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.
Soil remediation is tackled by three basic approaches: monitored natural recovery, dredging and in situ capping. The sources of the contamination include mining and industrial accidents like oil leaks, chemical spills, etc. As well as the contaminants mentioned earlier, things like pesticides, metals and organometals, cyanide, pthalate esters and hydrocarbons in the form of PCBs and mononuclear aromatic hydrocarbons enter the soil environment.
These chemicals are either only partially soluble or completely insoluble in water and become part of the aquatic sedimentary environments. This means that large volumes of contaminants are present that are not detectable using conventional water technologies. Over time, the ecology of benthic organisms, their organic content and the sizes and shapes of the particles conspire to accumulate sedimentary contamination.
Once a government agency identifies a site to be remediated, prompt action is essential in order to protect human health as well as the environment. All remediation projects require regulatory oversight. In the USA, this is provided by the Region 9 of the EPA.
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.
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.
What makes nanoremediation is the minute scale of the contaminants being removed. Any idiot can filter out junk the size of coffee grounds. Nanoparticles are too small to filter using available technology, and so that is why neutralizing chemical reactions are necessary. Once those are under control, maybe we can start tackling pico particles, which are one thousandth of a billionth of a meter.
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.
Soil remediation is tackled by three basic approaches: monitored natural recovery, dredging and in situ capping. The sources of the contamination include mining and industrial accidents like oil leaks, chemical spills, etc. As well as the contaminants mentioned earlier, things like pesticides, metals and organometals, cyanide, pthalate esters and hydrocarbons in the form of PCBs and mononuclear aromatic hydrocarbons enter the soil environment.
These chemicals are either only partially soluble or completely insoluble in water and become part of the aquatic sedimentary environments. This means that large volumes of contaminants are present that are not detectable using conventional water technologies. Over time, the ecology of benthic organisms, their organic content and the sizes and shapes of the particles conspire to accumulate sedimentary contamination.
Once a government agency identifies a site to be remediated, prompt action is essential in order to protect human health as well as the environment. All remediation projects require regulatory oversight. In the USA, this is provided by the Region 9 of the EPA.
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.
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.
What makes nanoremediation is the minute scale of the contaminants being removed. Any idiot can filter out junk the size of coffee grounds. Nanoparticles are too small to filter using available technology, and so that is why neutralizing chemical reactions are necessary. Once those are under control, maybe we can start tackling pico particles, which are one thousandth of a billionth of a meter.
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