EP1198422A1 - Method for treating sewage of a biological sewage treatment plant - Google Patents

Method for treating sewage of a biological sewage treatment plant

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Publication number
EP1198422A1
EP1198422A1 EP00969376A EP00969376A EP1198422A1 EP 1198422 A1 EP1198422 A1 EP 1198422A1 EP 00969376 A EP00969376 A EP 00969376A EP 00969376 A EP00969376 A EP 00969376A EP 1198422 A1 EP1198422 A1 EP 1198422A1
Authority
EP
European Patent Office
Prior art keywords
setpoint
oxygen
sewage
wastewater
content
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.)
Withdrawn
Application number
EP00969376A
Other languages
German (de)
French (fr)
Inventor
Joachim Hertrampf
Helmut Schrenk
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.)
Stadt Neustadt an der Weinstrasse
Air Liquide Deutschland GmbH
Original Assignee
STADT NEUSTADT AN DER WEINSTRA
Stadt Neustadt an der Weinstrasse
Messer Griesheim GmbH
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 STADT NEUSTADT AN DER WEINSTRA, Stadt Neustadt an der Weinstrasse, Messer Griesheim GmbH filed Critical STADT NEUSTADT AN DER WEINSTRA
Publication of EP1198422A1 publication Critical patent/EP1198422A1/en
Withdrawn legal-status Critical Current

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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
    • C02F3/30—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
    • C02F3/00—Biological treatment of water, waste water, or sewage
    • C02F3/006—Regulation methods for biological treatment
    • 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
    • C02F2209/14—NH3-N
    • 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
    • C02F2209/22—O2

Definitions

  • the invention relates to a method for treating wastewater from a biological sewage treatment plant, comprising a first treatment stage in which an oxygen-containing gas is supplied to the wastewater in a controlled manner as a function of a predetermined ⁇ 2 setpoint for the oxygen content in the wastewater, ammonium compounds contained in the wastewater being below Formation of nitrates are oxidized, and a second treatment stage in which the nitrates are removed from the waste water with the formation of gaseous nitrogen.
  • Oxygen is required for nitrification; specifically, 4.6 g 0 2 are required for the conversion of 1 g of NH 4 + ions. Oxygen is artificially added to the activated sludge to accelerate the process.
  • the oxygen content can be kept at a predetermined 0 2 setpoint and an adequate oxygen supply to the microorganisms can be guaranteed.
  • the level of the 0 2 setpoint depends on a large number of parameters, such as the type and extent of the dirt load to be expected, and can differ from wastewater treatment plant to wastewater treatment plant.
  • the oxygen content is usually kept at a 0 2 setpoint of approximately 2 mg / l (mg per liter of waste water).
  • the known method is very well suited for the elimination of nitrogen and it is characterized by high operational reliability.
  • Technical oxygen is usually used to supply the microorganisms with oxygen during the first treatment stage. This results in a significant part of the operating costs in the known treatment method.
  • the invention is therefore based on the object of reducing the oxygen requirement for wastewater purification and thus reducing the operating costs while maintaining a high level of operational reliability.
  • this object is achieved according to the invention by continuously measuring the ammonium content or a property of the waste water which can be correlated therewith, and by specifying the 0 2 setpoint as a function of the measured ammonium content.
  • the method according to the invention comprises a first and a second
  • the first control mechanism regulates the supply of oxygen to the wastewater as a function of a predetermined O 2 setpoint.
  • the controlled variable is therefore the oxygen content in the wastewater.
  • the 0 2 setpoint for the oxygen content in the waste water is regulated depending on the ammonium content in the waste water.
  • the controlled variable is the 0 2 setpoint. In the method according to the invention, this is therefore not a constant variable, but rather a variable which is predetermined by the ammonium content measured in the wastewater and is accordingly used in the first control mechanism.
  • the oxygen input into the wastewater can be adapted to the current need for nitrification. It has been shown that the rate of nitrification depends on the oxygen content of the waste water. Therefore, especially in low load times, for example during the night, the oxygen content in the wastewater can be easily reduced, with the proviso that the reduction takes place as a function of the ammonium content of the wastewater.
  • the O 2 setpoint is therefore not set constantly - as in the known method - but is set variably. This makes it possible to reduce the oxygen consumption for wastewater treatment without any noticeable impairment of the cleaning effect and accordingly to lower the operating costs.
  • the O 2 setpoint is specified depending on the ammonium content. To determine the ammonium content, this is either measured directly in the wastewater, or a property of the wastewater that can be correlated with the ammonium content is measured. In the latter case, the corresponding correlatable property of the waste water can also be used as the control variable for the 0 2 setpoint instead of the ammonium content.
  • the measurement can be carried out continuously or according to time intervals.
  • the wastewater to be treated passes through the first and second treatment stages at least once. It can also go through the treatment stages several times, for example in a circuit.
  • a lower limit of 0.5 mg / 1 is preferably specified for setting the O 2 setpoint. This specification serves to ensure the operational safety of the process, since the oxygen culture below this lower limit could impair the culture of the aerobic microorganisms and the effectiveness of wastewater treatment.
  • a value of 3 mg / 1 is preferably specified as the upper limit for the 0 setpoint.
  • the location of the measurement of the ammonium content or the property correlated therewith has an influence on the measured value and thus on the control behavior of the above-mentioned control mechanisms. For example, a measurement in the area before the first treatment stage - that is, before nitrification - will provide a different measured value for the ammonium content than a measurement in the area after the first or after the second treatment stage.
