Water filter and method for protecting a water filter from germ formation

Abstract

The disclosure relates to a water filter comprising a filter membrane and an alkalizing material. The alkalizing material is formed as a sintered material, in particular as a granulate containing a hydroxide.

Description

Field of invention

[0001] The invention relates to a water filter. The invention further relates to a method for protecting a water filter from bacterial growth. The invention relates in particular to water filters designed for the treatment of drinking water. Background of the invention

[0002] Disclosure WO 2022 / 101084 A1 (BWT Holding GmbH) shows a water filter which is equipped with an alkalizing material, in particular a carbonate, to prevent germ formation.

[0003] The alkalizing material increases the pH value in the filter, at least during stagnation phases (i.e., when no water is being drawn), to such an extent that bacterial growth is at least reduced.

[0004] The difficulty lies in providing a material that maintains such an alkalizing effect over a long period of time. Object of the invention

[0005] The invention, in contrast to the aforementioned prior art, is based on the objective of providing a water filter with germ protection which, in an improved manner, also reduces bacterial growth over a longer period of time. Summary of the invention

[0006] The object of the invention is already achieved by a water filter and by a method for protecting a water filter from germ formation according to one of the independent claims.

[0007] Preferred embodiments and further developments of the invention can be found in the subject matter of the dependent claims, the description and the drawings.

[0008] The invention relates to a water filter. The water filter comprises a filtration membrane.

[0009] The filtration membrane can be designed in particular as a microfilter or ultrafilter.

[0010] In particular, it can be a membrane package with a hollow fiber membrane. Such membrane packages can especially include membranes that are folded on one side and bonded on the other side using a potting compound.

[0011] Depending on the flow direction, the water to be treated enters the individual membranes from the outside and exits the membrane through its open side, which is embedded in the potting compound. Operation in the reverse direction is also possible.

[0012] Microfilters typically have a pore size between 0.1 and 1 µm and can already filter out a large proportion of bacteria. Ultrafilters typically have a pore size of less than 0.1 µm and can remove both viruses and bacteria.

[0013] With this type of filter membrane, increased bacterial and biofilm growth can occur on the concentrate side. Microorganisms accumulate on the membrane and become embedded in a matrix of extracellular polymeric substances.

[0014] The resulting biofilm reduces the membrane's filtration efficiency. Furthermore, it can lead to back-contamination of the concentrate into the pipe network.

[0015] According to the invention, the water filter comprises an alkalizing material, which is formed as a sintered material with a hydroxide. In particular, the material is formed as granules.

[0016] It has been found that sintered hydroxide retains an alkalizing effect over a long period. The sintered material dissolves very slowly and can thus provide an alkalizing effect for several months.

[0017] Furthermore, the pH value increased by the hydroxide remains relatively stable even over a long period of time.

[0018] Preferably, the sintered hydroxide is arranged directly in front of the filter membrane; in particular, the sintered hydroxide contacts the filter membrane.

[0019] According to a preferred embodiment of the invention, the sintered material, in particular the granules, comprises calcium hydroxide.

[0020] In particular, the material comprises 30 to 95% by weight, preferably 70 to 90% by weight of the material (in the dry state).

[0021] The use of calcium hydroxide not only has an alkalizing effect but also enriches the water being treated with calcium.

[0022] In a further development of the invention, the material, in particular the granules, comprises a mixture with a carbonate.

[0023] In particular, the sintered particles comprise both hydroxide, especially calcium hydroxide, and carbonate, especially calcium carbonate.

[0024] This allows the stability of the sintered particles to be further improved over a longer period of time.

[0025] To produce such granules, a hydroxide powder and a carbonate powder can be mixed and then sintered.

[0026] Preferably, the material is already in particulate form before sintering. To provide dimensionally stable particles during the sintering process, binders, in particular organic binders, can be added to the powder, which evaporate again during the sintering process.

[0027] In one embodiment of the invention, the material, in particular the granules, comprises 5 to 40 wt%, preferably 10 to 20 wt% carbonate.

[0028] In another embodiment, the material contains 0.5 to 5 wt%, preferably 1 to 3 wt%, of an oxide.

[0029] In particular, the material contains silicon oxide.

[0030] The oxide is also present in the individual particles of the granules as a mixture with the other components, especially with the hydroxide and the carbonate.

[0031] Furthermore, the material, especially the granular particles, can contain at least one alkali oxide, particularly sodium and / or potassium oxide. This can influence long-term stability, but also the pH value and calcium release. The alkali oxide, in turn, accelerates the dissolution of the material.

[0032] The alkali oxide can be present in a proportion of 0.1 to 5% by weight, preferably 0.5 to 1.0% by weight.

