AU611776B2

AU611776B2 - Contact material and manufacture thereof

Info

Publication number: AU611776B2
Application number: AU31052/89A
Authority: AU
Inventors: Hartwig Basse; Jurgen Wittek
Original assignee: Norddeutsche Seekabelwerke GmbH
Current assignee: Norddeutsche Seekabelwerke GmbH
Priority date: 1988-03-09
Filing date: 1989-03-06
Publication date: 1991-06-20
Anticipated expiration: 2009-03-06
Also published as: ATE76041T1; DK113589A; NO179280C; FI100522B; AU3105289A; NO890918D0; FI890956A0; FI890956A; ES2032064T3; DE58901362D1; NO179280B; NO890918L; DK174626B1; DK113589D0; NZ228257A

Abstract

A filler and a process for producing it, where the filler, in the case of the biological treatment of sewage, should in particular exhibit a "biological meadow" which is necessary for this purpose, and a uniform moistening ability. In the case of known fillers which consist of strips, it has been found that the strips straighten under influence of encrustation and thereby form a pore foothold for the "biological meadow" and seek to become attached to each other. The purpose of the novel filler is to eliminate this drawback, and for it to be easy to manufacture and install. The novel filler exhibits at least one tensile member (fibre 29), which has been located beside the strips 20. When suspended, this takes up the load such that the strips 20 are essentially unloaded and thereby retain the shape they were given during manufacture. The filler is especially suitable for the biological treatment of sewage and drinking water, i.e. denitrification. <IMAGE>

Description

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COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952 Form COMPLETE SPECIFICATION FOR OFFICE USE Short Title: Int. Cl: 611776 Application Number: Lodged: Complete Specification-Lodged: Accepted: Lapsed: Published: Priority: Related Art: III. a TO BE COMPLETED BY APPLICANT a, i I Name of Applicant: Address of Applicant: Actual Inventor: Address for Service: NORDDEUTSCHE SEEKABELWERKE

AKTIENGESELLSCHAFT

Kabelstrasse D-2890 Nordenham 1, WEST

GERMANY

HARTWIG BASSE and JURGEN WITTEK GRIFFITH HACK CO.

71 YORK STREET SYDNEY NSW 2000

AUSTRALIA

Complete Specification for the invention entitled: "CONTACT MATERIAL AND MANUFACTURE

THEREOF"

The following statement is a full description of this invention, including the best method of performing it known to us:- 8143A/bm 1 LiE 9 .i p1 8143A/bm IA9- Contact material and manufacture thereof Description The present invention relates to a plastics contact material for treating liquids. The present invention further relates to a process for manufacturing contact material for biological water treatment.

The contact material in question here is utilized in particular for biological truatnent in the water industry. In this use, the contact material serv-es as a support material for the bacteria required for the biological treatment, i.e. as a support material for a so-called biological lawn. The utility of a water treat- :ment plant equipped with such a contact material depends on several factors. On the one hand, the contact material should provide a very large specific growth area, while on the other hand good adhesion of the bacteria to the contact material is very important. Finally, the biological lawn on the contact material should be easily permeable or wettable by the liquid to be treated.

The known contact material of the type classified in the preamble, i.e. a contact material made of a 30 plurality of plastics strips, has the disadvantage that Se:. the smooth strips tend to stick to one another, as a result of which the liquid to be treated is no longer able to flow through between the biological lawn of 4 adjacent strips, appreciably reducing the effectiveness of a water treatment plant equipped therewith. As a remedy it has been tried to use strips having an see irregular, predominantly crimped surface. However, it was found that, as a consequence of the weight on the strips due to the biological lawn growing thereon, even previously crimped strips become smooth in time with the -2consequence that even they gradually become stuck together.

In addition, it proved expensive to form the known striplike contact material into trickling filters, since it is very difficult to suspend the strips from an appropriate carrying means in uniform distribution over the entire trickling filter required for optimum performance.

Against this background, the present invention has for its object to provide an effective and easily mountable striplike contact material and a process for a simple manufacture thereof.

According to the present invention there is provided a plastics contact material for biological treatment of water, comprising a plurality of strips made of a plastics material, wherein on each strip at least one tension-absorbing strand is arranged which substantially prevents the associated strip from stretching.

