Drinking water production equipment

Abstract

The utility model relates to a method for obtaining drinking water (3) from raw water (2) through ultrafiltration and reverse osmosis, the drinking water (3) has expected target values of water parameters related to components of the drinking water (3), and the drinking water (3) is provided for use in a fresh water tank (15). In addition, the utility model also relates to drinking water production equipment for executing the method. In order to adjust to a target value, a first amount of water is produced by obtaining a filtrate from the raw water (2) by ultrafiltration and obtaining a permeate from the filtrate by reverse osmosis, the amount of the permeate forming the first amount of water, and a second amount of water is produced by obtaining the filtrate from the raw water (2) by ultrafiltration and obtaining the permeate from the raw water (2) by reverse osmosis. The amount of filtrate forms a second amount of water, and then the first and second amounts of water are mixed to obtain drinking water (3), where the first and second amounts of water are metered such that their mixture has a desired target value.

Description

Technical Field

[0001] The present invention relates to an apparatus for treating raw water, in particular a water softening and desalination apparatus and a membrane filtration system. In particular, the present invention relates to an apparatus for obtaining drinking water from raw water by ultrafiltration (hereinafter abbreviated as UF) and reverse osmosis (hereinafter abbreviated as RO), wherein the drinking water has desired target values of water parameters related to its composition and is provided for use in a fresh water tank. Background Art

[0002] The use of ultrafiltration equipment to produce drinking water from raw water in the form of river, surface, or groundwater is well known. UF is an excellent method for removing suspended particles and microorganisms from raw water to achieve drinking water quality. However, depending on the source and season, raw water may also have a high salinity, which cannot be reduced by UF. Salt is a crystalline compound composed of positively and negatively charged ions that largely determines the taste of drinking water. Most people consider water with a high salt concentration to be undrinkable. Although epidemiological studies to date have not demonstrated a negative impact of high salt levels in drinking water on human health, reducing excessive salt levels in drinking water—that is, desalination—is desirable for taste reasons. This can be achieved through reverse osmosis.

[0003] Whether the salt content is too high and affects the taste depends on the source water, which in turn depends on its salt content. Furthermore, the salt content is not constant year-round but varies with the seasons. Therefore, depending on the salt content of the source water or the expected salt content of the drinking water, RO may or may not be necessary. Therefore, the following arrangements for producing drinking water, consisting of UF units and / or RO units, are well-known in drinking water treatment or purification:

[0004] 1. When the salt content of raw water is lower than the pre-specified limit value, use pure UF unit,

[0005] 2. When the salt content of raw water is higher than the pre-specified limit, use pure RO unit.

[0006] 3. Connecting a UF unit in series with a RO unit, where UF is used as raw water pretreatment for RO, and

[0007] 4. Connect the UF unit and the RO unit in parallel, with the UF forming a bypass around the RO.

[0008] As already mentioned, the first variant has the disadvantage that it does not reduce the salt content of the drinking water and is therefore only suitable if the salt content of the raw water is already low, more precisely below the limit value desired by the user of the drinking water purification system, for example.

[0009] The second variant suffers from the inherent drawbacks of RO. Due to its spiral, tortuous structure and thin composite membranes, it is less effective at retaining microorganisms over the long term. Since RO cannot be backflushed like UF, very high standards are placed on the quality of the RO inlet water. This is achieved through multi-stage pretreatment of the raw water. If substances (fouling) accumulate on the RO membranes over extended periods of operation, chemical cleaning is required. This is done using acidic and alkaline cleaning agents. In backwashing, as is common in UF units, the filter is reversed by pumping filtered water from the purified water side to the raw water side to remove and flush away particles and microorganisms adhering to the raw water side of the membrane. This is not possible with RO filters.

[0010] Furthermore, during filtration operation, RO units must operate at a constant volumetric flow rate, resulting in high water and energy consumption. High energy consumption is due to the extremely small pore size of less than 0.1 nm (so-called molecular-scale). High water consumption is also due to the fact that most of the water simply passes through the membrane and is discarded as the concentrate. Another disadvantage of RO units is that the salt content of the permeate produced by RO cannot be adjusted, resulting in poor water quality because the salt content is always kept to a minimum. Consequently, the water tastes neutral. Consuming drinking water with minimal salt or mineral content can have adverse health consequences. Many human functions require salt or minerals, such as the structure of bones, teeth, and cells. Relevant minerals include sodium, potassium, calcium, magnesium, iodine, zinc, iron, and copper. Consuming drinking water with low salt or mineral content can lead to deficiency symptoms if minerals are not absorbed through other dietary sources. Since the amount of raw water and its salt content fluctuate seasonally, it is desirable to adjust the volumetric flow rate and target salt content in the drinking water to be produced.

[0011] The disadvantages of the aforementioned RO unit also apply to variant 3 (i.e., the series connection of UF and RO). Consequently, the salinity of the drinking water to be produced cannot be regulated, the majority of the valuable UF filtrate is separated by the RO unit as retentate, and the series connection of UF and RO is demanding to control, as the filtrate volume flow must be kept constant, while this filtrate volume flow decreases over time due to clogging of the ultrafilter.

[0012] The parallel connection of a UF unit with an RO unit is also not ideal because the permeate provided by the RO unit is not free of microorganisms and mixes with the filtrate at the outlet of the filtration unit.

