Monday, March 20, 2006

Lasagna (tm)


Lasagna Soil REmediation

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Innovative Technology Summary
Lasagna (tm)

GNET makes these documents available in the Adobe Portable Data Format (.PDF) which can be read using the Adobe Acrobat Reader.

Summary:

Technology Description

Lasagna is an integrated, in situ remediation technology being developed by an industrial consortium consisting of Monsanto, E. 1. DuPont de Nemours & Co., Inc. (DuPont), and General Electric, with participation from the Department of Energy (DOE) Office of Environmental Management, Office of Science and Technology (EM-50), and the Environmental Protection Agency (EPA) Office of Research and Development (Figure 1).

Lasagna tm remediates soils and soil pore water contaminated with soluble organic compounds. Lasagna TM is especially suited to sites with low permeability soils where electroosmosis can move water faster and more uniformly than hydraulic methods, with very low power consumption. The process uses electrokinetics to move contaminants in soil pore water into treatment zones where the contaminants can be captured or decomposed. Initial focus is on trichloroethylene (TCE), a major contaminant at many DOE and industrial sites. Both vertical and horizontal configurations have been conceptualized, but fieldwork to date is more advanced for the vertical configuration. Major features of the technology are

  • electrodes energized by direct current, which causes water and soluble contaminants to move into or through the treatment layers and also heats the soil;
  • treatment zones containing reagents that decompose the soluble organic contaminants or adsorb contaminants for immobilization or subsequent removal and disposal; and
  • a water management system (not shown), which recycles the water that accumulates at the cathode (high pH) back to the anode (low pH) for acid-base neutralization. Alternatively, electrode polarity can be reversed periodically to reverse electro-osmotic flow and neutralize pH.

Technology Status

A proof-of-concept field demonstration was conducted at the Paducah Gaseous Diffusion Plant in Paducah, Kentucky.

U. S. Department of Energy
Paducah Gaseous Diffusion Plant (PGDP) Cylinder Drop Test Area (SWMU 91 )
Paducah, Kentucky
January 1995 through May 1995

The demonstration was sponsored by the DOE EM-50 Industrial Program through the Morgantown Energy Technology Center.

The PGDP site consists of a 4-ft layer of gravel and clay overlaying a 40-ft layer of sandy clay loam with interbedded sand layers. The clay soil had been contaminated with TCE at concentrations ranging from 1 ppb to 1760 ppm. Because of its very low organic content, the soil adsorbed very little TCE. The zone to be remediated measured 15-ft wide by 10-ft across and 15-ft deep, with average contamination of 83.2 ppm. The highest TCE concentrations (200-300 ppm) were found 12-16 ft below the surface. Steel panels were used as electrodes and the treatment zones consisted of wick drains containing granular activated carbon to adsorb the TCE. A plastic-wrapped shed was built above the test area, and a vent fan directed soil off-gas to an in-line filter for TCE capture.

Two patents covering the technology have been granted to Monsanto, and the term Lasagnatm has also been trademarked by Monsanto. Developing the technology so that it can be used with assurance for site remediation is the overall objective of the sponsoring consortium.

Key Results

  • Soil samples taken throughout the test site before and after the test indicated an average removal efficiency of 98% for TCE, with some samples showing greater than 99% removal. TCE soil levels were reduced to an average concentration of 1.2 ppm.
  • Flow rate by electroosmosis was 4 L/h, and three pore volumes of water (between adjacent treatment zones) were transported during the 4-month operating period.
  • Dense, non-aqueous-phase liquid (DNAPL) locations were cleaned to 1 -ppm levels except for a 15-ft deep sample that was reduced to 17.4 ppm (Note that because treatment zones were only 15-ft deep, diffusion from untreated deep zones may have contributed to the 17.4-ppm result.)
  • A TCE mass balance at test conclusion accounted for about 50% of TCE. Differences may be a result of passive diffusion (5%), evaporation (5%), in situ degradation of TCE during the test, or incomplete extraction of TCE from the activated carbon prior to analysis. About 20% (12 of 64) of the wicks were sampled. Given the highly nonuniform TCE concentrations in the soil and the limited sampling, a mass balance of 50% is an excellent result.
  • Based on the initial field tests, treatment costs for a typical 1-2-acre site with contamination to a depth of 40-50 ft were estimated to be about $50-$90/yd 3 of treated soil.

Phase II

A commercial-scale development demonstration (Phase Ila) is planned for the Paducah site in 1996, using iron filings in the treatment zones to dechlorinate the TCE in situ. The goal is to reduce soil contamination to 5.6 ppm or less in the 20 ft x 30 ft x 45-ft deep treatment zone. If successful, this will be followed by a full-scale first application demonstration (Phase II) encompassing the entire contaminated region (105 ft x 60 ft x 45-ft deep), with treatment accomplished in 12 to 24 months.

Contacts

Technical

Sa V. Ho, Principal Investigator, Monsanto, (314) 694-5179
Steven C. Meyer, Project Manager, Phase 11A, Monsanto Enviro-Chem, (314) 275-5946
Joseph J. Salvo, General Electric, (518) 387-6123
Stephen H. Shoemaker, DuPont, (713) 586-2513

Management

Skip Chamberlain, DOE EM-50 Program Manager, (301 ) 903-7248
Jim Wright, DOE Plume Focus Area Manager, (803) 725-5608
Kelly Pearce, DOE Contract Representative, (304) 285-5424

Paducah Site Support

Myrna Redfield, DOE EM-40 Program Manager, (502) 441-6815
Fraser Johnstone, Lockheed Martin Energy Systems Project Manager, (502) 441-5077
Jay Clausen, Lockheed Martin Energy Systems Technical Manager, (502) 441-5070

posted by Lá Xanh @ 4:03 AM