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Electrochemical remediation for contaminated soils, sediments and groundwater
Published in Katalin Gruiz, Tamás Meggyes, Éva Fenyvesi, Engineering Tools for Environmental Risk Management – 4, 2019
Permeable reactive barriers (PRBs) have been extensively used for the remediation of inorganic and organic pollutants in groundwater. PRBs are built by digging a trench in the path of flowing groundwater and then filling it with a selected permeable reactive material. As the contaminated groundwater passes through the PRB, organic contaminants may be degraded or sequestered, inorganic contaminants are sequestered, and clean groundwater exits the PRB. Reactive materials commonly considered include iron filings, limestone, hydroxyapatite, activated carbon, and zeolite. Monitoring data from several field PRB projects showed that high-concentration dissolved inorganic species flowing through the PRB tend to precipitate and clog the reactive material. In addition, the reactivity of the material used in the PRB may decrease. Coupling electrokinetics with PRBs has been found to eliminate clogging of the PRB system caused by mineral precipitation and improve the long-term performance of PRBs. More research is needed towards developing combined electrokinetic-PRB systems to induce favorable geochemical conditions within the PRB as needed during the course of the remediation process (Weng, 2009).
1,2,3-Trichloropropane
Published in Caitlin H. Bell, Margaret Gentile, Erica Kalve, Ian Ross, John Horst, Suthan Suthersan, Emerging Contaminants Handbook, 2019
Margaret Gentile, Shandra Justicia-Leon, Sarah Page
In situ remediation approaches using zero-valent metals require the placement of reactive materials in the subsurface to contact groundwater with adequate residence time to degrade the contaminant to cleanup goals. Common approaches for placement of reactive materials include construction of permeable reactive barriers (PRBs) within a trench, in situ mixing, and injection-based placement, which may also be considered a form of PRB. Trench installation and injection-based placement are discussed here.
Adsorption of Groundwater Pollutants by Iron Nanomaterials
Published in Marta I. Litter, Natalia Quici, Martín Meichtry, Iron Nanomaterials for Water and Soil Treatment, 2018
Dimitris Dermatas, Thanasis Mpouras, Nymphodora Papassiopi, Christiana Mystrioti, Aikaterini Toli, Iraklis Panagiotakis
Soil and groundwater remediation technologies are typically classified into (a) in situ technologies or (b) ex situ technologies, based on whether contaminated soil or groundwater is treated in place or after removal, respectively. The most common in situ method is the installation of permeable reactive barriers (PRBs). PRBs are treatment zones consisting of the selected material for the decontamination, installed vertically in the flow path of a contaminated plume [4]. Ex situ remediation mainly includes different variations of the “pump and treat” method, where groundwater is extracted from the aquifer to the surface and is subsequently treated using conventional removal and/or filtration decontamination methods. Conventional removal methods are based on either photocatalytic processes, especially for degradation of organic compounds, or on chemical precipitation (hydrolysis) and coagulation processes, for removal of heavy metals. However, these processes generate large amounts of sludge that requires further treatment and are thus considered mostly ineffective, especially for the treatment of large quantities of dilute aqueous streams such as groundwater. Filtration techniques are processes that gained significant attention in recent years, but they are plagued by significant disadvantages. The very low sorptive capacity, the fact that some processes usually include precipitation as an intermediate step, and the very high cost are some characteristics that render them as non-desirable technologies in removing toxic trace elements from groundwater. The combination of targeted adsorption-based processes with the previously mentioned filtration techniques (e.g., by coating the filter sand with nanoscale iron oxides or hydroxides) has thus emerged as a viable and promising alternative for enhancing the efficiency of “pump and treat” methods, thus making them both technologically and economically effective [1].
Hydrochemical characteristics and quality evaluation of groundwater in terms of health risks in Luohe aquifer in Wuqi County of the Chinese Loess Plateau, northwest China
Published in Human and Ecological Risk Assessment: An International Journal, 2019
Xiaodong He, Jianhua Wu, Song He
Groundwater in Luohe aquifer plays a key role in local water supply. However, excessive nitrate and Cr6+ in groundwater can cause serious health risks to local inhabitants. Therefore, some necessary measures should be taken as soon as possible. For the nitrate pollution, it is crucial that less fertilizers and pesticides should be used in agriculture. The total amount of fertilization should be strictly controlled and scientific fertilization methods should be applied to reduce nitrogen loss. At the same time, domestic sewage and industrial wastes should be effectively controlled and treated. For the Cr6+ contamination, groundwater level restoration can reduce the percolation of contaminated surface water, thus reducing the contamination of Cr6+. Further, iron and its oxides have strong ability to remove Cr6+ from groundwater. The contamination of Cr6+ can be treated by chemical method. Because groundwater from private wells is rarely treated before consumption, the establishment of centralized water supply wells may be an alternative solution, particularly in the county and towns where the population is relatively concentrated. In-situ remediation technology such as the Permeable Reactive Barrier Technique (PRB) has good performance in heavy metal and nitrate removal in groundwater. Based on groundwater monitoring data, PRB can be used in water sources to prevent contamination with nitrates and Cr6+. For a long-term plan, inter-basin water transfer project may be an important program solving the water quality and water quantity problems in the semi-arid area of loess.
A tailored permeable reactive bio-barrier for in situ groundwater remediation: removal of 3-chlorophenol as a case study
Published in Environmental Technology, 2022
Efrat Miller, Ofir Menashe, Carlos G. Dosoretz
The quality of groundwater resources globally is under serious threat due to their exposure to a broad spectrum of contaminants emanating from a variety of sources including agriculture, industries and mining, among others. Therefore, it is a major task to constantly identify technologies suitable for different types of contamination. Permeable reactive barriers (PRBs) involving a reactive chemical reducing or oxidizing media are an innovative and cost-effective technology used for in situ treatment of contaminated groundwater with a record of over 200 installations worldwide [1,2]. Permeable reactive biobarriers (PRBBs), which were studied and applied to a lesser extent, are usually augmented with bacterial cultures that are adapted to target-specific contaminants, after which the biomass is seeded into a reactive zone in order to convert the contaminants into innocuous products [3–5]. The reactive media in either PRBs or PRBBs is emplaced perpendicular to the potential trajectory of the contaminated groundwater allowing the contaminated plume to passively migrate through the media under the influence of the natural hydraulic gradient. The interaction between the reactive zone and the pollutants in the plume would then lead to either abiotic transformation or biotransformation into less harmful compounds or their fixation/adsorption to the reactive material [6]. The main advantage of PRB and PRBB over other groundwater remediation technologies is that they do not require a continuous input of energy to drive the process, as contaminants are transported through the reactive zone by the intrinsic flow of groundwater. This makes, both PRB and PRBB, technically simple and economically inexpensive.
A review on groundwater contaminant transport and remediation
Published in ISH Journal of Hydraulic Engineering, 2020
P. K. Sharma, Muskan Mayank, C. S. P. Ojha, S. K. Shukla
Permeable reactive barriers (PRBs) offer a passive approach for groundwater remediation. In general, a permeable wall containing an appropriate reactive material is placed across the path of a contaminant plume (Richardson and Nicklow 2002). As contaminated water passes through the wall, the contaminants are either removed or degraded. When designing a wall, not only must an appropriate reactive medium be chosen, but also wall dimensions must be designed to assure that the entire contaminant plume will be intercepted and enough residence time within the wall will be allowed for remediation to take place.