1
Q
What does disposal of solid wastes depend upon? (questions)
Give examples where appropriate
A
- properties and materials involved in the item:
- will it naturally degrade/compost?
- is it hazardous? (e.g. asbestos)
- is it radioactive? (e.g. gamma)
- is it toxic to plants and animals? - human physical factors
- population density
- land space
- transport costs
- attitudes
2
Q
How does the UK dispose of waste?
A
~70% into landfill
Guernsey: recycles ~75%
3
Q
What are landfill sites?
When would you use and why are there recyclables in there too?
A
licensed facilities for permanent waste disposal
- huge hole in ground
- leachates are collected
- methane may also be collected and burned
- may also involve land raising
Sometimes they are the only option, sometimes they are full of recyclables because people are unaware/lazy
4
Q
What are some of the sources for solid wastes?
A
- Mining and construction waste
- Domestic and commercial municipal waste
- Industrial waste
5
Q
Give characteristics of mining and construction wastes and give some examples
A
- large quantities produced
- most are non-hazardous but some can cause problems because they include particular hazardous materials
e.g.
- Mine overburden heaps - usually non-toxic
- Mine spoil heaps - may contain toxic metals
- Demolition waste - may contain hazardous materials such as asbestos
6
Q
What are the main categories of domestic and commercial municipal waste?
A
- packaging and containers
- paper
- domestic appliances
- organic materials: food and garden waste
- clothing and other textiles
- recyclables
7
Q
What are the waste management problems of domestic and commercial municipal waste?
A
- large quantities of waste are produced
- every household across the country produces waste which makes collection labour intensive and expensive
- the mix of waste varies throughout the year e.g. more garden waste during the summer
- many different types of waste are mixed together
- some people do not recycle
8
Q
What solid waste does industry produce?
A
- non-hazardous e.g. packaging, offcuts
- recyclable materials that can be processed into new objects e.g. metals, plastics, papers
- electronic waste: requires special handling due to many diff components and env impact
9
Q
What do the disposal problems with industrial waste depend on?
A
- properties of the specific waste involved
- amount produced
10
Q
What are the important properties of solid wastes influencing the choice of disposal method?
Give examples where appropriate
A
- degradability - how fast it breaks down
- conditions that affect degradation e.g. O2, pH, temp, bacterial presence
- flammability
- release of radioactivity
- toxicity
11
Q
What is the relationship between waste production and affluence?
A
RICHER = MORE WASTE. MORE AFLLUENT PEOPLE ARE MORE LIKELY TO:
- purchase more consumer goods
- purchase more trivia
- purchase disposable items
- throw away items rather than repair them
These activities also increase the wastes produced in the manufacture of goods and the mineral extraction required to make the items
12
Q
How may manufacturing and retail industries attempt to increase sales to the rich by using strategies that also increase wastes?
Give examples where appropriate
A
- PLANNED OBSOLESCENCE
- items designed to have a short lifespan e.g. made to be non-durable or wear out
- changing fashions mean that items become out-dated and are discarded, so the consumer can then ‘upgrade’ to the latest models - DISPOSABLE PRODUCTS
- items intended to have a limited usable life so they need to be replaced sooner e.g. disposable razors, cigarette lighters, ballpoint pens, packaging - OVER-PACKAGING
- items made to be more attractive with unnecessary packaging that is likely to be thrown away e.g. electronic devices (phones (the apple box?!), watches)
- packaging needed to keep things hygienic/sterile e.g. COVID tests, fruit and veg, medical equipment
13
Q
Give some negative effects of solid waste pollution
A
Some are deliberately/accidentally dumped into env:
- litter can harm wildlife that becomes caught in it or swallows it
- plastic wastes can degrade to become small particles that can choke marine organisms or release chemicals that may be endocrine disruptors
14
Q
What are some of the factors affecting solid waste disposal methods?
A
- pop density e.g. collection costs are higher where there are fewer people and the wastes are dispersed
- mass of waste produced per capita
- properties of the waste
- land availability
- availability of recycling technology
- degree of environmental awareness and willingness of people to recycle, reuse, repair
- regulatory framework and legislation
- household income
- waste processing costs for labour or machinery
15
Q
What are the methods for solid waste disposal?
A
Landfill
Spoil heaps
Incineration
Encapsulation and Vitrification
16
Q
Why is landfill the simplest option for solid waste disposal?
How did early landfill sites fail at life?
A
- requires little/no treatment of the waste itself
- early landfill sites were poorly managed, being used for mixed wastes with little attempt to prevent the escape of harmful fluids and gases
17
Q
What are the features of good landfill site management?
