WO2024105056A1

WO2024105056A1 - Solar powered water-treatment device

Info

Publication number: WO2024105056A1
Application number: PCT/EP2023/081797
Authority: WO
Inventors: Michael Georg FORSTHOFER
Original assignee: Forsthofer Michael Georg
Priority date: 2022-11-14
Filing date: 2023-11-14
Publication date: 2024-05-23

Abstract

The invention relates to a solar-powered water-treatment device (10) for treating raw water (20) in order to produce clean water, having at least one transparent or translucent outer wall (12, 14, 44, 46), which encloses an interior (24) that is equipped with a first reservoir (18) for receiving the raw water (20), a collecting container (38, 48) for receiving the raw water, and an evaporation device (32), wherein the evaporation device (32) has a transport layer (34) and an evaporation layer (36), and a section (33) of the evaporation device (32) is arranged so as to be immersed into the raw water (20).

Description

DESCRIPTION

Solar powered water treatment device

The invention relates to a solar-powered water treatment device for treating raw water into pure water, comprising at least one transparent or translucent outer wall enclosing an interior space.

Such water treatment devices are known in various versions. What they have in common is that raw water, for example salty sea water or dirty water, evaporates in the interior and condenses on at least one of the outer walls. The energy for the evaporation process is obtained by solar radiation entering the interior through the outer wall (greenhouse effect).

As the temperature inside the building rises above the temperature outside, the inside surfaces of the exterior walls are colder than the air inside the building after a certain time. As soon as the humidity inside the building is high enough, the water in the air condenses on the exterior walls.

Known water treatment devices are comparatively complex in design and require, for example, pumps to pump the raw water into a roof area of the water treatment device and let it run down an evaporation surface there.

However, in many countries in the global south where pure water or drinking water has to be obtained in this way, neither electricity nor the necessary components are available.

Against this background, the present invention has the object of developing such a water treatment device in such a way that it can be constructed using simple materials and does not require any additional resources during operation.

The object is achieved by a solar-powered water treatment device according to claim 1. Further advantageous embodiments are the subject of the dependent claims.

To achieve the object, a solar-powered water treatment device for treating raw water into pure water has at least one transparent or translucent outer wall which encloses an interior in which a first reservoir for receiving the raw water, a collecting container for receiving the pure water and a Evaporation device are arranged, wherein the evaporation device has a transport layer, wherein a portion of the evaporation device is arranged for immersion in the raw water.

The transport layer draws the water from the reservoir and can also transport the water, for example, to a certain height against gravity.

In some embodiments, the evaporation device comprises an evaporation layer.

The evaporation layer has the largest possible surface area and takes over the water from the transport layer for evaporation.

In some embodiments, a second reservoir is arranged in the interior space, wherein a second portion of the evaporation device is arranged for immersion in the raw water of the second reservoir.

Thus, the transport layer is moistened at several points, thus increasing the amount of raw water transported and evaporated.

In some embodiments, the second reservoir is located above or below the first reservoir.

The difference in height between the two reservoirs results in improved flow through the transport layer.

In some embodiments, the water treatment device has at least a first outer wall and a second outer wall arranged above the first outer wall.

This also makes it possible to build a larger water treatment device if components of the desired size are not available.

In some embodiments, the water treatment device has two vertically arranged first outer walls on which two second outer walls inclined relative to the vertical and inclined towards each other are supported to form a roof section.

This leads to increased stability of the water treatment device. In addition, the more inclined second outer walls improve the energy absorption from sunlight, as the angle of incidence of the sunlight is sharper and thus a smaller amount of sunlight is reflected than with vertical outer walls. In addition, The moist air produced by the evaporation device rises between the second outer walls and condenses particularly efficiently on their sloping inner surfaces.

In some embodiments, at least one second collecting container for receiving the pure water condensed on the second outer walls is arranged at a transition between the first outer walls and the second outer walls.

