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Development of Sulfidogenic Sludge from Marine Sediments and Trichloroethylene Reduction in an Upflow Anaerobic Sludge Blanket Reactor
Published on: October 15, 2015
Self-inhibition can limit biologically enhanced TCE dissolution from a TCE DNAPL
P J Haest1, D Springael, P Seuntjens
1Division Soil and Water Management, Catholic University of Leuven, Kasteelpark Arenberg 20, B-3001 Leuven, Belgium.
Chemosphere
|July 4, 2012
Summary
Biodegradation near trichloroethene (TCE) Dense Non-Aqueous Phase Liquid (DNAPL) sources showed limited enhancement of TCE dissolution. The study found variable DNAPL distribution, not biodegradation, was the primary driver of enhanced dissolution.
Area of Science:
- Environmental Science
- Geochemistry
- Microbiology
Background:
- Dense Non-Aqueous Phase Liquids (DNAPLs) like trichloroethene (TCE) pose significant groundwater contamination challenges.
- Biodegradation can potentially enhance DNAPL dissolution by increasing concentration gradients at the DNAPL-water interface.
Purpose of the Study:
- To quantify the bio-enhanced dissolution of TCE from a DNAPL source under anaerobic conditions.
- To identify factors limiting biodegradation and bio-enhanced dissolution in a controlled experimental setup.
Main Methods:
- Two-dimensional flow-through sand box experiments with TCE DNAPL and TCE-dechlorinating microbial consortia.
- Analysis of effluent for TCE and daughter products to determine mass transfer.
- Reactive transport modeling using previously determined dechlorination rates.
Main Results:
- Biotic boxes showed 3-6 fold higher total chlorinated compound mass in effluent compared to abiotic boxes.
- Bio-enhanced dissolution factors were estimated between 1.3-2.2, suggesting limited enhancement.
- Reactive transport modeling indicated an enhancement factor of 1.01, with limitations due to short residence time and TCE self-inhibition.
Conclusions:
- Variable DNAPL distribution, rather than biodegradation, was the primary cause of observed enhanced dissolution.
- TCE biodegradation in the experimental setup was limited by short residence times and substrate/product inhibition.
- Significant bio-enhanced dissolution (>2) requires reduced TCE self-inhibition or DNAPL in low-permeability zones.
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