WO2002090269A1 - Biological treatment reactor in a purification plant - Google Patents

Biological treatment reactor in a purification plant Download PDF

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Publication number
WO2002090269A1
WO2002090269A1 PCT/FR2002/001565 FR0201565W WO02090269A1 WO 2002090269 A1 WO2002090269 A1 WO 2002090269A1 FR 0201565 W FR0201565 W FR 0201565W WO 02090269 A1 WO02090269 A1 WO 02090269A1
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WO
WIPO (PCT)
Prior art keywords
effluent
treatment
basin
treatment plant
plant according
Prior art date
Application number
PCT/FR2002/001565
Other languages
French (fr)
Inventor
Raymond Bragoni
Original Assignee
Ingenium Sarl
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from FR0106123A external-priority patent/FR2824548B1/en
Priority claimed from FR0106125A external-priority patent/FR2824550B1/en
Application filed by Ingenium Sarl filed Critical Ingenium Sarl
Priority to EP02732855A priority Critical patent/EP1390304A1/en
Publication of WO2002090269A1 publication Critical patent/WO2002090269A1/en

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00—Biological treatment of water, waste water, or sewage
    • C02F3/02—Aerobic processes
    • C02F3/08—Aerobic processes using moving contact bodies
    • C02F3/082—Rotating biological contactors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D17/00—Separation of liquids, not provided for elsewhere, e.g. by thermal diffusion
    • B01D17/02—Separation of non-miscible liquids
    • B01D17/0202—Separation of non-miscible liquids by ab- or adsorption
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D17/00—Separation of liquids, not provided for elsewhere, e.g. by thermal diffusion
    • B01D17/02—Separation of non-miscible liquids
    • B01D17/0208—Separation of non-miscible liquids by sedimentation
    • B01D17/0214—Separation of non-miscible liquids by sedimentation with removal of one of the phases
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D21/00—Separation of suspended solid particles from liquids by sedimentation
    • B01D21/02—Settling tanks with single outlets for the separated liquid
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2209/00—Controlling or monitoring parameters in water treatment
    • C02F2209/42—Liquid level
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W10/00—Technologies for wastewater treatment
    • Y02W10/10—Biological treatment of water, waste water, or sewage

