Mathematical Modeling And Experimental Studies Of Up-flowing And Moving-bed Filter

The technology of moving-bed filtration is a kind of successful filtration technology,developed recently abroad. It is capable of accomplishing continuously the material filteringand wash-cleaning cycle simultaneously. Thus, the filtering bed is kept steadily clean andhigh-efficient, providing high-quality effluent water stabilized. Domestic investigation in thisfield is in the preliminary stage, urgently demanding of further study and applications.This paper reports the experimental study, on a small-sized installment, about the keyfactors, affecting the effluent water quality and efficiency of the up-flowing & moving bedfilter. The reasonable running condition are given as follows: filtering velocity v＜8m/h,filtering bed thickness h=70cm, filter material diameter d=0.7～1.0mm, sand recycling speedW_z=1.5—3mm/min.Mathematical model of the moving-bed filter is established based on the filtration theoryand the operation condition analysis. Behavior and resistance of the flowing water within thefiltering layer are studied. According to Darcy's formula and Kozeny-Carmon equation, thefiltration resistance model of clean filtration bed is deduced. Combining the physical model ofdeep layer filtration wit the filtration bed cells conception, the filtration resistance model ofthe filtering layer for intercepting impurity is established. Relationships between filtrationresistance and the variation of different parameters are defined. These results are valuable tothe applications of this kind of water-treatment technique.