Granular Bed and Precoat Filtration

Abstract

Abstract Various filtration processes are used in potable water treatment. Granular bed and precoat filtration processes are described in this article, and focus is on descriptions of these processes and their particle removal efficiencies. Filtration processes are some of the major tools that are used to minimize microbial pathogens in drinking water, so the descriptions of their removal efficiencies contained herein emphasize their removal of microbes. This type of efficiency is characterized by a term called log removal, which is defined as log C o / C , where C o and C are the pathogen concentrations in a filter's inlet and outlet flows, respectively. Thus, a 1‐log removal is equivalent to 90% removal. Current drinking water regulations target log removals of pathogens. Filter performance is also based on the amount of turbidity in the filtered water. Turbidity is a measure of water clarity. Turbidity reduces the aesthetic acceptability of drinking water and also shields pathogens from disinfectants that are added downstream of filters.