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EFFECT OF FENTON'S REAGENT ON SUBSURFACE MICROBIOLOGY AND BIODEGRADATION CAPACITY
Citation:
Kastner, J. R., J Santo Domingo, M. Denham, M Molina, AND R. Brigmon. EFFECT OF FENTON'S REAGENT ON SUBSURFACE MICROBIOLOGY AND BIODEGRADATION CAPACITY. Presented at 5th International Symposium on In Situ and On-Site Bioremediation, San Diego, CA, April 19-22, 1999.
Description:
Microcosm studies were conducted to determine the effect of Fenton's reagent on subsurface microbiology and biodegradation capacity in a DNAPL (PCE/TCE) contaminated aquifer previously treated with the reagent. Groundwater pH declined from 5 to 2.4 immediately after the treatment, and subsequently rose to a range of 3.4 - 4.0 after 17 months. Groundwater microbial direct counts were approximately two orders of magnitude lower in the treated zone compared to the control after one year. Limited bacterial growth and TCE degradation were detected in the treated zone (pH 3.37 and TCE 5 mg/L) with CH4 and phenol amendments. In contrast, methane addition to groundwater from the up-gradient control well stimulated considerable bacterial growth (pH 4.9 and TCE 0.7 mg/L), indicated by methane consumption, fluorescent antibody analysis, phospholipid based markers, and rDNA probes. TCE degradation was measured in the control microcosms, but only when phenol was added. These results suggest that high TCE concentrations, as well as the lower groundwater pH in the treated zone (i.e., pH 3.37 vs. 4.9) could have inhibited methanotrophic TCE co-metabolism. Bioremediation at the leading edge of plume may be possible, as long the local soil is able to buffer the groundwater pH (e.g.,4.0-4.5). Alternatively, the Fenton's reagent process could be designed to operate at a higher pH (e.g.,4.0-4.5) to minimize detrimental effects, providing an optimal environment to couple advanced oxidation processes with bioremediation technologies.