MXPA97007818A - Sealing device for a fluid containing liquid, gas, and a particulate material as well as a cleaning device provided with it, and a method for cleaning water residues - Google Patents

Abstract

The present invention relates to a settling device (2) for a fluid containing liquid, gas and particulate material, which comprises: a settling chamber to be filled with this fluid, a liquid discharge element ( 15) for discharging liquid from the settlement chamber, and adapted near the water level (11), a supply element (7) for supplying the fluid at the bottom of the settlement chamber, a row of oblique caps (12; 112), each having a flange (14; 114) located opposite an open side directed downwards (13; 113), and extending in the longitudinal direction of the cover, the row of covers (12; 112; ) in the settlement chamber, and arranged in an overlapping and parallel configuration with its longitudinal axes in an angle with the horizontal, in such a way that the fluid supplied at the bottom of the settlement chamber flows obliquely upwards, forced along the the of the oblique caps (12; 112), while the gas bubbles contained therein are collected in the flanges (14; 114) of the oblique caps (12; 112), a gas discharge element (17; 117) to trap the gas collected in the flanges (14; 114) of the oblique caps (12; 112) and to discharge this trapped gas from the settlement chamber, characterized in that the gas discharge element comprises a collection cover ( 17; 117) which extends essentially horizontally through the flanges (14; 114) of the oblique caps (12; 112), and which is provided below the water level (1;

Description

SEALING DEVICE FOR AN FLUID CONTAINING LIQUID. GAS. AND A MATERIAL IN PART CULAS. AS WELL AS A CLEANING DEVICE PROVIDED WITH THE SAME. AND A METHOD TO CLEAN RESIDUAL WATERS Description The present invention relates to a settling device for a fluid containing liquid, gas, and a particulate material, which includes: a settling chamber to be filled with this fluid, and where it is adjusted , for catching the gas bubbles, at least one lid having a flange located opposite an open side facing down, - a liquid discharge element adapted near the water level of the flow, an element of its supply to supply the fluid at the bottom of the settling chamber, and a gas discharge element for discharging gas trapped under the lid from the settlement chamber. A settlement device of this kind is known from European Patent Numbers EP-A1-0, 244, 029 and EP-A1-0, 193,999. These publications describe covers that fit horizontally in an overlapped connection, and that are adapted to limit the upper edge of a fermentation chamber, to form a settling chamber above it. The lids trap gas bubbles rising from the fermentation chamber, while allowing the transfer of the remaining fluid in the upward direction between the lids. The gas bubble trap ensures that the fluid in the settling chamber is relatively still relative to the fluid in the fermentation chamber, the last fluid being in an el-motion state as a result of the gas bubbles that are elevating The fact that the fluid present in the settlement chamber is relatively still, means that the particles that are present in it, and that are taken from the fermentation chamber, can settle, and these particles can fall back between the caps until the fermentation chamber. However, the known settlement devices of these publications have the disadvantage that, when greater turbulences occur, the bubbles can easily pass between the caps, and then make their way to the settlement chamber, thus having an adverse effect about the settlement in the settlement chamber. The smallest gas bubbles, in particular, will easily slip between the lids. The object of the present invention is, among other things, to eliminate the aforementioned drawbacks. The primary object of the present invention is to provide a settling device in which a liquid, gas, and particulate material can be separated, so that, in the upper part of the settling device, a liquid is collected which is in largely free of particulate material, and also preferably of gas. This object is achieved according to the invention, by the fact that at least one cover with its longitudinal axis at an angle to the level of the water is arranged, in such a way that the fluid supplied at the bottom of the settlement chamber flows obliquely upwards, forced along the bottom of at least one lid, while the gas bubbles contained therein, are collected in the rim of at least one lid, and by the fact that the gas discharge element catches, below the water level, the gas collected in the rim of the at least one lid. Since the fluid is supplied to the bottom of the settling chamber, and the liquid is discharged into the upper part of the settling chamber, an upward flow of fluid will be generated in the settling chamber. The obliquely placed lids ensure that this upward flow follows an oblique course. During this upward oblique fluid flow, the gas bubbles present in it will rise, as a result of its ability to rise, more inclined than the rest of the fluid, and finally they will come into contact with the lid obliquely placed. The obliquely placed cap subsequently allows an additional upward gas flow in the direction of the cap flange. As the fluid flows obliquely upwards, the gas bubbles contained therein are collected in this manner in the rim of the lid. By trapping the gas collected in the rim of the lid below the water level, this gas is prevented from moving the fluid in the water level. The fluid in the upper part of the settling chamber will then be in a relatively still state, in such a way that the particles still contained in the fluid are deposited here more easily. By an obliquely placed lid, it is to be understood here a body whose longitudinal axis, for the purpose of oblique positioning, runs at an angle with the water level (or horizontal), and whose lower side, seen in a direction perpendicular to the axis longitudinal, the so-called transverse direction, for the purpose of forming a lid, in the same way runs at an angle with the water level (or horizontal). The rim of the lid, in this case, is located on the upper side of the lower side angled obliquely in the transverse direction. A further advantage of the settlement device according to the invention is that, under the obliquely placed lid, a laminar flow can be performed, which promotes the deposition of the particles contained in the fluid. This laminar flow can be realized particularly by the fact that the gas bubbles that alter the laminar flow, as described above, are separated from the fluid, and discharged separately. Here it is pointed out that the so-called oblique plate settlement devices are known from the prior art, where use is made of a number of flat plates placed obliquely in an overlapped connection. In these plates, the lower side, viewed in a direction perpendicular to the longitudinal axis (ie, in the direction of the transverse axis of the plate), runs parallel to the water level (or horizontal). These oblique plate settling devices are suitable for the treatment of fluids containing liquid and particles. If these fluids contain gas bubbles, however, these gas bubbles will give an additional movement to the fluid flowing along the plates, thereby discouraging the settling of the particles contained in these fluids, and altering any laminar flow.

