Soils and sediments may become contaminated by diesel, petroleum, BTEX, polycyclic aromatic hydrocarbons (PAHs) and other volatile and semi volatile organic compounds. Sediment remediation is the process of neutralizing contaminants and restoring environments to their pre-contamination condition. There is a variety of treatment options available and the choice of which one to use depends on the nature of the contaminant and on the time and money that are available for the procedure.
When the sediments and soils beneath aquatic environments such as harbors and rivers becomes contaminated, their recreational and navigational use can be seriously compromised. By 2004, the Environmental Protection Agency (EPA) had identified approximately 12 dozen sites that needed attention. Of these, nearly half (60) were deemed sufficiently important to merit tracking at the national level; others were considered suitable for attention at the local level.
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.
When the sediments and soils beneath aquatic environments such as harbors and rivers becomes contaminated, their recreational and navigational use can be seriously compromised. By 2004, the Environmental Protection Agency (EPA) had identified approximately 12 dozen sites that needed attention. Of these, nearly half (60) were deemed sufficiently important to merit tracking at the national level; others were considered suitable for attention at the local level.
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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