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... References are listed under either the "General" subsection or sub-sections specific to the respective section or sub-section headings. Moreover, many handbooks, special publications, and textbooks covering a great variety of remediation technologies such as Freeze and Cherry (1979), U.S. EPA (1985), LaGrega et al. (1994), National Research Council (1994), Wilson and Clarke (1994), Evans (1997), Otten et al. (1997), Suthersan (1997), Sellers (1999), Reddi and Inyang (2000), Hyman and Dupont (2001), Rowe (2001), Stegmann et al. (2001), Yong (2001), Lehr et al. (2002), Boulding and Ginn (2004), Nathanail and Bardos (2004), Sharma and Reddy (2004), Hudson (2006), Domínguez (2008), Dubois (2008), Khire et al. (2008), Nemerow et al. (2009), etc. are included in the sub-section "General" in the references to provide a wealth of information for researchers and practitioners interested in the subject. ...
... Moreover, acidic waste can be neutralized. The process is applicable to metals, PCBs, oils, and other organic compounds (Sharma and Reddy 2004). Extensive dewatering of wet sludges and waste is typically unnecessary as water is required for cement hydration. ...
... Unburned carbon in fly ash may sorb organics from the waste. As a result, a pozzolan such as fly ash may have beneficial effects in the stabilization of both organic and inorganic wastes (Sharma and Reddy 2004). ...
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![Albert T. Yeung]()
Contaminated sites can pose a significant risk to public health and the environment. Many different insitu or ex-situ remediation technologies have been developed throughout the years to mitigate the risk imposed by soil contamination. These technologies may be contaminant and site specific. Remediation can be achieved by contaminated soil removal, contaminant removal, containment, stabilization/solidification, transformation, or different combinations of these mechanisms. It may also be necessary to apply these technologies in combination to achieve remediation goals, in particular, for cases of contamination by multiple contaminants. Some of the remediation technologies currently available are presented in this invited lecture, in particular, the theory, state of development, applicability, limitations, remediation efficiency, cost effectiveness, and potential side effects of the remediation technologies are presented. Details of performance monitoring are described, criteria on selection of the appropriate remediation technology are given, and remediation cost estimate procedure is outlined. As innovative remediation technologies are being developed continuingly to satisfy various needs, the technologies presented in this invited lecture are by no means exhaustive. Nonetheless, a comprehensive list of references is given for readers interested in particular technologies to conduct their further exploration.
... Their interaction with the porous media is a dynamic process that includes diffusion, advection, occlusion, precipitation/dissolution, and degradation. Consequently, these substances may pollute groundwater reservoirs immediately or as a long term source; or may also be chemically or biologically altered depending on existing subsurface conditions (Sharma and Reddy 2004). These processes have significant influence on remediation techniques during the removal of organic and inorganic contaminants from soils and groundwater (Suthersan 1997). ...
... The time, or pore volume of flow, needed by the center of mass of the contaminant to pass through a soil column or reactive barrier, respect to the time or volume expected for non-reactive transport (diffusion + advection) defines a retardation factor (R). This retardation factor can be directly incorporated in equation (16) resulting (Sharma and Reddy 2004): ...
... The barrier is designed to reduce the initial concentration C 0 , to effluent concentrations C f . The thickness of the wall will depends on the flow velocity, given that advection controls the mass transport through PRB, and on the residence time required to reach the target concentration (Sharma and Reddy 2004) ...
Presence of organic and inorganic contaminants in soils impacts soil and groundwater quality. The hydraulic conductivity of porous media controls the displacement of liquids in the soil pores and affects the fate and transport of contaminants in the environment. This chapter presents the influence of relevant soil and permeating liquid properties on liquid displacement and mass transport in soils including diffusion, advection, retardation, reaction, solubilization and immiscible flow. Then, we address the relevance of micro-heterogeneities on the displacement and generation of ganglia during the simultaneous flow of water and non-aqueous phase liquids (NAPL). Finally, we discuss the importance of soil hydraulic conductivity and mass transport mechanisms in relation to geoenvironmental applications such as permeable reactive barriers (PRB), soil liners (SL) and smart permeable reactive barriers (SPRB).
... Various methods are available for treating soils contaminated with heavy metals, including landfilling (excavating and hauling), containing pollutants via capping/subsurface barriers, solidification/stabilization, vitrification, soil washing/flushing, electrokinetic treatment, and bioremediation. Deciding to use a particular method is a based on several variables, including the size of the project, cost of treatment, effectiveness, time frame, required monitoring, environmental impact, and processing steps, to name a few (Sharma and Reddy 2004). ...
... Excavating and physically removing the soils is perhaps one of the oldest methods for treating contaminated soil. Its advantages include the complete and rapid removal of contaminants (Wood 1997;Sharma and Reddy 2004). Disadvantages of excavation and hauling include simply moving the contaminated waste to a different location. ...
... Stabilization and solidification (S/S) uses additives or processes to chemically bind and immobilize contaminants or to microencapsulate the contaminants in a matrix that physically prevents mobility (USEPA 1986;EPRI 2003;Sharma and Reddy 2004). Stabilization typically refers to a chemical process that actually converts the contaminants into a less soluble, mobile, or toxic form. ...