According to a convenient embodiment, the settlement device according to the invention comprises a row containing a multiplicity of covers that are arranged in an oblique, overlapped, and parallel configuration. Then the fluid will be forced to flow upwards by means of the interspaces formed between the adjacent lapped covers. As a result of the multiplicity of caps, the gas contained in the fluid will come into contact more quickly with a plate, and subsequently it will be collected in a rim, in such a way that the altering influence of these gas bubbles on the deposit of particles, It will decline more quickly. The trap and discharge of gas collected in the flange can be performed in a variety of ways. For this purpose, use may be made, for example, of an inverted funnel shaped element adapted in the flange, on the inner side of the lid. The narrow outlet of the funnel can be connected in this case with a tube that extends, for example, obliquely upwards along the rim, in order to discharge the gas upwards by means of a separate conduit, thus preventing that the fluid is altered near the water level. In accordance with a convenient embodiment of the invention, the gas discharge element may comprise a collection tube extending in an essentially horizontal manner through the flanges, and which, on the inner side of the caps, close to flanges, is provided with gas inlets having, for example, elements in the form of an inverted funnel. According to another embodiment of a simple design, the gas discharge element may comprise a collection lid extending in an essentially horizontal manner through the flanges. This collection lid, which can be coupled with the oblique tops in terms of the shape, will generally have a smaller width than the obliquely adapted tops. An advantage of a horizontally extending collection tube or a collection lid, among other things, is that the collection tube or the collection lid can simultaneously serve for the suspension and the mutual positioning of the oblique caps in the camera. settlement. Where a collection cover is used that extends through the flanges, it is also possible to collect and discharge floatable particles in a simple manner. By means of the arrangement of the collection tube or the collection lid extending essentially horizontally, at a slight angle of inclination in relation to the level of the water or the horizontal, the discharge of the gas collected therein is promoted, and of any floating particles. The oblique caps of the settlement device according to the invention will generally be adapted at an angle of 30 ° to 80 ° with the horizontal. Preferably, this angle will measure from 55 ° to 65 °. If the angle is too large, the gas bubbles contained in the fluid will be insufficiently trapped by the caps. If the angle is too small, an upward flow is excessively prevented. The value that is admissible for this angle will depend largely on the conditions of the process and the composition of the fluid to be treated. It has been shown that an angle of about 55 ° to 65 °, such as, for example, an angle of about 60 °, produces good results under various process conditions, and with respect to various compositions of the fluid to be treated. According to a convenient embodiment, the lids have an essentially V-shape in their cross section, the angle between the legs of the V being able to measure from about 100 ° to 130 °, preferably from about 110 ° to 120 °. These V-shaped caps are simple to produce by means of two plates that are held together, or by a plate that is bent at an appropriate angle. A laminar flow can be made between the lids, where the particles present in the fluid can be easily settled, according to the invention, wherein the caps are adapted to mutual horizontal intervals of approximately 2 to 8 centimeters, preferably approximately 6 centimeters. The invention further relates to a purifier for, for example, the anaerobic purification of waste water, which comprises: a fermentation chamber, a settling device according to the invention, which is adapted above the fermentation chamber, a degassing chamber, which is located next to the settling device, and which is divided by a division into a relatively gas-rich first compartment, and a relatively gas-poor second compartment, both compartments interlacing at the upper side of the partition , and the degassing chamber provided with a gas discharge being here, the first gas-rich compartment being connected to the fermentation chamber, and the second gas-poor compartment opening to the bottom of the chamber. the settling chamber of the settling device, and a spacer element adapted between the fermentation chamber and the settling chamber of the settling device, whose separating element traps the gas bubbles rising in the fermentation chamber, and discharges them towards The first compartment of the gas collection chamber, and leads to the particles deposited in the settlement chamber back to the fermentation chamber. In the fermentation chamber there is sludge, which cleans the waste water supplied in an anaerobic environment towards the fermentation chamber. In this way, rising gas bubbles are produced, which establish the fluid in the fermentation chamber in a violent motion, over which particles of sludge and other particles swirl through the fluid. The gas bubbles are trapped by the separating element, and are conducted away from the first compartment of a degassing chamber linked to the fermentation chamber. The gas bubbles will rise in the first compartment, and, as a result of the high concentration of gas bubbles, produce an upward flow of the fluid in this first compartment. At the top of the degassing chamber, the gas can escape the fluid, and the larger floating particles will continue to float out of the fluid. The leaked gas and the floating particles can then be discharged, after which a fluid remains that is poorer in gas and in particles. This fluid, which is poorer in gas and in particles, is subsequently conducted forward by a second compartment, to reach the bottom of the settlement chamber of the settlement device. The fact that the fluid undergoes a downward movement as it is conducted through the second compartment, means that a portion