SYSTEM AND METHOD FOR STERILIZING A FLUID

Abstract

System and method for sterilizing a fluid. The system comprises a UV emitter (1) surrounded by an elongated element (2) arranged concentrically with respect to the UV emitter through which a coolant fluid cooling the UV emitter circulates, the elongated element (2) being surrounded by an elongated element (3) arranged concentrically with respect to the UV emitter through which the fluid to be sterilized circulates, the elongated element being (3) surrounded by an elongated element (4) arranged concentrically with respect to the UV emitter through which a coolant or heating fluid cooling or heating the fluid to be sterilized circulates. In the method for sterilizing a fluid, the fluid to be sterilized is subjected to UV radiation at a temperature ranging between 20 C. and 160 C.

Claims

1. A system for sterilizing a fluid, comprising a UV emitter surrounded by an elongated element, arranged concentrically with respect to the UV emitter, through which a coolant fluid cooling the UV emitter circulates, the elongated element being surrounded by an elongated element, arranged concentrically with respect to the UV emitter, through which the fluid to be sterilized circulates, the elongated element being surrounded by an elongated element, arranged concentrically with respect to the UV emitter, through which a coolant or heating fluid cooling or heating the fluid to be sterilized circulates.

2. The system according to claim 1, wherein the elongated element through which the fluid to be sterilized circulates has coarse walls or spiral pathways.

3. The system according to claim 1, wherein the fluid to be sterilized is selected from the group consisting of a food, a cosmetic, a drug, a pharmaceutical composition, a hospital fluid, a scent, a perfume and a chemical compound.

4. The system according to claim 1, wherein the UV emitter emits at a wave length of between 200 and 312 nm.

5. The system according to the claim 1, wherein the distance between the external wall of the elongated element and the internal wall of the elongated element is between 0.5 and 5 mm.

6. The system according to claim 1, wherein two or more systems may be coupled together in series or in parallel.

7. The system according to claim 6, wherein one of the systems has a UV emitter that emits at a wave length of between 290 and 320 nm.

8. The system according to claim 1, wherein it comprises devices for measuring and controlling the emission irradiance of the UV emitter.

9. The system according to claim 1, wherein it comprises devices for measuring and controlling the temperatures.

10. A method for the sterilization of a fluid, wherein it is carried out in a system comprising a UV emitter surrounded by an elongated element arranged concentrically with respect to the UV emitter through which a coolant fluid cooling the UV emitter circulates, the elongated element being surrounded by an elongated element arranged concentrically with respect to the UV emitter through which the fluid to be sterilized circulates, the elongated element being surrounded by an elongated element arranged concentrically with respect to the UV emitter through which a coolant or heating fluid cooling or heating the fluid to be sterilized circulates, and in that it comprises subjecting the fluid to be sterilized to UV radiation at a temperature ranging between 20 C. and 160 C.

11. The method according to claim 10, wherein the temperature ranges between 2 and 80 C.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0048] FIG. 1. Shows an external side view of the system of the invention, wherein it is possible to observe the arrangement of the inlet and outlet points of the various fluid circuits: inlet (5) and outlet (6) of the fluid to be sterilized, inlet (7) and outlet (8) of the coolant or heating fluid, air inlet (9) and outlet (10).

[0049] FIG. 2. Shows a longitudinal section of the system of the invention, wherein it is possible to observe the arrangement of the various chambers through which the various fluids circulate, as well as the arrangement of the UV emitter.

[0050] FIG. 3. Shows an enlarged view of the longitudinal section, wherein it is possible to observe in greater detail the arrangement of the chambers through which the various fluids circulate: air (2), fluid to be sterilized (3), coolant or heating liquid (4), UV emitter (1). It is also possible to observe the arrangement of the gaskets or seals (11, 12, 13) that provide air-tightness between the emitter, the quartz cover and the chamber through which the product circulates.

PREFERRED EMBODIMENTS

Example 1. Effect of UVC Light Treatment on Lethality in Different Microorganisms

[0051] By way of example to demonstrate the effectiveness of the present invention, various microorganisms having different levels of sensitivity to UVC treatment were studied in an aqueous solution having a low absorbance coefficient (0.43 cm.sup.1) and in liquid egg white having a high absorbance coefficient (107 cm.sup.1), at different temperatures, 20 and 50 C. in the treatment with inoculated aqueous solutions and at 20 and 55 C. in the treatments with inoculated liquid egg whites. The concentration of microorganisms in the control samples amounted to approximately 10.sup.6-10.sup.7 cfu/ml. To calculate the dose received (Equation 1), it was necessary to calculate the transmitted Irradiance (I) by means of the Beer-Lambert Law (Equation 2) taking into account the thickness of the fluid, path length (for the aqueous solution and liquid egg white), which was 1 mm (d=0.1 cm), the absorbance coefficients for X=254 nm (described above) and incident Irradiance (I.sub.0=31 mW/cm.sup.2). The microbiological results in Tables 1-3 are expressed as lethality (Equation 3).

Dose=Irradiance.Math.Time(Equation 1)

[0052] In Equation 1, Dose is expressed in mW.Math.S/cm.sup.2, Irradiance is expressed in mW/cm.sup.2 and Time is expressed in seconds.

I=I.sub.0.Math.10.sup.d(Equation 2)

[0053] In Equation 2, I is transmitted Irradiance, I.sub.0 is incident Irradiance, is Absorbance coefficient and d is path length.

Lethality=Log.sub.10(N.sub.0/N)(Equation 3)

[0054] In Equation 3, N.sub.0 is the initial cfu/cm.sup.2 number before the treatment and N is the cfu/cm.sup.2 number after the treatment.