This means that the clean water does not run into a gap between the first and second outer walls, for example. If a structural element, such as a wooden slat, is arranged between the first and second outer walls, this is also kept dry.

In some embodiments, a drain siphon is arranged on or in the second collecting container for intermittent emptying of the second collecting container.

This means that the second collection container initially fills up to a certain level with pure water, which is then drained off all at once. Since this usually soon creates a closed water surface in the second collection container, less water in the second collection container evaporates again immediately. If the water from the second collection container is drained off immediately, only water droplets remain in the second collection container, which have a larger surface area in relation to their volume and are therefore subject to increased evaporation. Overall, the efficiency of the water treatment device is improved.

In a further embodiment, the drain siphon has a nozzle device which is directed towards one of the outer walls.

As a result, the drain siphon sprays one of the outer walls at regular intervals, so that water droplets on it are taken along and flushed into the first collecting container. As already described above, this reduces the evaporation rate of the pure water that has already condensed and improves the efficiency of the water treatment device overall.

In some embodiments, the transport layer comprises or is formed by a microfiber fabric and/or the evaporation layer comprises a fabric formed from fibers, for example cotton fibers.

A microfiber fabric has a particularly strong capillary effect, so that a microfiber cloth held in a container of raw water will draw the water out of the Containers can also be transported upwards against gravity. Cotton fibers are only moderately suitable for transporting water. However, they have a very large surface area, so they can evaporate the water transported by the microfiber fabric very well.

In some embodiments, the evaporation device has a pipe section-like or cup-like base body which is at least partially covered by a transport layer and an evaporation layer.

Compared to an evaporation device that is only made up of the transport layer and/or the evaporation layer, the base body has the advantage that it forms a self-supporting base that does not need to be supported.

In some embodiments, the evaporation device is inserted into the reservoir.

This makes the water treatment facility particularly easy to set up. All that is needed is to install an evaporation facility in an available outer wall or outer shell. This makes it easy to set up a water treatment facility, particularly in resource-poor regions and situations.

In some embodiments, at least one of the outer walls is formed by a tube portion, in particular by a portion of a body of a bottle.

Drinks bottles in particular are readily available even in poor or remote regions of the third world. Alternatively, transparent plastic tubes can be used.

In some embodiments, the water treatment device comprises a stackable insert for arrangement within the at least one outer wall, wherein the insert has a funnel and an evaporation device which together form a reservoir, wherein a raw water drain pipe is arranged for connection to other inserts and has a drain opening through which the next insert can be supplied with raw water.

Such inserts are suitable for the rapid construction of water treatment facilities of various sizes. Because raw water can be passed from one insert to the next, it is easy to supply a large stack of inserts with raw water from a common container.

In some embodiments, the reservoir is arranged to cool a side wall or an inner wall of the funnel. This improves the efficiency of water treatment.

Further features and variants of the invention are apparent from the attached figures, which show the inventive forms of the invention only schematically. They show in detail:

Fig. 1 shows a cross section through a water treatment device according to a

Embodiment of the invention;

Fig. 2 is a cross-section through a water treatment device according to another embodiment of the invention;

Fig. 3 is a cross-section through a water treatment device according to another embodiment of the invention;

Fig. 4 a cross-section through a plastic bottle obtained

Water treatment device according to an embodiment of the invention;

Fig. 5 is a cross-section through a stackable insert for forming a water treatment device according to an embodiment of the invention and

Fig. 6 is a cross-section through a water treatment device with a plurality of stackable inserts, according to an embodiment of the invention.

The figures contain partly simplified, schematic representations. In some cases, identical reference symbols are used for identical, but possibly not identical, elements. Different views of the same elements may be scaled differently. Directional information such as "left", "right", "top" and "bottom" are to be understood with reference to the respective figure and may vary in the individual representations compared to the object shown.

A water treatment device 10 shown in Fig. 1 has a first transparent outer wall 12 and a further first transparent outer wall 14. The first outer walls 12, 14 can be in a lower region of the

Water treatment device 10 is arranged on a base plate 16 and fastened thereto. In the lower area, a reservoir 18 for receiving raw water 20 is also arranged.

