Decontamination of soils

An in vitro investigation into the bactericidal effects of a dental ultrasonic descaler on bacterial biofilms using Actinobacillus actinomycctcmcomitans and Porphyromonas gin-givalis has been reported [49]. Suspensions of the bacteria were subjected to the vibrations of a Cavitron PI insert for 2.5 and 5.0 min in an acoustically-simulated model substrate. A 60 % kill rate was achieved at a temperature of around 50 °C which constituted an alternative treatment for bacterial biofilms. This study suggested that a similar approach could be used in the clean-up of a range of biofQms considered to be the cause of a range of environmental hazards. 

Power ultrasound can be used for the rehabilitation of industrial sites or the reclamation of polluted land by the removal of chemical and biological contamination from soil. There are two basic mechanisms through which this can occur either via the removal of contaminated material from the surface of soil particles or the leaching out of more deeply entrenched materials. 

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The minerals processing industry has made contributions to all areas of technology, both in terms of products and processing. Technologies developed in the mineral industry are used extensively in the chemicals industry as well as in municipal and industrial waste treatment and recycling industry, eg, scrap recycling, processing of domestic refuse, automobiles, electronic scrap, battery scrap, and decontamination of soils. 

Berry DF, Boyd SA. 1985. Decontamination of soil through enhanced formation of boimd residues. Environ Sei Teehnol 19 1132-1133. 

The technology is commercially available for the decontamination of soil and porous concrete but is still being developed for the decontamination of water. 

Decontamination of soils using supercritical fluids is an attractive process compared to extraction with liquid solvents because no toxic residue is left in the remediated soil and, in contrast to thermal desorption, the soils are not burned. In particular, typical industrial wastes such as PAHs, PCBs, and fuels can be removed easily [7 to 21]. The main applications are in preparation for analytical purposes, where supercritical fluid extraction acts as a concentration step which is much faster and cheaper than solvent-extraction. The main parameters for successful extraction are the water content of the soil, the type of soil, and the contaminating substances, the available particle-size distribution, and the content of plant material, which can act as adsorbent material and therefore prolong the extraction time. For industrial regeneration, further the amount of soil to be treated has to taken into account, because there exists, so far, no possibility of continuous input and output of solid material for high pressure extraction plants, so that the process has to be run discontinuously. 

DeFlaun, M. F. and Condee, C. W. (1997) Electrokinetic Transport of Bacteria f Journal of Hazardous Materials, Special Edition on Electrochemical Decontamination of Soil and Water, Edited by Yalcin B. Acar and AkramN. Alshawabkeh, pp. 263-278. 

Risoul, V., Renauld, V., Trouve, G., and Gilot, P. (2002). A laboratory pilot study of thermal decontamination of soils polluted by PCBs. Comparison with thermogravimetric analysis. Waste Manage. 22(1), 61-72. 

Dougherty EJ, McPeters AL, Overcash MR, et al. 1993. Theoretical analysis of a method for in situ decontamination of soil contaning 2,3,7,8-tetrachlorodibenzo-p-dioxin. Environ Sci Technol 27(3) 505-515. 

Ibister JD, Anspach GL, Kitchens JF, Doyle RC (1984) Composting for decontamination of soils containing explosives. Microbiologica 7 47-73... 

It is necessary to understand the behavior of soil-water and its mineral components (e.g., nutrients, con taminants) for the purpose of developing conceptual and/or mechanistic process models. Such models can be used to predict nutrient fate in soil-water or contamination-decontamination of soil-water and to develop soil-water remediation-decontamination technologies. To gain an understanding of the soil-water mineral components, their physical and chemical properties need to be known. 

Radio frequency (RF) heating is used for in situ thermal decontamination of soil. This process was originally developed in the 1970s for use in recovering hydrocarbons from materials such as oil shales and tar sands. The treatment is effective for volatile and semivolatile organics only. 

One of the more recent technologies in pollution treatment and remediation is based on the electrokinetic decontamination of soils [126-128], in which a dc potential (a few volts per centimeter) is applied across two inert electrodes embedded in a soil mass. This applied potential causes decomposition of the soil water to occur at the two electrodes. The migration of contaminants in the electric field, water transport, and reactions at the electrodes, as well as reactions caused by the induced pH gradient, can effectively clean soils. Acar et al. [127] reviewed electrokinetic remediation for the removal of metals and other inorganic contaminants from soil as well as its use in the extraction of organics from contaminated soils. 

This entry introduces applications of ozone technology in various areas water and wastewater treatment control of the microbial safety of food decontamination of soils polymer surface modification and bleaching paper pulps. For water and wastewater treatment, in addition to being used alone, ozone is increasingly used in combination with heterogenous catalysts, UV/H2O2 (advanced oxidation process), and biological treatment to enhance ozonation efficiency. The discussion that follows mainly introduces the applications of ozone in water and wastewater treatment because ozone has been both extensively and intensively used in this area however, it does briefly describe other applications. 

Radio Frequency Enhanced Decontamination of Soils Contaminated with Halogenated Hydrocarbons... 

A series of patented (1) processes have been developed for chemical decontamination of soils contaminated with halogenated aromatics, including polychlorinated dibenzo-p-dioxins (PCDD), chlorinated benzenes, polychlorinated biphenyls and similar materials. These processes allow reduction of PCDD levels to less than 1 part per billion (ppb) in as little as two hours at moderate temperatures and pressures. 

The decontamination of soil proceeds in a series of six process steps. 

In Situ Radio Frequency Heating Process for Decontamination of Soil... 

In-situ RF heating offers two alternatives for decontaminating soil. These alternatives are (1) thermal decontamination of soil... 

Dev, H., J. Bridges, and Clark, D. Radio Frequency Enhanced Decontamination of Soils Contaminated with Halogenated Hydrocarbons, Interim Report IIT Research Institute ... 

Hansen HK, Ottosen LM, Lauesen S and ViL-lumsen a (1997) Electrochemical analysis of ion-exchange membranes with respect to a possible use in electrodialytic decontamination of soil polluted with heavy metals. Separation Sci Technol 32 2425 — 2444. 

The suitability of supercritical water for decontamination of soil material can be proved by several semibatch extraction experiments [6]. At 380 °C and 250 bar, the extraction results of hydrocarbons from soil material are excellent, even if it has been weathered for over 20 years. This kind of soil material, often the highly contaminated effluent of a soil washing process, can not be further decontaminated by biological treatment because the hydrocarbon contamination has been exposed to microorganisms throughout the weathering... 

Bonkhoff and Schwuger performed laboratory experiments on decontamination of soils using microemulsions [332]. Pyrene was used as a model contaminant. Repeated washing with water... 

Ernst, W.H.O., 1996. BioavaUabUity of heavy metals and decontamination of soils by plants. Appl. Geochem. 11, 163-167. 

Lara R, Rodriguez-Postigo J, Garcia-Herruzo F. (2005). Decontamination of soils by membrane processes Characterization of membranes under working conditions. Industrial Engineering Chemistry Research 44(2) 400-407. 

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