EP0588842A1

EP0588842A1 - Fixed-bed reactor for the biological treatment of sewage

Info

Publication number: EP0588842A1
Application number: EP92911172A
Authority: EP
Inventors: Walter Rausch
Original assignee: Mesroc Vertrieb Technischer Produkte GmbH
Current assignee: Mesroc Vertrieb Technischer Produkte GmbH
Priority date: 1991-06-08
Filing date: 1992-06-05
Publication date: 1994-03-30
Also published as: JPH06509973A; DE4118927A1; WO1992022505A1; DE4118927C2

Abstract

Réacteur à lit fixe comportant au moins deux étages pour le traitement biologique des eaux usées, ce réacteur étant un récipient contenant un support fixe pour micro-organismes, le liquide à purifier circulant autour de ce support. Ledit support est constitué d'éléments plats, rectilignes, recourbés ou tubulaires et le sens de l'écoulement du liquide est parallèle aux plus grandes surfaces des éléments.Fixed bed reactor comprising at least two stages for the biological treatment of waste water, this reactor being a container containing a fixed support for microorganisms, the liquid to be purified circulating around this support. Said support consists of flat, rectilinear, curved or tubular elements and the direction of flow of the liquid is parallel to the largest surfaces of the elements.

Description

description

Fixed bed reactor for the biological treatment of waste water

The invention relates to a fixed bed reactor with at least two stages for the biological treatment of waste water according to the preamble of claim 1.

It is known that the microbial turnover in biological processes is more efficient if the microorganisms involved do not swim freely around, but are fixed on carrier materials and can form colonies there. A number of different carrier materials are also known, e.g. porous sintered glass, highly porous materials such as diathomeric earth or lava stone, synthetic foam and sintered, porous thermoplastic. Depending on their properties, these carriers can be used with regular and irregular shapes both in the fixed bed process and in the fluidized bed.

However, it has proven to be disadvantageous that when such carrier materials are used in a fixed bed, for example in the form of irregularly poured pipe sections, the biosludge which arises with each microbial material conversion gradually fills up small gaps, thereby making the flow more difficult and also not available for material conversion stands. Another disadvantage of poured carrier elements is the inconsistent flow, which can be further deteriorated by the possibility of segregation of larger and smaller elements. The object of the present invention is therefore to provide a fixed bed reactor in which the resulting bio-sludge does not cause blockages and is available to the greatest extent possible for a material conversion and in which the carrier material is arranged in such a way that a uniform flow around the largest possible area of the Carrier material is made possible.

This object is achieved with the features mentioned in the characterizing part of claim 1.

Special embodiments and developments of the invention are included in the further claims.

According to the invention, flat, curved, straight or tubular support elements are used in the fixed bed reactor in such a way that the direction of flow of the liquid to be cleaned is parallel to the large areas of the support elements.

Such support elements can e.g. Plates or tubes made of a porous sintered plastic material, in which coarser, very fine-pored grains of activated carbon or Liapor, partially open to the surface, are advantageously enclosed. The plates or pipes can be flat elements or profiled, e.g. wavy or trapezoidal, body.

In one embodiment of the invention, several plates are arranged parallel to one another and fill the entire reactor cross section. On the one hand, the size of the distance between the plates should be as small as possible in order to have the largest possible exchange area in the To be able to accommodate the reactor. On the other hand, it must not fall below a minimum value in order to avoid the risk of constipation. The optimization of the minimum column width depends on the mycelium formation of the microorganisms used in each case and can be determined experimentally. The type of microorganisms is determined by the pollutant content of the substrate to be cleaned. The optimization of the minimum column width also includes that the column width across the cross-section is the same everywhere, otherwise the flow resistance in the columns would be different, which would result in an uneven flow through the reactor cross-section and thus an uneven material conversion.

In another embodiment of the invention, the plates are arranged in a ring, the rings formed in this way having a different diameter and being arranged coaxially one inside the other at equal intervals.

In a further embodiment of the invention, the carrier elements are tubes of different diameters, which are arranged concentrically one inside the other.

The arrangement of the gaps in the form of coaxial rings or tubes or parallel plates is equally possible according to the invention. The decisive factor for the optimization is the available outer plate exchange surface, which is the one for the

Overall effectiveness of the mass transfer effective pore surface is directly proportional. For example, a reactor with an inner diameter of 1.2 m, a plate thickness of 18 mm, a column width a = 15 mm, as is favorable for brewery wastewater, and one Plate height of 0.3 m, the outer exchange surface for concentric rings 20 m ² , for parallel, straight plates 19 m ² , provided that the effective surface of the plates is 2.7 times larger than that of a flat plate of the same dimensions due to structuring.

If one considers the flow rate or dwell time of the substrate, which is necessary for the biological anaerobic degradation, then on the one hand one finds very long times in relation to the reactor height and on the other hand very low flow rates. For the above example, this results in a speed in the order of magnitude v = 10 ° m / s. The Reynold number calculated here is approximately 1.0, which clearly indicates a purely laminar flow form.