The first outer walls 12, 14 and the base plate 16 or, if no base plate 16 is provided, the ground on which the first outer walls 12, 14 are placed, together with side walls, of which only one side wall 22, which is at the rear from the viewer's perspective, is shown in Fig. 1, enclose an interior space 24.

The basic principle of the water treatment device 10 is that the raw water 20 evaporates or evaporates and precipitates on the first outer walls 12, 14, for example as water droplets 26. Undesirable components of the raw water 20, for example salt or bacteria, do not evaporate together with the water, so that the water droplets 26 contain purified water, i.e. pure water.

So that there is enough energy in the interior 24 for the evaporation of the raw water 20, at least one of the first outer walls 12, 14 is transparent or translucent. The water treatment device 10 is set up where it can be illuminated by the sun 28. The solar radiation 30 shines through the second outer wall 14 and heats the interior 22.

The material of the first outer walls 12, 14 is selected so that it absorbs as little solar radiation 30 as possible and, in turn, allows as little infrared radiation as possible to escape from the interior. This results in a greenhouse effect that heats up the interior 24. Suitable materials for the outer walls 12, 14 are, for example, Plexiglas, acrylic glass or window glass. In addition, tarpaulins or films made of suitable transparent or translucent plastics can also form the outer walls 12, 14. If necessary, the outer walls 12, 14 can have a supporting structure, for example a frame made of a rigid material, to increase rigidity.

If no transparent materials are available, the outer walls 12, 14 can also be made of translucent materials. The only important thing is that the energy that is transported through the outer wall 12, 14 into the interior 24 is sufficient to bring the interior 24 to the necessary higher temperature than the outer wall 12, 14. If, however, the outer wall 12, 14 absorbs too much energy itself, it heats up too much so that no more water drops 26 can condense on it.

In order to accelerate the evaporation process of the raw water 20, an evaporation device 32 is arranged in the interior 24, which protrudes into the raw water 20 with a section 33 arranged at its lower end. The evaporation device 32 has a transport layer 34 and an evaporation layer 36. The transport layer 34 and the evaporation layer 36 are arranged adjacent to one another and can be connected to one another. For the arrangement of the evaporation device 32, a Any fastening device can be provided, for example hooks, a frame or even a line stretched between the side walls 22.

The transport layer 34 is made of a fabric that is suitable for transporting the raw water 20 from the reservoir 18 upwards against gravity by means of capillary action. Microfiber fabrics, for example, are particularly suitable for this purpose.

The evaporation layer 36 is made of a fabric that can absorb water and evaporate it over as large a surface as possible. Fabrics made of cotton, for example, are particularly suitable for this, especially if their surface is additionally roughened. Other fabrics, for example those made of other fibers, can also be suitable as the material of the evaporation layer 36.

The evaporation layer 36 is advantageously arranged on the side of the evaporation device 32 that is illuminated by the sun 28. The evaporation layer 36 preferably has a dark color, more preferably black. Dark colors absorb radiation in general and solar radiation 30 in particular better than light colors. The dark color thus achieves better energy absorption for the evaporation of the raw water 20.

In some embodiments, a second evaporation layer 36 can be provided, which covers the transport layer 34 on the side that was previously still open, so that the transport layer 34 is covered on its two largest sides by an evaporation layer 36, for example in a sandwich-like manner. This further increases the amount of water evaporated per unit of time.

The water drops 26 collect on the outer walls 12, 14 and become larger and larger until they begin to run down the outer walls 12, 14 under their own weight. In order to collect the water drops 26 and thus the clean water, collecting containers 38 are arranged in the lower area of the first outer walls 12, 14, preferably on the floor or the base plate 26, which collect and drain the water drops 26.

In some embodiments, the collecting containers 38 can, for example, be inclined towards a side wall 22 so that the collected water collects in the area of the respective side wall 22 and can be removed there.

