Reduction of Excess Sludge Produced by Biological Treatment Processes: Effect of Ozonation on Biomass and on Sludge∗

∗This paper was presented as the introductory lecture during the IOA – EA₃G Conference “Ozone for Sludge Reduction and Control,” held in Zurich (Switzerland) on September 14th, 2006

Abstract

The excess sludge produced during biological treatment of wastewater can be reduced by treating this sludge with ozone in a specific reactor and recycling it to the biological facility. This increases the biodegradability of the inert fractions of the sludge without deteriorating the activity of the microorganisms. Ozone reacts only within the film zone near the gas/liquid interface: it is assumed that the size of the microflocs of active microorganisms is greater than the effective thickness of the film, thus protecting them from ozone. This coupled treatment produces treated water having satisfactory characteristics and a residual excess sludge that has an extremely high settling capability.

Keywords:

• Ozone
• Sludge Reduction
• Excess Sludge
• ASM1 Model
• Film Model
• Mass Transfer
• Reactor Design

ACKNOWLEDGMENT

The authors are indebted to the various participants in this research program. They would like to acknowledge the skilful technical assistance of E. Mengelle and A. Moro. They are also deeply grateful to S. Déléris, M. Salhi and D. Cesbron for their commitment during their Ph. D. studies. They also acknowledge the French agency ADEME, the Degrémont company, the Suez Environnement research centre (CIRSEE) and the EU for supporting this project (5^th R&TD program – project # EVK1-CT-2000-00050 – WIRES).

Notes

∗This paper was presented as the introductory lecture during the IOA – EA₃G Conference “Ozone for Sludge Reduction and Control,” held in Zurich (Switzerland) on September 14th, 2006

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