DK166093B

DK166093B - Ground reservoir

Info

Publication number: DK166093B
Application number: DK580489A
Authority: DK
Inventors: Leif Holger Winther
Original assignee: Cowiconsult A S
Priority date: 1989-11-17
Filing date: 1989-11-17
Publication date: 1993-03-08
Also published as: DK166093C; DK580489D0; DK580489A

Description

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Opfindelsen vedrører et terrænbassin, hvis bund er beliggende under terræn og er tætnet med en fleksibel folie, hvilket bassin er omkranset af en vold, således at væske-5 niveauet kan hæves et stykke over terrænniveau for at modvirke opadvirkende kræfter på folien fra underlaget.BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a terrain pool whose bottom lies beneath the terrain and is sealed with a flexible foil, which is enclosed by a force so that the liquid level can be raised slightly above ground level to counteract upward forces on the foil from the substrate.

En sådan bassinkonstruktion er væsentlig billigere end tilsvarende betonkonstruktioner, men til gengæld er den 10 fleksible folie mere sårbar navnlig, hvis der skulle forekomme resulterende opadrettede kræfter på folien.Such a pool construction is considerably cheaper than similar concrete structures, but on the other hand, the 10 flexible foil is more vulnerable especially if resulting upward forces are present on the foil.

Dette kan ske som følge af høj grundvandsstand, hvilken modvirkes ved at hæve væskeniveauet i bassinet.This may be due to high groundwater level, which is counteracted by raising the fluid level in the basin.

15 Hidtil har de billige bassiner kun været brugt når væsken i det væsentlige er i hvile, idet kraftige tubulenser fremkalder lokale, dynamiske undertryk, som kan løfte membranen fri af underlaget, således at den med tiden bliver ødelagt og bassinet bliver utæt.So far, the cheap basins have only been used when the liquid is essentially at rest, with strong tubulars eliciting local, dynamic suppressions that can lift the membrane free of the substrate so that over time it becomes damaged and the basin becomes leaky.

2020

Ved rensningsanlæg frembringes der lokalt kraftige turbulenser i rensebassinerne som følge af propeller, som sætter vandet i bevægelse og krumme skillevægge som af-bøjer vandstrømmene. De hydrodynamiske kræfter kan lokalt 25 blive store og give anledning til bevægelser af den fleksible folie, således at den med tiden bliver utæt. Et utæt bassin i et rensningsanlæg kan medføre alvorlig forurening af grundvandet.At purification plants, locally strong turbulences are generated in the purge basins as a result of propellers which move the water and curved partitions that deflect the water currents. The hydrodynamic forces can locally be large and give rise to movements of the flexible foil so that it becomes leaky over time. A leaking basin in a treatment plant can cause serious contamination of the groundwater.

30 I forbindelse med den voksende miljøbevidsthed kræver lovgivningen, at flere og flere industrivirksomheder opretter egne rensningsanlæg, hvilket forstærker behovet for billige og fleksible rensningsanlæg, hvor anlægsudgiften er begrænset og kan afskrives over få år.30 In the context of growing environmental awareness, legislation requires that more and more industrial companies set up their own treatment plants, which reinforces the need for cheap and flexible treatment plants, where construction costs are limited and can be depreciated over a few years.

Formålet med opfindelsen er at tilvejebringe et prisbilligt terrænbassin, som er velegnet i forbindelse med an- 35The object of the invention is to provide an inexpensive terrain pool suitable for use with

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2 vendelsesområder, hvor der kan forekomme kraftige turbulenser, f.eks. ved rensningsanlæg. Dette formål opnås ved den i krav l’s kendetegnende del angivne konstruktion. Opfindelsen kan således siges at bestå i den erkendelse, 5 at man 'blot ved en ekstraordinær hævning af vandstanden kan imødegå de ulemper som er årsagen til, at man hidtil ikke har anvendt de prisbillige terrænbassiner med en fleksibel folie i forbindelse med f.eks. rensningsanlæg, hvor den anvender propeller som omrørere.2 turning areas where severe turbulence may occur, e.g. at wastewater treatment plants. This object is achieved by the construction as defined in claim 1. The invention can thus be said to consist in the recognition that, by an extraordinary raising of the water level, one can counteract the disadvantages which have caused the hitherto inexpensive terrain pools with a flexible foil in connection with, for example, the use of water. purification plant, where it uses propellers as agitators.