Definitions

  • the present invention relates to domestic wastewater treatment plants and relates in particular to a treatment plant comprising a biological treatment reactor whose purpose is to purify this water before it is discharged into the environment.
  • Wastewater treatment plants generally include a pre-treatment unit located upstream of the treatment reactor where the first stage of the actual treatment of the effluent takes place using a physicochemical process using chemicals which have unfortunately a bad impact on the environment or a biological process using living organisms such as bacteria, and whose release in nature is made possible without risk of pollution on the environment.
  • a pre-treatment unit located upstream of the treatment reactor where the first stage of the actual treatment of the effluent takes place using a physicochemical process using chemicals which have unfortunately a bad impact on the environment or a biological process using living organisms such as bacteria, and whose release in nature is made possible without risk of pollution on the environment.
  • the effluent from the pre-treatment set is prepared to receive a biological treatment after which it is rejected in nature.
  • the first stage of treatment is essential, it consists in bringing the effluent into contact with microorganisms for a certain time so that they feed on the organic matter contained in the effluent.
  • This step can be carried out in a basin by microorganisms in free cultures, that is to say mixed with the effluent or by microorganisms in cultures fixed on supports placed at the bottom of the basin, in plastic or in pozzolan.
  • Microorganisms need oxygen to live and the effluent from the basin must be regularly oxygenated and stirred which requires either additional equipment compressor or aerator type or any other system allowing mixing, either a cascade or trickling process.
  • the water from this first tank can then pass into a tank called a clarifier which allows, by decantation, to separate the "clean" water from the residual sludge containing the dead micro-organisms and the products not digested by them.
  • the clarified and clean water is discharged into the environment while the sludge is sent to another basin called a silo before being reintroduced into the natural environment.
  • the technique of fixed cultures is advantageously improved thanks to supports in the form of cylindrical elements as described in the document EP0936189, fixed on a horizontal axis of rotation and half submerged. These cylindrical elements are crossed by parallel channels which extend in the transverse direction of the element and whose internal surface serves as a support for fixing the microorganisms so that these are alternately bathed by the effluent and aerated by ambient air.
  • This mode of fixed cultures has the advantage of increasing the concentration of bacterial biomass in the basins and therefore of reducing their size.
  • the fixed cultivation technique requires practically no monitoring and makes it possible to reduce the oxygenation of the effluent and therefore to reduce the energy cost.
  • this channel system inside the cylindrical elements does not allow an adequate development of microorganisms. Indeed, if the cylindrical elements rotate at too high a speed, the tubes containing the cultures of microorganisms are "washed” by the passage of the effluent during the rotation thus preventing any bacteriological development. On the other hand, if the elements rotate at too low a speed, for example 1 to 2 revolutions per minute, so as to avoid the "washing" of the channels, they generate very few movements of the effluent and therefore very low oxygenation. Now, the low oxygenation of such a medium causes the formation of nitrates and the accumulation of phosphates, which implies additional stages of denitrification and dephosphatation since these high-dose products are very toxic.
  • the object of the invention is therefore to provide a wastewater treatment plant comprising a biological effluent treatment reactor which allows a significant development of cultures of microorganisms at the same time as a suitable oxygenation of 1 ' effluent.
  • the object of the invention is a wastewater treatment plant comprising a biological treatment reactor responsible for treating the effluent comprising cylindrical elements fixed on an axis of rotation intended for the cultivation of micro- aerobic and anaerobic organisms for the degradation of organic matter contained in the effluent, the cylindrical elements being partly immersed in the effluent and having recesses, channels, or cells so as to allow the oxygenation of the effluent, the oxygenation of microorganisms and contact of microorganisms with organic matter in the effluent.
  • the cylindrical elements are thin disks formed of two substantially parallel plates separated by a cellular material with open cells, the external faces of the plates serving to support the culture of said aerobic and anaerobic microorganisms.
  • FIG. 1 is a block diagram of a treatment plant incorporating a biological treatment reactor according to the invention
  • FIG. 2 is a sectional view of a pretreatment tank which can be used in combination with the biological treatment reactor according to the invention
  • FIG. 3 represents a cross section of the pre-treatment tank, represented in FIG. 3, along the axis A- A of FIG. 2,
  • Figure 4 is a schematic representation of the biological treatment reactor according to the invention.
  • a wastewater treatment plant in accordance with the invention shown diagrammatically in FIG. 1, includes a pre-treatment unit 10 allowing the dissolution or degradation into fine particles of the solid materials contained in the effluent arriving from the collector 11, a biological reactor 12 in which the effluent is treated and a clarifier 14 intended to separate by sedimentation the sludges from the reactor from the treated water.
  • the station also includes a sludge silo 16, the outlet of which consists of a liquid part recycled at the inlet of the pre-treatment tank and a part containing the sludge to be removed.
  • the effluent is conveyed from the pre-treatment unit to the reactor by a line 13 and from the reactor to the clarifier by a line 15. From the clarifier 14, the purified water is discharged into nature through the outlet 17, and from the silo to sludge 16, the thickened sludge is removed through outlet 19.
  • the pretreatment assembly is a tank 10 preferably masonry, flat bottom and whose dimensions vary according to the amount of domestic wastewater to manage. It is separated into two basins 22 and 24, by a partition centered vertically.
  • the partition is composed, from bottom to top, of a first fixed and waterproof partition 26, of a permeable and movable wall 28 and of a second fixed and waterproof partition 30.
  • the three parts that make up the partition central each represent about a third of the total height of the partition.
  • the effluent containing the domestic wastewater arrives in the basin 22 through a collector 11.
  • the materials contained in the effluent have different densities and consequently the materials of high density such as sands and heavy materials tend to deposit in the lower part of the basin while low density materials such as grease and moss go up in the upper part of the basin.
  • the major part of the effluent is therefore in the central part of the basin 22 and migrates towards the basin 24 via the permeable wall 28.
  • the effluent being in the basin 22 is evacuated towards the biological reactor by means of a hydraulic pump 32 and conduits 34 and 13. This pumping therefore naturally creates a flow of effluent from the basin 22 to the basin 24 through the permeable wall 28.
  • the regulation of the flow consists in returning towards the basin 22 a portion of the effluent of the basin 24 by means of the hydraulic pump 32 and the conduits 34 and 40 while another portion of the effluent pumped by means of the hydraulic pump 32 (or of another pump) is sent into the reactor via the pipe 13.
  • This recycling therefore constitutes a reflux of the effluent from the basin 24 to the basin 22 which attenuates the flows from basin 22 to basin 24 through the permeable wall 28 and which contributes to the homogenization of the effluent.
  • an electromechanically adjusted valve 38 makes it possible to stop the return of the effluent from the basin 24 to the basin 22 and therefore to regulate the flow during a sharp increase in the flow of incoming effluent.
  • this valve is adjusted to allow a period of time between reflux in the first tank 22 and the suction to the treatment reactor thus allowing the non-degraded materials to find their place in the tank 22.
  • the flow control system proper comprises a programmable electronic control system 44 connected to at least one level sensor 42 of the mercury sensor type for example, to the hydraulic pump (s) 32 and to the solenoid valve 38.
  • Safety level contacts can also be connected to the control system in order to prevent any malfunction of the device, breakdown of a pump for example.
  • the electronic control system 44 can act by an automaton, therefore without human intervention, according to a certain number of instructions such as the time of the day, the season, the quantities of effluent entering and / or transferred to the following stages of treatment ...