[0013] The salinity of water can be determined using various methods. One metric, for example, is the so-called TDS value. This indicates the mass concentration of all substances dissolved in the water (TDS: Total Dissolved Solids), excluding volatile components. The TDS value is expressed in milligrams per liter (mg / l). Drinking water with a TDS value of 900 mg / l is considered salty and unsuitable for drinking. If the raw water salt content is below a TDS of 500 mg / l, a UF unit alone is sufficient for drinking water treatment. Above the TDS limit of 500 mg / l, RO units are typically used to treat the drinking water, which reduces the salt content to a TDS of less than 20 mg / l. Since salt in water forms ions that determine the water's electrical conductivity, the TDS value is also a measure of the water's electrical conductivity. Alternatively, as an alternative to the total dry residue or TDS value, the water's electrical conductivity or its electrical impedance can also be determined to provide quantitative conclusions about the salt content. Utility Model Content

[0014] The present invention aims to provide a drinking water production device for obtaining drinking water, which utilizes the advantages of a combination of ultrafiltration and reverse osmosis to produce healthy and palatable drinking water while avoiding the aforementioned disadvantages of the prior art. In particular, the salinity of the drinking water to be produced should be adjustable, and the drinking water should be produced with minimal water and energy consumption.

[0015] This object is achieved by a drinking water production plant according to the invention for obtaining drinking water from raw water by ultrafiltration and reverse osmosis, wherein the drinking water has desired target values for water parameters related to its composition, the drinking water production plant comprising at least: an ultrafiltration unit for producing filtrate from the raw water; a reverse osmosis unit for producing permeate from the filtrate, which is arranged in series with the ultrafiltration unit via a first closable filtrate line and is connected to a mixing point; and a fresh water tank for providing drinking water for use. A closable second filtrate line connects the ultrafiltration unit to a mixing point while bypassing the reverse osmosis unit, and the drinking water production plant is configured to operate in a first operating mode, wherein in the first operating mode the first filtrate line is open toward the mixing point so as to obtain filtrate from the raw water by ultrafiltration and to obtain permeate from the filtrate by reverse osmosis, the amount of which forms a first water quantity, and in a second operating mode, wherein in the second operating mode the second filtrate line is open toward the mixing point so as to obtain filtrate from the raw water by ultrafiltration, the amount of which forms a second water quantity, wherein the first water quantity and the second water quantity are metered so that their mixture has the desired target value and the mixture forms drinking water.

[0016] According to the present invention, in order to obtain drinking water from raw water by ultrafiltration and reverse osmosis, wherein the drinking water has desired target values of water parameters related to its composition, it is proposed that:

[0017] - producing a first quantity of water by obtaining a filtrate from the raw water by ultrafiltration and obtaining a permeate from the filtrate by reverse osmosis, the quantity of the permeate forming the first quantity of water,

[0018] - producing a second quantity of water by obtaining a filtrate from the raw water by ultrafiltration, the amount of this filtrate forming the second quantity of water, and

[0019] The first and second water quantities are then mixed to obtain drinking water, wherein the first and second water quantities are metered such that their mixture has the desired target value.

[0020] To produce a first quantity of water, the filtrate from the UF unit can be led via a first filtrate line to an RO unit, and the permeate from the RO unit can be led to a mixing point, in particular, to a fresh water tank. Furthermore, to produce a second quantity of water, the filtrate from the UF unit can be led via a second filtrate line directly to a mixing point, in particular, directly to a fresh water tank, while bypassing the RO unit.

[0021] To apply this method, the present invention provides a drinking water production plant for obtaining drinking water from raw water by ultrafiltration and reverse osmosis, wherein the drinking water has desired target values for water parameters related to its composition. The drinking water production plant comprises at least:

[0022] - UF units for producing filtrate from raw water by ultrafiltration,

[0023] an RO unit arranged in series with the UF unit via a closable first filtrate line, the RO unit for producing a permeate by reverse osmosis from the filtrate supplied by the filtrate line, wherein the RO unit is connected (in particular via the permeate line) to a mixing point, and

[0024] A fresh water tank for providing drinking water for consumption. In addition to the first filtrate line, the plant has a closable second filtrate line that connects the UF unit directly or indirectly to the mixing point, bypassing the RO unit. Furthermore, the drinking water production plant is configured to operate in a first operating mode (in which the first filtrate line is open toward the mixing point for producing a first amount of water in the form of a permeate quantity) and a second operating mode (in which the second filtrate line is open toward the mixing point for producing a second amount of water in the form of a filtrate quantity).

[0025] The core concept of the present invention is therefore to achieve desired target values for water parameters by adjusting a predetermined mixing ratio between the permeate of the RO unit, on the one hand, and the filtrate of the UF unit, on the other. This makes it possible to adjust the water parameter in question to any target value, while simultaneously ensuring that the RO unit is operated for only the shortest possible time, thus saving valuable, ultrafiltered water and energy. The design of the drinking water production plant according to the present invention, comprising first and second filtrate lines, ensures high microbiological drinking water quality.

[0026] In one embodiment variant, the raw water can be or will be fed directly to the UF unit. However, it is also possible to pre-treat the raw water, for example by using a pre-filter to remove sand or sediment, to obtain the pre-water that is fed to the UF unit. In this embodiment variant, the raw water can be or will be fed indirectly to the UF unit.

