Quantitative Environmental Footprints and Sustainability Evaluation of Contaminated Land Remediation Alternatives for Two Case Studies

Since the US Environmental Protection Agency (US EPA) launched its “green remediation” program and EU member states began to reassess their national regulations for environmental remediation in order to reach a Europe‐wide consensus on policy and standards, the need and interest for sustainable remediation of contaminants from brownfields has grown considerably. Concomitantly, the ability to calculate and assess the suitability as well as the environmental footprints and associated risks of a growing number of remediation techniques has become a priority. The authors quantitatively evaluate the differences between various remediation techniques, and for this purpose, a number of ex situ and in situ remediation techniques are adapted to model 21 remediation scenarios for two contaminated sites in the Gothenburg region of Sweden: the Bohus Varv site on the Göta älv river bank and the Hexion site in Mölndal. A wide range of quantitative results for these models are presented, compared, and analyzed. Based on the results from both projects, it is concluded that: (1) remediation techniques requiring long distance residual transportation have significant footprints, except the transportation of contaminated residuals by train due to Swedish energy production conditions; (2) residual transportation by ship results in much higher SO_x, NO_x, and particle releases compared to the other alternatives; and (3) residual transporation by truck results in high accident risks. Finally, activities powered by electricity result in a reduced footprint compared to activities powered by fossil fuels, considering Swedish energy production conditions. The authors conducted a cross‐benefit analysis of SiteWise^TM applications which recognizes its potential as a tool for presenting life cycle assessment analyses with appropriate system boundary definitions and an easy inventory analysis process. Results from this tool provide valuable support to decision makers aiming at more sustainable remediation. © 2013 Wiley Periodicals, Inc.     

Effect of chelating agents in phytoremediation of heavy metals

Chelate‐assisted metal uptake by plants has only recently been discovered in the remediation industry. The simultaneous accumulation of lead, arsenic, copper, and cadmium in plants after application of chelating agents to soil is a promising technology enhancement for phytoremediation. One of the most powerful and commonly used chelating agents is ethylene diamine tetra acetic acid (EDTA), which forms complexes with many of the metal contaminants within the natural environment. This study was conducted to determine the efficiency of an emergent wetland plant species Typha sp. and floating wetland macrophytes such as Pistia sp., Azolla sp., Lemna sp., Salvinia sp., and Eichhornia sp. in phytoremediation of various heavy metals with addition of a chelating agent such as EDTA. EDTA addition to the treatment systems increased the uptake of heavy metals by plants, which was much pronounced with lead and copper. However, the pattern of uptake by plants was similar as that of heavy metals without EDTA amendments. © 2012 Wiley Periodicals, Inc.     

Recent Developments in Cleanup Technologies

Although the reaction mechanics are somewhat mysterious, the use of iron for in situ groundwater treatment has recently gained considerable attention and respect in the remediation industry. The basic scientific principles of both applications of iron have been known for over a century; however, both were nearly unheard of as remediation technologies five years ago. Both technologies have a strong potential for widespread use. They are commercially available, have been proven in field studies, are less expensive than traditional pump and treat technologies, and, in many types of groundwater systems, may be able to meet difficult-to-achieve groundwater treatment standards. As these technologies continue to undergo development, there could be considerably more aggressive applications used to treat ground-water containing high concentrations of chlorinated organics and DNAPLs.     

Sustainable soil remediation by refrigerated condensation at sites with “high‐concentration” recalcitrant compounds and NAPL: Two case studies

Remediation of recalcitrant compounds at sites with high concentrations of volatile organic compounds (VOCs) or nonaqueous‐phase liquids (NAPLs) can present significant technical and financial (long‐term) risk for stakeholders. Until recently, however, sustainability has not been included as a significant factor to be considered in the feasibility and risk evaluation for remediation technologies. The authors present a framework for which sustainability can be incorporated into the remediation selection criteria focusing specifically on off‐gas treatment selection for soil vapor extraction (SVE) remediation technology. SVE is generally considered an old and standard approach to in situ remediation of soils at a contaminated site. The focus on off‐gas treatment technology selection in this article allows for more in‐depth analysis of the feasibility evaluation process and how sustainable practices might influence the process. SVE is more commonly employed for recovery of VOCs from soils than other technologies and generally employs granular activated carbon (GAC), catalytic, or thermal oxidation, or an emerging alternative technology known as cryogenic‐compression and condensation combined with regenerative adsorption (C3–Technology). Of particular challenge to the off‐gas treatment selection process is the potential variety of chemical constituents and concentrations changing over time. Guidance is available regarding selection of off‐gas treatment technology (Air Force Center for Environmental Excellence, 1996; U.S. Environmental Protection Agency, 2006). However, there are common shortcomings of off‐gas treatment technology guidance and applications; practitioners have rarely considered sustainability and environmental impact of off‐gas treatment technology selection. This evaluation includes consideration of environmental sustainability in the selection of off‐gas treatment technologies and a region‐specific (Los Angeles, California) cost per pound and time of remediation comparisons between GAC, thermal oxidation, and C3–Technology. © 2008 Wiley Periodicals, Inc.     