  • the regulation system is programmed to receive the parameters inherent to the treatment plant to be controlled by means of printed cards previously established according to the needs of the municipality.
  • a characteristic of the pre-treatment system according to the invention is to treat the effluent as much as possible to make it as homogeneous as possible. This is what allows the pipe 50 for returning the effluent (coming from the pipe 40) illustrated in FIG. 3, the outlet of which is located in the lower part of the basin 22. This creates a vortex which stirs the heavy parts or high density solids located in zone 54 and reduces them to fine particles so that they dissolve or are easily entrained in the liquid effluent by crossing the wall 28. Note that a second conduit reference 52
  • the effluent resulting from the pre-treatment tank (also called liquor) is sent via the hydraulic pump, to the treatment reactor 14.
  • the treatment reactor is a basin in which a certain number of discs 60-1 to 60-3 half immersed in the effluent 64 to be treated rotate slowly around an axis 62 at a speed of the order of 1 to 2 revolutions per minute.
  • the discs about 2m in diameter and whose thickness does not exceed 1 cm (preferably 5 mm) are preferably formed from two circular plates 70 and 72 substantially parallel and separated by a cellular material 74 with open cells allowing the 'effluent to be stirred and thus to be oxygenated and homogenized. In fact, the ambient air trapped in the disc cells enters the effluent in large quantities.
  • the effluent becomes saturated with oxygen, the diffusion of oxygen then begins towards the deeper layers of the effluent.
  • a quantity of effluent itself circulates in the cells or alveoli of the discs and is all the more stirred and oxygenated.
  • the discs can have a shape other than circular without departing from the scope of the invention.
  • the discs are made of polypropylene. This material has, among other things, the following two advantages: its low density which reduces its weight and its low thermal conductivity which contributes to the non-dispersion of heat.
  • the hollow structure of the discs also considerably lightens the support.
  • the effluent arrives on one side of the reactor via the conduit 13 and leaves the opposite side of the reactor via the outlet 15 by gravity, the outlet 15 being situated substantially at the level of the axis 62 of the discs in order to keep the level d constant. 'effluent in the reactor.
  • the inlet and the outlet of the effluent create a flow of the effluent from one end to the other of the reactor.
  • the two faces of the discs serve as a support for microorganisms, in particular aerobic and anaerobic bacteria which will then feed on the pollutant load of effluent 64.
  • This technique of "fixed culture” uses the capacity that most have microorganisms to produce exo-polymers allowing their fixation on very diverse supports to form a biofilm.
  • the colonization of a disc begins on a certain number of privileged sites, these sites gradually extending until forming a bio-film which develops continuously until covering of the total surface of the two faces of the disc by a layer single cell. From this moment, the growth is continuous by production of new layers which come to cover the initial layer. A number of culture layers are therefore stratified in such a way that the oxygen which diffuses through the thickness of the biofilm does not reach the deepest layer. The colonization of the discs does not take place inside the cells or alveoli since they are washed by the passage of the effluent during the rotation of the discs, thus preventing any bacteriological development.
  • the faces of the disc are therefore covered with a layer of anaerobic bacteria and a layer of aerobic bacteria.
  • an aerobic environment part of the organic matter contained in the effluent to be treated is consumed thanks to the oxygen dissolved in the effluent by aerobic bacteria and degraded into biomass and carbon dioxide.
  • anaerobic environment another part of the matter organic matter contained in the effluent is consumed away from oxygen by anaerobic bacteria and degraded in biomass, methane and carbon dioxide.
  • the microorganisms that make up the layer of aerobic bacteria consume oxygen for their energy needs, their reproduction by cell division called bacterial synthesis and their endogenous respiration.
  • the homogenization of the effluent ensured by the rotation of the discs ensures intimate contact between polluting elements and bacteria.
  • the oxygen supply also ensured by the rotation of the discs avoids additional equipment of the compressor or aerator type or any other system allowing mixing, or a cascade or trickling process.
  • the low oxygenation of the effluent would cause the formation of nitrates and the accumulation of phosphates, which would imply additional stages of denitrification and of phosphating since these products in high doses are very toxic.
  • the load variations of organic matter to be degraded are smoothed by the principle of homogenization and the regulation system of the pre-treatment tank.
  • the biological film in activity on the discs has the property of absorbing a load ten times greater than the normal load, without altering the quality of the outlet water.
  • the so-called "normal" load is evaluated by a preliminary dimensioning carried out from a certain number of parameters for the implantation of each treatment plant.
  • the biological mass present on the discs is also able to absorb and digest the complex molecules that constitute hydrocarbons, fats and other fats not absorbed by the pretreatment. These molecules arriving in the reactor are condemned to deposit on the discs during their rotation, which allows the bacteria in activity on the discs to feed in optimal proportion of this pollution.
  • the biological reactor treatment system according to the invention is capable of absorbing up to 100 mg of fat per liter of effluent while the proportions estimated in domestic discharges never exceed 40 to 60 mg per liter.
  • the depolluted effluent is loaded with sludge consisting of dead bacteria and inert materials. It is transferred by means of the outlet 15 into a basin or clarifier 14 where it is subjected to a natural decantation allowing the separation of the sludge and the purified water.
  • the settling allows the clarification of the effluent and the thickening of the mud.
  • Biological sludge is generally fluffy and has a density very close to that of water, and therefore, the duration of decantation is a parameter to take into account in the design of the treatment plant.
  • the capacity of the effluent to settle depends on a certain number of factors such as: the presence of industrial waste, the dissolved oxygen content, the variation in composition of the organic load of the effluent, the temperature, etc.
  • the measurement of the ascent rate is a common parameter in clarification tanks.
  • the guide values for domestic effluents vary on average over a day depending on whether the organic load is low or high between 0.3 m / h and 1.25 m / h.
  • the treatment system according to the invention makes it possible to accept all of the effluent arriving at the station, to smooth the variations in charge of organic matter by the principle of homogenization and the system for regulating the pre-treatment tank.
  • the upward speed of the sludge in the clarifier is greatly increased compared to traditional treatment plants and reaches 2 to 2.5 m / h.
  • This significant upward speed of the mud makes it possible to reduce the volume of the clarifier and in particular to decrease its surface area, which represents a non-negligible impact on the investment cost, both in terms of civil engineering and that of the right-of-way. land.
  • the purified water is discharged into the environment while the sludge is placed in a closed sludge silo 16 while awaiting their evacuation and / or their liquefaction.
  • the sludge can have several final destinations such as agricultural recovery, incineration or landfill. Their elimination from traditional treatment plants represents, every three months approximately, a significant transport cost.
  • the sludge from the treatment plant according to the invention undergoes liquefaction due to the very composition of the sludge. Indeed, the combination of the pretreatment system and the reactor as described here produces sludges whose composition is not comparable to the sludges produced in traditional treatment plants.
  • the sludge from the treatment plant according to the invention contains compounds in small quantities such as nitrates, phosphates, materials inorganic and organic which together continue to undergo anaerobic degradation.
  • the frequency of withdrawal of the sludge from silo 16 is reduced compared to a traditional process.
  • the biological treatment reactor according to the invention is preferably used with a two-tank pretreatment system as described above, it is also possible that this same reactor is used following a pre-treatment. conventional treatment without departing from the scope of the invention.