  • a measurement in the area before the first treatment stage - that is, before nitrification - will provide a different measured value for the ammonium content than a measurement in the area after the first or after the second treatment stage.
  • the ammonium content measured in this way is preferably kept at a nominal NH value in the range between 0.2 and 2.0 mg / l. If there is a deviation from the NH setpoint, the 0 2 setpoint is varied accordingly.
  • Figure 1 shows an embodiment of the method according to the invention in a schematic representation
  • Figure 2 is a measurement and control scheme for performing the method according to the invention.
  • FIG. 1 shows schematically a number of basins (1-4) of a sewage treatment plant, as are usually used for the microbial treatment of organically polluted municipal and industrial wastewater. It is a pre-clarifier
  • SPARE BLADE (RULE 26) 1, a denitrification tank 2, the actual activation tank 3 and one
  • Secondary clarifier 4 The inflow of the wastewater to be treated to the primary clarifier 1 is with the arrow 5 and the drain from the aeration tank 3 into the secondary clarifier
  • two so-called gassing mats 8 are mounted on the pool floor, via which technically pure oxygen is introduced into the waste water.
  • the gassing mats 8 are connected via an oxygen supply line 9 to an oxygen tank (not shown in FIG. 1).
  • the oxygen supply to the gassing mats 8 is controlled by means of a measuring and control device 10 as a function of a predetermined setpoint for the oxygen content in the wastewater of the activation tank 3.
  • an oxygen measuring probe 11 is immersed in the activated sludge.
  • the measured values determined by the oxygen measuring probe 11 are fed to the control device 10 via the line 12.
  • the ammonium content of the waste water is measured in the discharge 6 from the aeration tank 3 to the secondary clarifier 4.
  • an NH measuring device 13 is provided, which is also connected to the control device 10 via a line 14.
  • Submersible agitators 15 are provided in the denitrification basin 2 and in the aeration basin 3, which prevent activated sludge from settling.
  • the wastewater to be treated passes from the primary clarifier 1 and denitrification tank 2 into the activation tank 3, where the so-called nitrification takes place, in which ammonium compounds contained in the sewage water or in the activated sludge of the activation tank 3 are oxidized to nitrates by microorganisms.
  • technical oxygen is introduced into the activated sludge via the gassing mats 8.
  • the oxygen content of the activated sludge is continuously measured by means of the oxygen measuring probe 11 and by means of the control device 10 using a
  • SPARE BLADE (RULE 26) first control mechanism kept at a predetermined 0 2 setpoint.
  • the specification of the 0 2 setpoint lies in the range between 0.5 mg / 1 and 3 mg / 1.
  • the specification of the O 2 setpoint results from a second control mechanism, which is based on a measurement of the ammonium content in the wastewater.
  • the ammonium content is continuously measured in the area of the drain 6 and the measured values are fed to the control device 10.
  • the NH 4 setpoint for the ammonium content in the region of the discharge 6 is 1.0 mg / l (liter, based on waste water).
  • the 0 2 setpoint is lowered by means of the control device 10 as soon as the ammonium content falls below the preset NH setpoint and increases as soon as the ammonium content is above the preset NH 4 setpoint.
  • Aeration tank 4 and the associated withdrawal of the setpoint during low load periods oxygen savings of up to 30% can be achieved.
  • the control device 10 comprises a controller for the setting of the ammonium content in the outlet 6 of the aeration tank 3 (referred to as “NH controller”), an adjuster for the setting of the 0 2 content in the activation tank 3 (as the “O 2 setpoint value” Controller ”) and a controller for setting the 0 2 setpoint (referred to as” 0 2 setpoint controller ").
  • SPARE BLADE Values for the setpoint of the ammonium concentration in sequence 6 (referred to as “NH 4 setpoint”) and an upper and a lower limit for the O 2 setpoint are specified and stored in the control device 10.
  • the limit values for the O 2 - In the exemplary embodiment, the setpoint is 0.5 mg / l or 3 mg / l, and the NH setpoint is set to 1 mg / l.
  • the oxygen content of the waste water 4 (hereinafter referred to as “actual value of O 2 ”) is measured at regular intervals by means of the oxygen measurement probe 11.
  • the ammonium content of the waste water is also measured continuously determined in sequence 6 by means of the NH measuring device (hereinafter referred to as “NH actual value”) as soon as this.
  • the actual NH 4 value is fed to the control device 10 and compared with the target value by means of a processor.
  • the 0 2 setpoint for the oxygen control is reset, provided the 0 2 setpoint to be set is within the specified limit values.
  • This new setting of the 0 2 setpoint takes place in the ⁇ 2 setpoint adjuster.
  • the newly set O 2 setpoint is then used as the basis for the usual regulation of the oxygen content in the aeration tank by means of the 0 2 controller, ie in the event of a discrepancy between the actual O 2 value measured by means of the oxygen measuring probe 11 and the newly set 0 2 setpoint ( ⁇ O 2 # 0) the oxygen input via the gassing mats 8 is set accordingly.

Abstract

The invention relates to a method for decomposing nitrogen compounds contained in the sewage of a biological sewage treatment plant. The inventive method comprises a first treatment step during which a gas containing oxygen is fed in a controlled manner into the sewage according to a predetermined O2 specified value for the oxygen content in the sewage, whereby ammonium contained in the sewage is oxidized while resulting in the formation of nitrates. In addition, the inventive method comprises a second step during which the nitrates are eliminated while resulting in the formation of gaseous nitrogen. Based on this fact and while maintaining a high level of operational reliability, the aim of the invention is to reduce the oxygen demand and thus the operational costs. To this end, the invention provides that the ammonium content or a property of the sewage that can be correlated therewith is continuously measured, and the O2 specified value is preset according to the measured ammonium content.