of the gas bubbles that are still being transported, can flow back in the opposite direction, to escape the fluid in the upper part of the degassing chamber, and it can be unloaded. The fluid is subsequently conducted by the settlement device already described above, on which, the remaining gas can also escape, and the particles that are still present can be deposited out of the fluid. The deposited particles fall back to the bottom of the settlement device, and make their way over the separating element between the fermentation chamber and the settlement chamber. From here, the deposited particles can be led back to the fermentation chamber. Using this purifier, you can clean the wastewater very well, such as the residual water from breweries, for example, or the waste water that contains sludge. You can add different kinds of bacteria and supports for them to the fermentation chamber, depending on the kind of wastewater. Biomass and / or sludge can be placed in the fermentation chamber for the anaerobic or aerobic purification of waste water. In purifiers of this kind, the escaping gas will normally comprise 02, C02, H2, either alone or in combination with one another or with other gases. According to a very convenient embodiment, the separating element of the present invention comprises gas lids adapted in an essentially horizontal manner, which are disposed side by side, and in this way, they overlap a little with their lower ends, in such a way that there is a vertical gap between the lower ends of the adjacent gas caps, to make it possible for the particles. deposited in the settlement chamber are conducted back to the fermentation chamber. For gas caps, a large number of gas caps known from the prior art can be used. Particular reference should be made to gas caps adapted above a fermentation chamber, which are known from European Patent Applications Nos. EP-Al-0,193,999 and EP-A1-0, 244, 029 of the applicant, whose gas caps , when referenced as part of the present application, are incorporated herein. The invention further relates to a method for the anaerobic or aerobic purification of waste water, using a device according to the invention. The invention will be explained in more detail below with reference to the accompanying drawing. In this drawing, a purifier according to the invention is illustrated by way of example, wherein: Figure 1 shows a diagrammatic perspective view of a purifier according to the invention. Figure 2 shows a diagrammatic side view, partially broken away in parts, of Figure 1. Figure 3 shows a cross section according to lines III-III of Figure 2. Figure 4 shows a detail of Figure 1, wherein, however, the caps 12 are adapted in a different alternative way. Figure 5 shows a diagrammatic representation of the path covered by a gas bubble that rises in the settlement device. The figures show a cleaning device 1, according to the invention, more particularly provided with a seating device 2 according to the invention. The cleaning device comprises a reaction chamber, such as a fermentation chamber 3, above which a settling device 2 is adapted. The fermentation chamber 3 and the settling device 2 are separated from one another by means of the caps separators 4 (shown in a purely diagrammatic representation), as is known from European Patent Numbers EP-Al-0,244, 029 and EP-A1-0, 193, 999 (incorporated herein by reference). The cleaning device further comprises a degassing chamber 5 comprising a first compartment 6 and a second compartment 7, whose compartments are separated from each other by an oblique division 8. On the upper side of this division 8, the compartments 6 and 7 one inside the other. In the upper part of the degassing chamber 5, a gas discharge 9 and a spraying device 10 are provided for spraying water in order to release the gas bubbles attached to the floating particles, of said particles. In the upper part of the degassing chamber, at the water level 23, a discharge (not shown) for the floating particles is provided in the same way. The settling device 2 comprises a multiplicity of V-shaped caps 12, which are placed obliquely at an angle of 60 ° with the level of the water 11 of the fluid. Each cover 12 has an open side directed downwards 13, and an opposite flange 14. The angle β between the legs of the V-shaped lid measures here approximately 110 °. In the upper part of the settlement chamber of the settlement device, liquid discharge elements in the form of overflow holes 15 are adapted close to the level of the water 11 of the fluid. These overflow orifices 15 form a connection with a drainage 16. The horizontal interval Z between two adjacent oblique lids, here measures approximately 6 centimeters. The oblique lids 12 are placed one in relation to the other by means of a V-shaped collection lid 17 which extends in an essentially horizontal manner, and are suspended by means of those lids 17 in the settling chamber of the device. settlement. This collection lid 17 extends through the shoulders 14 of the row of successively mutually overlapping lids 12. Just below the rim of the collection lid 17, the passages 18 are formed in the flanges of the oblique lids 14 for the conduction of, in particular, the gaseous fluid. The collection lid 17 preferably slopes a little obliquely towards the degassing chamber 5, and opens towards the degassing chamber 5. The gases collected under the collection lid 17, and the floating particles, are then discharged from a automatically to the degassing chamber. In the illustrated example, the separating element 4 comprises an entire lid 30 and two half-tops 19 adapted next to the latter, and in a slightly overlapped configuration. The lower ends of the covers 30 and 19 are adjusted in such a way that they overlap so that a vertical recess 20 is formed here, which is delimited by the lower end of the cover 19 located above., and the upper face of the lid 18 located below. Through this gap 20, the particles and fluid can flow back into the fermentation chamber 3 below it. The purifier described above works, as a whole, as follows: Present in the fermentation chamber 3, for example, are biomass, bacteria, support material for these, sludge, and other particles. The waste water is supplied