Advantageously, the tension element is constructed as a tension-absorbing strand extending in the 2 longitudinal direction of the strip. This strand is easy to 20 manufacture and has virtually no impairing effect on the se* .o growth of the strips.

It has proved particularly advantageous to assign to each strip a single strand. The strips thus reinforced curl under a load around the strand which thus forms, as it were, a longitudinal central axis of a spiral.

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ee 0 SS SR In a refinement of the contact material it is proposed to provide the areas between adjacent strips that border on the holding web with clearances. These clearances can be brought about when the adjacent strips have a narrower width along the length of the clearances.

The clearances -have the function in the contact material, customarily laid with the holding web and downwardly extending strips across a support bar, to guide the dirty water, applied from above to the holding bar or web, toward all sides of the strips for uniform wetting thereof.

Finally, according to a further proposal of the invention, the contact material is refined to the extent that a plurality of holding webs with strips arranged thereon are gathered together on top of one another in such a way that the holding webs and only the holding webs are connected to one another. The strips of the individual superposed layers are thus not connected and thus can be wetted from all sides. In such a contact bed, a relatively large number of strips can be joined together to form a one-piece unit which can be suspended from a supporting frame as a whole. This makes it possible to obtain high assembly efficiency.

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0 It is further proposed according to the invention to seal a plurality of strands simultaneously onto a web serving to form a comparatively large number of side by side strips, and after the strands have cooled down, to divide the web by. means of progressive separating cuts between two adjacent strands to form side by side strips.

This process permits a high fabrication capacity since a plurality of side by side strips can be manufactured at the same time.

It is further proposed to form the holding web serving to join together side by side strips by suspending the separating cuts to form side by side strips from the web at regular intervals. The holding strips are thus formed very simply by leaving the web used for forming the strips unchanged in the areas of the holding strips.

This is thus an essential simplification of the manufacture of the contact material according to the invention.

Finally, it is also proposed for the process that to create a larger handling unit comprising a relatively large number of independent strips a plurality of webs are gathered together. To this end, a plurality of webs are brought together and, after the individual strips

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0.0 1 /e rr have been cut, are bonded together at their holding strips, preferably by welding. In this way it is possible to gather together an appreciable number of strips and to mount them as a whole on a supporting frame or the like of the trickling filter.

A preferred embodiment of the present invention will now be described by way of example only with reference to the accompanying drawings.

Figure 1 shows a detail of a trickling filter comprising a contact material hung over a supporting frame, Figure 2 shows a plan view of the contact material according to Figure 1, Figure 3 shows a magnified two-dimensional view of a section of-a single strip of contact material, Figure 4 shows a cross-section through the strip according to Figure 3, o tFigure 5 shows a side view of the strip according 0 to Figure 3, Figure 6 shows a plan view of a further illustrative embodiment of the contact material, Figure 7 shows a magnified two-dimensional view .of a section of a strip of the contact material of Figure *25 6, Figure 8 shows a side view of the strip according to Figure 7, Figure 9 shows an apparatus for applying strands to a web of material serving to form a plurality of :30 strips, 6. 5 Figure 10 shows an apparatus for cutting the strips out of the web of material and for bringing together a plurality of superposed webs and Figure 11 shows an alternative illustrative 35 embodiment of the apparatus according to Figure 10 for .manufacturing strips according to the illustrative embodiment of Figures 6 to 8.

The contact material shown in the illustrative embodiments serves as a trickling filter for biological LB! n n ii 6 water treatment.

Figs. 1 to 8 show embodiments of contact material where a plurality of side by side, elongated strips are connected to one another by a central, transversely extending holding web 21. Individual strips 20 of the contact material here are arranged in three superposed layers 22 and 23. As Figure 2 shows, the two outer layers 22 have the same number of strips 20. Similarly, the arrangement of the strips present in the outer layers 22 is approximately the same. By contrast, the central layer 23 has one strip 20 fewer. As a result, the strips 20 of the central layer 23 can be arranged offset relative to those of the two outer layers 22 in such a way that the strips of the central layer 23 come to lie centrally S. 15 between two strips 20 of the outer layers 22, i.e.

opposite a gap. The length of the strips 20 is approximately the same in every layer 22 or 23.

