Soil and Groundwater Contamination Survey and Countermeasure Technologies

Category of Tchnology	Treatment	Treatment
Media	Groundwater
Contaminants	Volatile Chlorinated Organic Compounds (TCE, PCE, etc)
	Applied (Demonstrated) Substances	Trichloroethylene
Scope	Concentration Range	A test made by adding pure water proved that the system effectively treated the concentrations of up to 10 mg/l.
	Hydrogeological Conditions	-	-
	Chemical Soil Properties
	Other Remarks
Technology Description	Classification	Decomposition
	Status	Under Demonstration Soil and Groundwater Countermeasure Test Study (Performed 1994)
	Outline of Technology	The contaminated groundwater, after being pumped out and added hydrogen peroxide, is exposed to the ultraviolet ray generated by low-voltage mercury lamps so that the OH free radical formed due to the decomposition of hydrogen peroxide decomposes trichloroethylene, etc. After the decomposition, the water is passed through the layer of active carbon to decompose the residue hydrogen peroxide, and then subjected to pH adjustment by using alkali.  Unlike the aeration process, this method does not require the treatment of the waste gas.
	Required Pre- and Post-treatment
	Enhance Effectiveness through Combination
	Case History	The decomposition reduced the concentrations of trichloroethylene from more than 1 mg/l to less than 0.005 mg/l, with the concentrations of hydrogen peroxide kept at 20 mg/l and the irradiation volume of ultraviolet ray at 1.0 kwh/m3, or the concentrations of hydrogen peroxide at 60 mg/l and the irradiation volume of ultraviolet ray at not less than 0.4 kwh/m3.
	Application Examples	Besides the demonstrative test made by the Environment Agency, other such tests are being made at various sites contaminated with trichloroethylene, etc.
	Limitations	The processing efficiency decreases if the groundwater contains the substance inhibiting the decomposition by oxidization, such as reductants. If the groundwater contains high concentrations of saturated compounds, such as dichloroethane and trichloroethane, which are hard to decompose, this process should be used in combination with other treatment processes.  Without such combination, it will be difficult to apply this method to the water containing chloromethanes.
	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?
	Effects on Living Environment
	Additives	Oxidants/ Reductants (H2O2) Others (Ultraviolet radiation)
	Possibility of Contaminant Spreading	None
	Secondary By-products	The water is discharged after pH adjustment because hydrogen chloride forms as a result of the decomposition.

• 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