The Use of Electrokinetics for Hazardous Waste Site Remediation

The Superfund Innovative Technology Evaluation (SITE) program was authorized as part of the 1986 amendments to the Superfund legislation. It represents a joint effort between U.S. EPA’s Office of Research and Development and Office of Solid Waste and Emergency Response. The program is designed to assist and encourage the development of waste treatment technologies that would contribute to more solutions to our hazardous waste problems.

Recently, EPA, through the SITE program, issued a work assignment to assess the “stateof- the-art” of electroklnetically enhanced contaminant removal from soils. Prior research efforts, both laboratory and field, have demonstrated that electroosmosis has the potential to be effective In facilitating the removal of certain types of hazardous wastes from soils. Particularly encouraging results have been achieved with inorganics in fine-grained soils where more traditional removal alternatives are less effective.

Although the results of various studies suggest that electrokinetics is a promising technology, further testing Is needed at both the laboratory and field levels to fully develop this technology for site remediation. A conceptual test program Is presented based on best available data which incorporates system design and operating parameters used in previous applications of this technology In the use of electrokinetics treatment as a remediation technique at hazardous waste sites.     

Treatment Technologies For Hazardous Wastes: Part IV A Review of Alternative Treatment Processes for Metal Bearing Hazardous Waste Streams

The U.S. Congress and the U.S. Environmental Protection Agency believe that treatment and recovery techniques should be given maximum priority when considering methods for managing the nation's generated hazardous waste. A prohibition for the disposal of certain categories of hazardous wastes either directly onto or into the land without being treated to an accepted degree prior to such disposal practice has been promulgated.¹ Wastes containing toxic metals and cyanide complexes have been selected as a group to be restricted. Due to the high generation rate associated with this category, a large capacity of waste treatment processing will be required. Existing and emerging treatment alternatives which are or have the potential to be employed for waste treatment of metal bearing wastes are presented in this paper.     

Flow rates and compositions of incinerated waste streams in the United States.

The quantity and composition of RCRA hazardous wastes incinerated during 1986 were examined using the National Hazardous Waste Survey. This Survey, collected for U.S. EPA by the Research Triangle Institute, is the most extensive examination of hazardous waste generation and management available. The survey data show that although a wide variety of hazardous wastes were treated by incineration, more than 75 percent of incinerated waste streams were from chemical manufacturing. The survey data also show that more than 90 percent of the incinerated wastes were treated by incinerators located at the facility generating the waste. Despite the predominance of a single industrial sector in generating incinerated hazardous wastes, the compositional profile of the wastes is far from uniform. To illustrate this variability, the metals and chlorine content of the wastes are reported along with the sources of the metal and chlorine loadings.     

Refinery Sludge Treatment/Hazardous Waste Minimization Via Dehydration and Solvent Extraction

Abstract

The patented Carver-Greenfield (C-G) Process®, a combination of dehydration and solvent extraction treatment technologies, has a wide range of uses in separating hydrocarbon solvent-soluble hazardous organic contaminants (indigenous oil) from sludges, soils, and industrial wastes. As a result of this treatment, the products from a C-G Process facility are: ? Clean, dry solids which are typically suitable for disposal in nonhazardous landfills;

? Water which is treatable in an industrial or Publicly Owned Treatment Works (POTW) wastewater treatment facility;

? Extracted indigenous oil containing hydrocarbon soluble contaminants which may be recycled or reused or disposed of at less cost because its volume is smaller than the original waste feed.

The C-G Process was demonstrated on spent oily drilling fluids as part of the U.S. Environmental Protection Agency Superfund Innovative Technology Evaluation (SITE) Program. This paper summarizes the use of the C-G Process for economical treatment and minimization of hazardous refinery wastes, reviews the SITE program results, and describes extending the C-G Process technology to treatment of other wastes. Estimated treatment costs are presented.     

