Abstract
As the enhanced natural attenuation (E NA) technique of chlorinated aliphatic hydrocarbons (CAHs) in groundwater, a bio-barrier was installed in an aquifer by injecting the hydr ogen release compound through injection wells approximately once a year. Long term monitoring was conducted for 3 years to evaluate the effectiveness of the technology. At down-gradient of the bio-barrier, total molar concentration of CAHs has been declined, a portion of the CAHs had been degraded to ethane. First-order degradation rates of CAHs in groundwater have been significantly accelerated after bio-barrier installation, and CAHs degradation became stable along time. Groundwater quality after the second hydrogen release compound injection showed apparent different features comparing to the data after the first injection, i. e. changes of pH, DO and ORP in groundwater became small, and no apparent reduction of sulfate was observed.
