Apparatus and methods for irradiating liquids

Abstract

This invention relates to an apparatus for sterilizing, particularly flowing, liquids by means of electromagnetic radiation irradiation, and especially by means of UV radiation (UV reactor). The apparatus includes a container having an inlet for receiving the liquid and an outlet for discharging the liquid from the container. A variable or adjustable irradiation zone is provided inside the container for irradiating the liquid (26) with electromagnetic radiation, particularly UV radiation, emitted by a radiation source. In the irradiation zone, the liquid is arranged in the form of a liquid layer with a thickness H extending between the lower side of the container and expanding air bubbles above the liquid layer. By adjusting the expansion of the air bubbles within the container, for example by changing the gas pressure, thereby changing the liquid layer thickness H in the irradiation zone, effective operation of the (UV) reactor is achieved at different turbidities of the liquid. Optionally, a sensor is used to detect the penetration depth of the radiation and the layer thickness H is appropriately adjusted according to the sensor signal.

Description

Technical Field

[0001] This invention relates to an apparatus and a corresponding method for sterilizing liquids, particularly flowing liquids, by means of electromagnetic radiation and especially by means of ultraviolet radiation. The apparatus includes a container having an inlet for receiving liquid and an outlet from which the liquid can be discharged after flowing through the container. Furthermore, the apparatus includes multiple radiation sources, preferably LEDs, each designed to irradiate the flowing liquid within the interior space of the container with electromagnetic radiation, particularly electromagnetic radiation with wavelengths in the UV radiation range, preferably UV-C radiation. This apparatus is also referred to as a UV reactor. Background Technology

[0002] UV reactors can be used for a variety of purposes, such as drinking water treatment or commercial, agricultural, or domestic applications (e.g., dishwashers). Liquids other than water, such as blood or milk, can also be sterilized using this type of UV reactor.

[0003] Radiation in the wavelength range of 200 nm to 280 nm (also known as far-UV radiation or FUV radiation according to DIN 5031-7) has proven to be particularly effective. In addition, there is its adjacent range of 100 nm to 200 nm, which is correspondingly referred to as vacuum UV or VUV radiation.

[0004] In this application, the wavelength range up to 280 nm is generally referred to as UV-C radiation, the wavelength range from 280 nm to 315 nm as UV-B radiation, and the wavelength range from 315 nm to 380 nm as UV-A radiation, and these wavelength ranges are primarily used in UV reactors. For the purposes of this application, the term UV-C radiation as used herein also covers the range from 10 nm to 121 nm (extreme ultraviolet).

[0005] For effective sterilization, the radiation dose per unit volume of liquid flowing through the system in this condition (dose = intensity multiplied by time [Ws / m]) is required. 2 The radiation dose per unit volume of liquid flowing through should be a constant. However, the radiation dose per unit volume of liquid flowing through must be above a limit that ensures sterilization of the corresponding unit volume is performed as required.

[0006] Liquid media with different optical properties, especially scattering and absorption properties, have different electromagnetic radiation penetration depths due to their turbidity. If electromagnetic radiation is used to alter the properties of the medium through radiation dose, the geometry of the device, the power of the radiation source, and the radiation guidance must be adapted accordingly to the optical properties of the medium.

[0007] In turbid media, radiation intensity is strongly dependent on distance relative to the radiation source. To prevent excessive dose reduction over large distances, it is necessary to vary the flow rate with distance. Controlling the flow rate over a wide range within the reactor is difficult. Very low flow rates also increase the risk of deposition. Uniform dosing is particularly challenging in media where turbidity varies over time.

[0008] For example, turbidity in a medium can be caused by scattering or absorbing particles. These particles can be of organic or inorganic origin. Examples include dirt particles, microorganisms, algae, or suspended particles, lime particles, etc. Alternatively or additionally, turbidity can also be caused by emulsions or mixtures with other liquids (e.g., with colloidal components).