- Marat Goldenberg
- Krishna R. Reddy
The Matthiessen and Hegeler Zinc smelting site in Illinois was designated as a Superfund site in 2005 for its high concentration of heavy metals. Through multiple comprehensive field investigations, the Illinois EPA collected soil and sediment samples from the site and the adjacent residential community. Among other contaminants, zinc was found to be present at elevated levels in all samples, and cadmium and lead were elevated in all but one sample. The large surface area of the contaminated site, more than 40 hectares (100 acres), poses a challenge for treatment. Two alternative treatment methods were evaluated for long-term sustainability: the traditional method of excavation, hauling, and disposal in a hazardous waste landfill and an in situ remediation approach via solidification/stabilization. The life cycle assessment for each alternative was performed using SimaPro for energy inputs and environmental releases through all stages of manufacturing of materials needed for remedial operations, transportation, and remedial implementation. It was found that due to the large quantity of contaminated soil that is required to be excavated and hauled to the nearest landfill, the in situ method of solidification/stabilization was the more sustainable option in the long term. Other aspects associated with sustainability include social and economic impacts; both are discussed in the remedial options.
... The adsorption of a metallic ion depends on its relative preference to form strong bonds (inner sphere complexes) with the soil surface. In this process, ionic or molecular constituents travel in the direction of their concentration gradients (Sharma and Reddy 2004). ...
... Generally, at equilibrium, the concentration of the contaminated solution is a function of the concentration in the solid phase only and adsorption of chemical on the clay surface dominates the reaction (Acar and Haider 1990). In such situations, the partition coefficient K p = K d (Sharma and Lewis 1994). In case local equilibrium assumption is not valid, it is assumed that the sorption process is represented by a firstorder reversible kinetic reaction (Ghosh et al. 2014). ...
... Adsorption increases with pH and the presence of soil organic matter decreases the uptake rate in the presence of competing cations or dissolved organic ligands in the solution (Banks et al. 2006). Linear, Langmuir and Freundlich isotherms are followed usually to describe this adsorption behaviour of chromium on solid phases (Sharma and Reddy 2004). ...
Hexavalent chromium (Cr6+) is released in the lithospheric environment through leachate pollution in chrome tanning industries. Transportation of Cr6+ containing plume through soil needs to be assessed by estimation of some mechanistic parameters such as diffusion coefficient (D), distribution coefficient (K d) and retardation factor (R). An investigation was undertaken with three soil samples, S1, S2 and B, to examine their potential use as liner material for controlling Cr6+ pollution in soil environment. Batch adsorption kinetic test was carried out to estimate the K d and R values of soil samples S1 and S2. A numerical solution technique was adopted for prediction of such transport parameters in simulated field condition using the finite difference method (FDM). The efficacy of the present numerical solution technique (FDM) is compared with subsequent column experiment data with Soil-B along with the analytical solution. It was observed that the experimental value of "D = 3.04 × 10−8 m2/s for Soil- B" by using the applied technique closely fitted to that value evaluated by the analytical method (r 2 = 0.98). The values of 'K d' for Soils S1 and S2 were found to be 0.008 and 0.021 mL/g, respectively, using batch adsorption. The values of 'R' of the soil samples S1 and S2 were obtained as 1.037 and 1.053, respectively. All the above results were obtained in correspondence to the initial hexavalent chromium concentration level of 7.5 mg/L in the simulated leachate sample.
... Heavy metal contaminated soils have been the target of many remediation studies because these contaminants are very common at contaminated sites. Different methods and technologies commonly used for the remediation of heavy metals include pump and treat, in situ flushing, soil washing, electrokinetic remediation, permeable reactive barriers, stabilization and solidification, vitrification, and monitored natural attenuation (Sharma and Reddy 2004). High energy consumption, the use of chemicals and long treatment time make these technologies very expensive and impractical for the remediation of mine areas and mine tailings. ...
... The use of atmospheric oxygen has also been proposed in an attempt of improve the oxidation with a minimum use of chemicals (Davies et al. 2016). Permeable reactive barriers (PRB) is an interesting technology for the treatment of mine water, especially, contaminated groundwater (Sharma and Reddy 2004). The basic idea of this system is the construction of a buried barrier that intercepts the flow of groundwater. ...
... The limitations of passivation technology are related with the high cost of the treatment and the stability and duration of the coating, which are difficult to define and largely depend on the environmental conditions. Solidification/stabilization (S/S) and vitrification are remedial technologies that tend to immobilize contaminants in the original location instead of being degraded, destroyed or removed (Sharma and Reddy 2004). Contaminants, i.e. heavy metals, are confined and immobilized. ...
Mining practices and the absence of proper mine land reclamation has led to heavy metal contaminated sites with serious impact on the ecosystems and risk for human health. The origin of the contamination is often associated to mine tailing deposits because they are a source of the acid mine drainage (AMD). These areas are devoid of vegetation due to the harsh soil conditions that prevent the rooting of plant species. The remediation of these areas followed by revegetation is necessary to suppress the generation of the AMD and its negative effects on the ecosystems. Conventional remediation technologies for heavy metal contaminated sites are usually not applicable because of the high cost associated with chemicals and energy requirements, as well as the long treatment time to remediate large areas. In this study, the use of phytocapping for the remediation of mine tailing deposits and abandoned mine areas is reviewed. Phytocapping is cost effective, environmentally friendly and has multifunctional role against various problems of mine tailings: it provides erosion control, landscape rehabilitation, enhances the soil properties for further colonization of other more demanding vegetal species, reduces the leachability of metals downwards the groundwater, and favors the immobilization of metals forming less bioavailable species. The most critical step in phytocapping is the developing of the first vegetative cover because of the biotoxicity of the mine soil and mine tailings. Several amendment materials can be used to ameliorate soil conditions creating a favorable environment for the rooting of plants, as well as serving as a source of nutrients. Local plant species with fast growing are preferable because their adaptation to the soil and climate conditions favors their self-propagation.