to the fermentation chamber by elements (not shown), preferably continuously. The waste water is cleaned by the bacteria and / or other means located in the fermentation chamber, thus generating gas, such as 02, C02, H2. This formation of gas establishes the fluid in the fermentation chamber in a violent movement, as a result of which, the particles located in the fermentation chamber begin to float around. The gas bubbles that are rising, are largely trapped by the caps of the separator element 4. As illustrated by the arrows 21 and 22, this trapped gas is conducted to the first compartment 6 of the degassing chamber 5. Here , the gas will rise further, thereby producing an upward flow of fluid. The fluid from the fermentation chamber 3 will consequently be guided upwards, over which, many particles contained in the fluid will be carried with it. The larger gas bubbles will leave the fluid in the upper part of the degassing chamber 5, and may be discharged by means of a gas discharge 9. The floatable particles that are carried along with the fluid out of the fermentation chamber 3 , they will end up floating above water level 23, at the top of the degassing chamber. These floating particles subsequently can be discharged, and the gas bubbles attached thereto can be released by means of the spraying device 10. As a result of the gas rising from the fermentation chamber and from the separating element 4, the fluid , as indicated by the arrow 24, it will also be transported obliquely downwards through the second compartment 7 to the bottom of the seating device 2. As it flows down through the second compartment, a portion of the gas still present in the fluid , it may rise as bubbles against the direction of flow, and be collected in the upper part of the degassing chamber 5, to then be discharged by means of a gas discharge 9. As represented by the arrows 25, at the bottom of the device 2, a portion of the fluid will flow back through the holes 20 to the fermentation chamber, the particles as deposited in the settlement device 2 to be carried with it. As represented by the arrows 26, another portion of the fluid will be forced to flow along the obliquely-adapted lids 12, after which, finally, at the top of the settling device, the fluid is discharged from the purifier by means of of the overflow orifices 15. During this upward forced flow of the fluid along the bottom of the obliquely-adapted lids 12, a laminar flow will be formed where the heavier particles still present in the fluid will be easily deposited. These gas bubbles that are still present in the fluid, and that alter the laminar flow, and the lighter floatable particles, will rise vertically, or in any case more inclined than the fluid itself, as a result of the lifting force towards above that is found by the same. These bubbles and the lighter particles are then forced to make contact with an oblique face of a cover, and will be led by this oblique of the cover in question, to the flange 14 of the cover in question. Along the inner side of this flange 14, the gas and lighter particles will then rise higher, until being caught by the adapted gas discharge element below the water level 11, in this case in the form of a collection lid adapted in an essentially horizontal manner 17. The gas and the lighter particles are collected in the lid collection 17, and flowing through the openings 18 along the bottom of the collection lid 17, to the degassing chamber 5, where the gas can be further discharged by means of the gas discharge 9, and the lighter particles by means of the discharge for these (not shown). The fluid above the collection lid 17 is virtually completely free of gas and lighter floatable particles, thus promoting the further settlement of the heavier particles still contained in the fluid. The uppermost layer of the fluid in the settlement device, i.e. the fluid layer located near the water level 11, will be very low in particles floating therethrough. This fluid, which is very low in particles, can be further discharged as purified fluid by means of the overflow orifices 15 and the discharge conduits 16. It will be clear that the settlement device according to the invention can be used in a variety in ways The use in relation to the purifier illustrated herein is very convenient, but by no means the only option of use. Additionally, it will be clear that the direction in which the lids 12 adapt obliquely may vary. That is, with reference to Figures 1 and 2, it is conceivable that the lids 12 may also tilt obliquely to the right (instead of obliquely to the left, as shown), either obliquely to the front, or obliquely to the side. later, while here there are also the variants between them. Figure 4 shows a design variant of the settlement device according to the invention. The difference with Figures 1 to 3 is essentially that the obliquely placed caps 12 of Figures 1 to 3, are rotated by 180 ° in relation to their obliquely running longitudinal axes, and in Figure 4, they are indicated as the caps 12 The lids 112 remain with their longitudinal side edges in a sealing configuration against the side walls 120 of the settling chamber 2. Each cover 112 comprises, as seen, two sides that open. downwards 113 and two flanges 114. In this case, the flanges 114 are located along the side walls 120 of the settling chamber. Instead of a V-shaped collection lid 17, in the case of each rim 114, there is provided an oblique plate running in an essentially horizontal manner 117, which is placed with its upper edge against the lateral wall 120 of the settling chamber 2. In the embodiment according to Figure 4, each lid (V-shaped) 112 thus forms two lids. Figure 5 shows, with reference to a detail of Figure 4, the course of a gas bubble in the settlement device according to the invention. In zone 121, the gas bubble rises in an essentially vertical manner, until the gas bubble comes into contact with the lid 112. In zone 122, the gas bubble is then driven along the bottom from the lid 112 to the rim 114, having reached the rim 114, the gas bubble is conducted along the bottom of the rim 114 to the collection lid 117 (area 123), to be subsequently discharged by means of the collection cap 117 (zone 124).

