Water purification system and its operation method based on in-line measurement of total organic carbon

Abstract

This application relates to a water purification system and method with in-line measurement of total organic carbon (TOC) content.

Description

Technical Field

[0001] This application relates to a water purification system and method with inline measurement of total organic carbon (TOC) content.

Background Art

[0002] Background In applications such as the pharmaceutical, life science, and semiconductor fields, for example, natural water or tap water ( "tap water") may not be pure enough because it may contain contaminants that can cause unwanted side reactions and / or negatively affect the reproducibility of the analysis or manufacturing process. Therefore, depending on the target application, the purity of the water must be improved by partially or as much as possible removing the contaminants contained in the water. The highest purity water, often designated as "ultra-high purity" or "Type I" water according to ASTM D1193-06, is characterized, for example, by a resistivity of at least 18.0 MΩ·cm and a total organic carbon (TOC) of at most 5 ppb.

[0003] Water purification systems that enable the production of ultra-pure water or Type I water are known as such. An integrated water purification system designed to purify water from tap water includes various water purification steps such as filtration, reverse osmosis, electro-deionization, ultraviolet irradiation treatment, and ion exchange steps. Generally, such a purification system includes a first purification stage in which tap water is purified to a first purity grade (e.g., Type 2 or lower as defined in ASTM D1193-06), and a second purification stage in which the pre-purified water from the first purification stage is further purified to a higher purity (e.g., Type 1 as defined by ASTM D1193-06) and then distributed from the system and can be used.

[0004] Purifying water to ultra-high purity levels is challenging because the acceptable levels of contaminants are extremely low. Therefore, to avoid the accumulation of contaminants within the water purification system and distribution section, for example, if water is not being distributed from the system, the purified water needs to be continuously recirculated throughout the system, for example, through continuous recirculation via the first and second purification stages. To ensure that the distributed water meets the desired purity, users are interested in a water purification system that can continuously or at least periodically monitor numerous properties of the purified water. While some of these properties can be measured relatively easily, determining the total organic carbon (TOC) content has proven to be quite difficult.

[0005] US5,677,190A discloses a measuring cell and circuit for measuring the electrical properties of a liquid sample during exposure to ultraviolet irradiation. In one embodiment for measuring TOC in water by oxidation to CO2, ultraviolet irradiation is generated by a low-pressure mercury lamp. The water sample in the measuring cell is irradiated until the conductivity no longer increases, which means that all organic components originally present in the water have been oxidized. The difference in conductivity before and after irradiation is then calculated as the total organic carbon content. Although this method is very accurate, it is quite time-consuming and also requires additional equipment specifically for determining TOC content.

[0006] US5,272,091A discloses a method for predicting the organic carbon content of water discharged from a water purification system, where the water is derived from a past water source, such as an ultraviolet light source included in the water purification system. A value for the purified water is then obtained using the change in reference mode resistivity combined with the purification mode resistivity, and this can be correlated with the carbon content of the water discharged from the water purification system to predict the carbon content of the water discharged from the water purification system.

[0007] EP0498888A1 discloses a method for measuring the total amount of organic matter in ultrapure water. This method involves irradiating ultrapure water, whose resistivity is set to a known constant value through ion exchange treatment, with ultraviolet light. The decrease is calculated by subtracting the resistivity values ​​of ultrapure water continuously measured at different locations from the aforementioned constant resistivity value, and the total organic carbon content is determined based on the correlation between the amount of CO2 generated and the decrease.

[0008] The methods disclosed in US5,272,091A and EP0498888A1 propose an economical and simple way to determine TOC content using equipment already present in a water purification system. However, since the TOC content is determined immediately after (i.e., downstream of) the UV irradiation source but before (i.e., upstream of) the second purification step, the values ​​obtained in this manner may not necessarily correspond to the actual TOC content of the water distributed from the water purification system, and therefore there is still room for improvement. Furthermore, if the first purification stage fails to perform completely, but such a lack of performance is compensated for by the second purification stage, these methods may lead to false alarms of higher-than-desired TOC levels.

[0009] Therefore, there is a need in industry for improved purification systems and methods that enable the determination of the total organic carbon (TOC) content at the point of distributing ultrapure water from a water purification system, preferably without requiring the installation of additional, possibly technically complex and / or expensive, components in the water purification system. Preferably, such purification systems and methods should not also lead to increased maintenance requirements. [Overview of the Initiative]

[0010] overview To our surprise, the inventors have found that the above objectives can be achieved individually or in any combination by the water purification system and method of the present invention.

[0011] Therefore, this application is, A water purification system (100), which is described below: (a) A purification stage (104) comprising, in order, an ultraviolet irradiation treatment step (105) and a polisher (107), preferably consisting essentially of the same; and (b) A device (106) located downstream of the ultraviolet irradiation step (105) and upstream of the polisher (107) for measuring the total organic carbon content, (c) Measurement loop Includes, The measurement loop includes the purification stage (104) and a device (106) for measuring total organic carbon. The aforementioned water purification system is provided.