10 Væsketransportorganerne kan som anført i krav 2 omfatte propeller, hvor det er velkendt, at der lokalt kan opstå en meget kraftig sugevirkning.The fluid conveying means may, as stated in claim 2, comprise propellers, where it is well known that a very strong suction effect can occur locally.

15 Væsketransportorganerne kan også omfatte en sugeledning som anført i krav 3. I klaringstanke afsættes der en del slam på bassinbunden, hvilket typisk kunne fjernes med et mundstykke på en sugeledning efter støvsuger-princippet.The liquid conveying means may also comprise a suction line as claimed in claim 3. In clearance tanks, some sludge is deposited on the pool floor, which could typically be removed with a nozzle on a suction line according to the vacuum cleaner principle.

Det derved etablerede undertryk kunne under normale om-20 stændigheder løfte den fleksible folie, som imidlertid holdes på plads ved bassinet ifølge opfindelsen.The underpressure thus established could, under normal circumstances, lift the flexible film, which however is held in place by the pool according to the invention.

Endelig kan de væsketransporterende organer også omfatte strømningsstyrende vægge som anført i krav 4, hvor det er 25 velkendt, at der opstår et hydrodynamisk undertryk på den side af en krum skillevæg, hvor vandet skal tilbagelægge den største vejlængde.Finally, the fluid transporting means may also comprise flow-controlling walls as set forth in claim 4, wherein it is well known that a hydrodynamic negative pressure occurs on the side of a curved partition where the water is to travel the greatest path length.

Som nævnt er det et iboende træk for opfindelsen, at ter-30 rænbassinet er billigt. Krav 5 angiver en speciel billig udførelsesform, hvor væsketransportorganerne, f.eks. af den ovennævnte art er båret af tværgående dragere. I tilfælde af meget store bassiner kan dragerne være mellemunderstøttet .As mentioned, it is an inherent feature of the invention that the terrain pool is inexpensive. Claim 5 discloses a particularly inexpensive embodiment wherein the liquid transport means, e.g. of the above kind is carried by transverse carriers. In the case of very large basins, the kites may be medium supported.

Krav 6 angiver en foretrukken udførelsesform for terrænbassinet ifølge opfindelsen, hvor bassinet er indrettet 35Claim 6 indicates a preferred embodiment of the terrain basin according to the invention, wherein the basin is arranged

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3 strømningsstyrende vægge er medvirkende til at frembringe hydrodynamiske undertryk, som imidlertid modvirkes af det hævede væskeniveau.3 flow-controlling walls are instrumental in generating hydrodynamic depressions, which, however, are counteracted by the raised fluid level.

5 Opfindelsen vil blive nærmere forklaret i den følgende beskrivelse, idet der henvises til tegningen, hvor fig. 1 viser et snit (A-A fra fig. 2) gennem en udførelsesform for et terrænbassin ifølge opfindelsen, hvor 10 bassinet tjener som procestank til denitrifikation på et rensningsanlæg, fig. 2 viser den på fig. 1 viste procestank set fra oven, medens 15 fig. 3 viser et snit gennem en anden udførelsesform for terrænbassinet ifølge opfindelsen, hvor bassinet er anvendt som efterklaringstank.The invention will be explained in more detail in the following description, with reference to the drawing, in which fig. 1 is a sectional view (A-A of FIG. 2) of one embodiment of a terrain basin according to the invention, wherein the basin serves as a process tank for denitrification on a treatment plant; 2 shows the one shown in FIG. 1 from above, while FIG. 3 shows a section through another embodiment of the terrain basin according to the invention, in which the basin is used as a clarification tank.

