Filter material for water treatment

Abstract

The invention relates to: a first filter material for water treatment comprising a first granulate containing calcium carbonate and a second granulate containing magnesium oxide, the first and the second granulate each independently having a bulk density of 1.00 to 1.40 t / m3; a second filter material for water treatment comprising 55 to 85 wt.% of a first granulate containing calcium carbonate and 15 to 45 wt.% of a second granulate containing magnesium oxide, in each case in relation to the sum of the quantities of the first and second granulate; a method for manufacturing the filter material; a filter containing the filter material; a use of the filter material for treating water; and a water treatment method.

Description

[0001] Filter material for water treatment

[0002] The invention relates to a first filter material for water treatment, a second filter material for water treatment, and a method for producing the

[0003] filter material, a filter comprising a filter material, the use of a filter material, and a water treatment process.

[0004] In drinking water treatment, filter materials are used to reduce the acidity of the water; these typically contain mineral components. Filter materials containing calcium carbonate and / or magnesium oxide are of particular importance. Semi-calcined dolomite, which is formed during the calcination of dolomite, also belongs to this group of filter materials.

[0005] Semi-calcined dolomite consists mostly of calcium carbonate and

[0006] Magnesium oxide. Granules made from semi-calcined dolomite exhibit particularly good deacidification properties in the treatment of drinking water.

[0007] While calcium carbonate-based granules are not reactive enough for certain water treatment applications, magnesium oxide-based granules can be too reactive for some, resulting in a pH value exceeding what is acceptable for drinking water. Semi-calcined dolomite granules, on the other hand, exhibit an excellent reactivity profile, which results from the beneficial interaction of their various components.

[0008] Furthermore, filter materials made of semi-calcined dolomite also meet the high safety and quality requirements that must be met in drinking water treatment. These requirements are regulated in the "Ordinance on the Quality of Water Intended for Human Consumption (Drinking Water Ordinance - TrinkwV)". According to the Drinking Water Ordinance, only a few substances are permitted for use in drinking water treatment.

[0009] Deacidification and pH adjustment of drinking water is permitted.

[0010] One disadvantage of granules made from semi-calcined dolomite is that they must be produced from dolomite rock using complex, time-consuming, and energy-intensive manufacturing processes. For processing, ground semi-calcined dolomite is mixed with dolomite hydrate, granulated, and recarbonated. The production of granules from semi-calcined dolomite is therefore a comprehensive, time-consuming, labor-intensive, and energy-intensive process.

[0011] Another disadvantage of granules made from semi-calcined dolomite is that further fine-tuning of the water's pH value is not easily possible. The ratio of magnesium oxide to calcium carbonate in the raw dolomite is already predetermined. Any further addition of magnesium oxide and / or calcium carbonate during the manufacturing process of semi-calcined dolomite must be precisely controlled, as this can negatively affect the material's granulation behavior.

[0012] Other filter materials containing calcium carbonate and magnesium oxide are already known. However, these do not exhibit the same outstanding properties.

[0013] Deacidification properties of semi-burnt dolomite.

[0014] DE 1 592 133 Al, for example, describes a granular filter material for

[0015] Deacidification of water consisting predominantly of calcium compounds, where the core of the filter grain consists mainly of calcium hydroxide and the shell mainly of porous calcium carbonate. The core of the filter grain may also contain magnesium oxide. Due to the relatively high proportion of

[0016] According to DE 1 592 133 Al, the granular filter material containing calcium hydroxide exhibits a reactivity profile that differs from that of semi-calcined dolomite.

[0017] Deacidification behavior. Consequently, there remains a need for new filter materials that exhibit similarly excellent deacidification properties in drinking water treatment as granules made from semi-calcined dolomite. Furthermore, such filter materials would have to ensure that the treated water meets the high standards.

[0018] Meets the requirements of the Drinking Water Ordinance.

[0019] The present invention therefore aims to provide a filter material suitable for the treatment of drinking water.

[0020] The filter material should have similar deacidification properties to granules made from semi-burnt dolomite.

[0021] Furthermore, the invention aims to provide a filter material with which water can be treated to meet the high quality requirements of the Drinking Water Ordinance. In particular, the invention aims to provide a filter material that ensures, during water treatment, that the water does not exceed the pH limit of 9.5 stipulated in the Drinking Water Ordinance. The filter material should also meet the requirements for treatment substances specified in the Drinking Water Ordinance.

