Anaerobic BTEX degradation in soil bioaugmented with mixed consortiaunder nitrate reducing conditions
DOU Junfeng , LIU Xiang , HU Zhifeng
DOI:
Received July 29, 2007,Revised November 21, 2007, Accepted , Available online
Volume 20,2008,Pages 585-592
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Different concentrations of BTEX, including benzene, toluene, ethylbenzene, and three xylene isomers, were added into soil samples
to investigate the anaerobic degradation potential by the augmented BTEX-adapted consortia under nitrate reducing conditions. All
the BTEX substrates could be anaerobically biodegraded to non-detectable levels within 70 d when the initial concentrations were
below 100 mg/kg in soil. Toluene was degraded faster than any other BTEX compounds, and the high-to-low order of degradation
rates were toluene > ethylbenzene > m-xylene > o-xylene > benzene > p-xylene. Nitrite was accumulated with nitrate reduction,
but the accumulation of nitrite had no inhibitory effect on the degradation of BTEX throughout the whole incubation. Indigenous
bacteria in the soil could enhance the BTEX biodegradation ability of the enriched mixed bacteria. When the six BTEX compounds
were simultaneously present in soil, there was no apparent inhibitory effect on their degradation with lower initial concentrations.
Alternatively, benzene, o-xylene, and p-xylene degradation were inhibited with higher initial concentrations of 300 mg/kg. Higher
BTEX biodegradation rates were observed in soil samples with the addition of sodium acetate compared to the presence of a single
BTEX substrate, and the hypothesis of primary-substrate stimulation or cometabolic enhancement of BTEX biodegradation seems
likely.
