1 New, Improved Groundwater Cleanup Technology B Y B A R R Y N. N A F T n late 1987. a monitoring program at Lockheed Aeronautical Systems Companv identified solvent
We are able to draw upon Dow's more than 50 years of environmental technology development and experience in the management of hazardous materials. Dow spent $1.2 billion in 1991 on research and development, much of it related to environmental technologies. AWD's technology transfer relationship with Dow allowed us to offer Lockheed a way to comply with the site cleanup order. Within seven months, AWD permitted, pilottested, designed, and installed a prototypical AquaDetox/VES (vapor extraction system) for soil and groundwater treatment. The closedloop facility is a combination of AWD and Dow technologies. The system is composed of a moderate vacuum steam stripper, developed by Dow, and our VES. The patented combination, known as AquaDetox/VES, is a zero air discharge system capable of stripping more than 90 of the 110 volatile organic compounds (VOCs) EPA has identified, including volatiles, acids, baselneutrals, and pesticides.
How it works Contaminated groundwater is fed from a 260-foot-deep extraction well to a heat exchanger where it is heated by the outgoing treated water. From this heat exchanger, the water is pumped to a 60-foot stripping tower, where it flows down through packing material that increases its exposed surface area. Under vacuum pressure, the injection of steam at the tower bottom strips contaminants from the liquid into the vapor stream. The vapor stream is condensed, and the water and PCEITCE phases are separated. The PCE/TCE phase is pumped to a storage tank for collection and recycling. The water phase is recycled to the stripping tower. By the time the water reaches the bottom of the stripping tower, its 0013-936w92/0926-871$03.00/00 1992 American Chemical Society
Environ. Sci. Technol.. Vol. 26, No. 5, 1992 871
Superfund Innovative Technology Evaluation (SITE) of the AquaDetoxNES system
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This technology can treat groundwater and soil-gas contaminated with volatile organic compounds
continuous operation witho steam regeneration. * This system proved highly effe tive in removing VOCs such (rVOCs)., , , he efficiencies ranged from TCE and PCE from groundwatc 99.92% to 99.99% for removal of The system should also be effe VOCs from contaminated groundtive for less volatile organics. water. VOC removal efficiencies The system's steam consumptii for soil-gas ran ed from 98.0% to dropped with decreasing tow 99.9% when t e ranular actipressure. During the demonstr vated carbon (GA8) beds were tion, the system proved more ef re enerated according to the cient at lower operating tow A8D-specified frequency. pressures. This technolog produced effluent * The system has been operatii groundwater tKat complied with successfully for more than tv regulatory discharge requireyears at the Lockheed site. Di ments for TCE and PCE at the ing this time period, the syste Lockheed site throughout the has been in operation 93% of tl SITE demonstration. time, with seven percent dov The GAC beds effectively retime due to scheduled and no moved VOCs from contaminated scheduled repairs. wit-gas even after 34 hours of I
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Cholinestemes Structure, Function, Mechanism,
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Genetics, and Cell Biology resenting the proceedings of the Third International Meeting on Cholinesterases. this inaugural volume in the Conference Proceedings Series offers a wealth of new information on current and future cholinesterase research. including important advances resuiting from new concepts and methodologies such as monoclonal antibodies and molecular genetics. The volume's 49 full DaDers and 140 Doster papers are divided into'sii sections covering:
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Polymorphism and Structure of Cholinesterases Cellular Biology of Cholinesterases Gene Structure and Expression of Cholinesterases Catalytic Mshanirm of Cholinesterases: Structurehnction Relationshipsof Antkholinerterare Agents. Nerve Agents. and Pertirider Pharmatologiral Utilization of Anticholinesterase Agents. Neuropathology of Cholinergic Systems e Nontholineigic Roles of Cholinerterares 0 0 0
This volume will be of great interest to a broad spectrum of readers. including those interested in the evolution of cholinesterase catalysis, researchers developing agricultural chemicals.scientists seeking up-to-date information on the treatment of glaucoma and such neurological diseases as Alzheimer's disease and myasthenia gravis.those interested in the design of drugs to bind the enzyme itself or to cholinergic receptors. as weli as those who foliow the progress toward complete structure elucidation of cholinesterases. Jean Massoulie. Centre National de la Recherche Scientifique. Editor Francis Bacou. lnstitut National de la Recherche Agronornique. Editor Eric Barnard. Medical Research Council. Editor Arnaud Chatonnet. lnstitut National del la Recherche Agronornique. Editor Bhupendra P. Doctor. Walter Reed Army Institute of Research. Editor Daniel M. Quinn. University of Iowa. Editor Conference Proceedinas Series 414 pages (1991)Clo
