EP0484352A1

EP0484352A1 - Process, installation and reactor for biological treatment of waste water

Info

Publication number: EP0484352A1
Application number: EP90910545A
Authority: EP
Inventors: Eberhard Kuhn
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-07-28
Filing date: 1990-07-24
Publication date: 1992-05-13
Also published as: US5281335A; AU632154B2; DD296668A5; HUT69504A; WO1991001948A1; DE3925091A1; AU6031490A; DE3925091C2; CA2059638A1; JPH04506926A; HU905462D0

Abstract

Procédé pour le traitement biologique des eaux usées, caractérisé en ce qu'il comprend les opérations successives indiquées ci-après: mélange des eaux usées brutes admises dans le circuit, avec une boue activée renfermant une première biocénose chimico-organotrophe, dans un étage préliminaire anaérobie (AVB); séparation de la solution de la boue activée dans un bassin de décantation intermédiaire (ZKB); nitrification de la solution séparée, au moyen d'une deuxième biocénose chimico-lithotrophe dans un étage de nitrification (NIR) avec un milieu aérobie; nouveau mélange de la solution nitrifiée avec la boue activée renfermant la première biocénose chimico-organotrophe; dénitrification commune du mélange provenant de la solution et de la boue activée, dans un étage de dénitrification (DER) avec un milieu anoxique; aération en vue de l'obtention d'un milieu aérobie; séparation des eaux usées épurées de la boue activée dans un bassin de décantation finale (NKB); recyclage (Rue) de la boue activée vers l'étage préliminaire anaérobie (AVB).Process for the biological treatment of waste water, characterized in that it comprises the successive operations indicated below: mixing of the raw waste water admitted into the circuit, with an activated sludge containing a first chemo-organotrophic biocenosis, in a preliminary stage anaerobic (AVB); separation of the solution from the activated sludge in an intermediate settling tank (ZKB); nitrification of the separated solution, by means of a second chemico-lithotrophic biocenosis in a nitrification stage (NIR) with an aerobic medium; re-mixing the nitrified solution with the activated sludge containing the first chemico-organotrophic biocenosis; common denitrification of the mixture coming from the solution and the activated sludge, in a denitrification stage (DER) with an anoxic medium; aeration to obtain an aerobic environment; separation of purified waste water from activated sludge in a final settling tank (NKB); recycling (Street) of the activated sludge to the anaerobic preliminary stage (AVB).

Description

Process for the biological treatment of waste water and plant and reactor for carrying out the process

The invention relates to the purification of waste water by means of a continuous biotechnological process.

The treatment of wastewater to be cleaned comprises the basic procedural operations of conversion and separation of substances. Four areas of activity can be distinguished from each other: removal of organic substances (carbon degradation), oxidative conversion of the inorganic nitrogen compounds ammonium and nitrite to nitrate (nitrification), conversion of the nitrate and nitrite to gaseous nitrogen compounds (denitrification) and biological elimination of phosphorus without the use of external chemical precipitants.

To fulfill these tasks, special microorganisms are used that have the special skills required for converting substances. In a wastewater treatment plant, these specialized microorganisms should be available in as large a number as possible, so that high material conversion rates and thus efficient wastewater purification are achieved.

Since wastewater treatment plants are basically operated as open plants, the establishment of the required organism types cannot be achieved by adding a starter culture. choose. Rather, a large number of microorganisms are continuously introduced with the inflowing wastewater and from the surrounding atmosphere. It is therefore always a matter of dealing with different types of microorganisms which occur simultaneously and socialize in a biocenosis.

In order to control the settlement of special organism species, to offer the desired species within the community a multiplication advantage, i.e. to increase their population strength, and to finally create the conditions for efficient wastewater treatment, selectively acting processes must be carried out in several successive process stages drive conditions are set and maintained.

Methods for the biological purification of waste water are known, in which the activated sludge, which contains the necessary microorganisms in common, are kept in a biologically closed system. In the so-called main flow process, the aeration basin is preceded by an anaerobic mixing basin for raw sewage and recycled activated sludge separated from the cleaned sewage solution. In this anaerobic precursor, phosphate is redissolved, in order to subsequently be taken up more by the bacteria in the aerated aeration tank and to be removed from the system with the excess sludge. In addition to biological phosphorus elimination, the customary methods also include a stage in which nitrogen is broken down.