The "Least Favored Method"—A Primer on the RCRA Land Disposal Regulations

In May of 1990 the U.S. Environmental Protection Agency (EPA) completed a four year long series of rulemakings on land disposal of over. 450 hazardous wastes regulated under the Resource Conservation and Recovery Act (RCRA). The new regulations stipulate that hazardous wastes may not be disposed of on land—if at all—unless they are first treated in a prescribed manner. The Land Disposal Regulations (LDRs) will change disposal requirements for approximately 41 million tons of hazardous waste annually, at a cost to the regulated community of over a billion dollars. Despite EPA’s efforts to educate industry, the LDRs remain a source of confusion for many. This article is intended to clear up at least some of the confusion by providing an overview of the regulations and the decision-making processes which occurred during the four years of EPA rulemakings and, more recently, in the courts.     

Conversion of chromium-containing solid wastes into value-added products through a plasma-assisted aluminothermic process

Chromium-containing solid wastes have been generated by chemical and leather/tanning industries, and the management and proper disposal of the same wastes have been challenging tasks. A significant fraction of these wastes contains chromium compounds with chromium present in the hexavalent (Cr⁺⁶) form, which is hazardous to human beings, animals, and ecosystems. Since these wastes are discarded largely without proper treatments, soil and groundwater get contaminated and they can cause several health issues to human beings. Conventional methods developed to convert hazardous Cr⁶⁺ to Cr³⁺/Cr metal either generate secondary toxic wastes and unwanted by-products and/or are time-consuming processes. In this work, a plasma-assisted aluminothermic process is developed to convert the toxic waste into non-toxic products. The waste was mixed with aluminium powder and subjected to transferred arc plasma treatment in a controlled air atmosphere. Chemical analysis and Cr leachability studies of the waste material prior to plasma treatment have shown that it is highly toxic. Analysis of the products obtained from the plasma treatment showed that Cr and Fe present in the waste could be recovered as a metallic mixture as well as oxide slag, which were found to be non-toxic. Easy separation of the metallic fraction and the slag from the treated product is one of the merits of this process. Besides converting chromium-containing toxic waste to non-toxic materials, the process is rapid and recovers the metals from the waste completely.

     

Thermal Encapsulation of Metals in Superfund Soils

Abstract

Superfund sites frequently contain both heavy metals and organic hazardous waste. If not properly controlled, the metals may be changed to a more leachable form and may also be emitted to the atmosphere via the exhaust stack. This paper documents a batch kiln R&D test program to solve these metal-related problems. It was performed under the U.S. EPA’s SITE (Superfund Innovative Technology Evaluation) Emerging Technology Program. Allis Mineral Systems has developed the Thermal Encapsulation Process. Metals with limits set by EPA’s TCLP (Toxicity Characteristic Leaching Procedure) test and BIF (boiler and industrial furnace) stack emission regulations, such as cadmium, chromium, and lead, are the initial target of this process. This process, while unproven in these areas, may also apply to mixed waste (EPA hazardous waste/low-level radioactive wastes) and may also benefit commercial hazardous waste or Superfund thermal treatment systems. The results of the SITE tests were positive: strong, durable nodules were produced with excellent crush strength and improved resistance to leaching. Feed preparation, particularly control of moisture content, was found to be a key element in initiation of agglomeration. A good correlation was found between decreasing TCLP metals leachate levels and increasing crush strength.     

A Model Analysis of Metal Partitioning

The 1984 Amendments to the Solid Waste Act require that wastes listed under the Resource Conservation and Recovery Act (RCRA) be analyzed to assess the feasibility of further banning from land disposal. Incineration is expected to be used more often for disposing of either the banned wastes directly or the residues of various treatment processes. Incineration of hazardous wastes, municipal wastes and industrial sludges produces some extent of trace metals. This paper provides a preliminary model concept for analyzing metal partitioning during incineration. The paper concludes that a model for predicting metal partitioning phenomena is feasible and could reduce costs in conducting metal emission testing in the field.     

Recent advances in the application of silica nanostructures for highly improved water treatment: a review

The demand for high-quality safe and clean water supply has revolutionized water treatment technologies and become a most focused subject of environmental science. Water contamination generally marks the presence of numerous toxic and harmful substances. These contaminants such as heavy metals, organic and inorganic pollutants, oil wastes, and chemical dyes are discharged from various industrial effluents and domestic wastes. Among several water treatment technologies, the utilization of silica nanostructures has received considerable attention due to their stability, sustainability, and cost-effective properties. As such, this review outlines the latest innovative approaches for synthesis and application of silica nanostructures in water treatment, apart from exploring the gaps that limit their large-scale industrial application. In addition, future challenges for improved water remediation and water quality technologies are keenly discussed.

