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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.
Remediation of sediments is basically an aquatic problem. Once the soils and sediments underlying the nations harbors and inland waterways become compromised by contamination, their use for navigational or recreational purposes is seriously impaired. As at 2004, the Environmental Protection Agency (EPA) had identified approximately twelve dozen sites that needed to be remediated. Of these, 60 were thought to require attention at the national level, while others were deemed suitable for management by local or state authorities, by volunteers or by other federal authorities.
There are three major approaches to managing contaminated sediment. These are dredging, monitored natural recovery and in situ capping. Among the major sources of soil contamination are mining, industrial accidents. In addition to the contaminants listed above, others include pesticides (DDT), Phthalate Esters, metals (lead and mercury), organometals, cyanide, Mononuclear Aromatic Hydrocarbons (MAHs) and chlorinated hydrocarbons (PCBs).
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.
Once a land remediation authority or other government authority requests that an area be remediated, immediate action is necessary for the protection of the environment as well as human health. Remediation is subject to regulatory oversight. In the United States, this oversight is provided by the Environmental Protection Agency (EPA), Region 9.
The remediation process is carried out at the nanotechnological level. This involves the use of nanoparticles. These are between one and 100 nanoparticles in size. A nanometer is the equivalent of 1 x 10 to the minus ninth meter. Nanoparticles have a high surface area:mass ratio, making them very reactive. Their minute size also allows them to infiltrate tiny nooks and crannies in sediments, bringing them into closer proximity to their target contaminants.
The mechanism by which nanoparticles exert their effects is chemical in nature. A nanoparticle carrying decontaminant bumps into a target contaminant and the result is a detoxifyied product. So far, global NanoRem has cleaned up as many as 70 sites throughout the world. Although currently limited to groundwater projects, research is underway to extend the technology to wastewater treatment.
Large-scale nanotechnology does not come cheap. The minute scale of these operations make them highly expensive. Filtering out visible particles is easy. As yet, there are no nanoparticle filters so the approach has to be chemical. Once we crack nanotechnology, the next step is maybe tackling contamination on the picometer scale, which are one thousand times smaller than nanometers.
Remediation of sediments is basically an aquatic problem. Once the soils and sediments underlying the nations harbors and inland waterways become compromised by contamination, their use for navigational or recreational purposes is seriously impaired. As at 2004, the Environmental Protection Agency (EPA) had identified approximately twelve dozen sites that needed to be remediated. Of these, 60 were thought to require attention at the national level, while others were deemed suitable for management by local or state authorities, by volunteers or by other federal authorities.
There are three major approaches to managing contaminated sediment. These are dredging, monitored natural recovery and in situ capping. Among the major sources of soil contamination are mining, industrial accidents. In addition to the contaminants listed above, others include pesticides (DDT), Phthalate Esters, metals (lead and mercury), organometals, cyanide, Mononuclear Aromatic Hydrocarbons (MAHs) and chlorinated hydrocarbons (PCBs).
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.
Once a land remediation authority or other government authority requests that an area be remediated, immediate action is necessary for the protection of the environment as well as human health. Remediation is subject to regulatory oversight. In the United States, this oversight is provided by the Environmental Protection Agency (EPA), Region 9.
The remediation process is carried out at the nanotechnological level. This involves the use of nanoparticles. These are between one and 100 nanoparticles in size. A nanometer is the equivalent of 1 x 10 to the minus ninth meter. Nanoparticles have a high surface area:mass ratio, making them very reactive. Their minute size also allows them to infiltrate tiny nooks and crannies in sediments, bringing them into closer proximity to their target contaminants.
The mechanism by which nanoparticles exert their effects is chemical in nature. A nanoparticle carrying decontaminant bumps into a target contaminant and the result is a detoxifyied product. So far, global NanoRem has cleaned up as many as 70 sites throughout the world. Although currently limited to groundwater projects, research is underway to extend the technology to wastewater treatment.
Large-scale nanotechnology does not come cheap. The minute scale of these operations make them highly expensive. Filtering out visible particles is easy. As yet, there are no nanoparticle filters so the approach has to be chemical. Once we crack nanotechnology, the next step is maybe tackling contamination on the picometer scale, which are one thousand times smaller than nanometers.
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