Fig. 2 shows a further embodiment of the water treatment device 10, wherein similar components have been provided with the same reference numerals as in Fig. 1. Second outer walls 44, 46 are placed on the first outer walls 12, 14, which are arranged essentially perpendicular to the floor or the floor plate 16. The second outer walls 44, 46 are arranged at an angle to one another so that they support one another in a roof area. As a result, the second outer walls 44, 46 are inclined relative to the vertical. Due to this inclination, the solar radiation 30 hits the second outer walls 44, 46 at a more acute angle than the first outer walls 12, 14. The steeper the angle of incidence of light on transparent, translucent or transparent materials, the higher the proportion of light that reaches the interior 24 and is not reflected. The inclined outer walls thus increase the efficiency of the water treatment device 10.

A second reservoir 40 is arranged in the interior 24 and is also filled with raw water 20. The second reservoir 40 is arranged above the reservoir 20. A second section 42 of the evaporation device 32 extends into the raw water 20 of the second reservoir 40. The transport layer 34 can thus draw raw water 20 from two sections 33, 42. This increases the amount of water that can be transported. At the same time, a moistened surface of the evaporation layer 36 increases, so that the amount of evaporating water increases.

The second reservoir 40 can be attached in any way in the interior 24. For example, as indicated in Fig. 2, it is possible to insert a shelf between the two side walls 22 on which the second reservoir 40 can be placed. Many other designs are conceivable, for example hanging the second reservoir 40 from one of the outer walls 12, 14, 44, 46.

In some embodiments, at least one of the outer walls 12, 14, 44, 46 has, for example, a condensation net, in particular in the manner of a mist catcher. In some embodiments, the outer walls 12, 14, 44, 46 are not made of rigid materials, but rather, for example, of a frame in which, for example, a tarpaulin is stretched.

In some embodiments, the second outer walls 44, 46 are also inclined toward each other relative to the vertical.

As shown in Fig. 3, second collecting containers 48 can be arranged on one or more of the outer walls 12, 14, 44, 46. The collecting containers 38, 48 are each arranged such that they can catch and/or collect water, in particular water drops 26, that run down the respective outer wall 12, 14, 44, 46. In some embodiments, the collecting containers 48 are arranged, as shown in Fig. 3, in the area in which the first outer walls 12, 14 and the second outer walls 44, 46 abut one another. In some embodiments, the second collecting containers 48 are arranged approximately, for example, at half, one third or two thirds of the height of the entire water treatment device 10.

In some embodiments, for example, additional collecting containers 38, 48 may be provided.

The second collecting containers 48 can, as shown in Fig. 3, have one or more drain siphons 50, which are arranged in or on the second collecting container 48 in such a way that they regularly empty the second collecting container 48 in a torrent. The drain siphons 50 can have an outlet that is directed towards the outer wall 12, 14, 44, 46 located below the second collecting container 48. As a result, when the second collecting container 48 is emptied, the respective outer wall 12, 14, 44, 46 is sprayed and water droplets 26 located thereon are flushed into the collecting container 38.

In some embodiments, the drain siphon 50 may, for example, have a constriction at its outlet, for example a nozzle device, by means of which the water is sprayed onto the outer wall 12, 14, 44, 46.

A siphon pump is a hydraulic component that uses the siphon principle to empty a (water) container at intervals in a torrent automatically and without the need for monitoring. To do this, the water must overflow in a downward-curved pipe or in a bell that is placed over a water level pipe. A Pythagorean cup, for example, also works according to this principle.

In further embodiments, one or more of the outer walls 12, 14, 44, 46 are removable or can be opened to gain access to the interior space 24.

In further embodiments, the water treatment device 10 has a water extraction device by means of which water or water drops 26 condensed on the outer walls 12, 14, 44, 46 can be harvested.

