Laboratory-scale assessment of vacuum-degassed activated sludge for improved settling properties
Artikel i vetenskaplig tidskrift, 2017

Vacuum degassing of activated sludge was tested at eight different Swedish wastewater treatment plants with laboratory-scale equipment in batch mode in order to evaluate its efficiency on improvement of sludge compaction and settling properties. The results show that the efficiency of the degassing technique is mainly dependent on the initial sludge volume index (SVI) of the target sludge which was found to be related to its process configuration. Facilities with full activated sludge-based nitrogen removal processes, including both nitrification and denitrification, had high SVIs (>300 mL g(-1)) and were strongly affected by vacuum degassing with reduction of SVI up to 30%. Nitrogen removal facilities also including biological phosphorus removal showed better compaction and settling properties with relatively lower SVIs and were affected to a lesser extent by degassing with SVI reduction of 10-20%. Wastewater treatment plants without full biological nitrogen removal, lacking either nitrification or denitrification (or both) processes in the activated sludge had the lowest SVIs observed with almost no effect of vacuum degassing.

sludge volume index

vacuum degassing

Activated sludge

settling properties

biological nitrogen removal


S. Haghighatafshar

Lunds universitet

Britt-Marie Wilen

Chalmers, Bygg- och miljöteknik, Vatten Miljö Teknik

A. Thunberg

Käppala Wastewater Treatment Plant

M. Hagman


Lunds universitet

A. Nyberg


J. Grundestam

Stockholm Vatten

M. Mases


J. L. Jansen

Lunds universitet

Environmental Technology (United Kingdom)

0959-3330 (ISSN) 1479-487X (eISSN)

Vol. 38 17 2193-2201





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