Environmental Remediation Technologies Research Articles

Remediation of Heavy Metal-Contaminated Farm Soil Using Turnover and Attenuation Method Guided with a Sustainable Management Framework

Remediation for contaminated farm soil had become an important task in Taiwan for the authorities because many farms had been contaminated with heavy metals due to illegal discharges of industrial wastewater. A comprehensive and effective remediation methodology for heavy metal-contaminated farm soil was presented in Taiwan, which integrated assessment of soil contamination and environmental characteristics, remediation technology, and performance assessment. Turnover and attenuation method was chosen and applied in this study based on assessment criteria of social, technological, economical, and environmental feasibilities. However, there were some difficulties needed to be solved when turnover and attenuation method was applied because of great variation of environmental characteristics in Taiwan. A sustainable management framework based on Managing for Results method was therefore developed for guiding the accomplishment of the remediation tasks. Three contaminated sites had been successfully completed for the remediation tasks in this study by using the proposed integral methodology. The distribution of heavy metal concentrations in soils and environmental characteristics had been predicted using the proposed rule for determining adequate number and locations of sampling points and used to calculate the excavation depth for each area. The results of performance measurements showed that the farm lands had recovered their agricultural utility to meet the landowners' request, heavy metal concentrations in the soils had been reduced with proper attenuation ratio, remediation cost had been controlled in the range of the budget, and heavy metal concentrations in the soils and crops after remediation can meet the regulatory limits. The comprehensive and effective remediation methodology could be employed to assure the effectiveness and efficiency of the remediation tasks based on the principles of sustainable development, as observed from the analytical results of the three contaminated cases.

Removal and degradation of aromatic compounds from a highly polluted site by coupling soil washing with photocatalysis

The possible application of two environmental remediation technologies – soil washing and photocatalysis – to remove and decompose various aromatic pollutants present in excavated soils of a contaminated industrial site has been investigated. Aqueous solutions containing the non-ionic surfactant Brij 35 were used to extract the contaminants from the soil samples. The photocatalytic treatment of the obtained washing wastes, performed in the presence of TiO 2 suspensions irradiated with simulated sunlight, showed a slow abatement of the toxic compounds due to the relevant concentrations of organics in the waste. A neat improvement of the process performances, obtained by operating in the presence of added potassium peroxydisulfate, suggests a feasible treatment route.

Irradiation of sorbents by ions of polymorphic metals for modeling 90strontium sedimentation

Advances in radioecology can support improvements in environmental remediation technologies, especially by illuminating interaction processes between polymorphic metal radionuclides and various materials and their ions in aqueous solutions. This study modeled interaction processes of 90Sr with transitive metals to delineate the behavior of polymorphic metal radionuclides. Experimental and modeling results confirmed Sr sedimentation was sensitive to the physical impact of radionuclides on various sorbents and possible chemical reactions occurring between the radionuclides and sorbents. Models were developed to simulate 90Sr sedimentation process, and the potential physical and chemical reactions accompanying the process. Models were verified, inorganic salts were used as sorbents to absorb metal cations, activity levels were recorded before and after mixing the inorganic salts while the efficiency of sedimentation using the heavy metals composites was quantified. This research demonstrates that the process of the sedimentation is complex and occurs in several stages. Micro-structural analysis shows that zones of interaction between the sorbent and source metal are formed during the irradiation of the target's metal surface. Electrical-microscopic analysis indicates that the composition of the formed zones of interaction of Ti (Sr) with target metals has various structures. Roentgenophase analysis indicates that the interaction of the ions of a precipitable source and a target occurs according to constitution diagrams of equilibrium systems. The results indicate that application of inorganic salts composites based on modeling increases the efficiency of the deactivation of aqueous solutions when compared to standard aluminum sulfate composite. Experimental and modeling results confirm 90Sr sedimentation is sensitive to the physical impact of radionuclides on various sorbents and possible chemical reactions occurring between the radionuclides and sorbents. The models support estimation of the physical impact of polymorphic metal radionuclides on various components of sorbents and possible chemical reactions occurring between the radionuclides and sorbents during the interaction. Inorganic salt composites deactivate and clear 90Sr and Sr+2 from water.

