Thermal blanket for in-situ remediation of surficial contamination: A pilot test

E. T. Iben, W. A. Edelstein, R. B. Sheldon, A. P. Shapiro, E. E. Uzgiris, C. R. Scatena, S. R. Blaha, W. B. Silverstein, G. R. Brown, G. L. Stegemeier, H. J. Vinegar

Research output: Contribution to journalArticlepeer-review

32 Scopus citations


Surficial PCB contamination has been successfully and safely removed from soils in a field test at the site of a former dragstrip where oil- containing PCBs had been sprayed to minimize airborne dust. Decontamination was achieved by electrically heating a 9.3-m 2 area under a thermal blanket, and PCB concentrations were reduced from up to 2000 ppm to less than 2 ppm in 24 h of heating. Initial PCB concentration in some of the more contaminated areas averaged 700 mg/kg from 0 to 7.5 cm deep and 100 mg/kg from 7.5 to 15 cm, with maximum concentrations as high as 2000 mg/kg at the surface. The thermal blanket was operated at temperatures ranging from 815 to 925 °C. It took about 20-24 h for a 15-cm depth to reach 200 °C, which was sufficient to reduce the total PCB concentration to below the mandated 2 mg/kg cleanup levels. The variation of times to reach the desired temperature is principally related to soil water content. A vapor stream was drawn by vacuum from the thermal blanket at a rate of 550-1100 L(STP)/min. Vaporized groundwater constitutes from 40% to 70% of the vapor stream at the beginning of each heating cycle and therefore displaces a significant fraction of the air, but enough remains for oxidation of waste stream hydrocarbons in an external thermal oxidizer. We also tested 2.4 m x 6 m thermal blanket modules that could be assembled into large arrays to treat extensive areas. A full- scale thermal blanket system designed to treat this site would consist of 20 modules assembled into 288 m 2 thermal treatment systems, which require 1.8 MW of power and operate on a three-part cycle: heat and treat soil cool, and move to a new treatment area. Emissions from the blanket consist of organics, which are destroyed by passing through a flameless thermal oxidizer.

Original languageEnglish
Pages (from-to)3144-3154
Number of pages11
JournalEnvironmental Science and Technology
Issue number11
StatePublished - 14 Dec 1996
Externally publishedYes

ASJC Scopus subject areas

  • General Chemistry
  • Environmental Chemistry


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