... The adsorption of a metallic ion depends on its relative preference to form strong bonds (inner sphere complexes) with the soil surface. In this process, ionic or molecular constituents travel in the direction of their concentration gradients (Sharma and Reddy 2004). ...
... Generally, at equilibrium, the concentration of the contaminated solution is a function of the concentration in the solid phase only and adsorption of chemical on the clay surface dominates the reaction (Acar and Haider 1990). In such situations, the partition coefficient K p = K d (Sharma and Lewis 1994). In case local equilibrium assumption is not valid, it is assumed that the sorption process is represented by a firstorder reversible kinetic reaction (Ghosh et al. 2014). ...
... Adsorption increases with pH and the presence of soil organic matter decreases the uptake rate in the presence of competing cations or dissolved organic ligands in the solution (Banks et al. 2006). Linear, Langmuir and Freundlich isotherms are followed usually to describe this adsorption behaviour of chromium on solid phases (Sharma and Reddy 2004). ...
... Sites contaminated with organic pollutants can be remediated with technologies such as soil vapor extraction, soil washing, stabilization and solidification, electrokinetic remediation, thermal desorption, bioremediation, in situ chemical oxidation, phytoremediation, pump and treat, in situ flushing, permeable reactive barriers, in situ air sparging, and monitored natural attenuation (Sharma and Reddy 2004). However, some of these methods are only applicable to specific organic contaminants. ...
... Many studies have explored the phytoremediation potential of various plants on both organic and inorganic contaminants, the plant species that are best able to remediate certain contaminant classes, and effective methods to enhance phytoremediation. Contaminants that can be targeted for phytoremediation include heavy metals (Robinson et al. 1998;Bolan et al. 2003;Pulford and Watson 2003), radioactive nuclides (Lee and Yang 2010;Singh et al. 2008), other inorganic contaminants such as arsenic, selenium, antimony and tellurium (Greger et al. 2014;Ogra et al. 2015), explosives (Medina and McCutcheon 1996;Bhadra et al. 2001;Rylott and Bruce 2009;Van Aken 2009), crude oil and oil products (Nedunuri et al. 2000;Pichtel and Liskanen 2001;White et al. 2005;Merkl et al. 2005;Ramamurthy 2012), pesticides (Schnoor et al.,1995;Chaudhry et al. 2002), PAHs (White et al. 2005;Huesemann et al. 2009), and PCBs (Sharma et al. 2015). A few select studies on phytoremediation of heavy metals or organic contaminants are reviewed below to create an understanding of the mechanisms of the phytoremediation of these contaminants when each type of contaminants exists individually. ...
Soil pollution is a major environmental problem and many contaminated sites are tainted with a mixture of organic and heavy metal contaminants. Compared to other remedial strategies, phytoremediation is a low cost, environmentally-friendly, sustainable means of remediating the contamination. This review first provides an overview of phytoremediation studies where the soil is contaminated with just one type of pollutant (heavy metals or organics) and then critically evaluates the applicability of phytotechnologies for the remediation of contaminated sites where the soil is polluted by a mixture of organic and heavy metal contaminants. In most of the earlier research studies, mixed contamination was held to be detrimental to plant growth, yet there were instances where plant growth was more successful in soil with mixed contamination than in the soil with only individual contaminants. New effective phytoremediation strategies can be designed for remediation of co-contaminated sites using: (a) plants species especially adapted to grow in the contaminated site (hyperacumulators, local plants, transgenic plants); (b) endophytic bacteria to enhance the degradation in the rizhosphere; (c) soil amendments to increase the contaminants bioavailability [chelating agents and (bio)surfactants]; (d) soil fertilization to enhance the plant growth and microbial activity in the soil; and (e) coupling phytoremediation with other remediation technologies such as electrokinetic remediation or enhanced biodegradation in the rhizosphere.
... Several different technologies have been developed to remediate soils, sediments, and groundwater based on physicochemical, thermal, and biological principles ( Sharma and Reddy, 2004 ). However, they are often found to be costly, energy intensive, ineffective, and could themselves create other adverse environmental impacts when dealing with diffi cult subsurface and contaminant conditions. ...
... The basic purpose of electrokinetic barriers is to prevent the migration of contaminants from its current location. These barriers are similar to traditional passive containment barriers (such as vertical slurry walls) for soil and groundwater pollution containment and active containment barriers (such as pumping systems and drainage systems) for groundwater pollution containment ( Sharma and Reddy, 2004 ). Such barriers are often used as an interim measure prior to implementing a permanent treatment system. ...
... At large landfills, the collected gases (passive or active gas collection) are used for energy recovery. Landfill gas recovery systems can reduce landfill gas odour and migration, and the danger of explosion and fire, and may be used as a source of revenue that may help to reduce the cost of closure (Sharma and Reddy, 2004). ...
... The mixed contaminants include combinations of organic compounds, heavy metals, and radionuclides. Very few conventional techniques are found to address the remediation of such mixed contaminant sites (Sharma and Reddy, 2004). Moreover, these techniques are ineffective or expensive to remediate mixed contaminated sites that contain low permeability and heterogeneous soils. ...