     

Treatment Technologies For Hazardous Wastes: Part III Treatment Technologies for Corrosive Hazardous Wastes

In this paper, the authors present generation and treatment information for corrosive hazardous wastes (EPA Hazaradous Waste Codes D002 and K062). The authors discuss the state of the art for several treatment trains used to process specific types of corrosive waste. Treatment trains incorporate various unit processes selected from but not limited to the following: neutralization, filtration, carbon adsorption, biological oxidation, distillation, air flotation, and incineration. Unit processes are selected to form trains according to the corrosive characteristics of each individual waste stream. The treatment processes discussed are proposed to be used instead of landfills for disposal of corrosive waste.     

Hazardous Waste Minimization: Part IX Waste Minimization in the Automotive Repair Industry

Waste minimization in the automotive repair industry is characterized by the large numbers of small quantity generators (SQG) producing solvent, alkaline and detergent hazardous wastes. On-site management of multiple processes which vary depending on the size of shop make the administration of hazardous waste policies particularly complex. This paper presents the quantities and types of hazardous materials typically produced. Guidelines are presented to allow generators to organize a waste minimization program.     

Avoiding Land Disposal of Hazardous Waste

In response to a growing societal mandate, land disposal of hazardous wastes is gradually being replaced by treatment technologies. This shift to "alternative technologies" is the result of the impacts of past land disposal practices on other environmental media (groundwater, surface water, and air). A prime motivation for adopting alternatives to land disposal is to eliminate these cross-media impacts. Alternative technologies, however, can themselves have cross-media environmental impacts which must be recognized and addressed before such technologies are extensively applied. This paper discusses hazardous waste constituents, common disposal practices, alternative technologies currently being applied, possible cross-media environmental impacts of the alternative technologies, and proposed methods of mitigating these environmental impacts. Case studies from uncontrolled hazardous waste sites and industrial operations are used to illustrate the application of alternative technologies. Case studies include the application of waste treatment technologies as well as the adoption of waste minimization techniques.     

Deactivation of the Vanadia Catalyst in the Selective Catalytic Reduction Process

Results are summarized of a comprehensive study of the effects on the SCR process of all major possible poisons encountered in the combustion gases from U.S. coals. A general rule evolved from this study Is that the effect of the additive on the catalyst activity Is directly related to the basicity of the additive; poisoning Is caused by the basicity. Quantitative effects are presented, while a qualitative summary is given as follows: strong poisons-alkali metal oxides; weak poisons-oxides of alkaline earth metals, arsenic, lead phosphorus and chlorides of strong alkaline metals. SO₂ is a promoter due to its acidity. HCI, although acidic, reacts with both NH₃ (forming NH₄CI) and V₂O₅ (forming VCI₂ and VCI₃) and consequently strongly deactivates the SCR reaction.

A summary is also given for a theoretical and experimental study of the monolithic honeycomb reactor using both undoped and poison-doped catalysts. The results showed that the reactor performance can be predicted directly from the intrinsic catalyst activity through a model.     

Case Studies of Minimizing Plating Bath Wastes in the Electronics Products Industry

In this paper the authors report on the results of case studies carried out under the sponsorship of the U.S. EPA to determine the effectiveness of four processes designed to reduce the amount of hazardous waste from plating operations. Data reported are based on the results of actual on-site sampling of the processes and encompass effectiveness, environmental, and economic considerations. Two of the case studies evaluating the use of sodium borohydride reduction as a substitute for lime/ferrous sulfate precipitation, found that the technology was a viable substitute in one case and was marginally acceptable in another. Another case study, involving carbon adsorption removal of organic contaminants from plating bath wastes, found that this technology significantly reduced both disposal costs and waste volume. A final case study of electrolytic recovery indicated that while acid copper electroplating rinses are amenable to electrolytic recovery, other metal-bearing rinses, such as those from solder (tin/lead) plating or etching are less appropriate.     

