WO2020164646A1

WO2020164646A1 - Apparatus for treatment of liquids

Info

Publication number: WO2020164646A1
Application number: PCT/CZ2019/050003
Authority: WO
Inventors: Jiri Drimal
Original assignee: Jiri Drimal
Priority date: 2019-02-11
Filing date: 2019-02-11
Publication date: 2020-08-20

Abstract

Apparatus for treatment of liquids, comprising - an inlet compartment for supplying the liquid to be treated and an outlet compartment for discharging the treated liquid, - a source of UV radiation for emitting UV radiation, said source of UV radiation having a longitudinal axis, - at least one first pair of primary partitions (11) extending along the source of UV radiation, thereby forming the first pair of slits (2) extending in parallel to the longitudinal axis of the source of UV radiation, said slits (2) being delimited between the primary partition (11) and the outer surface of the source of UV radiation or outer surface of the enclosure of the latter, - at least one second pair of primary partitions (11) extending along the source of UV radiation, thereby forming the second pair of slits (2) extending in parallel to the longitudinal axis of the source of UV radiation, the slits (2) being delimited between the primary partition (11) belonging to said second pair and the outer surface of the source of UV radiation or outer surface of the enclosure of the latter, and - at least one pair of mixing partitions (11'), which are arranged between the first and second pairs of primary partitions (11).

Description

Apparatus for treatment of liquids

Field of the invention

The present invention relates to an apparatus for treatment of liquids, comprising an inlet compartment for supplying the liquid to be treated and an outlet compartment for discharging the treated liquid, and a source of UV radiation, preferably a UV discharge tube.

Background of the invention

Currently, disinfection of liquids by means of UV radiation having a wavelength in the 250 nm band already belong among standard methods for liquid disinfection. Compared to the chlorine disinfection of water / liquids, the use of UV radiation for disinfection does not cause any harmful residues to remain in treated liquids. Commonly used sources of UV radiation are low-pressure or medium pressure discharge tubes. Typical structure of UV reactor comprising a low pressure and a medium-pressure UV discharge tube is shown in Figs. 1A and 1 B. The prior art apparatuses for treating liquids by means of UV radiation can comprise, for example, a low-pressure UV discharge tube 1 that is provided with a quartz enclosure and that is arranged inside the reactor in a substantially coaxial manner. The liquid to be treated is supplied into the reactor through the inlet 4. Subsequently, the liquid flows along the quartz enclosure of the UV discharge tube 1 and then it is discharged through the outlet 5. The quartz enclosure prevents the liquid from coming into contact with the discharge tube and protects the latter from being damaged by particles, such as stone chips, contained in the liquid to be treated. On the other hand, such enclosure is permeable to UV radiation. Thanks to the quartz enclosure, it is possible to replace an inoperative UV discharge with a new one without draining the reactor. Another material, which is permeable to UV radiation, such as teflon, can be used instead of the quartz enclosure. Besides that, the UV discharge tube can be coated with a thin foil which is also permeable to UV radiation and which prevents shards from entering into the liquid to be treated in the case that the UV discharge tube breaks.

The structural design of the reactor usually envisages that the gap 2 arranged between the enclosure of the discharge tube and the wall of the reactor 3 is several centimetres wide, which means that the depth D of the layer of the liquid to be treated amounts to several centimetres, such as about 4 cm or more for drinking water. Since the UV radiation is absorbed by the liquid, the strength of the UV rays and thus also the efficiency of the disinfection of the treated liquid have their highest values in the region adjoining the surface of the (quartz) enclosure of the UV discharge tube 1. Accordingly, the strength of the UV rays and thus also the efficiency of the disinfection of the treated liquid assume their lowest values in the region along the inner wall of the reactor 3. The UV radiation dose (given by the retention time of the liquid in the UV reactor and by the radiation strength) received by the liquid when passing along the UV discharge tube is higher in comparison to that received by the liquid when passing along the inner wall of the UV reactor. Thus, the disinfection of the liquid passing through the UV reactor is not uniform.

In order to achieve a more uniform disinfection effect within the entire volume of the liquid to be treated, various modifications of the basic arrangement of a UV reactor were devised. One of the possible methods consists in that the width of the gap between the enclosure of the discharge tube and the wall of the reactor, i.e. the depth of the layer of the irradiated liquid, is reduced, the final width values being about 2 centimetres. One of the drawbacks of the aforesaid technical solution, however, consists in that the flow rate of the liquid to be treated must be

simultaneously reduced in order to achieve the same degree of efficiency of the disinfection process. Another drawback of the latter technical solution consists in that a considerable proportion of the UV radiation passes through the liquid towards the inner surface of the reactor where such proportion is subsequently absorbed without being utilized. That causes the efficiency of the process to remain relatively low. Consequentially, the total cost related to the liquid treatment process increases.

