EFFECT OF GASEOUS NITROGEN AND PHOSPHORUS INJECTION ON IN-SITU BIOREMEDIATION OF A TRICHLOROETHYLENE-CONTAMINATED SITE

Methane and air were injected through a horizontal well into a trichloroethylene-contaminated site at a depth of 160ft below ground surface to stimulate methanotrophic biodegradation of trichloroethylene (TCE). Sediment samples were analyzed after 35 weeks of methane and air injection, and after 13 weeks of methane and air injection supplemented with injection of the gases nitrous oxide and triethyl phosphate. Methanotroph most-probable-number (MPN) values were very low in most of the samples prior to the addition of nitrogen and phosphorus to the site, and increased several orders of magnitude following the addition, Similarly, the frequency of TCE biodegradative potential in methanotrophic enrichments increased approximately three orders of magnitude after the addition of nitrogen and phosphorus to the site. The MPN and biodegradative potential data indicated that the zone of influence after the addition of nitrogen and phosphorus extended to at least 60 ft from the injection well in both the vertical and horizontal directions.