In further embodiments, at least one of the reservoirs 18, 40 and/or at least one of the collecting containers 38, 48 can have, for example, an insect net to protect the raw water 20 and/or the pure water from insects, in particular from their egg-laying. In further embodiments, a A surface-modifying substance, such as vegetable oil, may be introduced to make the surface unusable and/or inaccessible for insects, particularly for their egg-laying.

As can be seen from the above, the water treatment device 10 according to the invention can be manufactured from simple components and can be used in operation without additional use of resources. Nevertheless, it has a higher efficiency in the use of solar energy than known water treatment devices 10.

In further embodiments that are particularly resource-saving, the outer walls can be formed by a plastic bottle 52. The evaporation device including containers for the raw water can be provided by a bottle insert. For this purpose, the plastic bottle is cut open to place the insert inside. This has the advantage that these water bottles are collected, for example, from the sea or on beaches, etc., which is not only cost-effective, but also leads to a reduction in plastic waste.

As shown in Fig.4, the insert can be constructed like a type of pipe/cup 54 that stands in a reservoir 18 with raw water 20. The pipe/cup 54 is covered inside and outside with fabric that serves as an evaporation device 32 and is partially immersed in the pipe water 20.

In further embodiments, this evaporation device 32 has a transport layer 34 and an evaporation layer 36. The transport layer 34 and the evaporation layer 36 are arranged adjacent to one another and can be connected to one another.

The transport layer 34 is made of a fabric that is suitable for transporting the raw water 20 from the reservoir 18 upwards against gravity by means of capillary action. Microfiber fabrics, for example, are particularly suitable for this. Due to this transport, the transport layer 34 as well as the evaporation layer 36 can be continuously moistened.

The evaporation layer 36 is formed from a fabric that can absorb water and evaporate it over as large a surface area as possible. In some embodiments, the fabric can be dark colored, for example, to achieve the greatest possible absorption of sunlight. Fabrics made of cotton, for example, are particularly suitable for this purpose. To further increase the surface area, this can be additionally roughened and enlarged. Other materials, for example those made from other fibers, can also be suitable as the material of the evaporation layer 36.

In further embodiments, the tube/cup 54 is made of an absorbent material, for example a material with a capillary effect such as floral foam, thus enabling an additional transport effect and can be seen as an extension or as part of the transport layer.

The water drops 26 collect on the wall of the bottle 52 and become larger and larger due to condensation until they start to run down the walls under their own weight and the pure water collects at the bottom of the bottle.

An upper portion 56 of the bottle 52 can be inverted into an interior of the bottle 52. In some embodiments, it is also possible to cut off the upper portion 56 of the bottle 52, invert it, and insert it into the bottle 52.

The cut-off and/or inverted upper part 56 of the bottle can be located above the bottle insert, on which water drops 26 also condense and run down into a collecting container 48.

In some embodiments, the pure water is drained from the second collection container 48 onto the walls of the bottle 52 and runs down the wall of the bottle 52 with water droplets 26 thereon.

In some embodiments, the inverted upper portion 56 may be filled with raw water 20 to cool its surfaces facing the interior of the water treatment system 10.

To enhance this effect, for example, a white fabric 58 can be dipped into the raw water 20 and hung over its edges in order to cool the walls of the bottle 52 by evaporation. In addition, a cooling water collecting container 60, e.g. a plastic bag, can be put over the edges beforehand and secured so that it catches water dripping from the fabric.

Ideally, the surfaces on the outside of the bottle 52 on whose inner wall water is to condense are covered with a white cover 62 in front of the

The areas through which sunlight hits the

Evaporation device 32 can shine, should remain free. In further embodiments, several of these water treatment devices 10 can be placed on top of one another. The clean water collection containers 38 of the various water treatment systems 10 can be connected to one another using drain siphons 50 and hoses or the like, as can the raw water reservoirs 18.

In some embodiments, as shown in Fig. 5, instead of bottles 52, tubes 70 made of translucent materials, for example Plexiglas, can be used, on which, as well as on the underside of the funnels 66, the water drops 26 then condense and run down.

