Waste Management Flashcards
Overview
Landfilling and thermal treatment of waste incineration) are the most common methods of waste disposal in high-income countries. Most low-
and lower middle-income countries dispose of their waste in open dumps. Some of this disposal may
be unregulated. This means it is not controlled or supervised by regulation of law. Solid waste that is not properly collected and disposed of can be a
breeding ground for insects, vermin and scavenging animals, and can thus pass on air- and water-borne
diseases.
A survey conducted by UN-Habitat in 2009 found that in areas where waste is not collected frequently, the incidence of diarrhea is twice as high
and acute respiratory infections six times higher than in areas where collection is frequent. Environmental
threats include contamination of groundwater and surface water by leachate, as well as air pollution from
burning of waste that is not properly collected and disposed of.
Recycling and recovery 1
Resource recovery is the selective extraction of disposed materials for a specific next use, such as
recycling, composting or energy generation.
Recycling iscarried out when materials from which the items are made can be reprocessed into new products.
In recent years, the global market for recyclables has increased significantly. The world market for post-consumer
scrap metal is estimated at 400 million tonnes annually and around 175 million tonnes annually for paper
and cardboard (UN-Habitat 2009). This represents a global value of at least $30 billion per year. Recycling,
particularly in low- and middle-income countries, occurs through an active, although usually informal,
sector. Estimates suggest that about 1 per cent of the urban population - at least 15 million people - survive
by salvaging recyclables from waste.
Recycling and recovery 2
Manufacturing new products using recycled materials
can save significant energy. For example, producing
aluminum from recycled aluminium requires 95 per cent less energy than producing it from virgin materials.
Urban mining is the name given to the process of recovering compounds and elements from products, buildings and waste which would otherwise be left to decompose in landfills. By collecting and salvaging
valuable components to be reused and recycled, there is
a greater chance of reducing landfill waste.
The key advantages of recycling and recovery are reduced quantities of disposed waste and the
return of materials to the economy.
However, there are some negative environmental issues. Notably,
energy may be required for the operation of material recovery from waste and this leads to greenhouse
gas emissions. Informal recycling by waste pickers will have little greenhouse gas emissions, except for
processing the materials for sale or reuse, which can
be relatively high if improperly burned (for example,
metal recovery from e-waste).
Trade
Waste may be moved between and within countries.
The global waste trade is the international trade
of waste between countries for further treatment,
disposal, or recycling. Toxic or hazardous wastes are
often exported from high to low-income countries
as seen in the example of e-waste in the textbox.
However, these countries often do not have safe
recycling processes or facilities and hazardous wastes
are not properly disposed of or treated, leading to
contamination of the surrounding environment.
International laws such as the Basel Convention have
been introduced to prevent transboundary movement
of hazardous waste but evidence suggests it still
happens.
Incineration
Incineration of waste (with energy recovery) can
reduce the volume of disposed waste by up to 90
per cent. General waste can be safely burned at high
temperatures and under carefully controlled conditions
to produce electricity and heat. This is referred to as
energy from waste and an increasing number of cities
are processing their waste in this way. Incineration
without energy recovery is still common but it is not
a preferred option due to costs and pollution. The
open-burning of waste, which is common in poorer
countries, is particularly discouraged due to severe air
pollution associated with low temperature combustion.
Burial
Burial is the placement of waste in man-made or
natural excavations, such as pits or landfills. Landfill
sites are a common final disposal site for waste from
urban areas. In lower-income countries there may
simply be a hole in the ground where open dumping
occurs. In higher-income countries, there are much stricter regulations and the types of material that can
be sent to landfill are often defined by law. In the UK,
most landfill sites now control and collect the gas that
is released by the decomposing waste, often using it to
generate electricity through turbines.
Burial 2
The environmental problems caused by landfills can be
numerous. The greenhouse gas methane is produced by
rotting organic matter and other chemicals like bleach
and ammonia can produce toxic gases that negatively
impact the quality of air in the vicinity. Dust and other
forms of non-chemical contaminants can also make
their way into the atmosphere. Landfills can also affect
(ground waltet and river awaliv/brezusrioxic
Submergent e
Since 1999, Singapore has been incinerating much of
its waste and sending the incineration ash and non-
incinerable waste to an offshore landfill called Semakau
Landfill. The Semakau site has been formed by the
construction of a dyke in the shallow sea. It is lined
with an impermeable membrane to stop leakage into
the sea below. Each cell is covered with a layer of earth
once it has been filled to ground level. Subsequently,
grass and trees take root to form a green landscape.
The actual submergence of waste in oceans is banned
by international convention but, according to the
United Nations, some companies have been dumping
radioactive waste and other hazardous materials into
the coastal waters off Somalia, taking advantage of the
fact that the country lacks strong governance.
