GERMAN ATV-DVWK RULES AND STANDARDS
Advisory Leaflet ATV-DVWK-M 265E Regulation of Oxygen Transfer with the Activated Sludge Process March 2000
- ABSTRACT English version in preparation
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ATV-DVWK-M 265E
Contents Preparation ............................................................................................................................................ User Notes ............................................................................................................................................. Foreword................................................................................................................................................
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1
3
Area of Application ...............................................................................................................
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Basic elements .......................................................................................................
2.1 2.2
Process technology.................................................................................................. Control engineering..................................................................................................
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Dimensioning and design of aeration systems ..................................................
4
Surface aeration .....................................................................................................
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Pressure aeration...................................................................................................
5.1 5.2 5.2.1 5.2.2 5.2.3
General .................................................................................................................... Regulation ................................................................................................................ Single-cycle regulation ............................................................................................. Constant pressure regulation................................................................................... Cascade regulation with independent sequential circuit..........................................
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Notes on energy saving and on the concept ......................................................
6.1 6.2 6.3 6.4 6.5
Optimisation of energy consumption........................................................................ Measuring point for O2 measurement electrodes .................................................... Design value ............................................................................................................ Substitutional value strategies ................................................................................. Examination of the economic efficiency with the concept
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Summary of standard specifications and standards
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March 2000
English version in preparation
ATV-DVWK-M 265E
Foreword A revision of the Guide ATV-H 265 (1991) ”Regulation of the Oxygen Transfer with the Activated Sludge Process” has become necessary due to the technical development which has taken place in the meanwhile, and the operating experience gained since that date. In particular there were further developments with frequency regulated motors, with roller aeration for deep tanks and diffused air aeration membranes. Through the increased installation of flexible aeration zones, constant pressure regulation has gained in significance. In addition, economical factors have been taken into account with the revision.
1
Area of Application
With the activated sludge process sufficient oxygen concentration is a prerequisite for effective treatment of wastewater. Furthermore, the oxygen requirement is subject to variations in a biological stage due to changes to the loading, the temperature, the concentration of the activated sludge and other parameters. The facilities for the transfer of oxygen must therefore be so designed that, on one hand, demand peaks can be covered and, on the other hand, the plant is not fed too much oxygen with lower loading.
The necessary energy for the oxygen transfer amounts to up to two thirds of the total requirement of a wastewater treatment plant. For this, the controlled operation of the aeration units is to enable a reduction of the energy required for the oxygen transfer. In addition, too high O2 concentrations which, as a rule, disrupt the processes of biological phosphate removal and denitrification can be prevented through regulation. Depending on the selected process technology for the removal of carbon, nitrogen and phosphorus, various regulation strategies are recommended, which are described comprehensively for nitrogen removal in Advisory Leaflet ATV-M 268E (2). This Advisory Leaflet is based on this and deals with the adoption of the appropriate controls and regulation for oxygen transfer. Information on the dimensioning of plants for mainly municipal wastewater is, inter alia, to be found in Standard ATV-A 131E [1]. Objective of this Advisory Leaflet is to give the user assistance with the selection of a suitable regulation concept for oxygen transfer and information on the mechanical engineering equipment with the activated sludge process. The area of application of this Advisory Leaflet is limited to the activated sludge process and to aeration using tmospheric oxygen.
March 2000
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