[0022] Furthermore, the present invention aims to provide a filter material that can be manufactured in a simple and cost-effective manner.

[0023] Finally, the present invention aims to provide a filter.

[0024] to provide a system that enables high-quality and stable water deacidification over several months.

[0025] One or more of these problems are solved by the products described in claims 1, 10 and 12 and by the use described in claim 16. Advantageous embodiments of the invention are specified in the dependent claims and are explained in detail below.

[0026] The present invention relates to a first filter material for water treatment, comprising a first granule containing calcium carbonate and a second granule containing magnesium oxide, wherein the first and the second granule each independently have a bulk density of 1.00 to 1.40 t / m³ 3 exhibit.

[0027] Surprisingly, it has been shown that such a filter material is exceptionally well suited for water treatment, especially for drinking water. Furthermore, the pH value of drinking water can be precisely adjusted using the filter material according to the invention.

[0028] The deacidification behavior of the filter material according to the invention is very similar to that of granules made from semi-calcined dolomite and remains stable even over several weeks with a daily operating time of almost 10 hours. The filter material according to the invention ensures uniform deacidification of the

[0029] The quality of drinking water is guaranteed. Water treated with the filter material according to the invention meets the quality requirements of the Drinking Water Ordinance and does not exceed the pH limit of 9.5. Furthermore, during water treatment, the filter material removes iron and manganese and remineralizes the drinking water, thereby further improving its quality.

[0030] Without wanting to be bound to a specific scientific theory, the excellent deacidification behavior of the filter material seems to be due to the

[0031] The interaction of the first and second granules is to be attributed to this. The filter material according to the invention behaves like granules made of semi-calcined dolomite, although it comprises granules of different types. This homogeneous deacidification behavior appears to be primarily due to the corresponding bulk density of the first and second granules. Both the first and the second granules each independently exhibit a bulk density of 1.00 to 1.40 t / m³. 3 When the filter material is applied, it produces a homogeneous mixture of both.

[0032] Granules whose composition remains largely unchanged even over extended periods when exposed to water. This prevents segregation within the filter, ensuring a stable ratio of first and second granules throughout the entire filter.

[0033] Granules within the meaning of the invention comprise grains, each grain being an agglomerate of smaller particles. Consequently, pure powders are not granules within the meaning of the invention.

[0034] At a bulk density of less than 1.00 t / m³ 3 For the first and / or second granules, the granules are not sufficiently stable to react uniformly, even when using large quantities of water in industrial water treatment. Such granules may exhibit detachment and irregularities. However, if the first and / or second granules have a bulk density of more than 1.40 t / m³ 3If the particles from which the granules are formed do not form a loose bond with each other, but are packed too densely, resulting in unstable granules. Granules obtained in this way are not sufficiently stable for applications in industrial drinking water treatment and do not exhibit the required reactivity.

[0035] deacidification process.

[0036] According to an advantageous embodiment of the filter material according to the invention, the first and / or the second granules, each independently of each other, have a bulk density of 1.10 to 1.38 t / m³ 3 , preferably from 1.15 to 1.35 t / m 3 or, more preferably, from 1.20 to 1.32 t / m 3If the first and / or the second granules have such a bulk density, a particularly constant pH level of drinking water can be achieved with the filter material. According to a particularly preferred embodiment of the invention, both the first and the second granules have a bulk density of 1.10 to 1.38 t / m³. 3 , preferably from 1.15 to 1.35 t / m 3 or, more preferably, from 1.20 to 1.32 t / m 3 , on. The more similar the bulk densities of the first and second granules of the

[0037] The higher the quality of the filter material, the more uniform and stable its effectiveness in water treatment. This is particularly advantageous when...

[0038] Bulk density of the first granules not more than 20%, in particular not more than 10% or not more than 5% above or below the bulk density of the second granules, based on the bulk density of the first and second granules in t / m³ 3This means that, for example, if the bulk densities of the first and second granules differ by a maximum of 10%, and the second granule has a bulk density of 1.15 t / m³ 3 The first granules have a bulk density of 1.04 to 1.26 t / m³ 3 exhibits.

[0039] Methods for determining bulk density are known to those skilled in the art.

[0040] In particular, the determination of the bulk density of the inventive

[0041] Granules according to DIN EN 12902, section 5.2, particularly preferably according to DIN EN 12902:2004, section 5.2, are produced. The granules according to the invention are granular material as defined in Table 1 in section 5.2.4 of DIN EN 12902:2004.