Characteristic values for such biotechnological processes for wastewater treatment are the following sum parameters, which each record a subset of the pollution contained in the wastewater:

- DOC (Dissolved Organic Carbon); the organically bound carbon contained in the solution. - BSB5; the oxygen consumed by the bacteria in a wastewater sample within 5 days.

- TKN (Total Kjeldahl Nitrogen); the sum of organically bound nitrogen fixed in ammonium.

The object of the present invention is to provide a further developed method for biological wastewater treatment, which is characterized by a higher denitrification capacity, a reduced concentration of nitrogen and phosphate in the discharge and a lower critical ratio BOD5 / TKN. The devices necessary for carrying out the improved method are also to be made available.

According to the invention, the ravage is solved by the method for biological treatment of waste water specified in claim 1. Process steps a) and b) and e) to h) are already known per se. However, the proposed process differs fundamentally from the main processes known to date in that the solution is separated from the activated sludge following the anaerobic precursor, the separate nitrification of the separated solution by means of a second, chemitrophotrophic biocenosis and the subsequent remixing of the nitrified Solution with the Bele _^ islamm, whose chemoorganotrophic biocenosis has not been subjected to nitrification. With regard to nitrification, the denitrification stage is downstream. The aeration of the denitrifying biocenosis takes place either after the denitrification in a separate, subsequent process step or already in the denitrification stage itself, for example by means of a NOx-controlled interval ventilation, and additionally in a subsequent further process step. The method according to the invention is based on the following functional principle:

The incoming raw wastewater is first brought into contact with a chemoorganotrophic first biocenosis under anaerobic conditions. Hydrolyzing and fermentative bacteria produce lower fatty acids from poly- and monomeric carbon compounds. Phosphate-redissolving bacteria store these fatty acids inside with the release of phosphate. This results in a selective separation of the waste water, the organically bound carbon (DOC) contained in the solution being largely reduced, while the nitrogen content is reduced and the phosphate content increases sharply.

In the second process step, the solution is separated from the activated sludge and thus also from the first biocenosis.

The separated solution is nitrified separately by means of a second, chemolithotrophic biocenosis. The course of the nitrification stage is then brought back into contact with the first, chemoorganotrophic biocenosis.

Now the carbon compounds stored in the P-back-dissolving bacteria are oxidized, nitrate serving as the electron acceptor. Part of the energy released in the process is used to absorb phosphates. At the same time, nitrogen and carbon are assimilated.

In the subsequent process step, the denitrified mixture of solution and activated sludge is aerated, so that an anaerobic environment is established. Further phosphate is removed from the solution. The process ends with the separation of the cleaned wastewater from the activated sludge, which is returned to the anaerobic precursor.

The nitrification of the solution separated according to the invention in connection with the downstream denitrification leads to a significant increase in the denitrification performance in comparison to the previously known main stream processes with simultaneous or upstream denitrification. This has the consequence that the effluent wastewater contains significantly smaller amounts of nitrogen and the critical ratio BOD5 / TKN is lower. When using the method according to the invention, the costs of the aeration required for carbon oxidation can also be minimized.

The proposed method can be used if extensive elimination of carbon in the anaerobic precursor is guaranteed. The prerequisite for this is that the BOD5 value for the incoming raw wastewater is not too high, since the capacity for storing carbon of the P-redissolving microorganisms is limited. However, the dirt concentrations usually found in municipal wastewater should be within the permissible range. In addition, the temporal distribution of the inflow loads should not show excessive peaks, since otherwise easily degradable carbon compounds will penetrate into the nitrification stage. Since, according to the invention, the nitrification stage is arranged before the denitrification stage and the aeration stage, the incoming raw sewage must have sufficient buffer capacity.

In an alternative embodiment of the method according to the invention, following the separate nitrification of the solution, instead of the common pure denitrification joint simultaneous denitrification of the solution and the activated sludge in alternating aerobic and anoxic environments. A residual nitrification / denitrification takes place here.

The task aimed at specifying a corresponding device for carrying out the proposed method is solved by the four-stage system for the biological treatment of waste water specified in claim 3. The use of anaerobic pre-tanks, intermediate settling tanks, nitrification reactors, denitrification reactors, secondary settling tanks, aeration devices and a sludge recirculation are known, taken on their own. What is new compared to the prior art, however, is the arrangement according to the invention of these components in a wastewater treatment plant, an essential feature being the provision of a sludge bypass through which the activated sludge is passed directly from the intermediate clarifier without prior aeration, that is to say bypassing it of the nitrification reactor, is passed into the denitrification reactor.