L eO As can be seen from Figure 2, the strips situated at opposite end areas 24 and 25 of the holding 20 web are integrally connected to the holding web. To this end, the holding web 21 and the strips 20 associated therewith are made of a common web of material 26 which, in the areas bordering the holding web 21, is provided with continuous incisions 27 to form the strips

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Accordingly, the side by side strips 20 are separated •es from each other in each case by an incision 27 which extends continuously from the free ends 28 of the strips to the respective end area 24 or 25 of the holding web 21.

In the present illustrative embodiment, as can be seen in Figures 1 to 5, each strip 20 has associated with it a tension element, namely a strand 29. As can be seen in particular in Figure 2, in each case one straight strand extends from the free end 28 of a strip 20 situated on one side of the holding web 11 to the (opposite) free end 28 of a strip situated on the other side of the holding web 21. One strand 29 thus joins together two opposite strips 20 by extending uninterruptedly transversely across the holding web 21. The arrangement of the -7strands 29 is such that they are situated on one side in the middle of the strips. This can be seen clearly in Figure 4. As can again be seen in Figure 2, each of the layers 22 and 23 has as many parallel strands 29 as they have side by side strips As can further be seen from Figure 2, but also from Figure 1, (end) areas of the strips 20 that are oriented toward the holding web 21 have been provided with incisions 30, which are approximately rectangular and are each situated between two adjacent strips 20, as a result of which the strips 20 have a reduced width in the areas of the incisions 30, without, however, interrupting the strands 29. The purpose of the incisions is to ensure that, when in the suspended state on a 15 supporting bar 31 of a supporting frame 32, the liquid trickled downward onto the trickling filter can get to °the strips 20 of the central layer 23 and to the outer 0ee* layer 22 oriented toward the supporting bar 31, i.e. to ensure uniform wetting of the strips 20 of all the layers 0 20 22 and 23.

As can also be seen in Figure 1, the different layers 22 and 23 are bonded to one another in the central 0000 area of their holding webs 21 by a weld seam 33 which extends in the longitudinal direction of the holding web 21 and transversely to the strips.

It is evident from Figures 3 to 5 that, in 0 contradistinction from the strand 29, which extends in an approximately straight line, the strip 20 has been crimped, the type of crimp being such that it possesses 0000 folds 34 which extend transversely to the longitudinal direction. The parallel edges 35 of the strip 20 therefore show a degree of undulation, as can be seen particularly clearly in Figure 5, which gradually decreases from the edges 35 to the (central) strand 29. By virtue of this configuration the strip 20 has conferred upon it a three-dimensional structure which is an optimal surface for the "biological lawn" to be grown thereon for biological water treatment.

In the illustrative embodiment shown, the strand -8- 29 had an approximately circular cross-section whose diameter is appreciably greater than the thickness of the material of the strip. A suitable material for the strand 29 is a thermoplastic of low extensibility, for example polypropylene or polyethylene. As a result, and supported by the strand 29, the strip retains its length in the weighted state, i.e. when bearing the "biological lawn" growing on the surface of the strip 20, to a substantial extent and is prevented from becoming smooth, in particular at its wavy edges In contradistinction from the contact material described in Figures 1 to 5, the contact material shown in Figures 5 to 7 is made up of strips 36 which, seen in plan view, extend in snakelike fashion, namely sinusoid- S. 15 ally. These strips 36, as shown in Figures 5 to 7, can Soalso be provided on one side with a strand 37 which here extends in a straight line. To this end, the strip 36 in 0*@O the present illustrative embodiment extends alternately to one side or to the other side of the (straight) line 37, ensuring constant contact of the strip 36 with the strand 37. Alternatively, it is also possible to have the strand follow the snakelike line of the strip, in which o case the strand then also extends in snakelike fashion.

As can be seen in Fig. 8, the parallel snaky edges 38 of the strip 36 in the illustrative embodiment shown are crimped, so that they too have a wavy appearance. Such a strip 36 has a large spatial extension, providing particularly large growth areas for the "biological lawn". Alternatively, with the snakelike strips 36 shown here it is conceivable to dispense with the corresponding strands 37.