20 Fig. 1 viser et terrænbassin, hvor der i en fortrinsvis plan jordoverflade 2 er gravet et hul, som omkranses af f.eks. jord- eller grusvolde 4. Bassinets bund er dækket med et drænbart kapillarbrydende lag 6 på hvilket der er anbragt et lag af foliemateriale 8, der fortrinsvis er en 25 plastmembran. Når bassinet er fyldt op med vand 10, vil foliematerialet 8 blive trykket ned mod drænlaget 6, på grund af det hydrostatiske tryk fra vandet 10. I forbindelse med driftsforstyrrelser eller oprensning af bassinet kan det være ønskeligt at tømme dette for vand.FIG. 1 shows a terrain basin in which, in a preferably flat ground surface 2, a hole is dug, which is encircled by e.g. soil or gravel walls 4. The bottom of the basin is covered with a drainable capillary breaking layer 6 on which is applied a layer of film material 8, which is preferably a plastic membrane. When the basin is filled with water 10, the foil material 8 will be depressed against the drainage layer 6, due to the hydrostatic pressure of the water 10. In connection with operational disturbances or the cleaning of the basin it may be desirable to drain this from water.

30 Hvis der i omgivelserne er et højt grundvandsniveau vil det indre hydrostatiske tryk på bunden af bassinet være utilstrækkeligt under tømningen af dette, hvorfor man i forbindelse med terrænbassinet skal kunne dræne grundvandet væk fra drænlaget 6 gennem drænrør 12 til en 35 pumpebrønd 14.30 If there is a high groundwater level in the surroundings, the internal hydrostatic pressure on the bottom of the basin will be insufficient during emptying thereof, so that in connection with the terrain basin it must be possible to drain the groundwater away from the drainage layer 6 through drainage pipe 12 to a 35 pump well 14.

44

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Bassinet på fig. 1 er indrettet til rensning af spildevand og svarer til et snit langs linien A-A fra fig. 2. Processen i et rensningsanlæg vil kort blive blive beskrevet nedenfor, således at behovet for de i patentkra-5 vene nævnte væsketransportorganer bedre kan forstås.The basin of FIG. 1 is adapted to purify wastewater and corresponds to a section along line A-A of FIG. 2. The process of a purification plant will be briefly described below so that the need for the liquid transport means mentioned in the claims can be better understood.

Ved den på fig. 2 viste udførelsesform er procestanken udformet som en oval, i hvilken der løber to vandstrømme, jvf. pilene. Spildevandet ledes til den ydre vand-10 strøm (se indløb på fig. 2), medens udløbet findes i den indre vandstrøm (se fig. 2). Vandet sættes i cirkulation i tanken, idet den ydre vandstrøm drives ved hjælp af propeller 23, medens den indre vandstrøm drives ved hjælp af propeller 24. Den ydre vandstrøm er ikke beluftet, så-15 ledes at der hersker iltfattige (anoxiske) forhold. I den ydre vandstrøm omdannes nitrat til atmosfærisk kvælstof som bobler op i atmosfæren, medens der i den indre vandstrøm foregår en iltning af ammoniak til nitrat, NOg, hvilket kræver et overskud af ilt. De iltrige (oxiske) 20 forhold skabes ved at vandet tilføres luft via diffusorer 26. Slammet holdes opslemmet i spildevandet ved omrøringen og de deraf følgende vandbevægelser. Den dannede nitrat ledes til den ydre vandstrøm, hvor nitraten omdannes til atmosfærisk kvælstof, ved at nitratens ilt går i for-25 bindelse med det organiske stof til nedbrydelse af dette.In the embodiment of FIG. 2, the process tank is designed as an oval in which two streams of water flow, cf. the arrows. The wastewater is directed to the external water stream (see inlet of Fig. 2), while the outlet is in the internal water stream (see Fig. 2). The water is circulated in the tank, with the external water flow driven by propeller 23, while the internal water flow is driven by propeller 24. The external water flow is not aerated, so that oxygen-poor (anoxic) conditions prevail. In the outer stream of water, nitrate is converted into atmospheric nitrogen which bubbles up in the atmosphere, while in the internal stream of water an oxygenation of ammonia is made into nitrate, NO, which requires an excess of oxygen. The oxygen-rich (oxic) conditions are created by the water being supplied to air via diffusers 26. The sludge is kept slurried in the effluent by stirring and the resulting water movements. The nitrate formed is fed to the external stream of water, where the nitrate is converted into atmospheric nitrogen by the nitrate of oxygen being in contact with the organic matter to decompose it.