... There are several alternatives for the remediation of groundwater including chemical oxidation, precipitation, coagulation, adsorption, biological degradation, permeable reactive barriers, etc (Sharma and Reddy 2004). ...
... The advection-dispersion-retardation model allows calculating the contaminant concentration change, according to (Sharma and Reddy 2004): ...
Contaminant transport in non-reactive porous media depends on soil and pore fluid properties. In the case of fine soils, chemical reactions, electrostatic interactions and biomediated reactions can modify the physical properties of the porous media. This work evaluates mass transport through reactive barriers, showing the relative importance of particle-fluid interactions and microorganism growth on contaminants displacement. Compacted soils samples were tested with arsenic solutions and landfill leachate as permeating liquids. The addition of clay decreased the hydraulic conductivity and delayed the contaminant displacement due to electrostatic attraction between the charged soil particles and counter ions. Microorganisms were responsible for pore clogging due to the increase of biomass with permeation time. These two effects were simultaneously considered by implementing a 1D-mass transport equation to simulate the behaviour of reactive barriers. Obtained results are of fundamental importance for the design of "smart" barriers for the remediation of contaminated groundwater. transporte 1D para simular el comportamiento de las barreras reactivas. Los resultados obtenidos son de fundamental importancia para el diseño de barreras "inteligentes" para la remediación de sitios contaminados.
... La teneur en matière organique f oc joue un rôle très important sur l'aptitude du sol à retenir momentanément ou à fixer les polluants. L' adsorption des composés organiques dans un sol est principalement liée à la fraction en matière organique du sol (Sharma et Reddy, 2004). ...
... Les informations concernant la structure du sol peuvent être utilisées pour délimiter la forme et la distribution des contaminants dans le sol. Selon Sharma et Reddy (2004), la structure du sol peut aussi affecter le transport et la rétention des contaminants. ...
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![Otmane Boudouch]()
L'extraction sous pression réduite est l'une des techniques de dépollution envisageables lorsqu'il y a contamination d'un sol par des composés organiques volatils (COVs). Cette technique consiste à créer une dépression dans le sol et induire un écoulement contrôlé d'air qui entraînera les contaminants volatils dans la phase gazeuse extraite. Les objectifs de ce travail peuvent se résumer de la façon suivante : - caractérisation de la méthode la plus adaptée à déterminer les deux composantes, horizontale et verticale, de la perméabilité à l'air.- étude de l'évolution de la perméabilité à l'air du sol en fonction du degré de saturation de celui-ci en liquides. - vérification de la validité ou non de l'utilisation des colonnes unidirectionnelles dans le dimensionnement des systèmes d'extraction en se basant sur l'atteinte d'une vitesse critique de l'air au sein des pores du sol. Pour accomplir ces objectifs, un pilote d'essai a été conçu et réalisé, plusieurs expériences ont été effectuées et des modèles de la littérature ont été utilisés. Les résultats obtenus ont montré que la méthode la plus adaptée à la détermination de la perméabilité à l'air du sol est celle mettant en œuvre un régime stationnaire sans couverture à la surface du sol, Et que les résultats obtenus dans une colonne unidirectionnelle concernant la vitesse critique ne peuvent être extrapolés à l'échelle du terrain comme il se fait actuellement.
... Landfill liners must have a low hydraulic conductivity to control leachates originating from the wastes and the susceptibility of the hydraulic conductivity to changes with time or exposure to chemicals or leachates is one major factor in the selection of liners for use in a landfill (Koch 2002;Abichou et al. 2004;Yılmaz et al. 2008). U.S Environmental Protection Agency Subtitle D regulations as well as other state agencies specify that landfill liners made of either compacted clay or artificially synthesized seals should be designed or required to have a hydraulic conductivity of less than or equal 10 -7 cm/s (Sharma and Reddy 2004). To fulfill this recommendation Qian et al. (2002) stated that certain characteristics of soil material should be met. ...
Crushed shales obtained from two locations (Ahoko, Bida basin and Ifon, Dahomey basin) in Nigeria were evaluated to determine their suitability as compacted landfill liners. The shale samples were subjected to X-ray diffraction, hydraulic conductivity, classification, compaction, consolidation and cation exchange capacity tests. The result of the XRD revealed kaolinite and illite as the major clay minerals while quartz was the dominant non-clay minerals. The average CEC of Ifon and Ahoko shales was 5.37 and 8.34 mEq/100 g, respectively. The liquid limit, plastic limit and plasticity index of crushed Ifon shales ranged from (33.9 to 37.4%), (25.2 to 27.2%) and (8.6 to 10.2%) while the Ahoko shales ranged from (44 to 46.4%), (26.3 to 27.4%) and (16.6 to 19.6%), respectively. In addition, the estimated activity of the clay fractions of the two shales ranged from 0.41 to 0.51, suggesting inactive clays. The compacted shales have low compressibility and when compacted at modified Proctor level of compaction. At molding water content between optimum moisture content (OMC) ±2%, the hydraulic conductivities of the compacted shale were in the order of 10⁻⁶–10⁻⁷ cm/s when compacted at modified Proctor level. At OMC, hydraulic conductivities of the compacted shales were in the order of 10⁻⁷ cm/s when exposed to different concentration of calcium chloride solutions. Overall, the crushed shale samples from Ahoko and Ifon generally fulfilled the basic geotechnical properties for compacted clay liners.
