4. Drinking Water Quality and Treatment

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4. Drinking Water Quality and Treatment
2011-07-26 04:57:12
PH162A midterm2

public health microbiology midterm 2 lecture 4
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  1. 3 categories of waterborne pathogens regulated in the U.S.
    • virus
    • bacteria
    • protozoa
  2. point and nonpoint sources
    point - pipe, localized source

    nonpoint - runoff, surface waters, urban streets, homes, cropland
  3. 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
  4. conventional vs. in-line treatment
    in-line treatment only missing 1 step -floc/sed. step
  5. flocculation
    turbulence provided by gentle stirring to keep flocs from settling and form bigger mass of neutral particles
  6. 3 organisms that must be removed from all surface water systems that serve more than 10,000 people
    • Cryptosporidium
    • Giardia lamblia
    • viruses
  7. chlorine residual
    chlorine dose - chlorine demand
  8. why is it harder to disinfect protozoa?
    cysts form thick cell wall
  9. 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
  10. 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