The UV radiation is also used for disinfecting sewage water, the respective method consisting in that the effluent to be treated is led through a system of open channels where UV discharge tubes are arranged in a direction, which is parallel to the flow direction or perpendicular to the same, the spacing of the discharge tubes amounting to several centimetres.

At the present time, the most efficient disinfection and oxidation technology used for water treatment is considered to be the so called advanced oxidation process (AOP). This technology is based on making use of OH radicals for treating liquids. The oxidizing potential of the latter technology is higher than that of a technology based, for example, on the use of chlorine or ozone. There are several methods of generating such OH radicals within the liquid to be treated. One of those methods consists in the dosage the amount of hydrogen peroxide added to the liquid to be treated and in the subsequent exposure of said peroxide to the standard UV radiation (200 nm - 400 nm). The lifespan of such OH radicals is very short (several milliseconds). Another method consists in dissolving ozone in the liquid to be treated and in the subsequent exposure of the liquid to the standard UV radiation. Typically, ozone is generated in generators using corona discharge to produce ozone. Besides that, ozone can be generated in the atmosphere when the latter is exposed to a UV radiation having a wavelength shorter than 200 nm, particularly the so called VUV radiation (10 - 200 nm). The latter method of ozone generation, however, is less efficient when compared to that based on an electric discharge. In this case, the concentration of ozone is much lower, as well. The lower the concentration of ozone, the weaker the efficiency of dissolving of ozone in water. Thus, the prior art systems, which use solely the UV radiation for generating OH radicals, do not offer a sufficient degree of efficiency. Moreover, such systems need a number of technological components, such as a UV reactor and a mixing device for dissolving gaseous ozone in water.

Another method of generating ozone consists in dispersing a photocatalytic material in the liquid to be treated. The subsequent exposure of the liquid to UV radiation causes OH radicals to be produced. The permeability of the liquid to UV radiation depends on the amount of the photocatalytic material distributed within the liquid. In order to ensure an efficient utilization of the whole amount of the distributed photocatalytic material, the entire volume of the liquid to be treated must be irradiated. The prior art apparatuses do not enable such an objective to be achieved.

Hence, the objective of the present invention is to propose an apparatus for treating liquids which would provide for the most extensive and uniform UV

disinfection of the whole volume of the liquid to be treated, disregarding the quality thereof (i.e. disregarding the properties thereof causing a low or high degree of absorption of the UV radiation used) and which would simultaneously enable a short wave VUV radiation to be used for treating the whole volume of the liquid by means of an advanced oxidation technology, both the treatment processes taking place in a single apparatus. Another objective of the present invention is to propose an apparatus for treating liquids which would enable the whole amount of liquid to be treated in the most efficient and uniform manner, the liquid being exposed both to that type of UV radiation, which is absorbed by the liquid in a relatively low proportion, and to that type of UV radiation, which is absorbed by the liquid very rapidly.

Summary of the invention

The above objective is fulfilled by providing an apparatus as defined by the appended patent claims. Such apparatus for treatment of liquids comprises

- an inlet compartment for supplying the liquid to be treated and an outlet compartment for discharging the treated liquid,

- a source of UV radiation for emitting UV radiation, said source of UV

radiation having a longitudinal axis,

- at least one first pair of primary partitions extending along the source of UV radiation, thereby forming the first pair of slits extending in parallel to the longitudinal axis of the source of UV radiation, said slits being delimited between the primary partition and the outer surface of the source of UV radiation or outer surface of the enclosure of the latter,

- at least one second pair of primary partitions extending along the source of UV radiation, thereby forming the second pair of slits extending in parallel to the longitudinal axis of the source of UV radiation, the slits being delimited between the primary partition belonging to said second pair and the outer surface of the source of UV radiation or of its enclosure, and

- at least one pair of mixing partitions, which are arranged between the first and second pairs of primary partitions,

the first and second pairs of primary partitions being arranged in a manner, which enables the treated liquid to be led from the inlet compartment through the first pair of slits along the surface of the source of UV radiation or of its enclosure as well as through the second pair of slits along the surface of the source of UV radiation or of its enclosure into the outlet compartment, and the mixing partitions being arranged in a manner, which enables the treated liquid to be led along the mixing partitions from the surface of the source of UV radiation or of its enclosure after having passed through the first pair of slits and/or before passing the second pair of slits.

