Flocculation-Sedimentation Performance Model for Laminar-Flow Hydraulic Flocculation with Polyaluminum Chloride and Aluminum Sulfate Coagulants
Publication: Journal of Environmental Engineering
Volume 140, Issue 3
Abstract
Mechanistically based scalable algorithms for design and operation of hydraulic flocculators were developed in this research based on observations of residual turbidity for a range of influent turbidities (5–500 NTU) and coagulant doses (0.01–0.15 mM Al), for two hydraulic residence times (800 s and 1,200 s) and for two coagulant types (polyaluminum chloride and aluminum sulfate). Kaolin clay was used as a model colloid to create synthetic raw water turbidities. Data were obtained over a range of sedimentation capture velocities using a bench-scale laminar-flow tube flocculator and quiescent settling column. Tap water with a pH of approximately 7.6 was used for all experiments. Seemingly disparate results were unified through creation of a composite dimensionless parameter that considers collision potential in the flocculator and coagulant surface coverage of colloids. One adjustable model parameter was used to fit data () from over 136 experiments to create a model for each of the two coagulants. The model was found to be applicable over a range of sedimentation tank capture velocities and accurately reflected the effects of coagulant dose, raw water turbidity, flocculator residence time, and coagulant type. The model was validated by successfully predicting results from independent data sets. The predictive model is expected to be a useful tool for evaluating design trade-offs between coagulant cost to increase surface coverage relative to capital cost to increase residence time and energy cost used to increase the velocity gradient.
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Acknowledgments
The research described in this paper was funded by the Sanjuan Foundation. This project was supported by a number of people at Cornell University, including Paul Charles, Timothy Brock, Alexander Krolick, Michael Adelman, Craig Bullington, and Dale Johnson.
References
Akers, R. J., Rushton, A. G., and Stenhouse, J. I. T. (1987). “Floc breakage: The dynamic response of the particle size distribution in a flocculated suspension to a step change in turbulent energy dissipation.” Chem. Eng. Sci., 42(4), 787–798.
American Water Works Association (AWWA). (1999). Water quality and treatment, 5th Ed., McGraw-Hill, Denver, CO.
Amirtharajah, A. (1988). “Some theoretical and conceptual views of filtration.” J. AWWA, 80(12), 36–46.
Benschoten, J. E., and Edzwald, J. K. (1990). “Chemical aspects of coagulation using aluminum salts—I. Hydrolytic reactions of alum and polyaluminum chloride.” Water Res., 24(12), 1519–1526.
Bolton Point Water System. (2012). “Drinking water quality report Southern Cayuga Lake intermunicipal water commission.” Technical Rep., Bolton Point Municipal Water System, Ithaca, NY.
Camp, T. R. (1955). “Flocculation and flocculation basins.” ASCE Trans., 120, 1–16.
Chu, Y. B., Gao, B. Y., Yue, Q. Y., and Wang, Y. (2008). “Investigation of dynamic processing on aluminum floc aggregation: Cyclic shearing recovery and effect of sulfate ion.” Sci. China, Ser. B: Chem., 51(4), 386–392.
Cleasby, J. (1984). “Is velocity gradient a valid turbulent flocculation parameter?” J. Environ. Eng., 875–897.
Dentel, S. K. (1988). “Application of the precipitation-charge neutralization model of coagulation.” Environ. Sci. Technol., 22(7), 825–832.
Gao, B. Y., Chu, Y. B., Yue, Q. Y., Wang, B. J., and Wang, S. G. (2005). “Characterization and coagulation of a polyaluminum chloride (PAC) coagulant with high Al13 content.” J. Environ. Manage., 76(2), 143–147.
Grasso, D., Subramaniam, K., Butkus, M., Strevett, K., and Bergendahl, J. (2002). “A review of non-DLVO interactions in environmental colloidal systems.” Rev. Environ. Sci. Biotechnol., 1(1), 17–38.
Great Lakes–Upper Mississippi River Board of State and Provincial Public Health and Environmental Managers. (2007). Recommended standards for water works, Health Research, Albany, NY.
Hendricks, D. W. (2006). “Guidelines and criteria for design.” Water treatment unit processes: Physical and chemical, CRC Press, Boca Raton, FL.
