AWWA JAW59120

In recent years, a variety of viral, bacterial, and protozoanagents have been implicated as waterborne agents that posea risk to human health. Although Cryptosporidium and Giardiahave been the focus of concern (and most regulatory action),emerging waterborne pathogens include Escherichia coliO157:H7and Aeromonas hydrophila. This research was undertaken todetermine whether these and other pathogens are effectivelyremoved by current surface water treatment technology.Cryptosporidium parvumoocysts, Encephalitozoon intestinalisspores, enteropathogenic E. coliO157:H7, A. hydrophila,andbacteriophage MS2 were subjected to pilot-scale conventionaltreatment with alum coagulation, flocculation, sedimentation, andfiltration. The study tested the effects of filter run time, alternativeloading rates, alternative filter media, and pH on pathogenremoval. Results indicated that turbidity breakthrough at the endof a filter run was accompanied by the breakthrough of allpathogens tested, with a more rapid breakthrough of A.hydrophilaand E. coliO157:H7. Filtration rate and alternativefilter media configurations had no apparent effect on pathogenremoval. A pretreatment and filtration pH of 5.7 achieved betterpathogen removal for C. parvumoocysts through sand filtrationand for E. coliO157:H7 and bacteriophage MS2 through dualmediaand trimedia filtration.Although conventional treatment offers an effective barrieragainst some microbial threats, it is a poor defense against others.Compared with Cryptosporidium, certain pathogens reachfilter breakthrough faster and are more poorly removed by conventionalmeans. A multiple-treatment barrier approach may providesurface water suppliers with a better safeguard against emergingwaterborne pathogens. Includes 21 references, table, figures.

Product Details

Edition:

Vol. 95 - No. 12

Published:

12/01/2003

Number of Pages:

10

File Size:

1 file , 350 KB