Modular UV irradiation apparatus for liquids

Abstract

This document describes an apparatus for irradiating suspensions or emulsions with UVB or UVC tubes, which is of a completely modular design. In this apparatus, the suspension is passed through long, thin quartz glass tubes in a module. These tubes are arranged side-by-side in a base frame and secured by clamping plates and sealing rings. Modules containing the UV tubes and internally mirrored plates are mounted on the outside of the module, forming a closed chamber and preventing radiation from escaping. The apparatus can be easily configured with regard to flow rate, residence time of the suspension in the irradiation chamber, and any required radiation intensity by simply attaching components. Dimmable UVC tubes and an integrated radiation meter allow for precisely adjustable radiation exposure. The interior can be cooled by purging with cold air, thus preventing a temperature increase of the suspension. The irradiation modules, located on the sides and in the middle, can be removed for cleaning or tube replacement without interrupting the flow of the suspension or emulsion through the quartz glass tubes.

Description

[0001] The ultraviolet spectrum of light is divided into three parts: UVA, UVB, and UVC radiation. UVC radiation covers a wavelength range between 100 and 280 nm. The disinfecting effect of UVC radiation has been demonstrated in various studies, in which 90% of the emitted radiation had a wavelength of 253.7 nm. The effect of UV radiation is based on the Grotthus-Draper law: only those portions of the radiation that are absorbed by the irradiated object are effective. Specifically, electromagnetic oscillations are absorbed by the object, which lead to the excitation and ionization of molecules in the irradiated object. The energy thus supplied breaks various chemical bonds, such as single and double carbon bonds. UVC radiation is therefore particularly effective in proteins and nucleic acids. Amino acids and the proteins constructed from them exhibit an absorption maximum at a wavelength of 280 nm.In chain-like nucleic acids, relevant absorption processes occur primarily at the bases adenine, guanine, cytosine, and thymine. These have an average absorption maximum at a wavelength of 260 nm. Irradiation with UVC light thus affects the cell nucleus and the cell wall. This suggests that UVC radiation in the spectrum around 260 nm is, in principle, capable of damaging or killing microorganisms.

[0002] This type of UVC irradiation aims to kill unwanted microorganisms such as bacteria, viruses, and fungi with a sufficiently high radiation dose, thus sterilizing water or air. Numerous devices are available for this purpose, all equipped with tubes or lamps that emit UVC radiation. In a flow-through process, the medium to be sterilized, either air or water, is passed past the UVC tubes, whereby a maximum diameter of the layer thickness must not be exceeded to guarantee effectiveness.

[0003] In the field of microalgae cultivation, the use of UV irradiation is considerably more complicated, as these are living organisms that must be administered a certain dose of radiation, but the destruction of the microalgae or serious damage to the cell membrane or nucleus itself must be prevented. In addition, in a dense suspension of algae, the penetration depth of the radiation is reduced to a few millimeters due to absorption by the organisms. UV irradiation of microalgae aims at two completely different modes of action: Mode of action 1

[0004] When cultivating microalgae in an optimized nutrient solution, there is always a risk of contamination with fungi, bacteria, viruses, or competing algal strains, which leads to damage and, in most cases, total loss of the algae, combined with the complex cleaning and sterilization measures required for the equipment. However, certain microalgae have an extremely stable and highly pigmented cell envelope that is at least largely resistant to UVC rays. This is not the case for most pests, however, which suggests that an irradiation intensity of strength X kills the bacteria / viruses / fungi but does not cause lasting damage to the microalgae themselves. Thus, irradiation with UVC tubes can partially or completely reverse contamination with these organisms. Mode of action 2

[0005] Microalgae produce chlorophyll, lipids, fatty acids, and other components through photosynthesis. They also possess sensors that detect deteriorating environmental conditions, whereupon they begin converting the chlorophyll into carotenoids to protect themselves from increasing radiation, dehydration, and further damage. This fact is well known to science, and specific irradiation rates have been developed for microalgae strains to stimulate the production of these valuable carotenoids with appropriate UVC or UVB irradiation.

[0006] Both modes of action require special technical features of the apparatus. The apparatus operates in a flow-through process, and thus the suspension layer thickness must be kept low to treat organisms close to the radiation source and those further away as equally as possible. Furthermore, the flow velocity of the suspension must be between 0.3 and 0.5 m / s to prevent the microalgae from adhering to any vessel walls. A sufficiently long residence time in the irradiation area must also be ensured, both for modes 1 and 2 described above. Accordingly, the apparatus must be capable of being extended as required. The flow rate should correspond to the incoming and outgoing volumes to avoid unnecessary shear forces on the organisms. The tubes through which the flow occurs must also be made of quartz glass, as only this is permeable to rays with a wavelength of 253 nm.

