Appl Environ Microbiol. 1985 May; 49(5): 1191–1196.
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Effect of an activated sludge wastewater treatment plant on ambient air densities of aerosols
containing bacteria and viruses.

K F Fannin, S C Vana, and W Jakubowski

(In general, the densities of microorganism-containing aerosols were higher at
night than during the day.)

This article has been cited by other articles in PMC.

Bacteria- and virus-containing aerosols were studied during the late summer and fall seasons
in a midwestern suburb of the United States before and during the start-up and operation of an
unenclosed activated sludge wastewater treatment plant. The study showed that the air in this
suburban area contained low-level densities of indicator microorganisms. After the plant began
operating, the densities of total aerobic bacteria-containing particles, standard plate count
bacteria, total coliforms, fecal coliforms, fecal streptococci, and coliphages increased
significantly in the air within the perimeter of the plant. Before plant operations, bacteria were
detected from five genera, Klebsiella, Enterobacter, Serratia, Salmonella, and Aeromonas.
During plant operations, the number of genera identified increased to 11. In addition to those
genera found before plant operations, Escherichia, Providencia, Citrobacter, Acinetobacter,
Pasteurella, and Proteus, were also identified. Enteric viruses were detected in low densities
from the air emissions of this plant. Only standard plate count bacteria remained at
significantly higher than base-line densities beyond 250 m downwind from the center of the
aeration tanks. Fecal streptococci and coliphages appeared to be more stable in aerosols
than the other indicator microorganisms studied. In general, the densities of microorganism-
containing aerosols were higher at night than during the day. The techniques used in this
study may be employed to establish microorganism-containing aerosol exposure during
epidemiological investigations.