Assessing the Phytoremediation Potential of Tall Fescue and Sericea Lespedeza for Organic Contaminants in Soil

The phytoremediation potential of using tall fescue (Festuca arundinacea Schreb.) grass and sericea lespedeza (Lespedeza cuneata [Dum. ‐Cours.]) legume species was assessed using three different groups of organic contaminants in soil. One hundred parts per million (ppm) each of a nitroaromatic compound (TNT), a polycyclic aromatic hydrocarbon (Pyrene), and a polychlorinated biphenyl (Aroclor 1248) were used to contaminate the soils. The experiments were conducted using soils with high and low organic‐matter content. The results indicate that recoveries of Pyrene and TNT were very low in all treatments in soil with high organic‐matter content (6.3 percent) compared with recoveries in soil with low organic‐matter content (2.6 percent). In contrast, recoveries of PCB from soil were not dependent on the soil's organic‐matter content. Planting both the legume and grass species had significant effect on the transformations of TNT and PCB in the soil with low organic‐matter content and did not affect the fate of Pyrene in both soils. The amount of TNT transformed in the four months of plant growth was 63 percent in the tall fescue and 46 percent in the sericea‐planted soils, compared with only a 15 percent unaccounted loss in the unplanted control soils. Furthermore, the grass species, with its massive root system, was significantly better at causing TNT dissipation compared with the legume species, which has less root vegetative mass. The plant biomass, particularly the shoot weight of the tall fescue grass, was significantly increased as a result of TNT treatment. Tall fescue and sericea biomass did not appear to have any significant effect on Pyrene transformation. Planting sericea provided a significantly high level of PCB transformation in soils with either high or low amounts of organic matter. Tall fescue did not appear to have any significant effect on PCB transformation. © 2002 Wiley Periodicals, Inc.     

1,4‐Dioxane Treatment Technologies

The chlorinated solvent stabilizer 1,4‐dioxane (DX) has become an unexpected and recalcitrant groundwater contaminant at many sites across the United States. Chemical characteristics of DX, such as miscibility and low sorption potential, enable it to migrate at least as far as the chlorinated solvent from which it often originates. This mobility and recalcitrance has challenged remediation professionals to redesign existing treatment systems and monitoring networks to accommodate widespread contamination. Furthermore, remediation technologies commonly applied to chlorinated solvent co‐contaminants, such as extraction and air stripping or in situ enhanced reductive dechlorination, are relatively ineffective on DX removal. These difficulties in treatment have required the industry to identify, develop, and demonstrate new and innovative technologies and approaches for both ex situ and in situ treatment of this emerging contaminant. Great strides have been made over the past decade in the development and testing of remediation technologies for removal or destruction of DX in groundwater. This article briefly summarizes the fate and transport characteristics of DX that make it difficult to treat, and presents technologies that have been demonstrated to be applicable to groundwater treatment at the field scale.  ©2016 Wiley Periodicals, Inc.     

