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Lecture 10

ENSC 2001 Lecture Notes - Lecture 10: Low-Level Waste, Nuclear Fission Product, Disinfectant

Environmental Science
Course Code
ENSC 2001
Quentin Gall

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Modern trend: Integrated Waste Management (IWM)
Emerged in 1980s
Including reduction, recycling, reuse, composting, landfill, and incineration
Three Rs approach: reduction, recycle, reuse (reducing urban refuse by 50%)
More notable success with recycling, but less with reducing waste production
95% of environment damage has already occurred before recycling
Material Management
New goal: zero production of waste
Combining sustainable use of materials with resources conservation
Industrial ecosystem: producing natural urban and industrial ecosystem through material management,
waste from one part of the system as resource for another part
Liquid Waste
Sewage (wastewater + contained solid waste): largest volume of liquid waste
Waste water treatment
o Septic tank disposal
Common in rural area.
Water flow in septic tank, solids sink down to the bottom of the tank and decomposed by bacteria. Then
water flow in drain field (which is unsaturated and well oxidized for maximum efficiency) and the
filtered water can be used for agriculture
o Waste treatment plants
Used in large urban center.
Existing wastewater treatment generally has two or three stages:
1) Primary treatment, remove 30% to 40% of the pollutants. It includes:
Screening: remove the grit composed of sand ,stones, and other large particles
Sedimentation: remove remaining particulate matter (mostly organic) and form sludge.
2) Secondary treatment, activated sludge method, clean up 90% of the waste water. It includes:
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