Environmental remediation is the cleanup of hazardous substances dealing with the removal, treatment and containment of pollution or contaminants from environmental media such as soil, groundwater, sediment. Remediation may be required by regulations before development of land revitalization projects. Developers who agree to voluntary cleanup may be offered incentives under state or municipal programs like New York State's Brownfield Cleanup Program. If remediation is done by removal the waste materials are simply transported off-site for disposal at another location. The waste material can also be contained by physical barriers like slurry walls. The use of slurry walls is well-established in the construction industry. The application of (low) pressure grouting, used to mitigate soil liquefaction risks in San Francisco and other earthquake zones, has achieved mixed results in field tests to create barriers, and site-specific results depend upon many variable conditions that can greatly impact outcomes.
Desorption is the physical process where adsorbed atoms or molecules are released from a surface into the surrounding vacuum or fluid. This occurs when a molecule gains enough energy to overcome the activation barrier and the binding energy that keep it attached to the surface.
Soil contamination, soil pollution, or land pollution as a part of land degradation is caused by the presence of xenobiotic (human-made) chemicals or other alteration in the natural soil environment. It is typically caused by industrial activity, agricultural chemicals or improper disposal of waste. The most common chemicals involved are petroleum hydrocarbons, polynuclear aromatic hydrocarbons, solvents, pesticides, lead, and other heavy metals. Contamination is correlated with the degree of industrialization and intensity of chemical substance. The concern over soil contamination stems primarily from health risks, from direct contact with the contaminated soil, vapour from the contaminants, or from secondary contamination of water supplies within and underlying the soil. Mapping of contaminated soil sites and the resulting clean ups are time-consuming and expensive tasks, and require expertise in geology, hydrology, chemistry, computer modelling, and GIS in Environmental Contamination, as well as an appreciation of the history of industrial chemistry.
Sewage sludge treatment describes the processes used to manage and dispose of sewage sludge produced during sewage treatment. Sludge treatment is focused on reducing sludge weight and volume to reduce transportation and disposal costs, and on reducing potential health risks of disposal options. Water removal is the primary means of weight and volume reduction, while pathogen destruction is frequently accomplished through heating during thermophilic digestion, composting, or incineration. The choice of a sludge treatment method depends on the volume of sludge generated, and comparison of treatment costs required for available disposal options. Air-drying and composting may be attractive to rural communities, while limited land availability may make aerobic digestion and mechanical dewatering preferable for cities, and economies of scale may encourage energy recovery alternatives in metropolitan areas.
For environmental remediation, Low-temperature thermal desorption (LTTD), also known as low-temperature thermal volatilization, thermal stripping, and soil roasting, is an ex-situ remedial technology that uses heat to physically separate petroleum hydrocarbons from excavated soils. Thermal desorbers are designed to heat soils to temperatures sufficient to cause constituents to volatilize and desorb from the soil. Although they are not designed to decompose organic constituents, thermal desorbers can, depending upon the specific organics present and the temperature of the desorber system, cause some organic constituents to completely or partially decompose. The vaporized hydrocarbons are generally treated in a secondary treatment unit prior to discharge to the atmosphere. Afterburners and oxidizers destroy the organic constituents. Condensers and carbon adsorption units trap organic compounds for subsequent treatment or disposal.
Soil vapor extraction (SVE) is a physical treatment process for in situ remediation of volatile contaminants in vadose zone (unsaturated) soils. SVE is based on mass transfer of contaminant from the solid (sorbed) and liquid phases into the gas phase, with subsequent collection of the gas phase contamination at extraction wells. Extracted contaminant mass in the gas phase is treated in aboveground systems. In essence, SVE is the vadose zone equivalent of the pump-and-treat technology for groundwater remediation. SVE is particularly amenable to contaminants with higher Henry’s Law constants, including various chlorinated solvents and hydrocarbons. SVE is a well-demonstrated, mature remediation technology and has been identified by the U.S. Environmental Protection Agency (EPA) as presumptive remedy.
A thermal blanket is a device used in thermal desorption to clean soil contamination. The primary function of a thermal blanket is to heat the soil to the boiling point of the contaminants so that they break down. A vacuum pulls the resulting gas into a separate air cleaner that may use various methods, such as carbon filters and high-heat ovens, to completely destroy the contaminants. Aside from evaporation and volatilization, the contaminants may also be removed from the soil through other mechanisms such as steam distillation, pyrolysis, oxidation, and other chemical reactions.
Havertown Superfund is a 13-acre polluted groundwater site in Havertown, Pennsylvania contaminated by the dumping of industrial waste by National Wood Preservers from 1947 to 1991. The state first became aware of the pollution in 1962 and initiated legal action against the owners in 1973 to force them to cleanup the site. The Environmental Protection Agency (EPA) ranked the site the eighth worst cleanup project in the United States. The site was added to the National Priorities List in 1983 and designated as a Superfund cleanup site in the early 1990s. Remediation and monitoring efforts are ongoing and the EPA transferred control of the site to the Pennsylvania Department of Environmental Protection in 2013.
Groundwater remediation is the process that is used to treat polluted groundwater by removing the pollutants or converting them into harmless products. Groundwater is water present below the ground surface that saturates the pore space in the subsurface. Globally, between 25 per cent and 40 per cent of the world's drinking water is drawn from boreholes and dug wells. Groundwater is also used by farmers to irrigate crops and by industries to produce everyday goods. Most groundwater is clean, but groundwater can become polluted, or contaminated as a result of human activities or as a result of natural conditions.