[0012] Therefore, this application also relates to the operation process of a water purification system (100), The water purification system (100) is as follows: (a) A purification stage (104) comprising, in order, an ultraviolet irradiation treatment step (105) and a polisher (107), preferably consisting essentially of the same; and (b) A device (106) located downstream of the ultraviolet irradiation step (105) and upstream of the polisher (107) for determining the total organic carbon content. (c) Measurement loop, Includes, The measurement loop includes the water purification stage (104) and a device (106) for measuring total organic carbon. The process here involves the following steps: (1) Passing water through the purification stage (104) to obtain purified water; and (2) Determining the total organic carbon content contained in the purified water by passing the purified water through the measurement loop and using the device (106), including, The aforementioned operation process is also provided. [Brief explanation of the drawing]

[0013] Brief explanation of the drawing [Figure 1] FIG. 1 shows an exemplary schematic view of the present water purification system including a connection line C1 and a two-way or three-way valve (111). [Figure 2] FIG. 2 shows an exemplary schematic view of the present water purification system including a connection line C1 and two valves (111a) and (111b).

[0014] [Figure 3] FIG. 3 shows an exemplary schematic view of the present water purification system including a connection line C2. [Figure 4] FIG. 4 shows a schematic illustration of a preferred water distribution section (109), a device (108) for determining the total organic carbon content, a valve (110), and a portion of a recycle line (R). [Figure 5a] FIG. 5a shows an exemplary schematic view of the flow of water through the present water purification system including a connection line C1 and a two-way or three-way valve (111) in the distribution mode. [Figure 5b] FIG. 5b shows an exemplary schematic view of the flow of water through the present water purification system including a connection line C1 and a two-way or three-way valve (111) in the measurement mode. [Figure 5c] FIG. 5c shows an exemplary schematic view of the flow of water through the present water purification system including a connection line C1 and a two-way or three-way valve (111) in the recycling mode.

[0015] [Figure 6a] FIG. 6a shows an exemplary schematic view of the flow of water through the present water purification system including a connection line C2 in the distribution mode. [Figure 6b] FIG. 6b shows an exemplary schematic view of the flow of water through the present water purification system including a connection line C2 in the measurement mode. [Figure 6c] FIG. 6c shows an exemplary schematic view of the flow of water through the present water purification system including a connection line C2 in the recycling mode. [Figure 7]FIG. 7 shows the total organic carbon content (TOC) of the water coming from the first purification stage of Example 1 (refer to the continuous line) and the distributed water (refer to the dashed line). [Figure 8] FIG. 8 shows the resistivity curve and the TOC curve of Example 2.

[0016] [Figure 9] FIG. 9 shows the resistivity curve and the TOC curve for Example 4.

[0017] In FIGS. 5a, 5b, 5c, 6a, 6b, and 6c, the dotted lines and symbols indicate the components of each depicted water purification system that are not used in the specific mode represented by each figure. Throughout this application, identical components etc., including the figures, are denoted by corresponding reference numerals. In the figures, the arrows are used to indicate the general direction of the flow of water through the water purification system of this application.

Mode for Carrying Out the Invention

[0018] Detailed Description As used herein, the term "upstream" is used to mean the direction opposite to the flow of water within the water purification system, i.e., the direction towards the water inlet. In other words, going upstream means the direction from the distribution section to the water inlet. As used herein, the term "downstream" is used to mean the direction along the general flow of water within the purification system, i.e., the direction towards the water outlet. In other words, going downstream means the direction from the water inlet to the water distribution section. In this specification, in the context of a water purification stage, the terms "essentially consisting of," "essentially consisting of (third-person singular subject)," and "essentially consisting of" are used to indicate that each stage does not have further means for water purification (such as means for removing contaminants contained in the water), but nevertheless, it may include one or more auxiliary devices selected from a non-limiting group consisting of, for example, temperature sensors, flow sensors, pressure sensors, conductivity measuring devices, flow controls, and valves.

[0019] As used herein, the terms “water purification flow,” “measurement loop,” and “recycle flow” are used to describe a continuously liquid-connected flow path for water passing through the water purification system described herein. As used herein, the terms “UV” and “ultraviolet” are used generally, and unless otherwise limited, to refer to electromagnetic radiation having wavelengths of at least 100 nm and up to 400 nm.

[0020] Generally speaking, this application relates to a water purification system for producing ultra-high purity, i.e., Type I water. In particular, this application relates to a water purification system comprising (a) a purification stage, (b) a device for measuring total organic carbon (TOC) content, and (c) a measuring loop. The purification stage shown below (a), which for clarity is generally referred to throughout this application as the “second purification stage,” includes, and preferably consists essentially of, an ultraviolet irradiation step and a polisher. The device for measuring the total organic carbon content is located downstream of the ultraviolet irradiation step in the second purification stage and upstream of the polisher. Such a device for measuring the total organic carbon content is preferably a device for measuring conductivity, which may be referred to as a "conductivity cell" throughout this application. Such a conductivity cell is generally associated with a temperature sensor.

[0021] The measurement loop includes, preferably essentially consists of, an ultraviolet irradiation treatment step and a polisher (i.e., a second purification stage) and a device located between the ultraviolet irradiation treatment step and the polisher for measuring the total organic carbon content. A preferred water purification system includes, in order, a water inlet, a water purification flow, and a recycling line(R), and preferably consists essentially of these. The water inlet, for example equipped with a solenoid valve, serves to introduce water from an external source into the water purification system. Such water from an external source is generally of lower purity than Type I water and may come from, for example, a public water system ("tap water") or a system that distributes deionized water or Type II water. For the purposes of this application, it should be noted that the water inlet is considered to represent the upstream point in the water purification system.

