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Vorträge und Posterpräsentationen (mit Tagungsband-Eintrag):

V. Parravicini, K. Svardal, R. Hornek, H. Kroiss:
"Aeration of anaerobically digested sewage sludge for COD and Nitrogen removal: optimization at large-scale";
Vortrag: IWA Specialist Conference `Moving Forward - Wastewater Biosolids Sustainability: Technical, Managerial and Public Synergy´, Moncton, New Brunswick, CANADA; 24.06.2007 - 27.06.2007; in: "Manuscrips", (2007), 7 S.



Kurzfassung englisch:
The paper will report about the experiences matured at an Austrian large wastewater
treatment plant of 720.000 population equivalents, where anaerobically digested sewage sludge is
further stabilised under aerobic conditions. Enhanced stabilisation of the anaerobically digested
sludge was required at the plant in order to get a permit for landfill disposal of the dewatered
stabilized sludge. By implementing a post-aeration treatment (SRT∼6d; 36°C) after anaerobic
digestion the organic content of the anaerobically well digested sludge can be decreased by 16%.
Investigations on site showed that during digested sludge post-aeration anoxic phases for
denitrification are needed to provide stable process conditions. In this way the pH value can be kept
in a more favourable range for micro-organisms and concrete structures. Additionally, inhibition of
the biological process due to nitrite accumulation can be avoided. By optimising the aeration/pause
ratio ~45% of total nitrogen in digested sludge can be removed. This significantly improves
nitrogen removal efficiency at the wastewater treatment plant. NH4-removal occurs mainly through
nitritation and denitritation with an efficiency of 98%. The costs/benefit analysis shows that postaeration
of digested sludge results in an increase of total annual costs for wastewater treatment of
only 0.84%, corresponding to 0.19 Euro/pe/a. Result of molecular biological analyses (DGGE)
indicate that all four ammonium-oxidizing bacteria species present in activated sludge can survive
anaerobic digestion, but only two of them can adapt in the digested sludge post-aeration tanks.
Additionally, in the post-aerated digested sludge a further ammonium-oxidizing bacteria species
was identified.

Schlagworte:
Enhanced sewage sludge stabilisation; digested sludge aeration; nitrogen removal in

Erstellt aus der Publikationsdatenbank der Technischen Universität Wien.