In a preferred embodiment, the inlet and outlet compartments are arranged inside a reactor, wherein preferably the inlet for supplying the liquid to be treated into the inlet compartment and the outlet for discharging the treated liquid from the outlet compartment have a mutual spacing, as measured along the longitudinal axis of the source of UV radiation, corresponding to at least 50 %, preferably at least 70 %, of the length of the source of UV radiation inside the reactor (3), most preferably ranging between 80 and 100 % of said length.

According to further preferred embodiment, the inlet and outlet compartments are arranged inside a channel, wherein preferably, the channel comprises an array of sources of UV radiation, said sources being mutually spaced along a plane extending perpendicularly to flow direction of the liquid being supplied into the inlet

compartment.

It is preferable for all embodiments, when the primary partitions and/or the mixing partitions are made of stainless steel or Teflon or quartz glass or MgF2 or ceramics or their combinations.

Also preferably, the primary partitions and/or the mixing partitions and/or the inner walls of the apparatus are provided with a photocatalytic or electro- photocatalytic coating or layer.

Advantageously, at least some of the walls surrounding the inlet compartment and/or the outlet compartment are provided with a UV reflective layer.

The primary partitions or at least those portions thereof, which face the source of UV radiation, may be at least partially moveable or bendable in order to enable the width of the respective slit to be adjusted.

For some embodiments, it may be advantageous, when at least one slit is delimited between the outer surface of the source of UV radiation or of its enclosure and the free edge of the primary partition, said edge extending in a radial or tangential direction or in parallel to the tangential direction with respect to the source of UV radiation.

It is advantageous for all embodiments, when the mixing partitions are arranged with their longitudinal edges adjoining the source of UV radiation or its enclosure.

And it is also preferable, when the source of UV radiation is:

- a low-pressure discharge tube for emitting UV radiation having the

wavelengths of 254 nm and 185 nm, or

- a medium-pressure discharge tube for emitting UV radiation having the wavelengths longer than 200 nm and UV radiation having the wavelengths shorter than 200 nm, and/or

the source of UV radiation is provided with an enclosure made of quartz or with an enclosure made of MgF2.

To increase the mixing effect, a free longitudinal edge of at least one mixing partition is provided preferably with protrusions or cut-outs or indentations.

It is advantageous for all embodiments, when the through slits are adapted for diverting the liquid to be treated from the inlet compartment into the outlet

compartment along a portion of the surface of the source of UV radiation or along that of the enclosure of the same in a layer having the width of up to 5 mm, the source of UV radiation being also adapted for emitting VUV radiation.

The apparatus further preferably comprises auxiliary catalytic elements which are at least partially made of a photocatalytic or electro-photocatalytic material or are at least partially coated with a photocatalytic or electro-photocatalytic material, said auxiliary catalytic elements being arranged in the inlet compartment and/or in the outlet compartment and/or in the mixing compartment.

The prior art UV systems for treating drinking liquids use solely the radiation having the wavelength of 254 nm, which is emitted by a low pressure UV discharge tube, for disinfecting a liquid, although such low-pressure discharge tube is also able to emit radiation having a shorter wavelength, such as 185 nm. The radiation with the wavelength of 185 nm is absorbed by a layer of water / liquid having several millimetres in thickness, whereas the typical radiation with the wavelength of 254 nm is absorbed by a layer of water having several tens or hundreds of millimetres. The geometrical arrangement of the known UV reactors is designed with regard to the low absorption of UV radiation having the wavelengths around 254 nm. Hence, it is not possible to utilize a shorter wavelength, namely that of 185 nm, for treating liquids in the prior art reactors.

When the liquid is exposed to the UV radiation having the wavelength of less than 200 nm, a photolytic process (photochemical reaction) is initiated within that liquid and free OH radicals are generated in a very thin layer. Thus, the liquid can also be treated by means of the advanced oxidation technology (AOP) without being enriched with additional substances or without having to be processed in an apparatus for dissolving ozone in water. Thus, the utilization of a photolytic process is considered to be the most efficient method for generating OH radicals in water by means of UV radiation. The novel system has also been designed with regard to the possibility of employing photocatalytic or electro-photocatalytic materials for treating liquids. After the surface of such photocatalytic materials has been exposed to UV radiation, OH radicals are produced, said OH radicals having a higher oxidizing potential compared to, e.g., chlorine or ozone, the latter substances being typically used for disinfecting water. Various types of photocatalytic materials, such as those based on T1O2, can be used.

As used for the purpose of the present disclosure, the term“liquid to be treated” refers to a liquid, such as water, which contains or may contain pollutants, such as microorganisms, and which may further contain the above mentioned photocatalytic or electro-photocatalytic materials or the like.