[0022] The water purification flow includes, in order, a pump, a first (or preceding) purification stage, a second purification stage, and a distribution section, preferably consisting of these in essence, all as defined herein. The first purification stage purifies the water to a first water purity grade, preferably a first water purity grade higher than the water purity grade of the water introduced into the current water purification system through the water inlet mentioned above ("supply water"). The purification media included in the first purification stage is not particularly limited. For example, it may be selected depending on the purity of the feedwater supplied to the water purification system. Preferably, the first purification stage includes one or more purification media selected from the group consisting of cationic ion exchangers, anionic ion exchangers, and activated carbon. Therefore, the first purification stage preferably reduces the levels of ionic and / or organic contaminants. The water coming out of the first purification stage should have a resistivity of up to 18.2 MΩ·cm at 25°C and very low levels of organic pollutants, provided that the first purification stage is functioning perfectly.

[0023] Preferably, the second purification purifies the water to a second water purity grade that is higher than the first water purity grade. Preferably, the second purification stage includes, in order, an ultraviolet irradiation treatment step and a polisher, and preferably consists essentially of them. For the first and second purification stages, and especially for the second purification stage, the polisher is preferably a disposable device, such as a disposable cartridge containing the respective purification mediums as defined above.

[0024] Preferably, the ultraviolet irradiation device includes an ultraviolet irradiation source that emits radiation having a wavelength of at least 150 nm, and such ultraviolet irradiation source is preferably selected from the group consisting of low-pressure mercury lamps, cold cathode mercury lamps, and excimer lamps. In such UV irradiation devices, UV irradiation at least partially oxidizes organic contaminants and ions, particularly carbonate ions (CO3). 2- This leads to the formation of ions or bicarbonate ions (HCO3). The presence and, in particular, the concentration of such ions can then be determined by the temperature of the water, which is detected by a temperature sensor using a conductivity cell with relevant temperature compensation. With the increase in conductivity due to the additional ions produced by the oxidation of organic pollutants in the water, the concentration / level of organic pollutants in the water can be calculated using a dedicated algorithm. This algorithm is not particularly limited. Further details regarding the determination of the total organic carbon content can be found in International Publication No. 2018 / 153822A1, which is incorporated herein by reference; however, it should be noted that such determinations and calculations are well known in the art and generally do not need to be described in detail.

[0025] It should be noted that, in addition to using ultraviolet irradiation, organic pollutants in water can be oxidized by thermal oxidation, chemical oxidation (e.g., by adding peroxides such as hydrogen peroxide), ultraviolet persulfate oxidation, and any other method selected from a non-exclusive list consisting of any combination thereof. Furthermore, while this description uses ultraviolet irradiation to describe this water purification system and method, such descriptions apply equally to other methods. Nevertheless, oxidation by ultraviolet irradiation is preferred for this water purification system and method. Preferably, the polisher includes one or more purification media selected from the group consisting of activated carbon, cation ion exchangers, and anion ion exchangers. Preferably, downstream of the polisher and upstream of the distribution section, the purified water passes again through a conductivity cell having an associated temperature sensor to determine its conductivity, and consequently its total ion concentration, and therefore its purity and suitability for its intended purpose. Thus, this conductivity cell, if present, also allows the user to evaluate the good overall function of the current water purification system.

[0026] The distribution section allows the ultrapure water produced by the water purification system to be drawn from one or more water outlets. The one or more water outlets may be located directly from the rest of the water purification system, or they may be located a few meters further away, for example. If there are one or more outlets, they may be arranged sequentially or in parallel, but in parallel is preferred. Preferably, each water outlet includes a distribution valve that allows control of the dispensing rate and volume of purified water. The distribution valve may be a solenoid valve of the type that usually has a closed channel. Furthermore, each outlet preferably includes a “bypass” that allows water to be circulated through the distribution section even when purified water is not being distributed from the water outlet, for example, when the water purification system is in recycling mode. Such a “bypass” may be considered part of a recycling line(R) or part of a combined water purification flow and recycling flow / recycling line(R), for example, when the water purification system is in recycling mode. An exemplary water outlet is disclosed, for example, in EP1814007A1.

[0027] Preferably, at the point of use, i.e., upstream of the purified water outlet contained within the distribution section, the distribution section includes a filter element which preferably comprises a 0.22 μm membrane or any other suitable purification means. Such a filter element is preferably adapted to remove trace contaminants such as bacteria, pyrogens, endocrine disruptors, and / or volatile organic compounds, but these are just some non-limiting examples. The Recycle Line (R) liquidally connects the water purification flow from a location downstream of the distribution section to a location downstream of the water inlet and upstream of the pump. The water purification flow and / or recycling line(R) is adapted to bypass the first purification stage, thereby establishing a measurement loop.

[0028] Such a bypass may be achieved by the water purification system, which includes a connecting line C1 that liquidally connects the water purification flow from a branching point located downstream of the pump and upstream of the first purification stage to a location downstream of the first purification stage and upstream of the second purification stage, particularly upstream of the ultraviolet irradiation treatment stage. Therefore, the water purification system preferably includes a two-way or three-way valve located in the water purification flow at the branching point. This valve allows control of the water flow along the water purification flow or along the connection line C1, thereby allowing bypassing the first purification stage.

[0029] Alternatively, the water purification system preferably includes two valves: a first valve located in the water purification flow downstream of the branching point and upstream of the first purification stage, and a second valve located in the connection line C1. By closing the first valve and opening the second valve, the water flow reaches directly from the pump through the connection line C1 to the ultraviolet irradiation step of the second purification stage. Conversely, by opening the first valve and closing the second valve, the water flow reaches the first purification stage, passes through it, and then reaches the second purification stage. The first valve may be, for example, a two-way valve. The second valve may be, for example, a two-way valve or a check valve.