Pilot‐scale evaluation using bioaugmentation to enhance PCE dissolution at dover AFB national test site

AbstractAn Interstate Technology and Regulatory Council (ITRC) forum was recently held that focused on six case studies in which bioremediation of dense nonaqueous‐phase liquids (DNAPLs) was performed; the objective was to demonstrate that there is credible evidence for bioremediation as a viable environmental remediation technology. The first two case studies from the forum have been previously published; this third case study involves a pilot‐scale demonstration that investigated the effects of biological activity on enhancing dissolution of an emplaced tetrachloroethene (PCE) DNAPL source. It used a controlled‐release test cell with PCE as the primary DNAPL in a porous media groundwater system. Both laboratory tests and a field‐scale pilot test demonstrated that bioaugmentation can stimulate complete dechlorination to a nontoxic end product and that the mass flux from a source zone increases when biological dehalorespiration activity is enhanced through nutrient (electron donor) addition and bioaugmentation. All project goals were met. Important achievements include demonstrating the ability to degrade a PCE DNAPL source to ethene and obtaining significant information on the impacts to the microbial populations and corresponding isotope enrichments during biodegradation of a source area. © 2007 Wiley Periodicals, Inc.

Magnetic particle technology in environmental remediation and wildlife rehabilitation

The use of magnetic particles in environmental remediation and wildlife rehabilitation is currently under investigation at Victoria University, in collaboration with the Phillip Island Research Centre, Victoria, Australia. Iron powder has been shown to be very effective for the magnetic cleansing of feathers and plumage and is almost ideal for this purpose, being non-toxic, a non-irritant and recyclable. Detailed investigations have demonstrated that by varying particle size, particle structure and surface texture, the efficacy of oil removal from feathers and plumage can be successfully manipulated. In this regard, it is possible to identify a grade of iron powder whereby, within experimental error, effectively 100% removal of a variety of fresh contaminants from different matrices, including feathers, can be achieved. Our investigations have been extended to the application of such particles to the successful removal of tarry and weathered/tarry contamination. The results of these investigations have indicated that, for such contaminants, removals ranging from 97–99% may be achieved. Magnetic particle technology may also be adapted for the screening of pre-conditioning agents that can further assist in the removal of tarry and weathered/tarry contamination from feathers. These investigations suggest that magnetic particles could have an important role to play in environmental remediation and wildlife rehabilitation as a clean and effective technology.

Enhanced reductive dechlorination of PCE in unconsolidated soils

AbstractAn Interstate Technology and Regulatory Council (ITRC) forum was recently held that focused on six case studies in which bioremediation of dense nonaqueous phase liquids (DNAPLs) was performed. The objective was to demonstrate that there is credible evidence for bioremediation as a viable environmental remediation technology. A discussion of the first case study from the ITRC forum was published in the previous issue of Remediation. This article presents a discussion of the second case study, which involves enhanced reductive dechlorination (ERD) of tetrachloroethene (PCE) in unconsolidated soils—primarily silts and clays with very low permeabilities. The project results indicate that complete reductive dechlorination was achieved and provide encouragement that large amounts of nonaqueous solvent can be brought into the reductive dechlorination treatment process by dissolution and desorption, giving support to the contention that the capacity to attack nonaqueous mass is a prerequisite for any effective treatment of DNAPL source zones. The site geology for this project was relatively unfavorable, and further work is needed to confirm that the ERD technology can economically reach a natural attenuation endpoint for this type of setting. © 2006 Wiley Periodicals, Inc.

Fitoremediasi dan Potensi Tumbuhan Hiperakumulator

Phytoremediation is defined as cleaning up of pollutants mediated primarily by plants. It is an emerging technology for environmental remediation that offers a low-cost technique suitable for use against different types of contaminants in a variety of media. Phytoremediation is potentially applicable to a diversity of substances, involving hyperaccumulators heavy metals and radionuclides. It is also applicable to other inorganic contaminants such as arsenic, various salts and nutrients, and a variety of organic contaminants, including explosives, petroleum hydrocarbons and pesticides. At least there are one taxon of plant as hyperaccumulator for Cd, 28 taxa for Co, 37 taxa for Cu, 9 taxa for Mg, 317 taxa for Ni, and 11 taxa for Zn. Extensive progress were done in characterizing physiology of plants which hyperaccumulate or hypertolerate metals. Hypertolerance is fundamental to hyperaccumulator, and high rates of uptake and translocation are observed in hyperaccumulator plants. Hyperaccumulator plants and agronomic technology were undertaken to improve the annual rate of phytoextraction and to allow recycling of soil toxic metals accumulated in plant biomass. These techniques are very likely to support commercial environmental remediation. Most phytoremediation systems are still in development, or in the stage of plant breeding to improve the cultivars for field use. However, application for commercial purposes has already been initiated. Many opportunities have also been identified for research and development to improve the efficiency of phytoremediation.