Brief description of the drawings

The present invention will be described further in more detail with reference to the accompanying drawings showing exemplifying embodiments, wherein Fig. 1A shows a prior art apparatus in a longitudinal sectional view, Fig. 1 B shows the apparatus of Fig. 1A in a plan view, Fig. 2A shows the first exemplifying embodiment of the apparatus according to the invention in a longitudinal sectional view, Fig. 2B shows the apparatus of Fig. 2A in a plan view, Fig. 3 shows the second exemplifying embodiment of the apparatus according to the invention, Fig. 4 shows a plan view of the third exemplifying embodiment, Fig. 5 shows a plan view of the fourth

exemplifying embodiment, Fig. 6 shows a plan view of the fifth embodiment, Fig. 7 shows the sixth embodiment of the invention in a vertical sectional view, Fig. 8A shows the seventh embodiment, and Fig 8B shows the apparatus of 8A in a plan view.

Description of exemplary embodiments

The first exemplary embodiment of the apparatus for treatment of liquids according to the invention is shown in Figs. 2A and 2B. This embodiment comprises a cylindrical reactor 3 inside which a UV discharge tube 1 for generating UV radiation with wavelengths of 254 nm and 185 nm is arranged. For the purpose of the following description and in the accompanying drawing, the UV discharge tube 1 does not include just the discharge tube itself but also an enclosure of the latter, if any, such enclosure being preferably made of quartz. According to the present exemplary embodiment, the UV discharge tube 1 is arranged coaxially along the axis of the reactor 3, extending over the entire length of the latter. In addition, the first pair of primary partitions 11 , the first pair of mixing partitions 11‘ and the second pair of primary partitions 11 are arranged inside the reactor. The primary partitions extend from the inner wall of the reactor 3 towards the UV discharge tube 1 and the mixing partitions 11‘ extend from the UV discharge tube 1 towards the cylindrical inner walls of the reactor 3. Thus, the interior space of the reactor 3 is divided by the partitions into an inlet compartment, which comprises an inlet 4 for supplying the liquid to be treated, the inlet being arranged at one end of the reactor 3, a pair of mixing compartments, each containing one of the mixing partitions 1 T, and an outlet compartment which comprises an outlet 5 for discharging the treated liquid, the outlet being arranged at the other end of the reactor 3.

Thus, the inlet compartment is delimited by a portion of the wall of the reactor 3, by the first pair of primary partitions 11 and by a portion of the surface of the UV discharge tube 1.

The outlet compartment is delimited by a portion of the wall of the reactor 3, by the second pair of primary partitions 11 and by a portion of the surface of the UV discharge tube 1.

Each of the mixing compartments is delimited by a portion of the wall of the reactor 3, by one of the partitions of the first pair of primary partitions 11 , by one of the partitions of the second pair of primary partitions 11 and by a portion of the surface of the UV discharge tube 1. Besides that, each of the mixing compartments is partially partitioned by one of the mixing partitions 11 ', said partitioning enabling a by-pass gap 20 to be left between the respective mixing partition 11‘ and the corresponding wall of the reactor 3.

The inlet compartment is interconnected with the mixing compartments through a first pair of slits 2, which extend along the UV discharge tube 1 and are arranged between the outer surface of said UV discharge tube 1 or the outer surface of the enclosure of the same, on the one hand, and the primary partitions 11 belonging to the respective first pair, on the other hand. Similarly, the mixing compartments and the outlet compartment are interconnected through a second pair of slits 2, which extend along the UV discharge tube 1 and are arranged between the outer surface of said UV discharge tube 1 or the outer surface of the enclosure of the same, on the one hand, and the primary partitions 11 belonging to the respective second pair, on the other hand. All of the slits 2 have the same with ranging between

I and 5 mm, said width being constant along the entire length of the respective slit.

The by-pass gap 20 formed between the mixing partition 1 T and the corresponding wall of the reactor 3 can be significantly wider than the slits 2.

The length of the reactor 3 and the corresponding length of the UV discharge tube 1 are designed in relation to the width of the slits 2 as well as consideration of the required flow rate of the liquid to be treated.

When the apparatus is in use, the liquid, which has been supplied into the inlet compartment, flows into the respective mixing compartment exclusively through the first pair of slits 2, where it is led in a shallow layer along the surface of the UV discharge tube 1 or along the surface of the enclosure of the latter. Subsequently, the liquid is diverted by the mixing partitions 11‘ from the surface of the UV discharge tube 1 or from the surface of the enclosure of the latter towards the walls of the reactor 3. Thereby, the liquid is stirred and then it flows exclusively through the second pair of slits 2, into the outlet compartment. This occurs, once again, in a shallow layer flowing along the surface of the UV discharge tube 1 or along the surface of the enclosure of the latter. Thereby it is ensured that the whole amount of the liquid gets in a close proximity of the UV discharge tube 1 when passing through the first pair of slits 2 and the second pair of slits 2, such close proximity being sufficient for enabling the liquid to be properly treated by the UV radiation.