The characteristic of the laminar flow form is the absence of the macroscopic exchange processes in the fluid transversely to the flow direction, which in turn means that the metabolism by the microorganisms only in the immediate carrier elements, i.e. Plate surface takes place where the liquid comes into contact with the microorganisms. An economical reactor design therefore makes it necessary to mix the liquid as often as possible in order to gradually bring all pollutant components into contact with the microorganisms.

According to the invention, it is proposed for this purpose to arrange a plurality of carrier packs, each consisting of a plurality of carrier elements, ie plates, one behind the other, as viewed in the direction of flow, the plates of two successive carrier packs advantageously being arranged with respect to one another in such a way that one plate stands above a gap or vice versa. A similar effect is achieved in that in the case of carrier packages made of straight, parallel plates, the packages are offset from one another by an angle of, for example, 30 °.

It has proven to be advantageous to keep the height of the carrier packages as small as possible, for example the ratio of the reactor diameter to the height of the carrier packages can be 4: 1.

To extend the residence time or to reduce the reactor height, it is advantageous to design the reactor in a loop arrangement, i.e. to allow multiple flow through the carrier packages by pumping. The liquid is sucked off behind the individual loop stages and fed back to the beginning of the loop. The liquid withdrawn from the previous stage, or the newly supplied liquid, and the liquid fed back from the subsequent stage come into contact with one another and mix. This mixing becomes particularly intense when the discharge of the previous stage is behind the supply of the following stage and the outlet direction of the liquid is downwards, i.e. in the direction of flow. takes place against the main flow direction.

Another advantage of the multiple loop arrangement can be seen in an improvement in the controllability or the uniformity of the pH in the reactor. It can happen that the pH setpoint deviates from the permissible range (eg +/- 0.5) at one point of the reactor and requires an acid or alkali metering to compensate. With only one The system becomes sluggish the longer the controlled system is, the larger the reactor volume for a given flow rate. Large fluctuations around the setpoint and long control times are inevitable. The subdivision of the reactor volume into several small sub-areas, ie stages with successive carrier packs, with their own pumping facility, makes fast regulation possible, which can also start at the sub-area where the deviation is detected. For this purpose, each sub-area has its own pH measuring point. A

The control loops can be cascaded with the same aim of more quickly correcting the fault.

Crucial for an economical reactor operation is an even distribution of the polluted liquid over the cross section of the reactor in order to achieve an optimal degradation rate of the pollutant. The distribution becomes more uniform the more inlet openings are regularly distributed over the cross section of the reactor. It is advantageous to adapt this arrangement to the reactor cross-section, i.e. In the case of circular reactor cross sections, the number of inlet openings should be arranged as evenly as possible on concentric circles. Also the

Mixing becomes more intensive, the more inlet openings are present and if this results in a relatively small amount of liquid tearing a larger amount of liquid into a free jet than a larger outlet speed. In addition, since almost all free jets are turbulent, the desired mixing and uniform distribution is further favored. The radiation flow in the free jet is related to the vertical flow of a baffle plate or the Flow around rotationally symmetrical profiles, both of which can be used in the reactor according to the invention.

The invention is described in more detail below with reference to drawings. Show:

1) a carrier package according to the invention;

Fig. 2) a section to Fig. 1;

3) a schematic representation of a fixed bed reactor according to the invention;

4) an arrangement for supplying liquid;

Fig. 5) is a schematic representation of a

Liquid outlet with baffle plate;

Fig. 6) a profiled plate as a carrier element.

The carrier package according to the invention according to FIGS. 1 and 2 consists of tubular carrier elements 1 of different diameters, which are arranged concentrically one inside the other. The carrier elements 1 are fastened on connecting webs 3 of two annular disks 2a, 2b and are stretched between these disks 2a, 2b. At their ends, the support elements are held in sockets 4a, 4b, which are screwed, glued or welded onto the connecting webs. The annular disks 2a, 2b are detachably connected to one another with threaded rods 5a and screws 5b. In the connecting webs 3, threaded bores 6 are made in the center of the carrier package, into which threaded rods 7 are screwed for introducing the carrier packages into the reactor can. In order to attach the carrier packs to the inner wall of the reactor, claws or blocks are each arranged at the same height, on which the lower annular disk 2b rests. In order to be able to guide the carrier packs past claws or rows of blocks when a plurality of carrier packs are to be fitted in the reactor, the annular disks 2a, 2b are provided with recesses 8 lying one above the other, which are dimensioned such that they fit over the claws or blocks . If the intended row of claws or blocks is reached, a small turn is sufficient to leave the carrier package on. Due to their own weight and the low flow, it is normally not necessary to attach the carrier packs further, however, if necessary, they can be screwed onto the claws or blocks, for example.