Phytoremediation and Potency of Hyperaccumulator Plants

Phytoremediation is defined as cleaning up of pollutants mediated primarily by plants. It is an emerging technology for environmental remediation that offers a low-cost technique suitable for use against different types of contaminants in a variety of media. Phytoremediation is potentially applicable to a diversity of substances, involving hyperaccumulators heavy metals and radionuclides. It is also applicable to other inorganic contaminants such as arsenic, various salts and nutrients, and a variety of organic contaminants, including explosives, petroleum hydrocarbons and pesticides. At least there are one taxon of plant as hyperaccumulator for Cd, 28 taxa for Co, 37 taxa for Cu, 9 taxa for Mg, 317 taxa for Ni, and 11 taxa for Zn. Extensive progress were done in characterizing physiology of plants which hyperaccumulate or hypertolerate metals. Hypertolerance is fundamental to hyperaccumulator, and high rates of uptake and translocation are observed in hyperaccumulator plants. Hyperaccumulator plants and agronomic technology were undertaken to improve the annual rate of phytoextraction and to allow recycling of soil toxic metals accumulated in plant biomass. These techniques are very likely to support commercial environmental remediation. Most phytoremediation systems are still in development, or in the stage of plant breeding to improve the cultivars for field use. However, application for commercial purposes has already been initiated. Many opportunities have also been identified for research and development to improve the efficiency of phytoremediation.

Application of the open path FTIR with COL1SB to measurements of ozone and VOCs in the urban area

Abstracts The CO nstrained L1 -norm minimization with the S ynthetic B ackground generation method (COL1SB) is newly developed open-path FTIR analysis software, designed to efficiently handle chemical interferences and to systematically generate background spectra. The performance of COL1SB was evaluated mainly against artificially generated field spectra. The present paper aims at application of COL1SB to ambient monitoring. In order to satisfy low detection limit requirements of ambient monitoring, COL1SB was further improved to accurately determine path averaged water vapor pressures, to dynamically select appropriate spectral bands, and to use site specific background spectra. The modified COL1SB was applied to measure ozone, ammonia, methane, carbon monoxide, and 26 VOC species in the park located at the urban area from 12:00 a.m., 25 May to 12:00 a.m., 26 May 2000. The open-path FTIR measurements for ozone, water vapor, alkane concentrations compared very well with those by sampling methods both in magnitudes and in diurnal variations. Furthermore, the detection rates of VOCs were considerably enhanced such that the detection rates based on the correlation coefficients appeared to be above 50% for 12 species out of 16 representative chemical species. Especially ethylene and isoprene, chemically reactive olefins, had high detection rates exceeding 80% despite of their low concentrations. These detection rates by COL1SB are 2–5 times higher than those derived by the conventional CLS method in the previous work (SPIE Conference on Environmental Monitoring and Remediation Technologies SPIE (1998) 3534, 140).

Analytical and Environmental Chemistry in the Framework of Risk Assessment and Management: The Lagoon of Venice as a Case Study

Prevention of toxic pollutant discharge and remediation of contaminated sediments and soils are topics increasingly addressed by the scientific community and the stakeholders. The research activity carried out on the lagoon of Venice highlights the crucial role played by analytical and environmental chemistry in assessing the environmental behavior of chemicals (i.e. occurrence level, transformation, ultimate fate) and exposure of human and environmental targets to pollutants. The extrapolation from analytical data to decisional steps was accomplished by data treatment (descriptive and multivariate statistics, spatial statistics), environmental modeling (e.g. partitioning bioaccumulation models and linear regression models), environmental risk assessment (ERA), and a GIS-based Decision Support System (DSS). Results obtained by this integrated approach supported analytical and environmental chemistry by improving the selection of priority pollutants, optimizing sampling design, and identifying critical environmental pathways. Both uncertainty minimization and cost saving of the overall decision process could be achieved. Selected results are presented here on the application of the proposed approach to the contaminated sediments of the lagoon of Venice and to the brownfield of the Porto Marghera industrial district. Both well-known persistent pollutants (e.g. polychlorinated dioxins/furans (PCDD/Fs), polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), metals and metalloids, and aromatic surfactants and their metabolites), as well as new classes of pollutants (e.g. endocrine disrupting compounds, EDCs) were investigated. The analytical data indicated that the most persistent and toxic organic and inorganic chemicals were found mainly in bottom sediments (especially those near the Porto Marghera industrial district), while substances such as surfactants and their metabolites and EDCs occurred mainly in water and were redistributed over the whole lagoon. Exposure characterization allowed Environmental Risk Assessment (ERA) to be undertaken, including the estimation of risk for both human and environmental health. The ERA procedure, developed according to a tiered approach, was applied to contaminated soils of the Porto Marghera industrial district. The ecological risk associated with contaminated lagoon sediments for the benthic community and aquatic food web was also assessed, resulting in a significant risk posed especially by mercury, cadmium and PAHs. Finally, a risk-based decision support system (DSS) for the rehabilitation of the Porto Marghera contaminated site was developed, which included environmental risk and remediation technologies.