[0027] In a variant embodiment, the filtrate from the UF unit may be or will be directly transferred to the RO unit. However, the filtrate may first be pretreated, for example by adding a scale inhibitor (also known as an antiscalant), to obtain intermediate water that is then transferred to the RO unit. In this variant, the filtrate is or will be indirectly transferred to the RO unit.

[0028] A particularly simple design of the drinking water production plant is achieved by mixing the first and second water quantities simply by introducing them into the fresh water tank. In the fresh water tank, the two water quantities then mix automatically, due to both the flow and turbulence during the introduction of the water and diffusion caused by the concentration differences between the two water quantities. However, another embodiment variant may also provide for mixing the first and second water quantities with the aid of a mixing device. This mixing device may, for example, be a stirring device. This stirring device may be located in the fresh water tank or in a mixing container located upstream of the fresh water tank.

[0029] In a preferred embodiment variant, two water quantities can be produced in batches. That is, the first water quantity is produced first, followed by the second water quantity, or vice versa. Thus, the first water quantity is produced in the first operating mode of the plant, which operates for a first operating time, and in which only the first filtrate line is open. In other words, to produce the first water quantity, the second filtrate line can be closed. Furthermore, the second water quantity is produced in the second operating mode of the plant, which operates for a second operating time, and in which only the second filtrate line is open. In other words, to produce the second water quantity, the first filtrate line is closed. To switch from the first to the second operating mode in batch operation, the first filtrate line is sequentially closed and the second filtrate line is opened, or to switch from the second to the first operating mode in batch operation, the second filtrate line is closed and the first filtrate line is opened, depending on which operating mode is executed first.

[0030] However, an alternative embodiment variant may provide for the production of the second water quantity during the production of the first water quantity. This operating scenario constitutes a temporary simultaneity between the first and second operating modes, which is considered the third operating mode. As will be explained below, the first and second filtrate lines may also be opened simultaneously at least at times to allow at least partial production of the second water quantity during the production of the first water quantity. This shortens the total duration of production of both water quantities. The third operating mode lasts only as long as the second operating mode, because the second water quantity (i.e., solely ultrafiltered drinking water) is produced faster than the first water quantity, and the second filtrate line is closed after the second water quantity is produced. If the second water quantity has not yet been fully produced at this point, only the first filtrate line remains open, resulting in the first operating mode. This switching between the first and third operating modes is thus performed. The second operating mode can begin or end simultaneously with the first operating mode.

[0031] According to a preferred embodiment variant, the first water quantity is obtained by performing ultrafiltration and reverse osmosis within a predefined first operating time, i.e., the first operating mode. Additionally or alternatively, the second water quantity can be obtained by performing only ultrafiltration within a predefined second operating time, i.e., the second operating mode. Thus, the respective operating mode is shut down purely in a time-controlled manner, in particular, in a timer-controlled manner, specifically after the operating time specified for the respective operating mode has expired. This advantageously eliminates the need for sensor systems, in particular for determining the amount of water produced.

[0032] The respective operating modes can be deactivated in a time-controlled manner by a control unit of the drinking water system, in which a corresponding operating time is stored for each operating mode. Thus, the drinking water production system can have a control unit configured to set predetermined operating times for the first and second operating modes, respectively. This control unit can be, for example, a programmable logic controller (PLC).

[0033] To activate the first operating mode or to open the first filtrate line, a valve in the first filtrate line can be opened at the beginning of a first operating time and closed again after the first operating time has expired, thereby deactivating the first operating mode. Similarly, to activate the second operating mode or to open the second filtrate line, a valve in the second filtrate line can be opened at the beginning of a second operating time and closed again after the second operating time has expired, thereby deactivating the second operating mode. The valve is preferably actuated by the control unit.

[0034] The second operating mode can be activated after the first operating mode has been deactivated, so that the two operating modes do not overlap in time, or in other words, they are performed sequentially. This allows for batch production of the first and second water quantities. To this end, the valve in the first filtrate line can be opened and closed again, followed by the valve in the second filtrate line.

[0035] However, as previously mentioned, it is also possible to implement an operating mode in which the first and second operating modes overlap in time, or even in which the second operating mode is run entirely during the first operating mode, since the second operating time is shorter than the first. Thus, the first and second filtrate lines can be opened simultaneously at least at times, so that at least a portion of the second water volume is produced during the production of the first water volume. In terms of operating modes, it is already possible to activate the second operating mode during the operation of the first operating mode simultaneously with, or even before, the first operating mode, and to deactivate the second operating mode during the operation of the first operating mode simultaneously with, or after, the first operating mode, so that the first and second operating modes exist at least at times simultaneously. This method can shorten the time required to produce the total water volume consisting of the first and second water volumes, with the greatest time savings being achieved if the second water volume is produced entirely during the production of the first water volume. Therefore, the following five scenarios can be distinguished for this temporal coexistence:

[0036] - The second filtrate line can be opened before the first filtrate line is opened and closed after the first filtrate line is opened.

[0037] The second filtrate line can be opened simultaneously with the first filtrate line and closed before the first filtrate line is closed.

[0038] The second filtrate line can be opened after the first filtrate line is opened and closed before the first filtrate line is closed.

[0039] The second filtrate line can be opened after the first filtrate line is opened and closed simultaneously with the first filtrate line.