A
- quality assurance
- separation of different waste types of recording of their composition and locations
- polymer liner to prevent the release of leachate fluids
- regular covering with soil to reduce pest problems
- collection and treatment of leachate fluids
- collection of methane and its use as a fuel
- impermeable cap to prevent water entering once the site is complete: usually layers of clay and polymer
- deodorising spray to control odours
- dispersal of flammable materials rather than dumping large quantities in one place
- chemicals which may react with each other should not be dumped together
18
Q
Describe quality assurance at a landfill site
A
- all construction carried out on landfill sites is supervised and recorded by an independent consultant
- following construction, certification reports are produced by the consultant and issued to the Environment Agency for approval
19
Q
Describe the process of layering and covering a landfill site
A
Waste is placed in layers ~3m thick and compacted
At the end of each working da approximately 0.3m of clay or sand material is placed on top of the waste to:
- minimise the infiltration of rainwater
- isolate the waste from birds and vermin
- reduce odours
To prevent wastage and the formation of layers weakness within the waste, the daily cover is scraped off and reused each day
20
Q
What are landfill caps?
A
impermeable membranes used to cover the landfill and reduce infiltration of water
- less water = less leachate conc at bottom of landfill = lower potential for env damage
21
Q
Why are landfill gas management systems installed?
A
to prevent the build-up of gases within the landfill and to prevent migration of landfill gas through the underlying strata
22
Q
What are the two types of landfill gas management?
A
ACTIVE: systems involve the active extraction of the gas. This involves pumping air into and under the landfill to displace the methane. This gas can then be used as a fuel.
PASSIVE: systems compromise of wells with perforated tops to allow the gas to vent into the atmos.
23
Q
What are the advantages of landfill sites?
A
- cheap compared to other disposal methods
- land can be reused once site is full (but this may be limited e.g. for housing/agri)
- can be used to deal with large volumes of waste
24
Q
What are the disadvantages of landfill sites?
A
- toxic chems/leachate can be produced if poorly managed
- heavy metal ions can leach into the ground
- non-biodegradable plastics may not be broken down
- occupies large area
- habitat destruction, pollution etc
- organic matter decays anaerobically, releasing methane and CO2 = GW
- potential resource value is lost e.g. metals, glass, plastics
- transport delivering waste to the site and infr around it generate noise and congestion in the local area
25
Give an overall judgement of landfill sites
Not a very nice place
BUT
The negative effects can be minimised if:
- they are designed carefully with due consideration of geological and hydroecological conditions
- construction work is strictly controlled and regulated as well as supervised by independent bodies
- they are carefully managed throughout both operational life and aftercare period
26
What are the main problems with spoil heaps?
- large quantity of solids (usually non-toxic)
- can produce polluting leachate fluids
27
What industrial activities produce spoil?
Give examples where appropriate
- mining and quarrying e.g. coal, china clay, metal ores
- coal-fired power stations and incinerators produce ash
- iron blast furnaces produce slag
28
Why do spoil heaps need help in being managed?
- minimise env problems
- make site reuse easier after site closure
29
What possible problems need to be solved for the management of spoil heaps?
- stability
- drainage
- lack of nutrients
- pH
- contamination
- topography
- toxic leachates
- heavy metals
- flammable wastes
30
Why is stability an issue of spoil heaps and how can it be managed?
- landslips are a danger
- surface erosion can be reduced by establishing veg so the roots hold the soil together
- stability can be improved through compaction either by compacting the spoil heap as it is built up, or by constructing buildings on concrete rafts to reduce uneven settling
- this reduces the danger of subsidence
31
Why are heavy metals and contamination an issue of spoil heaps and how can they be managed?
HM
- HM a problem when they are mobile in the env, because they can be inhaled or ingested in food/water
- this can be prevented by disposing of them in solid form under alkaline conditions
- this means the metals should remain insoluble as their solubility is usually reduced with increasing pH
- to prevent dust particles, HM should be covered so that they cannot become airbourne
CONTAMINATION
- phytoremediation can be used where plants are used for the absorption and storage of pollutants such as HM, mercury
- petrochemical waste such as oil can be treated by bioremediation
- certain species of bacteria will digest the oil if appropriate conditions of temp, water supply and aeration are maintained
32
Why are toxic leachates an issue of spoil heaps and how can they be managed?
- should be collected and treated to prevent them entering water courses
- deeper layers of soil should be applied during restoration so that plant roots cannot reach the layer containing toxic materials
- this could bring toxins to the surface and cause their dispersal into the wider env
33
Why is lack of nutrients an issue of spoil heaps and how can it be managed?
Give examples where appropriate
- some spoil heaps have low levels of plant nutrients e.g. the sand left after china clay extraction or shale spoil from coal mining
- the addition of topsoil, sewage sludge and fertilisers are common techniques to improve the nutrient content and increase plant growth
34
What are some management techniques for spoil heaps?
- drainage ponds where leachate can run over lime and become less acidic (which would have increased the solubility/mobility of toxic/pollution metal ions)
- planting trees for root binding effect and reduced rain splash erosion
35
What is incineration? (solid pollution disposal)
destruction of wastes through high-temp combustion/oxidation
36
What are the by-products of incineration and what happens to them?
ASH: fly ash and bottom ash
- goes to landfill
HEAT: can be used as energy
37
What are the advantages of incineration as a solid waste disposal method?