An apparatus for manufacturing the strands 29 and bonding the same to a web of material 26 for forming the strips 20 is shown in Figure 9. In the apparatus shown, a plurality of spaced-apart side by side strands 29 are produced by an extruder 39. The strands 29 emerging from a mouthpiece 40 of the extruder 39 are still hot, i.e. at a point immediately downstream of the mouthpiece 40, when they are brought together with the cold web of material I 9 26 and welded or sealed together therewith. To this end, the web of material 26 is taken off a stock reel 41 and guided between appropriate pairs of rolls, namely three pairs of rolls 42 in the present illustrative embodiment, through which the still hot strands 29 emerging from the mouthpiece 40 of the extruder 39 also pass. In the course of the strands 29 and the web of material 26 being passed through the pairs of rolls 42 the strands 29 are welded to the web of material.

Downstream of the pairs of rolls 42, the web of material 26 provided with the strands 29 is guided through a cooling station 43. This cooling station 43 has a plurality of support rollers 44 bearing against the underside of the web of material 26 and a cooling means S 15 45 coordinated with the opposite top side of the web of e° material 26 on which the strands 29 are situated. In the course of the cooling taking place in the cooling station 4*9@ 43, the strands 29 undergo shrinking and the cold, i.e.

nonshrinking web of material 26, is drawn together, as a 20 result of which it undergoes crimping, in particular at the edges Downstream of the cooling station 43, the crimped web of material 26 thus provided with the strands 29 is 'wound up on an intermediary storage reel 46. The web of material 26 thus prepared can then be further processed S. in the apparatus shown in Figure 10 to form the final contact material.

In the illustrative embodiment of Figure 10, the web of material 26 provided with the strands 29 is oo..

further processed, initially in three planes. To this end, the web of material 26 provided with the strands 29 is simultaneously taken off three intermediary storage I reels 46 arranged one above the other. In the course of take-off, initially the strips 20 are cut into every web of material 26 when each web of material 26 moves past a blade unit 47 to form the (straight-line) incisions between adjacent strips 20. The blade units 47 are liftable from time to time, by lifting means not depicted, disengaging them from the web of material 26 to form

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10 (uncut) holding webs 20 on each occasion.

Downstream of the blade unit 47 for every web of material 26, the apparatus has appropriate blanking means 48, which blank out the incisions 30 between adjacent strips 20. To ensure continuous fabrication, the blanking stations 48 may be of the "flying" type.

Downstream of the blanking stations 48 all three webs of material 26 provided with incisions 27 and 30 are brought together by guiding the two outer layers 22 by deflecting rollers 49 toward the central, inner layer 23, in between a pair of rolls 50. Viewed in the fabrication direction (arrow 51), the pair of rolls 50 is followed by a welding means 52 which serves to join the layers 22 and 23 together in the area of their holding webs 21 to form the weld seam 33. Accordingly, the welding means 52 is S"activated periodically, specifically whenever the three *superposed holding webs 21 of the layers 22 and 23 are in the area of the welding means 52.

The welding means 52 is followed in the fabrication direction by a last pair of rolls 53 and a deflecting roller from where the contact material of connected units is wound onto a stock reel 55. Individual contact material units are removable in succession to assemble S .the trickling filter and are placeable onto appropriate supporting bars 31 of the supporting frame 32.

At least one of the pairs of rolls 50 and 53 of the apparatus is rotatably driveable to pull the web of material 26 to be processed through the blade unit, the blanking unit and the welding means.

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Alternatively, it is conceivable to arrange the 4 apparatus part shown in Figure 10 immediately downstream of the first apparatus section of Figure 9. In this case the winding of the web of material 26 provided with the strands 29 onto the intermediary storage reel 46 is thus omitted. This alternative is suitable in particular for manufacturing contact material from a single-layer web of material 26. But even a multilayered contact material can I be manufactured to completion in successive steps, namely if the individual layers 22 and 23 are produced 11 simultaneously on a plurality of extruders 39.

