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The goal of this research was to study the removal mechanisms of slow sand filtration (SSF) withspecial emphasis on the comparing of optimum summer conditions to more severe winterconditions as observed in the northern latitudes and mountainous regions. An effort wasmade to verify if the biological characteristics of the sand media are correlated to themicrobial removal performance of the SSF at the different temperatures encountered inthe New England area.The pilot filtration studies were conducted on the NarrowsPond surface water supply for the town of Winthrop, Maine. This site was chosen becauseaccording to the Winthrop Water Utilities the organic precursor content in the sourcewater increased by roughly 10% from 2003 to 2004. Two pilot SSFs, Filter 1 (F1) andFilter 2 (F2), were operated simultaneously in the pipe gallery of the Winthrop, Maine watertreatment facility. The first microbial challenge took place in July of 2004 and wasfollowed by 8 more filter challenges with the most recent event taking place in March2006. A final challenge is planned for July 2006. Each of the filter challengeswas followed a week later by a filter coring event where sand samples were collected.This week between the microbial challenge event and the coring event was necessary dueto the distance of the sampling site to the laboratory and also due to the amount ofsamples collected from those two events. Both filters operated continuously for theduration of the study for approximately 600 days and were only taken off-line for sandsample collection or cleaning/scouring purposes. A low amount of ozone wascontinuously pumped into F1 and resulted in longer filter runs in F1 than those on F2.Ozone residuals in F1 ranged from below detection limit to 1.10 mg Osub3/sub mg/L. Includes 23 references, tables, figures.

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Edition: Vol. - No. Published: 06/01/2006 Number of Pages: 18File Size: 1 file , 390 KB