DESIGN AND OPERATION OF THE REMEDIATION TECHNOLOGY DEVELOPMENT FORUM IN SITU BIOAUGMENTATION PILOT SYSTEM FOR ACCELERATED BIOREMEDIATION

摘要

A 12- by 18-meter hydraulically controlled pilot system was designed, constructed,and operated at Dover Air Force Base located in Dover, Delaware. The system wasdesigned to convey amendments 15 meters below ground surface in an alluvialaquifer. Initial trichloroethene (TCE) and 1,2-dichloroethene (DCE) concentrations ingroundwater averaged 4,800 and 1,200 micrograms (礸)/liter (L). The pilot operatedfor 577 days. Operational results by day 274 confirmed previous laboratory workshowing that dechlorination did not proceed past DCE. By this time, most of the TCEwas dechlorinated to DCE, and DCE was the predominant contaminant. Vinyl chlorideand ethene were not observed.Subsequent to laboratory column studies, a suspended mixed culture from theDepartment of Energy抯 (DOE抯) Pinellas site in Largo, Florida, was identified ashaving dehalogenating capability and scaled up. Bioaugmentation with the Pinellasculture was conducted twice. Two 180-L batches were injected in the subsurface.After a lag period of approximately 90 days, vinyl chloride and ethene appeared inwells. By day 518, all of the chlorinated solvents were biodegraded to ethene. Massbalance calculations indicate near stoichiometric conversion of TCE and DCE toethene occurred.Significant operation and maintenance key learnings were derived from this project,including substrate pulsed injection, well plugging and maintenance, and monitoringprotocols.