Recovery of Phenanthrene-Degrading Bacteria after Simulated in Situ Persulfate Oxidation in Contaminated Soil

Abstract

A continuous-flow column study was conducted to investigate the long-term effects of persulfate oxidation on the abundance and activity of the indigenous microbial community and phenanthrene-degrading bacteria in contaminated soil from a former manufactured gas plant (MGP) site. Approximately six pore volumes of a 20 g/L persulfate solution were introduced into the column, followed by simulated groundwater for 500 d. Soil samples were collected from the surface of the soil bed and along the column length immediately before and after persulfate injection and up to 500 d following injection. Exposure to persulfate led to a two-to three-log reduction in total bacterial 16S rRNA genes, severe inhibition of 14 C-acetate mineralization (as a measure of general microbial activity), and a decrease in community diversity. However, relatively rapid recovery of both bacterial gene abundance and activity was observed within 30 d after persulfate exposure. Mineralization of 14 C-phenanthrene was also inhibited but did not recover until 100 d post-oxidation. Known phenanthrene-degrading bacterial groups decreased to below detection limits throughout the column, with recovery times from 100 d to 500 d after persulfate injection. These findings suggest that coupling biological processes with persulfate oxidation is possible, although recovery of specific contaminant degraders may occur much later than the general microbial community recovers. Furthermore, the use of total bacterial quantity or non-specific measures of activity as a surrogate for the recovery of contaminant degraders may be inappropriate for evaluating the compatibility of chemical treatment with subsequent bioremediation.

Identification of Anthraquinone-Degrading Bacteria in Soil Contaminated with Polycyclic Aromatic Hydrocarbons

“…Extracts containing anthracene were analyzed by HPLC with fluorescence detection as described elsewhere (35). Extracts containing anthraquinone were analyzed by HPLC on the same system but with UV detection (Applied Biosystems [Ramsey, NJ] Kratos Analytical Spectroflow 757 UV absorbance detector).…”

Combining in situ chemical oxidation, stabilization, and anaerobic bioremediation in a single application to reduce contaminant mass and leachability in soil

“…Tsitonaki [28] showed that aerobic biodegradation of creosote compounds in soil columns recovered within 2 weeks after heat activation of persulfate concentrations as high as 30 g/L. [23] passed 6 pore volumes of a 20 g/L persulfate solution through soil columns, maintained at 40 • C for activation. This caused a 2-to 3-log reduction in total bacterial 16S rRNA and a decrease in acetate consumption.…”

Biostimulation Reveals Functional Redundancy of Anthracene-Degrading Bacteria in Polycyclic Aromatic Hydrocarbon-Contaminated Soil

“…Soil properties and details of samples can be found in Richardson, et al (2011). The concentration of solvent-extractable anthracene in untreated and bioreactor-treated soil was 15 and 2 mg/kg, respectively .…”