Enhanced electrokinetic remediation (EKR) for heavy metal‐contaminated sediments focusing on treatment of generated effluents from EKR and recovery of EDTA

Abstract

Electrokinetic remediation (EKR) is one of the most successful remediation techniques to treat the sediments contaminated with heavy metals. EDTA is the most widely used enhancing agent to improve the transport process in EKR. But often the generated effluents from EKR contains a high concentration of heavy metals, which cannot be disposed of without treatment. The major objective of this study includes the estimation of optimal concentration of chelating agent EDTA, followed by treatment of contaminated sediments by EKR technique for heavy metal removal. The effluents generated from EKR were further studied for recovery and reuse of EDTA and for safe discharge of heavy metals. The optimum concentration of EDTA was found as 0.05 M with a solid-to-liquid ratio as 1:10. When fresh EDTA was used as enhancing agent the average removal of heavy metals obtained as 74.8% with EKR, whereas the application of recovered EDTA in treatment process in first, second, and third cycle showed the slight reduction of heavy metals of about 71.1%, 63.5%, and 52.1%, respectively. The heavy metal removal by recovered EDTA was effective in reduction of heavy metals up to three cycles of re-use while reducing the ecological risk in sediments. © 2020 Water Environment Federation • Practitioner points • Treatment of contaminated sediments with heavy metals achieved by electrokinetic remediation (EKR) technique enhanced with EDTA. • The recovery of EDTA and heavy metal reduction from the generated effluents during EKR treatment were performed by the addition of FeCl 3 and Na 2 PO 4, and optimized concentration was evaluated. • This study found that the use of recovered EDTA in EKR treatment has effectively reduced the risk associated with heavy metals.

Programmable Multifunctional Gels with On-Demand Patterning Capability toward Hierarchical and Multi-Dimensional Encryption and Anti-Counterfeiting

“…During the shape fixation process of the gel, the gradually penetrated Fe 3+ can help fix the gel into a temporary shape by further increasing the crosslinking density of the gel network through dynamic metal coordination bonds. During the shape recovery process of the gel, since the stability constant of the EDTA·2Na–Fe 3+ complex is much greater than that of the EDTA·2Na–Al 3+ complex, EDTA·2Na can seize Fe 3+ in the gel to restore the crosslinking state of the gel and restore the shape of the gel to its initial state. , To the best of our knowledge, there are no existing gel-based platforms with anti-swelling, anti-freezing, anti-dehydration, adjustable transparence and fluorescence, self-healing, shape memory, and fluorescence on/off switch functions (Figure b).…”

Recent Progress on Ex Situ Remediation Technology and Resource Utilization for Heavy Metal Contaminated Sediment

“…Besides, there are some other side effects appearing in EKR processes, such as thermal effects, crystallization effect, electrode corrosion reactions and so on [ 43 ]. In recent years, EKR coupled with PRB has been developed to improve efficiencies and achieve the degradation or recycling of pollutants migrating from the soil [ 45 ]. PRB embeds reactive materials that react with the contaminants to capture or degrade them.…”

Hydrothermally Stimulated Molecular Interfaces for Augmented Electron Delocalization in Wet-Chemical Phosphorus Recovery from Incineration Ash of Sewage Sludge

“…Additionally, the dissociation could be further promoted by these alkaline surfaces over SSIA particles after reacting with these free H + . These generated anionic moieties particular for tetravalent form (EDTA 4– ) can promptly coordinate with these AMs and make the formulated complexes negatively charged and dissoluble, thereby protecting free phosphate anions to survive in the extract. It is thus plausible to stimulate EDTA molecules under hydrothermal conditions, adapting to AM enclosure and P separation in the EDTA-ameliorated wet-chemical extraction of SSIA for P recovery.…”