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Environmental remediation deals with the removal of
pollution Pollution is the introduction of contaminant Contamination is the presence of a constituent, impurity, or some other undesirable element that spoils, corrupts, infects, makes unfit, or makes inferior a material, physical body, natural en ...

pollution
or
contaminant Contamination is the presence of a constituent, impurity, or some other undesirable element that spoils, corrupts, infects, makes unfit, or makes inferior a material, physical body, natural environment, workplace, etc. Nuances of contamination ...
s from
environmental A biophysical environment is a life, biotic and Abiotic component, abiotic surrounding of an organism or population, and consequently includes the factors that have an influence in their survival, development, and evolution. A biophysical environ ...

environmental
media such as
soil Soil is a mixture In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, comp ...

soil
,
groundwater Groundwater is the water Water (chemical formula H2O) is an , transparent, tasteless, odorless, and , which is the main constituent of 's and the s of all known living organisms (in which it acts as a ). It is vital for all known form ...

groundwater
,
sediment Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently sediment transport, transported by the action of wind, water, or ice or by the force of gravity acting on the particles. ...

sediment
, or
surface water Surface water is water Water (chemical formula H2O) is an , transparent, tasteless, odorless, and , which is the main constituent of 's and the s of all known living organisms (in which it acts as a ). It is vital for all known forms of ...
.
Remedial action A remedial action is a change made to a nonconforming product or service to address the deficiency. This also can refer to restoration of a landscape from industrial activity Rework and repair are generally the remedial actions taken on products, ...
is generally subject to an array of
regulatory Regulation is the management of complex systems according to a set of rules and trends. In systems theory, these types of rules exist in various fields of biology and society, but the term has slightly different meanings according to context. For ...
requirements, and may also be based on assessments of human
health Health, according to the World Health Organization The World Health Organization (WHO) is a specialized agency of the United Nations United Nations Specialized Agencies are autonomous organizations working with the United Nations and each ...

health
and
ecological Ecology (from el, οἶκος, "house" and el, -λογία, label=none, "study of") is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers organisms In biology ...
risks where no legislative standards exist, or where standards are advisory.


Remediation standards

In the
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...

United States
, the most comprehensive set of Preliminary Remediation Goals (PRGs) is from the
Environmental Protection Agency A biophysical environment is a biotic Biotics describe living or once living components of a community; for example organisms, such as animals and plants. Biotic may refer to: *Life, the condition of living organisms *Biology, the study of life ...
(EPA) Region 9. A set of standards used in
Europe Europe is a continent A continent is any of several large landmass A landmass, or land mass, is a large region In geography Geography (from Greek: , ''geographia'', literally "earth description") is a field of scienc ...

Europe
exists and is often called the
Dutch standards Dutch Standards are environmental pollutant reference values (i.e., concentrations in environmental medium) used in environmental remediation, investigation and cleanup. Barring a few exceptions, the target values are underpinned by an environmenta ...
. The
European Union The European Union (EU) is a political and economic union of member states that are located primarily in Europe Europe is a which is also recognised as part of , located entirely in the and mostly in the . It comprises the wester ...

European Union
(EU) is rapidly moving towards Europe-wide standards, although most of the
industrialised Factories, refineries, mines, and agribusiness are all elements of industrialisation Industrialisation ( alternatively spelled industrialization) is the period of social and economic change that transforms a human group from an agrarian societ ...
nations in
Europe Europe is a continent A continent is any of several large landmass A landmass, or land mass, is a large region In geography Geography (from Greek: , ''geographia'', literally "earth description") is a field of scienc ...

Europe
have their own standards at present. In
Canada Canada is a country in the northern part of North America North America is a continent A continent is any of several large landmasses. Generally identified by convention (norm), convention rather than any strict criteria, ...

Canada
, most standards for remediation are set by the provinces individually, but the Canadian Council of Ministers of the Environment provides guidance at a federal level in the form of the ''Canadian Environmental Quality Guidelines'' and the ''Canada-Wide Standards, Canada-Wide Standard for Petroleum Hydrocarbons in Soil''.


Site assessment

Once a site is suspected of being contaminated there is a need to assess the contamination. Often the assessment begins with preparation of a Phase I Environmental Site Assessment. The historical use of the site and the materials used and produced on site will guide the assessment
strategy Strategy (from Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is approxim ...

strategy
and type of
sampling Sampling may refer to: *Sampling (signal processing), converting a continuous signal into a discrete signal *Sample (graphics), Sampling (graphics), converting continuous colors into discrete color components *Sampling (music), the reuse of a sound ...
and
chemical analysis Analytical chemistry studies and uses instruments and methods used to separate, identify, and quantify matter. In practice, separation, identification or quantification may constitute the entire analysis or be combined with another method. Separ ...
to be done. Often nearby sites owned by the same company or which are nearby and have been reclaimed, levelled or filled are also contaminated even where the current land use seems innocuous. For example, a car park may have been levelled by using contaminated waste in the fill. Also important is to consider off site contamination of nearby sites often through decades of emissions to
soil Soil is a mixture In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, comp ...

soil
,
groundwater Groundwater is the water Water (chemical formula H2O) is an , transparent, tasteless, odorless, and , which is the main constituent of 's and the s of all known living organisms (in which it acts as a ). It is vital for all known form ...

groundwater
, and air. Ceiling dust,
topsoil Topsoil is the upper, outermost layer of soil Soil is a mixture In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements t ...
, surface and groundwater of nearby properties should also be tested, both before and after any remediation. This is a controversial step as: # No one wants to have to pay for the cleanup of the site; # If nearby properties are found to be contaminated it may have to be noted on their
property Property is a system of rights that gives people legal control of valuable things, and also refers to the valuable things themselves. Depending on the nature of the property, an owner of property may have the right to consume, alter, share, r ...
title, potentially affecting the value; # No one wants to pay for the cost of assessment. Often
corporation A corporation is an organization—usually a group of people or a company—authorized by the State (polity), state to act as a single entity (a legal entity recognized by private and public law "born out of statute"; a legal person in legal ...

corporation
s which do voluntary testing of their sites are protected from the reports to environmental agencies becoming public under Freedom of Information Acts, however a "Freedom of Information" inquiry will often produce other documents that are not protected or will produce references to the reports.