[0040] The second filtrate line can be opened before the first filtrate line is closed and closed after the first filtrate line is closed.

[0041] In one embodiment variant, the first and / or second operating time can be determined or calculated by a control unit. The control unit is therefore configured to determine the first and / or second operating time accordingly. This is preferably done based on water parameter values of the raw water. In other words, in this case, the water parameter of the raw water is first determined, which should serve as the target value for the drinking water to be produced. The first and / or second operating time is then determined based on this target value, in particular by the control unit.

[0042] To determine the water parameters in the raw water, the drinking water production plant can include corresponding sensors, preferably a TDS sensor. The control unit is then configured to determine the first and / or second operating times based on the water parameters measured in the raw water. This results in a standardized system architecture for the drinking water production plant of the present invention, which is adaptable to all installation locations. Furthermore, since the water parameters in the raw water are determined directly, it is no longer necessary to sample and analyze the line water to determine the appropriate first and second operating times.

[0043] The first and second running times can be determined according to the following formula:

[0044] The first and second operating times may be suitably determined according to the following formula: Gl 2:

[0045] and

[0046] Gl 3:V UF =V X -V RO

[0047] Gl 4:

[0048] in

[0049] V RO is the first water amount (permeate amount),

[0050] V UFis the second water amount (filtrate amount),

[0051] V X is the expected total water volume,

[0052] W RT is the water parameter value in the raw water,

[0053] Z FT is the desired target value of the water parameter in drinking water,

[0054] R RO is the percentage retention value of the RO unit, expressed in decimal,

[0055] Q RO is the volume flow rate of the permeate and

[0056] Q UF is the volume flow rate of the filtrate.

[0057] First, use formula G1.1 to determine the required first water volume V RO , that is, the amount of water flowing through the UF unit and the RO unit. When the fresh water tank is initially filled, the desired total water volume V is the sum of the first and second water volumes. X The water tank volume corresponding to the fresh water tank is, for example, between 1000 liters and 2000 liters. RT Measured by the corresponding sensor. Desired target value Z FT is given in advance and is therefore also known. RO It is a specific parameter of the membrane of the RO unit and can be obtained from the operating data of the RO unit manufacturer. In general, it indicates the degree of retention of a certain dissolved substance or salt and varies depending on the membrane and the substance. Usually, the retention value R RO Between 95% and 99%. Then, the first running time T is determined using formula G1.2 OP1 .

[0058] According to formula G1.3, the second water volume V UF The volume that corresponds to the first water volume or fresh water tank must be filled in order to obtain the total water volume in the sum. Then, the second operating time T is determined using formula G1.2 OP2 . Permeate Q RO and filtrate Q UF The volume flow is likewise an operating value of the RO unit or UF unit, which can be taken from the manufacturer's technical specifications and / or the drinking water production plant is operated at this operating value.

[0059] Using the above formula, the first and second operating times for producing the respective first and second water quantities are determined as follows so that the mixture of the first and second water quantities has the desired target value of the water parameter in question, for example, a TDS target value Z between 250 mg / L and 500 mg / L. FT .

[0060] It has been shown that all variables of the above formula remain essentially unchanged during operation of the drinking water production plant. More precisely, the variable is, on the one hand, the water parameter value W in the raw water. RT , which depends on the source of raw water (surface water, well water, river water, etc.) and the desired total water volume V X The latter is important if the method is repeated, that is, at a point in time when the fresh water tank is not completely empty, that is, when V X Use a different value for the water tank volume. In this context, the first and second run times T can also be changed during the method. OP1 、T OP2 .

[0061] In other words, when initially filling an empty fresh water tank with a first total amount of water (preferably the nominal capacity of the fresh water tank), the first and second water amounts (the sum of which constitutes the first total amount of water) can each have an initial first value, and when subsequently refilling the fresh water tank with a replenishment amount, the first and second water amounts can each have a second value, wherein the sum of the second value of the first water amount and the second value of the second water amount then constitutes the second total amount of water, preferably the value of the replenishment amount. The method is then repeated to refill the fresh water tank, wherein the second total amount of water is again produced in this case, i.e., the first and second water amounts each have a second value. The same applies to the first and second operating times. Thus, when initially filling the fresh water tank, the first operating time for producing the first water amount can have a first value, and the second operating time for producing the second water amount can have a second value, while when refilling the fresh water tank, a second value, which is smaller than the first value, can be used for each of the first and second operating times.

[0062] The second total water quantity is preferably adapted to the drinking water consumption. This can be achieved, for example, by measuring the water level in the fresh water tank or the amount of water removed from the fresh water tank and repeating the process when the water level falls below a predetermined limit value or the amount of water removed exceeds a predetermined limit value. Since the corresponding limit values have been determined, the level of the second total water quantity is known. The process is then repeated using second values for the first and second water quantities or second values for the first and second operating times.

[0063] Therefore, the drinking water production plant may include a sensor for detecting the water level in the fresh water tank and / or a device for determining the amount of drinking water removed from the fresh water tank. Furthermore, the control unit may be configured to repeatedly produce the first and second amounts of water when the water level falls below a specified limit or the amount of water removed exceeds a specified limit. To determine whether the water level falls below the specified limit, in the simplest case, a binary water level sensor can be used, which emits a first signal when the water level exceeds the limit and a second signal when the water level falls below the limit. However, a water level sensor that measures the actual water level can also be used, so that the liquid level in the fresh water tank is known at all times. For example, the amount of water removed can be measured using a water meter or a water gauge.

