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Factfile: Disposal options
Landfills are giant rubbish tips, ranging worldwide from open mountains of unmanaged waste, to enclosed, highly-monitored “sanitary landfills” designed to entomb refuse for years.
They present significant health and environmental risks if not well-designed and maintained.
Heaps of waste generate methane, a greenhouse gas. If the technology and funding is available, this can be monitored, released under control and in some cases harnessed as an energy source.
But the risk of explosions and fires is a potential hazard, both in developing countries, where scavengers often trawl through open dumps, and also in countries such as the US, where landfill blazes are thought to be among the largest sources of emissions of toxic chemicals called dioxins.
The other main risk is of toxic substances being washed from the site and contaminating water supplies and land. The threat can be reduced by situating landfills away from areas vulnerable to flooding or earthquakes, lining the site and draining and treating contaminated water from it – again, only if the money and expertise are available.
A few studies in developed countries have shown a correlation between proximity to landfill sites and birth defects – although other factors, such as the income levels of people living near rubbish tips, may play a role.
Finding sites for landfills is also an issue, as space is a valuable commodity in the urban areas where most waste is generated and local opposition is often vehement.
While some decomposition goes on in a landfill, such sites keep the water, biological organisms and light needed to speed the process to a minimum, Decades-old colouring book pages and carrot tops were found intact when a site in Phoenix, US was excavated in one study.
Once landfill sites are filled to capacity and given time to “stabilise”, they are covered and often turned into parks or golf-courses, or, if the waste is sufficiently compacted, built on – although health fears have triggered local opposition to some such projects.
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