Water treatment is a central component of numerous industrial processes. Depending on the application, certain ions or compounds must be removed from the water in order to adapt the quality of the water to the respective requirements. Three of the most important processes in this context are softening, decarbonization and demineralization. In this article, we explain how these processes work and their advantages, including the role of mixed-bed filters for fine purification.
Table of contents
Softening: removal of water hardness
Water hardness is caused by dissolved calcium and magnesium ions. These ions can lead to limescale deposits in pipes and systems, causing efficiency losses and increased maintenance costs.
Functionality
Softening is achieved through the use of strongly acidic cation exchangers (SAC). These exchange resins contain sulphonic acid groups that bind positively charged ions such as and and exchange them for hydrogen or sodium ions.
Advantages of softening
- Prevention of limescale deposits: Protection of pipes, heat exchangers and boilers.
- Increased energy efficiency: Limescale-free systems ensure optimum heat transfer.
- Cost reduction: Lower maintenance costs and longer service life of the systems.
Decarbonization: Removal of carbonate hardness
Carbonate hardness is caused by dissolved bicarbonate ions, which can react with calcium and magnesium ions to form calcium carbonate (lime), which is poorly soluble. Decarbonization reduces this hardness and lowers the alkalinity of the water.
Functionality
Decarbonization is often carried out with weakly acidic cation exchangers (WAC), which selectively bind cations that are coupled to bicarbonates. This produces carbonic acid, which breaks down into water and CO₂. To remove the CO₂ from the water, a CO₂ trickling filter is often installed downstream.
Advantages of decarbonization
- pH stabilization: Reduction of alkalinity ensures more stable chemical conditions.
- Limescale prevention: Prevents deposits and protects downstream systems.
- More efficient processes: Reduced need for chemicals and improved operating behavior.
Complete demineralization: removal of all dissolved salts
Demineralization is the most comprehensive form of water treatment and aims to remove all dissolved ions from the water. The result is ultra-pure water with minimal conductivity that is suitable for demanding industrial and technical applications.
Functionality
Complete demineralization combines the use of strongly acidic cation exchangers (SAC) and strongly basic anion exchangers (SBA). While the cation exchangers remove all positive ions such as calcium, magnesium and sodium, the anion exchangers eliminate negative ions such as chloride, sulphate and nitrate. For maximum purity, a mixed-bed filter is installed downstream for fine purification.
Photo: Our ALMA ION cation and anion exchangers
Role of the mixed bed filter
A mixed bed filter combines cation and anion exchangers in a single unit. It is used for fine polishing by removing even the smallest residual amounts of ions that have not been completely eliminated by the upstream exchange stages. The result is water with a conductivity of less than 0.1 µS/cm, which is necessary for highly sensitive applications such as in the electronics or pharmaceutical industries.
Advantages of demineralization
- Extremely high water purity: Ideal for sensitive processes that require the highest standards.
- Corrosion protection: Minimal conductivity prevents damage to systems.
- Flexibility: Adaptable to different industrial requirements.
Applications of softening, decarbonization and demineralization
The three processes are used in a variety of industries and applications:
- Softening: Softening plays a key role, particularly in building services and industrial cooling systems. By preventing limescale deposits in heat exchangers, pipes and boilers, energy efficiency is increased and the service life of the systems is extended.
- Decarbonization: It is essential for boiler water treatment to prevent corrosion and limescale formation. In the food industry, decarbonization ensures optimum process water, while in cooling systems it reduces the risk of deposits.
- Demineralization: Demineralization is an indispensable process in the electronics, pharmaceutical and chemical industries. It enables the production of water with extremely low conductivity, which is required for applications such as semiconductor production, sterile injection solutions and steam generation in power plants.
Photo: Our ion exchanger ALMA ION with upstream multi-layer filter ALMA Fil
Summary
The processes of softening, decarbonization and demineralization are essential components of modern water treatment:
- Softening: Prevents limescale deposits and protects systems from wear.
- Decarbonization: Reduces alkalinity, stabilizes the pH value and prevents carbonate hardness.
- Complete demineralization: Removes all dissolved salts and produces high-purity water for demanding applications.
Water quality can be further optimized through the targeted use of mixed-bed filters, which is particularly important in areas such as the electronics, pharmaceutical and power plant industries. Professional planning of these processes not only reduces operating costs, but also significantly increases the efficiency and longevity of systems.
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