Soil and Groundwater Contamination Survey and Countermeasure Technologies

Category of Tchnology	Treatment	Treatment
Media	Soil Gas, Others (Off-gas from the stripper)
Contaminants	Volatile Chlorinated Organic Compounds (TCE, PCE, etc)
	Applied (Demonstrated) Substances	Trichloroethylene
Scope	Concentration Range	Gas containing up to 1000 ppmv of trichloroethylene was successfully treated in a test.
	Hydrogeological Conditions	-	-
	Chemical Soil Properties
	Other Remarks
Technology Description	Classification	Decomposition
	Status	Under Demonstration
	Outline of Technology	The gas extracted from underground soil, or treated by aeration, is passed through a filter and led to a 2-stage reaction tank, where it is exposed to the radiation of ultraviolet ray to decompose trichloroethylene, etc., in the air.  The waste gas is passed through the absorption tower, filled with marbles wet by water, which absorbs the compounds formed as a result of the decomposition.
	Required Pre- and Post-treatment	This is to treat the gas extracted from underground soil, or the waste gas after being treated by aeration.   It is necessary to treat the waste water from the absorption tower because the organic matters formed are absorbed in the tower (activated sludge method).
	Enhance Effectiveness through Combination
	Case History	The decomposition rate was higher than 96% in a test in which the gas containing 1500 ppmv of trichloroethylene was treated at a speed of 0.4m3 per minute.  Although the rate decreased when the concentrations at the entrance fell, or gas flow increased, the concentrations of trichloroethylene were low at below 1 ppmv at the exit of the second stage reaction tank.  Organic matters formed as a result of the decomposition were removed without problem, by being absorbed by marbles at the space velocity of 450hr-1.
	Application Examples
	Limitations
	Properties of Treated Soil	-
Schematic Flow Process
Applicability	In Situ Applicability	Possible
	Ground Structures	-
	Required Excavation
	Groundwater Extraction
	Required Space
	Operational Time
	Installation Time
	Maintenance and Control Requirements
	Additional Remarks
Secondary Impacts to Environment	Secondary Treatment Required?	Effluent Water Treatment
	Effects on Living Environment	Noise
	Additives	Water Others (Ultraviolet rays)
	Possibility of Contaminant Spreading	None
	Secondary By-products	VOCs form as a result of the decomposition, but they are removed by being processed with marbles.  It has been confirmed that this process is free of mutagenicity.

• 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