Funding remediation

In the US there has been a mechanism for
tax A tax is a compulsory financial charge or some other type of levy imposed on a taxpayer (an individual or legal entity In law Law is a system A system is a group of Interaction, interacting or interrelated elements that act accord ...
ing polluting industries to form a
Superfund The United States The United States of America (USA), commonly known as the United States (U.S. or US), or America, is a country Contiguous United States, primarily located in North America. It consists of 50 U.S. state, states, a Washin ...
to remediate abandoned sites, or to
litigate A lawsuit is a proceeding by a party or parties against another in the Civil law (common law), civil court of law. The archaic term "suit in law" is found in only a small number of laws still in effect today. The term "lawsuit" is used in ref ...
to force corporations to remediate their contaminated sites. Other countries have other mechanisms and commonly sites are rezoned to "higher" uses such as high density housing, to give the land a higher value so that after deducting cleanup costs there is still an incentive for a developer to purchase the land, clean it up, redevelop it and sell it on, often as apartments (home units).


Mapping remediation

There are several tools for mapping these sites and which allow the user to view additional information. One such tool is
TOXMAP TOXMAP was a geographic information system (GIS) from the United States National Library of Medicine The United States National Library of Medicine (NLM), operated by the Federal government of the United States, United States federal government, ...
, a Geographic Information System (GIS) from the Division of Specialized Information Services of the
United States National Library of Medicine The United States National Library of Medicine (NLM), operated by the United States federal government The federal government of the United States (U.S. federal government or U.S. government) is the national government of the United Sta ...
(NLM) that uses maps of the United States to help users visually explore data from the
United States Environmental Protection Agency The Environmental Protection Agency (EPA) is an Independent agencies of the United States government, independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon pro ...
's (EPA)
Superfund The United States The United States of America (USA), commonly known as the United States (U.S. or US), or America, is a country Contiguous United States, primarily located in North America. It consists of 50 U.S. state, states, a Washin ...
and
Toxics Release Inventory The Toxics Release Inventory (TRI) is a publicly available database containing information on toxic chemical releases and other waste management activities in the United States. Image:TRI-ME2006.jpg, TRI-ME, the TRI computer reporting program Summa ...
programs.


Technologies

Remediation technologies are many and varied but can generally be categorized into ex-situ and in-situ methods. Ex-situ methods involve excavation of affected soils and subsequent treatment at the surface as well as extraction of contaminated groundwater and treatment at the surface. In-situ methods seek to treat the contamination without removing the soils or groundwater. Various technologies have been developed for remediation of oil-contaminated soil/sediments. Traditional remediation approaches consist of soil excavation and disposal to
landfill A landfill site, also known as a tip, dump, rubbish dump, garbage dump, or dumping ground, is a site for the disposal of waste Waste (or wastes) are unwanted or unusable materials. Waste is any substance which is discarded after primar ...

landfill
and
groundwater Groundwater is the water Water (chemical formula H2O) is an , transparent, tasteless, odorless, and , which is the main constituent of 's and the s of all known living organisms (in which it acts as a ). It is vital for all known form ...

groundwater
"pump and treat". In-situ technologies include but are not limited to: solidification and stabilization, soil vapor extraction, permeable reactive barriers, monitored natural attenuation,
bioremediation Bioremediation is a process used to treat Contamination, contaminated media, including water, soil and subsurface material, by altering environmental conditions to stimulate growth of Microorganism, microorganisms and degrade the target pollutants. ...
-
phytoremediation Phytoremediation technologies use living plants Plants are predominantly photosynthetic Photosynthesis is a process used by plants and other organisms to Energy transformation, convert light energy into chemical energy that, through c ...
, chemical oxidation, steam-enhanced extraction and
in situ thermal desorption In situ thermal desorption (ISTD) is an intensive thermally enhanced environmental remediation technology that uses thermal conductive heating (TCH) elements to directly transfer heat to environmental media. The ISTD/TCH process can be applied at lo ...
and have been used extensively in the USA.


Thermal desorption

Thermal desorption is a technology for soil remediation. During the process a desorber volatilizes the contaminants (e.g. oil, mercury or hydrocarbon) to separate them from especially soil or sludge. After that the contaminants can either be collected or destroyed in an offgas treatment system.


