EP0888256A1 - Procede et dispositif d'epuration des eaux usees - Google Patents

Procede et dispositif d'epuration des eaux usees

Info

Publication number
EP0888256A1
EP0888256A1 EP97906151A EP97906151A EP0888256A1 EP 0888256 A1 EP0888256 A1 EP 0888256A1 EP 97906151 A EP97906151 A EP 97906151A EP 97906151 A EP97906151 A EP 97906151A EP 0888256 A1 EP0888256 A1 EP 0888256A1
Authority
EP
European Patent Office
Prior art keywords
sludge
nitrification
denitrification
treatment
water
Prior art date
Legal status (The legal status 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 status listed.)
Ceased
Application number
EP97906151A
Other languages
German (de)
English (en)
Inventor
Friedrich Wagner
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Wehrle Werk AG
Original Assignee
Wehrle Werk AG
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
Application filed by Wehrle Werk AG filed Critical Wehrle Werk AG
Publication of EP0888256A1 publication Critical patent/EP0888256A1/fr
Ceased legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F11/00—Treatment of sludge; Devices therefor
    • C02F11/02—Biological treatment
    • C02F11/04—Anaerobic treatment; Production of methane by such processes
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/38—Treatment of water, waste water, or sewage by centrifugal separation
    • C02F1/385—Treatment of water, waste water, or sewage by centrifugal separation by centrifuging suspensions
    • 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
    • C02F3/30—Aerobic and anaerobic processes
    • C02F3/302—Nitrification and denitrification treatment
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F11/00—Treatment of sludge; Devices therefor
    • C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
    • C02F11/121—Treatment of sludge; Devices therefor by de-watering, drying or thickening by mechanical de-watering
    • C02F11/127—Treatment of sludge; Devices therefor by de-watering, drying or thickening by mechanical de-watering by centrifugation