Description

Verfahren zur Behandlung von Abwasser einer biologischen Kläranlage Process for treating wastewater from a biological sewage treatment plant
Die Erfindung betrifft ein Verfahren zur Behandlung von Abwasser einer biologischen Kläranlage, umfassend eine erste Behandlungsstufe, bei der dem Abwasser ein sauerstoffhaltiges Gas in Abhängigkeit eines vorgegebenen θ2-Sollwertes für den Sauerstoffgehalt im Abwasser geregelt zugeführt wird, wobei im Abwasser enthaltende Ammonium-Verbindungen unter Bildung von Nitraten oxidiert werden, und eine zweite Behandlungsstufe, bei der die Nitrate unter Bildung von gasförmigem Stickstoff aus dem Abwasser entfernt werden.The invention relates to a method for treating wastewater from a biological sewage treatment plant, comprising a first treatment stage in which an oxygen-containing gas is supplied to the wastewater in a controlled manner as a function of a predetermined θ 2 setpoint for the oxygen content in the wastewater, ammonium compounds contained in the wastewater being below Formation of nitrates are oxidized, and a second treatment stage in which the nitrates are removed from the waste water with the formation of gaseous nitrogen.
Im Rahmen der Reinigung kommunaler und industrieller Abwässer ist unter anderem auch eine weitgehende Eliminierung von Stickstoffverbindungen erforderlich. Ein dafür geeignetes Verfahren ist unter der Bezeichnung „Biox-N-Verfahren" in der Produktinformationsschrift „Gas aktuell 48, Berichte aus Forschung und Technik" der Messer Griesheim GmbH (Ausgabe 9124/VII; 1994) beschrieben. Bei diesem Verfahren werden die im Belebtschlamm von Kläranlagen enthaltenen Stickstoffverbindungen in zwei Behandlungsschritten abgebaut. Im ersten Schritt - als Nitrifikation bezeichnet - werden Ammonium (NH +)-haltige Verbindungen durch spezielle aerobe Mikroorganismen (sogenannte „Nitrifizierer") zu Nitraten oxidiert. Dieser Behandlungsschritt läßt sich schematisch anhand folgender Reaktionsgleichungen beschreiben:As part of the treatment of municipal and industrial wastewater, extensive elimination of nitrogen compounds is also required. A suitable process is described under the name "Biox-N process" in the product information brochure "Gas Aktuell 48, Reports from Research and Technology" of Messer Griesheim GmbH (edition 9124 / VII; 1994). In this process, the nitrogen compounds contained in the activated sludge from sewage treatment plants are broken down in two treatment steps. In the first step - called nitrification - compounds containing ammonium (NH + ) are oxidized to nitrates by special aerobic microorganisms (so-called "nitrifiers"). This treatment step can be described schematically using the following reaction equations:
2 NH4 + + 3 02 ■ 2 N02 "+ 4 H+ + 2 H2O 2 NO2 " + 02 -» 2 N03 " 2 NH 4 + + 3 0 2 ■ 2 N0 2 " + 4 H + + 2 H 2 O 2 NO 2 " + 0 2 - »2 N0 3 "
Für die Nitrifikation ist Sauerstoff erforderlich; konkret werden für die Umsetzung von 1 g NH4 +- Ionen 4,6 g 02 benötigt. Zur Beschleunigung des Vorganges wird dem Belebtschlamm Sauerstoff künstlich zugeführt. Durch eine geeignete Regelung kann der Sauerstoffgehalt auf einem vorgegebenen 02-Sollwert gehalten und eine ausreichende Sauerstoffversorgung der Mikroorganismen gewährleistet werden. Die Höhe des 02-Sollwertes hängt von einer Vielzahl von Parametern, wie beispielsweise Art und Umfang der zu erwartenden Schmutzfracht ab und kann sich von Kläranlage zu Kläranlage unterscheiden. Üblicherweise wird der Sauerstoffgehalt bei einem 02- Sollwert von etwa 2 mg/l (mg pro Liter Abwasser) gehalten.Oxygen is required for nitrification; specifically, 4.6 g 0 2 are required for the conversion of 1 g of NH 4 + ions. Oxygen is artificially added to the activated sludge to accelerate the process. By means of a suitable regulation, the oxygen content can be kept at a predetermined 0 2 setpoint and an adequate oxygen supply to the microorganisms can be guaranteed. The level of the 0 2 setpoint depends on a large number of parameters, such as the type and extent of the dirt load to be expected, and can differ from wastewater treatment plant to wastewater treatment plant. The oxygen content is usually kept at a 0 2 setpoint of approximately 2 mg / l (mg per liter of waste water).
