All over the country, land is sitting idle. Old coal fields and gasworks, derelict factories and disused landfills dot the country. Property developers love to turn these sites into new housing and office complexes, but before construction can begin, clean up is often the first concern. Old industrial sites frequently suffer from serious contamination; the land is polluted with the spills and leaks of a past era. Most developers take the easy approach to the problem: you dig it out and dump it somewhere else. Whilst it seems strange to send soil to a landfill, at least the contaminants are contained - albeit temporarily. Ironically, the polluted soil holds the secret to its own efficient clean up. Naturally occurring bacteria in the ground soon develop a taste for contaminating organic compounds and use them as a food source. If oxygen is present in the soil, anything from petrol to polyaromatic hydrocarbons (PAHs) are broken down to nothing more than carbon dioxide and water. Even without oxygen, natural degradation (usually to methane, carbon dioxide and hydrogen) is still possible.
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