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Modeling Nonsteady‐State Conditions and Kinetics of Mass Transport for Hydrophobic Compounds in Activated‐Sludge Treatment
Author(s) -
Rittmann Bruce E.,
Lee KuanChun,
Shi Jay,
McAvoy Drew C.
Publication year - 2003
Publication title -
water environment research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.356
H-Index - 73
eISSN - 1554-7531
pISSN - 1061-4303
DOI - 10.2175/106143003x141060
Subject(s) - kinetics , chemistry , mass transfer , activated sludge , aqueous solution , adsorption , steady state (chemistry) , hydrophobic effect , chemical engineering , aqueous two phase system , thermodynamics , phase (matter) , chromatography , organic chemistry , sewage treatment , environmental engineering , physics , quantum mechanics , engineering
A new model that describes the fate of hydrophobic and volatile organic compounds in activated‐sludge treatment includes two novel features. First, all of the mass balances are nonsteady state, which allows the model to describe the effects of transients in loading, temperature, or operation. Second, the model describes the mass transfer of hydrophobic compounds with kinetics, not equilibrium. A series of examples demonstrate the new features of the model and how they can be important. When the kinetics of mass transfer are not fast, hydrophobic compounds remain significantly out of equilibrium, even when the system is operating at steady state. When the loading of a hydrophobic compound increases, its aqueous‐phase concentration approaches (but does not quite reach) its steady‐state concentration much more rapidly than does the density of the adsorbed hydrophobic compound. Finally, the importance of mass‐transport kinetics between the aqueous and sorbed phases suggests that research should be focused on this poorly understood mechanism in activated sludge.