[0030] Optionally, in addition to the two valves used in combination, a check valve may be placed in the water purification flow downstream of the pump and upstream of the branching point. The check valve blocks the backflow of water, i.e., prevents water from flowing towards the pump and the water inlet. Alternatively, such a bypass can be achieved by a water purification system that includes a connecting line C2 which liquidally connects the recycling line(R) to the water purification flow downstream of the first purification stage and upstream of the second purification stage, particularly upstream of the ultraviolet irradiation treatment stage. Preferably, the connecting line C2 includes a circulation pump.

[0031] The application also relates to a process for operating a water purification system, the water purification system comprising (a) a purification stage, which for clarity is generally referred to throughout this application as the “second purification stage,” (b) a device for determining the total organic carbon content, the device described herein, located downstream of the ultraviolet irradiation step and upstream of the polisher, and (c) a measurement loop as defined herein, wherein the process comprises (1) passing water through the purification stage to obtain purified water, and (2) passing the purified water through the measurement loop and using the device to determine the total organic carbon content contained in the purified water.

[0032] Preferably, the present application relates to a process for operating a water purification system, wherein the water purification system includes (a') a water inlet; (b') a water purification flow as defined herein; and (c') a recycle flow (R) as defined herein, and the following steps (1') Providing water through the water inlet; (2') Pass water through a water purification flow to obtain purified water; (3') Distribute the purified water obtained in step (2'); and (4') The level of total organic compounds is determined by bypassing the first purification stage and passing the purified water through a measurement loop, and the total organic carbon content is determined by a device for determining the total organic carbon content. This includes the following steps.

[0033] Following step (3') of distributing the purified water obtained in step (2'), the water purification system is changed (for example, manually by an operator) or preferably automatically switched from the distribution mode to the post-distribution or measurement mode of step (4'), for example, by closing the distribution valve and opening the valve of the recycling line (R). Preferably, in step (4') of the process, the first purification stage is bypassed by blocking the water purification flow downstream of the branching point and upstream of the first purification stage, allowing water to pass directly to the second purification stage via the connecting line C1, the water purification system preferably includes a two-way valve or a three-way valve at the branching point, or the first valve is located in the water purification flow downstream of the branching point and upstream of the first purification stage, and the second valve is located in the connecting line C1.

[0034] Alternatively, in step (4') of the process, the first purification stage is preferably bypassed by a connection line C2 as defined herein, by forcing water through the connection line C2. Preferably, the process further includes recycling the purified water by sequentially passing it through a water purification flow and a recycling line (R) following step (4'). In this specification, the term “recycle” is used to indicate repeated passage through the water purification flow and the recycling line (R). Such recycling makes it possible to keep the levels of potential contaminants in the purified water as low as possible, particularly when the purified water is not being distributed.

[0035] This system and method makes it possible to determine the total organic carbon content of purified water, i.e., distributed water, at the point of use, while simultaneously utilizing equipment / devices / components already included in the water purification system and part of the water purification flow. This also allows for a simplified design of the water purification system compared to conventional water purification systems, where the total carbon content is determined downstream of the UV irradiation device, but in the water purification flow upstream of the polisher.

[0036] The following provides a more detailed explanation of the current water purification system and the processes for operating it, with reference to illustrative schematic diagrams. Note that the definitions and descriptions given above for each component of this water purification system also apply to the corresponding elements shown in the diagrams.

[0037] A schematic example of a preferred water purification system (100) of this application is shown in Figure 1. The system (100) preferably comprises, in order, a water inlet (101), a pump (102), a first purification stage (103), a second purification stage (105), an optional device for conductivity measurement (108) ("conductivity cell"), and a distribution section (109). The system (100) also includes a recycling line (R).

[0038] To be purified, water is supplied to a water purification system (100) via a water inlet (101). It then passes into a water purification flow, which includes a pump (102), a first purification stage (103), a second purification stage (104) for obtaining purified ultrapure water, and a distribution section (109) from which the purified water may be distributed. Optionally, the water purification flow may include a conductivity cell (108) downstream of the second purification stage (104) and upstream of the distribution section (109).

[0039] The second purification stage (104) includes, in order, an ultraviolet treatment stage (105) and a polisher (107), and preferably consists essentially of them. Between the ultraviolet treatment stage (105) and the polisher (107), i.e., downstream of the ultraviolet treatment stage (105) and upstream of the polisher (107), the water purification system (100) includes a device (106) for determining the total organic carbon content.

[0040] The device (106) includes a conductivity measuring cell (106a) and a temperature sensor (106b). If a conductivity cell (108) is present, it includes a conductivity measuring cell (108a) and a temperature sensor (108b) located downstream of the polisher and upstream of the distribution section. The distribution section (109) includes a water distribution valve (109b) that can open and close the flow of purified water to be distributed. Preferably, the distribution section (109) optionally discloses a filtering element (109a) as defined above. The water purification system (100) also includes a recycling line (R) through which water can be circulated upstream from the distribution section (109) to a location between the water inlet (101) and the pump (102), i.e., downstream of the water inlet (101) and upstream of the pump (102). Recycling purified water through the recycling line (R) and the water purification flow plays a role in maintaining the high purity of the already purified water in the water purification system (100) when purified water is not being distributed.