[0009] One example is a UVC reactor for water sterilization. The sterilization performance of a UV reactor is determined by its pathogen reduction coefficient RF = lg(N(t) / N0), where N0 is the initial pathogen quantity and N(t) is the amount of pathogens reduced after time t. In a wide range, pathogen reduction simplifies to the following relationship: N(t) = N0·exp(-kD(t)), where D is the dosage and k is a pathogen- and environment-specific constant.

[0010] The efficiency of UV reactors in sterilizing liquids is affected by the penetration depth of radiation within the liquid volume. Especially in the case of UV-C radiation and turbid media, the incident light intensity drops to a few percent after a few millimeters due to absorption and / or scattering. This makes it impossible to achieve the desired sterilization effect for irradiation layers several centimeters thick or thicker, or necessitates the use of very high initial light power to ensure sufficient effectiveness after attenuation. To ensure adequate sterilization, sterilization equipment in practice typically only permits the maximum UV transmission (see DVGW W 294-1:2006-06).

[0011] Therefore, ensuring a constant dose across the entire dose range requires special precautions, especially when the penetration depth of radiation varies over time.

[0012] By appropriately increasing the radiated power above the critical threshold, for example, by 10... 4 More than twice the amount of radiation, in principle, sufficient radiant power to reduce bacterial growth can be obtained in all areas of the liquid to be disinfected.

[0013] In traditional UV reactors, sufficient UVC radiation is typically present to ensure adequate dosage even under varying turbidity levels. For this purpose, UVC lamps, particularly gas discharge lamps, have been used. However, due to the low cost per watt of radiation source and the fact that these sources can theoretically emit large amounts of radiation (hundreds to thousands of watts, depending on the lamp type), a significant excess of the required radiation can occur. In the simplest case, a "worst-case scenario" (the most turbid liquid) can be assumed when designing a sterilization system, and the reactor and radiation source can be designed for this condition. However, this approach leads to a substantial reduction in system energy efficiency due to UV excess in most of the irradiated area.

[0014] This strategy is uneconomical for semiconductor UV sources (such as LEDs) because the maximum UV radiation is significantly lower, and current UV-LEDs, especially UV-C-LEDs, are very expensive. Furthermore, this approach wastes energy when the turbidity of the medium is relatively low. Summary of the Invention

[0015] Therefore, the object of the present invention is to further improve a universal device for irradiating flowing liquids using electromagnetic radiation, especially UV radiation, that overcomes the aforementioned disadvantages. In particular, the radiation effect, especially the sterilization effect, should be ensured as effectively as possible, even if the penetration depth changes (e.g., due to changes in the scattering and absorption characteristics of the liquid to be irradiated or sterilized).

[0016] This objective is achieved by a device having the features of claim 1 for irradiating, in particular sterilizing, a flowing liquid. Advantageous further modifications of the device according to the invention and the inventive design are the subject of the dependent claims, the description, and the drawings.

[0017] The starting point is a device for irradiating / sterilizing a flowing liquid by means of UV radiation. This device includes a container having an inlet for receiving the liquid and an outlet where the liquid can be discharged after flowing through the container. Therefore, this document essentially relates to a flow reactor. However, the present invention includes a liquid located in a container, which is pre-entered into the container, irradiated / sterilized by ultraviolet radiation, and then discharged.

[0018] Inside the container, an irradiation zone is provided for the liquid to be irradiated, into which electromagnetic radiation can enter from the bottom (i.e., the lower side of the container). Furthermore, air bubbles are positioned above the liquid level. The terms "gas" or "bubble" here should broadly include single gases and any mixtures of different gases (e.g., especially air or air bubbles). The liquid level forms the interface between the liquid and the air bubbles in the container; due to the difference in refractive indices of the two media, the liquid level acts as a reflector for radiation radiating from the lower side of the container, thus contributing to increased efficiency. The gas pressure and expansion of the air bubbles inside the container, and ultimately the cross-sectional area of ​​the liquid or the thickness or depth of the liquid layer in the irradiation zone, can be adjusted by a gas supply unit, preferably located on the top side of the container.