Definitions

  • the invention relates to a process for the purification of wastewater, in which the wastewater is microbially converted by a biological treatment with activated sludge, the activated sludge is separated from the microbially converted waste water and subjected to a sludge treatment, the treated activated sludge Sludge water is withdrawn and return water obtained from the sludge water is returned to the biological treatment, and to a device for carrying out this method.
  • the activated sludge which has been separated off is subjected to the sludge treatment together with primary sewage sludge, and the sludge removed from this waste water sludge Mud water is returned directly to the biological treatment and passes through the latter together with the wastewater supplied to it.
  • This sludge water originating from the sludge treatment of the waste water sludge has a relatively high nitrogen content, as a result of which a high nitrogen input into the biological treatment takes place. So that the microbially converted wastewater separated from the wastewater dam can be discharged into a receiving water after the biological treatment, for example, its nitrogen content must be reduced to a low value according to the legal regulations. This can hardly be achieved with the direct return of the sludge water, especially when the biological treatment is used to a high degree.
  • the invention is based on the object of developing a method of the type mentioned at the outset such that the efficiency for nitrogen removal is increased and of specifying an apparatus for carrying out the method according to the invention.
  • this object is achieved according to the invention in that the sludge water is subjected to an microbial nitrification / denitrification treatment and the return water from the nitrification / denitrification treatment is separated off by centrifugation.
  • the nitrification / denitrification treatment results in a nitrogen removal from the sludge water of around 80 to 90%, but this can also be increased up to 100%.
  • the return water remaining after the nitrification / denitrification treatment therefore does not lead to excessive nitrogen input when it is returned to the biological treatment. In this way, the removal of nitrogen can be achieved with high room-specific degradation rates.
  • the microbial nitrification / denitrification processes for biomass efficiently and gently separated from the return water. This enables high biomass concentrations to be achieved, which are, for example, 5 to 10 al as high as in the known processes. Therefore, only a correspondingly small reaction volume is required.
  • the nitrification / denitrification treatment is carried out in a denitrification stage fed by the sludge water and in a nitrification stage downstream of the denitrification stage, from which the return water is separated off and from the one obtained during the nitrification process nitrogenous sludge-water mixture is returned to the denitrification stage.
  • the upstream connection of the denitrification stage compared to the nitrification stage is particularly favorable with regard to the reaction rate.
  • Optimal conditions are created in that from the nitrification stage downstream of the denitrification stage a multiple of the amount of sludge water supplied to the denitrification stage per unit of time is recycled in order to obtain a sufficient amount of nitrate for the denitrification.
  • the performance can also be increased further by connecting several cascades of denitrification and nitrification stages in series.
  • a further increase in performance can be achieved in that the nitrification stage is followed by a further denitrification stage from which the return water is separated. While around 80 to 90% of the nitrogen compounds are denitrified in the denitrification stage upstream of the nitrification stage, depending on the degree of recycle of the nitrogenous sludge, a further denitrification stage downstream of the nitrification stage can higher degree of nitrogen removal, up to 100%.
  • nitrogen is mainly in the form of urea and proteins. About 90% of urea, based on nitrogen, is already converted into ammonium in the sewer network and in the primary settling tank of the wastewater treatment plants. The conversion of the proteins is considerably more complicated over several phases of heterotrophic bacteria in the activated sludge of the biological treatment. In the end, however, the protein nitrogen is also in the form of ammonium. This phase of ammonification of the organically bound nitrogen therefore does not require any special process engineering equipment.
  • the nitrification of the ammonium is brought about by various aerobic chemilithotrophic microorganism types of the two genera Nitrosomonas and Nitrobacter under oxygen consumption, whereby the nitrogen is finally converted into the form of nitrites or nitrates.
  • air is therefore supplied for the treatment in the nitrification stage.
  • the nitrite and nitrate oxygen is used by facultative heterotrophic bacteria instead of dissolved oxygen as an electron acceptor under certain circumstances.
  • This respiration of oxidized nitrogen corresponds biochemically to oxygen respiration. It becomes effective to the extent that the proportion of dissolved oxygen is reduced. On the one hand, this makes it possible to recover part of the ventilation energy applied for the nitrification and, at the same time, releases the nitrogen in gaseous form through the nitrite and nitrate reduction.
  • Many facultative bacteria which are normally abundant in all activated sludge systems, can switch from oxygen respiration to nitrate respiration in an anoxic environment without difficulty. Electron donors are also required for nitrate respiration.
  • an expedient variant of the method according to the invention is that the denitrification treatment is carried out with the supply of an external carbon carrier.
  • Possible carbon carriers are, for example, methanol or acetic acid.
  • the method according to the invention is designed in such a way that the sludge treatment of the activated sludge has a fouling treatment.
