1. Solid Wastes

2. Salvaging and Recycling
Properties
Sources
Control
composition relating to bulk and mobility
Degradability
Flammability
Radioactivity
Toxicity
Mining and construction
Municipal (domestic and commercial)
Industrial
Agricultural
The link between waste and affluence!
Built-in obsolescence
Convenience
Disposable products
Over packaging
Treatment Methods
Solid Waste
The economic and environmental advantages and disadvantages of disposal by:
• landfill and land raising on derelict land/exhausted quarries
• incineration and pyrolysis of household and industrial wastes
• encapsulation/vitrification of high-level radioactive waste
Salvaging and recycling
The reduction of resource exhaustion and waste production
Salvaging and Recycling
efficient use of resources and extraction efficiency
• production loops eg trimmings from plastic mouldings/paper
cutting
Resource substitution
Re-use and recycling of resource materials to include:
- composting
- The scientific/technological, social and economic problems of
recycling compared with use of virgin materials with specific
reference to aluminium: waste losses, eg litter, mixed alloys,
- transport, labour costs, separation, identification, energy costs,
- need for public co-operation

3. The Essay Style Question
Discuss the advantages and disadvantages of the methods that can be used to dispose of solid wastes (20)
taken from the Enviro Text Book p 216

4. Sources Mining, quarrying and construction
Ash from coal-fired power stations
Municipal waste of variable composition
Industrial waste
Agricultural wastes e.g. carcasses

5. Properties
Disposal method depends upon properties e.g. Will it degrade/compost?
Vegetable matter, paper, cardboard and some textiles will biodegrade.
Is it hazardous? e.g. asbestos
Is it radioactive? If so, what type of radioactivity is being emitted?
Is it toxic to plants or animals?
But also factors such as
Land availability (e.g. for landfill
Availability of recycling facilities
Per capita waste production
Transport costs

6. Solid waste treatment 1. Landfill 2. Incineration
Essentially a huge hole in the ground
Leachates are collected
Methane may also be collected and burned
May also involve land raising
2. Incineration
High temperature incineration
May involve pyrolysis
3. Encapsulation and vitrification of HL radioactive waste
HL liquid wastes are concentrated by evaporation, then stored in double-walled stainless steel tanks inside thick concrete walls awaiting vitrification – converted into a borosilicate glass within steel canisters.

7. Advantages and disadvantages
Method
Advantages
Disadvantages
Landfill / land raising
Provides a use for waste land/ derelict land
Land can be used after landfill sealed
Air pollution – CO2, CH4
Leachates
Traffic
Litter/seagulls
Incineration
Reduces volume
Can provide district heating
High capital cost
Air pollution – particulates
Ash toxic and still requires disposal
Encapsulation & vitrification
Long-term, safe storage
Expensive
Material remains radioactive for thousands of years

8. Salvaging and recycling
Defra (2008) reported that household recycling has increased for the third year running
Total waste sent to landfill has declined
Besides reducing waste, salvaging and recycling saves money and natural resources
e.g. collecting, remelting and remoulding metal off-cuts will reduce:
total amount of metal needed
total volume of ore needing mining
Production loop: a recycling process where an industry uses the wastes produced during the manufacturing process itself.
Resource substitution: the use of a more abundant material instead of a less abundant one e.g. using plastic instead of metal

9. Compost
Produced from waste plant material e.g. grass cuttings, fallen leaves and vegetable waste by the action of aerobic microorganisms
Slatted container to allow air to enter
Waste plant material
Consists of partly decomposed organic material that is rich in minerals e.g. nitrates
Rate of production of compost depends on factors such as:
temperature
moisture content
aeration

10. Compost
The respiration of the microorganisms generates heat which kills weed seeds and some plant pathogens
Why does the compost temperature drop in weeks 9-14?
reduced food available for the microorganisms
more competition so growth rate reduced
less oxygen becomes available
change in water / pH slows growth 14
Compost heap
External air 1 2 3 4 5 6 7 8 9 10 11 12 13
Time/weeks
-10 20 30 40 50
Temp. oC

11. Landfill
The government has set targets under the Landfill Directive for LAs to recycle an increasing proportion of domestic waste
Domestic waste production 2007
Material
Glass
Plastics
Paper and card
Scrap metal
Compost
Total
Thousand Tonnes
470 90
1100
420
1320
3400
Control
Volume of waste tends to increase with affluence
Increased purchase of :
All goods  packaging etc
Disposable goods
Goods with built-in obsolescence

12. Aluminium recycling
Aluminium is widely used in cans and aircraft etc as it is light and strong
Social, economic and environmental consequences of the production of aluminium from bauxite ore in Jamaica
Villagers relocated
Forests/ crops cleared
Topsoil removed
Bauxite recovered using opencast mines
Bauxite dissolved in sodium hydroxide using high temperature and pressure
Alumina precipitated out
Alumina electrolysed to produce aluminium
Contaminated mud is dumped off site

