Membrane systems and ion exchangers


With our comprehensive range of GEMÜ products, we meet the demands of applications such as sea water desalination and water treatment of WFI (water for injection).

The pressure range used for membrane filtration or ultra-filtration is between 0.2 and 6 bar. For nano-filtration or reverse osmosis, the operating pressure can be up to 80 bar depending on the salt concentration. The size of membrane systems varies from small systems, for example a water supply for few consumers, right up to large industrial parks for the treatment of industrial water or larger water supplies for thousands of people.

Water is precious – and we supply the technology to handle it sustainably.

Subdivision between the major areas of application: Process water, ultra pure water and industrial water treatment for reusing water.

The purification of process water and waste water is a high priority in production processes, since almost nothing is made without water. Reusing water plays an ever-more important role in the current climate and requires various valves and components to ensure the optimal treatment of the water for reuse.

➥ Ion exchange for the treatment of process water (e.g. boiler feed water)

For boiler feed water, it is important to have a lower level of dissolved salts such as lime, NaCl, etc. To produce boiler feed water, the water is first pre-filtered. Depending on the source, this may require a simple bag filter or an elaborate multi-layer filter. Then, reverse osmosis removes the majority of the dissolved salts. For fresh water the pressure for reverse osmosis is usually < 20 bar. Ball valves and butterfly valves are frequently used. Stainless-steel globe valves can be used for pressure regulation. 

The subsequent ion exchanger is usually designed as a mixed-bed exchanger. However, it is also possible to construct cation exchangers and anion exchangers separately. The remaining dissolved salts are absorbed into the ion exchanger and regularly regenerated.  Diluted acids such as hydrochloric acid and sulphuric acid are used for regeneration in cation exchangers. Anion exchangers usually use sodium hydroxide for regeneration. 


GEMÜ products: 

Ion exchanger = diaphragm valves or butterfly valves, EPDM or PTFE gasket, PVC body, PP or coatings made from hard rubber, Halar or PFA are also possible. 

➥ Pre-treatment for reverse osmosis in sea water desalination

Modern sea water desalination plants work with multiple process steps. The first step is sieving out large particles. The second filtration stage also removes fine particulate and organic matter such as algae. The actual desalination takes place in high-pressure reverse osmosis systems. The ultra-filtration stage is usually carried out at a low pressure under 6 bar. One special feature is the frequent backwashing processes to avoid blockages in the diaphragms. The UF diaphragms are also regularly cleaned using diluted chemicals. Acids such as citric acid, hydrochloric acid or sulphuric acid eliminate any inorganic contaminants. Organic impurities are eliminated using alkalis. This frequently takes place in combination with disinfection using a sodium hypochloride solution.


GEMÜ products:

Ultra-filtration = butterfly valves with discs coated with Rilsan or Halar, gasket is usually EPDM

Chemical dosing = solenoid valves or diaphragm valves

Valve design overview

Product examples for the areas of application

GEMÜ 48x series butterfly valves made of metal

Various material combinations mean the GEMÜ butterfly valves are suitable for many water applications. The GEMÜ modular system enables many possible combinations of disc, liner and body or actuator. Across all nominal sizes, the butterfly valves offer an impressively short length and high flow rates. Various manual, pneumatic or motorized versions are available for all GEMÜ butterfly valves.



Metal and plastic diaphragm valves

One of the major advantages of diaphragm valves is, among other things, that only two components come into contact with the working medium – the shut-off diaphragm and the valve body, which can be made from metal or plastic. The diaphragm provides hermetic separation between the process medium and all moving parts.


GEMÜ 620

Plastic or metal ball valves

GEMÜ ball valves can be used in many different applications. However, they are primarily used in industrial processes, in the fields of water supply and water treatment.


GEMÜ 710
GEMÜ 717

Solenoid valves

Solenoid valves are designed for fast cycle duties and are particularly suitable for dosing applications. The solenoid valves are frequently used for water treatment.



Find more products on our product pages.


Measurement and control systems

Modular and customized M-block solutions

Add-on components and accessories

We also have many approvals in the water sector. Here is a brief overview: Downloads Ultra-filtration application Information flyer on membrane filtration and ion exchange Whitepaper on intelligent control in membrane filtration Get in touch with us.


Ultra-filtration application

pdf453 KB

Information flyer on membrane filtration and ion exchange

pdf1.59 MB

Whitepaper on intelligent control in membrane filtration

pdf315 KB

Get in touch with us.

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