In further embodiments, the raw water 20 can be preparatory stored in black tubes or containers exposed to the sun in order to preheat it for the evaporation process.

In further embodiments, the evaporation device 32 can also be immersed directly in a body of water with raw water 20, for example in the sea, instead of in a raw water reservoir 18, in which case the water treatment devices 10 can then optionally be kept above water by floating bodies.

In further embodiments, larger systems can also be built using several modules as shown in Fig. 5. These modules can then be stacked on top of each other in a translucent tube 70 made of, for example, Plexiglas, as shown in Fig. 6. Such units shown in Fig. 6 can then be connected next to each other and on top of each other using state-of-the-art means, such as pipes and hoses, to form large systems that can then be used for pure water production on a larger scale. On the one hand, to make salt or sea water and other types of raw water usable for drinking water supplies, and on the other hand, due to the similarity of the pure water obtained to distilled water, an application in the production of green hydrogen is also conceivable, since there is the problem that salt/sea water cannot be used for conventional electrolysis.

An insert for constructing a water treatment device 10, as shown in Fig. 5 arranged in a translucent tube 70, has a substantially conical base body, here a funnel 66. A raw water drain pipe 64 is arranged along a central axis, which passes through a bottom of the funnel 66 and is connected to it in a watertight manner. The raw water drain pipe 64 has a drain opening 74 which is arranged as an overflow. As a result, the funnel 66 and the raw water drain pipe 64 form a reservoir 18 for receiving raw water 20.

A tube or cup 54, which is surrounded by a transport layer 34 and an evaporation layer 36, is inserted into this reservoir 18. The funnel 66 itself also has a transport layer 34 and an evaporation layer 36 on an inner side. In a partially circumferential section, an additional section 76 is placed on the funnel 66, which also has a transport layer 34 and an evaporation layer 36 on a side facing the sun 28.

A second collecting container 48 is arranged below the funnel 66 to receive the condensate water forming on the outside of the funnel 66. Clean water drain pipes 68 are arranged to project outward from the second collecting container 48 in order to drain the condensate water towards a wall of the pipe 70.

In some embodiments, the first collecting container 38 is formed, for example, by a bottom portion of the tube 70 or the bottle 52 or is arranged there so that it receives water drops 26 running down. For this purpose, it can be useful to provide a watertight connection between the first collecting container 38 and the tube 70 or the bottle 52. In some embodiments in which a tube 70 is provided as an outer wall, the first collecting container 38 can be arranged under the tube 70 and at least partially surround it or be designed to be larger than the cross section of the tube 70 so that water drops 26 dripping therefrom fall into the first collecting container 38.

Furthermore, recesses 72 are arranged under the funnel 66, which can accommodate an upper edge of the cup 54 of an insert arranged under this insert. This allows the inserts to be stacked on top of one another, as shown in Fig. 6.

The raw water drain pipe 64 is closed at an upper end and open at a lower end. At the lower end, the raw water drain pipe 64 has a section with an enlarged diameter so that raw water 20 can drain from the reservoir 18 through the drain opening 74 and into the reservoir 18 of the insert below this insert. This makes it possible, as shown in Fig. 6, to keep an entire column of inserts filled with a common reservoir for raw water 20. In some embodiments, at least one of the clean water drain pipes 68 may include a drain trap 50.

In some embodiments, the evaporation layer 36 can be formed by having one side of the transport layer 34 with an enlarged surface. This can be achieved, for example, by a weave suitable for increasing the surface area or by roughening.

In addition to microfibers and/or cotton fibers, the transport layer 34 and the evaporation layer 36 can be made of various other materials or can each have a layered structure themselves. The function of the transport layer 34 is fulfilled, for example, by substances, materials or fabrics with an increased capillary effect on water.

In some embodiments, the cup 54 or the tube 54, 70 have a cross-section that is not circular. Possible cross-sections can be, for example, oval, triangular, square, polygonal, rectangular or in principle any shape.