3 consists of a plurality of carrier packs 10, which are arranged in a reactor housing 9 at a distance from one another and are arranged between the reactor inlet 12 and outlet 13, as described in more detail in relation to FIGS. 1 and 2, on the inner wall of the reactor fixed claws 11 rest. Each level, i.e. after each carrier package 10, a pump device 14 is assigned, which sucks off part of the liquid, which emerges from a carrier package 10 and supplies this part of the liquid to the reactor below this carrier package 10 again. The loops formed in this way can include one or more carrier packs 10. In the area of

Baffle plates 15 are arranged for better mixing of the different streams, reactor inlet 12, in which liquid from stages located further up is also returned. In this schematic representation, the support elements 1 and the columns arranged between them one above the other. As stated above, however, it is advantageous to provide an offset here.

FIG. 4 shows a liquid supply which can be connected to one of the pump devices mentioned in FIG. 3. This liquid supply consists of an inlet pipe 20, which is connected to a ring line 21, from which branch lines 22, 22 ′ of inward length are directed. The branch lines 22, 22 'have at their ends fork-shaped pipe sections 23, 23', at the ends of which in turn there are inlet openings 24 for the liquid. The branch lines 22, 22 'and the pipe sections 23, 23' are arranged so that the inlet openings 24 lie on two or more of the concentric circles presented. The same amount of water should advantageously exit at each opening 24. Instead of via a ring line 21, the individual branch lines can also each be connected directly to pump devices.

As outlined in FIG. 5, the inlet openings 24 point downward, with a baffle plate flowing vertically at a distance of, for example, 10 mm from them. As a result of the flow around the pipe profiles of the branch lines 22, 22 'and the pipe sections 23, 23' and through the processes of beam spreading, the ascending beam widens in the direction of the next carrier package. The beams, which widen up next to each other, should at least touch or overlap when the carrier package is reached. 6 finally shows a section of a profiled carrier element 30 which is inserted or cast into guides 31 at the ends. To increase the surface area, the carrier element has trapezoidal structures 32.

Claims

Expectations

1. Fixed bed reactor with at least two stages for the biological treatment of waste water, the reactor being a container which contains a carrier material for microorganisms fixedly arranged therein, this carrier material being flowed around by the liquid to be cleaned, characterized in that the carrier material consists of flat, straight , curved or tubular support elements (1) and that the flow direction is parallel to the large areas of the support elements (1).

2. Fixed bed reactor according to claim 2, that the support elements (1) are arranged in a ring, the rings having different diameters and being arranged coaxially one inside the other.

3. Fixed bed reactor according to claim 1, so that the carrier elements (1) are tubular, have a different diameter and are arranged concentrically one inside the other.

4. Fixed bed reactor according to claim 1, 2 or 3, characterized in that a plurality of carrier elements (1) form a carrier package (10), and that carrier packs (10) are arranged in the at least two successive, connected stages.

5. Fixed bed reactor according to claim 4, d a d u r c h g e k e n n e e c h n e t that the carrier packages (10) are arranged one above the other in such a way that there are plates over columns or vice versa.

6. Fixed bed reactor according to claim 4, so that the carrier packs (10) consist of plates arranged in parallel to one another and that each carrier pack (10) is offset by an angle from the next one.

7. Fixed-bed reactor according to claim 6, that the offset of the carrier packs (10) to each other is 30 ° in each case.

8. Fixed bed tractor according to claim 4, characterized in that the flow rate, determinable between the reactor inlet and outlet (12, 13) by loop-like intermediate suction and re-supply between the individual carrier packages (10) one or more times in succession, a further flow component is superimposed a freely selectable speed and residence time in the reactor in the spaces between the support elements (1) enables.

9. fixed-bed reactor according to claim 8, d a d u r c h g e k e n n e e c h n e t that the suction openings of the subsequent stage in the flow direction seen behind the inlet openings of the previous stage in the loop-like suction.

10. Fixed bed reactor according to claim 1, d a d u r c h g e k e n n z e i c h n e t that a pH measuring point is assigned to each stage.

11. Fixed bed reactor according to claim 1, so that the amount of liquid to be distributed uniformly over the reactor cross-section is distributed by regularly over the reactor cross-section and downwards, i.e. inlet openings (24) directed opposite to the main flow direction.

12. Fixed bed reactor according to claim 11, d a d u r c h g e k e n n z e i c h n e t that baffles (15) are placed in front of the inlet openings (24).

13. Fixed bed reactor according to claim 4, characterized in that the carrier elements (10) are gripped at two clamping ends and these sockets (4a, 4b) are each connected with annular disks (2a, 2b), which in turn are screwed together by means of threaded rods (5a) to form a carrier package (10).

14. Fixed bed reactor according to claim 13, d a d u r c h g e k e n n e e c h n e t, 10. that the carrier packages (10) are each inserted into the reactor by means of a threaded rod (7) screwable in the axis of the carrier packages (10).

5 15. fixed bed reactor according to claim 13, d a d u r c h g e k e n n z e i c h n e that the carrier elements (1) consist of a material which is poured into the sockets (4a, 4b).