In the four-stage wastewater treatment plant proposed here as the first alternative to a process engineering implementation, the critical ratio BSB5 / TKN is relatively low, since the cascade-like arrangement of the individual components means that the reflux ratio is small and high denitrification rates can be achieved.

The splitting of the volume flows in the intermediate clarifier is characteristic of the plant according to the invention. The ratio between the volume flows of the solution fed to the nitrification stage and the activated sludge passed through the sludge bypass should be as large as possible, since then a high percentage of the nitrogen in the form of nitrate for the subsequent denitrification in the downstream Denitrification level is available. The ratio that can be achieved in practical operation is determined by the settling behavior of the activated sludge in the intermediate clarifier.

The provision of an aeration device for aeration of the mixture of solution and activated sludge after the denitrification is a further essential feature of the invention.

As a ventilation device, for example, a terminal aeration basin comes into question, which can also be integrated with the denitrification reactor in a common structural unit. The ventilation required for the temporary creation of an aerobic environment can also be carried out by means of a NOx-controlled oxygen interval ventilation.

In an alternative version of the. In accordance with the invention, a simultaneous denitrification reactor can be provided instead of the denitrification reactor, in which a simultaneous denitrification / residual nitrification of the mixture of solution and activated sludge takes place in an alternating aerobic and anoxic environment.

A fixed bed reactor, for example a trickling filter, has proven itself as the nitrification reactor; However, this can also be designed as an aeration stage with its own intermediate clarifier and sludge return. The denitrification reactor is expediently designed as a stirred tank reactor.

For the flow-moderate decoupling is advantageously Ausfüh¬ tion of the invention between the Zwischenklärbeck - ι and provided the nitrification reactor ^ ^{»umpensumpf.}

The invention has created a specially designed reactor specifically for the technical implementation of the proposed method in small plants. This, in the patent say 10 circumscribed reactor allows the settlement of the first chemoorganotrophic biocenosis on a submerged disc diving body, so that it can be referred to as a three-phase submerged reactor.

Characteristic of the three-phase submerged reactor according to the invention is the division of its reactor vessel into a first compartment, into which the inlet for the raw sewage flows, and into a second compartment that is as well separated from the flow as possible, into which a return for re-introducing the separately nitrified solution opens . Another essential feature is the arrangement of a ventilation device in the second compartment, by means of which an aerobic environment can be set locally or for a limited time.

The incoming raw wastewater is fed into the lower area of the first anaerobic compartment and flows upwards between the disks of the submerged disk submersible. The vegetation on the disc diving body, which represents the first chemoorganotrophic biocenosis, produces lower fatty acids from dissolved carbon compounds and stores them with the release of phosphate. This first compartment thus corresponds to the anaerobic antechamber in a conventional system with stirred tank reactors.

Primary sludge and excess sludge sink down within the first compartment, settle at the bottom of the reactor and enter the second compartment, under the very slowly rotating disc immersion body, in which there is anoxic environment _* -.

The supernatant solution, on the other hand, leaves the first anaerobic compartment via the outlet above and is fed to a separate nitrification. The course of this, The nitrification stage located half of the three-phase submerged reactor is then returned from below to the second anoxic compartment. Denitrification and phosphate uptake now take place here by means of the carbon compound stored in the anaerobic part and the reduction equivalents contained in the primary sludge. The thus denitrified wastewater solution flows upward within the second compartment and reaches its upper region, in which the aeration device is arranged. The oxygen entered there is used by the biocenosis located on the panes of the submersible body for the oxidation of stored carbon compounds, coupled with an absorption of phosphate.

The cleaned wastewater leaves the reactor through the outlet provided in the upper part of the second compartment and can, if necessary, be subjected to a clarification.

The three-phase submerged reactor proposed by the invention is distinguished by the following advantageous properties: it enables a P-resolving biocenosis to settle on solid surfaces, namely on the disks of the disc diving body. The energy input is relatively low in comparison to other systems. The primary sludge is used to optimize P elimination and denitrification. There is no need for complex sludge cycles.

In a preferred embodiment of the reactor according to the invention, the separating device is designed as separating rods which run essentially vertically and are arranged between the disks of the disk immersion body. These separating rods are expediently each with their upper end in one upper partition and anchored with its lower end in a lower partition. The film of biomass that forms on the separating rods and the disks of the disk immersion body not only serves for the biochemical conversion within the reactor, but also simultaneously seals the two compartments. A high quality of the compartmentalization is necessary, since the critical ratio BSB5 / TKN depends on it.

