Water Treatment

We are facing water shortages due to worldwide trends of increasing population and climate change. Many regions of the world lack sufficient water resources.

The fact that there is not enough fresh water to support our growing population forces us to look into alternative water sources and economic purification methods for today’s and tomorrow’s water consumption needs.

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Where surface or other fresh water is available, Liqui-Flux® ultrafiltration modules can be installed to remove turbidity, suspended solids and pathogens in order for that water to be used safely.

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They can also improve the effluent quality of waste water to a level that allows its reuse in various applications. Additionally, Liqui-Flux ultrafiltration modules serve as perfect pre-treatment step for enhancing the performance of reverse osmosis membranes in desalination systems.

Liqui-Flux modules have demonstrated reliable operation and sustained membrane integrity in various applications. Some of those include:

Pre-treatment to Reverse Osmosis

Over the last 30 years the relevance of reverse osmosis (RO) has gained great significance in all applications where salt content has to be removed to support higher energy efficiency compared to traditional procedures (e.g. thermal methods).

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To avoid severe fouling of the spiral wound RO membrane modules and to prevent an irreversible pressure increase, RO membrane modules require an effective pre-treatment to keep the driving pressure low, to have less frequent cleaning cycles and fewer shut down times.

Liqui-Flux® ultrafiltration modules exhibit superior performance when compared to conventional treatment steps, such as flocculation, sedimentation and sand filtration. Investigations have shown that particle sizes below 1μm may have a negative impact on the fouling on the RO membranes. In contrast to conventional treatment methods, these small particles can be filtered out by Ultrafiltration (UF).

UF provides an excellent filtrate quality, not influenced by varying raw water qualities whereas conventional treatment steps are limited particularly in peak load situations. Furthermore, Liqui-Flux ultrafiltration pre-treatment reduces the amount of sludge for disposal and does not require frequent replacement of depth filter cartridges.

Thus application of Liqui-Flux RO pre-treatment of feed water is very recommendable and may significantly lower the operating cost of Reverse-Osmosis plants.

Waste Water Reuse

An area of major importance for Liqui-Flux® ultrafiltration is the tertiary water treatment that comes after the mechanical and biological cleaning steps of a conventional waste water treatment plant.

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Improved water quality for re-use or safe discharge

Liqui-Flux Ultrafiltration (UF) Modules could significantly improve the effluent water quality by effectively removing bacteria and particulate organic matter such as biomass. This reduces the remaining content of organic Phosphate, Nitrogen and Carbon as well as effectively removing bacteria that would otherwise discharge into fresh water reservoirs used for swimming and bathing. In many applications UF filtrates are used for direct irrigation or industrial purposes such as process water and cooling water.

Compared with membrane bioreactors (MBR), which can obtain comparable effluent qualities, UF has several engineering and operating advantages. Some of those are:

  • Water treatment plants can be upgraded with Liqui-Flux modules without any modifications to existing equipment.
  • Depending on the required volume flow, Liqui-Flux ultrafiltration can be designed and installed to treat only a partial stream.
  • In waste water re-use situations, Liqui-Flux ultrafiltration modules will operate at significantly higher flux rates compared to MBR installations. This will reduce the required membrane area and therefore lead to lower captial expenditures.
  • Pressure driven ultrafiltration modules require less energy for filtration and cleaning resulting in reduced operating costs.
  • Contaminated water flows only inside the capillary membrane lumen ensuring clean and hygienic working area even in case of maintenance work.

Drinking Water

As part of the public water supply, Liqui-Flux® modules are efficient filtration devices for all water resources exposed to the surface. These may include rivers, lakes, reservoir water and spring water in karst areas.

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Safe drinking water

All these resources may contain pathogens, which cannot be sufficiently deactivated by usual disinfection such as chlorination. Of particular importance are protozoae such as Giardia and Cryptosporidia, which bear a high risk of infection even at low concentrations.

Liqui-Flux ultrafiltration modules provide a safe barrier to these pathogens.

Conventional treatment, such as flocculation over multilayer filters requires a time-critical adaptation of flows along frequently measured laboratory parameters such as in the event of varying raw water qualities due to heavy rainfall.

Liqui-Flux ultrafiltration modules can be operated safely and automatically, without an additional operator and expensive laboratory monitoring because the filtrate quality is not heavily influenced by varying raw water inlet parameters.

In combination with in-line coagulation, Liqui-Flux ultrafiltration modules can also be even more efficient for the removal of arsenic compounds and color (humic substances) from ground or deep well water.

In many regions of the world the only access to safe drinking water is with bottled water. Automated Liqui-Flux ultrafiltration systems are an economic alternative in the final disinfection step and can replace commonly used single-use cartridge filters.

Swimming Pools

Chlorination of swimming pool water is the most common method used to maintain hygienic conditions. Unfortunately this treatment leads to volatile byproducts most well known by their characteristic smell. The Chloramines or Trihalomethane byproducts may irritate the respiratory tract and it is a constant goal to keep chlorine dosage quantities as low as possible.

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A smarter solution

By using Liqui-Flux® ultrafiltration modules it is possible to significantly reduce the amount of disinfection chemicals required to maintain a healthy and pleasant environment in spas and swimming pools.

Ultrafiltration systems also require a very small foot-print, which is important in basements of existing swimming pools where space is often limited.

For highly contaminated pool circuits such as in large water parks, ultrafiltration can be installed with minimal to no additional construction effort at varying load conditions.

Process Water

Many production facilities require high quality water for their processes. Depending on the specific industrial process these requirements can be even more stringent than for potable water.

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Reduced consumption and lower sewage costs

Depending on the individual case it can be very cost efficient to re-use Liqui-Flux® ultrafiltration-treated water from existing processes instead of costly fresh water thus reducing water consumption and lowering sewage costs at the same time.

3M can provide testing equipment and sophisticated laboratory services to run on- or off-site trials to support your decision making process.

Low energy consumption, little maintenance, and easy operation makes ultrafiltration with Liqui-Flux modules an economic investment towards an environmentally friendly operation with a small carbon footprint.