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Designed and built by the National Environmental Evaluation and Remediation Consortium, the Environmental Knowledge and Assessment Tool (EKAT™) at www.ekat-tool.com is a web-based project management and decision-support tool to identify, research, and evaluate environmental and pollution prevention options, and safety-related issues for materials used in products and systems. The original concept of EKAT was to help Marine Corps Systems Command integrate environmental requirements into systems acquisition programs. The tool can also benefit federal and state agencies, communities, and businesses. EKAT contains information on technical and regulatory requirements and serves as a resource center with links to references, tools, and databases to assist in research efforts and minimize unintentional safety and environmental effects associated with product development or use. Features include project management and organizational capability, collaboration within project teams or the EKAT community, and communication through threaded discussions. EKAT serves as a preliminary environmental screening tool for regulatory requirements and issues of concern. The user may enter or download lists of chemicals that she or he may have obtained from material safety data sheets for products typically used in activities and operations; these chemicals can then be screened against 14 lists of federally regulated chemicals. Some of the federal lists for which the user's entered chemicals are screened against include the Clean Air Act, the Clean Water Act, the Resource Conservation and Recovery Act, the Emergency Planning and Community Right-to-Know Act, various lists of carcinogenic substances, and more. Users may also get help estimating emissions from equipment and manufacturing processes, or review information resource documents and research guides, which provide additional environmental information and resources in a user-friendly format. All regulatory information, for environmental, health, and safety issues found within EKAT, is based on United States federal laws and regulations, to which links can be found throughout. Links to sources of additional information, other than U.S. governmental web sites or resources, may also be found in EKAT. © 2007 American Institute of Chemical Engineers Environ Prog, 2007

The oil industry contributes to contamination of groundwater and aquifers beneath refineries and oil terminals. The successful remediation of a contaminated site requires understanding both the hydrogeology and the nature and extent of contamination. The physical–chemical and biological mechanisms that govern contaminant release, transport and fate in soils, sediments, and associated fluid phases must be understood and quantified. In addition, understanding the flow and entrapment of nonaqueous phase liquids (NAPLs) including lighter-than-water nonaqueous phase liquids (LNAPLs) in contaminated aquifers is important for the effective design of the recovery and remediation schemes. Current remedial technologies and risk assessment techniques to remediate former oil refinery sites contaminated by NAPLs are described in this paper. Emphasis is given to the most promising remediation techniques such as pump-and-treat, on-site bioremediation, phytoremediation, in situ soil washing, and thermal-based technologies, such as steam-enhanced extraction. Some enhancements to pump-and-treat techniques such as solvent flushing, polymer enhanced flushing, and air stripping are also discussed. Finally, important risk-based cleanup criteria associated with contaminated soil at refineries are presented. © 2005 American Institute of Chemical Engineers Environ Prog, 2005

Tertiary butyl mercaptan (TBM) is a malodorant that is added to natural gas in small quantities to aid in its detection. The objective of this study was to investigate the degradation of TBM under aerobic conditions. A bacterial culture was found that grew well on TBM in liquid minimal media under aerobic conditions. The doubling time was about 98 h at 30° C. In cultures where iron fillings were added, the growth rate increased and the doubling time was 44 h. In studies with manganese dioxide and potassium permanganate, TBM was oxidized chemically at rates that were rapid compared to those in the microbiological studies. Soil microcosms containing soil, water, and TBM were set up using two different soils and their headspace was sampled during a 62-day period of study. In the first set, there was significantly greater reduction in TBM and production of carbon dioxide in the treatments compared to that of the sterilized controls. An intermediate product di-tertiary-butyl disulfide (DTBD) was identified. The experimental results show that TBM appears to be biodegradable in soil-water systems under aerobic conditions.

The waste generated by aircraft deicing operations represents a threat to the environment arising from the high biological oxygen demand of propylene and ethylene glycols and the toxicity associated with some of the additives, such as the corrosion inhibitor benzotriazole. To date, there have not been any reports of wastewater treatment alternatives that completely degrade the toxic triazole components in the deicing waste. Constructed wetlands and land application can potentially take advantage of vegetation in two different ways: enhancement of biodegradation of glycols by the root-bacteria symbiosis and transformation of benzotriazoles by plant enzymatic activities. In a plant treatment system, phytotransformation of the triazoles can follow a conventional biological wastewater treatment, which can be used for glycol degradation. This paper reviews the main aspects of aircraft deicing waste treatment, outlines the results from successful applications of constructed wetlands to treat glycol-rich waste, and summarizes the experimental basis that demonstrates the benefits of using vegetation for decontamination of the main components of deicing waste. © 2004 American Institute of Chemical Engineers Environ Prog, 2005

Plants have the potential for aiding in situ remediation of contaminated soil and groundwater by promoting microbial growth in the rhizosphere. Microbial populations vary in response to the presence of oxygen, water and metabolizable carbon sources. Plants are able to provide a favorable environment for microbe growth by providing a plant pathway for oxygen transfer to the soil, transferring water from saturated to unsaturated soil, and supplying supplemental substrate in the form of root exudates and decaying root hairs. Models of the physical, chemical, and biological relationships in the rhizosphere are reported. Simulation results are presented for a hypothetical vegetative buffer zone over a shallow aquifer. The fate of atrazine is simulated in order to investigate the effects of rainfall, evapotranspiration, atrazine uptake by plants, and atrazine adsorption to root surfaces on atrazine concentration at the downstream edge of the vegetative buffer zone.

The role of aggregates and their characteristics on bioremediation in soil has received very little attention. In this investigation, the contaminated aggregates bioremediation (CAB) model has been developed and simulated to analyze the bioremediation of soil and water in the aggregates. The model equations consist of a system of three non-linear partial differential equations. Dimensional analysis of the equations has been performed. Sensitivity analysis conducted by numerically solving them has demonstrated the effects of aggregate radius, partition coefficient, and initial contaminant concentration on the time and mechanism of remediation. The rates of diffusion of substrate and oxygen, and the biodegradation-rate have been found to be the controlling mechanisms for remediation in the aggregates.

A mathematical model has been developed for in situ biodegradation of contaminants in a soil bed. The model equations comprise three convection-dispersion partial differential equations and one ordinary differential equation. Dimensional analysis of the model equations has been performed, and solution of these equations has been conducted by the newly-developed three-point backward finite difference method. The effects of insufficient oxygen supply, growth of biomass and resistance to contaminant migration on the rate of biodegradation have been examined by numerically simulating the dynamic behavior of in situ biodegradation processes. The results of numerical simulation indicate that the rate of biodegradation of contaminants in soil may be constrained not only by insufficient oxygen supply, but also by resistance to contaminant migration within the pore network. The effect of recycling the unreacted contaminants from the bottom of the bed to the top has been examined through simulation, showing that biodegradation takes place mainly in the upper part of the bed.