Groundwater chemical treatment

Technology Description In-situ chemical treatment uses the same principles employed for above-ground chemical processes. Materials are added to neutralize, oxidize or remove contaminants in groundwater or soils in order to avoid digging or pumping of the contaminated waste above ground for... 

Yin, Y. and Allen, H.E., In-Situ Chemical Treatment, Groundwater Remediation Technologies Analysis Center (GWRTAC), Technology Evaluation Report, E Series TE-99-01, 1999. 

Table 16.7 and Table 16.8 summarize some promising in situ chemical treatment methods for organics and inorganics that can be applied to soil. Some of them can also be applied to groundwater. 

The groundwater must also be treated to remove contamination. The costs of this may run as high as 160 per cubic meter. This is based on a figure of. 16 per liter for highly contaminated water. The estimate includes equipment costs and amortization. Equipment needed may include filtration, centrifuges, sedimentation, chemical treatment and any materials disposal. 

For facilities treating groundwater, the predominant technology chosen has been pump and treat. The innovative technologies selected include in situ bioremediation, ex situ bioremediation, thermal desorption, and chemical treatment. The facilities requiring soil treatment are selected based on established technologies, such as off-site disposal and incineration. The innovative technology most often selected has been SVE. 

The substances in Table 8.4 are not normally found alone in the environment but rather in simple or complex mixtures. These mixtures may be associated with the release, storage, or transport of chemicals in surface or groundwater, waste-treatment systems, soils, or sediments. Although many of these chemicals are either consumed or destroyed, a significant portion find their way into the air, waters and soils far away from their original discharge sites. 

Selective removal of dissolved toxic metals from groundwater in combination with chemical treatment... 

Resistance to corrosion due to external and internal environment, including compatibility with different materials external threats such as soils in which the pipe is buried, groundwater, and so forth, and internal factors such as corrosion inhibition and other chemical treatments... 

In order to cope with water scarcity and pollution of the hydrosphere, two main strategies of water treatment are applied (1) chemical treatment of polluted drinking water, surface water, groundwater and (2) chemical treatment of waste-waters containing biocidal or non-biodegradable components. 

Conventional disposal of OP conqwunds involves chemical treatment (hydrolysis), incineration and placement in landfills. The threat of leaching and groundwater contamination makes the use of landfills very undesirable and chemical hydrolj is relies on die use of harsh acids and bases whose byproduct s be disposed of and treated. Incineration remains the only EPA approved metiiod for OP disposal but is publicly opposed due to tire potential release of harmful and toxic byproducts into the atmosphere (3,4). Due to the fact that current disposal me ods inadequately address die removal of OP confounds, new more environmentally fiiendly methods need to be developed (5,d). 

Groundwater is vulnerable to pollution by chemicals carried by rainwater, leaching from waste sites or from waste water carrying industrial or agricultural effluent. Treatment of drinking water may remove some, but not all, of these contaminants. Some polycarbonate or metal water pipes that are lined with epoxy resin lacquers may release bisphenol A. 

Applicability/Limitations. In-situ treatment can be used when it is uneconomical to haul or when infeasible or uneconomical to dig or pump the contaminated waste matrix for treatment in a reactor. This approach should be used whenever excavation or removal causes an increased threat to human health. It can reduce the cost of a remediation program. Because chemicals are applied to the contaminated waste matrix, specifically soil and groundwater, a potential exists for reaction with the soil. Permeability problems can occur as the result of precipitate formation. This can result in inadequate mixing of the contaminant with the treatment chemical. Gas generation may also occur. 

Baird is the 20-acre site of a former chemical mixing and batching company. Poor waste disposal practices resulted in the contamination of groundwater, soil, the municipal water supply, and a brook adjacent to the site. Over one hundred contaminants, including chlorinated and nonchlorinated volatile organics, heavy metals, pesticides, herbicides, and dioxins, had been identified in site soil and groundwater. Remediation activities included soil excavation and incineration, and groundwater treatment (the audit focused on the soil excavation and incineration... 

In situ groundwater treatment is an alternative to the conventional pump-and-treat methods. In situ treatment uses biological or chemical agents or physical manipulations that degrade, remove, or immobilize contaminants. In situ treatment technologies can usually treat both contaminated groundwater and soil. In many instances a combination of in situ and aboveground treatment will achieve the most cost-effective treatment at an uncontrolled waste site. 

A permeable reactive barrier (PRB) is defined as an in situ method for remediating contaminated groundwater that combines a passive chemical or biological treatment zone with subsurface fluid flow management. Treatment media may include zero-valent iron, chelators, sorbents, and microbes to address a wide variety of groundwater contaminants, such as chlorinated solvents, other organics,... 

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