[0019] This ensures that a minimum amount of radiation penetrates the liquid layer across the entire irradiation zone of the reactor, the liquid layer adapting to the corresponding liquid properties (e.g., turbidity) at its depth. For example, as liquid turbidity increases, gas pressure increases, causing bubbles to expand more, thus reducing the remaining depth of the liquid until equilibrium is reached. Conversely, once turbidity decreases, gas pressure can decrease again, causing bubbles to shrink and liquid depth to increase until equilibrium is reached again.

[0020] In an advantageous further improvement of the device according to the invention, a sensor-based closed-loop control loop is provided, in which the thickness of the layer through which radiation passes is adjusted according to the UV transmittance of the medium through which the radiation is transmitted, for example, according to a sensor signal of the light being transmitted, for example from one or more photodiodes.

[0021] For example, closed-loop control can be achieved by varying the pressure of a gas supply (gas ballast device) connected to the bubble based on sensor signals. The required pressure change can be performed, for example, thermally, by means of a pump, or by volume compression ("balloon principle"). In this case, the closed-loop control is designed, for example, to cause the bubble to expand as the photodiode signal decreases due to turbidity, thereby reducing the liquid cross-section or liquid depth.

[0022] For example, closed-loop control can also be designed so that, for example, by means of a controllable valve, the volumetric flow rate in the reactor decreases as turbidity increases. This reduces the internal pressure of the container or the inlet and outlet pipes. As a result, bubbles can expand and the thickness of the liquid layer flowing through the irradiation zone decreases to an equilibrium value.

[0023] The turbidity of the medium can be measured in the inlet area (inlet) or outlet area (outlet). For example, an additional secondary radiation source (auxiliary or measuring radiation source) can be used for this purpose. In this case, one or more wavelengths can be used to address the different absorption and scattering characteristics of the medium in a targeted manner.

[0024] Sensors (such as photodiodes) can measure the direct radiation, forward scattering, and back scattering of auxiliary radiation, thereby partially distinguishing the absorption and scattering of radiation.

[0025] Both primary and secondary radiation sources and sensors can be equipped with optical components such as lenses, TIR lenses (total internal reflection), CPC (compound parabolic concentrators), apertures, reflectors, lens plates, and / or optical diffusers.

[0026] Control signals can also be determined without auxiliary radiation, but rather by means of the main radiation. For this purpose, sensors (e.g., photodiodes) are placed directly at or within the reactor vessel. In this case, the radiation from the main source can be used to determine the optical properties of the medium. However, it must be considered that the optical properties of the reaction chamber also change with the position of the boundary layer. Therefore, the position of the boundary layer is determined acoustically, for example, by means of ultrasound. The optimal new position of the boundary layer can be determined based on the boundary layer position and the photodiode signal. The photodiode signal and the current position of the boundary layer are also used to control the gas pressure. Here, the functional relationship is strongly dependent on the reactor geometry and must be determined individually for each reactor design.

[0027] Furthermore, the size of the bubbles and the thickness of the liquid layer can be controlled based on the lifespan of the radiation source (e.g., UVC-LED). This can compensate for or at least reduce the impact of the decrease in radiation power over time on liquid sterilization.

[0028] Since the irradiation intensity in the reactor decreases with increasing distance from the UV radiation source, it is desirable to be able to adjust the flow rate of the medium in the irradiation zone at depth in order to obtain a uniform radiation dose in volume.

[0029] One embodiment includes a V-shaped narrow section of the reactor or other shaped baffles or guide plates extending from above into the reactor vessel. Movable orifice plates with different orifice sizes are also feasible. The guide plates or baffles are adjusted according to the location of the boundary layer. Since the irradiation intensity is maximum near the source and decreases with increasing distance, the baffles reduce the volumetric flow rate with increasing distance, making the dose (the product of irradiation intensity and irradiation duration) independent of the distance relative to the source.

[0030] To improve reactor efficiency by optimizing interface reflectivity, objects (such as spheres or balls) can be introduced that float on the liquid surface and reflect or diffusely backscatter the light. Floating membranes are also feasible.

