System for treating a fluid with non-mercury-based UV light

Abstract

The present invention generally relates to a system for treating a fluid and specifically to a treatment system configured for improved bacterial reduction, wherein the system comprises a field emission based UV light source adapted to emit light within a ultraviolet C (UVC) spectrum with a wavelength range having an upper range limit being higher compared to light emitted from a mercury based UV light source.

Claims

1. A system for treating a fluid, comprising: a container arranged to receive an amount of a fluid; at least two different UV light sources contained within the container, the at least two different UV light sources comprising a first UV light source and a second UV light source different from the first UV light source, the first UV light source being a non-mercury field emission based UV light source and the second UV light source being a mercury based UV light source; and an electrical power supply operatively associated with the at least two different UV light sources, the electrical power supply arranged to provide electrical power to the first and second UV light sources for treating the amount of the fluid received within the chamber using the first and second UV light sources, wherein the first UV light source is adapted to emit both (i) light within the ultraviolet C (UVC) spectrum with a wavelength range having an upper range limit being higher compared to light emitted from the mercury based second UV light source, and (ii) radiation within a wavelength range between 320 nm and 400 nm, wherein the second UV light source is configured to emit radiation at around 254 nm, wherein the field emission based UV light source comprises a light converting material arranged to receive electrons and to emit UV light, and wherein the light converting material is selected to be at least one of LaPO.sub.4:Pr.sup.3+, LuPO.sub.3:Pr.sup.3+, Lu.sub.2Si.sub.2O.sub.7:Pr.sup.3+, YBO.sub.3:Pr.sup.3+, or YPO.sub.4:Bi.sup.3+ in order to improve a deactivation curve for a selected microorganism.

2. The system according to claim 1, wherein the first UV light source is configured to emit radiation within a wavelength range between 240 nm and 320 nm.

3. The system according to claim 1, wherein the light converting material is a phosphor material.

4. The system according to claim 1, wherein the first UV light source further comprises at least one UVC Light Emitting Diode (LED).

5. The system according to claim 1, wherein the second UV light source comprises a Low-Pressure HG-lamp.

6. The system according to claim 1, wherein the electrical power supply is configured to selectively activate the first UV light source based on a predetermined condition.

7. The system according to claim 1, wherein the first and the second UV light source are activated essentially simultaneously.

8. The system according to claim 6, wherein the predetermined condition is a predetermined disinfection requirement for the fluid treated by the system.

9. The system according to claim 1, further comprising a sensor for measuring a UV intensity level within the container.

10. The system according to claim 1, wherein at least one of the first and the second UV light source at least partially extends into the amount of the fluid received within the container.

11. The system according to claim 1, wherein the container is divided in a first and a second portion, the first portion holding the first UV light source and the second portion holding the second UV light source.

12. The system according to claim 8, further comprising a control unit in communication with the sensor and configured for controlling the selective activation of the first and the second UV light source.

13. The system according to claim 1, wherein the first UV light source is configured to emit radiation at around 265 nm.

14. The system according to claim 1, wherein the electrical power supply is configured to selectively activate the first and second UV light sources based on a predetermined condition, wherein the predetermined condition is a sampled bacteria level of the fluid.

15. The system according to claim 1, further comprising a sensor for measuring a UV intensity level within the container, wherein the electrical power supply is configured to selectively activate the first and second UV light sources based on a predetermined condition, wherein the predetermined condition is the UV intensity level measured by the sensor.

16. The system according to claim 6, wherein the predetermined condition is a sampled bacteria level of the fluid.

17. The system according to claim 6, further comprising a sensor for measuring a UV intensity level within the container, wherein the predetermined condition is the UV intensity level measured by the sensor.

18. A system for treating a fluid, comprising: a container arranged to receive an amount of a fluid; at least two different UV light sources contained within the container, the at least two different UV light sources comprising a first UV light source and a second UV light source different from the first UV light source, the first UV light source being a non-mercury field emission based UV light source and the second UV light source being a mercury based UV light source; and an electrical power supply operatively associated with the at least two different UV light sources, the electrical power supply arranged to provide electrical power to the first and second UV light sources for treating the amount of the fluid received within the chamber using the first and second UV light sources, wherein the first UV light source is adapted to emit both (i) light within the ultraviolet C (UVC) spectrum with a wavelength range having an upper range limit being higher compared to light emitted from the mercury based second UV light source, and (ii) radiation within a wavelength range between 320 nm and 400 nm, wherein the second UV light source is configured to emit radiation at around 254 nm, wherein the non-mercury field emission based UV light source comprises a light converting material arranged to receive electrons and to emit UV light, the light converting material being selected to improve a deactivation curve for a selected microorganism, and wherein the electrical power supply is configured to selectively activate the first and second UV light sources based on a predetermined condition, wherein the predetermined condition is a sampled bacteria level of the fluid.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The various aspects of the invention, including its particular features and advantages, will be readily understood from the following detailed description and the accompanying drawings, in which:

(2) FIG. 1 shows an example of a prior-art fluid treatment system,

(3) FIG. 2 provides an exemplary embodiment of the inventive system for treating a fluid,

(4) FIG. 3 illustrates an alternative embodiment of the inventive system for treating a fluid,

(5) FIGS. 4a-b illustrates the emission spectra from an Hg light source and its corresponding germicidal de-activation curve, and

(6) FIGS. 5a-f illustrate different emission spectra resulting from different phosphor material and their corresponding germicidal de-activation curves.

