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.
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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.
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Published In
Journal of Irrigation and Drainage Engineering
Volume 142 • Issue 2 • February 2016
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
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