Excavation or dredging

'' Excavation'' processes can be as simple as hauling the
contaminated soil Image:Soilcontam.JPG, 280px, Excavation showing soil contamination at a disused gasworks in England. Soil contamination or soil pollution as part of land degradation is caused by the presence of xenobiotics (human-made) chemicals or other alteratio ...
to a regulated
landfill A landfill site, also known as a tip, dump, rubbish dump, garbage dump, or dumping ground, is a site for the disposal of waste Waste (or wastes) are unwanted or unusable materials. Waste is any substance which is discarded after primar ...

landfill
, but can also involve
aerating
aerating
the excavated material in the case of
volatile organic compounds (VOCs)
volatile organic compounds (VOCs)
. Recent advancements in
bioaugmentationBiological augmentation is the addition of archaea Archaea ( ; singular archaeon ) constitute a domain of single-celled organisms. These microorganisms lack cell nuclei and are therefore prokaryotes. Archaea were initially classified as ba ...
and biostimulation of the excavated material have also proven to be able to remediate semi-volatile organic compounds (SVOCs) onsite. If the contamination affects a river or bay bottom, then
dredging Dredging is the excavation of material from a water environment. Possible reasons for dredging include improving existing water features; reshaping land and water features to alter drainage Drainage is the natural or artificial remova ...
of
bay mud Bay mud consists of thick deposits of soft, unconsolidated silty clay, which is saturated with water; these soil layers are situated at the bottom of certain estuary, estuaries, which are normally in temperate regions that have experienced cyclica ...
or other
silt Silt is granular material A granular material is a conglomeration of discrete solid, macroscopic scale, macroscopic particles characterized by a loss of energy whenever the particles interact (the most common example would be friction when gra ...
y
clay Clay is a type of fine-grained natural soil Surface-water- gley developed in glacial till, Northern Ireland.">Northern_Ireland.html" ;"title="glacial till, Northern Ireland">glacial till, Northern Ireland. Soil is a mixture of organic m ...

clay
s containing contaminants (including
sewage sludge Sewage (or domestic sewage, domestic wastewater, municipal wastewater) is a type of that is produced by a of people. It is typically transported through a . Sewage consists of wastewater discharged from residences and from commercial, instit ...
with harmful microorganisms) may be conducted. Recently, ExSitu Chemical oxidation has also been utilized in the remediation of contaminated soil. This process involves the excavation of the contaminated area into large bermed areas where they are treated using chemical oxidation methods.


Surfactant enhanced aquifer remediation (SEAR)

Also known as solubilization and recovery, the ''surfactant enhanced aquifer remediation'' process involves the injection of hydrocarbon mitigation agents or specialty
surfactants Surfactants are compounds that lower the surface tension Surface tension is the tendency of liquid surfaces to shrink into the minimum surface area possible. Surface tension is what allows heavier than water i.e., denser than water object ...
into the subsurface to enhance desorption and recovery of bound up otherwise recalcitrant non aqueous phase liquid (NAPL). In geologic formations that allow delivery of hydrocarbon mitigation agents or specialty surfactants, this approach provides a cost-effective and permanent solution to sites that have been previously unsuccessful utilizing other remedial approaches. This technology is also successful when utilized as the initial step in a multi-faceted remedial approach utilizing SEAR then In situ Oxidation, bioremediation enhancement or soil vapor extraction (SVE).


Pump and treat

''Pump and treat'' involves pumping out contaminated groundwater with the use of a submersible or
vacuum pump A vacuum pump is a device that draws gas Gas is one of the four fundamental states of matter In physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its Motion (physics), ...

vacuum pump
, and allowing the extracted groundwater to be purified by slowly proceeding through a series of vessels that contain materials designed to
adsorb Adsorption is the of , s or s from a gas, liquid or dissolved solid to a . This process creates a film of the ''adsorbate'' on the surface of the ''adsorbent''. This process differs from , in which a (the ''absorbate'') is by or a liquid or ...
the contaminants from the groundwater. For petroleum-contaminated sites this material is usually
activated carbon Activated carbon, also called activated charcoal, is a form of carbon Carbon (from la, carbo "coal") is a chemical element with the Symbol (chemistry), symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—making f ...

activated carbon
in granular form. Chemical
reagent A reagent is a substance or compound added to a system to cause a chemical reaction A chemical reaction is a process that leads to the chemical transformation of one set of chemical substance A chemical substance is a form of matter ...
s such as flocculants followed by
sand filter Sand filters are used as a step in the water treatment process of water purification. There are three main types; rapid (gravity) sand filters, upward flow sand filters and slow sand filters. All three methods are used extensively in the water i ...

sand filter
s may also be used to decrease the contamination of groundwater.
Air stripping 250px, Figure 1. An air stripper Air stripping is the transferring of Volatility (chemistry), volatile components of a liquid into an air stream. It is an environmental engineering technology used for the purification of groundwaters and wastewate ...
is a method that can be effective for volatile pollutants such as
BTEX In the petroleum refining An oil refinery or petroleum refinery is an industrial process plant where crude oil is transformed and refined into useful products such as petroleum naphtha, gasoline Gasoline () or petrol () (see the etymol ...
compounds found in gasoline. For most biodegradable materials like
BTEX In the petroleum refining An oil refinery or petroleum refinery is an industrial process plant where crude oil is transformed and refined into useful products such as petroleum naphtha, gasoline Gasoline () or petrol () (see the etymol ...
,
MTBE Methyl ''tertiary''-butyl ether (MTBE), also known as methyl tert-butyl ether and ''tert''-butyl methyl ether, is an organic compound In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the th ...