... If it is not controlled in the biological treatment process, it is possible not to break down organic pollutants occur fully, leading to obtain products more toxic and that can have a greater ability to move from primary pollutants [11]. ...
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![Huda Abbas Mohammed]()
This research is interested in using the two species of fungi such as Penicilliumexpansm and Aspergillusniger for Biodegradation of Safranin dye as industrial and Carcinogenic dyes,The results showed that P.expansum was the more efficient from Asp. niger in Biodegradation of the Safranin dye. The percentage of Bio decolonization about 41.035% during incubation at 120 hours, while when use Asp. nigerthe percentage of Bio decolonization was about 38.952% during same time of incubation.
... Metal polluted sites have become a growing environmental problem in most countries around the world due to anthropogenic activities. The greatest emissions of metals occur during production of other metals such as steel and iron, and from combustion of fossil fuels (Sharma and Reddy 2004). Some metals, like zinc (Zn), copper (Cu), manganese (Mn), nickel (Ni) and cobalt (Co), are micronutrients necessary for plant growth. ...
We examined exudation of low molecular weight (LMW) organic compounds of ectomycorrhizal (ECM) and non-mycorrhizal (NM) seedlings in relation to metals. Scots pine seedlings, either colonized by one of six different ECM fungi or NM, were grown in Petri dishes containing glass beads and liquid growth medium and exposed to elevated concentrations of Pb, Cd and As. Exudation of LMW organic compounds (LMW organic acids (LMWOAs), amino acids and dissolved monosaccharides) and dissolved organic carbon (DOC) was determined qualitatively and quantitatively and exudation rates were calculated. Metals had a significant impact on exudation, especially of oxalate. For Pb and Cd treatments, exudation of oxalate and total LMWOAs generally increased by 15–45% compared to nutrient controls. Production of amino acids, dissolved monosaccharides and DOC was not significantly stimulated by exposure to metals; however, there were non-significant trends towards increased exudation. Finally, exudation generally increased in the presence of mycorrhizal seedlings compared to NM seedlings. The results suggest that ECM fungi may reduce the toxicity of metals to plants through significant increases in the production of organic chelators. Axenic conditions are required to assess the full potential for production of these molecules but their overall significance in soil ecosystems needs to be determined using additional experiments under more ecologically realistic conditions.
... It comprises of a liner system, leachate collection and treatment system, groundwater monitoring system, gas extraction system and a cap system. Movement of leachate, landfill gas and limited access of vectors like rodents and flies are completely controlled ( Sharma and Reddy, 2004 ). ...
Selection of a landfill site in an urban area like Srinagar is a captious issue due to the involvement of multitude of parameters. The decisive parameters are of environmental, economic and social in nature, some of them conflicting, which makes landfill site selection a tedious and complex process. This study focuses on the identification of potential landfill sites in Srinagar city based on Geographic Information System (GIS) and Remote Sensing; using techniques such as Multi Criteria Evaluation (MCE) and Analytic Hierarchy Process (AHP). Selection of landfill site by the integration of GIS and MCE can be an efficient technique which simultaneously pays attention to all restrictions. GIS has the capability to handle and simulate the necessary constraints while MCE makes it possible to generate and rank the alternatives according to their attractiveness. Five potential sites are identified which fulfil MoEF and CPCB guidelines Land Suitability Index (LSI) is used to find the extent of suitability of different sites on the basis of environmental considerations while Total Hauling Distance (THD) is used for evaluating sites from economy point of view. The results obtained showed that 98.69% of the study area is restricted. Weights are calculated by AHP using 45 pairwise comparisons with Consistency Ratio equal to 3.2%. Cartographic analysis is performed using ESRI ArcGIS 10.5 software.
... The loss on ignition (LOI) is also high. The silica amount is less than typical values for non-saline soils (Sharma and Reddy 2004). However, the calcium and magnesium oxides are higher than typical values for non-saline soils. ...
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![Yahia E.-A. Mohamedzein]()
- Amer Ali Al-Rawas
Sabkha soils are salt-bearing formations that are formed in arid regions. In their in situ states the sabkha soils have high compressibility and low shear strength. These soils are also heterogeneous and their properties depend on the type and amount of salt present. Thus, these soils are not suitable for support of infrastructures without the risk of high settlement and/or bearing capacity failure. This paper investigates the possibility of using cement to improve the shear strength of sabkha soils for possible use as a foundation-bearing soil. The sabkha soil used in this study is a sandy sabkha obtained from the coastal plains at Al-Auzayba, Sultanate of Oman. Cement was added in percentages of 2.5, 5, 7.5 and 10%, by dry weight of soil. The soil-stabilizer mixers were allowed to cure for 7, 14 and 28 days. Laboratory tests such as compaction, unconfined compression, consolidated undrained triaxial and durability tests were performed to measure the engineering characteristics of the stabilized material. The results showed substantial improvements in the shear strength of the sabkha–cement mixtures and the mixtures are also durable with small weight loss after 12 wetting/drying cycles. Thus, cement can be used to improve the shear strength of sabkha soils. Furthermore, the effective stress path and the tress-strain relation of the sabkha–cement mixtures follow trends similar to those of cemented calcareous soils.
... Para la remediación existen numerosas alternativas, muchas de ellas con registro de propiedad, las cuales incluyen desde la excavación, transporte y gestión en vertedero del suelo, incineración, biodegradación, fitoremediación, lavado y tratamiento, confinamiento, estabilización y solidificación, vitrificación, etc. (Sharma y Reddy, 2004). En todos los casos la selección del método apropiado depende de condiciones técnico-económico-ambientales, las cuales se encuentran limitadas por condicionantes particulares de cada sitio. ...
