1. Both phosphorus and nitrogen compounds must be removed from sewage. Describe the basics of how those
    substances are removed at Padre Dam Water Recycling.
    • It is a biological nutrient removal approach. High levels of suspended solids, organic material,
    • nitrogen and phosphorus removal are achieved without the use of chemicals. NH3 converted to NO3
    • when the H is stripped off during aerobic then in anoxic bacteria get O from NO3 and bubble off N2—
    • denitrification, going down to 7 mg/l which needs to be reduced to 3mg/l.
    • Denitrification filters
    • reduces down to less than 2 mg/l.
    • Anaerobic to stress microorganism and they give off phosphorus, but don’t kill them (1 1/2 to 2
    • hours), then in aerobic they come back to life and take in more phosphorus than they lost. Goes from
    • 35 mg/l to 3 mg/l Biological Nutrient Removal (BNR).
    • Anaerobic—1 1/2 hours, organism sdie and release phosphorus at 5 mg/L.
    • Aerobic—come back to life and take up phosphorus at 8 mg/L
    • NH3 at 35 mg/L is dropped to 3 mg/L in going from NH3
    • to NO3
    • Anoxic uses NO3 oxygen as O2 source releasing N2 (denitrification).
  2. Primary stage
    1.grind large debris to small pieses to be pumped to recycling plant.

    2.heavy solids settle to the bottom of tank while lighter oils, greases and floatable debris rise to surface when waste water flows to primary clarifier.
  3. Secondary stage
    • 3. BNR-
    • Anaerobic zone
    • anoxic zone 1st
    • oxic zone
    • Anoxic zone(2nd)
    • Reaeration zone
    • micro Organisms feeding off pollutants while reducing nitro and phospherous.
    • 4.micro-organisms clumb together and settle to bottom and collected and a portion returns to BNR

  4. Tertiary
    • 5 flocculation/sedimentation: coagulant gathers suspended particles and percipitates remaining phospherous. particles sink to the bottom and removed.
    • 6.water seeps throught sand filterations where micro organisms remove nitro and reduce turbidity.
    • 7.Disenfect water in chlorine contact basin. water is chlorified for 90 min. water then meets title 22 (human contact)
  5. List three values of water to the biosphere.
    • 1. solvent
    • 2. heat conductor
    • 3. reactant in chemical reactions
    • three stages: solid,liquid, gas
  6. Describe the role of transpirational water loss in the water cycle.

    • transpiration adds water to the atmosphere which may then fall as precipitation and
    • continue the cycle of evaporation and condensation (falling as precipitation).

  7. What is the primary source of water for Southern California?
    • California Aqueduct System including water from the Los Angeles, California and Colorado Aqueducts, which
    • originate from the Colorado River, Owens Valley, Mono Basin and the Feather and Sacramento
    • Rivers plus the rivers of the western Sierra Nevada mountain range.
  8. List three strategies employed by the “hard-path” approach to energy use and contrast each of those with one strategy
    of the “soft-path.” (Energy-8)
    • Hard-path
    • a. Increase supply of energy to meet increasedEmphasize energy conservation to reduce total and per capita demands. b. Greatly increase the use of electricity. c. Depend primarily on nonrenewable energy resources.
    • Soft-path
    • Emphasize energy conservation to reduce to
    • avoid increases in total and per capita energy use
    • Use electricity only for appropriate
    • energy needs.
    • Increase the use of renewable energy
    • sources.
Card Set
quiz 4