Green Remediation or Sustainable Remediation: Moving From Dialogue to Common Practice

Different points of view have emerged concerning how to best consider and address the largely unexamined ancillary environmental impacts, and more particularly the social and economic impacts, of remediation activities. These views are generally categorized as “green remediation” and “sustainable remediation.” This article dissects the commonalities and differences between “green” and “sustainable” remediation approaches. Several key obstacles to the broader implementation of sustainable remediation practices are identified. Similarities identified among the two concepts offer a common ground and areas of collaboration. The objective of this article is to support maturation of the remediation industry by addressing the opposition to and supporting the implementation of sustainable remediation practices, including offering recommendations for a path forward. ©2015 Wiley Periodicals, Inc.     

Thermal desorption of PCB-contaminated waste at the waukegan harbor superfund site

In June 1992, SoilTech ATP Systems, Inc., completed the soil treatment phase of the Waukegan Harbor Superfund Project in Waukegan, Illinois, after approximately five months of operation. SoilTech successfully treated 12,700 tons of sediment contaminated with polychlorinated hiphenyls (PCBs) using a transportable SoilTech anaerobic thermal processor (ATP) system nominally rated at ten tons per hour throughput capacity. The SoilTech ATP technology anaerobically desorbs contaminants such as PCBs from solids and sludges at temperatures over 1,000° F. Principal products of the process are clean, treated solids and an oil condensate containing the hydrocarbon contaminants. At the Waukegan Harbor Superfund site, PCB concentrations in the sediments excavated and dredged from a ditch, lagoon, and harbor slip averaged 10,400 parts per million (ppm) (1.04 percent) and were as high as 23,000 ppm (2.3 percent). Treated soil was backfilled in an on-site containment cell. The removal efficiency of PCBs from the soil averaged 99.98 percent, relative to the project performance specification of 97 percent, and treated soil PCB concentrations were measured below 2 ppm. Approximately 30,000 gallons of PCB oil, desorbed from the feed material, were returned to the owner for subsequent off-site disposal. After modifications to the emissions control equipment, compliance with the 99.9999 percent destruction and removal efficiency (DRE) for PCBs in stack emissions required by the U.S. Environmental Protection Agency was achieved.     

Groundwater Remediation and Aquifer Clean-Up: A Case Study

Groundwater was being remediated with pump and treat technology at a facility where the groundwater was contaminated with commonly used degreaser solvents. Hydraulic conductivity of the heterogeneous residuum was beneficiated by applying pneumatic fracturing technology. The remedial system was controlled and monitored by a sophisticated remote telemetry system. A case history follows.     

Remediation process optimization: A status report

There are hundreds of contaminated sites with remediation systems that require evaluation and modification to accomplish cleanup goals. These systems are operating well past projected cleanup schedules, cost more than projected to operate, and may not be as protective of human health and the environment as planned. Remediation process optimization (RPO) is an effective method to assess the progress of a system toward achieving cleanup goals within desired time frames and to make the necessary changes in order to reach those goals. Eight main components to the RPO process are evaluated during a review and an implementation plan of recommended changes to the system is developed. Follow‐up and tracking are essential to successful RPO programs. In this article, the authors present a summary of a recent Technical and Regulatory (TechReg) Guidance Document (Interstate Technology and Regulatory Council [ITRC], 2004) and related Technology Overview Series on Advanced Topics in RPO (ITRC, 2006) in a distilled form. © 2007 Wiley Periodicals, Inc.     