MTBE
and most hydrocarbons, bioreactors can be used to clean the contaminated water to non-detectable levels. With fluidized bed bioreactors it is possible to achieve very low discharge concentrations which will meet or exceed discharge requirements for most pollutants. Depending on
geology Geology (from the Ancient Greek Ancient Greek includes the forms of the Greek language Greek ( el, label=Modern Greek Modern Greek (, , or , ''Kiní Neoellinikí Glóssa''), generally referred to by speakers simply as Greek ...

geology
and soil type, pump and treat may be a good method to quickly reduce high concentrations of pollutants. It is more difficult to reach sufficiently low concentrations to satisfy remediation standards, due to the equilibrium of
absorption Absorption may refer to: Chemistry and biology *Absorption (chemistry), diffusion of particles of gas or liquid into liquid or solid materials *Absorption (skin), a route by which substances enter the body through the skin *Absorption (pharmacolo ...
/
desorption Desorption is a phenomenon A phenomenon (; plural phenomena) is an observable In physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'nature'), , is the n ...

desorption
processes in the soil. However, pump and treat is typically not the best form of remediation. It is expensive to treat the groundwater, and typically is a very slow process to clean up a release with pump and treat. It is best suited to control the hydraulic gradient and keep a release from spreading further. Better options of in-situ treatment often include air sparge/soil vapor extraction (AS/SVE) or dual phase extraction/multiphase extraction (DPE/MPE). Other methods include trying to increase the dissolved oxygen content of the groundwater to support microbial degradation of the compound (especially petroleum) by direct injection of oxygen into the subsurface, or the direct injection of a slurry that slowly releases oxygen over time (typically magnesium peroxide or calcium oxy-hydroxide).


Solidification and stabilization

Solidification and stabilization work has a reasonably good track record but also a set of serious deficiencies related to durability of solutions and potential long-term effects. In addition CO2 emissions due to the use of cement are also becoming a major obstacle to its widespread use in solidification/stabilization projects. Stabilization/solidification (S/S) is a remediation and treatment technology that relies on the reaction between a binder and soil to stop/prevent or reduce the mobility of contaminants. * Stabilization involves the addition of reagents to a contaminated material (e.g. soil or sludge) to produce more chemically stable constituents; and * Solidification involves the addition of reagents to a contaminated material to impart physical/dimensional stability to contain contaminants in a solid product and reduce access by external agents (e.g. air, rainfall). Conventional S/S is an established remediation technology for contaminated soils and treatment technology for hazardous wastes in many countries in the world. However, the uptake of S/S technologies has been relatively modest, and a number of barriers have been identified including: * the relatively low cost and widespread use of disposal to landfill; * the lack of authoritative technical guidance on S/S; * uncertainty over the durability and rate of contaminant release from S/S-treated material; * experiences of past poor practice in the application of cement stabilization processes used in waste disposal in the 1980s and 1990s (ENDS, 1992); and * residual liability associated with immobilized contaminants remaining on-site, rather than their removal or destruction.


In situ oxidation

New '' in situ oxidation'' technologies have become popular for remediation of a wide range of soil and groundwater contaminants. Remediation by
chemical oxidation
chemical oxidation
involves the injection of strong
oxidant 125px, Dangerous goods label for oxidizing agents An oxidizing agent, also known as an oxidant or oxidizer, is a substance that has the ability to oxidize (mild reducing agent) are added to powdered potassium permanganate Potassium perma ...
s such as
hydrogen peroxide Hydrogen peroxide is a chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entity, molecular entities) composed of atoms from more than one chemical element, element held together ...

hydrogen peroxide
,
ozone Ozone (), or trioxygen, is an inorganic molecule A molecule is an electrically Electricity is the set of physical phenomena associated with the presence and motion Image:Leaving Yongsan Station.jpg, 300px, Motion involves a cha ...

ozone
gas,
potassium permanganate Potassium permanganate is an inorganic compound In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, proper ...

potassium permanganate
or persulfates.
Oxygen Oxygen is the chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements In chemistry, an element is a pure substance consisting only of atoms that all have the same ...

Oxygen
gas or ambient air can also be injected to promote growth of aerobic bacteria which accelerate natural attenuation of organic contaminants. One disadvantage of this approach is the possibility of decreasing anaerobic contaminant destruction
natural attenuation In physics, attenuation or, in some contexts, extinction is the gradual loss of flux intensity through a Transmission medium, medium. For instance, dark glasses attenuate sunlight, lead attenuates X-rays, and water and air attenuate both light an ...
where existing conditions enhance anaerobic
bacteria Bacteria (; common noun bacteria, singular bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typ ...

bacteria
which normally live in the soil prefer a reducing environment. In general though, aerobic activity is much faster than anaerobic and overall destruction rates are typically greater when aerobic activity can be successfully promoted. The injection of
gas Gas is one of the four fundamental states of matter In physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its Motion (physics), motion and behavior through Spacetime, space ...

gas
es into the groundwater may also cause contamination to spread faster than normal depending on the site's
hydrogeology Hydrogeology (''hydro-'' meaning water, and ''-geology'' meaning the study of the Earth Earth is the third planet from the Sun and the only astronomical object known to harbour and support life. 29.2% of Earth's surface is lan ...
. In these cases, injections downgradient of groundwater flow may provide adequate microbial destruction of contaminants prior to exposure to surface waters or drinking water supply wells. Migration of metal contaminants must also be considered whenever modifying subsurface oxidation-reduction potential. Certain metals are more soluble in oxidizing environments while others are more mobile in reducing environments.