Electrical resistance heating (ERH) is an intensive in situ environmental remediation method that uses the flow of alternating current electricity to heat soil and groundwater and evaporate contaminants. Electric current is passed through a targeted soil volume between subsurface electrode elements. The resistance to electrical flow that exists in the soil causes the formation of heat; resulting in an increase in temperature until the boiling point of water at depth is reached. After reaching this temperature, further energy input causes a phase change, forming steam and removing volatile contaminants. ERH is typically more cost effective when used for treating contaminant source areas.
The Lipari Landill is an inactive landfill on a 6-acre (2.4 ha) former gravel pit in Mantua Township, New Jersey. It was used from 1958 to 1971 as a dump site for household and industrial wastes. Toxic organic compounds and heavy metals dumped at the site have percolated into the ground water and leached into lakes and streams in the surrounding area. The site has been identified as the worst toxic dump in the United States and was ranked at the top of the United States Environmental Protection Agency's Superfund eligibility list.
Pemaco is a former chemical mixing company and facility located on the Los Angeles River in Maywood, a small city in southeastern Los Angeles County, California.
Electro Thermal Dynamic Stripping Process (ET-DSP) is a patented in situ thermal environmental remediation technology, created by McMillan-McGee Corporation, for cleaning contaminated sites. ET-DSP uses readily available three phase electric power to heat the subsurface with electrodes. Electrodes are placed at various depths and locations in the formation. Electric current to each electrode is controlled continuously by computer to uniformly heat the target contamination zone.
In situ chemical oxidation (ISCO), a form of advanced oxidation process, is an environmental remediation technique used for soil and/or groundwater remediation to lower the concentrations of targeted environmental contaminants to acceptable levels. ISCO is accomplished by introducing strong chemical oxidizers into the contaminated medium to destroy chemical contaminants in place. It can be used to remediate a variety of organic compounds, including some that are resistant to natural degradation. The in situ in ISCO is just Latin for "in place", signifying that ISCO is a chemical oxidation reaction that occurs at the site of the contamination.
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 low (<100 °C), moderate (~100 °C) and higher (>100 °C) temperature levels to accomplish the remediation of a wide variety of contaminants, both above and below the water table. ISTD/TCH is the only major in situ thermal remediation (ISTR) technology capable of achieving subsurface target treatment temperatures above the boiling point of water and is effective at virtually any depth in almost any media. TCH works in tight soils, clay layers, and soils with wide heterogeneity in permeability or moisture content that are impacted by a broad range of volatile and semi-volatile organic contaminants.
The Waste Disposal Inc. Superfund site is an oil-related contaminated site in the highly industrialized city of Santa Fe Springs in Los Angeles County, California. It is approximately 38 acres (15 ha), with St Paul's high school immediately adjacent to the northeast corner of the site. Approximately 15,000 residents of Santa Fe Springs obtain drinking water from wells within three miles (4.8 km) of the site.
The Nebraska Ordnance Plant is a former United States Army ammunition plant located approximately ½ mile south of Mead, Nebraska and 30 miles west of Omaha, Nebraska in Saunders County. It originally extended across 17,250 acres (69.8 km2) producing weapons from 1942-45 after which the Army used it as a bomb factory during the Vietnam War. Environmental investigations in the 1980's found the soil and groundwater contaminated with the explosive RDX and the degreaser trichloroethylene. In 1990, federal agencies added the site to the National Priorities List as a Superfund site. Remediation included soil excavation and water treatment, the latter of which has been ongoing since 1997. Water is contained and treated at 4 treatment plants and the known plumes are monitored at hundreds of wells. The latest wells, dug deeper into the bedrock than previously, showed RDX and TCE above desired action levels in April 2016.
The A.O. Polymer manufacturing site is located in Sparta Township, New Jersey. This facility created special polymers, plastics, and resins. It was also used for reclaiming spent solvents. The facility's poor waste handling led to serious contamination of the ground. It also contaminated the water in the ground with volatile organic compounds. The site has been a threat to the Allentown aquifer, which provides drinking water to over 5,000 people. Initial clean ups started with getting rid of old drums and contaminants from their original disposal area. The company took them and decided to dispose of them elsewhere, thus not fixing the problem. Primary cleanups of the site were ongoing as of 2008. The EPA has been using water pumps to remove contaminants from the water in the ground. A soil extraction system has been put at their disposal to remove harmful contamination within the soil as well. All wells in the affected areas have been closed.
Brook Industrial Park (BIP) is an industrial area occupying 4.5 acres of the Borough of Bound Brook, New Jersey, in the United States of America. It is located on the northern bank of the Raritan River. Industrial, chemical and pesticide operations began in 1971 and eventually lead to the contamination of groundwater and exposure of workers to harmful dioxins. Throughout 1980 to 1988 the United States Environmental Protection Agency (EPA) and the New Jersey Department of Environmental Protection (NJDEP) conducted studies to determine if there were any threats being posed on the workers, community or environment by the BIP companies in their disposal of processed and stored chemicals.
Forest Waste Products is a 120-acre (49-hectare) Superfund site in Forest Township northwest of Otisville, Michigan.
T. McGowan, T., R. Carnes and P. Hulon. Incineration of Pesticide-Contaminated Soil on a Superfund Site, paper on the S&S Flying Services Superfund Site remediation project, Marianna, FL, presented at HazMat '91 Conference, Atlanta, GA, October, 1991