[0042] The deacidification behavior of the filter material according to the invention has proven to be particularly effective and consistent when the filter material contains the first granules in an amount of 55 to 85 wt.%, preferably in an amount of 60 to 80 wt.%, more preferably in an amount of 62 to 75 wt.%, more preferably in an amount of 65 to 70 wt.%, or most preferably in an amount of 66 to 68 wt.%, based on the sum of the amounts of the first and second granules. If the filter material contains the first and second granules in such a ratio, the deacidification behavior of the filter material according to the invention corresponds to

[0043] Filter material, especially that made from granules of semi-calcined dolomite. Furthermore, in this case, the filter material exhibits a particularly long-lasting stability.

[0044] Deacidification behavior.

[0045] Particularly good results in water treatment can be achieved if the first granule of the filter material contains calcium carbonate in an amount of at least 90 wt.%, preferably at least 93 wt.%, preferably at least 95 wt.% or particularly preferably at least 96 wt.%, based on the

[0046] The total dry weight of the first granules contains [something]. According to a particularly preferred embodiment of the invention, the first granules contain [something].

[0047] Calcium carbonate in an amount of approximately 97 wt.%, based on the

[0048] Total dry weight of the first granules. According to a further embodiment, the first granules contain calcium carbonate in an amount of at least 97 wt.%, at least 98 wt.% or at least 99 wt.%, based on the

[0049] Total dry weight of the first granules. According to a further particularly preferred embodiment of the invention, the first granules fulfill the

[0050] Purity criteria for calcium carbonate according to standard DIN EN 1018:2013, section 5. Such a high proportion of calcium carbonate in the first granule ensures that the quality of the water treatment remains stable over numerous water cycles. Furthermore, a filter material in which the first granule contains such a high amount of calcium carbonate exhibits a particularly high deacidification potential. With a first granule containing the aforementioned calcium carbonate proportions or purity, the treated water also exhibits a particularly low turbidity of less than 2 NTU, preferably less than 1.5 NTU, or most preferably less than 1 NTU.

[0051] According to a further preferred embodiment of the invention, the second granule of the filter material contains magnesium oxide in an amount of at least 80 wt.%, preferably at least 85 wt.%, or particularly preferably at least 90 wt.%, based on the total dry weight of the second granule. According to a further embodiment of the invention, the second granule contains magnesium oxide in an amount of at least 93 wt.%, at least 95 wt.%, at least 97 wt.%, at least 98 wt.%, or at least

[0052] 99 wt.%, based on the total dry weight of the second granules. According to a particularly preferred embodiment of the invention, the second granules preferably have a magnesium oxide purity corresponding to the

[0053] Requirements of the standard DIN EN 16004:2012-02, section 4. If the second granulate has such a high proportion of magnesium oxide, the pH value of water can be adjusted particularly efficiently. Furthermore, the pH value of the water can be adjusted very precisely with such a filter material. With a second granulate containing the aforementioned magnesium oxide proportions or the aforementioned

[0054] Furthermore, the treated water exhibits a particularly low turbidity of less than 2 NTU, preferably less than 1.5 NTU or particularly preferably less than 1 NTU, in addition to its magnesium oxide purity.

[0055] Methods for determining the turbidity of a water sample are known to those skilled in the art. The turbidity of the water sample can be determined in particular by nephelometry. For this purpose, the procedure according to the standard can be used in particular.

[0056] DIN EN ISO 7027:2000 can be used.

[0057] The first granule may contain other components besides calcium carbonate. It has proven particularly advantageous if the first granule contains magnesium oxide in an amount of no more than 1% by weight, and especially no more than 0.5% by weight, based on the total dry weight of the first granule. If the first granule contains only these small amounts of magnesium oxide, the pH value of the treated water can be precisely adjusted and predicted.

[0058] Significantly higher amounts of magnesium oxide (e.g., over 10 wt.%) in the first granules may cause short-term and / or rapid increases in pH (peaks), which are undesirable in water processing.

[0059] According to one embodiment, the first granules contain as further components magnesium carbonate, preferably in amounts of 0.01 to 2.0 wt.%, free calcium oxide, preferably in amounts of 0.1 to 2.0 wt.%, iron and aluminum oxide, preferably together in amounts of 0.01 to 0.5 wt.%, and / or silica, preferably in amounts of 0.05 to 0.5 wt.%, each based on the total dry weight of the first granules. Granules with some or all of these further components are comparatively inexpensive and simultaneously exhibit excellent water treatment quality.