In a further development of the reactor according to the invention, a sludge channel is provided between the lower partition, in which the separating rods are anchored, and the bottom of the reactor vessel, through which primary sludge and excess sludge get from the first anaerobic compartment into the second anoxic compartment in a controlled manner. In order to maintain the compartment as far as possible, the arrangement of a sludge barrier on the inner wall of the reactor vessel below the inlet for raw waste water has proven itself. This mud barrier should reach close to the circumference of the diving body.

The provision of mixing waves below the immersed disk ensures adequate mixing of the solution and the activated sludge in the lower and middle reactor area.

In particular, an embodiment of the reactor is preferred in which the ventilation device is a rotating, semi-submersible submersible body, the disks of which are partially arranged between the disks of the submerged submersible body. Due to the rotation of the additional disc diving body, oxygen is introduced into the upper region of the second compartment, which is coupled with the biocenosis which is located on the discs of the diving body for the oxidation of stored carbon compounds Ingestion of phosphate. Appropriately, the submerged-lying disc diving body and the semi-submerged additional diving body have the same direction of rotation, whereby the additional diving body rotates many times faster than the very slowly rotating, submerged-lying diving body.

On the well-ventilated disks of the only half-immersed additional diver body, a (third) beauty biocenosis can advantageously be settled, which nitrifies ammonium still present in the solution.

Excess sludge formed during wastewater treatment can be removed from the reactor if an additional outlet for excess sludge is provided at the bottom of the reactor vessel.

The system specified in claim 20 also serves to carry out the method according to claim 1 for the biological treatment of waste water. This plant contains the three-phase submerged reactor described above as a core and represents an alternative to the technical implementation specified in claim 3 with conventional individual components.

Within the specially designed three-phase submerged reactor, the pretreatment of the incoming raw sewage takes place by contacting the first chemoorganotrophic biocoenosis in the first compartment, which represents the anaerobic precursor, and the subsequent separation of the solution from the activated sludge. The nitrification reactor connected between the outflow of the first compartment and the return flow into the second compartment contains the second, chemolithotrophic biocenosis by means of which the separated solution is nitrified separately. The subsequent common denitrification of the solution mixed again with the activated sludge takes place in the second compartment of the three-phase submerged reactor. After ventilation in the upper part of the second compartment, the solution becomes the wastewater purified to this extent is again separated from the activated sludge which remains in the reactor vessel and can, if appropriate, be fed to a downstream clarifier. The invention is explained in more detail below with reference to the accompanying drawings. Show it:

Figure 1 shows a method for the biological treatment of waste water, in a schematic diagram;

FIG. 2 shows a first plant for the biological treatment of waste water, in a schematic representation;

FIG. 3 shows a three-phase submerged reactor for the biological treatment of waste water, in a vertical section;

Figure 4 shows the colonization of the reactor of Figure 3 with microorganisms;

Figure 5 shows the milieu zoning within the reactor of Figure 3;

6 shows the reactor of FIG. 3 as part of a second alternative plant for the biological ^■ treatment of waste water, in a schematic representation.

In Figure 1, the inventive method for the biological treatment of waste water is shown in a schematic diagram. It is a main flow process. The incoming raw waste water is mixed in an anaerobic preliminary stage with activated sludge, which contains a first chemoorganotrophic biocenosis I. The solution is then separated from the activated sludge. The separated solution is brought into contact with a second chemolithotrophic biocenosis II in a subsequent nitrification stage in which the aerobic environment prevails. The activated sludge is led past this nitrification stage. In the next process step, the separately nitrified solution is mixed again with the activated sludge which contains the biocoenosis I. A common denitrification of the mixture of solution and activated sludge now takes place in an anoxic environment. This is followed by a simultaneous denitrification stage in which aerobic and anoxic environments are alternately set by interval ventilation. A residual nitrification or denitrification thus takes place simultaneously. The cleaned wastewater is separated from the activated sludge and leaves the system as a drain. The activated sludge, and thus the biocoenosis I, is returned to the anaerobic preliminary stage.

The plant shown schematically in FIG. 2 represents a first alternative of a technical implementation of the method explained above with reference to FIG. 1 using conventional reactors.