List of reference symbols

10 Water treatment device

12 first exterior wall

14 first exterior wall

16 Base plate/floor

18 (first) reservoir

20 Raw water

22 Side wall

24 Interior

26 drops of water (pure water)

28 Sun

30 Solar radiation

32 Evaporation device

33 (first) section (of the evaporation device)

34 Transport position

36 Evaporation position

38 collection containers

40 second reservoir

42 second section (of the evaporation device)

44 second exterior wall

46 second exterior wall

48 second collecting container

50 Drain siphon

52 Bottle

54 tube/cup

56 inverted upper part (of the bottle)

58 fabric (for cooling)

60 cooling water collection tanks

62 Cover

64 Raw water drain pipe

66 T funnel

68 Clean water drain pipe

70 translucent pipe / translucent pipe section Recess (for plug-in function) Drain opening Additional section Insert

Claims

Patent claims

1. Solar-powered water treatment device (10) for treating raw water (20) into pure water, comprising at least one transparent or translucent outer wall (12, 14, 44, 46, 70) which encloses an interior space (24) in which a first reservoir (18) for receiving the raw water (20), a collecting container (38, 48) for receiving the pure water and an evaporation device (32) are arranged, wherein the evaporation device (32) has a transport layer (34), wherein a section (33) of the evaporation device (32) is arranged for immersion in the raw water (20).

2. Water treatment device according to claim 1, characterized in that the evaporation device (32) has an evaporation layer (36).

3. Water treatment device according to claim 1 or 2, characterized in that a second reservoir (40) is arranged in the interior (24), wherein a second portion (42) of the evaporation device (32) is arranged for immersion in the raw water (20) of the second reservoir (40).

4. Water treatment device according to claim 3, characterized in that the second reservoir (40) is arranged above or below the first reservoir (18).

5. Water treatment device according to one of the preceding subclaims, characterized in that the water treatment device has at least a first outer wall (12, 14) and a second outer wall (44, 46) arranged above the first outer wall.

6. Water treatment device according to claim 5, characterized in that the water treatment device has two vertically arranged first outer walls (12, 14), on which two second outer walls (44, 46) inclined relative to the vertical and inclined towards each other are supported to form a roof section.

7. Water treatment device according to claim 5 or 6, characterized in that at a transition between the first outer walls (12, 14) and the second outer walls (44, 46) at least one second collecting container (48) is arranged to receive the pure water condensing on the second outer walls (44, 46). Water treatment device according to claim 7, characterized in that a drain siphon (50) for intermittently emptying the second collecting container (48) is arranged on or in the second collecting container (48). Water treatment device according to claim 8, characterized in that the drain siphon (50) has a nozzle device which is directed towards one of the outer walls (12, 14, 44, 46). Water treatment device according to one of the preceding claims, characterized in that the transport layer (34) has a microfiber fabric or is formed by such a fabric and/or that the evaporation layer (36) has a fabric made of fibers, for example cotton fibers. Water treatment device according to one of the preceding claims, characterized in that the evaporation device (32) has a pipe section-like or cup-like base body which is at least partially covered by a transport layer (34) and an evaporation layer (36), wherein the transport layer (34) has a material, in particular a material with an increased capillary effect on water. Water treatment device according to claim 11, characterized in that the evaporation device (32) is inserted into a reservoir (18, 40). Water treatment device according to one of the preceding claims, characterized in that at least one of the outer walls (12, 14, 44, 46) is formed by a pipe section (70), in particular by a section of a body of a bottle (52). Water treatment device according to one of the preceding claims, characterized by a stackable insert for arrangement within the at least one outer wall (12, 14, 44, 46, 70), wherein the insert has a funnel (66) and an evaporation device (32) which together form a reservoir (18, 40), wherein a raw water drain pipe (64) is arranged for connection to other inserts and has a drain opening (74) through which the next insert can be supplied with raw water (20).

15. Water treatment device according to claim 14, characterized in that the reservoir (18, 40) is arranged for cooling a side wall (22) or an inner wall of the funnel (66).