Remediation of MTBE-Contaminated Water and Soil

As the number of leaking underground fuel tank sites with methyl tertiary butyl ehter (MTBE) contamination continues to grow, there is a need to develop cost-effective solutions for treatment of soil and water contamination. MTBE poses special challenges because of its physicochemical properties, in particular high solubility and low Henry's constant, low affinity for sorption, and very slow rate of microbial degradation. Advanced oxidation processes tend to generate undesirable by-products. Based on laboratory studies with hollow fiber membranes (HFM), a field-scale unit was constructed and tested at a number of sites, to determine the effectiveness of this technology in dealing with MTBE contamination. In addition, to treat the soil contamination, the HFM unit was coupled with a Spray Aeration Vapor Extraction (SAVE) unit, which is based on an internal combustion engine. The engine provides the means to treat soil vapors, as well as organic vapors from the spray aeration and HFM units. The overall treatment objectives of 5μg/l for MTBE and 1 μg/l for benzene were achieved with a treatment train consisting of an ion exchange unit, a spray aeration system, a hollow fiber membrane module and two granular activated carbon (GAC) units, for flowrates ranging from 3.8 to 30 l/min (1 to 8 gal/min). The ion exchange unit sewed to reduce water hardness and avoid scaling in the subsequent treatment units, extending the run-time of the entire system. Overall removal efficiencies for the spray aeration system and hollow fiber membrane module ranged from 85 to over 99 percent. High removal efficiencies (> 97%) were obtained at elevated water temperatures (54°C) or lower flowrates (up to 11 l/min). The GAC units were used only to polish the effluent and meet the discharge requirements. Soil, water, and gas phases are treated with this system. Cost estimates are provided for similar treatment processes, for water flowrates up to 38 l/min (10 gal/min). © 1999 John Wiley & Sons, Inc.     

Remediation Technologies Screening Matrix and Reference Guide: Version III

The U. S. Army Environmental Center (USAEC) is leading an effort to update the Remediation Technologies Screening Matrix and Reference Guide, Third Edition under the auspices of the Federal Remediation Technologies Roundtable (FRTR). Its purpose is to create a comprehensive “Remediation Technologies Yellow Pages” for use by those responsible for environmental cleanup. The Guide is being produced as a multiagency cooperative effort published under the FRTR. Members of this effort include USAEC, the U. S. Army Corps of Engineers (USACE), the Naval Facilities Engineering Service Center (NFESC), the Air Force Center for Environmental Excellence (AFCEE), the Environmental Protection Agency (EPA), the Department of Energy (DOE), the Department of the Interior (DOI), and the Interstate Technologies Regulation Cooperative (ITRC). This article provides a comprehensive look at environmental technology information provided in the electronic user-defined Remediation Technologies Screening Matrix and Reference Guide.     

Soil washing: Practical considerations and pitfalls

The use of soil washing to remove petroleum hydrocarbon contamination from the soil matrix is becoming more widely used. When viewed as a volume reduction tool, this technology shows some promise. However, ongoing research and treatability studies indicate that without further treatment, even larger-sized soil fractions (sands and cobbles) may retain hydrocarbon contamination at levels that require further cleaning prior to permanent disposal or reuse. The perception has been that by removing the sand from the soil matrix, thus achieving a 30 percent to 60 percent volume reduction, expensive post-washing treatment or approved disposal of the finer materials (silts and clays) would be cost-effective. There exists evidence to the contrary, however. Hydrocarbon retention after soil washing may be influenced by a number of factors unrelated to particle size. Soil characteristics that may play a role include soil humic acids, metal oxide coatings, geologic origin of the soil particles, and clay type. In this article the authors describe a laboratory study designed to evaluate the “cleanability” of two soils.     

Remediation and review: Developing groundwater strategy at the hanford site

The U.S. Department of Energy's (US DOE's) environmental challenges include remediation of the Hanford Site in Washington State. The site's legacy from nuclear weapons “production” activities includes approximately 80 square miles of contaminated groundwater, containing radioactive and other hazardous substances at levels above drinking water standards. In 1998, the U.S. General Accounting Office (US GAO), the auditing arm of Congress, concluded that groundwater remediation at Hanford should be integrated with a comprehensive understanding of the “vadose zone,” the soil region between the ground surface and groundwater. The US DOE's Richland Operations Office adjusted its program in response, and groundwater/vadose‐zone efforts at Hanford have continued to develop since that time. Hanford provides an example of how a federal remediation program can be influenced by reviews from the US GAO and other organizations, including the US DOE itself. © 2008 Wiley Periodicals, Inc.     

Remediation and stewardship: Coexisting processes to protect health and the environment

Organizations that manage property that poses risks for surrounding communities need to practice stewardship. Stewardship is defined as carrying out the responsibility to manage land and facilities in a sustainable manner, while being accountable to others who have a stake in those resources. This article reviews six case studies of organizational stewardship and derives a set of five lessons learned, along with four challenges. Lessons include developing stewardship goals, good stakeholder relationships, multiple approaches to safety, and encouraging innovation and stable funding. Challenges include bureaucratic processes, burdensome regulations, organizational continuity, and inter‐organizational cooperation. These crosscutting lessons learned about how to achieve success or avoid failure in long‐term management of resources can be applied to all types of public and private agencies, including the long‐term management of environmental contamination. © 2003 Wiley Periodicals, Inc.     

