In recent years, a variety of viral, bacterial, and protozoan
agents have been implicated as waterborne agents that pose
a risk to human health. Although Cryptosporidium and Giardia
have been the focus of concern (and most regulatory action),
emerging waterborne pathogens include Escherichia coliO157:H7
and Aeromonas hydrophila. This research was undertaken to
determine whether these and other pathogens are effectively
removed by current surface water treatment technology.
Cryptosporidium parvumoocysts, Encephalitozoon intestinalis
spores, enteropathogenic E. coliO157:H7, A. hydrophila,and
bacteriophage MS2 were subjected to pilot-scale conventional
treatment with alum coagulation, flocculation, sedimentation, and
filtration. The study tested the effects of filter run time, alternative
loading rates, alternative filter media, and pH on pathogen
removal. Results indicated that turbidity breakthrough at the end
of a filter run was accompanied by the breakthrough of all
pathogens tested, with a more rapid breakthrough of A.
hydrophilaand E. coliO157:H7. Filtration rate and alternative
filter media configurations had no apparent effect on pathogen
removal. A pretreatment and filtration pH of 5.7 achieved better
pathogen removal for C. parvumoocysts through sand filtration
and for E. coliO157:H7 and bacteriophage MS2 through dualmedia
and trimedia filtration.
Although conventional treatment offers an effective barrier
against some microbial threats, it is a poor defense against others.
Compared with Cryptosporidium, certain pathogens reach
filter breakthrough faster and are more poorly removed by conventional
means. A multiple-treatment barrier approach may provide
surface water suppliers with a better safeguard against emerging
waterborne pathogens. Includes 21 references, table, figures.
| Edition : | Vol. 95 - No. 12 |
| File Size : | 1
file
, 350 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 10 |
| Published : | 12/01/2003 |