ERSATZBLÄTT (REGEL 26) Der zweite Behandlungsschritt wird als „Denitrifikation" bezeichnet. Dabei nutzen die herkömmlichen kohlenstoffabbauenden Bakterien unter anaeroben Bedingungen das im Abwasser vorhandene Nitrat als Sauerstoffquelle. Der verbleibende gasförmige Stickstoff entweicht in die Atmosphäre. Die „Denitrifikation" läßt sich anhand folgender chemischer Gleichung beschreiben:SPARE BLADE (RULE 26) The second treatment step is called "denitrification". The conventional carbon-degrading bacteria use the nitrate present in the wastewater as an oxygen source under anaerobic conditions. The remaining gaseous nitrogen escapes into the atmosphere. "Denitrification" can be described using the following chemical equation:
2 NO3 ' + 10 H - N2t + 2 OH" + 4 H2O2 NO 3 ' + 10 H - N 2 t + 2 OH " + 4 H 2 O
Das bekannte Verfahren ist für die Eliminierung von Stickstoff sehr gut geeignet und es zeichnet sich durch hohe Betriebssicherheit aus. Für die Sauerstoffversorgung der Mikroorganismen während der ersten Behandlungsstufe wird üblicherweise technischer Sauerstoff verwendet. Daraus ergibt sich ein wesentlicher Teil der Betriebskosten bei dem bekannten Behandlungsverfahren.The known method is very well suited for the elimination of nitrogen and it is characterized by high operational reliability. Technical oxygen is usually used to supply the microorganisms with oxygen during the first treatment stage. This results in a significant part of the operating costs in the known treatment method.
Der Erfindung liegt daher die Aufgabe zugrunde, bei gleichbleibend hoher Betriebssicherheit den Sauerstoffbedarf bei der Abwasserreinigung zu verringern und damit die Betriebskosten zu senken.The invention is therefore based on the object of reducing the oxygen requirement for wastewater purification and thus reducing the operating costs while maintaining a high level of operational reliability.
Diese Aufgabe wird ausgehend vom eingangs genannten Verfahren erfindungsgemäß dadurch gelöst, daß der Ammonium-Gehalt oder eine damit korrelierbare Eigenschaft des Abwassers fortlaufend gemessen, und der 02-Sollwert in Abhängigkeit vom gemessenen Ammonium-Gehalt vorgegeben wird.Starting from the method mentioned at the outset, this object is achieved according to the invention by continuously measuring the ammonium content or a property of the waste water which can be correlated therewith, and by specifying the 0 2 setpoint as a function of the measured ammonium content.
Das erfindungsgemäße Verfahren umfaßt einen ersten und einen zweitenThe method according to the invention comprises a first and a second
Regelmechanismus. Durch den ersten Regelmechanismus wird die Zufuhr von Sauerstoff zum Abwasser in Abhängigkeit von einem vorgegebenen O2-Sollwert geregelt. Regelgröße ist demnach der Sauerstoffgehalt im Abwasser. Beim zweiten Regelmechanismus wird der 02-Sollwert für den Sauerstoffgehalt im Abwasser in Abhängigkeit vom Ammonium-Gehalt des Abwassers geregelt. Regelgröße ist hierbei der 02-Sollwert. Dieser ist beim erfindungsgemäßen Verfahren somit keine konstante Größe, sondern eine Variable, die durch den im Abwasser gemessenen Ammonium-Gehalt vorgegeben und dementsprechend im Rahmen des ersten Regelmechanismus verwendet wird.Control mechanism. The first control mechanism regulates the supply of oxygen to the wastewater as a function of a predetermined O 2 setpoint. The controlled variable is therefore the oxygen content in the wastewater. In the second control mechanism, the 0 2 setpoint for the oxygen content in the waste water is regulated depending on the ammonium content in the waste water. The controlled variable is the 0 2 setpoint. In the method according to the invention, this is therefore not a constant variable, but rather a variable which is predetermined by the ammonium content measured in the wastewater and is accordingly used in the first control mechanism.
ERSATZBLÄTT (REGEL 26) Mit dieser Verfahrensweise läßt sich der Sauerstoffeintrag in das Abwasser dem aktuellen Bedarf für die Nitrifikation anpassen. Es hat sich gezeigt, daß die Nitrifikationsgeschwindigkiet vom Sauerstoffgehalt des Abwassers abhängt. Daher kann insbesondere in Schwachlastzeiten, beispielsweise während der Nacht, der Sauerstoffgehalt im Abwasser ohne weiteres abgesenkt werden, mit der Maßgabe, daß die Absenkung in Abhängigkeit vom Ammonium-Gehalt des Abwassers erfolgt. Je geringer der Ammonium-Gehalt des Abwassers ist, umso niedriger kann der Sauerstoffgehalt - und damit einhergehend, der O2-Sollwert eingestellt werden. Erfindungsgemäß wird daher der O2-Sollwert nicht konstant - wie bei dem bekannten Verfahren - sondern variabel vorgegeben. Dadurch ist es möglich, den Sauerstoffverbrauch für die Abwassereinigung ohne erkennbare Beeinträchtigung der Reinigungswirkung zu verringern und dementsprechend die Betriebskosten zu senken.SPARE BLADE (RULE 26) With this procedure, the oxygen input into the wastewater can be adapted to the current need for nitrification. It has been shown that the rate of nitrification depends on the oxygen content of the waste water. Therefore, especially in low load times, for example during the night, the oxygen content in the wastewater can be easily reduced, with the proviso that the reduction takes place as a function of the ammonium content of the wastewater. The lower the ammonium content of the wastewater, the lower the oxygen content - and with it, the O 2 setpoint. According to the invention, the O 2 setpoint is therefore not set constantly - as in the known method - but is set variably. This makes it possible to reduce the oxygen consumption for wastewater treatment without any noticeable impairment of the cleaning effect and accordingly to lower the operating costs.
