Soil and Groundwater Contamination Survey and Countermeasure Technologies

Category of Tchnology	Treatment	On-site Decomposition/Treatment Technologies
Media	Soil, Groundwater
Contaminants	Volatile Chlorinated Organic Compounds (TCE, PCE, etc) Semi Volatile Chlorinated Organic Compounds (PCB, etc) Volatile Hydrocarbon (Benzene, etc)
	Applied (Demonstrated) Substances	Trichloroethylene
Scope	Concentration Range	Trichloroethylene below 10 mg/l
	Hydrogeological Conditions	Saturated Unsaturated	Permeable Layer
	Chemical Soil Properties	pH4-10
	Other Remarks	High permeability is essential.
Technology Description	Classification
	Status	Under Demonstration Soil and Groundwater Countermeasure Test Study (Performed 1993-1994)
	Outline of Technology	Microbial functions to decompose chemicals are used to decompose and degrade contaminants released to the environment.  Air, methane, nitrogen, and phosphorus are injected into the soil contaminated with trichloroethylene to promote the breeding of methane-acidified microbes, thereby to remove trichloroethylene on-site.
	Required Pre- and Post-treatment	Groundwater extraction and vacuum-extraction technologies shall also be used if the contamination exceeds 10 mg/l.  This method is particularly effective for the contamination with low trichloroethylene concentration.
	Enhance Effectiveness through Combination
	Case History	A month-long injection of oxygen, methane, nitrogen and phosphorus into the contaminated soil contributed to the breeding of decomposer microbes, which continued to decompose trichloroethylene in concentration of 5 mg/l for about 40 days.
	Application Examples	This has proven effective to clean the groundwater contaminated by trichloroethylene in concentration of about 5 mg/l.
	Limitations	Combination with the groundwater extraction and vacuum-extraction technologies is recommended for highly-concentrated contamination.
	Properties of Treated Soil	Properties are Generally Retained
Schematic Flow Process	Typical System of Water Injection/Collection Wells for On-site Bioremediation
Applicability	In Situ Applicability	Possible
	Ground Structures	Applicable even if Ground Structures are Present
	Required Excavation	Necessary to dig wells for injecting/pumping groundwater.
	Groundwater Extraction	Required
	Required Space
	Operational Time	The process needs a long time if liquid contaminants exist and remain unremoved.
	Installation Time
	Maintenance and Control Requirements	Although groundwater injection/pumping and addition of nutritional salt are automated, regular inspections are necessary.
	Additional Remarks
Secondary Impacts to Environment	Secondary Treatment Required?	Effluent Water Treatment
	Effects on Living Environment
	Additives	Nutrient Salts   Air  Water  Others (Methane)
	Possibility of Contaminant Spreading	The injection of groundwater may cause it.
	Secondary By-products	Trichloroethylene may disintegrate and form dichloroacetic acid and trichloroacetic acid, which may remain.

• 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