Contaminated soil material

Karathanasis AD, Thompson YL, Evangelou VP. 1990. Temporal solubility trends of aluminum and iron leached from coal spoils and contaminated soil materials. J Environ Qual 19 389-395. 

Extraction results of weathered contaminated soil material in water at 663 K at 24 MPa... 

A new apparatus was developed for continuous extraction of contaminated soil material for high pressure (25 MPa) and high temperature (663 K) operating conditions. The extraction of hydrocarbon contaminants from long weathered and highly contaminated soil material could be realised with supercritical water under parallel flow. Within a residence time of only 28 s suspensions of less than 0.75 wt% soil in water could be cleaned (> 90 %). For a concentration of 1 wt% soil in water 43 s were needed to achieve a clean-up result of 98.3 %. The continuous extraction process can be carried out multistage. Then higher concentrated suspensions (2-4 wt%) can be also cleaned by supercritical water extraction. 

The glass columns used in this study were 38.5 cm long and had a diameter of 4,5 cm. The first 30 cm of the columns were filled with contaminated soil material from the saturated zone of the Testfeld Slid site. The remaining 8.5 cm were filled with water only. Five sampling ports P1-P5 were installed along the column with P1-P4 located throughout the soil-filled part of the column and P5 at the water-filled section. The concentrations recorded at P5 were used to represent the outlet concentrations of the column. In addition, the water was sampled before entering the column. 

A new apparatus (Fig. 12) was built for continuous extraction experiments with contaminated soil material and supercritical water [6]. It consisted of a tubular extractor, a membrane pump for delivering the suspension to the extractor, and the expansion valves. Figure 13 shows semi-batch and continuous extraction results as a function of solvent to soil ratio. Compared to semi-batch extraction, residence times can be reduced... 

The results shown in Table 12.4 demonstrate that for an extractant/soil mass ratio of six the extracted amounts of pyrene from the contaminated soil material is nearly the same for a — 0.5 and a = 0.3. Even for the lower oil content the pyrene concentration is far from the solubilization limit. It is worth noting that the results for the extraction with microemulsions at extraction temperatures much lower than the boiling point of toluene are higher than for the extraction with hot toluene. 

Clean up in such a way tliat the hazardous material is removed and does not produce a future danger. It may be necessary to pump out a hazardous liquid or to remove contaminated soil, etc. Decontamination procedures may be necessaiy. See EPA s Standard Operating Safety Guides for instructions for decontamination required following exposure to different danger levels of liazmds... 

Only two processes, high-temperature pyrolysis and mobile incineration, have proved effective for soil decontamination and are considered to be commercially viable. Both involve heating the contaminated soil to a high temperatnre, which is costly in terms of energy use and materials handling. There are substantial opportunities for innovation and development of processes for the separation of eontaminants from soils and the in-situ treatment of contaminated soils. Examples of each are given in the following subsections. 

Soil surveys relating to construction work require samples from at least the depth of excavation water seepage may cause cross-contamination of land. Some guidelines for the classification of contaminated soils are summarized in Table 13.11 some materials are difficult to dispose of safely on land (Table 13.12). 

An important development has been the isolation of bacteria that were able to degrade phenan-threne that was sorbed to humic acid material (Vacca et al 2005). Enrichment was carried ont with PAH-contaminated soils using phenanthrene sorbed to commercial hnmic acid. Only the strains isolated from this enrichment were able to carry ont degradation of C-labeled phenanthrene, and this exceeded by factors of 4-9 the amonnt estimated to be available from the aqneons phase alone. It was snggested that specially adapted bacteria might interact specifically with natnrally occnrring colloidal material. 

Sometimes it is impossible to effectively design out waste, and safe means have to be found to dispose of it. Many industrial processes produce relatively high levels of waste in a finely divided or dispersed form, such as ash, contaminated soil, treatment sludges, and so forth. This contaminated material is difficult to handle and process. A common approach to tackling this problem is to stabihse and sohdify the waste using a binder that immobilises contaminants within a hard matrix. This does not destroy the contaminants, but keeps them from moving into the surroimding environment. 

The more a source material is processed the less it behaves and reacts like a typical field sample, and if a real-world contaminated soil is ground to reduce the particle size the heat of friction/shearing may alter the composition and constituents may volatilize. 

Biotic Transport Biotic transport can be defined as the actions of plants and animals that result in the transport of a radioactive material or other substance from a waste site to locations where it can enter pathways that may result in exposure to humans. Small mammals are ubiquitous and inhabit areas containing radioactive contamination or radioactive waste sites. Mammals inhabiting these areas may become contaminated with americium by consuming contaminated soil or plants and disturb americium-contaminated soil through their burrowing and excavating activities. These animals may therefore affect the distribution of americium within the waste site or transport americium to previously uncontaminated areas. In addition, small mammals may be consumed by animals higher in the food chain such as hawks and coyotes, which would add to the dispersal of americium from disposal areas. However, results of... 

Brixie JM, Boyd SA (1994) Treatment of contaminated soils with organoclays to reduce leachable pentachlorophenol. J Environ Qual 23 1283-1290 Brown MJ, Burris DR (1996) Enhanced organic contaminant sorption on soil treated with cationic surfactants. Ground Water 34 734-744 Burris DR, Antworth CP (1992) In situ modification of an aquifer material by a cationic surfactant to enhance retardation of organic contaminants. J Contam Hydrol 10 325-337... 

The primary sources of PCP in humans include direct intake by way of diet, air, or water and through contact with PCP-contaminated materials (Uhl et al. 1986). It is now established that PCP is taken up by female rhesus monkeys via the skin from PCP-contaminated soils. Monkeys accumulated up to 24% of the PCP in contaminated California soils over a 24-h period (Wester et al. 

Organic chemicals dissolved in groundwater originate from a release source, which may be point source (defined leak) or it may emanate from an area source, such as a mass of contaminated soil. Once dissolved, the chemicals disperse into the ground-water by molecular diffusion and advection (combined as dispersion), both of which are influenced by equilibrium distribution relationships with the aquifer materials. 

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