The sediments and soils that underlie the nation's waterways are subjected to contamination by a range of chemicals - BTEX, diesel, petroleum, polycyclic aromatic hydrocarbons (PAHs) and other organic muddy junk. The process of neutralizing sediments and restoring them to the pristine condition is called sediment remediation. There are many technologies currently available for treating these sediments; the choice is a factor of the nature of the contaminant itself, factored in with the available budget and the urgency of the treatment.
Sedimentary contamination refers specifically to underwater soils. When the sediment underlying rivers and harbors becomes compromised, their navigational and recreational use is impaired. As of 2004, the Environmental Protection Agency estimated there were roughly 144 sites that required cleaning up. Sixty of these were considered major enough to require tracking at the national level, while others could be tackled by state or local authorities, by voluntary action or by other federal agencies.
The three basic approaches to the control of contaminated sediments and soils are: in situ capping, dredging and monitored natural recovery. The main sources of sedimentary contamination are industrial accidents and mining incidents. Additional contaminants to those specified above include phthalate esters, metals and organometals (mercury, lead, etc.), cyanide, chlorinated hydrocarbons (PCBs) and mononuclear aromatic hydrocarbons (MAHs).
Some of these substances are either completely insoluble or only partially soluble in aqueous solvents and end up becoming embedded in aquatic sedimentation. This means these poisons are indetectable in the water column. The organic content of these particles, their size and shape, and the ecology of benthic oranisms (bottom feeders) all promote the steady accumulation of contaminated sediments.
When a government agency such as a land remediation agency identifies an area to be decontaminated, or remediated, imminent action is arequired to protect the environment, not to mention human health. This process is subject to regulatory oversight. In the USA, this is the purview of the EPA, Region Nine.
The process of remediation goes down right to the level of nanotechnology. Specifically, nanoremediation refers to the use of nanoparticles. These are defined as particles between one and one hundred nanometers in size. One nanometer is equal to one billionth of a meter. Nanoparticles have a high surface area per unit mass, which makes them highly reactive. Their small size also allows them to infiltrate tiny pores in sediments, making target contaminants more accessible.
During the nanoremediation process, a decontaminant on the nanoparticle scale comes into contact with a target contaminant in a detoxification reaction. To date, the global nanoremediation project has identified up to 70 sites around the world that require this type of treatment. Currently, nanorem treatment has been used to clean up groundwater projects, although research is being conducted into using it for wastewater treatment.
What makes nanoremediation fascinating is the scale of the contaminants being removed. It is easy to filter out particles on the micrometer level (one millionth of a meter); nanoparticles are more challenging. Onced the nanoremediation technology has been perfected, perhaps man can start developing technologies to tackle pico particles, which are one thousandth the size of a nanometer.
Sedimentary contamination refers specifically to underwater soils. When the sediment underlying rivers and harbors becomes compromised, their navigational and recreational use is impaired. As of 2004, the Environmental Protection Agency estimated there were roughly 144 sites that required cleaning up. Sixty of these were considered major enough to require tracking at the national level, while others could be tackled by state or local authorities, by voluntary action or by other federal agencies.
The three basic approaches to the control of contaminated sediments and soils are: in situ capping, dredging and monitored natural recovery. The main sources of sedimentary contamination are industrial accidents and mining incidents. Additional contaminants to those specified above include phthalate esters, metals and organometals (mercury, lead, etc.), cyanide, chlorinated hydrocarbons (PCBs) and mononuclear aromatic hydrocarbons (MAHs).
Some of these substances are either completely insoluble or only partially soluble in aqueous solvents and end up becoming embedded in aquatic sedimentation. This means these poisons are indetectable in the water column. The organic content of these particles, their size and shape, and the ecology of benthic oranisms (bottom feeders) all promote the steady accumulation of contaminated sediments.
When a government agency such as a land remediation agency identifies an area to be decontaminated, or remediated, imminent action is arequired to protect the environment, not to mention human health. This process is subject to regulatory oversight. In the USA, this is the purview of the EPA, Region Nine.
The process of remediation goes down right to the level of nanotechnology. Specifically, nanoremediation refers to the use of nanoparticles. These are defined as particles between one and one hundred nanometers in size. One nanometer is equal to one billionth of a meter. Nanoparticles have a high surface area per unit mass, which makes them highly reactive. Their small size also allows them to infiltrate tiny pores in sediments, making target contaminants more accessible.
During the nanoremediation process, a decontaminant on the nanoparticle scale comes into contact with a target contaminant in a detoxification reaction. To date, the global nanoremediation project has identified up to 70 sites around the world that require this type of treatment. Currently, nanorem treatment has been used to clean up groundwater projects, although research is being conducted into using it for wastewater treatment.
What makes nanoremediation fascinating is the scale of the contaminants being removed. It is easy to filter out particles on the micrometer level (one millionth of a meter); nanoparticles are more challenging. Onced the nanoremediation technology has been perfected, perhaps man can start developing technologies to tackle pico particles, which are one thousandth the size of a nanometer.
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