What is monitored natural attenuation?

What is monitored natural attenuation?

Monitored natural attenuation (MNA) is an in situ remediation technology that relies on naturally occurring and demonstrable processes in soil and groundwater which reduce the mass and concentration of the contaminants.

What is natural attenuation?

Natural attenuation relies on natural processes to decrease or “attenuate” concentrations of contaminants in soil and groundwater. The entire process is called “monitored natural attenuation” or “MNA.” Natural attenuation occurs at most contaminated sites.

What are MNA parameters?

Monitored natural attenuation (MNA) can be an effective and low-cost approach for remediation of contaminated sites. MNA includes physical, chemical and biological processes that reduce contaminant mass or concentration in soil or groundwater under intrinsic condtions.

What type of microbial evidence is required during natural attenuation?

The EPA [18] of the United States was the first to propose that three lines of evidence for natural attenuation should be applied to demonstrate that natural attenuation is taking place: (1) documented decrease in contaminant concentrations at the site, (2) documented geochemical or geomicrobiological conditions …

What is monitored natural attenuation MNA in the contaminated land remediation context?

Definition of Monitored Natural Attenuation (MNA) Application of natural attenuation requires demonstration that natural processes are occurring at a rate that a) protects the wider environment and b) achieves remedial objectives within a reasonable time-frame.

What is natural attenuation in bioremediation?

Natural attenuation refers to processes that naturally transform contaminants to less harmful forms or immobilize contaminants so that they are less of a threat to the environment; see “Natural Attenuation for Groundwater Remediation” by the National Research Council (National Research Council, 2000).

What causes natural attenuation?

Natural attenuation relies on subsurface processes such as dilution, dispersion, sorption, volatilization, and biodegradation to effectively reduce contaminant toxicity, mobility, or volume to levels that are below drinking water guidelines (Wiedemeier et al., 1995).

What is Remediation by enhanced natural attenuation?

Remediation by enhanced natural attenuation (RENA) is a land farming treatment technology for intervention in petroleum hydrocarbon contaminated soils in the Niger Delta regions (Awobajo 1981, Ifeadi and Nwankwo 1980, Odeyemi and Ogunseitan, 1985, Odu, 1972).

What is biostimulation used for?

Biostimulation involves the modification of the environment to stimulate existing bacteria capable of bioremediation. This can be done by addition of various forms of rate limiting nutrients and electron acceptors, such as phosphorus, nitrogen, oxygen, or carbon (e.g. in the form of molasses).

What is the process of phytoremediation?

Phytoremediation is a bioremediation process that uses various types of plants to remove, transfer, stabilize, and/or destroy contaminants in the soil and groundwater.

What is remediation by enhanced natural attenuation?

What is phytoremediation process?

Phytoremediation is a bioremediation process that uses various types of plants to remove, transfer, stabilize, and/or destroy contaminants in the soil and groundwater. In this process, chemical compounds produced by the plant immobilize contaminants, rather than degrade them.

What is monitored natural attenuation (MNA)?

Monitored natural attenuation (MNA) consists of a range of naturally-occurring in situ physical, chemical, and biological processes that attenuate contaminant concentrations in groundwater to achieve remedial goals within a reasonable timeframe, and protect human health and the environment.

What contaminants can be treated with MNA?

These documents describe the application of MNA to treat a wide range of contaminants, including petroleum hydrocarbon constituents, chlorinated solvents, metals, and radionuclides, and the natural attenuation processes that can reduce contaminant mass and/or concentrations over time.

Can site COCs be remediated via natural attenuation processes?

Three lines of evidence may be evaluated to confirm that site COCs can be remediated via natural attenuation processes: Examine historical contaminant trends to determine if contaminant mass and/or concentrations are decreasing over time or have reached plateau levels due to matrix diffusion or other mass transfer limitations.

Is MNA a viable remedy at a site?

Appropriate institutional controls or point-of-use treatment may be required until natural attenuation reaches remedial goals. To assess whether MNA is a viable remedy at a site, the following lines of evidence should be demonstrated by site data (NAVFAC, 2008; ITRC, 2008; EPA, 2008; AFCEE, 2007):