The incoming raw sewage is first placed in a fully mixed anaerobic basin AVB, which is designed as a stirred tank reactor, and mixed there with the first chemoorganotrophic biocenosis I. The activated sludge settles in a subsequent intermediate clarifier ZKB. The supernatant solution flows into a pump sump PS and from there is passed into a nitrification reactor NIR. A fixed bed reactor is used here as the nitrification reactor NIR, for example, a trickling filter on which the second chemolithothrophic biocenosis II is located. This is followed by a denitrification reactor DER, into which the separately nitrified solution is passed.

The activated sludge deposited at the bottom of the intermediate clarification basin ZKB is pumped through a sludge bypass bypass, ie bypassing the nitrification reactor NIR, into the denitrification reactor DER. After the common denitrification of the solution and the activated sludge added again, the biocenosis II is aerated in a downstream terminal aeration tank TBB. Alternatively, the aeration device can also be integrated in the form of a NOx-controlled oxygen interval ventilation (not shown) in the denitrification reactor DER, which thus becomes a simultaneous denitrification reactor with an alternating aerobic and anoxic environment.

The final stage is a secondary clarifier NKB, in which the solution is separated from the activated sludge again. The cleaned wastewater leaves the plant via the outlet, while the activated sludge that is deposited is pumped back into the anaerobic antechamber AVB via a sludge return Rü and thus remains largely in the plant. Excess sludge US is withdrawn from the plant via a drain at the secondary clarifier NKB.

FIG. 3 shows a specially designed three-phase submerged reactor 3PSR, which is used to carry out the method for biological treatment of waste water described with reference to FIG.

In a reactor vessel 1, a submerged disc immersion body 2 is rotatably mounted about its axis of rotation 3. The inside of the reactor vessel 1 is vertically between the Discs of the disc diving body 2 extending T-rods 4 divided into a first compartment KI and a second compartment KII. The dividing bars 4 are each anchored in an upper dividing wall 5 and a lower dividing wall 6.

An inlet 7 for raw waste water opens into the lower part of the first compartment KI. At the upper part of the first compartment KI, a first drain 8 is provided for the solution. A return line 9 opens into the lower part of the second compartment KII for reintroduction of the solution nitrified separately outside the reactor. In the upper part of the second compartment KII, a second outlet 10 is provided for the cleaned waste water. Finally, an outlet 11 for excess sludge is arranged at the bottom of the reactor vessel 1.

On the inner wall of the reactor vessel 1, a sludge barrier 12 is arranged below the inlet 7, which reaches close to the circumference of the disc diving body 2. The lower dividing wall 6, which is rounded at its lower end,, together with the sludge barrier 12, delimits a sludge channel 13 through which activated sludge from the first compartment KI into the second compartment KII below the window thaw. body 2 can pass through.

The mixing of the wastewater to be cleaned and the activated sludge suspended in this in the lower part of the reactor are carried out by mixing shafts 14 and 15, which are arranged horizontally below the disc immersion body 2.

In the upper part of the second compartment KII an additional disc diving body 16 is arranged. Its axis of rotation 17 runs parallel to the axis of rotation 3 of the submerged immersion body 2 and is arranged approximately at the level of the reactor vessel 1. The discs of this additional disc The diving body 16 are thus semi-submerged and partially overlap with the disks of the submerged disc diving body 2. The semi-submerged additional diving body 16 and the submerged disc diving body 2 both rotate in the same counterclockwise direction. While the disc diving body ϊ ^* only makes one revolution about every 8 hours, the additional disc diving body 16 rotates comparatively quickly at one to two revolutions per minute.

The first chemoorganotrophic biocenosis I is located on the submerged disc immersion body 2 - compare FIG. 4. Primary and excess sludge settles in the lower region of the reactor. A third fining biocenosis III is located on the discs of the additional disc diving body 16.

The division of the interior of the reactor by means of the separating rods 4, between which the disks of the disk immersion body 2 rotate, serves for environmental zoning, as is shown in FIG. 5. Anaerobic environment prevails in the first compartment KI. In the lower and middle area of the opposite second compartment KII, apart from transition areas, there is essentially an anoxic environment. Due to the slow rotation of the disc diving body 2 and the characteristic miliezonation, the chemoorganotrophic biocenosis I (see FIG. 4) is subject to a cyclic change from anaerobic (approx. 3 hours), anoxic (approx. 3 hours) and aerobic (approx. 2 Hours) conditions.