Use of Large‐Scale Electrokinetic and ZVI Treatment for Chlorinated Solvent Remediation at an Active Industrial Facility

The combination of electrokinetic and zero‐valent iron (ZVI) treatments were used to treat soils contaminated with chlorinated solvents, including dense nonaqueous phase liquid (DNAPL), at an active industrial site in Ohio. The remediation systems were installed in tight clay soils under truck lots and entrances to loading docks without interruption to facility production. The electrokinetic system, called Lasagna^TM, uses a direct current electrical field to mobilize contaminant via electroosmosis and soil heating. The contaminants are intercepted and reduced in situ using treatment zones containing ZVI. In moderately contaminated soils around the Lasagna^TM‐treated source areas, a grid of ZVI filled boreholes were emplaced to passively treat residual contamination in decades instead of centuries. The remediation systems were installed below grade and did not interfere with truck traffic during the installation and three years of operation. The Lasagna^TM systems removed 80 percent of the trichloroethylene (TCE) mass while the passive ZVI borings system has reduced the TCE by 40 percent. The remediation goals have been met and the site is now in monitoring‐only mode as natural attenuation takes over. © 2014 Wiley Periodicals, Inc.     

A Study of the Use of Alfalfa (Medicago sativa L.) for the Phytoremediation of Organic Contaminants in Soil

This article presents the results of a study that was conducted to determine the effectiveness of using alfalfa (Medicago sativa L.) to enhance the phytoremediation of three different types of chemical contaminants. The chemicals studied were trinitrotoluene (TNT), the polycyclic aromatic hydrocarbon (PAH) pyrene, and the polychlorinated biphenyl (PCB) Aroclor 1248. Experiments were conducted using soils that contained high and low organic matter content. The results indicated that recoveries of pyrene and TNT from soil were highly dependent on the soil organic matter content, while the recovery of PCB was not. Significantly low levels of pyrene and TNT were recovered from all treatments in the soil with 6.3 percent organic matter content compared to recovery levels found in soil with 2.6 percent organic matter. The presence of alfalfa plants had a significant effect on the transformation of TNT and PCB in the low organic matter content soil only and had no effect on the fate of pyrene. In the low organic matter soil, only 15 percent and 17 percent of the initial TNT and PCB levels, respectively, were transformed in the unplanted control soils compared to 66 percent and 77 percent in the alfalfa planted pots. In both soil types, pyrene dissipation could not be attributed to the presence of alfalfa plants. Overall, it was concluded that under high soil organic matter conditions, adsorption and covalent binding to the soil organic matter appeared to be the dominant force of pyrene and TNT removal. The effectiveness of using alfalfa to enhance PCB and TNT transformations was more significant in the lower organic matter soil; thus phytoremediation had a greater effect in soils with lower organic matter content. © 2001 John Wiley & Sons, Inc.     

Phytoremediation in subtropical Hawaii—A review of over 100 plant species

Phytoremediation is an emerging remediation technology that utilizes plants and microbes to clean up contaminated air, soil, and water. Tropical and subtropical environments have an advantage in that long plant‐growing seasons and increased soil temperature can accelerate phytoremediation processes. Various contaminated sites in Hawaii have been addressed using this technology. In this article, work progress and advances of phytoremediation are briefly reviewed and exemplified with seven chemically contaminated sites in Hawaii. The investigations were performed for one or more of the following remediation needs: explosive residues, hydrocarbons, pesticide residues, soil stabilization, and slaughterhouse wastewater. In this unique article, studies of testing of over 100 plant species for remediation are reviewed and documented. The general trend leads one to consider that salt‐ and/or drought‐tolerant plants can bear other potential stress‐inducing conditions. © 2004 Wiley Periodicals, Inc.     

Advanced site diagnostic tool 3D‐CSIA for in situ remediation

In situ remediation is inherently considered “green remediation.” The mechanisms of destruction by in situ technologies, however, are often unseen and not well understood. Further, physical effects of amendment application affect concentration data in an identical manner as the desired reactive mechanism. These uncertainties have led to the weight‐of‐evidence approach when proving viability: multiple rounds of data collection, bench studies, pilot studies, and so on. Skipping these steps has resulted in many failed in situ applications. Traditional assessment data are often tangential to the desired information (e.g., “Is contaminant being destroyed or just being pushed around and diluted?” and “What is the mechanism of the destruction and can it be monitored directly?”). An advanced site diagnostic tool, “Three‐Dimensional Compound Specific Stable Isotope Analysis” (3D‐CSIA), can assess the viability of in situ technologies by providing definitive data on contaminant destruction that are not concentration‐related. The 3D‐CSIA tool can also locate source zones and apportion remediation cost by identifying plumes of different isotope signatures and fractionation trends. Further, use of the 3D‐CSIA tool allows remediation professionals to evaluate effectiveness of treatment and make better decisions to expedite site closure and minimize costs. This article outlines the fundamentals of advanced site diagnostic tool 3D‐CSIA in detail, and its benefit is highlighted through a series of case studies at chlorinated solvent–contaminated sites. © 2010 Wiley Periodicals, Inc.     