Risk Assessment in Remediation: Accurately Accounting for Uncertainty

Cleanup levels at hazardous waste sites are typically developed based at least in pan on either generic or site-specific risk assessments. Risk assessment in its purest form should be a measure of the potential for a site to cause adverse effects and therefore should be used as the basis for cleanup. However, the process of risk assessment continues to be subject to problems, primarily related to inherent uncertainties in the exposure parameters and toxicity criteria that are the building blocks of the risk assessment. Criticism of risk assessments and risk-based decisions range from comments that the process inadequately protects human health to comments that the process is overly protective, and examples of both ends of the spectrum are readily available. Site remediation professionals should be aware of the issues related to uncertainty and understand the potential problems in order to ensure appropriate and effective site cleanup. © 1999 John Wiley & Sons, Inc.     

Centrifugal Bioreactors and Their Application in Remediation

A new approach to the maintenance of large microbial populations for bioremediation purposes has been developed in which a centrifugal bioreactor is used to immobilize microbial populations at extremely high density. The cells are ordered into a three‐dimensional array through which wastewater or groundwater volumes may be flowed, unimpeded by frits or screens. The process methodology is independent of the type, shape, or viability of the individual cells immobilized and, thus, may be adapted to many different bioremediation needs. The utilization of this new process has been explored for three different types of remediation: the removal of heavy metals from wastewater, the aerobic degradation of methyl‐tert‐butyl ether (MTBE), and the anaerobic reduction of nitrate to nitrogen gas. This article discusses the use of centrifugal bioreactors and their application in remediation. © 2001 John Wiley & Sons, Inc.     

Remediation of sites contaminated with TCE

Widespread use of trichloroethylene (TCE) in the U.S. has resulted in its frequent detection in soil and groundwater. TCE can become a health hazard after being processed in the human liver; or reductive dehalogenation in the environment may result in production of vinyl chloride, a known carcinogen. This has generated a high degree of interest in efficient and cost-effective technologies that can be used to remediate soil and ground-water contaminated with TCE. The purpose of this paper is to present and discuss relevant physicochemical properties and reactive mechanisms of TCE, and to delineate and discuss promising remediation methodologies that have been proposed and/or demonstrated for restoring contaminated subsurface environments. The information in this article has been funded wholly or in part by the U.S. EPA under contract No. 68–C8–0058 to Dynamac Corporation; it has been subjected to the Agency's peer and administrative review process and approved for publication.     

Remediation of metal-contaminated sites using plants

Heavy metal contamination of soil resulting from anthropogenic sources poses a significant challenge in many industrialized societies. The current technologies employed for removal of heavy metals often involve expensive ex-situ processes requiring sophisticated equipment and removal, transportation, and purification of the soil. Generally, in-situ remedial technologies are favored to ex-situ methods for detoxification, neutralization, degradation, or immobilization of contaminants. In-situ bioremediation is increasingly favored because of its effectiveness and low cost. A new type of bioremediation, known as vegetative remediation or “phytoremediation,” uses metal-tolerant hyperaccumulator plants to take up metal ions from soils and store them in their aboveground parts. To select the appropriate phytoremediation technology, one must understand the technical feasibility, cost effectiveness, and availability of the suitable plant species. Equally important is determining whether the site's soil conditions are optimal to enhance or restore the soil biological activity. Before phytoremediation can be exploited on a contaminated site, greenhouse-scale confirmatory testing is necessary to measure plant uptake and correlate shoot metal concentrations to available soil metals. These tests also validate that the harvesting and subsequent disposal of metal-containing plant tissues are environmentally safe and manageable.     