A second technical implementation of the method for biological treatment of waste water shown in FIG. 1 is shown in FIG. The core of this plant is the three-phase submerged reactor 3PSR described above with reference to FIGS. 3, 4 and 5. In addition to the 3PSR reactor, the plant comprises a conventional fixed bed nitrification reactor NIR ¹ , which serves as a nitrification stage, and a secondary settling tank NKB '. The incoming raw wastewater reaches the lower region of the anaerobic first comparator KII of the 3PSR reactor via the inlet 7 (cf. FIG. 3) and flows upwards between the disks of its disc immersion body 2. The wastewater comes into contact with the biocenosis I under anaerobic conditions. Primary sludge and excess sludge from the anaerobic compartment KI pass through the sludge channel 13 into the second anoxic compartment KII. The waste water solution leaves the first compartment KI through the first outlet 8 at the top and is directed to the fixed bed nitrification reactor NIR ¹ .

The discharge of the fixed bed nitrification reactor NIR 'flows from below through the return 9 into the second compartment KI_, which is anoxic in this area. on. The common denitrification of the solution and the activated sludge now takes place here. The solution flows upward within the second compartment KII and reaches its upper area. As a result of the rotation of the additional disc diving body 16, oxygen is introduced there, so that an aerobic environment is established. At the same time, the fining biocoenosis III located on the panes of the additional pan body 16 nitrifies any ammonium still present.

The cleaned wastewater solution leaves the 3PSR reactor through its second outlet 10 above.

In the secondary clarifier NKB ¹ , activated sludge suspended in the wastewater solution settles down and can be removed from the plant as excess sludge US. Directory of reference characters

AVB anaerobic anteroom

ZKB intermediate clarifier

NIR nitrification reactor

THE denitrification reactor

SDR simultaneous denitrification reactor

NKB secondary clarifier

PS pump sump

Byp mud bypass

Rü sludge return

US excess mud

3PSR three-phase submerged reactor

AI First compartment

KII second compartment

1 reactor vessel

2 diving discs

3rd Axis of rotation (of 2)

4 dividing bars

5 Upper partition

6 Lower partition

7 inflow (in AI)

8 First process (from AI)

9 return (in KII)

10 second sequence (from KII)

11 excess sludge drain

12 mud barrier

13 mud channel

14 mixing shaft

15 ^• Mixing shaft

16 additional diving discs

17 axis of rotation (of 16)

NIR 'fixed bed nitrification reactor

NKB 'clarifier

Claims

1. Process for the biological treatment of waste water, with the successive process steps:

a) mixing the incoming raw sewage with activated sludge, which contains a first chemoorganotrophic biocenosis, in an anaerobic precursor;

b) separation of the solution from the activated sludge;

c) nitrification of the separated solution by means of a second, chemolithotrophic biocenosis in a nitrification stage with an aerobic environment;

d) remixing the nitrified solution with the activated sludge which contains the first chemoorganotrophic biocenosis;

e) joint denitrification of the mixture of solution and activated sludge in a denitrification stage with an anoxic medium;

f) ventilation to create an aerobic environment;

g) separation of the cleaned wastewater from the activated sludge;

h) return of the activated sludge to the anaerobic precursor.

2. The method according to claim 1, characterized by the step following the nitrification and replacing the denitrification:

e ') Joint simultaneous denitrification of the solution and the activated sludge in a simultaneous denitrification step with alternating aerobic and anoxic milieu.

3. Plant for the biological treatment of waste water according to the method given in claim 1, comprising:

a) a fully mixed anaerobic basin (AVB), into which an inlet for raw waste water flows and which contains the first chemoorganotrophic biocoenosis;

b) an intermediate chamber (ZKB) in which the activated sludge is separated from the solution;

c) a nitrification reactor (NIR) for separate nitrification of the separated solution, which contains the second chemolithotrophic biocenosis;

d) a denitrification reactor (DER) for the common denitrification of the solution and the re-added activated sludge;

e) a sludge bypass (bypass) through which the activated sludge from the intermediate clarifier (ZKB) is fed directly into the denitrification reactor (DNR);

f) an aeration device for aeration of the mixture of solution and activated sludge;

g) a subsequent secondary clarifier (NKB), in which the activated sludge is separated from the cleaned waste water; h) a sludge return (Rü) for returning the separated activated sludge from the secondary clarification tank (NKB) to the anaerobic antechamber (AVB).