Der O2-Sollwert wird in Abhängigkeit vom Ammonium-Gehalt vorgegeben. Zur Ermittlung des Ammonium-Gehalt wird dieser entweder unmittelbar im Abwasser gemessen, oder es wird eine mit dem Ammonium-Gehalt korrelierbare Eigenschaft des Abwassers gemessen. Im letztgenannten Fall kann beim Regelmechanismus für den 02-Sollwert als Stellgröße anstelle des Ammonium-Gehaltes auch die entsprechende korrelierbare Eigenschaft des Abwassers verwendet werden. Die Messung kann kontinuierlich oder nach Zeitintervallen erfolgen.The O 2 setpoint is specified depending on the ammonium content. To determine the ammonium content, this is either measured directly in the wastewater, or a property of the wastewater that can be correlated with the ammonium content is measured. In the latter case, the corresponding correlatable property of the waste water can also be used as the control variable for the 0 2 setpoint instead of the ammonium content. The measurement can be carried out continuously or according to time intervals.
Das zu behandelnde Abwasser durchläuft die erste und die zweite Behandlungsstufe mindestens einmal. Es kann die Behandlungsstufen auch mehrfach, beispielsweise im Kreislauf, durchlaufen.The wastewater to be treated passes through the first and second treatment stages at least once. It can also go through the treatment stages several times, for example in a circuit.
Vorzugsweise wird für die Einstellung des O2-Sollwertes eine Untergrenze von 0,5 mg/1 vorgegeben. Diese Vorgabe dient der Betriebssicherheit des Verfahrens, da bei Sauerstoffgehalten unterhalb dieser Untergrenze die Kultur der aeroben Mikroorganismen und die Effektivität der Abwasserreinigung beeinträchtigt werden könnte.A lower limit of 0.5 mg / 1 is preferably specified for setting the O 2 setpoint. This specification serves to ensure the operational safety of the process, since the oxygen culture below this lower limit could impair the culture of the aerobic microorganisms and the effectiveness of wastewater treatment.
Als Obergrenze für den 0 -Sollwert wird bevorzugt ein Wert von 3 mg/1 vorgegeben. Zwar kann der optimale Sauerstoffgehalt m Hinblick auf die Effektivität derA value of 3 mg / 1 is preferably specified as the upper limit for the 0 setpoint. Although the optimal oxygen content can with regard to the effectiveness of the
ERSATZBLÄTT (REGEL 26) Abwasserreinigung auch über diesem Wert liegen Die angegebene Obergrenze dient jedoch der Senkung der Betriebskosten, wenn die Kosten für die Aufrechterhaltung eines höheren Sauerstoffgehaltes nicht mehr durch eine entsprechende Verbesserung der Abwasserreinigung gerechtfertigt sind.SPARE BLADE (RULE 26) Wastewater treatment is also above this value. However, the specified upper limit serves to reduce operating costs if the costs for maintaining a higher oxygen content are no longer justified by a corresponding improvement in wastewater treatment.
Der Ort der Messung des Ammonium-Gehaltes oder der damit korrelierbaren Eigenschaft hat Einfluß auf den Meßwert und damit auf das Regelverhalten der oben genannten Regelmechanismen. Beispielsweise wird eine Messung im Bereich vor der ersten Behandlungsstufe - also vor der Nitrifikation - einen anderen Meßwert für den Ammonium-Gehalt liefern als eine Messung im Bereich nach der ersten oder nach der zweiten Behandlungsstufe. Im Hinblick auf eine hohe Betriebssicherheit hat es sich als vorteilhaft erwiesen, den Ammonium-Gehalt im Abwasser zu ermitteln, nachdem es mindestens einmal die erste Behandlungsstufe durchlaufen hat. Dadurch werden Schwankungen des Ammonium-Gehaltes, wie sie beispielsweise im Bereich des Einlaufes von unbehandeltem Abwasser in ein Klärbecken beobachtet werden, abgepuffert. In der Praxis hat sich die Messung des Ammonium-Gehalt im Ablauf des Abwassers in ein nachgeschaltetes Nachklärbecken bewährt.The location of the measurement of the ammonium content or the property correlated therewith has an influence on the measured value and thus on the control behavior of the above-mentioned control mechanisms. For example, a measurement in the area before the first treatment stage - that is, before nitrification - will provide a different measured value for the ammonium content than a measurement in the area after the first or after the second treatment stage. With a view to a high level of operational safety, it has proven to be advantageous to determine the ammonium content in the waste water after it has undergone the first treatment stage at least once. As a result, fluctuations in the ammonium content, such as those observed in the area where untreated waste water enters a clarifier, are buffered. In practice, the measurement of the ammonium content in the effluent in a downstream clarifier has proven itself.
Der so gemessene Ammonium-Gehalt wird bevorzugt auf einem NH -Sollwert im Bereich zwischen 0,2 und 2,0 mg/1 gehalten. Bei einer Abweichung vom NH -Sollwert wird der 02-Sollwert entsprechend variiert.The ammonium content measured in this way is preferably kept at a nominal NH value in the range between 0.2 and 2.0 mg / l. If there is a deviation from the NH setpoint, the 0 2 setpoint is varied accordingly.
Nachfolgend wird die Erfindung anhand eines Ausführungsbeispiels und einer Zeichnung näher erläutert. In der Zeichnung zeigen im einzelnenThe invention is explained in more detail below using an exemplary embodiment and a drawing. In the drawing show in detail
Figur 1 eine Ausführungsform des erfindungsgemäßen Verfahrens in schematischer Darstellung, undFigure 1 shows an embodiment of the method according to the invention in a schematic representation, and
Figur 2 ein Meß- und Regelschema für die Durchführung des erfindungsgemäßen Verfahren.Figure 2 is a measurement and control scheme for performing the method according to the invention.
