E8: Waste (UNMODIFIED)

Open DumpingPros:Simple, inexpensive, convenientCons: Health hazards - rodents and insects proliferate Releases pollutants to the air and groundwater Unsightly

Landfill SitesWhat is it? Burial of waste in a way that isolates waste from groundwater in aquifers and prevents contact with water Leaching of chemicals is prevented by impermeable clay liners/ synthetic materials Pros: Efficient method to handle large volumes of solid waste Filled land can be covered and use for other purposes Cons: Large area needed Transportation costs Source of air and groundwater pollutants Anaerobic conditions to promote formation of methane (GHG) and H2S (toxic) Non-biodegradable plastics will accumulate

Incineration:Pros: Efficiently reduces volume of waste (organic matter is converted to gases) Heat produced can be used to maintain the high temperatures needed for incineration High heat destroys disease causing microorganisms "Slag" (the product) can be used in roads and buildings for construction Cons: Requires energy to run (although the heat released can reduce energy costs) Releases large volumes of CO2 Burning of plastics releases dioxins Incomplete combustion of plastics releases CO Expensive to build facilities 

How it helps:Reduce the use of raw materials, energy costs, level of pollutants, land requirements for waste disposalChallenges: Separation of materials, purification of materials are difficult Recycled materials tend to be of lower quality

Met

Metal RecyclingProcess: Collect Metal Cutting Separation using magnets (into ferrous and non-ferrous metals (e.g. aluminum and higher density metals) via flotations) Melted and reused in alloys Pros: Conserves natural resources Reduces use of energy, water and landfill (95% reduction in energy costs when Al is recycled, 50% for steel) Less energy used in mining and metal refining = fewer GHG Aluminum is one of the most successfully recycled metals (100% of the aluminum in a recycled can ends up in another within 60 days)

Gl

Glass 

Glass RecyclingProcess: Sorted by color Washed Crushed (Cullet) Ferrous materials removed by magnets Plastic and paper removed by vacuum Melted Moulded into new products Pros: Conserves natural resources (sandstone and limestone) Uses 1/3 less energy than producing virgin glass Uses 1/2 the water of virgin glass production Recycled glass can be reused

{a[er

Paper RecyclingProcess: Sorted by type Cleaning to remove ink and additives Chopped and added to water (= slurry) Spinning to form pulp Bleaching with peroxides (for white paper) Pros: Uses 1'2 energy and water used to produce virgin paper Preserves forests by reducing number of trees cut down (therefore reduction of GHG and habitat destruction) Extends life of landfill sites Paper Recycling VS Composting Paper may be composted (aerobic conditions) Paper will not degrade in landfill sites (anaerobic conditions)

Plastic Recyling Not all plastics can be effectively recycled (not for low density plastics) Types = Ranked (1 - 3 PETE = recyclable) e.g. PET = recyclable Method 1: Grinding Method Sieving Optical sorting Manual checking Grinding Washing Decontamination Method 2: Thermal Process Heated in absence of air (pyrolysis) Polymers break into monomers Fractional distillation separates monomers Repolymerzation: monomers used to make new plastic Pros: Conserves crude oil Saves landfill space uses less energy and water Recycled PET has many uses Cons:Sorting of plastics is costly and time consuming

Radioactive Waste CategoriesLow Level Radioactive Waste: Radioisotopes used in research labs and in medical treatments Low "activity" (number of nuclei that decay per unit time) High volume Short half life Sources: clothing, gloves, paper/ plastics from hospitals, research labs, etc. High Level of Radioactive Waste Spent fuel rods from nuclear reactors High "activity" Low volume Long half-life Sources: Spent fuel rods, processing of nuclear fuel

Low Level Radioactive Waste (High Volume) Stored in "cooling ponds" of water until decay to safe levels (isotopes are then removed by ion-exchange columns before discharge) Storage in steel containers inside concrete lined vaults

High Level Radioactive Waste (Low Volume) Reprocessing of spent fuel (96% of uranium = recovered for re-use; 1% plutonium = recovered; 3% high level liquid radioactive waste) First Step: cooling in deep pools of water containing neutron absorbers (e.g. borons) to stop fission chain reactions Vitrification (Waste mixed with molten glass and poured into tubes to solidify) Storage (Buried deep in the earth in impervious granite rock/ unused mines (MUST be remote and geologically stable)) Concern - Leakage into groundwater

Waste Disposal Methods

Recycling

Radioactive Waste

Radioactive Waste Storage and Disposal