The Importance of Aerobic Mixing, Biofilm Thickness Control and Modeling on the Success or Failure of IFAS Systems for Biological Nutrient Removal
Abstract:Research on full scale Integrated Fixed Film Activated Sludge (IFAS) and Mobile Bed Biofilm Reactor (MBBR) systems showed that problems developed with excessive biofilm thickness when the mixing and roll patterns decreased. Evaluated media included fixed bed cord media, moving bed sponge media and moving bed plastic media. Three strategies are recommended. (1) Process modeling should be used to determine the soluble biodegradable COD (SCODbio) and N profiles along the aerobic cells and adjust the volume, quantity of media or MLSS MCRT if SCODbio concentration in any cell is excessive. (2) Where process changes cannot lower the SCODbio and control thickness, the mixing and aeration systems should be improved by switching to a more vigorous roll pattern with coarse bubble diffusers and jet mixing. (3) The type of media selected should be such that the biofilm specific surface area does not decrease significantly as the thickness increases from 0.1 to 1 mm.
Document Type: Research Article
Publication date: 2007-11-01
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