The dimensions of the slit 2, which is arranged between the primary partitions

I I and the surface of the enclosure of the UV discharge tube 1 made of quartz glass and which enables the liquid to be treated to pass through, are selected in an extent that prevents the UV radiation, which is necessary for generating OH radicals, from being completely absorbed by the liquid. The width of the slit 2 is up to approximately 5 mm, preferably up to 3 mm, most preferably approximately 1 mm.

According to alternative embodiments, the reactor can have a shape, which is different from the cylindrical one. Thus, that the reactor can have e.g. an oval cross section or the like.

The only difference between the second embodiment of the apparatus according the present invention and the first one consists in the arrangement of the regions where the inlet 4 and the outlet 5 are connected to the reactor 3.

The inlet 4, which is intended for supplying the liquid into the inlet

compartment, can be led into the reactor 3 through a radial wall, as indicated in Fig. 3, or through a side wall, as indicated in Figs. 2A and 2B. Similarly, the outlet 5 for discharging the treated liquid from the outlet compartment can be arranged in the radial wall according to the arrangement shown in Fig. 3 or led through the side wall according to the arrangements shown in Figs. 2A and 2B.

The third embodiment of the apparatus according the present invention, which is shown in Fig. 4, comprises three pairs of primary partitions 11 and two pairs of mixing partitions 1 T, the liquid to be treated being led from the inlet compartment by means of the first pair of primary partitions 11 into the first pair of slits 2, where the liquid is led along the surface of the UV discharge tube 1 , and subsequently by means of the first pair of mixing partitions 11‘ towards the side walls of the reactor 3. After having been stirred in the preceding step, the liquid is led by means of the second pair of primary partitions 11 into the second pair of slits 2, where it flows along the surface of the UV discharge tube, and subsequently by means of the second pair of mixing partitions 11‘ towards the side walls of the reactor 3. After having been stirred in this manner again, the liquid is diverted by means of the third pair of primary partitions 11 into the third pair of slits 2 through which it is discharged along the surface of the UV discharge tube 1 into the outlet compartment. Owing to the increased number of the partitions 11 and 1 T, an even higher degree of efficiency and homogeneity of the liquid treatment process can be achieved.

The primary partitions 11 and or the mixing partitions 11‘ and/or the walls of the reactor 3 are preferably at least partially coated with a layer of photocatalytic materials.

According to another embodiment, which is not shown in the drawings, the edges of the mixing partitions 11‘ facing the corresponding wall of the reactor 3 are provided with cut-outs or protrusions for increasing the efficiency of the mixing process.

According to the embodiment shown in Fig. 5, at least the primary partitions 11 , or at least those portions of the same, which face the surface of the UV discharge tube 1 , are flexible or tiltable with respect to the surface of the UV discharge tube, the tilting action being initiated by the pressure of the liquid passing through or, in a controlled manner, by an actuating mechanism. Thereby, the widths of some, preferably of all of the slits 2 can be adjusted as required. For example, the primary partitions 11 can be bendable or movable so that an increase in the pressure of the liquid to be treated causes the pressure forces of the liquid to act on the free edges of the partitions, thereby drawing the same further apart from the outer surface of the UV discharge tube 1 and making the respective slit 2 wider. For the above purpose, the partitions 11 can be made of an elastic material. Alternatively, the end portions of the free edges of the partitions can be provided with springs for biasing the partitions 11 in a position delimiting the narrowest allowable slit 2 or, as the case may be, in a position where the edges are substantially in contact with the outer surface of the UV discharge tube 1 , thereby making it possible that the forces acting on the partitions 11 cause a change in the shape thereof, such changed shape delimiting a slit 2 being wider than the original one. According to another advantageous embodiment, a stop member may be provided for delimiting the maximum allowable distance of the free edge of the partition 11 from the UV discharge tube 1 , thereby defining the width- wise range of the slit 2. According to an alternative embodiment, only certain portions of the partitions 11 can be bendable or movable, namely those portions of the partitions 11 that are oriented towards the UV discharge tube 1.

According to still another embodiment, which is not shown in the

accompanying drawings, some or all of the primary partitions 11 and/or mixing partitions 11‘ do not extend towards the UV discharge tube 1 in a radial direction but, for example, in a tangential direction or in parallel to a tangential plane, said partitions delimiting, again along with the UV discharge tube 1 , the required width of the slits 2. Even in the latter embodiment, a technical solution enabling the widths of the slits 2 to be controlled can be advantageous, such technical solution being similar to that described above.

