Waste Water Treatment and Water Purification

The flashcards below were created by user cornpops on FreezingBlue Flashcards.

  1. wastewater
    liquid effluent derived from domestic sewage or industrial sources
  2. sewage
    liquid effluent contaminated with human or animal fecal materials
  3. domestic wastewater
    • sewage
    • "gray water"
    • waste water from food processing
  4. industrial wastewater
    • effluent from petrochemical, pesticide, food, dairy, plastics, pharmaceutical, and metallurgical industries
    • may contain toxic substances
  5. goal of wastewater treatment facility
    to reduce organic and inorganic materials to a level that no longer supports microbial growth and to eliminate other potentially toxic materials
  6. *biochemical oxygen demand (BOD)
    • relative amount of dissolved oxygen consumed by microorganisms to completely oxidize all organic and inorganic matter in a waste sample
    • indicator of water purity

    • determined by:
    • taking a sample of water
    • aerating it well
    • placing in a sealed bottle
    • determining the residual oxygen in the water at the end of the incubation

    low BOD indicates unable to support bacterial growth
  7. primary wastewater treatment
    • physical separations
    • grates and screens that remove large objects
    • effluent is left to settle, suspended solids sediment
  8. secondary wastewater treatment
    • anoxic digestion of sludge in sludge digesters/bioreactors - converts insoluble organic material
    • oxidation - activated sludge and trickling filter methods most common

    eluent is typically chlorinated. UV and ozone also used
  9. *Other than treated water, what are the final products of wastewater treatment?
    • digested sludge
    • methane
    • CO2
  10. aerobic secondary wastewater treatment
    • trickling filter method:
    • wastewater sprayed over bed of crushed rocks
    • biofilm on rocks results in mineralization of organic matter

    • activated sludge process:
    • wastewater is mixed and aerated in a large tank
    • slime forming bacteria grow and form flocs
    • other organisms attach to flocs
    • effluent pumped into clarifier, flocs settle
  11. tertiary wastewater treatment
    • expensive, not common
    • employs precipitation, filtration and chlorination similar to drinking water purification
    • greatly reduces levels of inorganic nutrients and is unable to support extensive microbial growth
  12. *drinking water purification
    • 1. sedimentation basin
    • anionic polymers
    • aluminum sulfate
    • chlorine
    • 2. clarifier/coagulation basin
    • aggregates form (flocculation)
    • 3. filtration
    • thick layers of sand and ionic filtration media
    • 4. disinfection
    • chlorine

    • chloramine - used for long distances (stable, not volatile)
    • UV - good for short distances
  13. coliforms
    • indicator organisms
    • usually associated with intestinal tract
    • aerobic and facultatively aerobic
    • gram-negative
    • nonspore-forming
    • rod-shaped
    • ferment lactose with gas formation
    • most are enteric
  14. the coliform test
    • water passed through a sterile membrane
    • filter is placed on the surface of a plate of EMB
    • coliform colonies are counted
    • calculate presence in water
    • test must pass drinking water standards
  15. *How is EMB a selective medium?
    • the dye inhibits growth of most gram-positive bacteria
    • selecting for presence of gram-negative bacteria
  16. *How is EMB a differential medium?
    • lactose-fermenting bacteria acidify the medium turning Eosin (a pH sensitive) dye black
    • colonies of lactose nonfermenters are translucent
  17. *Why is the coliform test useful?
    coliforms are enteric and indicates fecal contamination of the water source
  18. How can the coliform test fail in determining water safety/quality?
    • doesn't see viruses or protists
    • some pathogens are not coliforms
    • some pathogens are not culturable
    • cells may be slow growing
  19. IDEXX Coliliert water quality test (proprietary)
    • a defined substrate test
    • identifies coliforms and specifically E.coli based on actions on specific substrates with one medium
    • can cause media to change color or fluoresce under UV
Card Set
Waste Water Treatment and Water Purification
general microbiology midterm 3
Show Answers