Claims (13)

NOVELTY OF THE INVENTION Having described the above invention, it is considered as a novelty, and therefore, the content of the following is claimed as property: CLAIMS

1. A settling device (2) for a fluid containing liquid, gas, and particulate material, which comprises: a settling chamber to be filled with this fluid, a liquid discharge element (15) for discharging liquid from the settlement chamber, and adapted near the water level (11), a supply element (7) for supplying the fluid at the bottom of the settlement chamber, - a row of oblique caps (12; 112), having each, a flange (14; 114) located opposite an open side directed downwards (13; 113), and extending in the longitudinal direction of the cover, the row of covers (12; 112) adapting to the chamber of settling, and being arranged in an overlapping and parallel configuration with its longitudinal axes at an angle with the horizontal, such that the fluid supplied at the bottom of the settling chamber flows obliquely upwards, forced along the underside of the setter. the top s oblique (12; 112), while the gas bubbles contained therein are collected at the flanges (14; 114) of the oblique caps (12; 112), a gas discharge element (17; 117) to trap the gas collected at the flanges (14; 114) of the oblique caps (12; 112), and discharge this gas trapped from the settlement chamber, characterized in that the gas discharge element comprises a collection cover (17; 117) extending from an essentially horizontal way through the flanges (14; 114) of the oblique caps (12; 112), and which is provided below the water level (11).