TABLE-US-00001 TABLE 1 Effect of UVC light treatment with an irradiance of 31 mW/cm.sup.2 at 20 C. for different exposure times on the lethality of different microorganisms in an aqueous solution (Absorbance coefficient: 0.43 cm.sup.1). Data from three independent experiments with duplicated quantification of the results of every experiment (n = 6). The average standard deviation is shown. Lethality is expressed in cfu/cm.sup.2. Exposure time (seconds) 3 s 6 s 12 s 18 s 24 s 30 s A. niger 0.47 0.27 1.12 0.15 2.04 0.05 3.58 0.04 4.15 0.17 5.1 (spores) B. subtilis 1.53 0.55 2.9 0.31 4.88 0.31 5.91 0.23 6.5 (spores) S. aureus 3.43 0.13 5.43 0.64 6.7 E. coli 4.83 0.24 5.79 0.96 6.9 L. innocua 3.28 0.28 4.93 0.65 6.8 M. luteus 2.53 0.21 5.32 0.71 6.5 P. fluorescens 2.71 0.25 4.75 0.53 7.1

TABLE-US-00002 TABLE 2 Effect of UVC light treatment with an irradiance of 31 mW/cm.sup.2 at 50 C. for different exposure times on the lethality of different microorganisms in an aqueous solution (Absorbance coefficient: 0.43 cm.sup.1). Data from three independent experiments with duplicated quantification of the results of every experiment (n = 6). The average standard deviation is shown. Lethality is expressed in cfu/cm.sup.2. Exposure time (seconds) 3 s 6 s 12 s 18 s 24 s 30 s A. niger 0.43 0.31 1.25 0.13 2.28 0.08 3.82 0.21 4.86 0.08 5.1 (spores) B. subtilis 1.31 0.44 2.94 0.38 4.82 0.44 6.01 0.33 6.5 (spores) S. aureus 3.17 0.15 6.33 0.45 6.7 E. coli 4.16 0.22 6.9 L. innocua 3.07 0.21 5.94 0.75 6.8 M. luteus 2.88 0.36 5.14 0.89 6.5 P. fluorescens 3.58 0.34 6.34 0.44 7.1

TABLE-US-00003 TABLE 3 Effect of UVC light treatment with an irradiance of 31 mW/cm.sup.2 for different exposure times on the lethality of different microorganisms in liquid egg white (Absorbance coefficient: 107 cm.sup.1). Data from three independent experiments with duplicated quantification of the results of every experiment (n = 6). The average standard deviation is shown. Lethality is expressed in cfu/cm.sup.2. Exposure time (seconds) 3 s 6 s 12 s 18 s 24 s 30 s 20 C. B. subtilis 0.21 0.18 0.51 0.21 1.12 0.28 1.74 0.12 2.4 0.42 3.1 0.54 (spores) M. luteus 0.5 0.21 1.04 0.33 1.96 0.24 3.15 0.23 4.01 0.33 5.3 0.64 E. coli 1.01 0.61 1.62 0.15 3.21 0.33 5.02 0.31 6.3 0.25 6.4 55 C. B. subtilis 0.19 0.26 0.6 0.63 0.98 0.15 1.8 0.41 2.51 0.5 2.95 0.58 (spores) M. luteus 0.66 0.07 1.14 0.21 2.14 0.2 3.71 0.05 4.68 0.18 6.1 0.15 E. coli 1.2 0.23 1.88 0.24 3.55 0.54 5.88 0.33 6.4

[0055] Starting from the data expressed in the above tables (Table 1-3) it has been observed that lethality increases linearly and proportionally at longer exposure times, at least in the time ranges which have been tested.

[0056] When an Irradiance of 31 mW/cm.sup.2 was applied, at 20 C. in aqueous solutions having a low absorbance coefficient (0.43 cm.sup.1) and times were between 3 and 6 seconds, lethality levels (reductions) of between 2.5-5.8 Logarithmic units (Log) were reached in vegetative bacteria, whereas the more ultraviolet-resistant microorganisms (B. subtilis spores and A. niger spores) reached reductions of 0.5-3 Log.

[0057] When an Irradiance of 31 mW/cm.sup.2 was applied, at 20 C. in fluids having a high absorbance coefficient (107 cm.sup.1), such as liquid egg white, and times were between 6 and 18 seconds, the reductions were 1.6-5, 1-3 and 0.5-1.7 Log for the vegetative bacteria (E. coli and M. luteus) and B. subtilis spores, respectively.

[0058] When an irradiance of 31 mW/cm.sup.2 was applied, at 50 C. in aqueous solutions having a low absorbance coefficient (0.43 cm.sup.1), and times were between 3 and 6 seconds, lethality levels (reductions) of between 3 and >6.9 Log were reached in vegetative bacteria, whereas in the sporulated microorganisms (B. subtilis spores and A. niger spores) reductions of 0.4-3 Log were achieved, nearly the same as when room temperature was applied (20 C.).

[0059] However, when an Irradiance of 31 mW/cm.sup.2 was applied, at 55 C. in fluids having a high absorbance coefficient (107 cm.sup.1), such as liquid egg white, and times were between 6 and 18 seconds, the reductions were 2-6, 1-3.7 and 0.6-1.8 Log for the vegetative bacteria (E. coli and M. luteus) and B. subtilis spores, respectively.

[0060] Furthermore, the liquid egg white (LEW) samples treated with or without UVC and/or temperature, never coagulated and conserved the main functional characteristics (colour, odour, viscosity, foaming capacity, etc.).