A single reactor can contain two or more UV discharge tubes 1 arranged therein. In such an embodiment, the primary partitions 11 and the mixing partitions 11 ' can be arranged around a plurality of UV discharge tubes, the respective slits 2 and by-pass gaps 20 assuming a sequential arrangement, as described above, or a mutually parallel arrangement.

Alternatively, the reactor 3 can comprise just a single inlet compartment provided with an inlet orifice for supplying the liquid to be treated, yet a pair of the UV discharge tubes 1 and a pair of outlet compartments, the liquid to be treated being led from the inlet compartment into the first or second outlet compartment along the first or second UV discharge tube 1 , respectively. When flowing between the inlet and outlet compartments, the liquid sequentially passes through the corresponding one of the slits 2 delimited by the primary partitions 11 , through the by-pass gap 20 delimited by the mixing partitions 11‘ and, finally, through the other slit 2. Similarly, both the first and the second embodiment of the invention, as described above, can be further modified, such modification consisting in that just a single inlet

compartment but a pair of the UV discharge tubes 1 and a pair of outlet

compartments are provided.

In addition, the edges of the primary partitions can be provided with elements for inducing a micro-turbulence effect. The latter elements can be formed, for example, by doubling the respective partition 11 in the area of the free edge thereof, which edge is oriented towards the UV discharge tube 1 , or by creating a surface micro-relief on the primary partition 11 concerned.

According to further embodiments of the present invention, which are shown in Figs. 6 and 7, a channel 40, through which the liquid to be treated can pass, is used instead of the reactor 3. Inside the channel 40, the UV discharge tubes 1 are situated in a mutually spaced arrangement. The primary partitions 11 are arranged along the UV discharge tubes 1 , wherein the outer surfaces of the UV discharge tubes 1 and the terminating edges of the primary partitions 11 delimit the slits 2 having from 1 to 5 millimetres in width and extending in parallel to the longitudinal axis of the corresponding UV discharge tube 1. In addition, the mixing slits 11‘ are arranged within the apparatus in a manner enabling the liquid, which has passed through the slit 2 along a certain portion of the respective UV discharge tube 1 , to be led through the corresponding mixing slit 11‘ from the surface of said UV discharge tube and, subsequently, through the next slit 2 along another portion of the UV discharge tube 1.

The UV discharge tubes 1 , along with the corresponding partitions 11 , can be arranged in the vertical direction (as shown in Fig. 6) or in the horizontal direction, i.e. perpendicularly to the flow direction of the liquid to be treated (as shown in Fig. 7), or horizontally and obliquely with respect to the flow direction of the liquid to be treated (not shown). According to the embodiments shown in Figs. 6 and 7, the primary partitions 11 form guiding surfaces for leading the liquid to be treated towards the respective UV discharge tubes 1 , an acute angle being included between said primary partitions 11 and the flow direction of the liquid being supplied for treatment. Two pairs of partitions are assigned to each UV discharge tube 1 , one pair of the partitions 11 being arranged upstream of the UV discharge tube 1 and the other pair of the partitions 11 being arranged downstream of the UV discharge tube 1 in terms of the flow direction, whereby four slits 2 are formed in the region of each UV discharge tube 1. There are arranged therebetween the mixing partitions 1 T for mixing the liquid to be treated after its passing through the first slit 2 and before its entering the second slit 2.

According to further, alternative embodiments, which are based on those shown in Figs. 6 and 7, the primary partitions 11 , which belong to the first pair of primary partitions 11 associated with the respective UV discharge tube 1 , extend in a perpendicular direction with respect to the flow of the liquid being supplied for treatment. In terms of the flow direction, the latter partitions can be arranged upstream of the UV discharge tubes 1 or in alignment with the UV discharge tubes 1. Nevertheless, the primary partitions are always arranged in a manner that enables a continuous slit 2 having the width up to 5 millimetres to be formed between the respective partition 11 and the outer surface of the UV discharge tube 1 or the outer surface of the enclosure of the latter.

In order to achieve an even higher degree of efficiency, the liquid to be treated can be led through two or more sequential reactors of the type described above. For this purpose, various types of reactors can be combined.

The partitions 11 can be made of a metal, preferably of stainless steel.

Flowever, other suitable materials are also conceivable, such as quartz glass, regular glass, teflon, MgF2 or the like. Both the surfaces of partitions 11 , 1 T and the inner side of the UV reactor 3 can be coated with a suitable photocatalytic or electro- photocatalytic material. When irradiated with the UV light, said surfaces emit free OFI radicals, thereby further increasing the efficiency of the liquid treatment process.

The reactor 3 can be made of stainless steel or of any other suitable material that is resistant to water / liquids as well as the UV light. Such suitable materials can include glass, plastics or quartz, the outer surfaces thereof being preferably coated with an additional material reflecting UV light, an example of such material being aluminium. The inner surface of the reactor 3 can be coated with a thin film made of teflon or the like.