[0007] These are requirements that the known and existing UV irradiation devices do not meet. These are designed for the sterilization of water or air and operate with a radiation intensity that is guaranteed to kill germs across the entire layer thickness. In the absence of a dosable device, the task was to develop one for the treatment of microalgae cultures using modes 1 and 2.

[0008] The newly developed UV irradiation device described above has a modular design and can be configured for any flow rate, any required radiation intensity, and any desired irradiation duration. Furthermore, it can be quickly and completely disassembled and constructed in such a way that all individual components can be perfectly cleaned and disinfected. Even the ready-to-use device can be sterilized using the peroxide vacuum process to log6, meaning it is 99.9999% sterile. Furthermore, it can be equipped with both UVC and UVB tubes, making it universally applicable in the field of microalgae technology.

[0009] The apparatus consists of a narrow base frame (1) into which quartz glass tubes (2) with a relatively thin cross-section are integrated. This is referred to in this description as the quartz glass tube module (25). A narrow cross-section is extremely important to ensure almost complete penetration of the radiation even in dense suspensions. A diameter of < 30 mm, but preferably of around 25 mm with a wall thickness of 2 mm, has proven ideal. Since the radiation occurs 360° around the quartz glass tube, the radius of the suspension to be penetrated is then only 11.5 mm. This can even be achieved with dense media. Turbulence also occurs when flowing through the long quartz tubes, so constant mixing of the suspension enables the best possible distribution of the amount of radiation.The quartz glass tubes should be long enough to allow for a long irradiation time and also allow for convenient assembly and cleaning. A preferred and technically feasible length for quartz tubes is between 1.2 and 1.8 m. If a very long dwell time of the organisms in the irradiation chamber is planned, several such modules can be arranged one behind the other by simply flanging them together, thus extending the total length of the quartz glass tubes through which the fluid flows.

[0010] A further advantage of this apparatus is that the suspension with the microalgae as the interface only touches the quartz glass tube itself on the inside and not the UV tubes attached to the outside. In existing UV treatment apparatus, a UV tube is usually integrated into a container, resulting in multiple interfaces. Adhesion of the organisms quickly and significantly reduces the radiation intensity of the UV lamps, resulting in the partial or complete loss of the desired effect of sterilization or activation of carotenoid formation. Several quartz glass tubes (2) are then arranged vertically or offset from one another in the internally mirrored metal frame (1) in a quantity that corresponds to the total flow in a circulating system.If the required flow rate is very high, several modules (25, 26) can be arranged in parallel, and the inflow can be divided accordingly in an inlet / outlet system (27, 28). Oppositely arranged openings (29, 30) are provided in this laterally open quartz glass tube module, into which cold air is blown and the heated air is discharged. A temperature sensor (32) measures the current temperature and automatically controls the supplied cold air accordingly. This allows the temperature within the apparatus to be controlled, preventing heating of the suspension.

[0011] Box-shaped parts made of metal or a suitable plastic with an open side are attached to each side of this module (25), which consists of a metal frame (1) with the quartz glass tubes (2). These box-shaped parts contain the UVC or UVB tubes (18) and are fastened in corresponding lamp sockets (17). The inner surfaces are mirrored so that the radiation is optimally distributed throughout the entire apparatus, even by reflection from the outer walls (15, 21). The parts attached to the sides ensure that the apparatus is hermetically sealed; no radiation can escape to the outside, thus eliminating any danger to personnel. To prevent the apparatus from overheating, a fan is integrated to keep the temperature level stable at a predetermined value. A radiation measuring device (31) is integrated so that the radiation intensity in the apparatus can be adjusted to a desired value using the dimmable UV tubes (18).On the irradiation modules (26) there is a cable duct (19) at the top and bottom through which the power cables (20) are led.

[0012] If several modules with quartz tubes (25) are now assembled in parallel, a frame section with UVC or UVB tubes (15) is arranged between each of them and one of the box-shaped modules with UVC or UVB tubes (26) described above is arranged only on the outside sides. These light modules (26) are ideally only attached to the frame construction with the quartz tubes (1) with a tab (16), but can also be screwed on. The middle sections (15) with UV tubes are pushed from above between the two frame constructions with the quartz tubes (1) and locked in place. This means that all of the light modules (26) can be removed within a few seconds, for example to change the UV tubes (18) or to clean the UV tubes, the mirrored inner surfaces or the outside of the quartz glass tubes. A measuring device (31) is integrated into the apparatus and continuously measures the current radiation intensity.This allows for replacement within minutes if the UV tubes fail or lose their intensity. This does not even require interrupting the flow of the suspension, which is a huge advantage in a pressurized and closed system.