Nanoscale Iron Particles for Environmental Remediation: An Overview

Nanoscale iron particles represent a new generation of environmental remediation technologies that could provide cost-effective solutions to some of the most challenging environmental cleanup problems. Nanoscale iron particles have large surface areas and high surface reactivity. Equally important, they provide enormous flexibility for in situ applications. Research has shown that nanoscale iron particles are very effective for the transformation and detoxification of a wide variety of common environmental contaminants, such as chlorinated organic solvents, organochlorine pesticides, and PCBs. Modified iron nanoparticles, such as catalyzed and supported nanoparticles have been synthesized to further enhance the speed and efficiency of remediation. In this paper, recent developments in both laboratory and pilot studies are assessed, including: (1) synthesis of nanoscale iron particles (10–100nm, >99.5% Fe) from common precursors such as Fe(II) and Fe(III); (2) reactivity of the nanoparticles towards contaminants in soil and water over extended periods of time (e.g., weeks); (3) field tests validating the injection of nanoparticles into aquifer, and (4) in situ reactions of the nanoparticles in the subsurface.

Phytoremediation, Part I: Fundamental Basis for the Use of Plants in Remediation of Organic and Metal Contamination

Phytoremediation, the use of plant systems for contaminant cleanup, is among the fastest growing areas of environmental remediation research, technology development, and implementation. The practice is facilitated by a number of plant adaptations. First, selected plant species can take up and accumulate certain metals in their shoots at levels that are toxic to ordinary plants (hyperaccumulation). The phenomenon is an evolutionary adaptation of specific plant species to natural metal enrichments; consequently, its occurrence is geographically restricted, and the plant species involved are highly specific with respect to types of metals tolerated. Other plant species can take up, metabolize and thereby detoxify certain organic contaminants in their shoots, or cause their transformations through substances released into their root zones (rhizospheres). The extent to which an organic contaminant may be translocated in plants is determined largely by its partitioning into lipid phases (its lipophilicity), while rhizo-sphere transformations are determined largely by types and amounts of plant exudations, and microbial populations that are stimulated by these exudates. Interactions between plant systems and contaminants that can facilitate phytoremediation are complex, and complicated further by strong influences of climate, particularly temperature, and matrix factors such as nature and reactivity of surfaces, pH, and oxidation-reduction statuses. The ways in which the various factors interact to render a contaminant more or less susceptible to phytoremediation are discussed, with the objective of providing information needed for decision making when considering phytoremediation for the cleanup of particular contaminants.

ION-SELECTIVE POLYMER-SUPPORTED REAGENTS

ABSTRACT The design and synthesis of polymer-supported reagents that can selectively complex targeted metal ions from multi-component solutions will continue to be an important area of research into the 21st century. Environmental remediation and sensor technology are only two of a number of areas in which such polymers can be applied. This paper reviews the recent literature with an emphasis on the key ligands that have been immobilized in order to better understand where this research is heading in the near future.

An introduction to geocatalysis

Heterogeneous catalysis at mineral surfaces, or geocatalysis, may be important in natural systems. This contribution reviews how catalyst may influence reactions and several examples, mostly taken from the geochemical literature, are presented to illustrate the most important concepts. Two key characteristics that define a catalyst are activity and selectivity. Activity is the extent to which the catalyst can facilitate the rate of conversion of reactant to product. The selectivity of the catalyst refers to the ability of a catalyst to facilitate a specific reaction pathway where a reaction may proceed via multiple pathways. Photocatalysis is presented as a separate class of catalysis because reactions are only catalyzed when the system is illuminated with light of suitable wavelength. Three mechanisms of photocatalysis (photolysis, photoelectrochemical reaction, and charge injection) are discussed. Geocatalysis is particularly important for reactions with high activation energies, such as isotopic exchange reactions involving SO 4–H 2S, H 2O–SO 4, H 2O–PO 4, CO 2–CH 4 and transformations of humic acids and kerogen. While photocatalysis is limited to surficial aquatic environments, it may be of great importance in regulating the concentrations of redox-sensitive elements in the photic zones of lakes, streams, hot spring, and oceans. Photoelectrochemical reactions, such as the reduction of dinitrogen and carbon dioxide are thought to have been important in the origin of life on Earth. Geocatalysis may also prove to be useful in designing new environmental remediation technologies. For example, it is shown that sphalerite and ilmenite are capable of degrading chlorinated carbon compounds via a photocatalytic mechanism.