[0031] The boundary layer can also be excited by acoustic waves. Due to the change in refractive index between the liquid and the gas, the boundary layer can thus reflect radiation by total internal reflection, acting like a reflector. This excitation can also generate two-dimensional patterns on the liquid surface using multiple actuators. It is particularly advantageous to generate waves in the shape of a four-sided or six-sided pyramid. For this, excitation at higher harmonic frequencies based on Fourier series is also required.

[0032] Furthermore, a thin liquid film with a refractive index different from that of the host medium can be allowed to float on the host medium, thus realizing a Bragg mirror. Wavelength-sensitive reflective layers can be achieved through constructive interference of waves from different surfaces. Therefore, it is possible to distinguish between the measurement wavelength and the effective wavelength. In this case, the optical path length through each layer (formed by the product of the layer's refractive index and geometric thickness) must be one-quarter of the effective wavelength.

[0033] It also allows for irradiation of the medium from the bubble side. The advantage of this arrangement is that it prevents contamination (such as the formation of biofilms or calcium deposits) at the boundary layer.

[0034] In addition to bubble volume, flow rate (volume flow rate), baffle and source current can also be controlled by sensor signals.

[0035] As a substitute for or supplement to air, bubbles can be filled with other gases (such as O3, Cl2, ClO2, H2O2) that have additional bactericidal effects.

[0036] Furthermore, a photocatalytically active coating can be provided on the upper surface of the container in the bubble region to interact with UV radiation passing through the boundary layer between the liquid and air (radiation cycle). For example, the coating can be configured such that:

[0037] By reflecting or diffusely scattering incident radiation, a shielding effect is achieved against external forces.

[0038] Additional bactericidal effects can be achieved through absorption in photocatalytically active materials (such as TiO2 and ZnO), such as photocatalytic oxidation (PCO).

[0039] It can also be configured so that bubbles temporarily occupy the entire reactor space. By emptying the reactor space in this way, biofilm can be specifically targeted at the sterilization reactor.

[0040] Further advantages, features, and details of the invention will become apparent from the following description of preferred embodiments and with reference to the accompanying drawings. For simplicity, the same or similar features will also be indicated by the same reference numerals hereinafter. Attached Figure Description

[0041] This is shown here:

[0042] Figure 1A schematic diagram of a UV reactor with bubbles according to the present invention is shown;

[0043] Figure 2 A schematic flowchart of one embodiment for controlling the thickness of the liquid layer in a UV reactor is shown;

[0044] Figure 3 A schematic diagram of a UV reactor with baffles according to the present invention is shown;

[0045] Figure 4 A schematic diagram of a baffle for a UV reactor according to the present invention is shown;

[0046] Figure 5 A schematic diagram of a UV reactor with reflective spheres floating on the surface of a liquid, according to the present invention, is shown.

[0047] Figure 6 It shows a difference Figure 1 A schematic diagram of the inlet and outlet of the UV reactor. Detailed Implementation

[0048] Figure 1 A simplified cross-sectional view of an exemplary embodiment of the present invention is shown. This schematic diagram illustrates a UV reactor 10, which includes a container 20 for a liquid 26 to be sterilized, an inlet pipe 22, and an outlet pipe 24. The inflowing or outflowing liquid 26 is indicated by corresponding arrows. Figure 1 As shown, the inlet and outlet pipes can also be arranged differently, for example, on the lower side of the container (not shown). Liquid 26 typically fills only a portion of the container 20, up to level 28. The height H of the liquid level 28 is adjusted by the bubble 30. For this purpose, gas enters the container 20 through a gas supply section 34 located on the top side 32 of the container 26. By changing the gas pressure (indicated by a wide double arrow), the expansion of the bubble 30 can be adjusted, thereby regulating the height H of the liquid level 28.

[0049] Alternatively or additionally, the height H of the liquid level 28 can be adjusted by changing the volumetric flow rate of the liquid 26. For this purpose, a control valve 25 is provided in the inlet pipe 22. Reducing the volumetric flow rate also reduces the liquid pressure in the inlet pipe 22, thereby reducing the liquid pressure in the container 20. Thus, even under constant gas pressure, the bubble 30 can expand more and lower the height H of the liquid level 28.