For at den ovennævnte proces kan foregå tilfredsstillende, er det nødvendigt, at recirkulationsforholdet mellem den ydre og indre vandstrøm er stort, og det vil kunne 30 forstås, at der lokalt i bassinet kan forekomme store dynamiske trykforskelle for at holde de to vandstrømninger i indbyrdes bevægelse.In order for the aforementioned process to proceed satisfactorily, it is necessary that the recirculation ratio between the outer and the inner water flow is large, and it can be understood that large dynamic pressure differences can occur locally in the basin to keep the two water flows in motion. .

På fig. 1 kan det ses, at motorer for propellerne 23 og 35 24 er monteret under en stålbro 22, som strækker sig hen over bassinet, og ligger af på voldene 4. Ved den viste udførelsesform er stålbroen 22 mellemunderstøttet af et 5In FIG. 1 it can be seen that motors for the propellers 23 and 35 24 are mounted under a steel bridge 22 which extends across the basin and abuts on the ramp 4. In the illustrated embodiment, the steel bridge 22 is supported by a 5

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fundament 21, hvilket kun er nødvendigt ved store bassiner. Når propellerne roterer vil der lokalt blive frembragt et lavt hydrostatisk tryk, der kan blive så lavt, at plastmembranen lokalt påvirkes af en indadrettet re-5 suiterende kraft. Ifølge opfindelsen afpasses det fra propellerne hidrørende sug i forhold til en ekstraordinær stor vandhøjde i bassinet, således at plastmembranen 8 ikke påvirkes af en indadrettet kraft.foundation 21, which is only necessary for large basins. As the propellers rotate, a low hydrostatic pressure will be generated locally, which may become so low that the plastic membrane is locally affected by an inwardly reducing force. According to the invention, suction emitted from the propellers is adapted to an exceptionally high water height in the basin so that the plastic membrane 8 is not affected by an inward force.

10 På fig. 2 kan det ses at der findes tre stålbroer 22, hvor de to udvendige broer bærer både propelmotorer og diffusorer, medens den midterste kun bærer et par diffu-sorer. Under henvisning til fig. 2 vil det kunne forstås, at den ydre vandstrøm gennemløber en større vejlængde end 15 det er tilfældet for den indre vandstrøm, således at der hersker et lavere hydrostatisk tryk i den ydre vandstrøms rundinger, og der vil derfor lokalt kunne frembringes så lave hydrostatiske tryk, at membranen kan løfte sig fra underlaget. Det har imidlertid vist sig, at en ekstra-20 ordinær stor vandstand ifølge opfindelsen kan hindre denne uheldige påvirkning af membranen.10 In FIG. 2 it can be seen that there are three steel bridges 22, the two outer bridges carrying both propeller motors and diffusers, while the middle one carries only a few diffusers. Referring to FIG. 2, it will be appreciated that the outer water flow extends a greater path length than 15 in the case of the inner water flow, so that a lower hydrostatic pressure prevails in the outer water flow rounds, and thus locally low hydrostatic pressure can be generated, that the membrane can lift from the substrate. However, it has been found that an extraordinarily large water level according to the invention can prevent this adverse effect on the membrane.

Ved den viste udførelsesform er væggene 20 anbragt på respektive fundamenter 19, da kraftpåvirkningerne er meget 25 store ved store vandmængder. En fordel ved opfindelsen er imidlertid, at der kan opnås mindre og meget prisbillige bassiner til lokale rensningsanlæg, og i tilfælde af mindre bassiner kan væggene 20 være ophængt på stålbroerne 22. Dette medfører yderligere den fordel, at væggene 30 20 kan være anbragt bevægelige på den respektive bro, så ledes at væggene kan sideforskydes indbyrdes (fig. 2), hvorved recirkulationsforholdet i bassinet kan reguleres.In the embodiment shown, the walls 20 are arranged on respective foundations 19, since the force effects are very large at high volumes of water. However, an advantage of the invention is that smaller and very affordable basins can be obtained for local wastewater treatment plants, and in the case of smaller basins, the walls 20 may be suspended on the steel bridges 22. This further has the advantage that the walls 30 20 can be arranged movable on the respective bridge so that the walls can be laterally displaced (Fig. 2), whereby the recirculation ratio in the basin can be regulated.