Finally, Figure 11 shows an alternative to the apparatus shown in Figure 10. This alternative is suitable in particular for manufacturing snakelike strips 36 according to Figures 6 to 8. The waves of the snakelike strips 36 here are formed by a cutting means 56 equipped with a thermocutting pin, a cutting blade, a cutting roll or the like, which during the continuous forward movement of the web of material 26 in the fabrication direction 51 is moved forward and backward transversely thereto at regular intervals. This orthogonal juxtoposition of direction is useful for the simple formation of parallel wavy edges 38 on the strips 36.

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Claims

1. A plastics contact material for biological treatment of water, comprising a plurality of strips made of a plastics material, wherein on each strip at least one tension-absorbing strand is arranged which substantially prevents the associated strip from stretching.

2. The contact material as claimed in claim 1, wherein the tension-absorbing strand or the tension-absorbing strands are connected with the strips in the longitudinal direction thereof for absorbing the load cau.:2d by the biological lawn sticking to the strips.

3. The contact material as claimed in claim 1 or 2, wherein a single strand is arranged approximately in the middle on one side of each strip provided with straight parallel edges.

4. The contact material as claimed in claim 1 or 2, wherein a single elongated strand is attached on one side of each strip having equally wavy parallel edges in such a S• 20 way that the strand extends in a straight line between these wavy edges along the entire length of the strips in order to absorb the tension applied to the strips by a biological lawn located thereon.

The contact material as claimed in claim 3 or 4, wherein the tension-absorbing strand is firmly bonded to the strips by welding or sealing.

6. The contact material as claimed in any one of claims 1 to 5, wherein the strands have a substantially circular cross-section, the diameter of the strands being S 30 substantially greater than the thickness of the strips and the strands consist of a thermoplastic of low extensibility.

7. The contact material as claimed in any one of **claims 1 to 6, wherein the strips are connected to a holding I web.

8. The contact material as claimed in claim 7, wherein the holding web extends transversely to the strips, with groups of strips being arranged spaced apart and side s by side on opposite longitudinal edges of the holding web. 'Ji;_-8533 S JM 8143A/bm 13

9. The contact material as claimed in claim 7 or 8, wherein a plurality of holding webs with strips arranged thereon are gathered together on top of one another and bonded together at the holding webs.

10. A process for manufacturing a biological water treatment contact material made of a plurality of strips of a plastics material, in particular a contact material as claimed in any one of claims 1 to 9, which comprises continuously connecting one or more strands produced with the agency of heat to a web serving for forming the strips while said strands are still in the hot or warm state.

11. The process as claimed in claim 10, wherein the hot strand or the still hot strands are sealed or welded onto the cold web under the action of pressure, in such a way that a plurality of parallel strands are sealed or welded onto the web serving to form a plurality of side by side strips.

12. The process as claimed in claim 10 or 11, 2 wherein, after the strands have been sealed or welded onto 20 the web, the latter is passed with the strands through a o cooling means where the web becomes crimped due to the shrinkage of the cooling strands.

13. The process as claimed in claim 10 or 11, wherein, after the strands have cooled down, the web is continuously divided between pairs of adjacent strands to form side by side strips with strands attached thereto.

14. The process as claimed in claim 13, wherein the cutting of strips out of the web is suspended at regular intervals to form holding webs connecting together the side I°Q 30 by side strips.

The process as claimed in claim 12, wherein, after the strands have cooled down, the web provided therewith is wound onto an intermediary storage reel and corresponding webs are then simultaneously taken off a plurality of such intermediary storage reels, cut and then bonded to the holding web. 53r 3S: -8"533S:JM 1* r A 14

16. A plastics contact material for the treatment of a liquid, according to any one embodiment substantially as hereinbefore described with reference to figures 1 to or 6 to 8 in conjunction with figures 10 and 11 respectively. Dated this 25th day of March 1991 NORDDEUTSCHE SEEKABELWERKE AKTIEGESELLSCHAFT By their Patent Attorneys GRIFFITH HACK CO. 6* 0e 9* 0 0 90 0 0 0 00*000 0 0.0. 0* 00 0 0. *9 00 0 000 00 0 0* 00 A 4 -2' LI 8533 S:JM