[0050] A radiation source 38 is disposed on the lower side 36 of the container 26 and extends at least a portion of the lower side 36. This radiation source is preferably a plurality of UV-C-LEDs (e.g., OSLON UV 3636 type from OSRAM Opto Semiconductors). During operation, the radiation source 38 irradiates the liquid 26 within the irradiation zone 40 through the lower side 36 of the container 26. In this way, the layer thickness of the liquid 26 to be irradiated in the irradiation zone 40 is ultimately adjusted by adjusting the height H of the liquid level according to the turbidity of the liquid 26. Alternatively, the radiation source 38 can also be configured such that the liquid is irradiated from one side of a bubble, for example, by a radiation source (not shown) disposed on the top side of the container or inside the container.

[0051] Optionally, a sensor-based closed-loop control circuit (not shown) is provided, which independently adjusts the appropriate layer thickness or the height H of the liquid level 28 based on the measured UV transmittance of the liquid 26, and readjusts it as needed. For this purpose, a secondary UV radiation source 50 and three associated radiation sensors 52, 54, and 56 for measuring direct, scattered, or backscattered UV radiation are provided in the region of the inlet pipe 22. The gas pressure in the bubble 30 is controlled by means of a controllable gas supply or gas ballast device (not shown) based on the measurement signals from the radiation sensors 52, 54, and 56.

[0052] Alternatively, the UV transmittance of the outflowing liquid 26 can also be measured in the region of the outlet pipe 24 (not shown).

[0053] In another alternative embodiment, radiation sensors are positioned in the region of the top layer 32 (not shown) (for measuring direct and scattered radiation) and the region of the bottom side 36 (for measuring backscattered radiation). In this case, the radiation from the main radiation source 38 can be used to determine the UV transmittance of the liquid 26. However, the position of the liquid level 28 (i.e., the position of the optical boundary layer between the liquid 26 and the gas 39) must also be considered, as this position affects the optical properties of the reactor chamber 10. The position of the boundary layer 28 can be determined, for example, by means of ultrasound. Figure 2 A rough flowchart 100 for closed-loop control of layer thickness H in response to changes in liquid turbidity is shown for this embodiment. The measurement signal from the radiation sensor (step S110) and the determined boundary layer position (step S120) both influence the determination of the new position of boundary layer 28 (step S130). In the next step S140, the gas pressure required for the new position of boundary layer 28 is determined. Figure 1 In the case shown where turbidity is measured using an additional secondary UV radiation source 50, step S120 is omitted.

[0054] Figure 3A simplified cross-sectional view of another embodiment of the invention is shown. The UV reactor 10' has a baffle 42 that is immersed in the liquid 26 in a manner substantially perpendicular to the liquid level 28 or the main flow direction 44. The immersion depth is variable (indicated by a thin double arrow). The baffle 42 is used to regulate the flow rate of the liquid 26 at different depths in order to achieve a radiation dose as uniform as possible across the liquid volume in the irradiation zone 40.

[0055] Figure 4 A schematic top view of the baffle 42 is shown along the main flow direction 44. The baffle 42 has a basic rectangular shape with a V-shaped cutout 46 of length L that opens along the immersion direction. This V-shaped cutout 46 influences the flow profile of the liquid 26 in the irradiation zone 40, causing the flow rate to decrease with distance from the radiation source 38, or conversely, to increase with depth relative to the liquid level 28. This improves the uniformity of the radiation dose at different depths. Preferably, the length L of the cutout 46 is set such that the cutout extends to the maximum envisioned height H of the liquid level 28 to ensure flow rate regulation. An alternative embodiment of the baffle includes an orifice plate, wherein the orifice size preferably decreases along the direction of the liquid level (not shown). Multiple baffles (e.g., one in front of the bubble and one behind the bubble) are also feasible to control the flow rate over a wider area.