Application of the rescue number to the evaluation of remediation technologies for contaminated ground

An improved rescue number, RN_SOIL, which is an indicator for evaluating remediation technologies for contaminated ground that is based on both the risk and the remediation cost, is proposed as a tool of risk communication. The risk posed by contaminated ground is indicated by the figure of treatment priority at time t, FTP(t), which represents the human health risk as the number of people affected by the contaminated ground at time t during the remediation process. The calculation of the value of FTP(t) is based on exposure to contaminants that have migrated through environmental media from the contaminated ground, and is estimated by using a CalTOX model and the Monte Carlo method. The integration of FTP(t) with time, which represents the cumulative number of people affected by the contaminated ground, is used to estimate the performance of individual remediation technologies in risk reduction. The figure of unprocessibility for waste (FUW), which represents difficulties in remediation, is expressed as the remediation cost. FUW is estimated by using actual costs per unit volume of remediated soil. As an overall performance value, the rescue number for each remediation technology for contaminated ground (RN_SOIL) is calculated by multiplication of the integral FTP(t) by FUW. Smaller values of RN_SOIL are judged to indicate a better technology. The rescue index (RI), calculated as the ratio of the reduction of the integral FTP(t) to FUW, indicates the cost-effectiveness of the remediation technologies. Successful estimation of the indices (FTP(t), integral FTP(t), FUW, RN_SOIL and RI) demonstrate the usefulness of these indices in risk communication.Part of this paper was presented at 13th meeting of Japan Society of Waste Management Experts (2002)     

Injecting remediation compounds—How you inject is equally as important as what you inject

The injection of remediation compounds has rapidly become a widely accepted approach for addressing contaminated sites. One of the most fundamental questions surrounding the use of in situ remediation has been “What compound are you injecting at your site?” With the advances in the industry's understanding and acceptance of the in situ remediation process remediation professionals are now asking a follow‐up question that has become equally important to the success of a project: “How are you injecting a compound at your site?” This article discusses advances in field applications for in situ remediation and injecting remediation compounds. © 2003 Wiley Periodicals, Inc.     

Review of in situ remediation technologies for lead,zinc, and cadmium in soil

This article presents a review of in situ technologies for the remediation of soils contaminated with lead, zinc, and/or cadmium. The objective of this review is to assess the developmental status of the available in situ technologies and provide a general summary of typical applications and limitations of these technologies. The literature review identified seven in situ remediation technologies—solidification/stabilization, vitrification, electrokinetic remediation, soil flushing, phytoextraction, phytostabilization, and chemical stabilization. These technologies were considered for their ability to meet a specific set of remediation objectives under a range of conditions. Each of these technologies has both strengths and weaknesses for addressing particular remedial situations discussed in the article for each of the technologies. A general summary of which technologies are most applicable to common remedial scenarios is also provided. © 2004 Wiley Periodicals, Inc.     

Microbially Mediated In Situ Desorption Accelerates Remediation of Large Gasoline Product Plume

Remediation of a large separate‐phase hydrocarbon product and associated dissolved‐phase gasoline plume was accelerated by coupling multiphase extraction with in situ microbial stimulation. At the beginning of remediation activities, the separate‐phase hydrocarbon plume extended an estimated seven acres with product thickness measuring up to 2.1 feet thick. Within 18 months after beginning extraction, reduction of gasoline constituents in groundwater became asymptotic and measureable product disappeared from the upgradient source area. At that time, the remediation team initiated a program of limited in situ anaerobic bioremediation with the goal of stimulating production of natural surfactants from native microbes to release petroleum from the soil matrix. Groundwater concentrations of gasoline constituents increased gradually over the next three years, improving recovery without biofouling the pump‐and‐treat infrastructure. Using this approach, the groundwater component of the remedy was completed in less than five years, substantially less than the 10 years to 15 years predicted by modeling. This strategy demonstrated a more sustainable approach to remediation, reducing electrical usage by an estimated 800 megawatt hours, reducing infrastructure requirements, and preserving an estimated 150 million gallons of groundwater for this arid agricultural area. © 2014 Wiley Periodicals, Inc.     