[0041] The combination of the distribution valve (109b) and valve (110) makes it possible to control the flow of purified water. By keeping valve (110) in the recycling line (R) closed and opening the distribution valve (109b) included in the distribution section (109), it is possible to distribute purified water from the distribution section (109). On the other hand, by closing the distribution valve (109b) and opening valve (110), it is possible for water to pass into the recycling line (R). The water then passes through the recycling line (R) and returns to a location between the water inlet (101) and the pump (102), that is, downstream of the water inlet (101) and upstream of the pump (102). From there, the water can then pass through the water purification flow.

[0042] Furthermore, as shown in Figure 1, the water purification system (100) includes a two-way or three-way valve (111) and a connection line C1 that liquidally connects the two-way or three-way valve (111) to the water purification flow at a location downstream of the first purification stage (103) and upstream of the second purification stage (104). The two-way or three-way valve (111) allows the water flow to be directed along the water purification flow, i.e., to the first purification stage (103), or through the connection line C1, thereby bypassing the first purification stage (103).

[0043] Figure 2 shows a schematic example of another preferred water purification system (100) as defined herein, but differs from one of those in Figure 1 in that the two-way or three-way valve (111) of the water purification system (100) in Figure 1 is replaced by a system of two valves (111a, 111b) that work in conjunction to direct the water flow either along the water purification flow, i.e., to or through the first purification stage (103), or along the connection line C1, thereby bypassing the first purification stage (103). Thus, opening valve (111a) and closing valve (111b) directs the water flow to the first purification stage (103). Conversely, closing valve (111a) and opening valve (111b) bypasses the first purification stage (103) by directing the water flow along the connection line C1 directly to the second purification stage (104). Valve (111a) may be, for example, a two-way valve. The valve (111b) may be, for example, a two-way valve or a check valve.

[0044] Figure 3 shows a schematic example of another water purification system (100) as defined herein, which, compared to the water purification system (100) in Figure 1, includes a connection line C2, the connection line C2 includes a two-way or three-way valve (111) and a circulation pump (112) instead of connection line C1. Optionally, the water purification system (100) shown in Figure 3 may include a valve between the branching point of the connection line C2 and the recycling line (R) and the point where the recycling line (R) returns to the water purification flow downstream of the water inlet (101) and upstream of the pump (102). Preferably, the connection line C2 is connected to the recycle line (R) at a point between the valve (110) and the location between the water inlet (101) and the pump (102), or alternatively, if the water purification system (100) depicted in Figure 3 has a valve between the branching point of the connection line C2 and the recycle line (R) and the point where the recycle line (R) returns to the water purification flow downstream of the water inlet (101) and upstream of the pump (102), the connection line C2 is connected to the recycle line (R) at a point between the valve (110) and such an optional valve. Starting the circulation pump (112) and stopping the pump (102) would divert the water flow from the recycling line (R) into the connection line C2, as performed in measurement mode, and then supply it to the water purification flow downstream of the first purification stage (103) and upstream of the second purification stage (104), thereby bypassing the first purification stage.

[0045] Figure 4 schematically illustrates a preferred water distribution section (109) with an optional conductivity cell (108), a valve (110), and a portion of a recycling line (R). Such a preferred distribution system (109) preferably includes a distribution flow and a recycling flow. The distribution flow preferably includes, and more preferably consists of, a flow meter (109c), a line (109f), a distribution valve (109b), and a filtration element (109a) adapted to allow measurement of the volume of water being distributed in sequence, and allowing removal of contaminants from the water being distributed as discussed above. The recycling flow is preferably connected to the distribution flow via a connecting line (109e) and / or line (109f). The recycling flow preferably includes, and more preferably consists of, a check valve (109d) and an outlet (109h) connected in sequence to a recycling line (R) upstream of the valve (110). Furthermore, the distribution flow of the distribution section (109) is connected to the recycling flow of the distribution section (109) at a location downstream of the line (109f) and upstream of the check valve (109d), from a position downstream of the line (109f) and upstream of the check valve (109d).

[0046] When the water purification system is in distribution mode, purified water exits the polisher (107), passes through an optional conductivity cell (108), then enters the distribution section (109) through the distribution section inlet (109g), passes through the flow meter (109c) and line (109f), and is distributed via the distribution valve (109b) and filter element (109a). When the water purification system is in measurement and recycling mode, purified water exits the polisher (107), passes through an optional conductivity cell (108), enters the distribution section (109) through the distribution section inlet (109g), and is recycled to the recycling line (R) via the connecting line (109e) and / or line (109f), check valve (109d), and outlet (109h). Thus, the recycling flow may sequentially include the following parts of the distribution section (109): the distribution section inlet (109g), and then recycled via the connecting line (109e) and / or line (109f), check valve (109d), and outlet (109h).

[0047] Figures 5a, 5b, and 5c illustrate schematic examples of water flow in the water purification system (100) of Figure 1 in the distribution, measurement, and recycling modes, respectively. Note that the distribution section (109), particularly the portion of the distribution section (109) that forms part of the recycling flow described herein, is not shown in detail in Figures 5a, 5b, and 5c. Figure 5a shows a schematic example of the water flow in the water purification system (100) of Figure 1 in distribution mode. Water is supplied to the water purification system (100) via the water inlet (101), and from there the water sequentially passes through the first purification stage (103), the ultraviolet irradiation treatment stage (105), the device for determining the total organic carbon content (106), the polisher (107), and an optional conductivity cell (108), and then into the distribution section (109), from where the purified water is distributed.