13. Aluminium recycling Recycling coke cans helps avoid all this! ..and:
saves fossil fuels
reduces air & water pollution
reduces water use
% reduction in
Recycled Materials
Aluminium
Glass
Paper
Steel
Energy usage
90-97
4-32
23-74
47-74
Air pollution 95 20 74 85
Water pollution 97 - 35 76
Mining wastes 80
Water usage 50 58 40
Problems
Public motivation
Aluminium often used in alloys-separating the metals is expensive
Collection and transport costs and transport pollution
Labour costs –collection is often labour-intensive
Unsorted wastes may be difficult/expensive to recycle

14. Aluminium recycling
Recycling provides significant proportions of the United Kingdom's metals consumption and saves money
The Recycling Scorecard
There are other benefits. For example, using recycled steel instead of virgin ore to make new steel leads to typical reductions of:
86% in air pollution - 40% in water use - 76% in water pollution
The world metal recycling industry employs 1.5 m people & supplies > 550 mt of secondary materials annually to steelworks and foundries

15. More on landfill

16. Landfill Sites
There are 4000 operational and 4000 closed landfill sites in the UK
Many old landfills are poorly designed and major environmental hazard. They are not designed for 50, 100 or 1000 years into the future
Two types of landfill in the UK are
leach and disperse (old sites)
containment and treatment (new sites)

17. What Happens in a Landfill Site?
Rain water dissolves & reacts chemically & biologically with waste
Leachate
Landfill Gas

18. Leachate toxins kill aquatic life eutrophication in rivers
precipitates iron
kills vegetation
pathogens/bacteria
non-hazardous materials can decompose into hazardous products
serious groundwater pollution

19. Landfill Gas
methane

20. Landfill Gas
Loscoe, Derbyshire

21. Methane escape from the Loscoe Landfill caused an
Landfill Gas
Methane escape from the Loscoe Landfill caused an
explosion in 51 Clark Avenue near the site as gas escaped via highly permeable sandstones
Loscoe, Derbyshire

22. Possible Routes by Which Landfill Gas Can Migrate from a Site
Desiccation cracks in soil
Highly permeable strata
Gas vents
Tree roots
Caves & natural cavities
Underground services e.g. sewer pipes
Mine shafts
Highly permeable strata
Fissured & fractured strata

23. Landfill Site Selection
Geology of Area
Porosity & permeability of rock
Resistance to weathering
Impermeable to contain leachate
Joints & fracture systems in rock
Dip of rock strata
Free from disturbance (tectonic/subsidence)
Hydrology of Area
Rate of groundwater flow
Gradient of groundwater flow
Reduce groundwater contamination
Depth to water table
Fluctuations of groundwater
Topography of Area
A site capable of retaining waste
Existing hole or steep sided quarry

25. Site Preparation
top layer is about one foot of compacted soil to protect the entire liner system from the waste.
very tough fabric, called a geotextile fabric, to protect the pipes.
one-foot layer of gravel with pipes running through it. The leachate collects in these pipes and is pumped out of the landfill and filtered.
strong, flexible, very thick plastic, called high density polyethylene (HDPE) known as a geomembrane.
two feet of compacted clay
Modern Landfill Site
Each evening, large trucks roll over the landfill to crush the day's rubbish and then cover it with 15cm of soil so the waste doesn't smell or attract flies and rats.
When an area of the landfill is completely full, it is capped with clay and soil. This final landfill cover helps keep rainwater out of the waste and reduces the amount of leachate that forms.

26. Site Management & Monitoring
monitoring groundwater for chloride & ammonia in plumes
monitoring unsaturated zone for gases
venting of methane gas by boreholes
porous pipes to transfer leachate into sumps for collection & removal

28. Low level industrial development
Site Restoration
Uses
Parkland
Recreation
Open spaces
Greenbelt
Low level industrial development
Housing

29. Site Restoration
Trumps Farm is a former sand pit which was used by Surrey County Council for the disposal of household waste from the early 1980s until its closure in 1998.
The overall objective of the works is to reinstate the landfill to pasture and meadow, to a landscape typical of the area and create a variety of wildlife habitats.

30. Site Restoration Problems
Methane gas hazard – leakage through permeable rocks
Ground instability on completion - subsidence
Groundwater pollution
Landfill site needs to remain accessible for over 25 years to manage & monitor

31. Non-hazardous Waste Disposal Landfill Sites
Factors Affecting Site Selection
Site Preparation
Landfill Sites
Problems after site is restored
Site Management & Monitoring
What happens in a landfill site
Problems of Leachate
Problems of Landfill Gas
Pollutants

32. In UK stored for 50 years to cool prior to solidification and storage
Radioactive Waste
Nuclear presents a special problem
because of its long half life, it remains
radioactive for thousands of years.
In UK stored for 50 years to cool prior to solidification and storage
Then it needs to be isolated for 250, 000 years

34. 2. What specific problems do they cause?
Radioactive Waste
1. What is the difference between high level and low level radioactive waste (how are they caused)?
2. What specific problems do they cause?
3. What factors need to be taken in to account with high level radioactive waste disposal?
4. What are the options for high level radioactive waste disposal? (give examples)
5. How is low level radioactive waste disposed?
6. What are the geological factors that need to be taken into account when building an underground repository?

35. Hand outs to print for your file on next 2 slides

37. Possible Routes by Which Landfill Gas Can Migrate from a Site