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![Franco M. Francisca]()
La estabilización/solidificación (E/S) es una de las técnicas más utilizadas para remediar suelos contaminados. El comportamiento obtenido en las mezclas depende en gran medida de los contenidos de contaminante, cementante y tipo de suelo. En este trabajo se presentan resultados experimentales de estabilización de un suelo limoso de origen loéssico contaminados con hidrocarburos. Para la estabilización se utilizan distintos contenidos de cemento Portland, determinando en cada caso la conductividad hidráulica y la resistencia a la compresión simple de la mezcla de limo-hidrocarburo-cemento solidificada. Los resultados obtenidos muestran que la caída de resistencia producida por el contaminante orgánico es muy importante en este tipo de suelo. En general, los suelos estabilizados y solidificados alcanzan sólo un 20% de la resistencia determinada para el suelo limpio. Además, la conductividad hidráulica se incrementa significativamente por la presencia de la fase orgánica ya que restringe el acceso del cemento a las superficies de las partículas del suelo. Las muestras contaminadas y estabilizadas resultaron aproximadamente un orden de magnitud más permeables que el mismo suelo sin hidrocarburo.
... Thus, hydraulic barriers (i.e., diaphragm walls, soil-bentonite vertical cutoff walls, soil-cement-bentonite vertical cutoff walls) can also be applied to prevent transport of contaminants in an aquifer as well as to prevent seawater intrusion (Anderson and Mesa, 2006;Luyun et al., 2011). In groundwater remediation projects, these vertical hydraulic barriers are also used extensively to control the migration of contaminants in groundwater so that contaminated groundwater can be treated by in situ remedial technologies (Sharma and Reddy, 2004;Malusis et al., 2009;Du et al., 2015aDu et al., ,b, 2016. For example, Du et al. (2015a,b) proposed a new type of soil-bentonite vertical cutoff wall comprising a clayey soil and calcium bentonite materials for containing contaminants in the groundwater. ...
... Therefore, L 0 = 138 kg/m 3 can be obtained according to the LFG density q g (1.23 kg/m 3 ) and the average MSW density q MSW (1 Mg/m 3 ) [29]. Note that bioreactor landfills use enhanced microbiological activities to transform and stabilise the biodegradable fractions of MSW at a faster rate than traditional landfills [30]. As described by Faour et al. [13] and Meima et al. [31], a higher value of c 0 can be expected in bioreactor landfills. ...
Recovery and utilisation of landfill gas (LFG) can not only reduce the greenhouse effect but also permit the generation of electricity. A good understanding of gas migration from the waste body to the LFG extraction system is required to permit efficient gas recovery. This paper presents an analytical two-dimensional gas flow model to predict the distribution of gas pressure, the CH4 emission flux, the distance of influence and recovery efficiency in landfills. The model is indicative of the flow towards a combined extraction system of vertical wells and horizontal gravel-filled trenches. Moreover, the model has a horizontal layered structure to accommodate anisotropy of municipal solid waste (MSW) and vertical variations in both gas generation rate and permeability. The relevant governing equations for multiple homogenous layers were combined using continuity conditions of gas pressure and flux at the layer interfaces, subjected to realistic boundary conditions, and then solved using an eigenfunction expansion approach. The solution was compared with data available in the literature, and a parametric evaluation was performed to understand the roles of the relevant variables. The results show that, for a non-homogeneous model, the maximum pressure appears at the upper layer of the landfill rather than at the bottom. The location of the maximum pressure depends on the assumptions regarding the vertical distributions of the LFG generation rate and permeability. Additionally, the results can be used to form preliminary estimates of LFG recovery efficiency and overall landfill stability for different waste compositions.
... This collapse causes an increase of the hydraulic conductivity and a decrease of the osmotic swelling. These two effects increase the flux of contaminants [66,43,83]). ...
- Gemmina Di Emidio
- J. Meeusen
- D. Snoeck
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![Daniel Verastegui]()
Issues associated with the production of waste and their disposal continue to be a major preoccupation for governments, public and private organizations and the general community around the world. This paper includes the current trends on the possible reuse of various waste streams for geotechnical and geo-environmental applications. After a general overview, specific examples will be described and new results on amended recycled sediments and amended soils will be presented. Examples of this sustainable concept to be further promisingly developed include: (1) the possible use of waste heat for the production of new amended raw materials, (2) the reuse of dredged sediments for various geotechnical and geo-environmental applications, (3) the use of various recycled soil amendments for mechanical and hydraulic enhancement techniques.
... In early studies in 1920s and 1930s the interaction of clay and organic compounds cut attention and prevailed among different subjects (Merinska et al., 2002). Sharma and Reddy (2004) called organoclay as an artificially engineered substance and studied its applications in landfills. Jayns and Boyd (1991) and Smith and Jaffe (1994) examined the ability of conventional clay and modified clay to preserve hazardous and pathogenic microbes, and toxic substances. ...