[0056] Figure 5 A simplified cross-sectional view of another embodiment of the invention is shown. The UV reactor 10” has a plurality of spheres or spheres 48 floating on the liquid level 28, reflecting or at least diffusely backscattering radiation. At least a portion of the radiation from the radiation source 38 that remains after passing through the liquid layer is reflected back into the liquid 26 by the spheres 48, and this radiation is not reflected by the interface between the liquid 26 and the gas of the bubble 30, but is transmitted through the interface. This improves the efficiency of the UV reactor 10”.

[0057] Figure 6 A simplified cross-sectional view of another embodiment of the invention is shown. In the case of this UV reactor 10", an inlet pipe 22 and an outlet pipe 24 are provided at the lower side 36 of the container 20. A gas supply container 58 is also provided, which is connected to the gas supply section 34 at the top side 32 of the container 20, thereby connecting to the bubble 30. By heating or cooling the gas supply in the container 58, the gas pressure can be increased or decreased, and thus the expansion of the bubble 30 can be increased or decreased. For this purpose, the gas supply container is equipped with heating and cooling devices (not shown). Alternatively, the pressure can also be increased by means of compression, for example by connecting a gas compressor to the gas supply device or by designing the gas storage container as a compressible bellows (not shown).

[0058] This invention relates to an apparatus for sterilizing, particularly flowing, liquids by means of electromagnetic radiation irradiation, and especially by means of UV radiation (UV reactor). The apparatus includes a container having an inlet for receiving the liquid and an outlet for discharging the liquid from the container. A variable or adjustable irradiation zone is provided inside the container for irradiating the liquid with electromagnetic radiation, particularly UV radiation, emitted by a radiation source. In the irradiation zone, the liquid is arranged in the form of a liquid layer with a thickness H extending between the lower side of the container and expanding air bubbles above the liquid layer. By adjusting the expansion of the air bubbles inside the container, for example by changing the gas pressure, thereby changing the liquid layer thickness H in the irradiation zone, efficient operation of the (UV) reactor is achieved at different liquid turbidities. Optionally, a sensor is used to detect the penetration depth of the radiation, and the layer thickness H is appropriately adjusted according to the sensor signal.

[0059] Explanation of reference numerals in the attached figures

[0060] 10, 10', 10”, 10”' UV reactor

[0061] 20 containers

[0062] 22 Inlet pipe

[0063] 24 Export pipe

[0064] 25 Control valve

[0065] 26 Liquid

[0066] 28 Liquid Level

[0067] 30 bubbles

[0068] 32. Top side of the container

[0069] 34 Gas Supply Department

[0070] 36. The bottom of the container

[0071] 38 radiation sources

[0072] 40 Irradiation Zone

[0073] 42 baffles

[0074] 44. Main flow direction

[0075] 48 V-shaped incision

[0076] 50 balls / sphere

[0077] 50 secondary radiation sources

[0078] 52 Radiation Sensor

[0079] 54 Radiation Sensors

[0080] 56 Radiation Sensors

[0081] 58 Gas supply container

[0082] H - Liquid level height / layer thickness

[0083] Length of LV-shaped cut

Claims

1. A device (10, 10', 10'', 10''') for irradiating a liquid (26) with electromagnetic radiation, the device comprising: - Container (20) having an inlet (22) for receiving liquid (26) and an outlet (24) for discharging liquid (26) from said container (20). - Wherein, an irradiation zone (40) for irradiating liquid (26) is provided inside the container (20). - At least one radiation source (38) is disposed on the lower side (36) of the container (20) and configured to emit electromagnetic radiation having wavelengths in the UV radiation range into the irradiation area (40) through the lower side (36). - The device (10, 10', 10'', 10''') is designed to have the effect of generating bubbles (30) in the container (20) and above the liquid level (28) of the liquid (26) in the container (20) to adjust the layer thickness (H) of the liquid (26) in the irradiation zone (40).

2. The apparatus (10, 10', 10'', 10''') according to claim 1, wherein the apparatus includes an adjustable gas supply unit (34) for adjusting the expansion of bubbles (30) in the container (20) to adjust the resulting layer thickness (H) of the liquid (26).

