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Drinking Water Engineering and Science An interactive open-access journal

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Drink. Water Eng. Sci., 5, 73-85, 2012
© Author(s) 2012. This work is distributed
under the Creative Commons Attribution 3.0 License.
07 Dec 2012
Low-cost multi-stage filtration enhanced by coagulation-flocculation in upflow gravel filtration
L. D. Sánchez1, L. M. Marin1, J. T. Visscher2, and L. C. Rietveld3 1Universidad del Valle, Facultad de Ingeniería, Instituto Cinara, Cali, Colombia
2JTF-Rotterdam BV, Rotterdam, The Netherlands
3Delft University of Technology, P.O. Box 5084, 2600 GA Delft, The Netherlands
Abstract. This paper assesses the operational and design aspects of coagulation and flocculation in upflow gravel filters (CF-UGF) in a multi-stage filtration (MSF) plant. This study shows that CF-UGF units improve the performance of MSF considerably, when the system operates with turbidity above 30 NTU. It strongly reduces the load of particulate material before the water enters in the slow sand filters (SSF) and therewith avoids short filter runs and prevents early interruption in SSF operations. The removal efficiency of turbidity in the CF-UGF with coagulant was between 85 and 96%, whereas the average efficiency without coagulant dosing was 46% (range: 21–76%). Operating with coagulant also improves the removal efficiency for total coliforms, E-coli and HPC. No reduction was observed in the microbial activity of the SSF, no obstruction of the SSF bed was demonstrated and SSF runs were maintained between 50 and 70 days for a maximum head loss of 0.70 m. The most important advantage is the flexibility of the system to operate with and without coagulant according to the influent turbidity. It was only necessary for 20% of the time to operate with the coagulant. The CF-UGF unit represented 7% of total construction costs and the O&M cost for the use of coagulant represented only 0.3%.

Citation: Sánchez, L. D., Marin, L. M., Visscher, J. T., and Rietveld, L. C.: Low-cost multi-stage filtration enhanced by coagulation-flocculation in upflow gravel filtration, Drink. Water Eng. Sci., 5, 73-85, doi:10.5194/dwes-5-73-2012, 2012.
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