2. A settlement device according to claim 1, characterized in that the collection cover (17; 117) is arranged at a slight angle of inclination in relation to the horizontal.

3. A settlement device according to claim 1 or 2, characterized in that the oblique caps (12; 112) are suspended in the settlement chamber, and placed one in relation to the other by means of the cap of collection (17; ll7).

4. A settling device according to claim 1, characterized in that on the shoulders (14; 114) of each oblique cover (12; 112), a passage (18; 118) is formed just below the rim of the rim. the collection lid (17; 117).

5. A settlement device according to claim 1, characterized in that the oblique caps (12; 112) extend up to the water level (11).

6. A settling device (2) according to claim 1, characterized in that the oblique caps (12; 112) are adapted to mutual horizontal intervals Z of 2 to 8 centimeters, preferably of approximately 6 centimeters.

7. A settling device (2) according to claim one of the preceding claims, characterized in that the oblique caps (12; 112) are adapted at an angle of 30 ° to 80 ° with the horizontal, preferably in a angle of 55 ° to 65 °, for example, 60 °.

8. A settling device (2) according to claim one of the preceding claims, characterized in that the oblique caps (12) have a substantially V-shaped cross section, being able to measure the angle ß between the legs of the V from about 100 ° to 130 °, preferably from about 110 ° to 120 °.

9. A purifier (1) for, for example, aerobic or anaerobic purification of waste water, which comprises: - a reaction chamber (3), such as a fermentation chamber, a settling device (2) in accordance with what is claimed in one of the preceding claims, which fits above the reaction chamber (3), a degassing chamber (5), which is located next to the settling device (2), and which is divided by a division (8) in a first compartment relatively rich in gas (6), and a second compartment relatively gas-poor (7), both compartments being interlaced on the upper side of the division (8), and the degassing chamber (5) provided with a gas discharge (9) being here, the first compartment being gas-rich ( 6) linked to the fermentation chamber, and the second gas-poor compartment (7) opening towards the bottom of the settlement chamber of the settlement device (2), and a separating element (4) adapted between the reaction chamber ( 3) and the settling chamber of the seating device (2), which separating member (4) trap gas bubbles rising in the reaction chamber (3), and discharges into the first compartment (6) of the pickup camera n of gas (5), and conducts the particles deposited in the settling chamber back to the reaction chamber (3).

10. A purifier according to claim 9, characterized in that the separating element (4) comprises gas flaps adapted in an essentially horizontal manner (19, 30), whose gas flaps (19.30) are arranged side on the side, and in such a way that they overlap a little with their lower ends, such that there is a vertical gap (20) between the lower ends of the adjacent gas caps (19, 30), to enable the particles deposited in the settlement chamber, drive back to the reaction chamber (3).

11. A purifier according to claim 9 or claim 10, characterized in that the collection lid (17); 117) is configured with one of its ends extending to the degassing chamber (5).

12. The use of a settling or purifying device according to claim 1 of claim 1 to 8, respectively 9 to 11, for the anaerobic purification of wastewater.

13. The use of a settling device according to claim 1 or more of claims 1 to 8, for the separation of a fluid containing liquid, gas, and particulate material, wherein the particulate material comprises more floating particles. light. SUMMARY OF THE INVENTION The present invention relates to a settling device (2) for a fluid containing liquid, gas, and particulate material. The device (2) comprises a liquid discharge element (15) adapted near the water level of the fluid, and a supply element for supplying the fluid at the bottom of the settling chamber. In the settlement chamber, one or more covers (12) are arranged with their longitudinal axis at an angle with the water level, such that the fluid supplied at the bottom of the settlement chamber flows obliquely upwards, forced to along the bottom of the at least one lid. While the gas bubbles contained in it, are collected in the flange (17) of the at least one lid. The gas collected in the rim of the at least one cap is trapped by a gas discharge element (18) below the fluid water level. Preferably, use is made of a row containing a multiplicity of lids (12) that are arranged in an oblique, overlapped and parallel configuration. The caps (12) can be adapted at an angle of 60 ° relative to the water level, and preferably have a mutual interval of about 6 centimeters. The invention further relates to a purifier provided with a settling device of this kind, and to a method for the anaerobic purification of waste water using a settling or purifying device according to the invention. * * * * *