3. The apparatus (10, 10', 10'', 10''') according to claim 2, wherein the gas supply unit (34) is disposed on the top side (32) of the container (20).

4. The apparatus (10''') according to claim 2 or 3, wherein the expansion of the bubble (30) is adjusted according to the gas pressure of the gas supply device (58) connected to the gas supply unit (34).

5. The apparatus according to any one of claims 1-3, wherein the apparatus comprises a sensor (52, 54, 56) designed for measuring the properties of a liquid.

6. The apparatus of claim 5, wherein the apparatus includes a measuring radiation source (50) designed and configured to emit measuring radiation for the sensors (52, 54, 56).

7. The apparatus of claim 5, wherein the apparatus includes a closed-loop control circuit designed to control the expansion regulation of the bubble (30) in the container (20) based on the measurement signals of the sensors (52, 54, 56).

8. The apparatus according to any one of claims 1-3, wherein the apparatus comprises one or more radiation-reflecting objects floating on the liquid level (28).

9. The apparatus according to any one of claims 1-3, wherein the inner side of the container (20), at least in the region of the bubble (30), is provided with a coating that reflects radiation or includes a photocatalytic material with bactericidal effect.

10. The apparatus according to any one of claims 1-3, wherein the bubble (30) comprises air.

11. The apparatus according to any one of claims 1-3, wherein the bubble (30) contains a gas having a bactericidal effect.

12. The apparatus (10, 10', 10'', 10''') according to claim 1, wherein the liquid (26) is a flowing liquid.

13. The apparatus (10, 10', 10'', 10''') according to claim 1, wherein the apparatus is used to sterilize the liquid (26) by means of UV radiation.

14. The apparatus (10, 10', 10'', 10''') according to claim 1, wherein the UV radiation apparatus is a UV reactor.

15. The apparatus (10, 10', 10'', 10''') according to claim 1, wherein the at least one radiation source (38) is an LED.

16. The apparatus (10, 10', 10'', 10''') according to claim 1, wherein the UV radiation is UV-C radiation.

17. The apparatus (10, 10', 10'', 10''') according to claim 1, wherein the electromagnetic radiation is light.

18. The apparatus of claim 5, wherein the characteristic of the liquid is turbidity.

19. The apparatus of claim 8, wherein one or more radiation-reflecting objects are floating membranes or floating spheres (48).

20. The apparatus according to claim 11, wherein the gas is O3, Cl2, ClO2, or H2O2.

21. A method for irradiating a liquid with electromagnetic radiation, the method comprising: Provide the apparatus (10, 10', 10'', 10''') according to claim 1; Connect the inlet (22) of the device (10, 10', 10'', 10''') to the source of the liquid (26), and connect at least one radiation source (38) to the power supply source; The liquid (26) is introduced into the container (20) through the inlet (22); Gas (30) is introduced into the container (20) through the gas supply unit (34); The expansion of the bubbles (30) in the container (20) is adjusted according to at least one property of the liquid (26) to adjust the resulting layer thickness (H) of the liquid (26) in the irradiation zone (40).

22. The method of claim 21, wherein adjusting the expansion of the bubble (30) is achieved by one or more of the following method steps: - Adjust the gas pressure of the bubble (30); - Adjust the volumetric flow rate of the liquid (26).

23. The method according to claim 21 or 22, further comprising: At least one property of the liquid (26) is measured by means of sensors (52, 54, 56), and the measurement signal of said sensors (52, 54, 56) is used to make the expansion of said bubble (30) adapt to the change of the measurement signal.

24. The method according to claim 21 or 22, further comprising: The liquid (26) is returned to the source or transferred to another reservoir through the outlet (24).

25. The method according to claim 21 or 22, further comprising: The bubble (30) is expanded to occupy the entire space in the container (20) for a period of time.

26. The method according to claim 21, wherein the method is used to sterilize the liquid (26).

27. The method of claim 21, wherein at least one characteristic of the liquid is turbidity.

28. The method of claim 23, wherein at least one characteristic of the liquid is turbidity.

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