Abstract

The invention concerns a waste water purification plant comprising a biological treatment reactor for treating effluent including cylindrical elements fixed on a rotary shaft (62) designed for aerobic and anaerobic micro-organism culture for degradation of organic matters contained in the effluent, said cylindrical elements being partly immersed in the effluent and having recesses, channels, or cells so as to enable oxygenation of the effluent, oxygenation of the micro-organisms and contact between the micro-organisms and the organic matters of the effluent. The invention is mainly characterised in that the cylindrical elements are thin discs (60-1 to 60-3) consisting of two substantially parallel plates (70 and 72) separated by a cellular material (74) with open cells, the outer sides of the plates serving as support to the aerobic and anaerobic micro-organism culture.

Description

Réacteur de traitement biologique dans une station d'épuration Biological treatment reactor in a treatment plant
Domaine techniqueTechnical area
La présente invention concerne les stations d'épuration des eaux usées domestiques et concerne en particulier une station d'épuration comprenant un réacteur de traitement biologique ayant pour but d'épurer ces eaux avant leur rejet dans la nature.The present invention relates to domestic wastewater treatment plants and relates in particular to a treatment plant comprising a biological treatment reactor whose purpose is to purify this water before it is discharged into the environment.
Etat de la techniqueState of the art
Les stations d'épuration des eaux usées comprennent généralement un ensemble de pré-traitement situé en amont du réacteur de traitement où a lieu la première étape du traitement proprement dit de l'effluent grâce à un procédé physico-chimique utilisant des produits chimiques qui ont malheureusement un mauvais impact sur l'environnement ou à un procédé biologique utilisant des organismes vivants tels que des bactéries, et dont le rejet dans la nature est rendu possible sans risque de pollution sur l'environnement. Nous ne parlerons ici que des traitements faisant appel aux méthodes dites biologiques, dont l'objet de l'invention fait partie.Wastewater treatment plants generally include a pre-treatment unit located upstream of the treatment reactor where the first stage of the actual treatment of the effluent takes place using a physicochemical process using chemicals which have unfortunately a bad impact on the environment or a biological process using living organisms such as bacteria, and whose release in nature is made possible without risk of pollution on the environment. We will only speak here of treatments using so-called biological methods, of which the subject of the invention is part.
L'effluent issu de l'ensemble de pré-traitement est préparé pour recevoir un traitement biologique à l'issue duquel il est rejeté dans la nature. La première étape du traitement est essentielle, elle consiste à mettre en contact l'effluent avec des micro-organismes un certain temps afin que ceux-ci se nourrissent des matières organiques contenues dans l'effluent. Cette étape peut être réalisée dans un bassin par des micro-organismes en cultures libres c'est à dire mélangés à l'effluent ou par des micro-organismes en cultures fixées sur des supports posés au fond du bassin, en plastique ou en pouzzolane. Les micro-organismes ont besoin d'oxygène pour vivre et l'effluent du bassin doit être régulièrement oxygéné et brassé ce qui nécessite soit un équipement supplémentaire de type compresseur ou aérateur ou de tout autre système permettant le brassage soit un procédé de cascade ou de ruissellement .The effluent from the pre-treatment set is prepared to receive a biological treatment after which it is rejected in nature. The first stage of treatment is essential, it consists in bringing the effluent into contact with microorganisms for a certain time so that they feed on the organic matter contained in the effluent. This step can be carried out in a basin by microorganisms in free cultures, that is to say mixed with the effluent or by microorganisms in cultures fixed on supports placed at the bottom of the basin, in plastic or in pozzolan. Microorganisms need oxygen to live and the effluent from the basin must be regularly oxygenated and stirred which requires either additional equipment compressor or aerator type or any other system allowing mixing, either a cascade or trickling process.
Les eaux issues de ce premier bassin peuvent ensuite passer dans un bassin appelé clarificateur qui permet par décantation de séparer l'eau "propre" des boues résiduelles contenant les micro-organismes morts et les produits non digérés par ceux-ci. L'eau clarifiée et propre est rejetée dans la nature tandis que les boues sont dirigées vers un autre bassin appelé silo à boues avant leur réintroduction dans le milieu naturel.The water from this first tank can then pass into a tank called a clarifier which allows, by decantation, to separate the "clean" water from the residual sludge containing the dead micro-organisms and the products not digested by them. The clarified and clean water is discharged into the environment while the sludge is sent to another basin called a silo before being reintroduced into the natural environment.
La technique de cultures fixées est avantageusement améliorée grâce à des supports en forme d'éléments cylindriques tels que décrits dans le document EP0936189, fixés sur un axe de rotation horizontal et à demi immergés. Ces éléments cylindriques sont traversés par des canaux parallèles qui s'étendent dans le sens transversal de l'élément et dont la surface interne sert de support de fixation des micro-organismes de sorte que ceux-ci sont alternativement baignés par l'effluent et aérés par l'air ambiant. Ce mode de cultures fixées a l'avantage d'augmenter la concentration en biomasse bactérienne dans les bassins et donc de réduire leur taille. De plus, la technique de cultures fixées demande une surveillance pratiquement nulle et permet de réduire l'oxygénation de l'effluent et donc de réduire le coût énergétique.The technique of fixed cultures is advantageously improved thanks to supports in the form of cylindrical elements as described in the document EP0936189, fixed on a horizontal axis of rotation and half submerged. These cylindrical elements are crossed by parallel channels which extend in the transverse direction of the element and whose internal surface serves as a support for fixing the microorganisms so that these are alternately bathed by the effluent and aerated by ambient air. This mode of fixed cultures has the advantage of increasing the concentration of bacterial biomass in the basins and therefore of reducing their size. In addition, the fixed cultivation technique requires practically no monitoring and makes it possible to reduce the oxygenation of the effluent and therefore to reduce the energy cost.
Cependant, ce système de canaux à l'intérieur des éléments cylindriques ne permet pas un développement adéquat des micro-organismes. En effet, si les éléments cylindriques tournent à une vitesse trop élevée, les tubes contenant les cultures de micro-organismes sont "lavés" par le passage de l'effluent au cours de la rotation empêchant ainsi tout développement bactériologique. Par contre, si les éléments tournent à une vitesse trop faible, par exemple 1 à 2 tours par minute, de façon à éviter le "lavage" des canaux, ils engendrent très peu de mouvements de l'effluent et donc une très faible oxygénation. Or, la faible oxygénation d'un tel milieu engendre la formation des nitrates et l'accumulation des phosphates, ce qui implique des étapes supplémentaires de dénitrification et de dephosphatation étant donné que ces produits à haute dose sont très toxiques .However, this channel system inside the cylindrical elements does not allow an adequate development of microorganisms. Indeed, if the cylindrical elements rotate at too high a speed, the tubes containing the cultures of microorganisms are "washed" by the passage of the effluent during the rotation thus preventing any bacteriological development. On the other hand, if the elements rotate at too low a speed, for example 1 to 2 revolutions per minute, so as to avoid the "washing" of the channels, they generate very few movements of the effluent and therefore very low oxygenation. Now, the low oxygenation of such a medium causes the formation of nitrates and the accumulation of phosphates, which implies additional stages of denitrification and dephosphatation since these high-dose products are very toxic.
Exposé de l'inventionStatement of the invention
Le but de l'invention est donc de fournir une station d'épuration des eaux usées comprenant un réacteur de traitement biologique de l'effluent qui permet un développement important des cultures de micro-organismes en même temps qu'une oxygénation convenable de 1' effluent .C est pourquoi l'objet de l'invention est une station d'épuration des eaux usées comprenant un réacteur de traitement biologique chargé de traiter l'effluent comportant des éléments cylindriques fixés sur un axe de rotation destinés à la culture de micro-organismes aérobies et anaérobies pour la dégradation des matières organiques contenues dans l'effluent, les éléments cylindriques étant en partie immergés dans l'effluent et ayant des evidements, canaux, ou alvéoles de manière à permettre l'oxygénation de l'effluent, l'oxygénation des micro-organismes et le contact des micro-organismes avec les matières organiques de l'effluent. Selon une caractéristique principale de l'invention, les éléments cylindriques sont des disques minces formés de deux plaques sensiblement parallèles séparées par un matériau cellulaire à cellules ouvertes, les faces externes des plaques servant de support à la culture desdits micro-organismes aérobies et anaérobies.The object of the invention is therefore to provide a wastewater treatment plant comprising a biological effluent treatment reactor which allows a significant development of cultures of microorganisms at the same time as a suitable oxygenation of 1 ' effluent. This is why the object of the invention is a wastewater treatment plant comprising a biological treatment reactor responsible for treating the effluent comprising cylindrical elements fixed on an axis of rotation intended for the cultivation of micro- aerobic and anaerobic organisms for the degradation of organic matter contained in the effluent, the cylindrical elements being partly immersed in the effluent and having recesses, channels, or cells so as to allow the oxygenation of the effluent, the oxygenation of microorganisms and contact of microorganisms with organic matter in the effluent. According to a main characteristic of the invention, the cylindrical elements are thin disks formed of two substantially parallel plates separated by a cellular material with open cells, the external faces of the plates serving to support the culture of said aerobic and anaerobic microorganisms.
Description brève des figuresBrief description of the figures