In a preferred embodiment, the reactor 3, or the respective channel, is made of a material that is permeable to UV radiation, an example of such material being quartz glass. The outer surface of the reactor 3 is coated with a layer made of a UV reflecting material, an example of such material being aluminium. Thereby, a higher percentage of the UV radiation impinging on the inner wall of the reactor 3 and reflected back into the liquid can be achieved. As already mentioned above, the inner wall of the reactor 3, or that of the respective channel, can be coated with a photocatalytic material.

The embodiment shown in Figs. 8A and 8B is substantially similar to those shown in Figs. 2a to 5, the main difference consisting in that auxiliary catalytic elements are provided, said elements being formed by an array of disks 12 made of or covered with a photocatalytic material. According to this particular embodiment, the disks 12 are arranged coaxially along the axis of the source 1 of UV radiation inside the reactor and one upon the other, thereby forming mutually spaced rings around the source 1 of UV radiation. The interior circumference of these rings adjoins the source 1 of UV radiation, whereas the exterior circumference of the same is arranged spaced from the interior circumference of the reactor 3. In addition, cut-outs are provided both in the first region facing the side wall of the reactor 3, along which the liquid flows from the inlet 4 arranged inside the inlet compartment, and in the second region facing the side wall of the reactor 3, along which the liquid flows towards the outlet 5 arranged inside the outlet compartment. Thereby, both supplying of the liquid into the first pair of the slits 2 and discharging of the liquid into the outlet compartment can be considerably facilitated at all the levels of the reactor.

Owing to both the presence of a photocatalytic material and the irradiation by the UV rays generated by the source 1 , a photocatalytic process can take place within the liquid, said process causing the contained pollutants to chemically decompose. At the same time, the disks 12 help to mix the liquid after the liquid has passed through the first pair of slits and before the same passes through the second pair of slits. This arrangement significantly contributes to the increased efficiency of the apparatus.

The auxiliary catalytic elements may also assume other than disk shapes and may also be arranged in an oblique direction with respect to the axis of the reactor 3 or in parallel to the latter axis. Alternatively, these elements may assume a concave or convex shape or may be provided with protrusions or cut-outs. According to yet another preferred embodiment, the catalytic elements can be made of an electro- catalytic material or at least partially coated with such material.

According to all of the embodiments described herein, the length-to-width ratio of the slit 2 is preferably greater than 10:1 , more preferably greater than 20: 1 , and most preferably greater than 100:1 , in order that the width-wise constriction existing in the region of the slit can be compensated for by the length of the same.

For the purpose of the present disclosure, the term UV discharge tube should encompass all kinds of sources of UV radiation providing at least two different wavelengths or emitting a continuous spectrum, one of the wavelengths or one portion of the emitted spectrum being completely absorbed within a thin layer of liquid having depth of several millimetres and the other wavelength or the other portion of the emitted spectrum being only partly absorbed within such layer of liquid. More particularly, the source of UV radiation for the apparatus according to the present invention is preferably constituted by such source that emits exclusively or predominantly VUV rays having a wavelength of less than 200 nm (e.g. 185 nm) and that is additionally able to produce a UV radiation having a wavelength of more than 200 nm (e.g. 254 nm).

Hence, a suitable source of UV radiation can be a low-pressure UV discharge tube (e.g. a mercury or amalgam vapour discharge tube), a medium-pressure UV discharge tube (emitting a continuous spectrum ranging from about 160 nm to about 500 nm), an excimer UV light source, a LED UV light source or the like. A suitable UV radiation source can also be composed of two or more partial UV light sources. For example, such source of UV radiation can comprise an array of LED UV light sources, the individual LED sources emitting UV light having equal or different wavelengths. Such an array of LED UV light sources forming a complete source of UV radiation can be arranged in a common enclosure or on a common supporting structure. Alternatively, the individual LED UV light sources can be interconnected in another suitable manner. A suitable UV radiation source can also be composed of a combination of different types of UV light sources. For example, a low-pressure UV discharge tube can be located in the centre of the respective UV reactor and several LED UV light sources can be located on the enclosure of the same UV reactor.

Although preferred embodiments have been described above, it is clear, that a person skilled in the art easily finds further possible alternative embodiments.

Therefore, the scope of protection is not to limited to the above exemplifying embodiments, but rather it is defined by the appended claims.