DETAILED DESCRIPTION

(7) The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which currently preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness, and fully convey the scope of the invention to the skilled addressee. Like reference characters refer to like elements throughout.

(8) Other applications such as air disinfection, surface disinfection, etc., are equally possible and the system implementations described are generally equally valid. It is also obvious to the skilled person that scaling and different combinations of the described implementations are straightforward. As an example, the figures are showing light sources of similar size and shape for practical reasons, but they may in fact have completely different sizes as well as different form factors (shapes). Furthermore, there may be additional light sources in such systems.

(9) Referring now to the drawings and to FIG. 1 in particular, there is illustrated a typical simple fluidic UV disinfection system 100 of the current state of the art is shown in cross sectional view. It should be noted that the complete system usually may contain filters of different kinds as well as other components. Here only the UV disinfection section is described.

(10) A fluid, such as water, enters the disinfection tube through the inlet 102 into a container arranged to receive an amount of the fluid. A light source 104, most commonly being a low pressure mercury (Hg) based UV light source, is turned on and energized by an electronic drive unit (ballast) 106. The light source 104 is commonly additionally protected by a UV transmitting sleeve (not shown, applicable to all embodiments) to prevent Hg to enter the water should the Hg light source break. The disinfection tube may in some embodiment comprise various structures or means to provide a turbulent flow in order to further ensure that all organisms are being subjected to an as large amount of UV radiation as possible, such structures and means also not shown. The electronic drive unit 106 is in turn connected to a power supply 108, such as a wall electrical outlet or similar. The electronic power supply may further be integrated with the disinfection tube or the light source. The water flows by the light source 104 and exits through an outlet 110. The UV intensity may be monitored by an UV sensor 112, connected to the electronic drive unit 106 which is safeguarding the system for adequate UV intensity to ensure adequate disinfection. The intensity may change for example due to different transmittance of the fluid and/or due to intensity variation of the light source. The electronic drive unit 106 may further control a variable valve (not shown), thus controlling the flow rate by using the UV intensity to determine a maximum value of the flow and thereby ensuring disinfection performance. Further sensors may comprise temperature and pressure (not shown here).

(11) A first preferred embodiment of the present invention is conceptualized in FIG. 2 and the discussion below. In this case, the two light sources 104 and 204 are integrated into a single disinfection tube/arrangement 200. Specifically, water enters the water treatment arrangement 200 through an inlet 102 here controlled by (an optional) inlet valve 206. The electronic drive unit 106, which may be using a remote control device 208 (wire bound or wireless) will turn on both the Hg light source 104 and additional UV light source 204 that exhibits no significant tailing effect as soon as the input valve 206 is open, the additional light source 204 being a non-mercury based UV light source. The electronic drive unit 106 will also open an output valve 210, ensuring that the fluid flows by both light sources 104, 204, now leaving the disinfection tube through an outlet 212. It may be advantageous to ensure short delays between for example opening the output and input valve. Again, a UV-sensor 112 may be used to monitor the UV intensity at the inner wall of the water treatment arrangement 200.

(12) Now turning to FIG. 3, showing a second preferred embodiment of a treatment system 300. This embodiment consists of two similar systems connected in series, one with the Hg light source and the other with a light source that exhibits no significant tailing effect. The order of the two can be different as compared to what is shown in FIG. 3. It should be noted that the first stage in the water disinfection is similar to what is outlined in FIG. 2 above and thus not further discussed. Water to be processed enters inlet 102, passes by the Hg light source 104, and leaves the first container through outlet 110. A conduit 304 connects the outlet 110 to an inlet 302 of a second container comprising the non-Hg light source 204. The processed water passes the second light source 204 and exits the second container through an outlet 312.

(13) Additionally, in the embodiment shown in FIG. 3 the first container comprising the first light source 104 is provided with a second outlet 314, i.e. where the water is only passing by the first light source 104, for example suitable for situations where the water may be used also when it has not reached the highest level of disinfection. In comparison, the water exiting the outlet 312 will have passed by both the first 104 and the second 204 light source, having undergone both UVC treatments and thus is highly disinfected and may for example be more suited as drinking water.

