The goal of this research was to study the removal mechanisms of slow sand filtration (SSF) with
special emphasis on the comparing of optimum summer conditions to more severe winter
conditions as observed in the northern latitudes and mountainous regions. An effort was
made to verify if the biological characteristics of the sand media are correlated to the
microbial removal performance of the SSF at the different temperatures encountered in
the New England area.
The pilot filtration studies were conducted on the Narrows
Pond surface water supply for the town of Winthrop, Maine. This site was chosen because
according to the Winthrop Water Utilities the organic precursor content in the source
water increased by roughly 10% from 2003 to 2004. Two pilot SSFs, Filter 1 (F1) and
Filter 2 (F2), were operated simultaneously in the pipe gallery of the Winthrop, Maine water
treatment facility. The first microbial challenge took place in July of 2004 and was
followed by 8 more filter challenges with the most recent event taking place in March
2006. A final challenge is planned for July 2006. Each of the filter challenges
was 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 due
to the distance of the sampling site to the laboratory and also due to the amount of
samples collected from those two events. Both filters operated continuously for the
duration of the study for approximately 600 days and were only taken off-line for sand
sample collection or cleaning/scouring purposes. A low amount of ozone was
continuously 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 O<sub>3</sub> mg/L. Includes 23 references, tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 390 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 18 |
| Published : | 06/01/2006 |
