Pilot scale testing composite swellable organosilica nanoscale zero-valent iron-Iron-Osorb®-for in situ remediation of trichloroethylene

Iron-Osorb® is a solid composite material of swellable organosilica with embedded nanoscale zero-valent iron that was formulated to extract and dechlorinate solvents in groundwater. The unique feature of the highly porous organosilica is its strong affinity for chlorinated solvents, such as trichloroethylene (TCE), while being impervious to dissolved solids. The swellable matrix is able to release ethane after dechlorination and return to the initial state. Iron-Osorb® was determined to be highly effective in reducing TCE concentrations in bench-scale experiments. The material was tested in a series of three pilot scale tests for in situ remediation of TCE in conjunction with the Ohio Environmental Protection Agency at a site in central Ohio. Results of these tests indicate that TCE levels were reduced for a period of time after injection, then leveled out or bounced back, presumably due to depletion of zero-valent iron. Use of tracer materials and soil corings indicate that Iron-Osorb® traveled distances of at least 20 feet from the injection point during soil augmentation. The material appears to remain in place once the injection fluid is diluted into the surrounding groundwater. Overall, the technology is promising as a remediation method to treat dilute plumes or create diffuse permeable reactive barriers. Keys to future implementation include developing injection mechanisms that optimize soil distribution of the material and making the system long-lasting to allow for continual treatment of contaminants emanating from the soil matrix. © 2011 Wiley Periodicals, Inc.