Soil vapor extraction

'' Soil vapor extraction'' (SVE) is an effective remediation technology for soil. "Multi Phase Extraction" (MPE) is also an effective remediation technology when soil and groundwater are to be remediated coincidentally. SVE and MPE utilize different technologies to treat the off-gas volatile organic compounds (VOCs) generated after vacuum removal of air and vapors (and VOCs) from the subsurface and include granular activated carbon (most commonly used historically), thermal and/or catalytic oxidation and vapor condensation. Generally, carbon is used for low (below 500 ppmV) VOC concentration vapor streams, oxidation is used for moderate (up to 4,000 ppmV) VOC concentration streams, and vapor condensation is used for high (over 4,000 ppmV) VOC concentration vapor streams. Below is a brief summary of each technology. # Granular
activated carbon Activated carbon, also called activated charcoal, is a form of carbon Carbon (from la, carbo "coal") is a chemical element with the Symbol (chemistry), symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—making f ...

activated carbon
(GAC) is used as a filter for air or water. Commonly used to filter tap water in household sinks. GAC is a highly porous adsorbent material, produced by heating organic matter, such as coal, wood and coconut shell, in the absence of air, which is then crushed into granules. Activated carbon is positively charged and therefore able to remove negative ions from the water such as organic ions, ozone, chlorine, fluorides and dissolved organic solutes by adsorption onto the activated carbon. The activated carbon must be replaced periodically as it may become saturated and unable to adsorb (i.e. reduced absorption efficiency with loading). Activated carbon is not effective in removing heavy metals. # Thermal
oxidation Redox (reduction–oxidation, pronunciation: or ) is a type of chemical reaction A chemical reaction is a process that leads to the chemical transformation of one set of chemical substance A chemical substance is a form of matter ...

oxidation
(or
incineration Incineration is a waste treatment process that involves the combustion Combustion, or burning, is a high-temperature exothermic redox chemical reaction between a fuel (the reductant) and an oxidant, usually atmospheric oxygen, that pr ...
) can also be an effective remediation technology. This approach is somewhat controversial because of the risks of
dioxins Dioxin may refer to: * 1,2-Dioxin or 1,4-Dioxin 1,4-Dioxin (also referred as dioxin or ''p''-dioxin) is a heterocyclic 125px, Pyridine, a heterocyclic compound A heterocyclic compound or ring structure is a cyclic compound that has atoms of ...
released in the
atmosphere An atmosphere (from the greek words ἀτμός ''(atmos)'', meaning 'vapour', and σφαῖρα ''(sphaira)'', meaning 'ball' or 'sphere') is a layer or a set of layers of gases surrounding a planet or other material body, that is held in ...

atmosphere
through the
exhaust gas Exhaust gas or flue gas Flue gas is the gas exiting to the atmosphere via a flue, which is a pipe or channel for conveying exhaust gases from a fireplace, oven, furnace, boiler Poland Poland ( pl, Polska ), officially the Republic ...
es or effluent off-gas. Controlled, high temperature incineration with filtering of exhaust gases however should not pose any risks. Two different technologies can be employed to oxidize the contaminants of an extracted vapor stream. The selection of either thermal or catalytic depends on the type and concentration in parts per million by volume of constituent in the vapor stream. Thermal oxidation is more useful for higher concentration (~4,000 ppmV) influent vapor streams (which require less
natural gas Natural gas (also called fossil gas; sometimes just gas) is a naturally occurring hydrocarbon gas mixture consisting of methane and commonly including varying amounts of other higher alkanes, and sometimes a small percentage of carbon dioxid ...

natural gas
usage) than
catalytic that utilizes a low-temperature oxidation catalyst to convert carbon monoxide to less toxic carbon dioxide Carbon dioxide (chemical formula ) is a colorless gas with a density about 53% higher than that of dry air. Carbon dioxide molecules ...
oxidation at ~2,000 ppmV. * Thermal oxidation which uses a system that acts as a furnace and maintains temperatures ranging from . * Catalytic oxidation which uses a
catalyst Catalysis () is the process of increasing the rate of a chemical reaction A chemical reaction is a process that leads to the chemical transformation of one set of chemical substance A chemical substance is a form of matter In cla ...

catalyst
on a support to facilitate a lower temperature oxidation. This system usually maintains temperatures ranging from . # Vapor condensation is the most effective off-gas treatment technology for high (over 4,000 ppmV) VOC concentration vapor streams. The process involves cryogenically cooling the vapor stream to below 40 degrees C such that the VOCs condensate out of the vapor stream and into liquid form where it is collected in steel containers. The liquid form of the VOCs is referred to as dense non-aqueous phase liquids (DNAPL) when the source of the liquid consists predominantly of solvents or
light non-aqueous phase liquidA light non-aqueous phase liquid (LNAPL) is a groundwater contaminant that is not soluble in water and has lower density than water, in contrast to a DNAPL which has higher density than water. Once a LNAPL infiltrates the ground, it will stop at the ...
s (LNAPL) when the source of the liquid consists predominantly of petroleum or fuel products. This recovered chemical can then be reused or
recycled Recycling is the process of converting waste materials into new materials and objects. The Energy recycling, recovery of energy from waste materials is often included in this concept. The recyclability of a material depends on its ability t ...

recycled
in a more
environmentally sustainable Sustainability is the capacity to endure in a relatively ongoing way across various domains of life. In the 21st century The 21st (twenty-first) century is the current century in the '' Anno Domini'' era or Common Era, in accordance with ...
or
green Green is the color between blue and yellow on the visible spectrum. It is evoked by light which has a dominant wavelength of roughly 495570 Nanometre, nm. In subtractive color systems, used in painting and color printing, it is created by ...

green
manner than the alternatives described above. This technology is also known as cryogenic cooling and compression ( C3-Technology).


