Migration and deposition of fine particles in a porous filter and alluvial deposit: laboratory experiments
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ORIGINAL PAPER
Migration and deposition of fine particles in a porous filter and alluvial deposit: laboratory experiments Suzanne Faber 1,2,3 & Ali Al-Maktoumi 1 & Anvar Kacimov 1 & Hamed Al-Busaidi 1 & Said Al-Ismaily 1 & Mohamed Al-Belushi 1
Received: 21 June 2015 / Accepted: 5 January 2016 / Published online: 31 March 2016 # Saudi Society for Geosciences 2016
Abstract The filtration of fine solid particles suspended in water by two porous media, a column of glass beads (2-mm diameter) and a column of artificial sand (1–1.6-mm diameter), was studied. A suspension of fine particles (equal and lower than silt size—called silt in this paper) in water (concentration, δ, of 25 mg/L) flows vertically through the columns. The hydraulic head and time—distance—varying δ in seeping water were measured along the depth of the column for a period of about 80 h. In the column of glass beads, most of the silt gets retained in the upper part of the column. The silt-retention front migrated downward continuously during the 80 h that the experiment lasted. In artificial sand, during the first 30 h, the top few centimeters of the filter contribute
* Ali Al-Maktoumi [email protected]; [email protected] Suzanne Faber [email protected] Anvar Kacimov [email protected] Hamed Al-Busaidi [email protected] Said Al-Ismaily [email protected] Mohamed Al-Belushi [email protected]
1
Department of Soils, Water, and Agricultural Engineering, College of Agricultural and Marine Sciences, Sultan Qaboos University, P.O. Box 34, Al-Khoud 123, Muscat, Sultanate of Oman
2
Isle Utilities, UKP.O. Box 621, Epsom KT18 6UJ
3
University of Amsterdam, Amsterdam, The Netherlands
the most to the total retention of suspension. At a later stage, however, it is a deeper section of the column that contributes the most. This downward shift continues until the top layers of the column start to fully clog and the silt front stops moving down. The hydraulic conductivity, K, shows a sharp change at the interface below and above the silt retention front. It drops by 30–50 % due to the clogging for glass beads and artificial sand, respectively. The findings of this study are of paramount importance for properly managing and administrating the recharge dams especially in arid climate.
Keywords Filtration . Porous medium . Recharge dam . Siltation . Hydraulic conductivity
Abbreviations A Cross-sectional area h Hydraulic pressure dh Hydraulic pressure drop K Hydraulic conductivity Ka Apparent, or average, hydraulic conductivity L The length of the column M Mass Mret Retained mass NTU Turbidity MRMWR Ministry of Regional Municipality and Water Resources Q Volumetric flow rate t Time x Distance δ Volume concentration of solids in liquid phase δ0 Initial volume concentration of solids in liquid phase
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Introduction Sand filters get fouled or even clogged if the filtrate contains suspended particles. This requires tedious recuperation, backwashing or even replacement of the filter filling. Similarly, in geotechnical engineering, the
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