Selection of Sand Filtration Rates

Abstract

More and more water plants are using higher filtration rates. Several factors should be considered in selecting the design filtration rate. The consequences of higher rates in terms of water quality, filter run length, and percentage of product used in backwashing are important factors. This article, based on 3 years of pilot scale research, attempts to demonstrate how higher filtration rates affect these factors.

Selected Operations Involving Transport of a Single Fluid Phase through a Porous Medium

“…The validity of Eq. (4.1.3) has been verified on numerous occasions (e.g., Cleasby and Baumann, 1962;Eliassen, 1941;Ling, 1955), at least at the beginning of filtration (Heertjes and Lerk, 1967;Ives, 1962). The reported values of mj range from about 30 into the hundreds, but most of the values lie between 30 and 80.…”

Filtration of water and wastewater

“…As the suspensions are Newtonian fluids the shear stress at such boundaries would be proportional to viscosity; hence greater shear would be expected at lower temperatures. The flow in all types of filters is laminar during the entire filtration cycle, well demonstrated by Cleasby and Baumann, 29 and not opposed in any of the symposia or report papers. Although changes in viscosity and density will alter the Reynolds' Number, the magnitudes of such changes cannot be expected to alter the flow regime in any substantial way.…”

“…43 The second view is that the mat is a continuous compressible cake, as found in chemical engineering processes, with no holes in it, which gave rise to a power law relationship. 29 Interpretation of head loss data is equivocal, but the proponent of the first view has claimed to have observed the holes in the surface mat in experimental filters.…”

Use of digital computer in design of diatomite filtration plants

“…Accordingly, most theories are based on sand (clean uniform sand at that) and have found little application in diatomite filtration. Earlier work on sand filtration was well sum marized in the excellent study on sand filtration rates made by Cleasby in 1960 (12,13). Another excellent paper on sand filtration by Camp was published in 1964 (9).…”