Soil and Groundwater Contamination Survey and Countermeasure Technologies

Category of Tchnology	Treatment	Treatment
Media	Soil
Contaminants	Volatile Chlorinated Organic Compounds (TCE, PCE, etc) Volatile Hydrocarbon (Benzene, etc)
	Applied (Demonstrated) Substances	Tetrachloroethylene
Scope	Concentration Range
	Hydrogeological Conditions	-	-
	Chemical Soil Properties
	Other Remarks
Technology Description	Classification	Decomposition
	Status	Under Demonstration
	Outline of Technology	The contaminated soil is heated at below 500°C within an indirect heating multi-cylinder rotary kiln, to vaporize the volatile matters and collect them.  The waste gas is treated by absorption by activated carbon before being discharged to the ambient air.  The waste gas from the heating process can be used as carrier gas.  The treatment capacity is 2 tons/hour or 4 tons/hour.
	Required Pre- and Post-treatment	Because the contaminated soil is heated indirectly by getting in touch with the retort pipes, the pre-treatment required before the soil enters the kiln includes the removal of wood chips, stones, etc., crushing of earth blocks and clays, and the removal of water contents if the soil is wet with groundwater.
	Enhance Effectiveness through Combination	If high concentrations of contaminants exist in their original liquid form, vacuum extraction of such matters as a prior on-site treatment will be a good choice.
	Case History	When the contaminated soil containing up to 1000 mg/kg of tetrachloroethylene was heated at low-temperature, the removal rate of the tetrachloroethylene was 99.1% at 135°C, 99.9% at 185°C  and 99.99% at 235°C.  In this test, the sensor tube did not detect tetrachloroethylene in the waste gas which was treated by active carbon.  No analysis was made of other poisonous matters.
	Application Examples	This method has been put to use at several locations, using the system with the processing capacity of 2 tons/hour.
	Limitations
	Properties of Treated Soil	Properties are Generally Retained * Properties may change depending on the heating conditions.
Schematic Flow Process	Flow Chart of the Low-temperature Heating Devices and After-treatment
Applicability	In Situ Applicability	Possible
	Ground Structures	-
	Required Excavation	Excavated soil is treated. (To be applied to excavated soil.)
	Groundwater Extraction
	Required Space	Space for the installation of a set of devices (For example, 4 m  x 3 m)
	Operational Time
	Installation Time
	Maintenance and Control Requirements
	Additional Remarks
Secondary Impacts to Environment	Secondary Treatment Required?	Effluent Water Treatment    Off-gas Treatment
	Effects on Living Environment	Noise
	Additives	Air Others (Fuel)
	Possibility of Contaminant Spreading	Contaminants may disperse in the pre-treatment.
	Secondary By-products	A higher heating temperature will be needed to improve the contaminant removal rate of the soil.  In this case, however, toxic substances may form in the heating process.

• 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