[0033] Preferably, the granules have a mean particle size of 0.5 to 10 mm, particularly preferably 0.7 to 5 mm, and most preferably 0.8 to 1.5 mm. Such large particles also contribute to long-term stability.

[0034] The particles can be spherical in shape.

[0035] Such spherically shaped particles also contribute to a longer service life of the granules.

[0036] The invention further relates to a method for protecting a water filter from germ formation, in particular a water filter as described above.

[0037] With respect to the flow direction, according to the invention a sintered granulate containing a hydroxide is arranged in front of the filter membrane.

[0038] The granules cause the pH value to rise above 9, preferably to 10 to 12, at least during a stagnation phase in the filter membrane.

[0039] The formation of biofilms can thus be largely avoided in a fairly simple way over longer periods, especially from 3 to 15 months. Description of the drawings

[0040] The subject matter of the invention will below be described with reference to the in Fig. 1 and Fig. The two illustrated examples will be explained in more detail.

[0041] Fig. Figure 1 is a sectional view of a water filter according to a first embodiment of the invention.

[0042] The water filter 1 includes an inlet 2 and an outlet 3.

[0043] The water filter 1 shown here is designed such that it can be installed inline in a water-carrying pipe. The invention also relates to gravity-driven water filters. Furthermore, the water filter can be configured as the outlet of a dispensing point, in particular a tap.

[0044] Water filter 1 provides a chamber in which a membrane is arranged.

[0045] In this embodiment, the membrane is designed as a hollow fiber membrane 5.

[0046] The individual fibers of the membrane are folded over on one side and connected to each other on the other side by means of a potting compound 6.

[0047] In this embodiment, the flow direction D is defined such that the water to be treated enters the water filter 1 via the inlet 2 and enters the hollow fiber membrane 5 from the outside.

[0048] Germs, especially viruses and bacteria, are retained by the hollow fibers 5.

[0049] The treated water exits through the open side of the hollow fiber membrane 5 onto the side of the potting compound 6.

[0050] In addition to the hollow fiber membrane 5, the water filter 6 contains a sintered granulate 7 with spherical particles.

[0051] The particles of granules 7 comprise calcium hydroxide, calcium carbonate, and silicon oxide.

[0052] The granules 7 cause the pH value in the water filter 1 to rise above 9, at least when water is not continuously being drawn off, i.e., during a stagnation phase.

[0053] This counteracts the formation of a biofilm on the concentrate side.

[0054] Fig. Figure 2 shows an alternative embodiment of the invention, in which the water filter 1 is opposite Fig. 1 has a reversed flow direction D.

[0055] The water enters the water filter via inlet 2 and, starting from the open side of the hollow fiber membranes 5 which are embedded in the potting compound 6, passes through the hollow fiber membrane 5, exits from the inside out of the hollow fiber membranes 5 and leaves the water filter 1 via outlet 3.

[0056] In this embodiment, the granules 7 are located in front of the open side of the hollow fiber membrane 5. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] WO 2022 / 101084 A1

[0002]

Claims

[1] Water filter comprising a filter membrane and an alkalizing material, which is formed as a sintered material, in particular as granules, with a hydroxide [2] Water filter according to the preceding claim, characterized by that the material comprises calcium hydroxide, in particular 30 to 95% by weight, preferably 70 to 90% by weight. [3] Water filter according to any of the preceding claims, characterized by that the material comprises a mixture with a carbonate. [4] Water filter according to the preceding claim, characterized by that the carbonate is calcium carbonate. [5] Water filter according to one of the two preceding claims, characterized by that the material contains 5 to 40% by weight, preferably 10 to 20% by weight, carbonate. [6] Water filter according to any of the preceding claims, characterized bythat the material contains 0.5 to 5 wt%, preferably 1 to 3 wt%, of an oxide, in particular silicon oxide. [7] Water filter according to any of the preceding claims, characterized by that the material is in the form of granules with a mean particle size of 0.5 to 10 mm, preferably of 0.7 to 5 mm. [8] Water filter according to any of the preceding claims, characterized by that the granules comprise spherical particles. [9] Water filter according to any of the preceding claims, characterized by that the granules are arranged in front of the filter membrane with respect to the direction of flow. [10] Water filter according to any of the preceding claims, characterized by that the granules contact the filter membrane. [11] Method for protecting a water filter from germ formation, in particular a water filter according to one of the preceding claims, wherein a sintered granulate containing a hydroxide is arranged in front of a filter membrane with respect to the direction of flow. [12] Method according to the preceding claim, characterized by , that the pH value in a stagnation phase in the filter membrane rises to above 9, preferably to 10 to 12, due to the granules.

Images