In Figur 1 sind schematisch mehrere Becken (1 - 4) einer Kläranlage dargestellt, wie sie üblicherweise zur mikrobiellen Behandlung organisch belasteter kommunaler und industrieller Abwässer eingesetzt werden. Dabei handelt es sich um ein VorklärbeckenFIG. 1 shows schematically a number of basins (1-4) of a sewage treatment plant, as are usually used for the microbial treatment of organically polluted municipal and industrial wastewater. It is a pre-clarifier
ERSATZBLÄTT (REGEL 26) 1 , ein Denitrifikationsbecken 2, das eigentliche Belebungsbecken 3 und einSPARE BLADE (RULE 26) 1, a denitrification tank 2, the actual activation tank 3 and one
Nachklärbecken 4. Der Zulauf des zu behandelnden Abwassers zum Vorklärbecken 1 ist mit dem Pfeil 5 und der Ablauf aus dem Belebungsbecken 3 in das NachklärbeckenSecondary clarifier 4. The inflow of the wastewater to be treated to the primary clarifier 1 is with the arrow 5 and the drain from the aeration tank 3 into the secondary clarifier
4 mit dem Pfeil 6 symbolisiert. Im übrigen wird die Fließbewegung des Abwassers durch die verschiedenen Becken (1 - 4) während der Behandlung durch die4 symbolized by arrow 6. In addition, the flow of waste water through the various pools (1 - 4) during treatment by the
Richtungspfeile 7 angedeutet.Directional arrows 7 indicated.
Zur Belüftung des Belebtschlamms im Belebungsbecken 3 sind am Beckenboden zwei sogenannte Begasungsmatten 8 montiert, über die technisch reiner Sauerstoff in das Abwasser eingebracht wird. Hierzu sind die Begasungsmatten 8 über eine Sauerstoff- Zufuhrleitung 9 mit einem (in Figur 1 nicht dargestellten) Sauerstofftank verbunden. Die Sauerstoffzufuhr zu den Begasungsmatten 8 wird mittels einer Meß- und Regeleinrichtung 10 in Abhängigkeit von einem vorgegebenen Sollwert für den Sauerstoffgehalt im Abwasser des Belebungsbeckens 3 geregelt. Zur Messung des Sauerstoffgehaltes taucht eine Sauerstoff-Meßsonde 11 in den Belebtschlamm ein.To aerate the activated sludge in the aeration tank 3, two so-called gassing mats 8 are mounted on the pool floor, via which technically pure oxygen is introduced into the waste water. For this purpose, the gassing mats 8 are connected via an oxygen supply line 9 to an oxygen tank (not shown in FIG. 1). The oxygen supply to the gassing mats 8 is controlled by means of a measuring and control device 10 as a function of a predetermined setpoint for the oxygen content in the wastewater of the activation tank 3. To measure the oxygen content, an oxygen measuring probe 11 is immersed in the activated sludge.
Die von der Sauerstoff-Meßsonde 11 ermittelten Meßwerte werden über die Leitung 12 der Regeleinrichtung 10 zugeführt.The measured values determined by the oxygen measuring probe 11 are fed to the control device 10 via the line 12.
Im Ablauf 6 vom Belebungsbecken 3 zum Nachklärbecken 4 wird der Ammonium- Gehalt des Abwassers gemessen. Hierzu ist eine NH -Meßeinrichtung 13vorgesehen, die ebenfalls über eine Leitung 14 mit der Regeleinrichtung 10 verbunden ist.The ammonium content of the waste water is measured in the discharge 6 from the aeration tank 3 to the secondary clarifier 4. For this purpose, an NH measuring device 13 is provided, which is also connected to the control device 10 via a line 14.
Im Denitrifikationsbecken 2 und im Belebungsbecken 3 sind jeweils Tauchmotorrührwerke 15 vorgesehen, die ein Absetzten von Belebtschlamm verhindern.Submersible agitators 15 are provided in the denitrification basin 2 and in the aeration basin 3, which prevent activated sludge from settling.
Vom Vorklärbecken 1 und Denitrifikationsbecken 2 gelangt das zu behandelnde Abwasser in das Belebungsbecken 3. Dort findet die sogenannte Nitrifikation statt, bei der im Abwasser bzw. im Belebtschlamm des Belebungsbeckens 3 enthaltene Ammoniumverbindungen durch Mikroorganismen zu Nitraten oxidiert werden. Hierzu wird technischer Sauerstoff über die Begasungsmatten 8 in den Belebtschlamm eingetragen. Der Sauerstoffgehalt des Belebtschlamms wird fortlaufend mittels der Sauerstoffmeß-Sonde 11 gemessen und mittels der Regeleinrichtung 10 anhand einesThe wastewater to be treated passes from the primary clarifier 1 and denitrification tank 2 into the activation tank 3, where the so-called nitrification takes place, in which ammonium compounds contained in the sewage water or in the activated sludge of the activation tank 3 are oxidized to nitrates by microorganisms. For this purpose, technical oxygen is introduced into the activated sludge via the gassing mats 8. The oxygen content of the activated sludge is continuously measured by means of the oxygen measuring probe 11 and by means of the control device 10 using a
ERSATZBLÄTT (REGEL 26) ersten Regelmechanismus auf einem vorgegebenen 02-Sollwert gehalten. Die Vorgabe des 02-Sollwertes liegt im Bereich zwischen 0,5 mg/1 und 3 mg/1.SPARE BLADE (RULE 26) first control mechanism kept at a predetermined 0 2 setpoint. The specification of the 0 2 setpoint lies in the range between 0.5 mg / 1 and 3 mg / 1.