Automated Economic Analysis Model For Hazardous Waste Minimization

Abstract

The U.S. Army has established a policy of achieving a 50 percent reduction in hazardous waste generation by the end of 1992. To assist the Army in reaching this goal, the Environmental Division of the U.S. Army Construction Engineering Research Laboratory (USACERL) designed the Economic Analysis Model for Hazardous Waste Minimization (EAHWM). The EAHWM was designed to allow the user to evaluate the life cycle costs for various techniques used in hazardous waste minimization and to compare them to the life cycle costs of current operating practices. The program was developed in C language on an IBM compatible PC and is consistent with other pertinent models for performing economic analyses. The potential hierarchical minimization categories used in EAHWM Include source reduction, recovery and/or reuse, and treatment. Although treatment is no longer an acceptable minimization option, its use is widespread and has therefore been addressed in the model. The model allows for economic analysis for minimization of the Army’s six most important hazardous waste streams. These include, solvents, paint stripping wastes, metal plating wastes, industrial waste-sludges, used oils, and batteries and battery electrolytes. The EAHWM also includes a general application which can be used to calculate and compare the life cycle costs for minimization alternatives of any waste stream, hazardous or non-hazardous. The EAHWM has been fully tested and implemented in more than 60 Army installations in the United States.     

危险废物处理技术进展及若干建议

较系统地论述了国内固体废物的目前状况、产量,分析了一些典型危险废物处理过程中存在的主要问题和解决方法,提出了深人开展危险废物处理与资源化研究的方向,并给出了环保部门应对危险废物进行处理的建议。     

Treatment of Nonhazardous Petroleum-Contaminated Soils by Thermal Desorption Technologies

Spills, leaks, and accidental discharges of petroleum products have contaminated soil at thousands of sites in the United States. One remedial action technique for treating petroleum contaminated soil is the use of thermal desorption technologies.

This paper describes key elements of the U.S. Environmental Protection Agency report titled “Thermal Desorption Applications Manual for Treating Nonhazardous Petroleum Contaminated Soils.”¹ The applications manual describes the types, mechanical and operating characteristics of thermal desorption technologies that are commercially available to treat petroleum-contaminated soils. It also provides step-by-step procedures to rate the critical success factors influencing the general applicability of thermal desorption at a particular site. These factors include site, waste and soil characteristics, regulatory requirements, and process equipment design and operating characteristics. Procedures are provided to determine the types of thermal desorption systems that are most technically suitable for a given application and to determine whether on-site or off-site treatment is likely to be the most cost-effective alternative. Key factors that determine process economics are identified, and estimated cost ranges for treating petroleum-contaminated soils are presented. Spreadsheets are provided that can be used for performing cost analyses for specific applications.

The aforementioned report is applicable only to the treatment of petroleum-contaminated soils that are exempt from being classified as hazardous wastes under the Resource Conservation and Recovery Act (RCRA) or as toxic materials under the Toxic Substances Control Act (TSCA). Although much of the technical discussion in this paper is applicable to the treatment of both nonhazardous and hazardous ortoxic materials, permitting requirements and treatment costs are significantly different forthe individual categories of waste materials.     

生活垃圾固结技术及其安全性研究

针对生活垃圾产生量逐年增多的趋势，采用新型固化技术对陈腐生活垃圾进行固结，并对其固结效果和安全性进行研究。研究结果表明：本固结技术可使生活垃圾固结体28d强度达38MPa以上，其耐久性能诸如抗冻性能、耐水性能、抗干湿循环能力和抗硫酸盐侵蚀性能较为优越。并且其固结体重金属溶出量亦满足国家标准，即生活垃圾中的重金属离子得到有效的束缚和稳定固化。     

生活垃圾固结技术及其安全性研究

针对生活垃圾产生量逐年增多的趋势,采用新型固化技术对陈腐生活垃圾进行固结,并对其固结效果和安全性进行研究.研究结果表明:本固结技术可使生活垃圾固结体28 d强度达38 MPa以上,其耐久性能诸如抗冻性能、耐水性能、抗干湿循环能力和抗硫酸盐侵蚀性能较为优越.并且其固结体重金属溶出量亦满足国家标准,即生活垃圾中的重金属离子得到有效的束缚和稳定固化.