Sludge Floc Behavior in an Elongated Rectangular Settling Tank
Publication: Journal of Environmental Engineering
Volume 135, Issue 11
Abstract
The different sludge floc distributions along the rectangular secondary settling tank were confirmed experimentally. Along the settling tank, three different regions can be formed: the fast settling zone near the inlet, the compaction zone in the middle, and the slowly settling zone near the outlet. Further investigation of morphological change of sludge flocs also showed corresponding floc characteristics: the bigger size of particles in the front, the relatively smaller particles with high density in the middle, and the small loose flocs in the rear. These were determined by the hydraulics and floc construction. The preceding results can be used as a guide to design systems to collect loose sludge solids.
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Acknowledgments
The preparation of the paper was supported by a grant from the Eco-Star Aquatic Ecosystem Restoration Research Program.UNSPECIFIED
References
Andreadakis, A. (1993). “Physical and chemical properties of activated sludge floc.” Water Res., 27(12), 1707–1714.
APHA, AWWA, and WEF. (1995). Standard methods for the examination of water and wastewater, 19th Ed., APHA, Washington, D.C.
De Clercq, B. (2003). “Computational fluid dynamics of settling tanks: Development of experiments and rheological, settling, and scraper submodels.” Ph.D. thesis, Univ. of Gent, Belgium.
Deininger, A., Holthausen, E., and Wilderer, A. (1998). “Velocity and solids distribution in circular secondary clarifiers: Full scale measurement and numerical modelling.” Water Res., 32(10), 2951–2958.
Ekama, G. A., et al. (1997). “Secondary settling tanks: Theory, modelling and operation.” Technical Rep. No. 6, IAWQ, London.
Ekama, G. A., and Marais, P. (2004). “Assessing the applicability of the 1D flux theory to full-scale secondary settling tank design with a 2D hydrodynamic model.” Water Res., 38, 495–506.
Giokas, D. L., Daigger, G. T., Von Sperling, M., Kim, Y., and Paraskevas, P. A. (2003). “Comparison and evaluation of empirical zone settling velocity parameters based on sludge volume index using a unified settling characteristics database.” Water Res., 37(16), 3821–3836.
Govoreanu, R., Saveyn, H., Van der Meeren, P., and Vanrolleghem, P. A. (2004). “Simultaneous determination of activated sludge floc size distribution by different techniques.” Water Sci. Technol., 50(12), 39–46.
Grijspeerdt, K., and Verstraete, W. (1997). “Image analysis to estimate the settleability and concentration of activated sludge.” Water Res., 31, 1126–1134.
Jin, B., Wilén, B. M., and Lant, P. (2003). “A comprehensive insight into floc characteristics and their impact on compressibility and settleability of activated sludge.” Chem. Eng. J., 95, 221–234.
Joannis, C., Aumond, M., Dauphin, S., Ruban, G., Deguin, A., and Bridoux, G. (1999). “Modelling activated sludge mass transfer in a treatment plant.” Water Sci. Technol., 39(4), 29–36.
Kim, Y. (1995). “Solids storage function of activated sludge settling tanks during hydraulic overloads.” Ph.D. dissertation, Drexel Univ., Philadelphia.
Kim, Y., Pipes, W. O., and Chung, P. G. (1997). “Estimation of suspended solids concentration in activated sludge settling tanks.” Water Sci. Technol., 35(8), 127–135.
Krebs, P. (1991). “The hydraulics of final settling tanks.” Water Sci. Technol., 23(4–6), 1037–1046.
Krebs, P. (1995). “Success and shortcomings of clarifier modelling.” Water Sci. Technol., 31(2), 181–191.
Metcalf and Eddy. (2003). Wastewater engineering treatment, disposal, and reuse, 4th Ed., McGraw-Hill, New York.
Parker, D. S., Kinnear, D. J., and Wahlberg, E. J. (2001). “Review of folklore in design and operation of secondary clarifiers.” J. Environ. Eng., 127(6), 476–484.
Rittmann, B. E., and McCarty, P. L. (2001). Environmental biotechnology: Principles and applications, McGraw-Hill, New York.
Sezgin, M. (1980). “The role of filamentous microorganisms in activated sludge settling.” Prog. Water Technol., 12, 97–107.
Sezgin, M., Jenkins, D., and Parker, D. S. (1978). “A unified theory of filamentous activated sludge bulking.” J. WPCF, 50, 362–381.
Spicer, P. T., and Pratsinis, S. E. (1996). “Shear-induced flocculation: The evolution of floc structure and the shape of the size distribution at steady state.” Water Res., 30, 1049–1056.
Vanrolleghem, P. A., Clercq, B. D., Clercq, J. D., Devisscher, M., Kinnear, D. J., and Nopens, I. (2006). “New measurement techniques for secondary settlers: A review.” Water Sci. Technol., 53(4–5), 419–429.
Vesilind, P. (1968). “Design of prototype thickeners from batch settling tests.” Water Sew. Works, 115, 302–307.
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© 2009 ASCE.
History
Received: Sep 12, 2008
Accepted: Mar 18, 2009
Published online: Mar 25, 2009
Published in print: Nov 2009
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