Microcosm andInSituField Studies ofEnhanced Biotransformation ofTrichloroethylen e

(c-DCE), and1,2tans-dichloroethylene (t-DCE) was evaluated bothin groundwater-fed microcosms andinsitu ina shallow aquifer. Microcosms amendedwithphenol or toluene were equally effective inremoving c-DCE(>90%o) followed byTCE (60to70%),while themicrocosm fed methane was mosteffective inremoving t-DCE(>90o%). Themicrocosm fedammonia was theleast effective. Noneofthemicrocosms effectively degraded 1,1,1-trichloroethane. AttheMoffett Field groundwater testsite, insitu removal ofc-DCEandTCE coincided withbiostimulation through phenol andoxygen injection and utilization, withc-DCEremoved more rapidly thanTCE.Greater TCEandc-DCEremoval was observed when thephenol concentration was increased. Over90% removal ofc-DCEandTCE was observed inthe2-m biostimulated zone.This compareswith40to50%oremoval ofc-DCEand15to25%removal ofTCEachieved bymethane-grown microorganisms previously evaluated inan adjacent insitu test zone.Theinsitu removal withphenol-grown microorganisms agreesqualitatively withthemicrocosm studies, withtheratesandextents ofremoval ranked asfollows: c-DCE> TCE > t-DCE. Thesestudies demonstrate thepotential forinsitu TCE bioremediation using microorganisms grown on phenol.