Enhanced Ripening of Slow Sand Filters
Publication: Journal of Environmental Engineering
Volume 126, Issue 12
Abstract
While successful in removing turbidity and pathogens from drinking water, slow sand filters require ripening periods at the beginning of each filter run. The premise of this research was that it should be possible to enhance the ripening of slow sand filters. Potential ripening agents were screened by assessing their interaction with the surface of filtration media and turbidity particles. Four natural organic polymers and nine synthetic polymers were investigated for their potential to enhance filter ripening. Of the 13 modifying agents considered, none conclusively sorbed to the filter media, and only one, a synthetic polymer, interacted with kaolin particles. A filter modified with continuous feed of the polymer ripened successfully and produced water with turbidity below 1.0 NTU in about 24 h. Most turbidity removal in the treated filter occurred in the schmutzdecke rather than within the depth of the filter bed. Hence, the mechanism of enhanced ripening in this case probably was particle agglomeration with resulting acceleration of particle deposition at the filter surface accompanied by straining or attachment to previously removed particles.
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Information & Authors
Information
Published In
Journal of Environmental Engineering
Volume 126 • Issue 12 • December 2000
Pages: 1153 - 1157
History
Received: Aug 2, 1998
Published online: Dec 1, 2000
Published in print: Dec 2000
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