Nanoremediation

Using nano-sized reactive agents to degrade or immobilize contaminants is termed
nanoremediation Nanoremediation is the use of nanoparticle A nanoparticle or ultrafine particle is usually defined as a particle of matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having vol ...
. In soil or groundwater nanoremediation,
nanoparticle A nanoparticle or ultrafine particle is usually defined as a particle of matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can be touched ...

nanoparticle
s are brought into contact with the contaminant through either ''in situ'' injection or a pump-and-treat process. The nanomaterials then degrade organic contaminants through
redox Redox (reduction–oxidation, pronunciation: or ) is a type of chemical reaction A chemical reaction is a process that leads to the chemical transformation of one set of chemical substance A chemical substance is a form of matter ...

redox
reactions or adsorb to and immobilize metals such as
lead Lead is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical elements ...

lead
or
arsenic Arsenic is a chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements In chemistry, an element is a pure substance consisting only of atoms that all have the same num ...

arsenic
. In commercial settings, this technology has been dominantly applied to
groundwater remediation Groundwater remediation is the process that is used to treat polluted groundwater by removing the pollutants or converting them into harmless products. Groundwater Groundwater is the water Water (chemical formula H2O) is an , transpare ...
, with research into
wastewater treatment Wastewater treatment is a process used to remove contaminants from wastewater or sewage Sewage, or domestic/municipal wastewater, is a type of wastewater that is produced by a community of people. It is characterized by volume Volume is ...
. Research is also investigating how nanoparticles may be applied to cleanup of soil and gases. Nanomaterials are highly reactive because of their high
surface area The surface area of a solid Solid is one of the four fundamental states of matter 4 (four) is a number A number is a mathematical object A mathematical object is an abstract concept arising in mathematics. In the usual language of ...

surface area
per unit mass, and due to this reactivity nanomaterials may react with target contaminants at a faster rate than would larger particles. Most field applications of nanoremediation have used nano zero-valent iron (nZVI), which may be
emulsified An emulsion is a mixture of two or more liquids that are normally Miscibility, immiscible (unmixable or unblendable) owing to liquid-liquid phase separation. Emulsions are part of a more general class of two-phase systems of matter called colloid ...

emulsified
or mixed with another metal to enhance dispersion. That nanoparticles are highly reactive can mean that they rapidly clump together or react with soil particles or other material in the environment, limiting their dispersal to target contaminants. Some of the important challenges currently limiting nanoremediation technologies include identifying coatings or other formulations that increase dispersal of the nanoparticle agents to better reach target contaminants while limiting any potential toxicity to bioremediation agents, wildlife, or people.


Bioremediation

Bioremediation Bioremediation is a process used to treat contaminated Contamination is the presence of a constituent, impurity, or some other undesirable element that spoils, corrupts, infects, makes unfit, or makes inferior a material, physical body, natural en ...
is a process that treats a polluted area either by altering environmental conditions to stimulate growth of microorganisms or through natural microorganism activity, resulting in the degradation of the target pollutants. Broad categories of
bioremediation Bioremediation is a process used to treat Contamination, contaminated media, including water, soil and subsurface material, by altering environmental conditions to stimulate growth of Microorganism, microorganisms and degrade the target pollutants. ...
include biostimulation,
bioaugmentationBiological augmentation is the addition of archaea Archaea ( ; singular archaeon ) constitute a domain of single-celled organisms. These microorganisms lack cell nuclei and are therefore prokaryotes. Archaea were initially classified as ba ...
, and natural recovery (
natural attenuation In physics, attenuation or, in some contexts, extinction is the gradual loss of flux intensity through a Transmission medium, medium. For instance, dark glasses attenuate sunlight, lead attenuates X-rays, and water and air attenuate both light an ...
).
Bioremediation Bioremediation is a process used to treat contaminated Contamination is the presence of a constituent, impurity, or some other undesirable element that spoils, corrupts, infects, makes unfit, or makes inferior a material, physical body, natural en ...
is either done on the contaminated site (in situ) or after the removal of contaminated soils at another more controlled site (ex situ). In the past, it has been difficult to turn to bioremediation as an implemented policy solution, as lack of adequate production of remediating microbes led to little options for implementation. Those that manufacture microbes for bioremediation must be approved by the EPA; however, the EPA traditionally has been more cautious about negative externalities that may or may not arise from the introduction of these species. One of their concerns is that the toxic chemicals would lead to the microbe's gene degradation, which would then be passed on to other harmful bacteria, creating more issues, if the pathogens evolve the ability to feed off of pollutants.


Collapsing air microbubbles

Cleaning of oil contaminated sediments with self collapsing air microbubbles have been recently explored as a chemical free technology. Air microbubbles generated in water without adding any surfactant could be used to clean oil contaminated sediments. This technology holds promise over the use of chemicals (mainly surfactant) for traditional washing of oil contaminated sediments.


Community consultation and information

In preparation for any significant remediation there should be extensive community consultation. The proponent should both present information to and seek information from the community. The proponent needs to learn about "sensitive" (future) uses like childcare, schools, hospitals, and playgrounds as well as community concerns and interests information. Consultation should be open, on a group basis so that each member of the community is informed about issues they may not have individually thought about. An independent chairperson acceptable to both the proponent and the community should be engaged (at proponent expense if a fee is required). Minutes of meetings including questions asked and the answers to them and copies of presentations by the proponent should be available both on the
internet The Internet (or internet) is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a ''internetworking, network of networks'' that consist ...

internet
and at a local library (even a school library) or community centre.