[0060] The second granule may contain other components besides magnesium oxide. According to one embodiment of the invention, the second granule contains calcium carbonate in an amount of at most 3 wt.%, in particular at most 2 wt.%, at most 1 wt.% or at most 0.5 wt.%, based on the

[0061] Total dry weight of the second granule. This ensures that the second granule has a high deacidification potential.

[0062] According to one embodiment, the second granule contains as further components free calcium oxide, preferably in a concentration of 0.1 to 2.0 wt.%, iron and aluminum oxide, preferably together in a concentration of 0.1 to 2.0 wt.%, and / or silica, preferably in a concentration of 0.05 to 2.0 wt.%, each based on the total dry weight of the second granule. Granules with some or all of these further components are comparatively inexpensive and at the same time exhibit excellent properties.

[0063] Water treatment quality.

[0064] Unless otherwise specified, the content or purity of

[0065] Calcium carbonate determined according to DIN 12485, in particular according to DIN EN 12485:2017-10.

[0066] Unless otherwise specified, the magnesium oxide content in the

[0067] Dry matter in particular according to DIN EN 12485, especially according to DIN EN 12485:2017-10, point 6.9.

[0068] When determining the content of a substance according to one of the analytical methods listed in the standard DIN EN 12485, in particular DIN EN 12485:2017-10, it must be noted that the analytical methods are to be carried out on material obtained after determining the loss on ignition at 550 °C. At this temperature, for example, calcium hydroxide is converted to calcium oxide. Similarly, at this temperature, magnesium hydroxide is converted to magnesium oxide. Therefore, when determining the magnesium oxide content in the dry matter according to DIN EN 12485, in particular section 6.9 of DIN EN 12485:2017-10, both the magnesium oxide contained in the material before loss on ignition and the

[0069] Magnesium hydroxide is measured equally as magnesium oxide in the dry matter. Magnesium oxide in the dry matter thus includes, in particular, both magnesium oxide and magnesium hydroxide present in the sample before loss on ignition. Similarly, when determining free calcium oxide according to DIN EN 12485, especially according to DIN EN 12485:2017-10, section 6.8, both the calcium oxide and the calcium hydroxide present in the material before loss on ignition are included.

[0070] equally recorded as free calcium oxide. Free calcium oxide thus includes, in particular, calcium oxide contained in the sample before loss on ignition and

[0071] Calcium hydroxide.

[0072] Basically, the first and / or second granules can be in a wide variety of shapes. For example, the first and / or second granules can be cylindrical, spherical, lenticular, rectangular, or...

[0073] The granules can be cube-shaped or prismatic. If the first and second granules are essentially spherical, independent of each other, the filter material can be introduced into the filter particularly evenly and efficiently. Furthermore, the degradation of the spherical granules during the deacidification process is especially uniform, ensuring that the filter material remains consistent and stable even after prolonged use.

[0074] provides a water treatment result. According to a particularly preferred embodiment, both the first and the second granules are a component of the water treatment process.

[0075] Essentially spherical granules.

[0076] In principle, the size of the first granule for the filter material according to the invention can be within a wide range. It has proven particularly advantageous if the first granule has a particle size distribution of 0.01 to 8 mm, preferably 0.1 to 6 mm, more preferably 0.3 to 4 mm, or most preferably 0.5 to 3.2 mm, with a proportion of undersized particles of less than 10 wt.%, preferably a maximum of 2 wt.%, and an oversized particle size distribution of less than 10 wt.%, preferably a maximum of 7 wt.%. If the first granule has such a particle size distribution, an optimal surface-to-volume ratio for water treatment is achieved. Furthermore, with this size of first granule, the water can pass through the filter material in the filter efficiently and simultaneously interact sufficiently with the granule to ensure complete water treatment.

[0077] The size of the second granule can be selected within a wide range. It has proven particularly suitable for the filter material if the second granule has a particle size distribution of 0.01 to 12 mm, preferably 0.1 to 10 mm, more preferably 0.2 to 5 mm, or most preferably 0.5 to 2.5 mm, with a proportion of undersized particles of less than 10 wt.%, preferably a maximum of 3 wt.%, and an oversized particle size distribution of less than 10 wt.%, preferably a maximum of 9 wt.%. With this particle size distribution, the

[0078] The reactivity of the second granule towards water is particularly advantageous. Furthermore, with this size of granule, the water can easily pass through the filter material and simultaneously interact sufficiently with the granule to ensure complete water treatment.

