Electro kinetic REMEDIATION is a promising technology for contaminated clayey soils. In order to estimate the efficiency of process on different soils, knowing the interaction of simultaneous different processes is very important. The results of electro kinetic process are water flow, ion and species migration against an electrical field.In this paper the feasibility of phenol removal from kaolinite using Electro kinetic REMEDIATION is investigated. Results of three one dimentional tests at constant current condition are presented. The tests were conducted for about 50 hours. Variations of pH, electrical gradient, electro osmotic flow and phenol concentration in anode and cathode chambers as well as soil specimen were measured.The efficiency of phenol removal along the soil specimen was calculated at the end of each test. In one case more than 80 percent of phenol removal was achived from soil sample. Results indicated that electro kinetic REMEDIATION is suitable for phenol removal from contaminated clayey soils in short time. Further experiment needed to evalute the efficiency of this technology on contaminant removal of natural polluted soils.

One large group of persistent and toxic contaminants is the hydrophobic organic contaminants. Among them, perchloroethylene has been recognized as a representative group of these pollutants with low solubility. This study reports on the effects of electrokinetic REMEDIATION with non-ionic surfactant on perchloroethylene contaminated soil. The performance of electrokinetic process in treating a clay soil artificially contaminated was investigated with two levels, 10000 and 30000 mg.kg-1 perchloroethylene and 0.33 g.kg-1 Triton-x-100. A direct current power supply with constant direct current electric voltage (1 V.cm-1) was used for 8-16 days. A negatively charged soil surface resulted in a more negative zeta potential and greater electroosmotic flow toward the cathode. The perchloroethylene concentrations were measured after extraction using n-hexane and analyzed by Fourier Transform Infrared Spectroscopy instrument. The water content of soil was kept 25% (w/w). Results were shown that perchloroethylene removal efficiency were achieved to 74 and 89 percent for 10000 and 30000 mg.kg-1 perchloroethylene, respectively for 16 days. Therefore, in this study the integration of electrokinetic with non-ionic surfactant as a hybrid method was most effective for the REMEDIATION of perchloroethylene contaminated soils.

Chromium contaminants emanating from industrial activities pose a significant threat to human’s well-being. Chromium (III) and Chromium (VI) are the forms in which they are commonly encountered, of which the trivalent form is relatively benign. Hence, biological reduction of hexavalent chromium has been widely explored by researchers, yielding fruitful outcomes, opening up exciting avenues and also throwing up new challenges. This article attempts to review this area of research. Microbes, especially bacteria capable of Chromium (VI) reduction, belonging to a heterogeneous group have been isolated from contaminated sites. They exhibit plasmid-mediated chromate resistance and the reduction is enzymatically mediated. Reduction studies have been carried out with free and immobilized enzymes as well as whole cells. Experiments have been carried out in specifically designed bioreactors operated in batch and continuous modes. Although significant progress has been made, much needs to be done for its successful in situ application as the organism may not withstand the Chromium concentration or may be impeded by the presence of other toxicants. With molecular engineering, it may be possible to derive strains with improved performance even under stressful field conditions.

Methanotrophs are unique and ubiquitous bacteria that utilize methane as a sole source of carbon and energy from the atmosphere. Besides, methanotrophs may also be targeted for bioREMEDIATION of diverse type of heavy metals and organic pollutants owing to the presence of broad-spectrum methane monooxygenases enzyme. They are highly specialized group of aerobic bacteria and have a unique capacity for oxidation of certain types of organic pollutants like alkanes, aromatics, halogenated alkenes, etc. Oxidation reactions are initiated by methane monooxygenases enzyme, which can be expressed by methanotrophs in the absence of copper. The present article describes briefly the concerns regarding the unusual reactivity and broad substrate profiles of methane monooxygenases, which indicate many potential applications in bioREMEDIATION of heavy metals and toxic organic compounds. Research is needed to develop understanding in plant-methanotrophs interactions that optimize methanotrophs utilization in the field of environmental REMEDIATION, while supporting other ecosystem services.

Soil forms the main source of agricultural production; hence, preserving its health and fertility plays an important role in sustainable food production. This warrants maintaining adequate soil nutrients and moisture and minimizing its pollutant load. Nanotechnology might be exploited to achieve these goals toward improved soil properties. Applications of nanotechnology in soil science might include the uses of such materials as nanomodifiers to improve the efficiency of agronomic operations and soil aeration, porous nanozeolites for the slow and effective release of nutrients present in chemical fertilizers, nanohydrogels to increase soil water retention capacity and reduce irrigation water, and nanoparticles to remove contaminants from the soil. However, excessive use of nanomaterials might have toxic effects on soil microorganisms. It follows that sound and proper utilization of nanotechnology as an emerging technology might lead to such beneficial outcomes as food security and development of environment-friendly and sustainable agriculture in developing countries.

Physical REMEDIATION technique is one of the primary mechanisms for REMEDIATION of surface contaminated soils by improving the conditions for soil aero microorganism activities. In this study, the ability of physical REMEDIATION technique for REMEDIATION of a petroleum contaminated calcareous soil (Typic Calciargids) with three petroleum contamination levels was evaluated. Contamination levels were consisted of Cx (0: 1 w/w, uncontaminated: contaminated soil), C1 (1: 1 w/w, uncontaminated: contaminated soil) and C2 (1: 3 w/w, uncontaminated: contaminated soil). Results showed that the soil microbial activity was increased at all contamination levels due to physical REMEDIATION processes as compared to the control (without physical REMEDIATION processes). The Co2 evolution due to soil microbial respiration in the C1, C2, and Cx levels was about 19, 25, and 20% more than that in the control, respectively. The most reduction value in the total petroleum hydrocarbon concentration (TPH) was observed in the Cx level at the end of experiment. There was about 52% of reduction in the TPH-contents in the Cx level in comparison with the control which was only 21%. Furthermore, TPH-concentration in the C1 and C2 levels was reduced about 21 and 24% more than that in the control, respectively. According to the results of this study, it appears that the physical REMEDIATION processes (aeration and providing optimal moisture) have an impressive role on intensifying the soil microbial activity and elimination of petroleum contaminants from soil. Therefore, the physical REMEDIATION technique can be investigated as an effective and financial method with low side effects on environment for REMEDIATION of petroleum compounds from soil.

This paper presents the results of an experimental research undertaken to evaluate different purging solutions to enhance the removal of cadmium from spiked contaminated field soil by electrokinetic REMEDIATION. Three experiments were conducted when soil was saturated with deionised water and subsequently deionised water, ammonium citrate and sodium citrate were used as purging solutions at anode end. One experiment was conducted when the soil was saturated with ammonium citrate and itself was used as the purging solution. Results showed that 49% reduction of cadmium concentration was achieved in the case of soil saturated (washed) with ammonium citrate as well as purging solution also was ammonium citrate. The soil pH and washing solutions were the most important factors in controlling the removal of cadmium in electrokinetic REMEDIATION process.

PhytoREMEDIATION is an emerging green technology that uses plants and their associated microbes to remediate different environments contaminated with various pollutants. PhytoREMEDIATION, as an effective soil REMEDIATION technology, has gained popularity in the past ten years both in developed and developing countries. The main goal of the current article is to improve the understanding of phytoREMEDIATION of organic pollutants with emphasis on hydrocarbons. To design phytoREMEDIATION systems and also enhancement of their efficiency, either in laboratory or in field experiments, there is a serious need for better knowledge of phytoREMEDIATION mechanisms and also of factors affecting phytoREMEDIATION. In addition to phytoREMEDIATION applications, advantages, and limitations, its mechanisms and related new developments have been discussed in this article.