Functioning of filter structures in changing velocity conditions over time

Abstract

One of the main constructions, which are used for preparing water of necessary quality, is rapid filter. Functioning of such structures, as a rule, takes place in free-flow regime. Structures operation time depends on two main parameters: water treatment quality and provision of necessary calculated discharge. In this case it is accepted that fluid velocity in a filter bed is constant. In fact, functioning of such structures can differ from reviewed ones. A variant of rapid filters operation under substantial variation of filtration velocity was analyzed in the article. Specific operation conditions of such structures and differential equations, which describe water flow in filter medium and intensity of contaminants removal, were reviewed. As the result of conducted research, variation over time of suspended particles concentration in the filtrate, filter productivity, quantity of not clari- fied suspension which accumulates over filter bed under various sorption properties of filter medium was shown. Engineering calculation methodology of filtration structures main characteristics, including technological filtration time, filtration cycle duration and optimal filter media height were suggested. Mentioned calculated relations and equations were illustrated by example series with typical initial data.