Remedial technologies methods

Another classification of remediation technologies describes where the action is taking place. Ex situ methods are those applied to excavated soil and in situ processes are those applied to the soil in its original location. On-site techniques are those that take place on the contaminated site they can be either ex situ or in situ. Off-site processes treat the excavated soil in fixed industrial facilities, away from the contaminated site. 

Filtration is an efficient and inexpensive method for removing dust, particulates and bioaerosols from indoor air. High efficiency filters can remove up to 95 % of airborne particles as small as 0.3 microns. However, odor associated with gaseous VOCs cannot be removed by simple filtration and must be captured using adsorbents such as activated carbon and charcoal. Frequent replacement is needed since these adsorbents have finite capacity and cannot be regenerated. The aim of this project is to develop an effective remediation technology for common airborne VOCs found indoor. 

Pollution of soils and waters by human activities is an important and widespread problem. This pollution by, organic and inorganic substances can affect individual organisms, human populations, and ecosystems, each in its own unique way. In particular former military installations, often used for weapons production and nuclear power plants represent a ongoing and substantial threat to environment and human health because of the specific pollutants that can be released Solvents, explosives, fuels, radionuclides, heavy metals, and metalloids all have been identified in the environment around these installations. Remediation technologies for these contaminated sites have been developed based on conventional systems utilising physical and chemical treatments, such as excavation and incineration, pump-and-treat methods, ultraviolet oxidation, soil washing, etc. 

Cost effective compared to current remediation technologies such as steam injection, bioventing, soil vapor extraction (SVE), and pump-and-treat methods. 

The Barometrically Enhanced Remediation Technology (BERT ) removes and recovers volatile organic contaminants from soil by enhancing the natural air exchange that occurs in soil as a response to changes in atmospheric pressure. This process is sometimes referred to as barometric pumping or passive soil vapor extraction. The process is a low-cost complement to conventional active-extraction methods because investment and maintenance costs are low and no power is needed. The passive process is better suited than conventional methods for certain problems. 

Phytoremediation can be placed in the bioremediation category as either an in situ or ex situ remediation technology, depending on the approach used. It uses plants and associated micro-organisms to extract, degrade, and stabilize PAHs. If the plants are used in place, the method is in situ. If the soil is excavated and taken to a greenhouse, then the method is classified as ex situ. 

Soil contamination also can be very difficult to detect. New analytical methods have made it possible to detect and analyze dioxins, polyaromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs). Analytical techniques have made it possible to detect the presence of these substances, determine whether remediation is needed, and evaluate the extent to which it has been carried out. Chemistry has provided or contributed to the remediation technologies that have been developed,... 

Whereas there are numerous remediation technologies available,1,4 6 the selected remediation method for any particular site would be dependent on site specific requirements. Any contamination can impact ... 

Whereas a chapter1 in an earlier issue of this series summarised the full range of remediation methods available, this chapter introduces overall remediation approaches and then details a selection of innovative approaches that are starting to be applied within the UK. Emphasis is on remediation technologies that are essentially in situ techniques and which generally involve minimal disturbance of the ground surface. 

Based on the laboratory experimental and field application results, electrokinetic remediation technology has been shown to be a promising method for simultaneously recovering multiple metal contaminants. However, the process is accompanied by limitations on the removal of several specific heavy metals. In this last section, the previous investigations, which focused on the removal of heavy metals, including Cr, As, and Hg, will be examined in more detail. Heavy metals have some reasonable properties, which should be considered more specifically ... 

Applying this soil remediation technology requires special expertise this chapter describes the technology and its applications, indicating the materials and decontamination methods that can be used and how the system should be initiated and controlled. It also specifies the samples that need to be taken in order to monitor the decontamination process. Before remediation can commence, however, it is first necessary to clarify where contamination is present in the area of soil concerned and in what form. It is furthermore necessary to perform electrokinetic laboratory tests with one or preferably more representative soil samples. Finally, it is explained how the data are analyzed and used for carrying out the design of the remediation system. 

Effective treatment or containment of dissolved contaminant plumes and NAPE phases in the capillary fringe or saturated zones represent a continuing challenge to remediation technologies. Effective source control measures depend on careful delineation (in three dimensions) of contaminants, and characterization efforts may limit the success of saturated zone contaminant treatment or control measures. Selected treatment or containment methods for the saturated zone are provided in Table VII. Flow barriers constmcted by slurry wall, grout injection, or sheet pile methods have been used in some instances to channel or contain contaminated groundwater usually in combination with pumping control methods. 

The EPA has long ago concluded that the enviromnental pump-and-treat remediation technology that has been used for removing NAPL hydrocarbon contaminants from aquifers is not working [2]. Indeed, field demonstrations of soil flushing have illustrated potential problems [13], and aquifers contaminated with DNAPLs were shown to be extremely difficult to remediate with the standard pump-and-treat methods. 

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