Claims

PATENT CLAIMS

1. Apparatus for treatment of liquids, comprising

- a source of UV radiation for emitting UV radiation, said source of UV

radiation having a longitudinal axis,

- at least one first pair of primary partitions (11 ) extending along the source of UV radiation, thereby forming the first pair of slits (2) extending in parallel to the longitudinal axis of the source of UV radiation, said slits (2) being delimited between the primary partition (11 ) and the outer surface of the source of UV radiation or of its enclosure,

characterized in that it further comprises

- at least one second pair of primary partitions (11 ) extending along the source of UV radiation, thereby forming the second pair of slits (2) extending in parallel to the longitudinal axis of the source of UV radiation, the slits (2) being delimited between the primary partition (11 ) belonging to said second pair and the outer surface of the source of UV radiation or outer surface of the enclosure of the latter, and

- at least one pair of mixing partitions (11 '), which are arranged between the first and second pairs of primary partitions (11 ),

the first and second pairs of primary partitions (11 ) being arranged in a manner, which enables the treated liquid to be led from the inlet compartment through the first pair of slits (2) along the surface of the source of UV radiation or of its enclosure as well as through the second pair of slits (2) along the surface of the source of UV radiation or of its enclosure into the outlet compartment, and the mixing partitions (11‘) being arranged in a manner, which enables the treated liquid to be led along the mixing partitions (11‘) from the surface of the source of UV radiation or of its enclosure after having passed through the first pair of slits (2) and/or before passing the second pair of slits (2).

2. Apparatus according to claim 1 , characterized in that the inlet and outlet

compartments are arranged inside a reactor (3).

3. Apparatus according to claim 2, characterized in that the inlet (4) for supplying the liquid to be treated into the inlet compartment and the outlet (5) for discharging the treated liquid from the outlet compartment have a mutual spacing, as measured along the longitudinal axis of the source of UV radiation, corresponding to at least 50 %, preferably at least 70 %, of the length of the source of UV radiation inside the reactor (3), most preferably ranging between 80 and 100 % of said length.

4. Apparatus according to claim 1 , characterized in that the inlet and outlet

compartments are arranged inside a channel (40).

5. Apparatus according to claim 4, characterized in that it comprises an array of sources of UV radiation, said sources being mutually spaced along a plane extending perpendicularly to flow direction of the liquid being supplied into the inlet compartment.

6. Apparatus according to any of the preceding claims, characterized in that the primary partitions (11 ) and/or the mixing partitions (11‘) are made of stainless steel or Teflon or quartz glass or MgF2 or ceramics or combinations thereof.

7. Apparatus according to any of the preceding claims, characterized in that the primary partitions (11 ) and/or the mixing partitions (11 ') and/or the inner walls of the apparatus are provided with a photocatalytic or electro-photocatalytic coating or layer.

8. Apparatus according to any of the preceding claims, characterized in that at least some of the walls surrounding the inlet compartment and/or the outlet

compartment are provided with a UV reflective layer.

9. Apparatus according to any of the preceding claims, characterized in that the primary partitions (11 ) or at least those portions thereof, which face the source of UV radiation, are at least partially moveable or bendable in order to enable the width of the respective slit (2) to be adjusted.

10. Apparatus according to any of the preceding claims, characterized in that at least one slit (2) is delimited between the outer surface of the source of UV radiation or of its enclosure and the free edge of the primary partition (11 ), said edge extending in a radial or tangential direction or in parallel to the tangential direction with respect to the source of UV radiation.

11. Apparatus according to any of the preceding claims, characterized in that the mixing partitions (11‘) are arranged with their longitudinal edges adjoining the source of UV radiation or its enclosure.

12. Apparatus according to any of the preceding claims, characterized in that the source of UV radiation is:

- a low-pressure discharge tube (1 ) for emitting UV radiation having the wavelengths of 254 nm and 185 nm, or

- a medium-pressure discharge tube (1 ) for emitting UV radiation having the wavelengths longer than 200 nm and UV radiation having the wavelengths shorter than 200 nm,

and/or

13. Apparatus according to any of the preceding claims, characterized in that a free longitudinal edge of at least one mixing partition (11 ') is provided with protrusions or cut-outs or indentations.

14. Apparatus according to any of the preceding claims, characterized in that the through slits (2) are adapted for diverting the liquid to be treated from the inlet compartment into the outlet compartment along a portion of the surface of the source of UV radiation or along that of the enclosure of the same in a layer having the width of up to 5 mm, the source of UV radiation being also adapted for emitting VUV radiation.

15. Apparatus according to any of the preceding claims, characterized in that it further comprises auxiliary catalytic elements which are at least partially made of a photocatalytic or electro-photocatalytic material or are at least partially coated with a photocatalytic or electro-photocatalytic material, said auxiliary catalytic elements being arranged in the inlet compartment and/or in the outlet compartment and/or in the mixing compartment.