(14) The Hg light source 104 and the additional UV light source 204 that exhibits no significant tailing effect are powered by the electronics drive unit 106, which may or may not be integrated to contain drive units for both light sources (as shown) or be separated (not shown). The electronic drive unit 106 may further be partitioned in several ways, including partially or fully being integrated with e.g. the light sources 104, 204. Other possibilities for partitioning the electronic drive unit 106 are numerous and within the scope of the invention. The intensity of the additional UV light source 204 may be monitored by an additional UV sensor 310. The intensity is fed-back to the electronic drive 106 unit which may comprise the functionality for controlling the intensity of the additional UV light source 204. In all embodiments it should be noted that it is further possible to allow the user to decide if the water should be further disinfected or not, this way saving overall power consumption and lamp life. This implementation may easily be done by introducing e.g. a switch (not shown). Preferably indications of which state the system is in e.g. Light Emitting Diodes of different colors, a display, or other means may be used.

(15) Turning now to FIGS. 4a and b, 5a-f. Note that all measured de-activation curves show the relative reduction as function of UV dose in order to be comparable, thus the vertical axis shows the logarithm of the ratio between the remaining concentration of E. coli in Colony Forming Units per milliliter (CFU/ml)−denoted N−the initial concentration before irradiation, denoted N.sub.o, thus denoted log(N/No).

(16) As can be seen in FIG. 4a, a LP-Hg lamp essentially emits a strong relatively sharp peak at around 254 nm. FIG. 4b shows the corresponding deactivation of Escherichia coli (E. coli) in tap water. As can be seen, a certain level of E. coli is reached after which no further reduction is seen, i.e. the curve flattens over time at a set level.

(17) In FIGS. 5a-4f, the beneficial de-activation of E. coli of the inventive system is illustrated.

(18) In FIG. 5a, the emission spectra from an UVC field emission light source provided with a first phosphor material (light powder) for UV light emission is provided. In FIG. 5a, the phosphor material has been selected to be a LuPO.sub.3:Pr.sup.3+ phosphor material (or equivalent). In FIG. 5b, the corresponding de-activation curve is shown, for disinfection of water, where no significant tailing is visible.

(19) In FIG. 5c, a second phosphor material in the form of a Lu.sub.2Si.sub.2O.sub.7:Pr.sup.3+ phosphor material is used, and FIG. 5d shows the corresponding de-activation curve. As may be seen, in FIG. 5d, a de-activation of almost 8 orders of magnitude has been achieved, i.e. 99.999999% of the bacteria have been de-activated.

(20) Turning finally to FIGS. 5e and 5f, where a third phosphor material in the form of a LaPO.sub.4:Pr.sup.3+ phosphor material is used and the corresponding de-activation curve is shown, respectively.

(21) Furthermore, additional phosphor materials such as YBO.sub.3:Pr.sup.3+ and YPO.sub.4:Bi.sup.3+ have been evaluated with similar results.

(22) In summary, the present invention relates to a system for treating a fluid, comprising a container arranged to receive an amount of a fluid, a first UV light source contained within the container, and an electrical power supply operatively associated with the first UV light source, the electrical power supply arranged to provide electrical power to the first UV light source for treating the amount of the fluid received within the chamber using the first UV light source, wherein the first UV light source is a non-mercury based UV light source adapted to emit light within the ultraviolet C (UVC) spectrum with a wavelength range having an upper range limit being higher compared to light emitted from a mercury based UV light source.

(23) By means of the invention it is possible to further improve e.g. disinfection of the fluid by including an UV light source having a broader spectrum as compare to a prior-art treatment system where the UV radiation is solely provided to be predominately at around 254 nm. Specifically, as would be obvious from the illustrations provided in FIGS. 5a-5f, the benefits of using a non-mercury based UV light source for disinfection of bacteria comprised with e.g. water is apparent. The broader spectrum achieved with an UVC field emission light source provided with e.g. a LaPO.sub.4:Pr.sup.3+, LuPO.sub.3:Pr.sup.3+, Lu.sub.2Si.sub.2O.sub.7:Pr.sup.3+, YBO.sub.3:Pr.sup.3+ or YPO.sub.4:Bi.sup.3+ phosphor material (light powder) allows for a further bacterial reduction/deactivation, allowing for the possibility of providing a safer environment where clean water may be hard to acquire. It is equally possible to use multiple UVC-LED's with slightly different peak wavelength to achieve a similar effect.

(24) Although the figures may show a specific order of method steps, the order of the steps may differ from what is depicted. Also two or more steps may be performed concurrently or with partial concurrence. Such variation will depend on the software and hardware systems chosen and on designer choice. All such variations are within the scope of the disclosure. Likewise, software implementations could be accomplished with standard programming techniques with rule based logic and other logic to accomplish the various connection steps, processing steps, comparison steps and decision steps. Additionally, even though the invention has been described with reference to specific exemplifying embodiments thereof, many different alterations, modifications and the like will become apparent for those skilled in the art.

(25) Variations to the disclosed embodiments can be understood and effected by the skilled addressee in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. Furthermore, in the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality.