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Pilot Identifies Best Backwash Pretreatment
Author(s) -
Lew Julia,
Patawaran Rowena
Publication year - 2000
Publication title -
opflow
Language(s) - English
Resource type - Journals
eISSN - 1551-8701
pISSN - 0149-8029
DOI - 10.1002/j.1551-8701.2000.tb02286.x
Subject(s) - filtration (mathematics) , water treatment , filter (signal processing) , environmental science , slow sand filter , pilot plant , settling , environmental engineering , cryptosporidium , sand filter , aeration , portable water purification , giardia lamblia , pulp and paper industry , waste management , wastewater , engineering , biology , microbiology and biotechnology , mathematics , statistics , electrical engineering , feces
Filter backwash water can contain significantly greater concentrations of Giardia lamblia and Cryptosporidium oocysts than are present in the source water. The pending Filter Backwash Rule will require that water recycled to the treatment plant must be returned prior to the point of primary coagulant addition and a cycle self‐assessment be performed to reduce the pathogen threat. This article describes how the Betasso Water Treatment Plant in Boulder, Colorado, conducted pilot studies that determined the best pretreatment technology for the plant would be dissolved air flotation. The necessary elements of a backwash pretreatment program are listed, along with a discussion of several processes that were evaluated that included: ultraviolet (UV) light disinfection and ozonation; membrane filtration; diatomaceous earth filtration; ballasted floc; dissolved air flotation; and, inclined (Lamella) plate settling.