  • the digestion treatment causes a partial decomposition of the activated sludge from the biological treatment with the formation of digestion gas.
  • the sludge water separated from the digested treatment of the activated sludge is subjected to the nitrification / denitrification treatment.
  • a plant according to the invention for carrying out the method according to the invention with a biological treatment device serving for the microbial conversion of the waste water by activated sludge, a separating device serving for separating the activated sludge from the microbially converted waste water, and a sludge treatment device serving for the treatment of the separated activated sludge , a device used for the removal of sludge from the treated activated sludge and a return circuit serving to feed the return water obtained from the removed sludge water into the biological treatment device is characterized in that in the return circuit a nitrifying agent charged on the inlet side with the sludge water cation / denitrification device is provided to the a separator is connected on the output side, at the one outlet of which the return water is obtained and the other outlet which supplies a concentrate is returned to the nitrification / denitrification device.
  • the separator in which the return water is separated from the solid constituents of the sludge active in the nitrification / denitrification device by centrifugal force, enables the required degree of separation and the pressures which occur to be set individually.
  • the separator is a plate centrifuge, preferably in the form of a nozzle separator or a nozzle separator.
  • a screening device is connected upstream of the separator. Furthermore, it is expedient to alternatively or additionally connect a cyclone separator.
  • a construction of the plant within the scope of the invention consists in that the nitrification / denitrification device has a denitrification tank, on the inlet side of which the sludge water is fed, to the outlet of which a nitrification tank is connected with its inlet, from which nitrogen-containing sludge obtained during the nitrification process Water mixture can be returned to the denitrification tank by means of a return path. While with low nitrogen loads in different areas of a single container it could be nitrified and denitrified at the same time or by targeted intermittent
  • the nitrification container and the denitrification container are provided as separate units, so that the optimal conditions for the respective processes can be set independently of one another.
  • FIG. 2 shows a more detailed illustration of a part of the scheme from FIG. 1 related to a nitrification / denitrification treatment
  • FIG. 3 shows a diagram corresponding to FIG. 2 of a special embodiment.
  • wastewater to be cleaned is introduced from a schematically illustrated inlet 1 via a rake 2 used to hold larger foreign bodies and a downstream sand trap 3 into a primary clarifier 4.
  • the pre-clarified wastewater passes from the pre-clarification tank 4 into a biological treatment facility, the core of which is an aeration tank 5, in which the contents of the wastewater are reacted microbially with activated sludge.
  • a return line 9 provided with a pump 8, the contents of the secondary clarifier 6, a partial stream can be returned to the entrance of the aeration tank 5.
  • the activated sludge separated from the microbial u-deposited wastewater is fed from the clarifier 6 to a sludge treatment device, the core of which is a digester 11.
  • a sludge treatment device the core of which is a digester 11.
  • Pre-treatment sludge from pre-treatment tank 4 can also be introduced into this digester 11 via a line 12.
  • the sewage sludge formed by the activated sludge drawn off via line 10 together with the primary sewage sludge taken off via line 12 undergoes a fermentation treatment in the digestion chamber 11, by which biogas is produced, which is withdrawn from the digestion chamber 11 via a line 13.
  • the digester 11 is followed by a device through which sludge water is extracted from the sewage sludge subjected to the digestion treatment.
  • This device has a thickener 14, a machine drain 15 and a drying device 16 connected in series.
  • the sludge water is increasingly removed from the treated sewage sludge.
  • the latter is composed of the digested water separated in the thickener 14 and obtained at an outlet 17, that in the mechanical dewatering 15, for example by filtration or centrifugation, which is obtained at an outlet 18 and the filtrate or centrate and the in the vapors separated from the dryer 16 and accumulating at an outlet 19.
  • the sewage sludge freed from the sludge water in this way is discharged from the dryer 16, as symbolically indicated at 20, as dried sludge.
  • the extracted sludge water is collected in a surge tank 21 connected to the outputs 17, 18 and 19. This is located in a recirculation circuit in which a nitrification / denitrification device 22, a separator 23 and the primary settling tank 4 are located, so that the return circuit leads back to the activation tank 5.
  • the nitrogen is biologically extracted from the sludge water, which has a high nitrogen load, by the action of microorganisms, in that it is released in gaseous form in molecular form and can, for example, be released into the atmosphere.
  • the separator 23 connected downstream of the nitrification / denitrification device 22 serves to separate the return water returned from the recirculation circuit to the biological treatment device from the bacterial sludge causing the nitrification / denitrification reactions, which separator 23 as a concentrate to the nitrification / denitrification device 22 is returned.
  • FIG. 2 shows, for a special embodiment, the part of a plant which corresponds to the scheme of FIG. 1 and which is related to the nitrification / denitrification treatment and the separation of the return water.
  • FIG. 2 to the left is the surge tank 21 of FIG. 1, which is fed with the sludge water at an inlet 24.
