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Demonstrating Cryptosporidium Removal using spore monitoring at lime‐softening plants
Author(s) -
Cornwell David A.,
MaCphee Michael J.,
Brown Richard A.,
Via Steve H.
Publication year - 2003
Publication title -
journal ‐ american water works association
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.466
H-Index - 74
eISSN - 1551-8833
pISSN - 0003-150X
DOI - 10.1002/j.1551-8833.2003.tb10367.x
Subject(s) - spore , lime , softening , cryptosporidium , filtration (mathematics) , endospore , environmental science , biology , pulp and paper industry , environmental engineering , microbiology and biotechnology , mathematics , materials science , engineering , composite material , feces , paleontology , statistics
This study investigated the removal of Bacillus subtilis and other aerobic spore‐forming bacteria at four lime‐softening plants in the United States. Removal of aerobic spores has been shown through a compilation of literature to be a conservative indicator of Cryptosporidium removal during clarification and filtration. Results reported in this research demonstrated that lime softening involving two clarification stages and one filtration stage achieved 3.5‐ to 4.0‐log removal of aerobic spores during routine monitoring spanning periods of a year or more. More than half of the filtered water samples at two facilities were below detection limits, meaning that the actual log spore removal at these facilities may have been even higher than reported. Two facilities with presedimentation basins prior to lime softening were able to demonstrate an additional 0.5‐ to 1.0‐log spore removal. Given the conservatism of spore removal, it is anticipated that these plants can achieve at least the same amount of Cryptosporidium removal.