[0079] In this context, a particle size distribution group, according to standard DIN EN 12901:1999, comprises all particle sizes between two sieve sizes, with the group being described by these sieve sizes as the largest and smallest particle sizes. The largest particle size is the upper sieve size when examining a particle size distribution, and the smallest particle size is the lower sieve size when examining the

[0080] Particle size distribution. The oversize fraction corresponds to the mass fraction in % (m / m) of a particle mixture that is retained by the test sieve with the largest screen size for the respective particle size group. The undersize fraction corresponds to the mass fraction in % (m / m) of a particle mixture that passes through the test sieve with the smallest screen size for the respective particle size group.

[0081] Methods for measuring the grain size distribution are known to those skilled in the art. The grain size distribution can be determined in particular by means of sieving experiments.

[0082] According to a further preferred embodiment of the invention, the filter material according to the invention has such a reactivity that raw water is treated with the filter material according to the invention within an EBCT value (Empty Bed Contact Time; at 10 °C) of less than 20 minutes, preferably less than 15 minutes, more preferably less than 12 minutes, particularly preferably less than 10 minutes, to such an extent that the water subsequently has a calcite dissolution capacity of less than 5 mg / l.

[0083] Preferably, the raw water treated with molded bodies according to the invention has a water temperature of about 5 to 15 °C, a pH value of less than or equal to 7.25, and a base capacity up to pH 8.2 (K B 8 , 2) greater than or equal to 0.2 mmol / l and an acid capacity down to pH 4.3 (Ks 4,3) of greater than or equal to 0.5 mmol / L. Preferably, the specified EBCT value is achieved with an open filter with a filter material layer thickness of 1000 to 2000 mm. The filter velocity is advantageously 10 m / h.

[0084] The calcite dissolution capacity is calculated in particular according to the standard DIN 38404 C 10, preferably according to the standard DIN 38404-10:2012-12 (Title: German standard methods for the examination of water, wastewater and sludge - Physical and physicochemical material properties (Group C) - Part 10: Calculation of the calcite saturation of water (C 10)).

[0085] The EBCT value describes, in particular, a measure of the time that raw water to be treated is in contact with the treatment medium in a container, assuming that all the raw water flows through the container at the same velocity. The EBCT value can be calculated as the quotient of the volume of the treatment medium particles divided by the volumetric flow rate.

[0086] According to a preferred embodiment of the invention, the

[0087] The filter material according to the invention essentially consists of the first granules containing calcium carbonate and the second granules containing magnesium oxide. When it is stated here that the filter material essentially consists of the first and the second granules, it is meant that the combined amount of the first and second granules is at least 95% by weight, preferably at least

[0088] 98 wt.%, based on the total dry weight of the filter material.

[0089] According to a further preferred embodiment of the invention, the filter material according to the invention consists of the first granules containing

[0090] Calcium carbonate and the second granules containing magnesium oxide.

[0091] According to a further embodiment of the invention, the filter material according to the invention consists of a first granulate, which is essentially composed of

[0092] The first granule consists of calcium carbonate, and a second granule which consists essentially of magnesium oxide. When it is stated here that the first granule consists essentially of calcium carbonate, this means that the amount of calcium carbonate in the first granule is at least 95 wt.%, in particular at least 97 wt.%, more preferably at least 98 wt.%, or most preferably at least

[0093] 99% by weight, based on the total dry weight of the first granules. When it is stated here that the second granules consist essentially of...

[0094] When the invention states that the second granule contains magnesium oxide, it means that the amount of magnesium oxide in the second granule is at least 95% by weight, in particular at least 97% by weight, more preferably at least 98% by weight, or most preferably at least 99% by weight, based on the total dry weight of the second granule. Even more preferably, the first and / or second granule consists of calcium carbonate or magnesium oxide, respectively. The invention further relates to a second filter material for water treatment, which contains 55 to 85% by weight of a first granule containing calcium carbonate and 15 to 45% by weight of a second granule containing magnesium oxide, each based on the sum of the amounts of the first and second granules. This second filter material is ideally suited for water treatment and behaves very similarly to granules made of semi-calcined dolomite during water treatment.