  • the nitrification / denitrification device 22 has a denitrification tank 27, which is charged with the sludge water, from the surge tank 21 via a feed line 25, into which a feed pump 26 is switched, to which a downstream nitrification tank 29 is connected via a discharge line 28 is connected with its entrance.
  • the amount returned via the return path 30 is selected to be significantly higher than the amount of sludge water newly flowing in via the feed line 25, for example the amount returned is approximately that Ten times the amount fed through the feed line 25.
  • the continuous process running between the denitrification container 27 and the nitrification container 29 advantageously achieves high nitrate or nitrite concentrations, as a result of which, in the denitrification, the nitrogen present in the oxidized form can be converted into gaseous molecular nitrogen at a high reaction rate.
  • the gaseous nitrogen produced in this way is discharged via an exhaust air line 31 which is connected to both the denitrification tank 27 and the nitrification tank 29.
  • a separating device 33 is connected to the nitrification tank 29 via an outlet line 32 and is used to separate the sludge formed by the microorganisms involved in the nitrification / denitrification reactions in the form of a concentrate from the return water, that from an outlet 34 of the separating device 33 is returned to the biological treatment facility.
  • This concentrate is returned to the nitrification tank 29 via a concentrate return line 36 provided with a concentrate return pump 35.
  • An excess concentrate can be removed through an excess sludge discharge line 37 branching off from the concentrate return line 36 and shown in broken lines and subjected to a concentrate or sludge treatment.
  • FIG. 2 An alternative further embodiment of the embodiment shown in FIG. 2 consists in that the nitrification container 29 is not connected directly to the separating device 33, but, as indicated by a line 38 shown in dashed lines, between the nitrification container 29 and the separation device 33 is connected to a further denitrification tank 39, which is also connected to the exhaust air line 31.
  • the degree of nitrogen removal that is in the inlet-side denitrification tank 27 can be after the degree of recirculation of the recirculation path 30, a denitrification of approximately 80 to 90% of the nitrogen compounds can be increased to up to 100%.
  • a carbon carrier for example methanol or acetic acid
  • a carbon carrier for example methanol or acetic acid
  • the denitrification container 27 can be selectively added to the denitrification container 27 as well as the nitrification container 29 and the optionally provided further denitrification container 39 from a carbon source 41.
  • the nitrification tank 29 and the optionally provided further denitrification tank 39 are connected via an air supply line 42 to a compressor 43 serving for the air supply.
  • the aeration represents the normal operation.
  • alternating operation between denitrification and nitrification could be carried out there by intermittent aeration, so that the two tanks 29 and 39 are both in the function of a denitrification part and also the function of a nitrification part can be used.
  • a further variety of the operating mode is created by a bypass line 44 which extends from the feed line 25 to the nitrification tank 29 and through which the sludge water can be introduced directly into the nitrification tank 29.
  • FIG. 3 differs from the embodiment shown in FIG. 2 only in the construction of the separating device 33, while with respect to all other elements labeled with the same reference symbols, there is complete agreement between FIG. 2 and FIG. 3 exists, so that in this respect reference is made to the description of FIG. 2.
  • Output of the nitrification / denitrification device 22 is first connected to a screening device 45 in the form of a rotary brush screen and a cyclone separator 46 connected downstream of the screening device 45.
  • the solids separated in the screening device 45 and the cyclone separator 46 are discharged at outlets 47 and 48 and can be fed to a further treatment.
  • the actual separation of the return water is provided by the separator 23 or 49 provided in the separation device, at the centrifugate outlet 50 of which the return water is obtained.
  • the concentrate separated from the treated sludge water in the separator 49 is introduced from the concentrate outlet 51 into a concentrate receiver 52, from where it passes via the concentrate return pump 35 into the concentrate return line 36 already described with reference to FIG. 2.
  • the nitrification / denitrification device 22 is designed as a pressure vessel.
  • the system pressure of up to 5 bar is applied through the air supply line 42.
  • a pressure maintaining device 53 provided in the outlet 50 of the separator 23 or 49 serves to maintain this system pressure.
  • Plate centrifuges in which conical jacket plates rotate, on which the solid components are conducted into the radially outer region of the plate centrifuge, have proven to be particularly suitable separators, while the lighter liquid components collect near the axis and are derived therefrom.
  • Nozzle separators have proven particularly useful, in which the separated solids, that is to say the concentrate, are discharged via nozzles distributed over the outer circumference and then flow off without pressure.
  • a separator type with a self-emptying drum is also possible, in which the separated concentrate accumulates in a concentrate space and periodically through an annular gap is carried out. The time interval and the duration of the discharge can be set individually according to the required degree of separation via a control device.
  • Another possible separator type is the nozzle separator.
  • both the centrate and the concentrate for the discharge are each conveyed by a rotating gripper. Furthermore, the concentrate is discharged via nozzles arranged at the bottom of the concentrate chamber. If the concentrate is too high, centrifugal valves on the periphery of the concentrate space also open due to the increased pressure and allow a further concentrate discharge. The degree of separation can be regulated particularly well by means of these measures.