Les buts, objets et caractéristiques de l'invention apparaîtront plus clairement à la lecture de la description qui suit faite en référence aux dessins dans lesquels, La figure 1 est un bloc diagramme d'une station d'épuration incorporant un réacteur de traitement biologique selon l'invention, la figure 2 est une vue en coupe d'une cuve de prétraitement pouvant être utilisée en combinaison avec le réacteur de traitement biologique selon l'invention,The aims, objects and characteristics of the invention will appear more clearly on reading the following description made with reference to the drawings in which, FIG. 1 is a block diagram of a treatment plant incorporating a biological treatment reactor according to the invention, FIG. 2 is a sectional view of a pretreatment tank which can be used in combination with the biological treatment reactor according to the invention,
La figure 3 représente une coupe transversale de la cuve de pré-traitement , représentée sur la figure 3, selon l'axe A- A de la figure 2 ,FIG. 3 represents a cross section of the pre-treatment tank, represented in FIG. 3, along the axis A- A of FIG. 2,
La figure 4 est une représentation schématique du réacteur de traitement biologique selon l'invention.Figure 4 is a schematic representation of the biological treatment reactor according to the invention.
Description détaillée de l'inventionDetailed description of the invention
Une station d'épuration des eaux usées conforme à l'invention représentée schématiquement sur la figure 1, comprend un ensemble de pré-traitement 10 permettant la dissolution ou la dégradation en fines particules des matières solides contenues dans l'effluent arrivant du collecteur 11, un réacteur biologique 12 dans lequel est traité l'effluent et un clarificateur 14 destiné à séparer par sédimentation les boues issues du réacteur de l'eau traitée. La station comprend en outre un silo à boues 16 dont la sortie est composée d'une partie liquide recyclée à l'entrée de la cuve de pré-traitement et d'une partie contenant les boues à évacuer. L'effluent est acheminé de l'ensemble de pré-traitement au réacteur par un conduit 13 et du réacteur au clarificateur par un conduit 15. Du clarificateur 14, les eaux épurées sont rejetées dans la nature par la sortie 17, et du silo à boues 16, les boues épaissis sont retirées par la sortie 19.A wastewater treatment plant in accordance with the invention shown diagrammatically in FIG. 1, includes a pre-treatment unit 10 allowing the dissolution or degradation into fine particles of the solid materials contained in the effluent arriving from the collector 11, a biological reactor 12 in which the effluent is treated and a clarifier 14 intended to separate by sedimentation the sludges from the reactor from the treated water. The station also includes a sludge silo 16, the outlet of which consists of a liquid part recycled at the inlet of the pre-treatment tank and a part containing the sludge to be removed. The effluent is conveyed from the pre-treatment unit to the reactor by a line 13 and from the reactor to the clarifier by a line 15. From the clarifier 14, the purified water is discharged into nature through the outlet 17, and from the silo to sludge 16, the thickened sludge is removed through outlet 19.
En référence à la figure 2, l'ensemble de prétraitement selon l'invention est une cuve 10 de préférence maçonnée, à fond plat et dont les dimensions varient selon la quantité d'eaux usées domestiques à gérer. Elle est séparée en deux bassins 22 et 24, par une cloison centrée verticalement. La cloison est composée, de bas en haut, d'une première cloison fixe et étanche 26, d'une paroi perméable et mobile 28 et d'une seconde cloison fixe et étanche 30. Les trois parties qui composent la cloison centrale représentent chacune environ un tiers de la hauteur totale de la cloison.Referring to Figure 2, the pretreatment assembly according to the invention is a tank 10 preferably masonry, flat bottom and whose dimensions vary according to the amount of domestic wastewater to manage. It is separated into two basins 22 and 24, by a partition centered vertically. The partition is composed, from bottom to top, of a first fixed and waterproof partition 26, of a permeable and movable wall 28 and of a second fixed and waterproof partition 30. The three parts that make up the partition central each represent about a third of the total height of the partition.
L'effluent contenant les eaux usées domestiques, arrive dans le bassin 22 par un collecteur 11. Les matières contenues dans l'effluent ont des densités différentes et par conséquent les matières de densité élevée comme les sables et les matières lourdes ont tendance à se déposer dans la partie basse du bassin alors que les matières à faible densité comme les graisses et les mousses remontent dans la partie haute du bassin. La majeure partie de l'effluent se trouve donc dans la partie centrale du bassin 22 et migre vers le bassin 24 en passant par la paroi perméable 28. L'effluent se trouvant dans le bassin 22 est évacué vers le réacteur biologique au moyen d'une pompe hydraulique 32 et des conduits 34 et 13. Ce pompage crée donc naturellement un flux de l'effluent du bassin 22 vers le bassin 24 à travers la paroi perméable 28.The effluent containing the domestic wastewater, arrives in the basin 22 through a collector 11. The materials contained in the effluent have different densities and consequently the materials of high density such as sands and heavy materials tend to deposit in the lower part of the basin while low density materials such as grease and moss go up in the upper part of the basin. The major part of the effluent is therefore in the central part of the basin 22 and migrates towards the basin 24 via the permeable wall 28. The effluent being in the basin 22 is evacuated towards the biological reactor by means of a hydraulic pump 32 and conduits 34 and 13. This pumping therefore naturally creates a flow of effluent from the basin 22 to the basin 24 through the permeable wall 28.
Du fait que la composition et le volume de l'effluent varient selon les heures de la journée, il est nécessaire de disposer d'un système de régulation de débit afin de maintenir dans la cuve une quantité d' effluent telle que la surface de l'effluent se trouve toujours au niveau de la seconde cloison fixe et étanche 30. La régulation du débit consiste à renvoyer vers le bassin 22 une portion de l'effluent du bassin 24 au moyen de la pompe .hydraulique 32 et des conduits 34 et 40 alors qu'une autre portion de l'effluent pompé au moyen de la pompe hydraulique 32 (ou d'une autre pompe) est envoyé dans le réacteur par le conduit 13. Ce recyclage constitue donc un reflux de l'effluent du bassin 24 au bassin 22 qui atténue les flux du bassin 22 au bassin 24 à travers la paroi perméable 28 et qui contribue à l'homogénéisation de l'effluent. A noter qu'une vanne réglée électromécaniquement 38, permet de stopper le renvoi de l'effluent du bassin 24 au bassin 22 et donc de réguler le débit lors d'une forte augmentation du débit d' effluent entrant. De plus, cette vanne est réglée afin de laisser un laps de temps entre le reflux dans le premier bassin 22 et l'aspiration vers le réacteur de traitement permettant ainsi aux matières non dégradées de trouver leur place dans le bassin 22.Since the composition and the volume of the effluent vary according to the hours of the day, it is necessary to have a flow control system in order to maintain in the tank an amount of effluent such as the surface of the effluent is always at the level of the second fixed and watertight partition 30. The regulation of the flow consists in returning towards the basin 22 a portion of the effluent of the basin 24 by means of the hydraulic pump 32 and the conduits 34 and 40 while another portion of the effluent pumped by means of the hydraulic pump 32 (or of another pump) is sent into the reactor via the pipe 13. This recycling therefore constitutes a reflux of the effluent from the basin 24 to the basin 22 which attenuates the flows from basin 22 to basin 24 through the permeable wall 28 and which contributes to the homogenization of the effluent. Note that an electromechanically adjusted valve 38 makes it possible to stop the return of the effluent from the basin 24 to the basin 22 and therefore to regulate the flow during a sharp increase in the flow of incoming effluent. In addition, this valve is adjusted to allow a period of time between reflux in the first tank 22 and the suction to the treatment reactor thus allowing the non-degraded materials to find their place in the tank 22.
Le système de régulation de débit proprement dit comprend un système de contrôle électronique 44 programmable relié à au moins un capteur de niveau 42 du type capteur à mercure par exemple, à la ou les pompe (s) hydraulique (s) 32 et à l' électrovanne 38. Des contacts de niveau de sécurité peuvent également être reliés au système de contrôle afin de prévenir tout dysfonctionnement du dispositif, panne d'une pompe par exemple. Le système de contrôle électronique 44 peut agir par le biais d'un automate, donc sans intervention humaine, selon un certain nombre de consignes telles que le moment de la journée, la saison, les quantités d' effluent entrant et/ou transférés vers les étapes suivantes du traitement... Le système de régulation est programmé de façon à recevoir les paramètres inhérents à la station d'épuration à contrôler par l'intermédiaire de cartes imprimés préalablement établies selon les besoins de la commune.The flow control system proper comprises a programmable electronic control system 44 connected to at least one level sensor 42 of the mercury sensor type for example, to the hydraulic pump (s) 32 and to the solenoid valve 38. Safety level contacts can also be connected to the control system in order to prevent any malfunction of the device, breakdown of a pump for example. The electronic control system 44 can act by an automaton, therefore without human intervention, according to a certain number of instructions such as the time of the day, the season, the quantities of effluent entering and / or transferred to the following stages of treatment ... The regulation system is programmed to receive the parameters inherent to the treatment plant to be controlled by means of printed cards previously established according to the needs of the municipality.
Une caractéristique du système de pré-traitement selon l'invention est de traiter au maximum l'effluent pour le rendre le plus homogène possible. C'est ce que permet le conduit 50 de renvoi de l'effluent (issu du conduit 40) illustré sur la figure 3, dont la sortie se trouve dans la partie basse du bassin 22. Ceci créé un tourbillon qui brasse les parties lourdes ou solides à densité élevée se trouvant dans la zone 54 et les réduit en fines particules de façon à ce qu'elles se dissolvent ou qu'elles soient entraînées facilement dans l'effluent liquide en traversant la paroi 28. A noter qu'un deuxième conduit de renvoi 52A characteristic of the pre-treatment system according to the invention is to treat the effluent as much as possible to make it as homogeneous as possible. This is what allows the pipe 50 for returning the effluent (coming from the pipe 40) illustrated in FIG. 3, the outlet of which is located in the lower part of the basin 22. This creates a vortex which stirs the heavy parts or high density solids located in zone 54 and reduces them to fine particles so that they dissolve or are easily entrained in the liquid effluent by crossing the wall 28. Note that a second conduit reference 52