Die Vorgabe des O2-Sollwertes ergibt sich durch einen zweiten Regelmechanismus, der auf einer Messung des Ammonium-Gehaltes im Abwassers beruht. Hierzu wird der Ammonium-Gehalt im Bereich des Ablaufes 6 fortlaufend gemessen und die Meßwerte der Regeleinrichtung 10 zugeführt. Der NH4-Sollwert für den Ammonium-Gehalt im Bereich des Ablaufes 6 beträgt im Ausführungsbeispiel 1 ,0 mg/l (Liter, bezogen auf Abwasser). Mittels der Regeleinrichtung 10 wird der 02-Sollwertes gesenkt, sobald der Ammonium-Gehalt unter den voreingestellten NH -Sollwert fällt und erhöht, sobald der Ammonium-Gehalt über dem voreingestellten NH4-Sollwert liegt.The specification of the O 2 setpoint results from a second control mechanism, which is based on a measurement of the ammonium content in the wastewater. For this purpose, the ammonium content is continuously measured in the area of the drain 6 and the measured values are fed to the control device 10. In the exemplary embodiment, the NH 4 setpoint for the ammonium content in the region of the discharge 6 is 1.0 mg / l (liter, based on waste water). The 0 2 setpoint is lowered by means of the control device 10 as soon as the ammonium content falls below the preset NH setpoint and increases as soon as the ammonium content is above the preset NH 4 setpoint.
Über einen Wasser-Kreislauf 17 wird stark nitrathaltiges Wasser in das Denitrifikationsbecken 2 zurückgeleitet. Außerdem wird aus dem Nachklärbecken 4 Schlamm abgezogen und ein Teil davon als Rücklaufschlamm über dieHighly nitrate-containing water is returned to the denitrification basin 2 via a water circuit 17. In addition, 4 sludge is withdrawn from the secondary clarifier and part of it as return sludge via the
Rückschlammleitung 16 in das Denitrifikationsbecken 2 geführt. Unter den dort herrschenden anoxischen Bedingungen dienen die Nitrate den Mikroorganismen als Sauerstoffquelle. Der verbleibende gasförmige Stickstoff entweicht in die Atmosphäre.Back sludge line 16 led into the denitrification tank 2. Under the anoxic conditions prevailing there, the nitrates serve as a source of oxygen for the microorganisms. The remaining gaseous nitrogen escapes into the atmosphere.
In der Praxis konnte durch diese variable Vorgabe des O2-Sollwertes imIn practice, this variable specification of the O 2 setpoint in the
Belebungsbecken 4 und die damit einhergehende Zurücknahme des Sollwertes in Schwachlastzeiten eine Einsparung an Sauerstoff bis zu 30 % erzielt werden.Aeration tank 4 and the associated withdrawal of the setpoint during low load periods, oxygen savings of up to 30% can be achieved.
Nachfolgend wird das erfindungsgemäße Verfahren anhand dem Meß- und Regelschema gemäß Figur 2 näher erläutert. Die in Figur 2 genannten Bezugsziffern beziehen sich auf die Bauteile der in Figur 1 dargestellten Vorrichtung.The method according to the invention is explained in more detail below on the basis of the measurement and control scheme according to FIG. The reference numerals given in FIG. 2 refer to the components of the device shown in FIG. 1.
Die Regeleinrichtung 10 umfaßt einen Regler für die Einstellung des Ammonium- Gehaltes im Ablauf 6 des Belebunsgbeckens 3 (als „NH -Regler" bezeichnet), einen Einsteller für die Einstellung des 02-Gehaltes im Belebungsbecken 3 (als „O2-Sollwert- Steller" bezeichnet) und einen Regler für die Einstellung des 02-Sollwertes (als „02- Sollwert -Regler" bezeichnet).The control device 10 comprises a controller for the setting of the ammonium content in the outlet 6 of the aeration tank 3 (referred to as “NH controller”), an adjuster for the setting of the 0 2 content in the activation tank 3 (as the “O 2 setpoint value” Controller ") and a controller for setting the 0 2 setpoint (referred to as" 0 2 setpoint controller ").
ERSATZBLÄTT (REGEL 26) In der Regeleinrichtung 10 werden Werte für den Sollwert der Ammonium- Konzentration im Ablauf 6 (als „NH4-Sollwert" bezeichnet) und ein oberer und ein unterer Grenzwert für den O2-Sollwert vorgegeben und gespeichert. Die Grenzwerte für den O2-Sollwert liegen im Ausführungsbeispiel bei 0,5 mg/l bzw. bei 3 mg/l und der NH -Sollwert wird auf 1 mg/l eingestellt.SPARE BLADE (RULE 26) Values for the setpoint of the ammonium concentration in sequence 6 (referred to as “NH 4 setpoint”) and an upper and a lower limit for the O 2 setpoint are specified and stored in the control device 10. The limit values for the O 2 - In the exemplary embodiment, the setpoint is 0.5 mg / l or 3 mg / l, and the NH setpoint is set to 1 mg / l.