Integrating Groundwater Conservation and Reuse into Remediation Projects

Groundwater remediation projects generally involve extraction and treatment of contaminated groundwater. The current state of the practice does not include an emphasis on conservation and reuse of groundwater. Consequently treated groundwater is typically disposed in sanitary or storm sewers. Longstanding water conservation and reuse practices in the municipal wastewater industry provide a body of experience available to the remediation industry. Case studies of conservation and reuse options for groundwater at remediation sites have been found across a broad range of geographic settings and regulatory jurisdictions. The intent of this article is to stimulate a more holistic view of the groundwater associated with remediation projects and to promote conservation and beneficial reuse of a vital natural resource. © 2014 US Sustainable Remediation Forum     

Environmental impact and mechanical behavior study of experimental road made with river sediments: recycling of river sediments in road construction

Dredging operations are necessary to maintain harbour activities, to prevent floods, and to restore ecosystem. These sediments after dredging are considered as waste, and their management is a complex problem. In the context of sustainable development, traditional solutions, such as dumping, will be more and more regulated. More than ever with the shortage of aggregates from quarries, dredged sediment could constitute a new granular material source for Civil Engineering domain. The principal objective of this works is to use dredged river sediments in the road construction. This study consists to determine the physical–chemical, geotechnical, and environmental impact characteristics of raw river sediments. To improve the mechanical performance of this river material be used in road construction, a treatment by the hydraulic binder in combination with granular corrector has been proposed. The impacts of the treated material on the environment have been evaluated. The last part of this study focuses on the realization of an experimental road with the designed mixes in the laboratory. The validation of mechanical characteristics and the study of the environmental impacts have been made on core samples from the experimental road. The monitoring of the quality of the percolating water and runoff water has been explored. The obtained results in laboratory and in situ are promising for potential use of river sediments in foundation layer of the road construction.     

Remediation with cyclodextrin: Recovery of the remedial agent by membrane filtration

Cyclodextrin‐enhanced flushing of contaminants from the subsurface is a promising innovative remediation technology. It will become more economically viable at more sites if methods can be developed to recover and reconcentrate the cyclodextrin solution after it has been flushed through an aquifer. The goal of this study was to determine if membrane technology is capable of meeting that need. Five membranes with different material properties were tested for this purpose in the laboratory. The results of these tests indicate that there are large differences both in the efficiency of these membranes to extract hydroxpropyl‐β‐cyclodextrin (HPCD) and their stability when exposed to trichloroethylene (TCE) at concentrations near aqueous solubility. Not only does the molecular weigh cutoff (MWCO) of a membrane determine if HPCD can be retained, but crucial selection criteria are the membrane's resistance and compatibility with TCE. Of the five membrane materials tested, only two (polymer composite membrane and polysulfone) met both these requirements. The polymer composite membrane (MPF‐44) showed reliable and stable HPCD recoveries (>95 percent) even when exposed to high TCE concentrations. The polysulfone membrane showed high HPCD recoveries, 88.5 ± 0.4 percent to 97 percent ±1 percent for ultrafiltration and nanofiltration membranes, respectively. However, membrane swelling and deterioration became a problem at high TCE concentrations (>1,000 mg/L). These problems diminished when the TCE concentration was less than 1 mg/L. Field tests demonstrated that batch mode treatment by ultrafiltration doubled the cyclodextrin concentration from 5 to 10 percent within three hours at a constant operating pressure of 13 psi. Under continuous single‐pass treatment conditions, cyclodextrin concentration also increased, although the rate of increase was much smaller than in batch mode. Overall, these tests showed that cyclodextrin recovery is possible under field conditions. © 2007 Wiley Periodicals, Inc.     

Remediation of fly ash landfills through plantation

In India, a significant area of land is occupied by preexisting coal‐fired thermal power plants (TPPs) for the storage of fly ash slurry in ash ponds. However, the area available for storage of fly ash at these TPPs is limited. In addition, this type of fly ash disposal poses a problem due to restricted land availability and potential contamination issues. A viable alternative is the reclamation of fly ash ponds by plantation. A study at the Ramagundam Super Thermal Power Station (RSTPS) in Andhra Pradesh, India, on reclamation of a portion of an ash‐filled, low‐lying area has been performed. This article describes the characteristics of the RSTPS pond ash, ash leachates, and improvements in the fertility status of the reclaimed area over a three‐year period. Furthermore, morphometric observations of different planted species indicate that these types of ash‐filled, low‐lying areas can be suitably reclaimed and the nutrient‐rich leachate from ash‐filled areas potentially can be used for irrigation purposes. © 2008 Wiley Periodicals, Inc.