- the volume of ash produced in much less than that of the original waste
- the heat produced may be used for district heating or the generation of electricity
- no sorting or complicated management is needed
- flammable materials like plastics and dirty paper and card can be separated and burnt in purpose-built power stations, or used for industrial heat such as cement manufacture. Large quantities of a single flammable waste can be used to produce a fuel for specific purposes
- fuels can be created
38
Give an example of specific fuels created through incineration of solid waste
Refuse-Derived Fuel (RDF) pellets of shredded compacted flammable municipal waste
Tyre-Derived Fuel (TDF) made from shredded vehicle tyres, sometimes mixed with coal, wood or other fuels
39
What are the disadvantages of incineration as a solid waste disposal method?
- the resource value of recyclable materials is lost
- toxic dioxins may be produced by reaction of organic wastes and chlorine
- the fuel used to maintain combustion of wet or non-flammable wastes is expensive
- the wastes may need to be separated to remove wet wastes, increasing processing costs
- the treatment of atmospheric pollutants in the effluent gases increases costs
40
What are the features of good domestic waste incinerators?
Give examples where appropriate
- recyclable wastes are removed before incineration
- wastes with a high water content are removed e.g. compostable waste
- the combustion temp is kept high and waste gases are cooled rapidly to reduce dioxin production
- the heat produced is harvested for use
- atmos pollution is controlled e.g. SO2, NOx, HCl, CO, smoke/PM10
- flammable organic wastes may be chemically broken down by incineration. The hydrocarbon component of the molecule will be converted to CO2 and H2O. These are not serious problems as they will be produced in small quantities, compared with other sources such as vehicle fuel
- some materials produced during the incineration process may need additional treatment e.g. Cl atoms from CFCs will react to create hydrogen chlorine. This dissolved to form hydrochloric acid and causes acid pollution. A water spray scrubber can be used to dissolve and remove it from gaseous emissions. The acid produced can then be neutralised by treating it with an alkali or crushed limestone
- heavy metals can be removed by scrubbing then stored in solid form at high pH, making them insoluble and less mobile
41
What is PM10?
What are the associated problems?
inhalable particulate matter with a diameter of 10 micrometers or less
- these particles can significantly affect air quality and pose health risks, particularly to the respiratory system and cardiovascular health
42
When might specialist waste disposals be needed?
Give examples of hazardous wastes that require specialist waste disposal
- if highly hazardous wastes are released into env they will cause serious pollution
- specialised storage or treatment techniques are likely to be required to avoid such pollution
e.g. asbestos, cyanide wastes
43
Give the impacts of asbestos that means it needs specialist waste disposal
- if it disintegrates and the fibres become inhaled, they cause irritation and can lead to asbestosis
- scar tissue produced in the lungs thickens the alveoli so gaseous exchange is slowed and breathing becomes more difficult
- asbestos also causes the specific cancer mesothelioma: cancer of the tissue that covers many internal organs, including the lungs. It can take decades to develop but it is not usually difficult to identify the cause as >80% is caused by asbestos
44
What are the sources/uses of asbestos?
- strengthening cement roof panels
- textured ceiling coverings
AS LONG AS IT REMAINS ENCAPSULATED AND INTACT IT IS NOT DANGEROUS
45
Outline the specialist disposal methods for asbestos
they need to be double wrapped in heavy-duty polythene bags in a specialised landfill site where the waste contents are recorded
46
What are cyanide compounds?
What are they used in/source of pollution?
triple bonds between C and N atoms, a fourth bond links the carbon atom to an element such as H or Na
USED IN:
- manu of paper, textiles and plastics
- electroplating, metal cleaing and gold extraction all use salts of cyanide
47
What are the negative effects of cyanide that require it to undergo specialist waste disposal?
very toxic enzyme inhibitors that may be inhaled or ingested
48
What is the specialist waste disposal technique for cyanide?
Incineration - C and N are separated and oxidised
The CO2 and NOx produced are a much smaller pollution problem BUT are still present
49
Why may encapsulation and vitrification be needed?
when some wastes are so hazardous they must be stored using a method where they become immobile and could not leak out in the future
50
What is encapsulation? (solid waste management)
hazardous wastes containing heavy metals such as arsenic mercury, nickel and chromium residues and intermediate level radioactive waste are mixed with a cement slurry which is poured into containers made of an impermeable and unreactive material
- the solid cement encapsulates the waste so it is immobilised
51
What is vitrification?
Explain the process
a specialist encapsulation technique used for the storage of high level radioactive waste that has been extracted from used nuclear fuel
- powdered radioactive waste is mixed with molten glass and poured into stainless steel containers which are then sealed
- the glass solidifies encapsulating the waste
- even if the glass were shattered, the waste would remain encapsulated in the fragments
- the steel containers are placed in cylindrical passages inside a concrete building
- the passages are ventilated to remove the heat generated within the waste
ENVIRONMENTAL SCIENCE 4. Pollution
flashcards
Decks in class (12)
# Cards
-
General and Properties64
-
Atmospheric Pollution79
-
Water Pollution55
-
Pesticide pollution52
-
Inorganic Nutrient Pollution - Eutrophication26
-
Acid Mine Drainage13
-
Monitoring Water Pollution17
-
Heavy Metal Pollution31
-
Solid Waste Pollution51
-
Noise Pollution40
-
Ionising Radiation Pollution83
-
Organic Nutrient Pollution27