(issu du conduit 40) vers le bassin 22 a sa sortie située dans la partie haute du bassin 22 ceci afin de créer un remous dans les matières flottantes se trouvant dans la zone 56. Une partie des matières flottantes ainsi remuées, comme les mousses, coule vers le fond. Les graisses, huiles et hydrocarbures, de par leur nature et par l'effet du mouvement hydraulique créé par le flux et le reflux, se déposent sur les parois de la cuve de pré-traitement, formant ainsi un film isolant interdisant toute pénétration d'oxygène et favorisant la fermentation anaérobie et par conséquent le déroulement des différentes étapes aboutissant à la méthanogénèse c'est à dire à la transformation des matières organiques lipidiques en méthane et dioxyde de carbone .(from conduit 40) towards the basin 22 at its outlet situated in the upper part of the basin 22 this in order to create a swirl in the floating materials being in the zone 56. A part of the floating materials thus stirred, such as the foams, sinks to the bottom. Fats, oils and hydrocarbons, by their nature and by the effect of hydraulic movement created by the ebb and flow, is deposited on the walls of the pre-treatment tank, thus forming an insulating film preventing any penetration of oxygen and promoting anaerobic fermentation and therefore the progress of the various stages leading to the methanogenesis, ie the transformation of lipid organic matter into methane and carbon dioxide.
L'effluent résultant de la cuve de pré-traitement (aussi appelé liqueur) est envoyé par l'intermédiaire de la pompe hydraulique, dans le réacteur de traitement 14. En référence à la figure 4, le réacteur de traitement est un bassin dans lequel un certain nombre de disques 60-1 à 60-3 à demi immergés dans l'effluent 64 à traiter tournent lentement autour d'un axe 62 à une vitesse de l'ordre de 1 à 2 tours par minute. Les disques, de 2m de diamètre environ et dont l'épaisseur n'excède pas 1 cm (de préférence 5 mm) sont formés préférentiellement de deux plaques circulaires 70 et 72 sensiblement parallèles et séparées par un matériau cellulaire 74 à cellules ouvertes permettant à l'effluent d'être brassé et ainsi d'être oxygéné et homogénéisé. En effet, l'air ambiant prisonnier des cellules des disques pénètre en grande quantité dans l'effluent. A l'interface des deux fluides air/effluent , l'effluent se sature en oxygène, la diffusion de l'oxygène s'amorce alors vers les couches plus profondes de l'effluent. De plus, une quantité d' effluent circule elle- même dans les cellules ou alvéoles des disques et est d'autant plus brassée et oxygénée. Les disques peuvent avoir une forme autre que circulaire sans sortir du cadre de l'invention. Selon un mode de réalisation préféré, les disques sont en polypropylène. Ce matériau présente entre autres, les deux avantages suivants : sa faible densité qui réduit son poids et sa faible conductivité thermique qui participe à la non- dispersion de la chaleur. De plus, la structure creuse des disques allège également considérablement le support. L'effluent arrive d'un côté du réacteur par le conduit 13 et ressort du côté opposé du réacteur par la sortie 15 par gravité, la sortie 15 étant située sensiblement au niveau de l'axe 62 des disques afin de maintenir constant le niveau d' effluent dans le réacteur. Ainsi, l'entrée et la sortie de l'effluent créent un flux de l'effluent d'un bout à l'autre du réacteur.The effluent resulting from the pre-treatment tank (also called liquor) is sent via the hydraulic pump, to the treatment reactor 14. With reference to FIG. 4, the treatment reactor is a basin in which a certain number of discs 60-1 to 60-3 half immersed in the effluent 64 to be treated rotate slowly around an axis 62 at a speed of the order of 1 to 2 revolutions per minute. The discs, about 2m in diameter and whose thickness does not exceed 1 cm (preferably 5 mm) are preferably formed from two circular plates 70 and 72 substantially parallel and separated by a cellular material 74 with open cells allowing the 'effluent to be stirred and thus to be oxygenated and homogenized. In fact, the ambient air trapped in the disc cells enters the effluent in large quantities. At the interface of the two air / effluent fluids, the effluent becomes saturated with oxygen, the diffusion of oxygen then begins towards the deeper layers of the effluent. In addition, a quantity of effluent itself circulates in the cells or alveoli of the discs and is all the more stirred and oxygenated. The discs can have a shape other than circular without departing from the scope of the invention. According to a preferred embodiment, the discs are made of polypropylene. This material has, among other things, the following two advantages: its low density which reduces its weight and its low thermal conductivity which contributes to the non-dispersion of heat. In addition, the hollow structure of the discs also considerably lightens the support. The effluent arrives on one side of the reactor via the conduit 13 and leaves the opposite side of the reactor via the outlet 15 by gravity, the outlet 15 being situated substantially at the level of the axis 62 of the discs in order to keep the level d constant. 'effluent in the reactor. Thus, the inlet and the outlet of the effluent create a flow of the effluent from one end to the other of the reactor.
Les deux faces des disques servent de support aux micro-organismes, notamment des bactéries aérobies et anaérobies qui vont alors s'alimenter de la charge polluante de l'effluent 64. Cette technique de "culture fixée" utilise la capacité qu'ont la plupart des microorganismes à produire des exo-polymères permettant leur fixation sur des supports très divers pour former un bio- film.The two faces of the discs serve as a support for microorganisms, in particular aerobic and anaerobic bacteria which will then feed on the pollutant load of effluent 64. This technique of "fixed culture" uses the capacity that most have microorganisms to produce exo-polymers allowing their fixation on very diverse supports to form a biofilm.
La colonisation d'un disque commence sur un certain nombre de sites privilégiés, ces sites s'étendant progressivement jusqu'à former un bio-film qui se développe en continu jusqu'à recouvrement de la surface totale des deux faces du disque par une couche monocellulaire. A partir de ce moment, la croissance est continue par production de nouvelles couches qui viennent recouvrir la couche initiale. Il s'effectue donc une stratification d'un certain nombre de couches de culture de telle façon que l'oxygène qui diffuse à travers l'épaisseur du bio-film n'atteigne pas la couche la plus profonde. La colonisation des disques ne s'effectue pas à l'intérieur des cellules ou alvéoles puisque celles-ci sont lavées par le passage de l'effluent au cours de la rotation des disques, empêchant ainsi tout développement bactériologique. Au final, les faces du disque sont donc recouvertes d'une couche de bactéries anaérobies et d'une couche de bactéries aérobies. En milieu aérobie, une partie de la matière organique contenue dans l'effluent à traiter est consommée grâce à l'oxygène dissous dans l'effluent par les bactéries aérobies et dégradée en biomasse et en dioxyde de carbone. En milieu anaérobie, une autre partie de la matière organique contenue dans l'effluent est consommée à l'abri de l'oxygène par les bactéries anaérobies et dégradée en biomasse, en méthane et en dioxyde de carbone. Les microorganismes qui constituent la couche de bactéries aérobies, consomment de l'oxygène pour leur besoin énergétique, leur reproduction par division cellulaire appelée synthèse bactérienne et leur respiration endogène. Ces besoins en oxygène sont assurés en partie par la rotation des disques à demi immergés qui permettent de mettre en contact les bactéries aérobies alternativement avec la matière organique à dégrader puis avec l'oxygène présent dans l'air ambiant. Ils sont également assurés par la forme alvéolée des disques qui permet l'oxygénation de l'effluent. A noter que le brassage de l'effluent par les disques s'effectue sensiblement dans des plans verticaux parallèles aux disques et donc perpendiculairement au flux traversant de 1' effluent .The colonization of a disc begins on a certain number of privileged sites, these sites gradually extending until forming a bio-film which develops continuously until covering of the total surface of the two faces of the disc by a layer single cell. From this moment, the growth is continuous by production of new layers which come to cover the initial layer. A number of culture layers are therefore stratified in such a way that the oxygen which diffuses through the thickness of the biofilm does not reach the deepest layer. The colonization of the discs does not take place inside the cells or alveoli since they are washed by the passage of the effluent during the rotation of the discs, thus preventing any bacteriological development. In the end, the faces of the disc are therefore covered with a layer of anaerobic bacteria and a layer of aerobic bacteria. In an aerobic environment, part of the organic matter contained in the effluent to be treated is consumed thanks to the oxygen dissolved in the effluent by aerobic bacteria and degraded into biomass and carbon dioxide. In anaerobic environment, another part of the matter organic matter contained in the effluent is consumed away from oxygen by anaerobic bacteria and degraded in biomass, methane and carbon dioxide. The microorganisms that make up the layer of aerobic bacteria consume oxygen for their energy needs, their reproduction by cell division called bacterial synthesis and their endogenous respiration. These oxygen requirements are met in part by the rotation of the half-immersed discs which allow aerobic bacteria to come into contact alternately with the organic matter to be degraded and then with the oxygen present in the ambient air. They are also provided by the honeycomb shape of the discs which allows the oxygenation of the effluent. Note that the mixing of the effluent by the discs is carried out substantially in vertical planes parallel to the discs and therefore perpendicular to the flow passing through the effluent.
