Budapest University of Technology and Economics, Department of Applied Biotechnology and Food Science, Environmental Microbiology and Biotechnology Group
- Halogenated aliphatic organic compounds
- trichloroethane
- Halogenated aliphatic organic compounds
- tetrachloroethylene
- Halogenated aliphatic organic compounds
- vinyl chloride
- Halogenated aliphatic organic compounds
- 1,1-dichloroethane
- Benzene and alkyl benzenes (BTEX)
- m-xylene
- Halogenated aliphatic organic compounds
- 1,1,1-trichloroethane
The technology involves the injection of high pressure steam into an aquifer to thermally enhance conditions so that remediation can be completed at an accelerated rate. Once optimum temperatures have been achieved a high vacuum steam ejector system is used to extract vapours and groundwater. All of the recovered vapour and liquors are cooled in a heat exchange condenser prior to treatment through GAC filters.
The innovative combination of a DPVE system with a system of injecting steam enabled the in-situ treatment of a Xylene impacted clay horizon (located between two permeable horizons) situated above the identified groundwater table. The enhanced system facilitated the delivered steam at high pressure and temperature into the gravel horizon underlying the identified Xylene impacted silt/clay and removed the requirement for excavation.
- thermal
- soil heating with vapour
The physical flushing action of injected steam and hot condensates; Increasing temperatures to change contaminant physical/chemical properties to increase mobility e.g reducing viscosity, capillary/interfacial forces and contaminant density, increasing volatility and desorption rates; Increasing temperatures to affect a change in contaminant partitioning equilibriums, so that a greater proportion of contaminants exist within the dissolved /vapour phases.
Optimising subsurface temperatures for biodegradation.
A vákuum okozta nyomáscsökkenés és csökkenő koncentrációgradiens a talajgáz/gőz talajból kifelé áramlását nagyban meggyorsítja a spontán diffúzióhoz képes. A másik fontos jellemzője, hogy a gőzformájú szennyezőanyag kontroll alá kerül, a kiszívott talajgázzal együtt.
Key risks, in relation to health and safety of personnel, focus on the use of pressurised steam. All staff were appropriately trained and operated to robust, comprehensive, health and safety method statements. Staff expertise was essential to the safe operation of the system.
Mobile steam-production unit and recovery system, highly flexible system, depending of the needs of the site and contaminants.
The effect of heating on soil microflora. The workers risk due to high pressure steam.
Heating Phase: steam was injected until target temperatures of 600C-900C were reached in the substrata. Maintenance Phase: upon achievement of optimum temperatures, a dual pump high vacuum extraction system was used to extract vapours and groundwater. During the maintenance phase steam was periodically injected to maintain temperatures. Air sparging was also undertaken, encouraging in-situ hydrous pyrolysis oxidation of contaminants. Oxygen introduced into a heated subsurface acts, as a powerful oxidiser, cost effectively treating contamination. Recovered vapours and liquors were cooled using a heat-exchanging condenser prior to treatment through Granular Activated Carbon (GAC) filters. Cooling/Polishing Phase: Post heating, subsurface temperatures remain elevated (25 0C and 50 0C). Oxygen essential for biodegradation was introduced by sparging air into the saturated zone and through drawing air into the unsaturated zone under vacuum.