[0048] Once distribution is complete, the water purification system (100) in Figure 1 switches (manually or automatically) to the measurement mode shown in Figure 5b by opening valve (110) and closing distribution valve (109b), and water flows through pump (102), two-way or three-way valve (111), connection line C1 (which bypasses the first purification stage (103)), ultraviolet irradiation treatment stage (105), device for determining total organic matter content (106), polisher (107), optional further conductivity cell (108), and then is recycled through recycling line (R) to a location upstream of pump (102) and downstream of water inlet (101), with valve (110) open and valve (109b) closed.

[0049] In measurement mode, the total organic carbon content of the purified water is determined by a device (106) that determines the total organic carbon content. Following the determination of the total organic carbon content, the water purification system (100) in Figure 1 is preferably switched (manually or automatically) to the recycling mode shown in Figure 5c, where the water in the water purification system (100) follows essentially the same flow as in the distribution mode shown in Figure 5a, but instead of being distributed via the distribution section (109), the purified water is recycled via the recycling line (R) to the starting point of the water purification flow, i.e., downstream of the water inlet (101) and upstream of the pump (102). In the water purification system of Figure 2, the water flow in the distribution, measurement, and recycling modes is essentially similar to that of the purification system (100) in Figure 1, the only difference being that for the measurement mode, the water flow is controlled to bypass the first purification stage by closing valve (111a) and opening valve (111b), rather than by using a two-way or three-way valve (111).

[0050] Similarly, Figures 6a, 6b, and 6c show schematic examples of the water flow in the water purification system (100) of Figure 3 in the distribution, measurement, and recycling modes, respectively. Note that the distribution section (109), particularly the portion of the distribution section (109) that forms part of the recycling flow described above, is not shown in detail in Figures 6a, 6b, and 6c. Figure 6a shows a schematic example of the water flow in the water purification system (100) of Figure 3 in distribution mode. Water is supplied to the water purification system (100) via the water inlet (101), from where it sequentially enters the purification stage (103), the ultraviolet irradiation treatment stage (105), the device for determining the total organic carbon content (106), the polisher (107), the optional conductivity cell (108), and then the distribution section (109), from where the purified water is distributed.

[0051] Once distribution is complete, the water purification system (100) in Figure 3 switches to measurement mode (manually or automatically) as shown in Figure 6b by opening a valve (110) and closing a distribution valve (109b), where water flows through the distribution section (109), through the (opened) valve (110) and the recycling line (R), through the connection line C2 including the circulation pump (112) (thus bypassing the first purification stage (103)), through the ultraviolet irradiation treatment stage (105), through the device (106) for determining the total organic carbon content, and through an optional conductivity cell (108) back to the distribution section (109). In measurement mode, the total organic carbon content is measured using device (106) to determine the total organic carbon content of the purified water.

[0052] Following the determination of the total organic carbon content, the water purification system (100) in Figure 3 is preferably switched (manually or automatically) to the recycling mode shown in Figure 6c, where the water in the water purification system (100) follows essentially the same flow as in the distribution mode shown in Figure 6a, but instead of being distributed through the distribution section (109), the purified water is recycled through the recycling line (R) to the starting point of the water purification flow, i.e., downstream of the water inlet (101) and upstream of the pump (102).

[0053] example The following examples are intended to illustrate, in a non-limiting manner, the mechanisms and advantages of current water purification systems and their operating processes.

[0054] Example 1. Water purification systems schematically shown in Figure 1 or 2, both available from Merch KGaA (Darmstadt, Germany), equipped with a Q-Gard® T1 purification cartridge in the first purification stage and a Quantum® TEX polishing cartridge in the second purification stage, were idled over the weekend and then restarted using the feedwater from the reverse osmosis purification stage. As shown in Figure 7, immediately after restarting, a sharp increase in the total organic carbon level in the purified water coming out of the first purification stage (see the continuous line labeled "TOC Step A") was registered by device (106), but each control measurement of the distributed water still showed that the total organic carbon content was well within specifications (see the dashed line labeled "TOC Use Point"). These results suggest that relying solely on the total organic carbon content determined after the first purification stage can lead to false alarms, i.e., indications that the distribution water does not meet purity requirements, even though it is actually responding.

[0055] Example 2. A new purification cartridge was installed in the water purification system of Example 1, and it was operated alternately in distribution mode and measurement mode until both the first and second purification stages were exhausted. The curves for the resistivity measured by device (106) to determine the total organic content of the water purification flow in device (106) are shown in Figure 8. "AR" is displayed for the purified water after passing through the first purification stage, and "BR" is displayed for the purified water at the point of use, i.e., in the distribution section. "AT" is displayed for the total organic carbon content of the purification flow, and "BT" is displayed for the purified water at the point of use. The graph in Figure 8 clearly shows that the total organic carbon content of the water purification flow in device (106) is generally higher than the actual value at the point of use, and further, as shown by the curves BR and BT, the first and second purification stages together were able to supply purified water of the required purity even after the performance of the first purification stage began to degrade, as shown by the curves AR and AT. It can even be seen that the second purification stage alone was able to produce purified water of the desired purity for a period of time after the first purification stage had been completely depleted. This water purification system can separately assess the performance of the first purification stage, so the user is warned at the appropriate time to prepare for the replacement of the first purification stage, and then again when it is time to prepare for the replacement of the second purification stage. This effectively allows the user to further extend the lifespan of the purification cartridges used in the purification stages without risking being unable to produce purified water of the desired purity.