Incremental health risk

Incremental health risk is the increased
risk In simple terms, risk is the possibility of something bad happening. Risk involves uncertainty Uncertainty refers to Epistemology, epistemic situations involving imperfect or unknown information. It applies to predictions of future events, to ...

risk
that a receptor (normally a human being living nearby) will face from (the lack of) a remediation project. The use of
incremental Increment or incremental may refer to: *Incrementalism, a theory (also used in politics as a synonym for gradualism) *Increment and decrement operators, the operators ++ and -- in computer programming *Incremental computing *Incremental backup, whi ...
health risk is based on
carcinogenic A carcinogen is any substance, radionuclide A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide A nuclide (or nucleide, from atomic nucleus, nucleus, also known as nuclear species) is a class of atoms characte ...
and other (e.g.,
mutagenic In genetics, a mutagen is a physical or chemical agent that permanently changes genetic material, usually DNA, in an organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''organismos'') is any individual cont ...
,
teratogenic Teratology is the study of abnormalities of physiological development in all organisms including plants during the entire life span. It is a sub-discipline in medical genetics Medical genetics is the branch of medicine Medicine is the ...
) effects and often involves value judgements about the acceptable projected rate of increase in
cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumor A benign tumor is a mass of cells Cell most often refers to: * Cell (biolo ...

cancer
. In some
jurisdiction Jurisdiction (from Latin Latin (, or , ) is a classical language A classical language is a language A language is a structured system of communication Communication (from Latin ''communicare'', meaning "to share" or "to be i ...
s this is 1 in 1,000,000 but in other jurisdictions the acceptable projected rate of increase is 1 in 100,000. A relatively small incremental health risk from a single project is not of much comfort if the area already has a relatively high health risk from other operations like incinerators or other emissions, or if other projects exist at the same time causing a greater cumulative risk or an unacceptably high total risk. An analogy often used by remediators is to compare the risk of the remediation on nearby residents to the risks of death through
car accident A traffic collision, also called a motor vehicle collision, car accident or car crash, occurs when a vehicle A vehicle (from la, vehiculum) is a machine A machine is any physical system with ordered structural and functional properti ...
s or
tobacco smoking Tobacco smoking is the practice of burning tobacco Tobacco is the common name of several plants in the ' of the , and the general term for any product prepared from the of these plants. of tobacco are known, but the chief commerci ...

tobacco smoking
.


Emissions standards

Standards are set for the levels of dust, noise, odour, emissions to air and groundwater, and discharge to sewers or waterways of all chemicals of concern or chemicals likely to be produced during the remediation by processing of the contaminants. These are compared against both natural background levels in the area and standards for areas zoned as nearby areas are zoned and against standards used in other recent remediations. Just because the emission is emanating from an area zoned industrial does not mean that in a nearby residential area there should be permitted any exceedances of the appropriate residential standards. Monitoring for compliance against each standards is critical to ensure that exceedances are detected and reported both to authorities and the local community. Enforcement is necessary to ensure that continued or significant breaches result in fines or even a
jail A prison, also known as a jail or gaol (dated, standard English In an English-speaking country This article is intended to provide details and data regarding the geographical distribution of all English speakers, regardless of the legisla ...

jail
sentence Sentence(s) or The Sentence may refer to: Common uses * Sentence (law), the punishment a judge gives to a defendant found guilty of a crime * Sentence (linguistics), a grammatical unit of language * Sentence (mathematical logic), a formula not cont ...
for the polluter. Penalties must be significant as otherwise fines are treated as a normal expense of doing business. Compliance must be cheaper than to have continuous breaches.


Transport and emergency safety assessment

Assessment should be made of the risks of operations, transporting contaminated material, disposal of waste which may be contaminated including workers' clothes, and a formal emergency response plan should be developed. Every worker and visitor entering the site should have a safety induction personalised to their involvement with the site.


Impacts of funding remediation

The rezoning is often resisted by local communities and local government because of the adverse effects on the local amenity of the remediation and the new development. The main impacts during remediation are noise, dust, odour and incremental health risk. Then there is the noise, dust and traffic of developments. Then there is the impact on local traffic, schools, playing fields, and other public facilities of the often vastly increased local population.


Examples of major remediation projects


Homebush Bay, New South Wales, Australia

Dioxins from
Union Carbide Union Carbide Corporation is an American chemical corporation wholly owned (since February 6, 2001) by Dow Chemical Company The Dow Chemical Company (TDCC) is an American multinational chemical corporation headquartered in Midland, Michigan, ...

Union Carbide
used in the production of now-banned pesticide
2,4,5-Trichlorophenoxyacetic acid 2,4,5-Trichlorophenoxyacetic acid (also known as 2,4,5-T), a synthetic auxin Auxins (plural of auxin ) are a class of plant hormone Plant hormones (or phytohormones) are signal molecule In biology, cell signaling (cell signalling in British ...
and defoliant
Agent Orange Agent Orange is a herbicide Herbicides (, ), also commonly known as weedkillers, are substances used to control unwanted plant Plants are predominantly photosynthetic Photosynthesis is a process used by plants and other organi ...

Agent Orange
polluted
Homebush Bay Homebush Bay is a bay on the south bank of the Parramatta River, in the west of Sydney, Australia. The name is also sometimes used to refer to an area to the west and south of the bay itself, which was formerly an official suburb of Sydney, and ...
. Remediation was completed in 2010, but fishing will continue to be banned for decades.


Bakar, Croatia

An EU contract for immobilization of a polluted area of 20,000 m3 in
Bakar Bakar ( it, Buccari, hu, Szádrév) is a town in the Primorje-Gorski Kotar County in western Croatia :* french: link=no, République de Croatie :* hu, Horvát Köztársaság :* it, Repubblica di Croazia :* rue, Републіка Х ...

Bakar
,
Croatia , image_flag = Flag of Croatia.svg , image_coat = Coat of arms of Croatia.svg , anthem = "Lijepa naša domovino ''Lijepa naša domovino'' (; ) is the national anthem A national anthem is a song that ...

Croatia
based on solidification/stabilization with ImmoCem is currently in progress. After 3 years of intensive research by the Croatian government, the EU funded the immobilization project in Bakar. The area is contaminated with large amounts of TPH, PAH, and metals. For the immobilization, the contractor chose to use the mix-in-plant procedure.