[0013] To make the entire apparatus cost-effective, efficient, and easy to assemble, the quartz glass tubes (2) are pushed through the holes (4) in the base frame, provided with silicone sealing rings (13), and fastened to the base frame (1) using a clamping plate (3) with similar holes. This clamping plate (3) can be made of a solid, corrosion-resistant material adapted to the medium. To prevent the microalgae from adhering to it, a Teflon-coated stainless steel plate is recommended, which is fastened with screws and sealing rings underneath. The base frame and the clamping plate are chamfered in the area of ​​the silicone sealing ring so that the sealing ring (13) is squeezed against the quartz glass tube, locking it in place and creating a pressure-tight zone. For attaching the clamping plate (3) to the frame (1) of the quartz glass tube module, there are corresponding holes (5) in the plate, through which a screw connection is made.The screw (9) and the corresponding nut are sealed by seals (12).

[0014] The base frame (1) of the quartz glass tube module (25) has a flange (6) on the vertical side, which, in conjunction with the horizontal profile (11), forms a pre-chamber (14) in which the suspension is distributed into the individual quartz glass tubes (2). If several quartz glass tube modules (25) are used one after the other, the suspension is mixed in this pre-chamber (14), thus ensuring optimal irradiation of all suspension or emulsion particles. The flange (6), like the clamping plate (3), is sealed by a groove (7, 8) with a corresponding O-ring or gasket. The flange (6) also has corresponding holes (10) for screwing to other modules (25) or the inlet and outlet (27, 28).

[0015] The inlet and outlet (27) consist of a cone (24) with a flange and a pipe section (23) with a flange (22), which connects to the existing piping system. This section can be designed as a single section (27), a double section (28), or a triple section for connection to corresponding quartz tube modules.

[0016] In the horizontal base frame (11) of the quartz tube module (25), in the area of ​​the pre-chamber (14), an inlet / outlet valve (33) is arranged, through which a medium vacuum can be generated in the entire quartz glass tube module (25) and then a vacuum peroxide sterilization process can be carried out, which coats all internal interfaces, including the long quartz glass tubes, with peroxide and thus ensures perfect sterilization of the entire apparatus. Reference number list A single UV apparatus B 2-UV apparatus C 3-UV apparatus 1 base frame quartz glass tube module 2 quartz glass tubes 3 clamping plate 4 Hole for the quartz glass tube 5 Hole for screwing the clamping plate to the base frame 6 flange quartz glass tube module 7 Groove for O-ring on the flange, with seal 8 Groove for O-ring on the clamping plate, with seal 9 Screw for fastening the clamping plate to the base frame 10 Hole for screwing the flange with additional modules or inlet / outlet 11 Horizontal profile of the base frame 12 seals of the clamping plate screw connection 13 Seal on the quartz glass tube 14 Prechamber of the quartz glass tube module 15 frame irradiation module, open on the side, mirrored inside 16 Suspension bracket 17 lamp bases 18 UVC or UVB tubes 19 cable duct 20 power cables 21 Side panel, mirrored inside 22 Flange pipe connection 23 pipe 24 cone 25 quartz glass tube modules 26 Irradiation module 27 Inlet-Outlet 28 2-way inlet-outlet 29 Cold air injection 30 Air discharge 31 Radiation measuring device 32 temperature sensors 33 Inlet-outlet valve prechamber

Claims

[1] Apparatus characterized by that it can be assembled from several modules by simply flanging and attaching them, and can be configured for any flow rate, any required radiation intensity and any desired irradiation duration. [2] Equipment characterized by that the suspension or emulsion flows through the irradiation chamber in thin quartz glass tubes and the medium can be largely completely penetrated by the UV radiation. [3] Apparatus characterized by that the quartz glass tubes are firmly fixed in a frame by means of a clamping plate and correspondingly soft seals, but can be dismantled very quickly and easily by loosening this clamping plate and stripping off the seals. [4] Equipment characterized bythat by attaching the irradiation modules to the quartz glass tube modules, a hermetically sealed irradiation chamber is created, which prevents any danger to personnel from escaping UVC radiation. [5] Equipment characterized by that the suspension or emulsion in the pre-chambers is mixed again before entering the glass tubes, thus ensuring the best possible and even irradiation of all particles. [6] Equipment characterized by that the irradiation modules can be removed to clean the UV tubes or the mirrored surfaces or to replace UV tubes without having to interrupt the flow of the suspension or emulsion through the quartz glass tubes themselves. [7] Apparatus characterized bythat radiation meters are integrated into the irradiation modules, which can automatically regulate the intensity of the dimmable UV tubes and thus always ensure a defined radiation exposure in the entire apparatus. [8] Equipment characterized by that the entire interior can be air-conditioned by supplying cold air controlled by a thermostat, thus avoiding heating of the suspension or emulsion. [9] Apparatus characterized by that a flow rate of the suspension can be set in the quartz glass tubes, which on the one hand prevents adhesion to the inner walls and on the other hand prevents shear forces that damage the microorganisms themselves. [10] Apparatus characterized by that the entire interior is mirrored, and through direct irradiation or reflection on the outer walls, a largely 360° irradiation of the quartz glass tubes prevails.

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