BTEX is one of the hazardous organic contaminants available in produced water. Since it has high toxicity, and causes numerous environmental problems, it should be removed up to a limit complying with environmental standards. The objective of this study is to analyze the feasibility of BTEX removal, as the oil pollution index, from produced water by using organoclay as the adsorbent of oil contaminants compared to typical clay. To produce organoclay, CTAB surfactant was used and tested with different cation capacities. The obtained results reveal that organoclay, due to its microstructures, high effectiveness, simplicity, and low cost, is a viable solution to expensive and complicated systems for BTEX removal. Furthermore, organoclay is capable of adsorbing 95.6% BTEX from produced water in the order of ethylbenzene, xylene, toluene, and benzene, respectively.
... This collapse causes an increase of the hydraulic conductivity and a decrease of the osmotic swelling. These two effects increase the flux of contaminants [66,43,83]). ...
The aim of this Specialized Lecture is to present the recent advances and issues, as well as original research, on Modified Clays for Barriers. Topics of interest include: (1) long-term hydraulic performance of modified clays for GCLs, (2) chemico-osmotic and diffusion efficiency of modified clays, (3) modeling coupled chemical-hydraulic-mechanical behavior of modified clays, (4) wet and dry ageing of modified clays, (5) use of novel bentonites for vertical barrier applications, and (6) organoclays for various barrier applications. In addition, the possible reuse of dredged sediments after polymer treatment will also be discussed. Environmental management and handling of dredged sediments are important worldwide because enormous amounts of dredged material emerge from maintenance, construction and remedial works within water systems. Usually these materials after temporary upland disposal in lagoons are disposed in landfills. The aim of this study is to analyse the possible reuse of these sediments as a low-cost alternative material for landfill covers. The mechanisms through which polymers can improve the efficiency of dredged sediments for waste containment low permeable barriers are discussed.
... En muchos casos, la disposición final de estas sustancias en el ambiente provoca la contaminación del aire, agua y suelo, por lo que se transforman en una problemática geoambiental. Estos contaminantes afectan el ecosistema y eventualmente tienen un impacto adverso en la salud de los hombres y en el ambiente (Sharma y Reddy 2004). ...
This chapter aims to offer an overview of the main remediation methods of potentially toxic elements in contaminated soils, mainly heavy metals, metalloids and radionuclides, focusing on their essential characteristics, advantages and limitations. It consists of two main groups of technologies: the first group dealing with containment and confinement, minimizing their toxicity, mobility and bioavailability. Containment measures include covering, sealing, encapsulation and immobilization through solidification (cement-based, polyethylene and resine binders, bituminization or asphalt batching and vitrification or glassification) and stabilization with inorganic and organic amendments. The second group, remediation with decontamination is based on the remotion, clean up and/or destruction of contaminants. This group includes mechanical procedures (excavation, transport and disposal to landfills), physical separations, chemical technologies such as soil washing with leaching or precipitation of potentially toxic elements, soil flushing, thermal treatments (desorption, pyrometallurgical processes and incineration) and electrokinetic technologies (electromigration, electroosmosis, electrophoresis and combinations of electrokinetics with other techniques). There are also two approaches of biological nature: bioremediation (biosorption, bioreduction, biomineralization and bioleaching-with some examples from Korea) and phytoremediation (phytoextraction, including chelate-assisted phytoextraction, phytostabilization, phytoremediation in mining activities -with examples from Portugal, Spain, Ecuador, Peru and Chile mainly-, phytovolatilisation and phytomining).
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![Ahmed M.A. Nasr]()
Sabkha soils are found in many parts of the world, particularly in arid and semi-arid areas. The sabkha soils have high compressibility and low shear strength. Thus, these soils are not suitable for support of structures and infrastructures without the risk of high settlement and bearing capacity failure. Therefore, the purpose of the present study is to evaluate the geotechnical characteristics of sabkhas sediments from different sites along the Egyptian–Libyan coast. In addition, the study aimed to investigate the geotechnical characteristics of treated sabkha sediments with different dosages (5, 10, 15, 20, and 25 %) of cement kiln dust CKD. Sabkha samples were collected from four different sites along the Egyptian–Libyan coast where they could best represent different sabkha types of these areas. Laboratory tests such as chemical analyses, X-ray diffractometer, index properties, compaction, unconfined compressive strength, and consolidation tests were performed. The results showed that the salt constituent plays an important role in determining the engineering properties of sabkha soil. There is a noticeable strength improvement in sabkha soils with low salinity as compared to those with high salinity. Furthermore, the results showed significant improvement in strength during the first 14 days of curing which was sufficient for the completion of the major reactions between the CKD and the sabkha soils. The addition of 20 % CKD was sufficient to reduce the compression index, CC, by about 17–45 % according to the type of sabkha and salinity concentration.
Electrokinetic remediation is one of the methods for cleaning of soil and sediments. In this case, by applying a weak electric field using the external power supply, the pollutants are separated from the soil or sediment by various mechanisms, especially electrical migration. But due to the cost of supplying electricity, it is not affordable. On the other hand, in the microbial fuel cells, bacteria release electrons by consuming organic matter and producing an electric current. Therefore, in this study, microbial fuel cells process with three different electrodes at the anode and combination with granular activated carbon was used to produce a green weak electric field. Based on the electrical migration mechanism, the removal rate of hexavalent chromium from marine sediments was evaluated by combining three physical, chemical, and biological processes. The results showed that the amount of power produced is significantly dependent on the type of the anode electrode used as the graphite electrode combined with activated carbon granule due to better substrate conditions for bacterial attachment as well as higher electron transfer rate to the electrode. In this study, the highest amount of power density of 10 ± 0.02 W / m3 was obtained. Under these conditions, the highest chromium removal rates were about 64 to 73% in the cathode and anode regions, respectively. In general, it can be concluded that the use of bioactive carbon can improve the production capacity of microbial fuel cells in cleaning marine sediment polluted to heavy metals.