[0064] Once the water level limit value has been exceeded or the water level in the fresh water tank has been determined, the amount of drinking water that must be produced to refill the fresh water tank is known, just as with the direct measurement of the amount of drinking water removed. If the water level limit value is, for example, approximately 50% of the maximum water level, or if the limit value for the amount of water removed is, for example, approximately 50% of the first total water volume or maximum capacity of the fresh water tank, then the respective second values for the first and second water volumes can be 50% of the respective first values. The same applies to the first and second operating times. In this embodiment, since the process flow is repeated when the limit value is exceeded, the volume of drinking water that needs to be produced remains constant.

[0065] As an alternative to the aforementioned limit values, drinking water can be reproduced in a time-dependent manner adapted to consumption. Therefore, in this case, limit values are not used. Rather, the current water level is measured after a certain period of time, for example, every 5 to 30 minutes, or the previously measured amount of applied water removed is determined. In the latter case, this amount corresponds to the second total amount of water to be reproduced. In the case of the water level, the second total amount of water to be reproduced must first be calculated from this. In this embodiment, the amount of drinking water to be reproduced is variable, as it is determined only at the end of the aforementioned period.

[0066] Preferably, the water parameter used is the mass concentration of totally dissolved solids (TDS), salinity, filtrate dry residue, total dry residue, conductivity, electrical resistance, water hardness, or the concentration of chemical substances in drinking water (such as arsenic or fluoride), or another physical parameter of water quality. To determine the salt content in the raw water, a TDS sensor can be used, whose output signal is a measure of the salt content or total dry residue. Preferably, such a sensor is located in the raw water tank. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] The following describes further features, properties and advantages of the drinking water production device of the present invention with reference to embodiments. The accompanying drawings show:

[0068] Figure 1 : A block diagram of the basic structure of the drinking water production equipment of the present utility model;

[0069] Figure 2 : A more detailed block diagram of the drinking water production plant. DETAILED DESCRIPTION

[0070] like Figure 1 As shown, the drinking water production plant 1 of the present invention includes an ultrafiltration unit 14 for producing filtrate from raw water 2 and a reverse osmosis unit 20 for producing permeate from the filtrate as core components. Hereinafter, the ultrafiltration unit 14 will be referred to as the UF unit 14, and the reverse osmosis unit 20 will be referred to as the RO unit 20. The inlet 38 of the RO unit 20 is connected to the outlet 37 of the UF unit 14 via a closable first filtrate line 26, allowing the filtrate from the UF unit 14 to be directed to the RO unit 20 via the first filtrate line 26. The UF unit 14 and the RO unit 20 are thus connected in series. The first filtrate line 26 can be opened and closed by a first valve 34.

[0071] The outlet 39 of the RO unit 20 is connected to a mixing point 15 via a permeate line 28, so that the permeate can be directed to this mixing point 15. The mixing point 15 here consists of a fresh water tank 15, which provides drinking water 3 for consumption. The concentrate 4 produced by the RO unit 20 is also discarded. Furthermore, the outlet 37 of the UF unit 14 is connected to the mixing point 15 via a closable second filtrate line 26, bypassing the RO unit 20. Thus, the second filtrate line 27 is connected in parallel with the first filtrate line 26. The second filtrate line 27 can be opened and closed by a second valve 35.

[0072] The drinking water 3 should have desired target values for water parameters related to its composition. In the present exemplary embodiment, the so-called TDS value (Total Dissolved Solids) is used as the water parameter, which indicates the mass of substances dissolved in the water (i.e., salts) in milligrams per liter. The desired target values in the drinking water are achieved by operating the drinking water production plant 1 in a first operating mode (in which the first filtrate line 26 is open toward the mixing point 15 to produce a first water quantity, which is in the form of a permeate quantity) and in a second operating mode (in which the second filtrate line 27 is open toward the mixing point 15 to produce a second water quantity, which is in the form of a filtrate quantity). The two water quantities are then mixed in the mixing point 15 or fresh water tank 15.

[0073] Thus, a first water quantity is produced by ultrafiltration of raw water 2 to obtain filtrate, and reverse osmosis of the filtrate to obtain permeate (the amount of permeate forms the first water quantity). A second water quantity is produced by ultrafiltration of raw water 2 to obtain filtrate (the amount of filtrate forms the second water quantity). After the first and second water quantities are obtained, they are mixed to produce drinking water 3. The first and second water quantities are designed so that their mixture has the desired water parameters. The water quantities are designed based on the respective operating times of the drinking water production plant 1 in the first and second operating modes. Thus, the first water quantity is produced by performing ultrafiltration and reverse osmosis during a predetermined first operating time. Separately, the second water quantity is produced by performing only ultrafiltration during a predetermined second operating time.

[0074] In addition, if Figure 2 As shown, the drinking water production device 1 includes a control unit 5, which is digitally connected to two valves 34 and 35 via control lines shown by dashed lines, so that these valves can be selectively opened or closed. When the first valve 34 is open, a first operating mode exists. Similarly, when the second valve 35 is open, a second operating mode exists. However, sometimes both valves 34 and 35 can be open simultaneously, which can be considered a third operating mode. Of course, both valves 34 and 35 can also be closed, which means that the drinking water production device 1 is no longer in operation.

