Optimization of Gravity-Driven Hydraulic Flocculators to Treat Peat Extraction Runoff Water
Publication: Journal of Irrigation and Drainage Engineering
Volume 142, Issue 2
Abstract
Peatland drainage and peat extraction result in runoff water rich in humus, sediments, and nutrients that requires simple purification methods to prevent pollution of surface waters. Chemical treatment of drainage water has been suggested as best management practice. However, good chemical purification results require flocculators to achieve efficient particle aggregation. This study evaluated gravity-driven hydraulic flocculators using full-scale three-dimensional (3D) computational fluid dynamic (CFD) turbulence models to simulate hydraulics, combined with data obtained in jar tests to estimate optimal mixing conditions for coagulation [velocity gradient (-values)]. The CFD model was first run for several barrier configurations. The optimal structure was then tested for different ratios of distance between barriers [or opening slot width ()] and flocculator width (). The relationship between distribution of -values and the target value of was determined for different designs. The best ratio was found to be . For this ratio, the flow depth was the only variable parameter that needed to be optimized by the CFD model to achieve target -values.
Get full access to this article
View all available purchase options and get full access to this article.
Acknowledgments
Special thanks goes to Vapo Oy for funding this study and the authors would like to thank Maa-ja vesitekniikan tuki, TES-Tekniikan edistämissäätiö and OLVI-säätiö for their support.
References
Abbas, H., Nasr, R., and Seif, H. (2006). “Study of waste stabilization pond geometry for the wastewater treatment efficiency.” Ecol. Eng., 28(1), 25–34.
Andriesse, J. P. (1988). “Nature and management of tropical peat soils.”, Food and Agriculture Organization of the United Nations (FAO), Rome.
Bhargava, D. S., and Ojha, C. S. P. (1993). “Models for design of flocculating baffled channels.” Water Res., 27(3), 465–475.
Bratby, J. (2006). Coagulation and flocculation in water and wastewater treatment, IWA Publishing, London.
Bridgeman, J., Jefferson, B., and Parsons, S. A. (2010). “The development and application of CFD models for water treatment flocculators.” Adv. Eng. Software, 41(1), 99–109.
Camp, T. R. (1955). “Flocculation and flocculation basins.” Trans. ASCE, 120(1), 1–16.
Camp, T. R., and Stein, P. C. (1943). “Velocity gradients and internal work in fluid motion.” J. Boston Soc. Civ. Eng., 30, 219–237.
COMSOL AB. (2013). “CFD module user’s guide.” Stockholm, Sweden, 〈http://localhost:8090/doc/com.comsol.help.cfd/CFDModuleUsersGuide.pdf〉 (Mar. 9, 2015).
Crittenden, J. C., Trussell, R. R., Hand, D. W., Howe, K. J., and Tchobanoglous, G. (2012). “6-10: Mixing theory and practice.” MWH’s water treatment: Principles and design, Wiley, Hoboken, NJ, 362–367.
Ellis, K., and Tang, S. (1991). “Wastewater treatment optimization model for developing world. I: Model development.” J. Environ. Eng., 501–518.
Ellis, K., and Tang, S. (1994). “Wastewater treatment optimization model for developing world. II: Model testing.” J. Environ. Eng., 610–624.
Haarhoff, J. (1998). “Design of around-the-end hydraulic flocculators.” J. Water Supply Res. Technol. AQUA, 47(3), 142–152.
Haarhoff, J., and van der Walt, J. J. (2001). “Towards optimal design parameters for around-the-end.” J. Water Supply Res. Technol. AQUA, 50(3), 149–159.
Heiderscheidt, E., Leiviskä, T., and Kløve, B. (2015). “Chemical treatment response to variations in non-point pollution water quality: Results of a factorial design experiment.” J. Environ. Manage., 150, 164–172.
Heiderscheidt, E., Saukkoriipi, J., Ronkanen, A., and Kløve, B. (2013). “Optimisation of chemical purification conditions for direct application of solid metal salt coagulants: Treatment of peatland-derived diffuse runoff.” J. Environ. Sci., 25(4), 659–669.
Hudson, H. E., and Wolfner, J. P. (1967). “Design of mixing and flocculating basins.” J. Am. Water Works Assn., 59(10), 1257–1267.
Jarvis, P., Jefferson, B., Gregory, J., and Parsons, S. A. (2005). “A review of floc strength and breakage.” Water Res., 39(14), 3121–3137.
Kawamura, S. (1973). “Coagulation considerations.” J. Am. Water Works Assn., 65(6), 417–423.
Kawamura, S. (2000). Integrated design and operation of water treatment facilities, Wiley, New York.
Kløve, B. (2001). “Characteristics of nitrogen and phosphorus loads in peat mining wastewater.” Water Res., 35(10), 2353–2362.
Kløve, B., et al. (2012). “Pollution load of drained water from peat mines prediction and new controlling methods.” Suomen ympäristö, Helsinki, Finland.
Krkosek, W. H., et al. (2012). “Treatment performance of wastewater stabilization ponds in Canada’s far north.” Cold Reg. Eng., 612–622.