The growth in the economic development of all the sectors have put an immense pressure on natural resources and have caused great turmoil to the soil cover which is under great stress due to surplus addition of heavy metals or toxic compounds via various sources of natural as well as anthropogenic origin. It is the need of time to find a sustainable solution to remediate the soil and to regain its fertility. Amongst many proposed technologies phytoremediation proves to be quintessence for a sustainable solution. Hence, various aspects of phytoremediation and its significance in truncating the problem are discussed here.
This work investigates the influence of electrokinetic-bioremediation (EK-BIO) on remediating soil polluted by persistent organic pollutants (POPs) and heavy metals (mainly Cu, Pb and Ni), originated from electronic waste recycling activity. The results demonstrate that most of POPs and metals were removed from the soil. More than 60% of metals and 90% of POPs in the soil were removed after a 30-day EK-BIO remediation assisted by citrate. A citrate sodium concentration of 0.02 g/L was deemed to be suitable because higher citrate did not significantly improve treatment performance whereas increasing dosage consumption. Citrate increased soil electrical current and electroosmotic flow. After remediation, metal residues mainly existed in stable and low-toxic states, which could effectively lower the potential hazard of toxic metals to the surrounding environment and organisms. EK-BIO treatment influenced soil microbial counts, dehydrogenase activity and community structure.
This paper presents a review of soil contamination resulting from e-waste recycling activities, with a special focus on China, where many data have been collected for a decade. Soils in the e-waste areas are often contaminated by heavy metals and organic compounds, mainly polycyclic aromatic hydrocarbons (PAHs), polybrominated diphenyl ethers (PBDEs), polychlorinated and polybrominated biphenyls (PCBs and PBBs), dechlorane plus (DP), hexabromocyclododecanes (HBCDs), polychlorinated and polybrominated dibenzo-p-dioxins (PCDDs and PBDDs), and polychlorinated and polybrominated dibenzofurans (PCDFs and PBDFs), while other compounds, not systematically monitored, can be found as well. Pollutants are generally present in mixtures, so pollution situations are complex and diversified with a gradient of contamination from agricultural soils to hot spots at e-waste sites and mainly in open burning areas. It has been proved that pollutants were transferred to the food chain via rice in China, and that the population was threatened since high levels of various pollutants were detected in blood, placentas, hair, etc., of residents of e-waste sites. Eventually, soil remediation techniques are reviewed. Although there are many available techniques devoted to heavy metals and persistent organic pollutants, the current techniques for the e-waste sites, where these contaminants coexist, are very sparse. Phytoremediation has been investigated and co-cropping appears as a promising approach for the slightly contaminated agricultural soils. In some cases, different remediation techniques should be combined or trained, while the influence of coexisting contaminants and the removal sequence of contaminants should be considered. In hot spots, physical and chemical techniques should be used to reduce high pollution levels to prevent further pollutant dissemination. This review highlights the urgent needs for 1) characterization of pollution status in all the countries where e-wastes are recycled, 2) research on fate and toxicity of pollutant mixtures, and 3) development of combined techniques and strategies to remediate agricultural fields and hot spots of pollution.
In most developing countries, rapid economic growth and industrialization have transformed its landscape with significant effects on the environment. One major effect of this urbanization is the increase in waste generated and is more evident in developing nations since the capacity of these cities to collect, process or reuse and dispose solid waste is limited and is not sustainable. Disposing waste on land has been the most common and cheapest way of disposing it. But due to the uncontrolled dumping, the land has reached its carrying capacity which eventually affects the environment and its visual quality. Moreover, the quality of the wastes which has the potential for reuse in productive purposes is not considered.
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![Philippe Sentenac]()
- S. Ayeni
- Rod Lynch
Centrifuge tests were carried out to confirm and determine the effect of different pure alcohols, methyl t-butyl ether (MTBE) and mixtures of alcohols with gasoline and diesel on a thin disc of consolidated clay. The evolution of changes in the clay hydraulic conductivity with time was investigated and other structural changes due to chemical attack were monitored. The findings presented here demonstrate that the hydraulic conductivity of the clay appear to be generally related to the polarity of the chemicals and the dielectric constant. The cracking effect of butanol and MTBE on consolidated clay at low flow rate and low stress level was observed. The addition of ethanol or MTBE to diesel increased the clay permeability and the migration of organic chemical. The addition of ethanol to gasoline also caused an increase in the clay hydraulic conductivity. The effect of the association of alcohols with gasoline or diesel on the clay hydraulic conductivity is discussed, with a view to improving current pollution remediation techniques. KeywordsGasohols–Consolidated clay–Permeability–Gasoline remediation
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![Peter Shanahan]()
Groundwater is a critical resource for many of the world's cities. While a few cities (for example, New York) rely upon protected surface-water reservoirs for their supply, many more depend on groundwater. Conservation, protection, and management of groundwater are thus necessities for most cities. This chapter reviews the basics of groundwater hydrology, supply, and water quality, and then goes on to examine groundwater in the specific context of the urban environment.
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Source: https://www.researchgate.net/publication/284495489_Geoenvironmental_Engineering_Site_Remediation_Waste_Containment_and_Emerging_Waste_Management_Technologies_John_Wiley_Sons_Hoboken_N_J
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