[0075] The first and second operating times depend on a water parameter of the raw water 2, namely its TDS value. This value can be determined through laboratory testing, with the operating times then calculated and stored in the control unit. However, the TDS value of the raw water 2 can advantageously be measured by a TDS (total dissolved solids) sensor 12 and provided from this TDS sensor to the control unit 5. Figure 1 This is shown by the dashed line between the sensor 16 and the control unit 5. The control unit 5 can then calculate the first and second operating times based on the measured TDS value. For this purpose, the following formula is used:

[0076] Gl 1:

[0077] Gl 2:

[0078] and

[0079] Gl 3:V UF =V X -V RO

[0080] Gl 4:

[0081] in

[0082] V RO First water amount (permeate amount),

[0083] V UF The second amount of water (filtrate amount),

[0084] V X Expected total water volume,

[0085] W RT Water parameter values in raw water,

[0086] Z FT Desired target values for water parameters in drinking water,

[0087] R RO The retention value of the RO unit, expressed as a percentage,

[0088] Q RO The volume flow rate of the permeate and

[0089] Q UF Volume flow rate of filtrate.

[0090] If the TDS value of the raw water is W RT = 800 mg / L, and the desired TDS target value in drinking water is Z FT = 500 mg / L, in order to fill the fresh water tank 15 with V X = 1000 l of total water volume, and conservatively assuming that the retention value of the RO unit is at least R RO = 96% and the volume flow rate of the filtrate used is Q UF = 260 l / h and the permeate volume flow rate is Q RO =78 l / h, the first operating mode may have T OP1 = 5 hours of operation time, while the second operation mode may have T OP2 = 2.4 hours of operation time. Then, the control unit 5 opens the first valve 34 for 5 hours and the second valve 34 for 2.4 hours. If the TDS value in the raw water is, for example, 1200 mg / L and the desired TDS target value in the drinking water is 250 mg / L, assuming that V X 、R RO , Q UF and Q RO The value of is the same as above, then the first operation mode can have an operation time of 10.6 hours, and the second operation mode can have an operation time of 0.7 hours. Then, the control unit 5 opens the first valve 34 for 10.6 hours and opens the second valve 34 for 0.7 hours.

[0091] It is advantageous to carry out the two modes sequentially, i.e. to produce the first and second water quantities in batches. This makes it possible to use a small UF unit, since it is not necessary to produce filtrate for both the mixing tank and the RO inlet at the same time.

[0092] Figure 2 Shown is a drinking water production device 1 of the present invention, and Figure 1 The device 1 in FIG. 1 is different from the device 1 in FIG. 2 and has additional components. Therefore, raw water 2 is provided in a raw water tank 10, which is connected to the inlet 36 of the UF unit 14 via a raw water line 25. A raw water pump 11 is arranged in the raw water line 25 for pumping the raw water 2 from the storage tank 10 at a pressure P of, for example, 0.7 bar. F The raw water 2 is then delivered to the UF unit 14. Furthermore, a TDS sensor 12 is connected to the raw water line 25 for determining the TDS value of the raw water 2. Furthermore, a pre-treatment unit in the form of a pre-filter 13 is arranged in the raw water line 25 between the raw water pump and the raw water line 25 for filtering out coarse particles such as sand from the raw water.

[0093] The UF unit 14 can be composed of one or more ultrafiltration modules connected in parallel, for example, four such modules. Such an ultrafiltration module preferably includes a plurality of hollow fiber ultrafiltration membranes. The membranes are designed to retain particles larger than 9.5 nm. The membranes separate the raw water side, which flows into an inlet 36, from the filtrate side, which leads to at least one outlet 37. During operation, a maximum pressure difference of 1.2 bar, also known as the transmembrane pressure (TMP), can exist between the raw water side and the filtrate side.

[0094] To remove particles that accumulate on the membranes over time on the raw water side and thus clean the UF unit 14, water can be directed through the membranes in the reverse direction, a process commonly referred to as backwashing. Water is pumped from the filtrate side to the raw water side. For this purpose, a backwash pump 22 is provided in the drinking water production plant 1. This backwash pump is connected to the outlet 37 of the UF unit 14 via a backwash line 30. A backwash valve 40 separates the backwash line 30 from the outlet 37 of the UF unit 14. The backwash water, laden with accumulated particles, is discharged on the raw water side via a retentate line 32 and allowed to settle in a discharge system 41.

[0095] In a variant embodiment, the retentate line 32 can be connected to the same inlet as the raw water line 26. In this case, a shutoff valve is provided between the inlet 36 and the raw water line 25 and between the inlet 36 and the retentate line 32, respectively, for selectively connecting the raw water line or the retentate line to the raw water side of the UF unit 14, depending on the operating mode (filtration operation, backwash operation). Alternatively, the raw water side can have two inlets 36, one of which is connected to the raw water line 25 and the other to the retentate line 32. In this case, a shutoff valve is also provided in each of the raw water line 25 and the retentate line 32.

