E8 Waste
Guiya, China 70% 20 to 50 million tons
Methods of waste disposal:
Landfill sites, incineration, large scale composting, recycling
and burial of radioactive wastes
Landfill vs incineration
Landfill – more waste, less land, ugly (Adam’s mine)
- transportation cost (landfill not usually in city)
- source of water and soil pollution (line landfill), anaerobic decomposition
(CH4, H2S, NH3), medical waste sterilized
Incineration – makes less waste volume, slag produced can be used in roads
- transportation cost (inciner. not in city), uses energy in running incinerator
plant
- pollution from burning plastics (dioxins), destroys microorganisms that cause
disease
Radioactive waste
Radioactivity isotopes to undergo rxns involving nuclear change
Alpha particles  positive helium nuclei (2p + 2n), stopped by clothing, skin
Beta particles  electrons, 100 times penetrating power of alpha, stopped by
1mm thick aluminium foil
Gamma particles  high energy electromagnetic radiation, 100 times penetrating
power of beta, stopped by 10 cm of lead
t1/2 (half life) is the time required for one-half of the amount of radioactive
material to decay; Pu – 239 t1/2 is 24,000 years.
Radioactive waste storage and disposal depends on the amount of activity it produces and
the half-life of the raqdioisotopes involved
Type of radioactive waste
Low level waste (90% volume of nuclear waste, only about 1% of the radioactivity
 contain small amounts of radioisotopes producing low activity alpha + beta
particles of short half lives (low radioactivity)
 includes clothes, gloves, paper, plastic, from nuclear plants, hospitals,
research facilities
 decreases to background radiation within 500 years, 90% 100 years
 low level reduced material, along with intermediate stored in steel drums in
concrete vaults below ground. (Love canal, Canada storage)
 low level incineration allowed with controls, landfills + ocean dumping
banned
 Cs and Sr products of fission are low level nuclear waste and can be removed
by the use of ion exchange resin
Medium or intermediate level waste
 contain greater amounts of radioisotopes with intermediate activity and
intermediate half-lives
 nuclear reactor parts and processing nuclear fuel
High level waste (occupies a small volume of nuclear waste but contains most of the
radioactivity
 large amounts of high activity (beta and gamma rays) with long half lives
remain radioactive for long periods
 spent fuel rods and processing of spent fuel
 small volume of all nuclear waste, most of the radioactivity
 temporarily stored in pools of water to absorb heat from radioactivity
 one method for storage is to make liquid waste into glass followed by burial
deep underground in geologically stable, non leaching environments (i.e.
granite), meant to be non-corrosive + kept intact for hundreds of thousands of
years.
Recycling Process
Metals  separate ferrous (magnetic) and non-ferrous metals
 non-ferrous light metals separated by flotation
Glass  separated by colour, glass for food + drink, recyclable
 mirrors, window pains, light bulbs, not recycled
 ‘cullet’ crushed glass magnet to remove metal, vacuum to remove paper +
plastic
 cullet mixed with sand, limestone, soda ash and melted at 1200 C
 glass is moulded or blown into new products
Plastics  large variation in chemical composition difficult to separate
 numbering system facilitates separation
 some not able to be recycled, plastics for packaging bakery and food products
 polyethylene terephthalate (PET) + high density polyethylene (HPE) thicker
containers (juice) can be recycled
Paper  separate out paper coated with wax or plastic (not usuable)
 paper chopped and mixed with water, clay, CaO, CaCO3
 makes paper in fibres and makes pulp, spinning pulp removes heavy objects
(staples)
 ink is removed water, surfactant chemicals remove ink and glue, colours also
removed
 fresh pulp added, needs to treated to remove lignin (if not yellow (newspaper)
 hydrogen peroxide or chlorine dioxide to bleach paper to product white
Benefits
Metals  conserves natural resources, decreases energy, landfill +water use(Al 95%less)
 Al + steel can be recycled over + over (most recycled)
Glass  conserves raw material + mining waste + land fill
 1/3 less energy then virgin glass
 cullet can be used in highway construction
 recycled over and over
Plastics  conserves landfill + reduces incineration + less raw materials (petrochemical)
+ less energy + less water
 recycled PET used in pillows, jackets, automobile seats, insulation
Paper  less water + energy + natural resources + less landfill
 less greenhouse gases
 can’t be recycled over and over cause fibre loses strength