Abstract

L'invention concerne un procédé et un dispositif d'épuration des eaux usées selon lequel on fait appel à un traitement par boue activée (5), suivi de la putréfaction (11) des boues résiduaires et de l'extraction des eaux boueuses (14, 15, 16) de la boue activée traitée. Selon ce procédé, on soumet les eaux boueuses extraites, avant de les ramener au traitement par boue activée, à un traitement par nitrification/dénitrification (22), puis on sépare l'eau de reflux par un séparateur (23), ce qui permet une importante élimination de l'azote.
EP97906151A 1996-03-14 1997-03-03 Procede et dispositif d'epuration des eaux usees Ceased EP0888256A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE19610074 1996-03-14
DE19610074 1996-03-14
PCT/EP1997/001040 WO1997033839A1 (fr) 1996-03-14 1997-03-03 Procede et dispositif d'epuration des eaux usees

Publications (1)

Publication Number Publication Date
EP0888256A1 true EP0888256A1 (fr) 1999-01-07

Family

ID=7788295

Family Applications (1)

Application Number Title Priority Date Filing Date
EP97906151A Ceased EP0888256A1 (fr) 1996-03-14 1997-03-03 Procede et dispositif d'epuration des eaux usees

Country Status (4)

Country Link
EP (1) EP0888256A1 (fr)
JP (1) JP2000506068A (fr)
AU (1) AU2094497A (fr)
WO (1) WO1997033839A1 (fr)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100319375B1 (ko) * 1999-07-30 2002-01-09 채문식 하수처리장 반류수의 질소제거방법 및 그 장치
DE102005040849A1 (de) * 2005-08-29 2007-03-01 Ingenieurgesellschaft für Wasser und Entsorgung mbH Verfahren und Vorrichtung zur Aufbereitung von verunreinigtem Abwasser, insbesondere zur Verwertung von Klärschlamm
DK2163524T4 (en) * 2008-09-12 2018-10-29 Demon Gmbh Process for treating ammonium-containing wastewater
ES2483150T3 (es) * 2010-03-10 2014-08-05 Demon Gmbh Procedimiento para la purificación biológica de un agua residual que contiene amonio

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2250446A1 (de) * 1971-10-23 1974-04-18 Rheinstahl Ag Verfahren zur aufbereitung von abwasserschlaemmen aus klaeranlagen und vorrichtung zu dessen durchfuehrung
FR2396724A1 (fr) * 1977-07-05 1979-02-02 Cgr Mev Procede de traitement des eaux et boues et dispositif pour la mise en oeuvre de ce procede
JP2796909B2 (ja) * 1992-07-27 1998-09-10 株式会社荏原総合研究所 廃水の処理方法
JP3368938B2 (ja) * 1993-05-11 2003-01-20 株式会社荏原製作所 汚水の処理方法及び装置

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9733839A1 *

Also Published As

Publication number Publication date
WO1997033839A1 (fr) 1997-09-18
JP2000506068A (ja) 2000-05-23
AU2094497A (en) 1997-10-01

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