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4. Drinking Water Quality and Treatment
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3 categories of waterborne pathogens regulated in the U.S.
virus
bacteria
protozoa
point and nonpoint sources
point - pipe, localized source
nonpoint - runoff, surface waters, urban streets, homes, cropland
septic tanks
purpose is to separate solids and scum from waste water
provide some degree of anaerobic digestion of organic matter
deliver the waste water to the subsurface
must be maintained to prevent from going into neighbor's drinking water
conventional vs. in-line treatment
in-line treatment only missing 1 step -floc/sed. step
flocculation
turbulence provided by gentle stirring to keep flocs from settling and form bigger mass of neutral particles
3 organisms that must be removed from all surface water systems that serve more than 10,000 people
Cryptosporidium
Giardia lamblia
viruses
chlorine residual
chlorine dose - chlorine demand
why is it harder to disinfect protozoa?
cysts form thick cell wall
John Snow
father of public health/epidemiology
knew illnesses were water borne when it was commonly thought they were air borne
analyzed deaths from cholera in certain area were from water company getting water upstream of sewage outlets
had broad street pump closed which had broken brickwork between pump and cesspool to stop cholera outbreak
Legionella
outbreak of severe pneumona caused by a gram-negative rod, spread through the air conditioning ducts
transmitted by inhalation of infectious aerosols
facultative intracellular parasite - can multiply in alveolar macrophages and monocytes and in nature in free-living ameobae
Author
cornpops
ID
94750
Card Set
4. Drinking Water Quality and Treatment
Description
public health microbiology midterm 2 lecture 4
Updated
7/26/2011, 8:57:12 AM
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