Leentvaar, J., and Ywema, T. S. J. (1980). “Some dimensionless parameters of impeller power in coagulation-flocculation processes.” Water Res., 14(2), 135–140.
Li, T., Pannala, S., and Shahnam, M. (2014). “CFD simulations of circulating fluidized bed risers, part II, evaluation of differences between 2D and 3D simulations.” Powder Technol., 254, 115–124.
Marttila, H., and Kløve, B. (2008). “Erosion and delivery of deposited peat sediment.” Water Resour. Res., 44(6), W06406.
Marttila, H., and Kløve, B. (2009). “Retention of sediment and nutrient loads with peak runoff control.” J. Irrig. Drain. Eng., 210–216.
McConnachie, G. L., Folkard, G. K., Mtawali, M. A., and Sutherland, J. P. (1999). “Field trials of appropriate hydraulic flocculation processes.” Water Res., 33(6), 1425–1434.
McConnachie, G. L., and Liu, J. (2000). “Design of baffled hydraulic channels for turbulence-induced flocculation.” Water Res., 34(6), 1886–1896.
Montgomery, J. M. (1985). Water treatment: Principles and design, Wiley, New York.
Moussiere, S., Roubaud, A., Boutin, O., Guichardon, P., Fournel, B., and Joussot-Dubien, C. (2012). “2D and 3D CFD modelling of a reactive turbulent flow in a double shell supercritical water oxidation reactor.” J. Supercrit. Fluids, 65, 25–31.
Olukanni, D. O., Adekalu, K. O., and Ducoste, J. J. (2012). “Hydraulic modelling and optimization of a wastewater treatment system for developing nations using computational fluid dynamics.” Int. Conf. on Clean Technology and Engineering Management, Covenant Univ., Ota, Nigeria, 51–71.
Olukanni, D. O., and Ducoste, J. J. (2011). “Optimization of waste stabilization pond design for developing nations using computational fluid dynamics.” Ecol. Eng., 37(11), 1878–1888.
Ouellette, C., Courtenay, S. C., St-Hilaire, A., and Boghen, A. D. (2006). “Impact of peat moss released by a commercial harvesting operation into an estuarine environment on the sand shrimp Crangon septemspinosa.” J. Appl. Ichthyol., 22(1), 15–24.
Ronkanen, A., and Kløve, B. (2008). “Hydraulics and flow modelling of water treatment wetlands constructed on peatlands in northern Finland.” Water Res., 42(14), 3826–3836.
Schilstra, A. J. (2001). “How sustainable is the use of peat for commercial energy production?” Ecol. Econ., 39(2), 285–293.
Schulz, C. R., and Okun, D. A. (1992). Surface water treatment for communities in developing countries, Wiley, New York.
Shannon, M. A., Bohn, P. W., Elimelech, M., Georgiadis, J. G., Marinas, B. J., and Mayes, A. M. (2008). “Science and technology for water purification in the coming decades.” Nature, 452(7185), 301–310.
Shilton, A. N., and Mara, D. D. (2005). “CFD (computational fluid dynamics) modelling of baffles for optimizing tropical waste stabilization pond systems.” Water Sci. Technol., 51(12), 103–106.
Smethurst, G. (1988). Basic water treatment of application worldwide, ASCE, Reston, VA.
Swamee, P. K. (1996). “Design of flocculating baffled channel.” Environ. Eng., 1046–1048.
Tse, I. C., Swetland, K., Weber-Shirk, M. L., and Lion, L. W. (2011). “Fluid shear influences on the performance of hydraulic flocculation systems.” Water Res., 45(17), 5412–5418.
Vadasarukkai, Y. S., Gagnon, G. A., Campbell, D. R., and Clark, S. C. (2011). “Assessment of hydraulic flocculation processes using CFD.” J. Am. Water Works Assn., 103(11), 66–80.
Vasander, H., et al. (2003). “Status and restoration of peatlands in northern Europe.” Wetlands Ecol. Manage., 11(1/2), 51–63.
Wilcox, D. C. (1998). Turbulence modeling for CFD, DCW Industries, La Canada, CA.
Wood, M. G., Greenfield, P. F., Howes, T., Johns, M. R., and Keller, J. (1995). “Computational fluid dynamic modelling of wastewater ponds to improve design.” Water Sci. Technol., 31(12), 111–118.
Wood, M. G., Howes, T., Keller, J., and Johns, M. R. (1998). “Two dimensional computational fluid dynamic models for waste stabilisation ponds.” Water Res., 32(3), 958–963.
Ympäristöministeriö (Ministry of the Environment). (2013). “Turvetuotannon ympäristönsuojeluohje (Guidelines for environmental protection in peat mining).” 〈www.ym.fi/julkaisut〉 (Sep. 29, 2014).
Information & Authors
Information
Published In
Copyright
© 2015 American Society of Civil Engineers.
History
Received: Dec 3, 2014
Accepted: Jul 20, 2015
Published online: Sep 21, 2015
Published in print: Feb 1, 2016
Discussion open until: Feb 21, 2016
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.