[0095] According to a preferred embodiment, the first and the second

[0096] Granules, each independently of the others, with a bulk density of 1.00 to 1.40 t / m³ 3 at such a bulk density, the second filter material

[0097] in particular, no segregation effects in the filter.

[0098] What has been said in connection with the first filter material according to the invention regarding the first granules also applies equally to the first granules of the second filter material according to the invention.

[0099] What has been said in connection with the first filter material according to the invention regarding the second granulate also applies equally to the second granulate of the second filter material according to the invention.

[0100] Furthermore, the invention relates to a method for producing a filter material according to the invention. The method according to the invention for producing a

[0101] The filter material according to the invention comprises at least the following steps:

[0102] a. Providing a first granulate containing calcium carbonate and a second granulate containing magnesium oxide, wherein the first and the second granulate, each independently of each other, have a bulk density of 1.00 to 1.40 t / m³ 3 exhibit;

[0103] b. Mixing the first and second granules to produce the

[0104] Filter material. The inventive method allows for the production of a homogeneous and well-made filter material.

[0105] obtained mixed filter material.

[0106] According to a preferred embodiment of the inventive method, the mixing in process step b. takes place in a mixer selected from the group consisting of a rotary drum mixer, a trough mixer, a pan mixer, and a mechanical stirred mixer. A particularly homogeneous filter material can be obtained with these mixers. The rotary drum mixer has proven to be particularly well-suited for mixing the first and second granules.

[0107] What has been said in connection with the first filter material according to the invention regarding the first granules also applies equally to the first granules of the

[0108] Method according to the invention for producing the filter material.

[0109] What has been said in connection with the first filter material according to the invention regarding the second granulate also applies equally to the second granulate of the inventive method for producing the filter material.

[0110] The invention further relates to a filter containing the inventive

[0111] Filter material.

[0112] According to a preferred embodiment of the filter according to the invention, the filter comprises at least a first and a second layer, wherein the first layer comprises a filling material and the second layer comprises the filter material according to the invention. In this way, particularly economical water treatment is enabled.

[0113] In addition, the filling material layer ensures that the filter material layer is particularly stable and does not get stirred up.

[0114] In principle, all common fillers known to experts can be used as filler material. Fillers made from support gravel, sand, diatomaceous earth, silica gel, molecular sieves, zeolite, cellulose, cellulose derivatives, carbon fibers, ceramics, and synthetic resins have proven particularly suitable.

[0115] Rock flour, fiberglass, silicates, glass beads, and mixtures thereof were highlighted. These packing materials exhibit excellent properties for use in a drinking water treatment filter.

[0116] According to a preferred embodiment of the filter according to the invention, the packing material has a particle size distribution of 0.1 to 12 mm, preferably 0.5 to 10 mm, more preferably 1 to 8 mm, or particularly preferably 2 to 6 mm, with a fraction of undersized particles of less than 15 wt.%, preferably a maximum of 10 wt.%, and a fraction of oversized particles of less than 15 wt.%, preferably a maximum of 10 wt.%. Packing materials with such a particle size distribution have proven to be particularly suitable for use in filters for

[0117] Drinking water treatment was highlighted. With this type of grain size, the water can flow through the filling material evenly and consistently.

[0118] According to a further preferred embodiment of the invention, the filter has a diameter of 100 to 3500 mm and / or a height of 500 to 10000 mm. A filter with a diameter of 200 to 2000 mm has proven particularly suitable for water treatment. A particularly preferred height of the filter is 2000 to 4000 mm. With these dimensions, the filter is especially well suited for drinking water treatment and can ensure time- and cost-effective water treatment.

[0119] What has been said in connection with the first filter material according to the invention regarding the first granules also applies equally to the first granules of the filter material contained in the filter according to the invention.

[0120] The statements made regarding the first filter material according to the invention and the second granules also apply equally to the second granules of the filter material contained in the filter according to the invention. The invention further relates to the use of the filter material according to the invention for the treatment of water, preferably for deacidification and / or

[0121] Remineralization of water. The use of the filter material according to the invention for the deacidification and / or remineralization of drinking water is particularly preferred.

[0122] Furthermore, the invention relates to the use of the filter according to the invention for the treatment of water, preferably for the deacidification and / or remineralization of water. The use of the filter according to the invention for the deacidification and / or remineralization of drinking water is particularly preferred.

[0123] What has been said in connection with the first filter material according to the invention regarding the first granules also applies equally to the first granules of the filter material for the uses according to the invention.

