"Bioremediation is a technology that uses microorganisms to treat contaminants through natural biodegradation mechanisms (intrinsic bioremediation) or by enhancing natural biodegradation mechanisms through the addition of microbes, nutrients, electron donors, and/or electron acceptors (enhanced bioremediation). This technology, performed in situ (below ground or in place) or ex situ (above ground), is capable of degrading organic compounds to less toxic materials such as carbon dioxide (CO2), methane, and water through aerobic or anaerobic processes. Bioremediation is being used with increasing frequency to remediate contaminated media at hazardous waste sites because, compared with other remediation technologies, it often is less expensive and more acceptable to the public."