In-situ 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. 

Summary of In Situ Chemical Treatment Methods for Organics... 

Surfactant washing is among the most promising in situ chemical treatment methods. Surfactants can improve the solvent property of the flushing water, emulsify nonsoluble organics, and enhance the removal of hydrophobic organics sorbed onto soil particles. 

In situ chemical treatment Injects chemicals to transform contaminants in place Inefficient in low-permeability zones and complex geologic... 

Whereas the approach taken in this investigation has been to create insoluble hydrophobic surface-active reagents by the in situ chemical treatment of asphalt, future researchers may find it more convenient to use readily available petroleum sulfonates or carboxylates as additives. The use of low molecular weight carboxylic elastomers, for example, may permit improved wet-strength retention as well as increased toughness at low temperatures (22, 23,24). 

At times, in situ chemical treatments are used to remove particular contaminants. This is done by introducing... 

System has the potential to add odier innovative conqionents (such as in situ chemical treatments or sur ctants) ... 

The Strecker reaction has been performed on the aldehyde 182 prepared from L-cysteine [86] (Scheme 28). The imine was formed in situ by treatment with benzylamine, then TMS cyanide was added to afford prevalently in almost quantitative yield the syn-diamine 183, which is the precursor of (-l-)-biotin 184. The syn selectivity was largely affected by the solvent, toluene being the solvent of choice. Since the aldehyde 182 is chemically and configurationally unstable, a preferred protocol for the synthesis of 183 involved the prehminary formation of the water-soluble bisulfite adduct 185 and the subsequent treatment with sodium cyanide. Although in this case the syn selectivity was lower, both diastereomers could be transformed to (-l-)-biotin. 

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. 

In situ soil remediation with physical methods includes the in situ heating (in situ thermal treatment), ground-freezing, hydraulic fracturing, immobilization/stabilization, flushing, chemical detoxification, vapor extraction, steam extraction, biodegradation/bioremediation, electroosmosis/ electrokinetic processes, etc. 

T0473 Lawrence Livermore National Laboratory, Direct Chemical Oxidation T0479 Limnofix, Inc., Limnofix In Situ Sediment Treatment (LIST)... 

Can be used to enhance the performance of several in situ technologies, including bioremediation, in situ chemical oxidation, in situ thermal treatments, and in situ solidification. 

This chapter presents the theory and application of zero-valent iron and includes the relevant in situ chemical/physical processes. To illustrate these in situ technologies, the basic mechanisms of adsorption reduction and oxidation processes are discussed for in situ treatment of (1) organic pollutants, (2) heavy metals, and (3) mixtures of organic and inorganic pollutants. The history of zero-valent iron, current applications, mechanisms and kinetics of the system, system improvements, and advantages and disadvantages for zero-valent iron are also discussed. 

A convenient HPLC technique known as the Fukushima-Nixon method has been widely used for selective analyses of tetrahydrobiopterin and tetrahy-droneopterin in biological samples [49]. This method allows the estimation of concentrations of tetrahydropterins based on difference in the concentrations of the corresponding aromatic pterins in the samples, which are prepared in situ by treatment with iodine under acidic and basic conditions. The Fukushima-Nixon method does not require special techniques or equipment for the chemical reaction the sample is simply subjected to oxidation just before its injection into the HPLC column. For example, tetrahydrobiopterin (43) was selectively oxidized to biopterin (30) by iodine in the presence of... 

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