See also


General links

*
Biodegradation Biodegradation is the breakdown of organic matter Organic matter, organic material, or natural organic matter refers to the large source of Carbon compounds, carbon-based compounds found within natural and engineered, terrestrial, and aquatic ...
*
Bioremediation Bioremediation is a process used to treat contaminated Contamination is the presence of a constituent, impurity, or some other undesirable element that spoils, corrupts, infects, makes unfit, or makes inferior a material, physical body, natural en ...
* In-situ capping of subaqueous waste * In Situ Oxidation * In-situ thermal desorption *
Ecotoxicity Oil spill creek Ecotoxicity, the subject of study of the field of ecotoxicology (a portmanteau of ecology and toxicology), refers to the potential for biological, chemical or physical stressors to affect ecosystems. Such stressors might occur ...
* Electrokinetic remediation * Electrical resistance heating *
Environmental degradation Environmental degradation is the deterioration of the environment Environment most often refers to: __NOTOC__ * Natural environment, all living and non-living things occurring naturally * Biophysical environment, the physical and biological facto ...
*
Environmental restoration Environmental restoration is closely allied with (or perhaps sometimes used interchangeably with) ecological restoration Restoration ecology is the scientific study supporting the practice of ecological restoration, which is the practice of r ...
*
Groundwater remediation Groundwater remediation is the process that is used to treat polluted groundwater by removing the pollutants or converting them into harmless products. Groundwater Groundwater is the water Water (chemical formula H2O) is an , transpare ...
*
Natural attenuation In physics, attenuation or, in some contexts, extinction is the gradual loss of flux intensity through a Transmission medium, medium. For instance, dark glasses attenuate sunlight, lead attenuates X-rays, and water and air attenuate both light an ...
*
Mold Remediation
Mold Remediation
* Phase I Environmental Site Assessment *
Phytoremediation Phytoremediation technologies use living plants Plants are predominantly photosynthetic Photosynthesis is a process used by plants and other organisms to convert Conversion or convert may refer to: Arts, entertainment, and media * ...
*
Restoration ecology Restoration ecology is the scientific study supporting the practice of ecological restoration, which is the practice of renewing and restoring environmental degradation, degraded, damaged, or destroyed ecosystems and habitats in the Natural envi ...
*
Soil contamination 280px, Excavation showing soil contamination at a disused gasworks in England. Soil contamination or soil pollution as part of land degradation is caused by the presence of xenobiotics (human-made) chemicals or other alteration in the natural soil ...
* Soil Vapor Extraction * Solidification / Stabilization (S/S) with Cement


Legislation about remediation

*
Superfund The United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, stat ...
(
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...

United States
) *Contaminated Land Management Act (
New South Wales New South Wales (abbreviated as NSW) is a state State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', a monthly magazine published by the U.S. Department of State * The State (newspaper), ''The State'' (newspape ...
,
Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

Australia
) *''Contaminated Sites Act 2003'' (
Western Australia Western Australia (abbreviated as WA) is a state State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', a monthly magazine published by the U.S. Department of State * The State (newspaper), ''The State'' (newspape ...

Western Australia
,
Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

Australia
) *'Wet Bodembescherming' (''Soil Protection Act'',
Netherlands ) , national_anthem = ( en, "William of Nassau") , image_map = EU-Netherlands.svg , map_caption = , image_map2 = BES islands location map.svg , map_caption2 = , image_map3 ...

Netherlands
) *'Wet Verontreiniging Oppervlaktewater' (''Surfacewater Pollution Act'',
Netherlands ) , national_anthem = ( en, "William of Nassau") , image_map = EU-Netherlands.svg , map_caption = , image_map2 = BES islands location map.svg , map_caption2 = , image_map3 ...

Netherlands
) *'Environmental Management Act' (
Canada Canada is a country in the northern part of North America North America is a continent A continent is any of several large landmasses. Generally identified by convention (norm), convention rather than any strict criteria, ...

Canada
)


Environmental groups with information

*CHEJ (US - Grew out of
Love Canal Love Canal is a neighborhood in Niagara Falls, New York Niagara Falls is a city A city is a large human settlement.Goodall, B. (1987) ''The Penguin Dictionary of Human Geography''. London: Penguin.Kuper, A. and Kuper, J., eds (1996) ''The ...
controversy) *
Greenpeace Greenpeace is an independent global campaigning network. The network comprises 26 independent national/regional organisations in over 55 countries across Europe, the Americas, Africa, Asia and the Pacific, as well as a co-ordinating body, Green ...

Greenpeace
(International organisation with National sites)


Environmental protection agencies

*
United States Environmental Protection Agency The Environmental Protection Agency (EPA) is an Independent agencies of the United States government, independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon pro ...
*NSW EPA (NSW, Australia) *
Environment Canada Environment and Climate Change Canada (ECCC; french: Environnement et Changement climatique Canada)Environment and Climate Change Canada is the applied title under the Federal Identity Program on the Remote Manipulator System, Canadarm The Fede ...
*
Canadian Canadians (french: Canadiens) are people identified with the country of Canada Canada is a country in the northern part of North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the At ...

Canadian
EPA Summary Table


See also

*
List of cleaning companies This is a list of notable cleaning companies. Cleaning is the process of removing unwanted substances, such as dirt, infectious agents, and other impurities, from an object or environment. Cleaning occurs in various commercial, industrial, environm ...


References


External links


U.S. EPA's Contaminated Site Clean-Up Information (CLU-IN)
{{DEFAULTSORT:Environmental Remediation Pollution control technologies Cleaning and the environment