Metals can be dispersed, both naturally and by man's activities, into any of the Earth's elements - soil, water or air. Biological techniques for removing metal pollutants from soil, air or water are now attracting great interest, both because they are seen as more environmentally friendly than chemical treatments, and because, in some cases at least, they can be considerably cheaper.
This text looks chiefly at the ways in which metal ions can be removed from the aquatic environment and looks at the various techniques available, including the use of fungi, algae, peat, compost and bacteria.