title: Biocontainment of polychlorinated biphenyls (PCBs) on flat concrete surfaces by microbial carbonate precipitation.
abstract: In this study, a biosealant obtained from microbial carbonate precipitation (MCP) was evaluated as an alternative to an epoxy-coating system. A bacterium Sporosarcina pasteurii strain ATCC 11859, which metabolizes urea and precipitates calcite in a calcium-rich environment, was used in this study to generate the biosealant on a PCB-contaminated concrete surface. Concrete cylinders measuring 3 in (76.2 mm) by 6 in (152.4 mm) were made in accordance with ASTM C33 and C192 and used for this purpose. The PCB, urea, Ca(2+), and bacterial cell concentrations were set at 10 ppm, 666 mM, 250 mM, and about 2.1 × 10(8) cells mL(-1), respectively. The results indicate that the biosealed surfaces reduced water permeability by 1-5 orders of magnitude, and had a high resistance to carbonation. Since the MCP biosealant is thermally stable under temperatures of up to 840 °C, the high temperatures that normally exist in the surrounding equipment, which may contain PCB-based fluids, have no effect on the biosealed surfaces. Consequently, there is greater potential to obtain a stronger, coherent, and durable surface by MCP. No measurable amount of PCBs was detected in the permeating water, indicating that the leaching water, if any, will have a minimum impact on the surrounding environment.
authors.affiliation: Department of Civil Engineering and Mechanics, University of Wisconsin-Milwaukee, Milwaukee, WI 53201, USA. gokwadha@uwm.edu
authors.forename: George D O
authors.initials: GD
authors.lastname: Okwadha
authors.forename: Jin
authors.initials: J
authors.lastname: Li
mesh_terms: D002119:Calcium Carbonate / Q000378:metabolism*; D003247:Conservation of Natural Resources / Q000379:methods*; D003252:Construction Materials / Q000382:microbiology*; D010539:Permeability; D011078:Polychlorinated Biphenyls; D012989:Soil Pollutants; D058644:Sporosarcina / Q000378:metabolism*; D013499:Surface Properties; D013696:Temperature; D014867:Water
chemical_list: D012989:Soil Pollutants; D014867:Water; D011078:Polychlorinated Biphenyls; D002119:Calcium Carbonate