BTEX, MTBE BIOREMEDIATION: BIONETSTM CONTAINING ISOLITE?, PM1, SOS OR AIR

摘要

BTEX (benzene, toluene, ethylbenzene, xylenes) and MTBE are turning up at many American crossroads. The objective of this controlled study was to determine if biologically active in situ BioNets could bioremediate MTBE and BTEX contaminated groundwater. Seven BioNets, most containing 3 fractures each, were placed in a site on the Flathead Indian Reservation in Montana. The MTBE and BTEX plume from a retail gasoline station was contaminating farmland and threatening Native American owned surface waters. The BioNets contained: 1) sand or Isolite? as a fracture material, which created bioremediation zones by facilitating inoculation, allowing attachment of the bacteria, presenting a zone for addition of oxygen by way of aeration or addition of Solid Oxygen Source (SOS) and enhancing the porosity/permeability of the subsurface; 2) PM1, an aerobic bacteria known to degrade MTBE, which can be monitored with a genetic probe; 3) nutrients; and 4) oxygen as air or SOS. Results indicate that 22 months after inoculation the reductions of BTEX in the groundwater samples were as high as 99.7 percent where optimum conditions existed for biodegradation, which included MTBE degrading PM1 inoculated Isolite with SOS or air. The use of SOS stimulates more or as much reduction as the use of oxygen as supplied air at various flow rates. Results also indicate that 12 months after inoculation the reductions of MTBE in the groundwater samples were as high as 85 percent where optimum conditions existed for biodegradation, which included PM1 inoculated Isolite with SOS or air. The use of SOS stimulates more or as much reduction as the use of oxygen as supplied air at various flow rates. After 12 months, DNA of PM1 was isolated from soils from the inoculated BioNets, but not the un-inoculated BioNet. PM1 and naturally occurring MTBE degraders were consistently identified on subsurface soil samples using Taqman geneprobe and standard microbial techniques.