Technology transfer of an innovative remediation technology from the laboratory to the field: a case study of in situ aerobic cometabolic bioremediation

Scaling-up an environmental remediation technology from the laboratory to the field to commercial use may be problematic at various levels. There could be a number of scientific and engineering problems that must be overcome when transitioning a technology from the laboratory to the field. Mass transfer limitations, large-scale spatial heterogeneities, and fluctuating environmental conditions, all of which may not play a role in the laboratory, must be addressed in the field. Added to these considerations are regulatory and legal issues. Questions regarding liability and permitting must be satisfactorily dealt with in order to demonstrate and evaluate a new remediation technology in the field. Finally, to commercialize an innovative technology that has been successfully demonstrated, cost and performance data must be presented in a manner that convinces stake-holders (site owners, regulators, consultants/contractors, and the public) that the technology can accomplish remediation more economically, safely, and efficiently than conventional technologies.

Managing Asia's environmental crisis: EQM opportunities for remediation and technology transfer

AbstractConditions of environmental pollution and degradation in Asia are among the worst in the world. Rapid economic growth and industrialization over the past half century have accelerated the pollution of air, water, and land resources in a region with the world's largest concentration of population. As the economics of Asia recover from financial crisis in the late 1990s, they will face a more serious environmental crisis in the early years of the 21st century. Remediation of soil and water contamination will become a stronger concern in the region, as the human health impacts become more visible and widespread. Although environmental remediation is only beginning to emerge in Asia as a solution to problems of natural resource degradation, the authors show how U.S. firms with experience in quality environmental management and biological remediation technologies will find new opportunities for exports and technology transfer. Environmental technology and services firms interested in Asia must understand both the opportunities for and barriers to operating in Asia.

Synthesizing Nanoscale Iron Particles for Rapid and Complete Dechlorination of TCE and PCBs

Transformation of halogenated organic compounds (HOCs) by zero-valent iron represents one of the latest innovative technologies for environmental remediation. For example, iron can be used to construct a reactive wall in the path of a contaminated groundwater plume to degrade HOCs. In this paper, an efficient method of synthesizing nanoscale (1−100 nm) iron and palladized iron particles is presented. Nanoscale particles are characterized by high surface area to volume ratios and high reactivities. BET specific surface area of the synthesized metal particles is 33.5 m2/g. In comparison, a commercially available Fe powder (<10 μm) has a specific surface area of just 0.9 m2/g. Batch studies demonstrated that these nanoscale particles can quickly and completely dechlorinate several chlorinated aliphatic compounds and a mixture of PCBs at relatively low metal to solution ratio (2−5 g/100 mL). Surface-area-normalized rate constants (KSA) are calculated to be 10−100 times higher than those of commercially availa...

Environmental remediation technology implementation decision patterns

Each year, environmental technology implementation involves many millions of dollars in the United States alone. The economics of making decisions to continue research, to make changes to processes, or to introduce new products is a critical element in the success of organizations. In previous work by Paladino and Longsworth (1996), the importance of economic factors has been postulated to increase according to a set pattern throughout the implementation process. The authors seek to validate this theory and develop a better understanding of decision patterns related to technology implementations in the environmental remediation business area.

Evaluating the cost‐effectiveness of new environmental technologies

AbstractThe purpose of this article is to present a framework for evaluating the cost‐effectiveness of innovative technologies for environmental characterization, remediation, monitoring, and waste management. The authors describe the steps involved in actually using the methodology to perform a cost‐effectiveness analysis. They provide basic techniques for designing a fair comparison, developing scenarios, choosing a baseline technology, assessing relative performance, evaluating life‐cycle costs, and calculating cost savings. Examples are used to illustrate these concepts and a case study is presented involving a new remediation technology called in‐situ air stripping.

Constraints on mass balance of soil moisture during in situ vitrification

In situ vitrification (ISV) is an environmental remediation technology used to melt contaminated soil sites into more stable configurations. The behavior of water and other volatile constituents in the soil-melt system is important to the overall performance of the ISV technology. Mass and volume balance constraints are used to derive a method to indirectly estimate the volume of: (1) soil that dehydrates and releases water vapor to the off-gas, and (2) outside air pulled into the off-gas treatment system. These constraints allow us to speculate on whether some water may remain in the soil rather than being completely transported into the off-gas system. The method is tested with data from a field-scale test. Results suggest that, contrary to previous conceptual models, not all water that is vaporized reaches the surface and captured by the off-gas treatment system. It is probable that some percentage remains within the soil beneath and around the molten ISV mass.