A laboratory feasibility study on a new electrokinetic nutrient injection pattern and bioremediation of phenanthrene in a clayey soil
ABSTRACT Electrokinetic (EK) injection has recently been proposed to supply nutrients and electron acceptors in bioremediation of low permeable soils. However, effective pH control and uniform injection of inorganic ions have yet to be developed. The present study investigated a new EK injection pattern, which combined electrolyte circulation and electrode polarity reversal on a clayey soil. Soil pH could be controlled ranging from 7.0 to 7.6 by circulating the mixed electrolyte at a suitable rate (800 mL/h in this study) without any buffer. Ammonium and nitrate ions were distributed more uniformly in soil by electrode polarity reversal. The developed electrokinetic injection technology was applied primarily in bioremediation of phenanthrene contaminated soil. Over 80% of the initial 200mg/kg phenanthrene in soil could be removed in 20 d, and greater phenanthrene removal was achieved using electrode polarity reversal. Hence, the present study provides a promising electrokinetic injection technology for bioremediation of contaminated soils.
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- "The porous medium was created using soda-limesilica glass beads (Potters Ballotini Ltd, Barnsley, South Yorkshire, UK) and Speswhite kaolin (Imerys Performance Materials Ltd, Par, Cornwall, UK) to represent a model system composed of two materials with consistent properties. situ bioremediation of organic chemicals in contaminated aquifers, because it is less affected by solubility limitations (unlike oxygen) and can support the anaerobic biodegradation of a wide range of organic compounds (Spence et al. 2001; Bauer et al. 2008; Xu et al. 2010). However, the performance of bioremediation can be significantly limited due to the effect that physical heterogeneity exerts on the distribution and mixing of microbes and solutes in the subsurface (Song and Seagren 2008). "
ABSTRACT: This study investigates and quantifies the influence of physical heterogeneity in granular porous media, represented by materials with different hydraulic conductivity, on the migration of nitrate, used as an amendment to enhance bioremediation, under an electric field. Laboratory experiments were conducted in a bench-scale test cell under a low applied direct current using glass bead and clay mixes and synthetic groundwater to represent ideal conditions. The experiments included bromide tracer tests in homogeneous settings to deduce controls on electrokinetic transport of inorganic solutes in the different materials, and comparison of nitrate migration under homogeneous and heterogeneous scenarios. The results indicate that physical heterogeneity of subsurface materials, represented by a contrast between a higher-hydraulic conductivity and lower-hydraulic conductivity material normal to the direction of the applied electric field exerts the following controls on nitrate migration: (1) a spatial change in nitrate migration rate due to changes in effective ionic mobility and subsequent accumulation of nitrate at the interface between these materials; and (2) a spatial change in the voltage gradient distribution across the hydraulic conductivity contrast, due to the inverse relationship with effective ionic mobility. These factors will contribute to higher mass transport of nitrate through low hydraulic conductivity zones in heterogeneous porous media, relative to homogeneous host materials. Overall electrokinetic migration of amendments such as nitrate can be increased in heterogeneous granular porous media to enhance the in situ bioremediation of organic contaminants present in low hydraulic conductivity zones.Ground Water Monitoring and Remediation 04/2015; DOI:10.1111/gwmr.12107 · 1.25 Impact Factor
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ABSTRACT: The translationally controlled tumor protein (TCTP) displays growth-promoting and antiapoptotic properties. To gain information on the role of TCTP in cancer disease, we studied the modulation of TCTP and cell survival under stress conditions on tumor cell lines of different origins. When cancer cells were exposed to a mild oxidative stress, such low doses of Arsenic trioxide (ATO) or hydrogen peroxide (H(2)O(2)), up-regulation of TCTP was observed in cells survived to the treatment. Differently, a strong oxidative hit provided by ATO combined with glutathione (GSH) depletion or condition of glucose deprivation caused a down-modulation of TCTP followed by cell death. Clones with a forced expression of TCTP or with silenced TCTP were obtained from the breast cancer cell line MDA-MB-231. The sensitivity to oxidative stress was strongly enhanced in down-modulated TCTP cells while decreasing in cells with high levels of TCTP. Together these results indicate that TCTP is a survival factor that protects cancer cells from oxidative stress-induced cell-death. We propose TCTP as a "stress hallmark" that may be exploited as a therapeutic target to decrease the resistance of cancer cells to anticancer therapy.Experimental Cell Research 07/2011; 317(17):2479-89. DOI:10.1016/j.yexcr.2011.07.012 · 3.37 Impact Factor
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ABSTRACT: Electrochemical remediation is a promising remediation technology for soils contaminated with inorganic, organic, and mixed contaminants. A direct-current electric field is imposed on the contaminated soil to extract the contaminants by the combined mechanisms of electroosmosis, electromigration, and/or electrophoresis. The technology is particularly effective in fine-grained soils of low hydraulic conductivity and large specific surface area. However, the effectiveness of the technology may be diminished by sorption of contaminants on soil particle surfaces and various effects induced by the hydrogen ions and hydroxide ions generated at the electrodes. Various enhancement techniques have been developed to tackle these diminishing effects. A comprehensive review of these techniques is given in this paper with a view to providing useful information to researchers and practitioners in this field.Journal of hazardous materials 08/2011; 195(52):11-29. DOI:10.1016/j.jhazmat.2011.08.047 · 4.33 Impact Factor