Performance evaluation of an in situ source area combined remedy for the remediation of commingled chlorinated ethanes and ethenes

The chlorinated volatile organic compounds (CVOCs), tetrachloroethene (PCE), trichloroethene (TCE), and 1,1,1‐trichloroethane (1,1,1‐TCA), often found as commingled contaminants of concern (COCs) in groundwater, can degrade via a variety of biotic and abiotic reductive pathways. In situ remediation of a groundwater contaminant source area containing commingled 1,1,1‐TCA, PCE, and TCE was conducted using a combined remedy/treatment train approach. The first step was to create geochemically reducing conditions in the source area to degrade the CVOCs to lesser chlorinated CVOCs (i.e., 1,1‐dichloroethane [1,1‐DCA], 1,1‐dichlorethene [1,1‐DCE], cis‐1,2‐dichoroethene [cis‐1,2‐DCE], and vinyl chloride [VC]) via enhanced reductive dechlorination (ERD). Carbon substrates were injected to create microbial‐induced geochemically reducing conditions. An abiotic reductant (zero‐valent iron [ZVI]) was also used to further degrade the CVOCs, minimizing the generation of 1,1‐DCE and VC, and co‐precipitate temporarily mobilized metals. An in situ aerobic zone was created downgradient of the treatment zone through the injection of oxygen. Remaining CVOC degradation products and temporarily mobilized metals (e.g., iron and manganese) resulting from the geochemically reducing conditions were then allowed to migrate through the aerobic zone. Within the aerobic zone, the lesser chlorinated CVOCs were oxidized and the solubilized metals were precipitated out of solution. The injection of a combination of carbon substrates and ZVI into the groundwater system at the site studied herein resulted in the generation of a geochemically reducing subsurface treatment zone that has lasted for more than 4.5 years. Mass concentrations of total CVOCs were degraded within the treatment zone, with near complete transformation of chlorinated ethenes and a more than 90 percent reduction of CVOC mass concentrations. Production of VC and 1,1‐DCE has been minimized through the combined effects of abiotic and biological processes. CVOC concentrations have declined over time and temporarily mobilized metals are precipitating out of the dissolved phase. Precipitation of the dissolved metals was mitigated using the in situ oxygenation system, also resulting in a return to aerobic conditions in downgradient groundwater. Chloroethane (CA) is the dominant CVOC degradation product within the treatment zone and downgradient of the treatment zone, and it is expected to continue to aerobically degrade over time. CA did not accumulate within and near the aerobic oxygenation zone. The expectations for the remediation system are: (1) the concentrations of CVOCs (primarily in the form of CA) will continue to degrade; (2) total organic carbon concentrations will continue to decline to pre‐remediation levels; and, (3) the groundwater geochemistry will experience an overall trend of transitioning from reducing back to pre‐remediation mildly oxidizing conditions within and downgradient of the treatment zone.     

Phytoremediation of Selected Explosives

The phytoremediation of trinitrotoluene (TNT), nitroglycerine (NG) and pentaerytritoltetranitrate (PETN) using in vitrocultures of Rheum palmatum, Saponaria officinalisand Populus simonii were studied. All above mentioned explosives were degradated to less toxic products and finally probably bound to the cell wall or further involved in the metabolism. The formation of trinitrobenzene (TNB) during degradation of TNT which is a product of alternative degradation pathway was found too.     

Ten years later: The progress and future of integrating sustainable principles,practices, and metrics into remediation projects

In 2009, the Sustainable Remediation Forum released a white paper entitled “Integrating sustainable principles, practices, and metrics into remediation projects” (Ellis & Hadley, 2009, Remediation, 19, pp. 5–114). Sustainable remediation was a relatively new concept, and the white paper explored a range of approaches on how sustainability could be integrated into traditional remediation projects. This paper revisits the 2009 white paper, providing an overview of the early days of the evolving sustainable remediation practice and an assessment of the progress of sustainable remediation over the last 10 years with a primary focus on the United States. The current state of the sustainable remediation practice includes published literature, current practices and resources, applications, room for improvement, international progress, the virtuous cycle that applying sustainable remediation creates, and the status of the objectives cited in the 2009 white paper. Over the last decade, several sustainable remediation frontiers have emerged that will likely be a focus in advancing the practice. These frontiers include climate change and resiliency, weighting and valuation to help better consolidate different sustainable remediation metrics, programmatic implementation, and better integration of the societal impacts of sustainable remediation. Finally, as was the case for the 2009 white paper, this paper explores how sustainable remediation may evolve over the next 10 years and focuses on the events and drivers that can be significant in the pace of further development of the practice. The events and drivers include transformation impacts, societal influences, and the continued development of new technologies, approaches, and tools by remediation practitioners. The remediation industry has made significant progress in developing the practice of sustainable remediation and has implemented it successfully into hundreds of projects. While progress has been significant, an opportunity exists to implement the tenets of sustainable remediation on many more projects and explore new frontiers to help improve the communication, integration, and derived benefits from implementing sustainable remediation into future remediation projects.     

