement decision and becomes a production-economics issue.

A More Valuable Question for Southeast Asian Chlor-Alkali Plants

As new chlor-alkali capacity continues to be added across Southeast Asia, producers in the region are increasingly focused on efficiency, reliability and lifecycle costs.

The question therefore should not simply be:

“Which filtration technology is cheaper?”

It should be:

“Which brine purification strategy can help the electrolyzer operate more reliably throughout its lifecycle?”

For new membrane-cell projects, capacity expansions and diaphragm-to-membrane conversions, brine purification deserves to be evaluated as an integral part of the electrolysis system rather than simply as an isolated upstream filtration step.

Jiuwu Hi-Tech provides ceramic membrane systems, engineering design and pilot-testing services for chlor-alkali brine purification. Project evaluation can begin with brine composition, suspended solids, calcium and magnesium levels, temperature, plant capacity and the feed-water quality required by the downstream electrolyzer, followed by process evaluation and technical validation.