Wie aus dem in Figur 2 dargestellten Meß- und Regelschema ersichtlich, wird mittels der Sauerstoff-Meßsonde 11 der Sauerstoffgehalt des Abwassers 4 (im folgenden als „O2-lstwert" bezeichnet) nach regelmäßigen Zeitintervallen gemessen. Ebenso wird der Ammonium-Gehalt des Abwassers im Ablauf 6 mittels der NH -Meßeinrichtung fortlaufend ermittelt (im folgenden als „NH -Istwert" bezeichnet), sobald dieses . Der NH4-Istwert wird der Regeleinrichtung 10 zugeführt und mittels eines Prozessors mit dem Sollwert verglichen.As can be seen from the measurement and control diagram shown in FIG. 2, the oxygen content of the waste water 4 (hereinafter referred to as “actual value of O 2 ”) is measured at regular intervals by means of the oxygen measurement probe 11. The ammonium content of the waste water is also measured continuously determined in sequence 6 by means of the NH measuring device (hereinafter referred to as “NH actual value”) as soon as this. The actual NH 4 value is fed to the control device 10 and compared with the target value by means of a processor.
Bei einer Abweichung zwischen dem NH4-Istwert und dem NH4-Sollwert (ΔNH # 0) wird der 02-Sollwert für die Sauerstoffregelung neu eingestellt, sofern der einzustellende 02-Sollwert innerhalb der vorgegebenen Grenzwerte liegt. Diese Neu- Einstellung des 02-Sollwertes erfolgt im θ2-Sollwert-Steller. Der neu eingestellte O2- Sollwert wird dann der üblichen Regelung des Sauerstoffgehaltes im Belebungsbecken mittels des 02-Reglers zugrundegelegt, d.h., bei einer Abweichung zwischen dem mittels der Sauerstoffmeß-Sonde 11 gemessenen O2-lstwert und dem neu eingestellten 02-Sollwert (ΔO2 # 0) wird der Sauerstoffeintrag über die Begasungsmatten 8 entsprechend eingestellt.If there is a discrepancy between the actual NH 4 value and the NH 4 setpoint (ΔNH # 0), the 0 2 setpoint for the oxygen control is reset, provided the 0 2 setpoint to be set is within the specified limit values. This new setting of the 0 2 setpoint takes place in the θ 2 setpoint adjuster. The newly set O 2 setpoint is then used as the basis for the usual regulation of the oxygen content in the aeration tank by means of the 0 2 controller, ie in the event of a discrepancy between the actual O 2 value measured by means of the oxygen measuring probe 11 and the newly set 0 2 setpoint (ΔO 2 # 0) the oxygen input via the gassing mats 8 is set accordingly.
ERSATZBL TT (REGEL 26) ERSATZBL TT (RULE 26)

Claims

Patentansprüche claims
1. Verfahren zum Abbau von Stickstoff-Verbindungen im Abwasser einer biologischen Kläranlage, umfassend eine erste Behandlungsstufe, bei der dem1. A process for the degradation of nitrogen compounds in the wastewater of a biological sewage treatment plant, comprising a first treatment stage in which the
Abwasser ein sauerstoffhaltiges Gas in Abhängigkeit eines vorgegebenen O2- Sollwertes für den Sauerstoffgehalt im Abwasser geregelt zugeführt wird, wobei im Abwasser enthaltende Ammonium unter Bildung von Nitraten oxidiert werden, und eine zweite Behandlungsstufe, bei der die Nitrate unter Bildung von gasförmigem Stickstoff eliminiert werden, dadurch gekennzeichnet, daß der Ammonium-Gehalt oder eine damit korrelierbare Eigenschaft des Abwassers fortlaufend gemessen, und der 02-Sollwert in Abhängigkeit vom gemessenen Ammonium-Gehalt vorgegeben wird.An oxygen-containing gas is supplied to wastewater in a controlled manner as a function of a predetermined O 2 setpoint for the oxygen content in the wastewater, wherein ammonium contained in the wastewater is oxidized to form nitrates, and a second treatment step in which the nitrates are eliminated to form gaseous nitrogen. characterized in that the ammonium content or a property of the waste water which can be correlated therewith is measured continuously, and the 0 2 setpoint is predetermined as a function of the measured ammonium content.
2. Verfahren nach Anspruch 1 , dadurch gekennzeichnet, daß für die Untergrenze für den O2-Sollwert ein Wert von 0,5 mg/l vorgegeben wird.2. The method according to claim 1, characterized in that a value of 0.5 mg / l is specified for the lower limit for the O 2 setpoint.
3. Verfahren nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß als Obergrenze für den 02-Sollwert ein Wert von 3 mg/l vorgegeben wird.3. The method according to claim 1 or 2, characterized in that a value of 3 mg / l is specified as the upper limit for the 0 2 setpoint.
4. Verfahren nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, daß der Ammonium-Gehalt im Abwassers gemessen wird, nachdem es mindestens einmal die erste Behandlungsstufe durchlaufen hat.4. The method according to any one of claims 1 to 3, characterized in that the ammonium content in the waste water is measured after it has passed through the first treatment stage at least once.
5. Verfahren nach Anspruch 4, dadurch gekennzeichnet, daß der5. The method according to claim 4, characterized in that the
Ammonium-Gehalt auf einem NH -Sollwert im Bereich zwischen 0,2 und 2,0 mg/l gehalten wird.Ammonium content is kept at a NH setpoint in the range between 0.2 and 2.0 mg / l.
ERSATZBL TT (REGEL 26) ERSATZBL TT (RULE 26)
EP00969376A 1999-10-07 2000-09-30 Method for treating sewage of a biological sewage treatment plant Withdrawn EP1198422A1 (en)

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FR2685692B1 (en) * 1991-12-31 1997-03-28 Omnium Traitement Valorisa PROCESS FOR THE PURIFICATION OF INDUSTRIAL AND / OR URBAN EFFLUENTS OF THE ACTIVE SLUDGE TYPE.
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