Soil and Groundwater Contamination Survey and Countermeasure Technologies

Category of Tchnology	Treatment	Counterplan Technology
Media	Soil
Contaminants	Heavy Metal (Cd, Pb, As, Hg, Se, etc) Inorganic Compounds (total CN, etc) Volatile Chlorinated Organic Compounds (TCE, PCE, etc) Volatile Hydrocarbon (Benzene, etc)
	Applied (Demonstrated) Substances	Mercury
Scope	Concentration Range	Contaminated soil containing 20-1,000 ppm as mercury
	Hydrogeological Conditions	-	-
	Chemical Soil Properties
	Other Remarks
Technology Description	Classification	Separation
	Status	Under Demonstration Soil and Groundwater Countermeasure Test Study (Performed 1995-1996)
	Outline of Technology	The excavated contaminated soil is heated indirectly, and is brought to contact with heated steam (300-800°C), thus letting the contaminants vaporize and remove from the soil to clean the contaminated soil.  The emitted contaminants are treated by a flue gas treatment system containing a bag filter, a condenser, a scrubber, an activated carbon adsorber and a catalytic oxidizing reactor.  The condensate containing the contaminants is treated by a waste water treatment unit.
	Required Pre- and Post-treatment	As the pre-treatment system, granules and stones having sizes of 20mm or more are removed. As for the post-treatment system, the emitted contaminants are treated by a flue gas treatment unit, and the condensate containing the contaminants generated during the flue gas treatment is treated by a waste water treatment unit.
	Enhance Effectiveness through Combination
	Case History	In each stage of bench scale test and of on-site pilot plant demonstration test, contaminated soils containing 20-1,000 ppm of mercury were treated to obtain 98.8-99.999% of mercury removal rate.  Elution test of the treated-soil did not show elution of mercury.  The mercury concentration of the flue gas after the treatment was 15 ug/m3 or less,(15µg/m3 is the limit of WHO).  The concentrate containing mercury was treated by coagulation sedimentation, activated carbon adsorption, and chelate resin adsorption to give mercury concentrations of 0.0005mg/l or less, (0.005mg/l is the limit of environmental regulation).  In the bench scale test, the mass balance of mercury was established.  In the pilot plant test, however, about 50% of the mercury was lost unidentified in the mass balance.
	Application Examples	Dealing with mercury-contaminated soils sampled from chemical plant areas, a pilot plant having a capacity of 100kg/h conducted cleaning demonstration tests.
	Limitations	There needs a heat source such as city gas to supply heated steam.
	Properties of Treated Soil	Possibility of Change in Properties
Schematic Flow Process
Applicability	In Situ Applicability	Possible
	Ground Structures
	Required Excavation	Excavated soil is treated (To be applied to excavated soil)
	Groundwater Extraction
	Required Space	Area of about eight trailer trucks is required for the on-site pilot plant test.
	Operational Time
	Installation Time
	Maintenance and Control Requirements
	Additional Remarks	A heat source to supply heated steam is required.
Secondary Impacts to Environment	Secondary Treatment Required?	Effluent Water Treatment    Off-gas Treatment
	Effects on Living Environment	Noise Vibration
	Additives	Others (steam)
	Possibility of Contaminant Spreading	None
	Secondary By-products	Regarding the ingredients existing in the contaminated soil, there is a need to check the possibility of non-intentional generation of toxic substances.

• Understanding the Contamination Survey and Countermeasure Technology Description Sheet
• Where to make contact

Soil Environment Management Division, Water Environment Department, Environmental Management Bureau, Ministry of Environment
Tel: +81-3-5521-8319
E-mail: MOE@env.go.jp