[0096] exist Figure 2 In the illustrated variant embodiment, the outlet 37 of the UF unit 14 is also connected to a fresh water tank 15 via two parallel lines 26 and 27, through which a certain amount of water can be introduced into the tank 15. A central line section (into which the retentate line 30 is also connected) connects the outlet 37 to a branching junction 23, at which the central line section divides into a first filtrate line 26 and a second filtrate line 27. The second filtrate line 27 is directly connected to the fresh water tank 15, so that the unsalted ultrafiltrated water of the UF unit 14 can be supplied to the fresh water tank 15 via the second filtrate line. For example, Q UF =260 l / h of filtrate flow to achieve this. In the second filtrate line 27 there is a second valve 35 for selectively opening or closing the second filtrate line.

[0097] The first filtrate line 26 connects the branching junction 23 or the outlet 37 of the UF unit 14 to the inlet 38 of the RO unit 20, thereby supplying the filtrate from the UF unit 14 to the RO unit. A first valve 34 is located in the first filtrate line 27 for selectively opening or closing the first filtrate line. Furthermore, a high-pressure pump 18 and a downstream addition unit 19 are arranged in the second filtrate line 26. This addition unit 19 is used to meter antiscalant, i.e., a chemical used to clean the membranes, during cleaning. Therefore, the addition unit 19 is located between the high-pressure pump 18 and the RO unit 20.

[0098] As with the UF unit 14, the RO unit 20 can also be composed of one or more reverse osmosis modules connected in parallel to increase the amount of permeate produced per unit time. The reverse osmosis module has a reverse osmosis membrane that separates an inlet side from an outlet side. As water permeates through the membrane, permeate, i.e., substantially desalinated purified water, is produced on the outlet side. This purified water can flow out through the first outlet 39 of the RO unit 20. A permeate line 28 connects the first outlet 39 of the RO unit 20 to the fresh water tank 15, so that a certain amount of ultrafiltered water desalinated by the permeation of the RO unit 20 can be provided to the fresh water tank 15 via the permeate line. The permeate can be, for example, in the form of Q RO = 78 l / h volume flow. The transmembrane pressure on the osmotic membrane can be about P RO =4.8bar.

[0099] The reverse osmosis membrane overflows as specified, resulting in an inlet side with an inflow and an outlet. Since water permeates through the membrane between the inflow and outlet sides, the salt concentration on the outlet side is higher than on the inflow. Consequently, the water flowing out of the outlet side forms concentrate 4. The inflow side is connected to inlet 38, and the outlet side is connected to second outlet 42. A concentrate line 29 is connected to this second outlet for introducing concentrate 4 into a concentrate tank 21 connected to concentrate line 29, for example, with a capacity of 150 liters. Overflow pipe 31 discharges the overflowed concentrate 4 for sedimentation in a discharge system 41. Concentrate 4 is used as backwash water, so a backwash line 30 is connected to concentrate tank 21.

[0100] A level sensor 17 is located in the fresh water tank 15 and is configured to determine whether the water level has fallen below a specified limit level. Preferably, the level sensor 17 is configured to measure the actual level of drinking water in the tank at all times. Using the level sensor 16, it is possible to determine whether and when a desired amount of drinking water must be produced based on a desired TDS target value. Furthermore, a further TDS sensor is located in the fresh water tank 15 to measure the TDS value of the produced drinking water. This value can be used to check whether the drinking water production system is operating correctly.

[0101] Figure 2 Also shown is a central control unit 5, to which the sensor data of the raw water TDS sensor 12, the sensor data of the TDS sensor 16 for fresh water in the fresh water tank 15, and the water level are transmitted via corresponding sensor lines (dash-dotted lines) and which is operatively connected to the pumps 11, 18, 22 and valves 34, 35, 40 via corresponding control lines (dashed lines) in order to control them.

[0102] When the drinking water production plant 1 starts operating, the TDS value of the raw water 2 is measured by means of the sensor 12 and provided to the control unit. This control unit then uses the above-mentioned formula to calculate a first operating time for the first operating mode, for generating a first water quantity in the form of a permeate quantity, and a second operating time for the second operating mode, for generating a second water quantity in the form of a filtrate quantity, more precisely in such a way that the total water quantity, which is a mixture of the first and second water quantities, has the desired TDS target value. The TDS value of the raw water thus determines the operating time of the UF unit 14 when operating alone and the operating time of the combination of the UF unit and the RO unit. Advantageously, in this case, the hydraulic structure of the drinking water production plant 1 does not need to be modified for different TDS values in the raw water. Instead, adjustments to the changes in the TDS value can be made by simply recalculating the first and second operating times, which is an adjustment made entirely in terms of control technology.

[0103] Here too, the first and second water quantities are produced in sequence. Here, first the first water quantity is produced (reverse osmosis batch) and then the second water quantity (ultrafiltration batch).

[0104] A further advantage of the drinking water production plant 1 is that all hydraulic lines 25, 26, 27, 28, 29, 30, 31 are formed by hoses, preferably with plug connectors, rather than threaded rigid pipes, which increases the compactness of the plant and simplifies assembly.

[0105] It should be pointed out that the above description is merely illustrative for the purpose of explanation and in no way limits the scope of protection of the present invention. Features of the present invention expressed as "can", "for example", "preferably", "optional", "ideal", "advantageous", "when necessary", "suitable", etc. can be regarded as purely optional and do not limit the scope of protection, which is determined only by the claims. If the elements, components, process steps, values or information listed in the above description have known, similar or foreseeable equivalents, these equivalents are included in the present invention. Similarly, the present invention also includes any changes, modifications or variations of the embodiments, which involve the replacement, addition, change or omission of elements, components, process steps, values or information, as long as the basic idea of the present invention remains unchanged, regardless of whether the changes, modifications or variations lead to improvements or degradations of an embodiment.

