Water Science & Technology Vol 63 No 12 pp 3034–3038 © IWA Publishing 2011 doi:10.2166/wst.2011.607

Oxygen transfer in activated sludge – new insights and potentials for cost saving

J. Henkel, P. Cornel and M. Wagner

The a-factor has the greatest impact on the calculation of the required standard oxygen transfer rate (SOTR) in activated sludge systems equipped with submerged aeration systems. Knowing the dependencies of the a-factor leads to a better design of the aeration devices and, consequently, to a more efficient use of aeration energy. Applying the current state of knowledge about oxygen transfer leads to the conclusion that, in contrast to current opinion, simultaneous aerobic stabilization requires the same SOTR as conventional activated sludge systems with advanced nutrient removal, even though a higher organic load is degraded.

Keywords: a-factor; MLVSS; oxygen transfer; SOTR; SRT

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