Biodegradation rate of contaminant degradation is fast enough to

Biodegradation is the
process by which organic substances are broken down into smaller compounds by microbial organisms (Marinescu et al., 2009). It is the biologically catalyzed reduction in complexity of
chemical compounds (Alexander, 1994). According to the
interim army policy on natural attenuation for environmental restoration (1995), natural attenuation or bioattenuation is the reduction of pollutant
concentrations in the environment through biological procedures,
physical occurrences, or chemical reactions. One of the most
significant components of this process is biodegradation. Microorganisms
can help with the chemical reactions that alter the form of contaminants and lessen the
risk to all living things. However, the correct conditions must exist underground to clean the polluted sites thoroughly. These conditions are observed to
be sure that natural attenuation is happening. This process
is called monitored natural attenuation
(MNA). MNA is a method used to oversee or examine the development of
bioattenuation processes that can reduce contaminants in soil and groundwater. It can be done with other bioremediation processes as a final option or it can be the only
remediation process if the rate of contaminant degradation
is fast enough to protect human health and the environment. Natural processes can then moderate the residual
amount of pollution, regular monitoring of the soil and groundwater can verify those degradations (EPA, 2001). If the natural attenuation is not quick enough or not finished, bioremediation will be improved by either
biostimulation or bioaugmentation. Biostimulation involves the adding of soil nutrients, trace
minerals, electron acceptors, or electron
donors. It enhances the biotransformation of a
wide range of soil contaminants (Li CH et al., 2010).
Bioaugmentation can be defined as the technique for improvement of the capacity
of a contaminated matrix (soil r other biotope) to remove pollution by the
introduction of specific competent strains or consortia of microorganisms
(Thierry et al., 2008). Bioaugmentation method can be utilized when
biostimulation and natural attenuation have failed (El Fantroussi et al., 2005).