International Program on Chemical Safety. (1998). “Aluminum hydroxide.” 〈http://www.inchem.org/documents/icsc/icsc/eics0373.htm〉 (Jul. 15, 2012).
Ives, K. J. (1968). “Theory of operation of sludge blanket clarifiers.” Proc. Inst. Civil Eng., 39(2), 243–260.
Kawamura, S. (1991). Integrated design of water treatment facilities, Wiley, New York.
Letterman, R. D., Amirtharajah, A., and O’Melia, C. R. (1999). “Coagulation and flocculation.” Water quality and treatment, 5th Ed., R. D. Letterman, ed., American Water Works Association, McGraw-Hill, New York.
Lin, P.-H., Lion, L. W., and Weber-Shirk, M. L. (2012). “Enhanced filter performance by fluidized-bed pretreatment with (am): Observations and model simulation.” J. Environ. Eng., 419–425.
O’Melia, C. R. (1972). “Coagulation and flocculation.” Chapter 2, Physicochemical processes for water quality control, W. J. Weber, Jr., ed., Wiley-Interscience, New York.
Owen, A. T., et al. (2008). “Using turbulent pipe flow to study the factors affecting polymer-bridging flocculation of mineral systems.” Int. J. Miner. Process., 87(3–4), 90–99.
Peavy, H. S., Rowe, D. R., and Tchobanoglous, G. (1985). Environmental engineering, McGraw-Hill, New York.
Schulz, C. R., and Okun, D. A. (1984). Surface water treatment for communities in developing countries, Wiley, London.
Shin, J. Y., Spinette, R. F., and O’Melia, C. R. (2008). “Stoichiometry of coagulation revisited.” Environ. Sci. Technol., 42(7), 2582–2589.
Stumm, W., and O’Melia, C. R. (1968). “Stoichiometry of coagulation.” J. Am. Water Works Assoc., 60(5), 514–539.
Swetland, K. A. (2012). “From stock to floc: An investigation into the physical/chemical processes controlling aluminum sulfate and polyaluminum chloride behavior in a gravity powered drinking water treatment plant.” Ph.D. dissertation, Cornell Univ., Ithaca, NY.
Swetland, K. A., Weber-Shirk, M. L., and Lion, L. W. (2013). “Influence of polymeric Al-oxyhydroxide precipitate-aggregation on flocculation performance.” Environ. Eng. Sci., 30(9), 536–545.
Tse, I. C., Swetland, K., Weber-Shirk, M. L., and Lion, L. W. (2011a). “Method for quantitative analysis of flocculation performance.” Water Res., 45(10), 3075–3084.
Tse, I. C., Swetland, K., Weber-Shirk, M. L., and Lion, L. W. (2011b). “Fluid shear influences on the performance of hydraulic flocculation systems.” Water Res., 45(17), 5412–5418.
Weber-Shirk, M. L. (2008). “An automated method for testing process parameters.” 〈https://confluence.cornell.edu/display/AGUACLARA/Process+Controller+Background〉 (May 01, 2012).
Weber-Shirk, M. L., and Lion, L. W. (2010). “Flocculation model and collision potential for reactors with flows characterized by high peclet numbers.” Water Res., 44(18), 5180–5187.
Willis, R. M. (1978). “Tubular settlers—A technical review.” J. Am. Water Works Assoc., 70(6), 331–335.
Wu, X., Ge, X., Wang, D., and Tang, H. (2007). “Distinct coagulation mechanism and model between alum and high Al13-PACl.” Colloid. Surface. Physicochem. Eng. Aspect., 305(1–3), 89–96.
Xiao, F., Zhang, X., and Lee, C. (2008). “Is electrophoretic mobility determination meaningful for aluminum (III) coagulation of kaolinite suspension?” J. Colloid Interface Sci., 327(2), 348–353.
Ye, C., et al. (2007). “Alkalinity effect of coagulation with polyaluminum chlorides: Role of electrostatic patch.” Colloid. Surface. Physicochem. Eng. Aspect., 294(1–3), 163–173.
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Published In
Journal of Environmental Engineering
Volume 140 • Issue 3 • March 2014
Copyright
© 2014 American Society of Civil Engineers.
History
Received: Jul 30, 2012
Accepted: Dec 3, 2013
Published online: Jan 17, 2014
Published in print: Mar 1, 2014
Discussion open until: Jun 17, 2014
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