L'homogénéisation de l'effluent assurée par la rotation des disques assure un contact intime entre les éléments polluants et les bactéries. De plus, l'apport en oxygène également assuré par la rotation des disques évite un équipement supplémentaire de type compresseur ou aérateur ou de tout autre système permettant le brassage, ou un procédé de cascade ou de ruissellement. En effet, la faible oxygénation de l'effluent engendrerait la formation de nitrates et l'accumulation de phosphates, ce qui impliquerait des étapes supplémentaires de dénitrification et de dephosphatation étant donné que ces produits à haute dose sont très toxiques. Les variations de charge des matières organiques à dégrader sont lissées par le principe d'homogénéisation et le système de régulation de la cuve de pré-traitement. Cependant, dans le cas d'une très forte augmentation du débit et donc de la charge organique, la pellicule biologique en activité sur les disques possède la propriété d'absorber une charge dix fois supérieure à la charge normale, sans altération de la qualité de l'eau en sortie. La charge dite "normale" est évaluée par un dimensionnement préalable effectué à partir d'un certain nombre de paramètres pour l'implantation de chaque station d' épuration. La masse biologique présente sur les disques est également en mesure d'absorber et de digérer les molécules complexes que constituent les hydrocarbures, les graisses et autres matières grasses non absorbées par le prétraitement. Ces molécules arrivant dans le réacteur sont condamnées à se déposer sur les disques lors de leur rotation, ce qui permet aux bactéries en activité sur les disques de s'alimenter en proportion optimale de cette pollution. Le système de traitement à réacteur biologique selon l'invention est capable d'absorber jusqu'à 100 mg de graisse par litre d' effluent alors que les proportions estimées dans les rejets domestiques ne dépassent jamais 40 à 60 mg par litre.The homogenization of the effluent ensured by the rotation of the discs ensures intimate contact between polluting elements and bacteria. In addition, the oxygen supply also ensured by the rotation of the discs avoids additional equipment of the compressor or aerator type or any other system allowing mixing, or a cascade or trickling process. Indeed, the low oxygenation of the effluent would cause the formation of nitrates and the accumulation of phosphates, which would imply additional stages of denitrification and of phosphating since these products in high doses are very toxic. The load variations of organic matter to be degraded are smoothed by the principle of homogenization and the regulation system of the pre-treatment tank. However, in the case of a very strong increase in the flow rate and therefore in the organic load, the biological film in activity on the discs has the property of absorbing a load ten times greater than the normal load, without altering the quality of the outlet water. The so-called "normal" load is evaluated by a preliminary dimensioning carried out from a certain number of parameters for the implantation of each treatment plant. The biological mass present on the discs is also able to absorb and digest the complex molecules that constitute hydrocarbons, fats and other fats not absorbed by the pretreatment. These molecules arriving in the reactor are condemned to deposit on the discs during their rotation, which allows the bacteria in activity on the discs to feed in optimal proportion of this pollution. The biological reactor treatment system according to the invention is capable of absorbing up to 100 mg of fat per liter of effluent while the proportions estimated in domestic discharges never exceed 40 to 60 mg per liter.
A l'issue de la phase de traitement dans le réacteur biologique, l'effluent dépollué est chargé de boues constituées des bactéries mortes et des matières inertes. Il est transféré au moyen de la sortie 15 dans un bassin ou clarificateur 14 où il est soumis à une décantation naturelle permettant la séparation des boues et de l'eau épurée. Ainsi, la décantation permet la clarification de l'effluent et 1 ' épaississement de la boue. Les boues biologiques sont en général floconneuses et d'une densité très voisine de celle de l'eau, et par conséquent, la durée de la décantation est un paramètre à prendre en compte dans le dimensionnement de la station d'épuration. La capacité de l'effluent à décanter, dépend d'un certain nombre de facteurs tels que : la présence de rejets industriels, la teneur en oxygène dissous, la variation de composition de la charge organique de l'effluent, la température, etc. La mesure de la vitesse ascensionnelle (ou vitesse d'ascension de l'eau par rapport à la boue) est un paramètre habituel des bassins de clarification. Les valeurs guides, sur des effluents domestiques varient en moyenne sur une journée selon que la charge organique est faible ou importante entre 0,3 m/h et 1,25 m/h. Le système de traitement selon l'invention, permet d'accepter la totalité de l'effluent arrivant à la station, de lisser les variations de charge de la matière organique par le principe d'homogénéisation et le système de régulation de la cuve de pré-traitement et par conséquent de réguler la production de boue dans le réacteur et d'apporter une grande quantité d'oxygène dissous grâce au réacteur à disques biologiques. Grâce à ces conditions d'épuration réalisées sur l'ensemble prétraitement et traitement, la vitesse ascensionnelle de la boue dans le clarificateur est fortement augmentée par rapport aux station d'épuration traditionnelles et atteint 2 à 2,5 m/h. Cette importante vitesse ascensionnelle de la boue permet de diminuer le volume du clarificateur et en particulier de diminuer sa surface, ce qui représente une répercussion non négligeable sur le coût d'investissement, tant au niveau du génie civil qu'à celui de l'emprise foncière. A l'issu du clarificateur, l'eau épurée est rejetée dans la nature tandis que les boues sont placées dans un silo à boues 16 fermé en attendant leur évacuation et/ou leur liquéfaction. Les boues peuvent avoir plusieurs destinations finales telles que la valorisation agricole, l'incinération ou la mise en décharge. Leur élimination des stations d'épuration traditionnelles représente, tous les trois mois environ, un coût de transport non négligeable. Les boues issues de la station d'épuration selon l'invention subissent une liquéfaction due à la composition même des boues. En effet, la combinaison du système de prétraitement et du réacteur telle que décrite ici produit des boues dont la composition n'est pas comparable aux boues produites dans les stations d'épuration traditionnelles. En effet, en plus des bactéries mortes et des matières inertes, les boues issues de la station d'épuration selon l'invention, contiennent des composés en faible quantité tels que des nitrates, des phosphates, des matières inorganiques et organiques qui, ensemble continuent à subir une dégradation de manière anaérobie. Ainsi, la fréquence de soutirage des boues du silo 16 est réduite par rapport à un procédé traditionnel. Afin d'augmenter la capacité de la station d'épuration, il est possible d'augmenter les volumes des bassins réalisant l'ensemble pré-traitement et traitement. Il est également possible de réaliser en parallèle plusieurs ensembles pré-traitement et réacteur de traitement dans la même station d'épuration.At the end of the treatment phase in the biological reactor, the depolluted effluent is loaded with sludge consisting of dead bacteria and inert materials. It is transferred by means of the outlet 15 into a basin or clarifier 14 where it is subjected to a natural decantation allowing the separation of the sludge and the purified water. Thus, the settling allows the clarification of the effluent and the thickening of the mud. Biological sludge is generally fluffy and has a density very close to that of water, and therefore, the duration of decantation is a parameter to take into account in the design of the treatment plant. The capacity of the effluent to settle, depends on a certain number of factors such as: the presence of industrial waste, the dissolved oxygen content, the variation in composition of the organic load of the effluent, the temperature, etc. The measurement of the ascent rate (or rate of ascent of the water in relation to the mud) is a common parameter in clarification tanks. The guide values for domestic effluents vary on average over a day depending on whether the organic load is low or high between 0.3 m / h and 1.25 m / h. The treatment system according to the invention makes it possible to accept all of the effluent arriving at the station, to smooth the variations in charge of organic matter by the principle of homogenization and the system for regulating the pre-treatment tank. -treatment and therefore regulate the production of sludge in the reactor and provide a large amount of dissolved oxygen through the biological disk reactor. Thanks to these purification conditions carried out on the pretreatment and treatment unit, the upward speed of the sludge in the clarifier is greatly increased compared to traditional treatment plants and reaches 2 to 2.5 m / h. This significant upward speed of the mud makes it possible to reduce the volume of the clarifier and in particular to decrease its surface area, which represents a non-negligible impact on the investment cost, both in terms of civil engineering and that of the right-of-way. land. At the end of the clarifier, the purified water is discharged into the environment while the sludge is placed in a closed sludge silo 16 while awaiting their evacuation and / or their liquefaction. The sludge can have several final destinations such as agricultural recovery, incineration or landfill. Their elimination from traditional treatment plants represents, every three months approximately, a significant transport cost. The sludge from the treatment plant according to the invention undergoes liquefaction due to the very composition of the sludge. Indeed, the combination of the pretreatment system and the reactor as described here produces sludges whose composition is not comparable to the sludges produced in traditional treatment plants. In fact, in addition to dead bacteria and inert materials, the sludge from the treatment plant according to the invention contains compounds in small quantities such as nitrates, phosphates, materials inorganic and organic which together continue to undergo anaerobic degradation. Thus, the frequency of withdrawal of the sludge from silo 16 is reduced compared to a traditional process. In order to increase the capacity of the treatment plant, it is possible to increase the volumes of the basins carrying out the pre-treatment and treatment unit. It is also possible to carry out several pre-treatment and treatment reactor sets in parallel in the same treatment plant.
Bien que le réacteur de traitement biologique selon l'invention soit de préférence utilisé avec un système de pré-traitement à deux bassins tel que décrit ci-dessus, il est également possible que ce même réacteur soit utilisé à la suite d'un pré-traitement classique sans pour autant sortir du cadre de l'invention. Although the biological treatment reactor according to the invention is preferably used with a two-tank pretreatment system as described above, it is also possible that this same reactor is used following a pre-treatment. conventional treatment without departing from the scope of the invention.