[0124] What has been said in connection with the first filter material according to the invention regarding the second granulate also applies equally to the second granulate of the filter material of the uses according to the invention.

[0125] Furthermore, the invention relates to a water treatment process, in particular for drinking water treatment, comprising at least the steps

[0126] a. Providing a filter containing a filter material comprising a first granule containing calcium carbonate and a second granule containing magnesium oxide, wherein the first and the second granule, each independently of each other, have a bulk density of 1.00 to 1.40 t / m³ 3 exhibit, b. introducing water into the filter,

[0127] c. Bringing the introduced water into contact with the filter material, d. Discharging the water previously brought into contact with the filter material from the filter. According to a preferred embodiment of the invention

[0128] In this water treatment process, the water is passed through the filter at a speed of 5 to 30 m / h, preferably 8 to 20 m / h, or particularly preferably 10 to 15 m / h. This allows for a particularly efficient [process / method / process - context needed].

[0129] Water treatment processes are used that provide treated water of excellent quality.

[0130] According to a further preferred embodiment, the contact time of the water with the filter material in process step c. is from 1 to 30 min, preferably from 5 to 15 min or particularly preferably from 6 to 10 min. This contact time has proven to be sufficient for water treatment and at the same time allows for a high water throughput.

[0131] According to a further preferred embodiment of the invention

[0132] During the water treatment process, filter material is replenished in the filter after 5 to 15%, especially 8 to 10%, of the filter material volume required for the treatment goal, i.e., the volume originally placed in the filter, has been removed.

[0133] The amount of filter material introduced is consumed. The refill volume of filter material is preferably calculated as the difference between the volume of filter material required for the treatment goal and the volume of filter material already in the filter at the time of refilling. This ensures consistently stable water treatment over the long term.

[0134] To prevent the filter from becoming clogged with impurities from the raw water, rinsing the filter containing the filter material according to the invention has proven advantageous, according to a preferred embodiment. According to one embodiment, the filter is rinsed with an air-water mixture for 1 to 30 minutes, preferably for approximately 10 minutes, and finally with water, before being brought into contact with water in process step b. The statements made regarding the first filter material according to the invention also apply equally to the filter material in the invention.

[0135] Filter material used in water treatment processes.

[0136] What has been said in connection with the first filter material according to the invention regarding the first granules also applies equally to the first granules of the

[0137] water treatment process according to the invention.

[0138] What has been said in connection with the first filter material according to the invention regarding the second granulate also applies equally to the second granulate of the water treatment process according to the invention.

[0139] The invention is explained in more detail below by means of an example, which, however, serves only for illustration and is not limiting.

[0140] Example

[0141] Fig. 1 Figure 1 shows the pH value of water which was treated with the

[0142] was treated with the filter material according to the invention

[0143] A filter with a diameter of 300 mm and a height of 3000 mm was first filled with 34 kg of support gravel (300 mm high) with a grain size of 2.0 to 3.15 mm (oversize and undersize fraction less than 10% by weight). Subsequently, 40 kg of filter material (500 mm high) was added to the filter. This filter material consisted of 26.7 kg of a first granulate (Akdolit® Hydro-Calcit CG) containing approximately 97% by weight calcium carbonate.

[0144] Dry weight of the first granules, and 13.3 kg of a second granule (Akdolit® Hydrolit-MG) containing approximately 95 wt.% magnesium oxide, based on the

[0145] Dry weight of the second granulate, combined. The filled filter was then rinsed with raw water for 10 minutes to ensure a

[0146] To avoid filter clogging.

[0147] Subsequently, raw water with a temperature of approximately 9 °C, a pH value of approximately 7.25 and a base capacity up to pH 8.2 (KB 8) was used. , 2) of 0.2 mmol / l and an acid capacity up to pH 4.3 (Ks 4.3) of 1.6 mmol / l with a

[0148] Water flow velocity of 0.3 to 0.6 m 3 / h pumped through the filter. The daily runtime was between 5 and 10 hours. After a

[0149] Water treatment volume of approximately 100 m³ 3 10 kg of the above were used

[0150] The described filter material was added to the filter material already in the filter. The filled filter was then rinsed again for approximately 10 minutes, as described above.