4. Plant according to claim 3, characterized in that the ventilation device is a terminal aeration tank (TBB).

5. Plant according to claim 3, characterized in that the ventilation device is designed as a NOx-controlled oxygen interval ventilation.

6. Plant according to one of claims 3 to 5, characterized gekenn¬ characterized in that instead of the denitrification reactor (DER) is provided:

d ') a simultaneous denitrification reactor for simultaneous denitrification of the mixture of solution and activated sludge, in which there is an alternating aerobic and anoxic environment.

7. Plant according to one of claims 3 to 6, characterized gekenn¬ characterized in that the nitrification reactor (NIR) is designed as a fixed bed reactor.

8. Plant according to one of claims 3 to 7, characterized gekenn¬ characterized in that the denitrification reactor (DNR) is designed as a stirred tank reactor.

9. Plant according to one of claims 4 to 8, characterized gekenn¬ characterized in that a pump sump (PS) is provided between the intermediate clarifier (ZKB) and the nitrification reactor (NIR).

10. Three-phase submerged reactor (3PSR) for the biological treatment of waste water according to the method specified in claim 1, comprising:

- a reactor vessel (1);

- A Treinnvorrichtung that divides the inside of the reactor vessel (l) into a first compartment (KI) with an anaerobic environment and a second compartment (KII) with a predominantly anoxic environment;

- a submerged and slowly rotating disc diving body (2) which passes through the separating device and on which the first chemoorganotrophic biocenosis is located;

- An inlet (7) for raw waste water opening into the lower part of the first compartment (KI);

- A first outlet (8) for solution provided at the upper part of the second compartment (KI);

- A return (9) opening into the lower part of the second compartment (KII) for reintroducing the nitrified solution;

- A second outlet (10) provided for the cleaned waste water at the upper part of the second compartment (KII);

- A ventilation device arranged in the second compartment (KII).

11. Reactor according to claim 10, characterized in that the separating device is designed as separating rods (4) which run essentially vertically and are arranged between the disks of the disc diving body (2).

12. Reactor according to claim 11, characterized in that the separating rods (4) are anchored with their upper end in an upper partition (5) and with their lower end in a lower partition (6).

13. Reactor according to claim 12, characterized in that a sludge channel (13) for Belebt¬ sludge is provided between the lower partition (6) and the bottom of the reactor vessel (1).

14. Reactor according to one of claims 10 to 13, characterized in that on the inner wall of the reactor vessel

(1) a mud barrier (12) is arranged below the inlet (7), which reaches up to close to the circumference of the disc diving body (2).

15. Reactor according to one of claims 10 to 14, characterized in that below the disc diving body

(2) Mixing shafts (14, 15) are arranged.

16. Reactor according to one of claims 10 to 15, characterized in that the ventilation device is a rotating, semi-submersible additional submersible body (16) arranged in the upper part of the second compartment (KII), the disks of which are partly between the disks of the submerged submersible body (2) are arranged.

17. A reactor according to claim 16, characterized in that the submerged disc diving body (2) and the semi-submerged additional disc diving body (16) have the same direction of rotation.

18. Reactor according to claim 16 or 17, characterized in that a fining biocenosis is located on the disks of the semi-submersible additional disk immersion body (16).

19. Reactor according to one of claims 10 to 18, characterized gekenn¬ characterized in that an outlet (11) is provided for the excess sludge at the bottom of the reactor vessel (1).

20. Plant for the biological treatment of waste water according to the method specified in claim 1, comprising:

a) the three-phase submerged reactor (3PSR) according to one of claims 10 to 19;

b) a nitrification stage connected between the first outlet (8) from the first compartment (KI) and the return (9) into the second compartment (KII) of the three-phase submerged reactor (3PSR) for separate nitrification the separated solution which contains the second chemolithotrophic biocenosis.

21. Plant according to claim 20, characterized by:

c) a secondary clarifier (NKB ¹ ) downstream of the three-phase submerged reactor (3PSR).

22. Plant according to claim 20 or 21, characterized by:

d) an intermediate clarifier connected between the first compartment (KI) of the three-phase submerged reactor (3PSR) and the nitrification stage.

23. Plant according to one of claims 20 to 22, characterized gekenn¬ characterized in that the nitrification stage is designed as a fixed bed nitrification reactor (NIR ¹ ).

24. Plant according to one of claims 20 to 23, characterized gekenn¬ characterized in that the nitrification stage is formed as an aeration tank with its own intermediate clarification and sludge return.