[0056] Example 3. For the water purification system in Example 1, the total organic carbon content was determined by obtaining the "intermediate TOC content" using device (106) in distribution mode and the "TOC at the point of use" using device (106) in measurement mode. The comparative values ​​were obtained using two reference calibration TOC monitors; the first one draws water immediately downstream of the first purification stage and therefore reflects the "intermediate TOC content," and the second one draws water downstream of the polisher and therefore reflects the "TOC at the point of use." The results of this comparison under various conditions are shown in Table 1 below, where the values ​​of "TOC at the point of use" and "TOC at the comparison point of use" are as follows: -Examples 3.1 and 3.2, immediately after replacing the purification cartridge and flushing with 20 liters of water, -Examples 3.3, 3.4, and 3.5, during normal operation after running the water purification system in measurement mode for 3 minutes, and -Examples 3.6 and 3.7, during normal operation after running the water purification system in measurement mode for 10 minutes. This was obtained. [Table 1] The above data clearly demonstrates that this water purification system obtains reliable values ​​for the total organic carbon content during the purification flow, particularly at the point of use.

[0057] Example 4. Example 2 was repeated, however, using an IPAK Meta® polishing module for the first purification stage and an IPAK Quanta® polishing cartridge for the second purification stage, both of which are available from Merck KGaA (Darmstadt, Germany). The results for each are shown in Figure 9, where "AR" indicates the resistivity measured by device (106), "AT" displays the associated total organic carbon content, "BR" displays the resistivity measured at the use point, and "BT" displays the associated total organic carbon content. The curves in Figure 9 support the findings of Example 2. Overall, the inventors have found, to their great surprise, that the water purification system and the process of operating it generally provide a value of total organic carbon content at the point of use that reflects the distributed water, far better than the aforementioned water purification systems and methods.

[0058] Furthermore, the water purification system and the process for operating such a system benefit from certain limitations of water purification systems as defined herein, namely, that the first and second purification stages are generally "symmetrical," that is, essentially the same size, generally equivalent, and essentially the same processing capacity. Thus, the water purification system and its operating process make it possible to specifically distinguish between the exhaustion of the first purification stage, i.e., when the first purification stage no longer purges contaminants to the desired extent, and the exhaustion of the second purification stage, i.e., when the second purification stage no longer purges contaminants to the desired extent. When the first purification stage is exhausted, the second purification stage can still purify water to the desired purity, thereby enabling the distribution of purified water of the desired purity. Thus, the water purification system and its operating process also make it possible to better and more accurately determine when a purification stage needs to be replaced. This not only reduces operating costs but also reduces waste from unnecessarily replaced purification stage hardware, such as purification cartridges. Therefore, this water purification system and the process for such operation make it possible to overcome at least two drawbacks of the prior art.

[0059] Furthermore, this water purification system demonstrates remarkable versatility and capability when evaluating and determining the individual effectiveness of the first and second purification stages. For example, the effectiveness of the first purification stage can be determined by first operating the water purification system in distribution mode (see, for example, Figures 5a and 6a), and then switching to measurement mode (see, for example, Figures 5b and 6b). Determining the conductivity, and thereby the total organic carbon content, first in distribution mode and then in measurement mode will indicate to the user whether the first purification stage is still functioning correctly and not exhausted. In other words, if the values ​​in distribution mode and measurement mode do not differ significantly, the first purification stage is functioning normally. On the other hand, if the values ​​in distribution mode and measurement mode differ significantly, especially if the value in distribution mode is significantly higher than the value in measurement mode, the first purification stage is not functioning normally and, as a result, needs to be replaced.

[0060] Furthermore, this water purification system, which includes a connecting line (e.g., represented by line C1 in Figures 1 and 2) that liquidally connects the water purification flow from a branching point located downstream of the pump and upstream of the first purification stage to a location downstream of the first purification stage and upstream of the second purification stage, makes it possible to determine the purity of the feedwater reaching the water purification flow through the inlet. This may be done by first passing the water directly from the inlet through the pump and line C1 to the second purification stage, where the first conductivity and consequently the first total organic matter content are determined. The water purification system is then switched to measurement mode to determine the second conductivity and consequently the second total organic matter content. Comparing the first and second values ​​will reveal the water quality of the feedwater reaching the inlet.

[0061] In summary, this water purification system enables the determination of the total organic carbon content of distributed purified water with good accuracy and reliability, while simultaneously simplifying the overall water purification system by utilizing and dual-using functions already present in the water purification stream.

Claims

1. A water purification system (100), which is described below, (a) A purification stage (104) comprising, in order, an ultraviolet irradiation step (105) and a polisher (107), or essentially consisting thereof; and (b) A device (106) located downstream of the ultraviolet irradiation step (105) and upstream of the polisher (107) for measuring the total organic carbon content. (c) Measurement loop, Includes, The measurement loop includes the purification stage (104) and a device (106) for measuring total organic carbon. The water purification system (100) is as follows: (a') Water inlet (101) and; (b') Water purification flow, in order as follows: (b1') Pump (102) and; (b2') The first purification stage (103) that purifies the water to the first water purity grade; (b3') A second purification stage (104) comprising, in order, the ultraviolet irradiation step (105) and the polisher (107), or the polisher (107), for purifying the water to a second water purity grade higher than the first water purity grade; and (b4') Distribution section (109) and; The water purification flow including; and (c') A recycling line (R) that liquidally connects the water purification flow from a position downstream of the distribution section (109) to a position downstream of the water inlet (101) and upstream of the pump (102); Includes, Here, the water purification flow and / or recycling line (R) is adapted to allow bypassing the first purification stage (103), thereby establishing a measurement loop, and Here, the water purification system includes a conductivity cell (108) located downstream of the polisher (107) and upstream of the distribution section (109), The aforementioned water purification system (100).