På fig. 3 er der vist en udførelsesform for opfindelsen, 35 hvor bassinet er anvendt som klaringstank. Der er vist to rektangulære, indbyrdes parallelle bassiner 30 og 31, hvor der på tværs af bassinerne findes en bro hhv. 32 ogIn FIG. 3, an embodiment of the invention is shown in which the basin is used as a clearance tank. Two rectangular, mutually parallel basins 30 and 31 are shown, with a bridge and a cross-section respectively. 32 and

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6 33, som er bevægelig i bassinets længderetning ved at broernes ender er understøttet af køreskinner 34, 35, 36, 37. På hver bro findes der en pumpe 38, 39 hvis sugeside er forbundet med et antal slamsugere via sugeledninger.6 33, which is movable in the longitudinal direction of the basin in that the ends of the bridges are supported by running rails 34, 35, 36, 37. On each bridge there is a pump 38, 39 whose suction side is connected to a number of sludge suction lines via suction lines.

5 Slamsugerne er i bassinet 30 angivet ved 40-43. I klaringsbassinerne afsættes slammet på bunden og for at fjerne slammet suges en blanding af vand og slam op ved hjælp af pumperne, hvorved der lokalt tilvejebringes relativt lavt tryk omkring slamsugernes munding. Ved ifølge 10 opfindelsen at etablere en tilstrækkelig høj væskestand i bassinet, kan der tolereres et tilstrækkeligt sug i forbindelse med slamsugningen uden at folien 8 påvirkes i retning bort fra det understøttende jordlag.The sludge suction units are indicated in the basin 30 at 40-43. In the clearing basins, the sludge is deposited on the bottom and to remove the sludge a mixture of water and sludge is sucked up by means of the pumps, thereby providing relatively low pressure around the mouth of the sludge suction. By establishing a sufficiently high liquid level in the basin according to the invention, a sufficient suction can be tolerated in connection with the sludge suction without affecting the foil 8 in the direction away from the supporting soil layer.

15 Sammenfattende er det ovenfor beskrevet, hvorledes en ekstraordinær forøgelse af vandstanden i bassinet tillader, at der anvendes plastfolie som bassinvæg på trods af, at der etableres kraftige vandstrømninger i bassinet.In summary, it is described above how an extraordinary increase in water level in the basin allows the use of plastic foil as a basin wall despite the establishment of strong water flows in the basin.

20 25 30 3520 25 30 35

Claims

7 DK 166093 B Patent claims:

A terrain pool, the bottom of which is located beneath the terrain and 5 is sealed with a flexible foil, which is surrounded by a force so that the liquid level can be raised slightly above the terrain level to counteract upward forces on the foil from the substrate, characterized in that immersed in the basin are fluid transport means which locally produce a dynamic negative pressure and that the fluid level is raised further to counteract said negative pressure.

Basin according to claim 1, characterized in that the liquid transport means comprise propellers for generating fluid circulation in the basin.

Pool according to claim 1 or 2, characterized in that the liquid transport means comprise a suction line 20 which opens in the vicinity of the pool bottom.

Basin according to claims 1-3, wherein the fluid is moving in the basin, characterized in that the fluid transport means comprise flow-controlling walls. 25

Basin according to claims 1-4, characterized in that there are transverse carriers resting on the basins above the basin and that the liquid transport means are mounted on and suspended from the dragons. 30

Basin according to claims 1-5, characterized in that there are propellers (24) for recirculating the water and that there are flow-controlling walls arranged to divide the water into two partially separated water streams, and that there are diffusers for aerating at least one stream of water.