[0151] After a total water treatment volume of 600 m³ 3The filter was emptied and refilled with fresh support gravel (10 kg, grain size 3.15 to 5.6 mm, oversize and undersize fraction less than 10% by weight; filter height 300 mm) and fresh filter material (19.5 kg total; 13 kg Akdolit® Hydro-Calcit CG and 6.5 kg Akdolit® Hydrolit-Mg) and rinsed with raw water for 6 minutes. The raw water was then returned to the filter at a flow rate of 0.3 to 0.6 m / s. 3 The filter was pumped with a flow rate of 1 / hour for 5 to 10 hours daily. Refilling occurred when the filtrate's pH fell below the target level of 7.7.

[0152] The treated water was regularly tested for pH, hardness, and turbidity. As can be seen in Figure 1, the pH of the treated water remained between 7.5 and 9 throughout the entire period, and thus well below the lower and upper limits for drinking water according to [relevant standard / regulation].

[0153] The Drinking Water Ordinance was removed. The filter material remained sufficiently active for deacidifying the water even over several months. At the same time, the activity of the filter material did not decrease.

[0154] The pH value was not too high at any given time, but remained stable throughout the entire test period. Furthermore, no significant fluctuations in pH were observed. The water hardness was checked at regular intervals (approximately every two weeks). The values ​​for calcium and magnesium ions were determined by ion chromatography according to DIN EN 14911:1999, and the values ​​for the bicarbonate concentration by titrimetry according to DIN 38409-H7:2005. The theoretical values ​​are Ca 2+ :Mg 2+ :HC03= 1 : 1 : 4, the measured values ​​at Ca 2+ :Mg 2+HC03 = 1.0 : 1.4 : 4.6. The magnesium oxide component therefore reacted somewhat faster than the calcium carbonate component. Overall, the

[0155] However, the measured values ​​were in good agreement with the expected theoretical hardening values.

[0156] The turbidity of the treated water was checked by nephelometry at regular intervals of approximately two weeks. The turbidity of the treated water was tested according to standard DIN EN ISO 7027:2000. In the vast majority of measurements, the treated water exhibited a very low turbidity of less than 0.1 NTU. In none of the measurements was the turbidity limit of 1 NTU specified in the Drinking Water Ordinance exceeded.

[0157] The raw water treated with the filter material according to the invention therefore met the quality requirements of the Drinking Water Ordinance. The filter material according to the invention is thus ideally suited for the treatment, in particular the deacidification and / or remineralization, of drinking water.

Claims

A filter material for water treatment comprising:-          a first granulate containing calcium carbonate,-          a second granulate containing magnesium oxide, wherein the first and the second granulate each independently have a bulk density of 1.00 to 1.40 t / m3,characterized in that the filter material contains the first granulate in an amount of 55 to 85% by weight, based on the sum of the amounts of the first and the second granulate.The filter material according to claim 1, characterized in that the first and / or the second granulate each independently has a bulk density of 1.10 to 1.38 t / m3.The filter material according to claim 1, characterized in that the first granulate contains calcium carbonate in an amount of at least 90% by weight, based on the total dry weight of the first granulateThe filter material according to claim 1, characterized in that the second granulate contains magnesium oxide in an amount of at least 80% by weight, based on the total dry weight of the second granulate.The filter material according to claim 1, characterized in that the first granulate contains magnesium oxide in an amount of at most 1% by weight based on the total dry weight of the first granulate.The filter material according to claim 1, characterized in that the second granulate contains calcium carbonate in an amount of at most 3% by weight, based on the total dry weight of the second granulate.The filter material according to claim 1, characterized in that the first and the second granulate are each independently a spherical granulate.The filter material according to claim 1, characterized in that the first granulate has a particle size range of 0.01 to 8 mm, with an undersize percentage of less than 10% by weight, and with an oversize percentage of less than 10% by weight.The filter material according to claim 1, characterized in that the second granulate has a particle size range of 0.01 to 12 mm, with an undersize percentage of less than 10% by weight and with an oversize percentage of less than 10% by weight.A filter material for water treatment comprising:-          55 to 85% by weight of a first granulate containing calcium carbonate,-          15 to 45% by weight of a second granulate containing magnesium oxide,in each cased based on the sum of the amounts of the first and the second granulate, wherein the first and the second granulate each independently has a bulk density of 1.00 to 1.40 t / m3.Filter material according to claim 10, characterized in that the first and the second granulate is defined as in claim 2A filter containing a filter material according to claim 1.A method for using a filter material according to claim 1 for treatment of water.

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