Low‐concentration hydrogen peroxide decontamination for Bacillus spore contamination in buildings

Remediation and recovery efforts after a release of Bacillus anthracis (anthrax) spores may be difficult and costly. In addition, response and recovery technologies may be focused on critical resources, leaving the small business or homeowner without remediation options. This study evaluates the efficacy of relatively low levels of hydrogen peroxide vapor (HPV) delivered from off‐the‐shelf equipment for the inactivation of Bacillus spores within an indoor environment. Decontamination evaluations were conducted in a house using both Bacillus atrophaeus var. globigii (Bg; as surrogates for B. anthracis) inoculated on the carpet and galvanized metal as coupons and Geobacillus stearothermophilus (Gs) as biological indicators on steel. The total decontamination time ranged from 4 to 7 days. Using the longer exposure times, low concentrations of HPV (average levels below 20 parts per million) effectively inactivated Bg and Gs spores on the materials tested. The HPV was generated with commercial humidifiers and household‐strength hydrogen peroxide solutions. The presence of home furnishings did not have a significant impact on HPV efficacy. This simple, inexpensive, and effective decontamination method could have significant utility for remediation following a B. anthracis spore release, such as following a terrorist attack.     

In Situ Remediation of 1,4‐Dioxane Using Electrical Resistance Heating

Recent regulatory changes need more challenging treatment goals for 1,4‐dioxane. However, significant treatment limitations exist in part due to the high solubility and low Henry's law constant of 1,4‐dioxane. Two case studies are reported with substantial 1,4‐dioxane concentration reductions through in situ thermal remediation via electrical resistance heating (ERH). Concentration reductions greater than 99.8 percent of 1,4‐dioxane have been observed in the field using ERH. Concentrations of 1,4‐dioxane in air and steam extracted by an ERH vapor recovery system have also been evaluated. Laboratory studies were conducted to further understand the mechanisms that enable ERH remediation of 1,4‐dioxane. Vapor liquid equilibrium studies in water and soil were conducted and utilized to develop an ERH treatment cost model for 1,4‐dioxane. Existing field data were correlated to the 1,4‐dioxane treatment cost model. Field observations and laboratory testing indicate steam stripping that occurs through ERH remediation is an effective treatment method for 1,4‐dioxane. ©2015 Wiley Periodicals, Inc.     

Phytoremediation: Modeling removal of TNT and its breakdown products

Contamination of soil and groundwater by trinitrotoluene (TNT) is a widespread problem confronting military bases and ammunition manufacturing facilities throughout the United States. Phytoremediation provides a promising treatment of TNT-contaminated groundwater and wastewater because many plants contain the necessary enzymes to degrade explosives such as TNT. Two phytoremediation methods are proposed in this article: controlled reactors and constructed wetlands. Controlled reactors provide greater control of operating parameters, a reduced possibility of contaminant migration, control of animals feeding on the plants, and minimization of competition from other plant species. Constructed wetlands have relatively low capital costs, and the wetland becomes a desirable ecological resource. Because cost, as opposed to reactor size, appears to be the most significant factor for military base cleanup, this project focused on the constructed wetland approach. To estimate the disappearance of TNT and its breakdown products from a constructed wetland, a first-order, nonreversible reaction, plug-flow, finite-difference model was developed. Batch scale experiments were conducted to define disappearance kinetics for individual chemical species. The results of the model suggest that reasonably sized wetlands may be used to treat a wastestream with an influent TNT concentration of 2.25 ppm at flow rates ranging from 10 to 5,000 gpm. Economic comparisons to other published costs for competing technologies are promising.