Effect of Filtration Velocity and Rapid Sand Filter Bed Depth on Removal Efficiency of Suspended Particles

Document Type : Research Paper


1 . Grad. Student of Irrigation and Drainage, College of Agriculture, Bu-Ali Sina University, Hamedan

2 Assist. Prof. of Water Eng., College of Agriculture, Bu-Ali Sina University, Hamedan

3 Assoc. Prof. of Pedology, College of Agriculture, Isfahan University of Tech., Isfahan


Removal of particles by filter is a complex process in water treatment. Several factors are involved such as shape and size of filter grains, suspended particle concentration, filtration velocity and filter bed depth. The objective of this study was to evaluate effects of filtration velocity and rapid sand filter bed depth on removal efficiency of suspended particles. Four filtration velocities (0.086, 0.11, 0.14 and 0.17 cm/sec) and three depths of filter bed (25, 50 and 60 cm) were used in this study. Kaolinite concentration in inlet suspension above the filter bed was 100 ppm in each experiment. Silica sand was used as the filter medium with an average diameter of 0.51 mm. The results showed that removal efficiency of suspended particles was greater in low filtration velocity (i.e. 0.086 cm/sec) than high filtration velocities in the filters with specific bed depth. Removal efficiency of  suspended particles increased with increasing filter bed depth from 25 to 50 cm in all of the experiments but there was no significant difference between obtained results in the filter bed with 50 and 60 cm depths (a=0.01). Head loss development was greater in low velocities than high velocities. Head loss development was greater in 25 cm depth than 50 and 60 cm depths in all of the filtration velocities. Favorable depth and filtration velocity was obtained 50 cm and 0.17 cm/sec, respectively.


1- Skouras, E.D., Burganos, V.N., Paraskeva, C.A., and Payatakes, A.C. (2007). “ Simulation of the dynamic behavior of horizontal granular filters.” J. Separation, and Purification Technol., 56, 325-339.
2- Vigneswaran, S., and Song, C.J. (1986). “Mathematical modeling of the entire cycle of deep bed filtration.” J. Water, Air and Soil Poll., 29 (2), 155-164.
3- Vigneswaran, S., and  Thiyagaran, M. (1984). “Application of filtration theories to groundwater recharge problems.” J. Water, Air and Soil Poll., 2 (4), 417-428.
4- Boller, M.A., and Kavanaugh, M.C. (1995). “Particle characteristics and head loss increase in granular media filtration.” J. Wat. Res., 29(4), 1139-1149.
5- Han ko, C., and Elimelech, M. (2000). “The "shadow effect" in colloid transport and deposition dynamics in granular porous media: Measurements and mechanisms.” J. Environ. Sci. Technol., 34(17), 3681-3689.
6- Darby, J.L., and Lawler, D.F. (1990). “Ripening in depth filtration: Effect of particle size on removal and head loss.” J. Environ. Sci. Technol., 24(7), 1069-1079.
7- Kau, S.M., and Lawler, D.F. (1995). “Dynamics of deep bed filtration: Velocity, depth, and media.” J. Environ. Eng., 121(12), 850-859.
8- Tufenkji, N., and Elimelech, M. (2004). “Correlation equation for predicting single-collector efficiency in physicochemical filtration saturated porous media.” J. Environ. Sci. Technol., 38(2), 529-536.
9- Jegatheesan, V., and Vigneswaran, S. (2005). “Deep bed filtration: mathematical models and observations.” J. Critical Review in Environ. Sci. Technol., 35, 515-569.
10- Wiesner, M.R. (1999). “Morphology of particle deposits.” J. Environ. Eng., 125(12), 1124-1132.
11- Chang, Y.I., and Chan, H.C. (2005). “Network simulation for deep bed filtration of Brownian particles- a supplement.” J. Chem. Engr. Sci., 60 (10), 2827-2831.
12- Chang, Y.I., Chen, S.C., Chan, H.C., and Lee, E. (2004). “Network simulation for deep bed filtration of Brownian particles.” J. Chem. Eng. Sci., 59 (9), 4467-4479.
13- Banejad, H., Mokari, M., Mosaddeghi, M., and Doae, Y. (2008). “Evaluation of particles removal efficiency in rapid sand filters by changing particle concentration and media grain size.” J. of Water and Wastewat., 68, 40-47. (In Persian)
14- Punmia, B.C., Jain, A.K., and Jain, A.K. (2003). Water supply engineering, Laxmi pub.,New Delhi.
15- Shin, C. (2006) “Finite element simulation of deep bed filtration.” J. Chem.  Engr. Sci., 61, 2324-2329.
16- Mays, D.C., and Hunt, J.R. (2005). “Hydrodynamic aspects of particle clogging in porous media.” J. Environ. Sci. Technol., 39(2), 577-584.
17- Veerapaneni, S., and Wiesner, M.R. (1997). “Deposit morphology and head loss development in porous media.” J. Environ. Sci. Technol., 31(10), 2738-2744.