The interactions among seven creosote-related compounds (phenanthrene, fluorene, p-cresol, pentachlorophenol, carbazole, dibenzothiophene, and dibenzofuran) during their aerobic biodegradation in groundwater were studied in factorial experiments. Three separate experiments were conducted in simple batch systems with phenanthrene, p-cresol, and carbazole as the response variable forthe first, second, and third experiments, respectively, and other compounds as factors. In general, the more hydrophobic and recalcitrant compounds were more affected by substrate interaction. Mineralization of p-cresol was not affected by substrate interaction. In contrast, p-cresol inhibited mineralization of phenanthrene, but other compounds did not. Mineralization of carbazole was severely affected by the presence of other compounds. p-Cresol was the main inhibitor. Phenanthrene inhibited biodegradation, but to a lesser extent, whereas fluorene enhanced mineralization of carbazole. Pentachlorophenol and dibenzofuran caused an increase in the lag time but did not affect mineralization of carbazole afterward.
Extensive characterization of a nitrate‐contaminated site at a Canadian airport revealed that natural attenuation of the plume was limited due to aerobic conditions. However, nitrate removal rates as high as 1.4 mg‐N/(L/day) were observed in batch tests carried out under denitrifying conditions with an added carbon source. On the basis of these results, a field denitrification pilot test using a setup of vertical withdrawal and injection wells was carried out. Ethanol was used as a carbon source to stimulate the growth and activity of indigenous denitrifying bacterial populations. Denitrification rates of up to 1.2 mg‐N/(L/day) were achieved during the test. The test confirmed the feasibility of the technology, which uses the indigenous bacterial populations for denitrification and transforms the aquifer into a subsurface bioreactor.
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