Microorganisms in the ground have the ability to degrade many toxic chemicals to basic non-toxic by-products including carbon dioxide, water and other benign inorganic compounds. Influencing site conditions to stimulate microbial degradation of contaminants is termed bioremediation. The process uses minimal energy and is considerably less expensive than other more aggressive technologies.
The key to a successful bioremediation project is to ensure that the proper microbial ecology is present to degrade the contaminants of concern. This is achieved through chemically and biologically engineering the contaminated area.
Understanding and, if necessary, enhancing the natural microbiological systems to promote remediation is critical. If the proper organisms are not present, the system can be stimulated (bioaugmented') by adding naturally occurring organisms cultivated from other sites.
Advances in the application of chemicals (oxidants and reductants) to breakdown contaminants has also contributed to the portfolio of cost effective in-situ remediation techniques now available. These chemical oxidation and chemical reduction methods are best suited for rapidly degrading high concentrations of contaminants. They are often unable to achieve the stringent remediation standards required at many US sites, and it is often advantageous to follow chemical treatments with in-situ bioremediation. Used effectively, chemical and biological treatments work well together as a 'treatment train'.
Within less stringent regulatory frameworks, such as the UK and other parts of Europe, chemical oxidation can be used successfully as a standalone technology.