General Sewage Technology

Two-stage denitrification of filtrates/centrates from sludge dewatering

It has been demonstrated that the chemostat process investigated, which comprises nitrification and a downstream denitrification stage, can be successfully and cost-effectively implemented on an industrial scale. On the basis of simulation calculations completed, the improvement of discharge values is anticipated by the reduction of the nitrogen load and the attenuation of the influent peak load.

 

Summary

The recirculation of centrates/filtrates from sludge dewatering in the influent of municipal sewage treatment plants is associated with repollution by nitrogen compounds which accounts for 10 – 30% of the influent nitrogen load, thereby leading to operating problems.  One option for the optimisation of existing installations is deliberate nitrification or the complete denitrification of this wastewater substream.  The systems used for this purpose at present have disadvantages in terms of energy consumption, oxygen input and sludge settling properties.

The object of this project was the investigation of biological treatment processes involving the systematic elimination of these disadvantages.  To this end, trial installations have been operated in the laboratory, and on a semi-industrial and industrial scale.  Nitrification with downstream denitrification was selected as the process system to be analysed.

Results:

  • The two-stage chemostat process investigated has been successfully applied on an industrial scale.  Process costs lie at the lower end of the range of variation indicated in the literature.
  • In order to prevent the leaching of bacteria, stable operation will require the monitoring of discharge values and the control of the influent volume.
  • On the basis of simulation calculations completed, the improvement of discharge values may be anticipated by the reduction of the nitrogen load and the attenuation of the influent peak load.

Promotion

Promoting institutions

Federal Ministry of Education and Research (BMBF)

More Project Informations

Project title:  Semi-industrial investigations of the separate two-stage biological denitrification of filtrates/centrates from sludge dewatering in municipal sewage treatment plants

Project number:  02WA9761/0

Project period:  1997 - 2001

Project region:  Germany (North Rhine-Westphalia)

Project contact:

Herr Prof. Geiger

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++ 49/201/183-3792

++ 49/201/183-3793

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Source: German National Library of Science and Technology Hannover (TIB)