A method for characterizing the complete settling process of activated sludge.

Based on batch settling tests, a model describing the compression settling process of activated sludge was developed and validated by experiments. Furthermore, a theoretical equation for determining the critical point when the compression settling stage commences, and a new velocity function for the compression settling were deduced from the model. By combining the new model and the conservation of mass, it was proved that the Vesilind function was also capable of describing the compression settling velocity on condition that the appropriate parameters were estimated. Dividing the complete settling process of activated sludge into the zone settling and compression settling stages, and describing them by the Vesilind function with different parameter sets was more reasonable for characterizing the complete settling process of activated sludge. The method was applied to predict the sludge blanket height during batch settling tests, and the results showed that the settling processes could be simulated well.

[1]  Peter A. Vanrolleghem,et al.  Estimation of sludge sedimentation parameters from single batch settling curves , 2000 .

[2]  L. Härtel,et al.  A Dynamic Secondary Clarifier Model including Processes of Sludge Thickening , 1992 .

[3]  G. Ekama,et al.  Assessing the applicability of the 1D flux theory to full-scale secondary settling tank design with a 2D hydrodynamic model. , 2004, Water research.

[4]  F. Colin,et al.  Settling velocity model of activated sludge , 1993 .

[5]  Scott A. Wells,et al.  Numerical model of sedimentation/thickening with inertial effects , 1999 .

[6]  G. J. Kynch.  A theory of sedimentation , 1952 .

[7]  Peter A. Vanrolleghem,et al.  Analysis and simulation of the sludge profile dynamics in a full-scale clarifier , 2005 .

[8]  G. Daigger.  Development of refined clarifier operating diagrams using an updated settling characteristics database , 1995 .

[9]  Mogens Henze,et al.  Modelling of the Secondary Clarifier Combined with the Activated Sludge Model No. 1 , 1992 .

[10]  G. A. Ekama,et al.  Sludge settleability and secondary settling tank design procedures , 1986 .

[11]  A. E. Greenberg,et al.  Standard methods for the examination of water and wastewater : supplement to the sixteenth edition , 1988 .

[12]  James L. Barnard,et al.  Secondary settling tanks : theory, modelling, design and operation , 1997 .

[13]  Bernhard Wett,et al.  A straight interpretation of the solids flux theory for a three-layer sedimentation model. , 2002, Water research.

[14]  Rafael Font,et al.  A mathematical model to simulate batch sedimentation with compression behavior , 1998 .

[15]  Francesco Pirozzi,et al.  A generalized settling approach in the numerical modeling of sedimentation tanks , 1998 .

[16]  Wolfgang Rodi,et al.  Density Currents and Shear-Induced Flocculation in Sedimentation Tanks , 1992 .

[17]  René Dupont,et al.  A one-dimensional model for a secondary settling tank including density current and short-circuiting , 1995 .

[18]  A. R. Pitman.  Settling of Nutrient Removal Activated Sludges , 1985 .

[19]  Marcos von Sperling,et al.  Comparison and evaluation of empirical zone settling velocity parameters based on sludge volume index using a unified settling characteristics database. , 2003, Water research.

[20]  R. Otterpohl,et al.  Dynamic Models for Clarifiers of Activated Sludge Plants with Dry and Wet Weather Flows , 1992 .

[21]  W. Verstraete,et al.  On-line quantification of settling properties with in-sensor-experiments in an automated settlometer , 1996 .

[22]  I. Takács.  A dynamic model of the clarification-thickening process , 1991 .