Claims

REVENDICATIONS
1. Station d'épuration des eaux usées comprenant un réacteur de traitement biologique chargé de traiter l'effluent comportant des éléments cylindriques fixés sur un axe de rotation (62) destinés à la culture de micro- organismes aérobies et anaérobies pour la dégradation des matières organiques contenues dans l'effluent, lesdits éléments cylindriques étant en partie immergés dans l'effluent et ayant des evidements, canaux, ou alvéoles de manière à permettre l'oxygénation de l'effluent, l'oxygénation des micro-organismes et le contact des microorganismes avec les matières organiques de l'effluent ; ladite station d'épuration étant caractérisée en ce que lesdits éléments cylindriques sont des disques minces (60-1 à 60-3) formés de deux plaques (70 et 72) sensiblement parallèles séparées par un matériau cellulaire (74) à cellules ouvertes, les faces externes des plaques servant de support à la culture desdits micro-organismes aérobies et anaérobies.1. Wastewater treatment plant comprising a biological treatment reactor responsible for treating the effluent comprising cylindrical elements fixed on a rotation axis (62) intended for the cultivation of aerobic and anaerobic microorganisms for the degradation of materials organic contained in the effluent, said cylindrical elements being partly immersed in the effluent and having recesses, channels, or cells so as to allow the oxygenation of the effluent, the oxygenation of microorganisms and the contact of microorganisms with organic matter from the effluent; said purification station being characterized in that said cylindrical elements are thin disks (60-1 to 60-3) formed by two substantially parallel plates (70 and 72) separated by a cellular material (74) with open cells, the external faces of the plates serving as support for the culture of said aerobic and anaerobic microorganisms.
2. Station d'épuration selon la revendication 1, dans lequel les disques sont en polypropylène .2. Treatment plant according to claim 1, in which the disks are made of polypropylene.
3. Station d'épuration selon la revendication 1 ou 2, comprenant un système de pré-traitement (10) des eaux usées en amont du réacteur de traitement biologique comportant une cuve de pré-traitement unique divisée en un premier sous-bassin (22) recevant les eaux usées non traitées et un second sous-bassin (24) envoyant l'effluent pré-traité vers ledit réacteur de traitement, les deux sous-bassins étant séparées par une paroi perméable (28) permettant le passage des eaux usées débarrassées des parties flottantes et des parties tombantes dudit premier sous-bassin vers ledit second sous-bassin et, des moyens de pré-traitement permettant l'élimination des parties flottantes et des parties tombantes sans avoir à les retirer de la cuve de pré-traitement (10) .3. Treatment plant according to claim 1 or 2, comprising a pre-treatment system (10) for the wastewater upstream of the biological treatment reactor comprising a single pre-treatment tank divided into a first sub-basin (22 ) receiving the untreated wastewater and a second sub-basin (24) sending the pre-treated effluent to said treatment reactor, the two sub-basins being separated by a permeable wall (28) allowing the passage of the discharged waste water floating parts and falling parts of said first sub-basin towards said second sub-basin and, pre-treatment means allowing the elimination of the parts floating and falling parts without having to remove them from the pre-treatment tank (10).
4. Station d'épuration selon la revendication 3, dans laquelle ladite cuve est séparée en deux bassins par une cloison, constituée de bas en haut d'une première partie étanche (26) , de ladite paroi perméable (28) et d'une seconde partie étanche (30) , créant un flux de l'effluent du bassin (22) au bassin (24) à travers ladite paroi perméable (28) .4. Treatment plant according to claim 3, in which said tank is separated into two basins by a partition, constituted from bottom to top of a first sealed part (26), of said permeable wall (28) and of a second sealed part (30), creating a flow of effluent from the basin (22) to the basin (24) through said permeable wall (28).
5. Station d'épuration selon la revendication 3 ou 4, dans laquelle la cuve de pré-traitement dispose d'un système de régulation de débit afin de maintenir dans ladite cuve une quantité d' effluent telle que la surface de l'effluent se trouve toujours au niveau de ladite seconde partie étanche (30) et ce, quel que soit le débit et la composition de l'effluent entrant.5. Treatment plant according to claim 3 or 4, wherein the pre-treatment tank has a flow control system in order to maintain in said tank an amount of effluent such that the surface of the effluent is is always found at said second sealed part (30), regardless of the flow rate and the composition of the incoming effluent.
6. Station d'épuration selon l'une des revendications 3 à 5, comprenant en outre un conduit6. Treatment plant according to one of claims 3 to 5, further comprising a conduit
(34,40) permettant de renvoyer au moyen d'au moins une pompe hydraulique (32) et via une électrovanne (38) , une portion de l'effluent du bassin (24) vers le bassin (22), le fonctionnement de ladite pompe et l'ouverture de ladite électrovanne étant sous le contrôle dudit système de régulation.(34.40) making it possible to return, by means of at least one hydraulic pump (32) and via a solenoid valve (38), a portion of the effluent from the basin (24) to the basin (22), the operation of said pump and the opening of said solenoid valve being under the control of said regulation system.
7. Station d'épuration selon l'une des revendications 3 à 6, dans laquelle le conduit (34,40) de renvoi de l'effluent du bassin (24) au bassin (22) se divise en deux conduits (50) et (52) dans le bassin (22) , la sortie dudit conduit (52) étant située à la hauteur de ladite première partie étanche (26) et la sortie dudit conduit (50) étant située à la hauteur de ladite seconde partie étanche (30) . 7. Treatment plant according to one of claims 3 to 6, in which the conduit (34.40) for returning the effluent from the basin (24) to the basin (22) is divided into two conduits (50) and (52) in the basin (22), the outlet of said conduit (52) being located at the height of said first sealed portion (26) and the outlet of said conduit (50) being located at the height of said second sealed portion (30 ).
8. Station d'épuration selon l'une des revendications 3 à 7, dans laquelle ledit système de régulation de débit comprend un système de contrôle électronique programmable (44) relié à un capteur (42) permettant de détecter le niveau de l'effluent dans la cuve .8. Treatment plant according to one of claims 3 to 7, wherein said flow control system comprises a programmable electronic control system (44) connected to a sensor (42) for detecting the level of the effluent in the tank.
9. Station d'épuration selon l'une des revendications 3 à 8, dans laquelle une portion de l'effluent se trouvant dans la cuve est envoyée vers le réacteur par un conduit (34,13) au moyen de ladite pompe hydraulique .9. Treatment plant according to one of claims 3 to 8, in which a portion of the effluent in the tank is sent to the reactor by a conduit (34,13) by means of said hydraulic pump.
10. Station d'épuration selon l'une des revendications 3 à 9, dans laquelle l'effluent en sortie dudit réacteur est placé dans un clarificateur (14) où il est soumis à une décantation naturelle permettant la séparation des boues et de l'eau épurée.10. Treatment plant according to one of claims 3 to 9, in which the effluent leaving said reactor is placed in a clarifier (14) where it is subjected to a natural decantation allowing the separation of the sludge and the purified water.
11. Station d'épuration selon la revendication 10, dans laquelle les boues issues dudit clarificateur (14) sont placées dans un silo à boues pour leur liquéfaction et leur évacuation.11. Treatment plant according to claim 10, in which the sludge from said clarifier (14) is placed in a sludge silo for their liquefaction and their evacuation.
12. Station d'épuration selon la revendication 4, dans laquelle la boue liquéfiée est réintroduite en entrée de la cuve de pré-traitement (10) . 12. Treatment plant according to claim 4, in which the liquefied sludge is reintroduced at the inlet of the pre-treatment tank (10).
PCT/FR2002/001565 2001-05-09 2002-05-07 Biological treatment reactor in a purification plant WO2002090269A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP02732855A EP1390304A1 (en) 2001-05-09 2002-05-07 Biological treatment reactor in a purification plant

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
FR0106123A FR2824548B1 (en) 2001-05-09 2001-05-09 WASTEWATER PRE-TREATMENT SYSTEM IN A PURIFICATION STATION
FR01/06123 2001-05-09
FR01/06125 2001-05-09
FR0106125A FR2824550B1 (en) 2001-05-09 2001-05-09 BIOLOGICAL TREATMENT REACTOR IN A PURIFICATION STATION

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CN117800485A (en) * 2024-03-01 2024-04-02 清大益天生物技术(北京)有限公司 Water treatment device for degrading organic matters by immobilized microorganism plates

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JPH09267098A (en) * 1996-03-29 1997-10-14 Chugoku Shii S K:Kk Rotating contact type sewage treating device utilizing soil bacteria
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Publication number Priority date Publication date Assignee Title
GB935162A (en) * 1961-03-06 1963-08-28 Hartmann Hans Improvements in or relating to sewage plant
US4399031A (en) * 1980-07-07 1983-08-16 Sekisui Kagaku Kogyo Kabushiki Kaisha Biological sewage treatment apparatus of the rotary disc type
JPS588587A (en) * 1981-07-07 1983-01-18 Keizo Sekine Closed activated-sludge system for treating organic waste water
FR2744034A1 (en) * 1996-01-29 1997-08-01 Bragoni Consultants Sarl Waste water pretreatment plant
JPH09267098A (en) * 1996-03-29 1997-10-14 Chugoku Shii S K:Kk Rotating contact type sewage treating device utilizing soil bacteria
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117800485A (en) * 2024-03-01 2024-04-02 清大益天生物技术(北京)有限公司 Water treatment device for degrading organic matters by immobilized microorganism plates

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