2. The water purification system (100) according to claim 1, wherein the water purification system (100) includes a connecting line C1 that liquidally connects the water purification flow from a branching point located downstream of the pump and upstream of the first purification stage to a location downstream of the first purification stage and upstream of the second purification stage, and the water flow through the connecting line can bypass the first purification stage.

3. The water purification system (100) includes a two-way valve or a three-way valve at the branching point; or The water purification system (100) includes a first valve located in the water purification flow downstream of the branching point and upstream of the first purification stage, and a second valve located in the connecting line C1. The water purification system (100) according to claim 2.

4. The water purification system (100) according to any one of claims 1 to 3, wherein the water purification system (100) includes a connecting line C2 that liquidally connects a recycling line (R) to the water purification flow at a position downstream of the first purification stage and upstream of the second purification stage, and the connecting line C2 includes a circulation pump.

5. The water purification system according to any one of claims 1 to 4, wherein the first purification stage includes one or more purification media selected from the group consisting of a cation ion exchanger, anion ion exchanger, and activated carbon.

6. The water purification system according to any one of claims 1 to 5, wherein the ultraviolet irradiation treatment device includes an ultraviolet irradiation source that emits radiation having a wavelength in the range of at least 150 nm, and such ultraviolet irradiation source is selected from the group consisting of a low-pressure mercury lamp, a cold cathode mercury lamp, and an excimer lamp.

7. The water purification system according to any one of claims 1 to 6, wherein the polisher includes one or more selected from the group consisting of activated carbon, a cation ion exchanger, and an anion ion exchanger.

8. An operating process for a water purification system (100), wherein the water purification system (100) is as follows: (a) A purification stage (104) comprising, in order, an ultraviolet irradiation step (105) and a polisher (107), or essentially consisting thereof; and (b) A device (106) located downstream of the ultraviolet irradiation step (105) and upstream of the polisher (107) for determining the total organic carbon content. (c) Measurement loop, Includes, The measurement loop includes the purification stage (104) and a device (106) for determining total organic carbon. The process here involves the following steps: (1) Passing water through the purification stage (104) to obtain purified water; and (2) Determining the total organic carbon content contained in the purified water by passing the purified water through the measurement loop and using the device (106). Includes, The water purification system (100) (a') Water inlet (101) and; (b') Water purification flow, in order as follows: (b1') Pump (102) and; (b2') The first purification stage (103) that purifies the water to the first water purity grade; (b3') A second purification stage (104) comprising, in sequence, an ultraviolet irradiation step (105) and a polisher (107) for purifying the water to a second water quality grade higher than the first water quality grade; and (b4') Distribution section (109) and; The water purification flow including; and (c') A recycling line (R) that liquidally connects the water purification flow from a position downstream of the distribution section (109) to a position downstream of the water inlet (101) and upstream of the pump (102); Includes, Here, the water purification system includes a conductivity cell (108) located downstream of the polisher (107) and upstream of the distribution section (109), The above process is as follows: (1') Providing water through the water inlet (101); (2') Pass water through a water purification flow to obtain purified water; (3') Distributing the purified water obtained in step (2'); and (4') The method includes determining the level of total organic compounds by bypassing the first purification stage (103) and passing the purified water through a measurement loop, and determining the total organic carbon content by a device (106) that measures total organic carbon. The aforementioned process.

9. A process for operating the water purification system (100) according to claim 8, wherein the water purification system (100) includes a connection line C1 that liquidally connects the water purification flow from a branch point located downstream of the pump (102) and upstream of the first purification stage (103) to a location downstream of the first purification stage (103) and upstream of the second purification stage (104), and the water flow through the connection line C1 can bypass the first purification stage (103). In step (4'), the first purification stage (103) is bypassed by blocking the water purification flow downstream of the branching point and upstream of the first purification stage (103), allowing water to pass through the connecting line C1 to the second purification stage (104). The aforementioned process.

10. A process for operating the water purification system (100) according to claim 9, wherein the water purification system (100) is at a branching point (i) Two-way valve or three-way valve (111), or (ii) A first valve (111a) located downstream of the branching point and upstream of the first purification stage (103) in the water purification flow, and a second valve (111b) located in the connecting line C1, The process including the process described above.

11. A process for operating the water purification system (100) according to claim 8, wherein the water purification system (100) includes a connection line C2 that liquidally connects the recycling line (R) to the water purification flow at a position downstream of the first purification stage (103) and upstream of the second purification stage (104), and The connection line C2 includes a circulation pump (112), In step (4'), the first purification stage (103) is bypassed by forcibly passing water through the connection line C2. The aforementioned process.

12. A process for operating a water purification system (100) according to any one of claims 8 to 11, the process comprising, if present, one or more selected from the group consisting of a first purification stage (103) as defined in claim 5, a second purification stage (104) as defined in claim 6, and a polisher (107) as defined in claim 7.

13. A process for operating a water purification system (100) according to any one of claims 8 to 11, the process comprising the step of recycling the purified water by passing the purified water sequentially through the water purification flow and the recycling line (R) following step (4').

Images