[0106] Although the above utility model description lists many physical, non-physical or process-related features related to one or more specific embodiments, these features can also be applied independently of the specific embodiments, at least when they do not require the presence of more features. Conversely, these features related to one or more specific embodiments can be combined with each other as needed, and can also be combined with other disclosed or undisclosed features of disclosed or undisclosed embodiments, at least when these features do not exclude each other or do not lead to technical incompatibility.

[0107] Reference Signs List

[0108] 1 Drinking water production equipment

[0109] 2 Raw water

[0110] 3. Drinking water

[0111] 4 Concentrates

[0112] 5 Control Unit

[0113] 10 Raw water tank

[0114] 11 Raw water pump

[0115] 12 TDS sensors

[0116] 13 Pretreatment unit / prefilter

[0117] 14 Ultrafiltration unit / UF unit

[0118] 15 Fresh water tank / mixing point

[0119] 16 TDS sensor

[0120] 17 Liquid level sensor

[0121] 18 High-pressure pump

[0122] 19 Add Unit

[0123] 20 Reverse Osmosis Unit / RO Unit

[0124] 21 concentrate tanks

[0125] 22 Backwash pump

[0126] 23 Diversion

[0127] 24 output units / water points

[0128] 25 Raw water pipeline

[0129] 26 First filtrate pipeline

[0130] 27 Second filtrate pipeline

[0131] 28 Permeate line

[0132] 29 Concentrate line

[0133] 30 Backwash pipeline

[0134] 31 Overflow pipe

[0135] 32 Retentate pipeline

[0136] 33 Output pipeline

[0137] 34 First Valve

[0138] 35 Second valve

[0139] Entrance to 36 UF unit

[0140] 37 UF unit outlet

[0141] 38 Inlet of reverse osmosis unit

[0142] 39 First outlet of reverse osmosis unit

[0143] 40 Backwash valve

[0144] 41 Exhaust system

[0145] 42 Second outlet of reverse osmosis unit

Claims

1. A drinking water production plant (1) for obtaining drinking water (3) from raw water (2) by ultrafiltration and reverse osmosis, wherein the drinking water (3) has desired target values for water parameters related to its composition, the drinking water production plant comprising at least: an ultrafiltration unit (14) for producing a filtrate from the raw water (2); a reverse osmosis unit (20) for producing a permeate from the filtrate, which is arranged in series with the ultrafiltration unit (14) via a first closable filtrate line (26), and is connected to a mixing point (15); and a fresh water tank for providing the drinking water (3) for use, characterized in that A closable second filtrate line (27) connects the ultrafiltration unit (14) to the mixing point (15) while bypassing the reverse osmosis unit (20), and the drinking water production plant (1) is configured to operate in a first operating mode, in which the first filtrate line (26) is open toward the mixing point (15) to obtain filtrate from the raw water (2) by ultrafiltration and permeate from the filtrate by reverse osmosis, the amount of which forms a first water quantity, and in a second operating mode, in which the second filtrate line (27) is open toward the mixing point (15) to obtain filtrate from the raw water (2) by ultrafiltration, the amount of which forms a second water quantity, The first amount of water and the second amount of water are metered such that their mixture has the desired target value and the mixture forms drinking water (3).

2. The drinking water production device (1) according to claim 1, characterized in that The mixing point (15) is the fresh water tank.

3. The drinking water production device (1) according to claim 1 or 2, characterized in that The drinking water production plant has a control unit (5) which is configured to set a first operating mode to operate for a predetermined first operating time and a second operating mode to operate for a predetermined second operating time.

4. The drinking water production device (1) according to claim 1 or 2, characterized in that The drinking water production device has a control unit (5) which is used to set the first operating mode to run for a predetermined first operating time and the second operating mode to run for a predetermined second operating time. The first operating mode and the second operating mode are run in sequence.

5. The drinking water production device (1) according to claim 3, characterized in that The drinking water production plant has a sensor (12) for determining a water parameter value of the raw water (2), and the control unit (5) is configured to determine the first and second operating times as a function of the water parameter value.

6. The drinking water production device (1) according to claim 3, characterized in that The drinking water production device has a sensor (17) for detecting the water level in the fresh water tank or a device for determining the amount of water removed from the fresh water tank, and the control unit (5) is configured to repeatedly produce the first and second water quantities when the water level falls below a specified limit value or the amount of water removed exceeds a specified limit value.

7. The drinking water production device (1) according to claim 1, characterized in that The drinking water production plant is configured to close the second filtrate line (27) for producing a first amount of water and to close the first filtrate line (26) for producing a second amount of water.

8. The drinking water production device (1) according to claim 1, characterized in that The drinking water production plant is configured to simultaneously open the first and second filtrate lines (26, 27) at least sometimes in order to produce at least a portion of the second water quantity during the production of the first water quantity.

9. The drinking water production device (1) according to claim 1 or 2, characterized in that: The water parameter is the mass concentration of completely dissolved solid material, salinity, filtrate dry residue, total dry residue, electrical conductivity, electrical resistance, water hardness or the concentration of chemical substances in the drinking water.

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