Anaerobic Bioremediation of Groundwater Containing a Mixture of 1,1,2,2-Tetrachloroethane and Chloroethenes |
| |
Authors: | Federico Aulenta Monica Potalivo Mauro Majone Marco Petrangeli Papini Valter Tandoi |
| |
Institution: | (1) Department of Chemistry, University of Rome “La Sapienza”, P.le Aldo Moro 5, 00185 Rome, Italy;(2) Water Research Institute, National Research Council (IRSA-CNR), Via Reno 1, 00198 Rome, Italy |
| |
Abstract: | This study investigated the biotransformation pathways of 1,1,2,2-tetrachloroethane (1,1,2,2-TeCA) in the presence of chloroethenes
(i.e. tetrachloroethene, PCE; trichloroethene, TCE) in anaerobic microcosms constructed with subsurface soil and groundwater
from a contaminated site. When amended with yeast extract, lactate, butyrate, or H2 and acetate, 1,1,2,2-TeCA was initially dechlorinated via both hydrogenolysis to 1,1,2-trichloroethane (1,1,2-TCA) (major
pathway) and dichloroelimination to dichloroethenes (DCEs) (minor pathway), with both reactions occurring under sulfidogenic
conditions. In the presence of only H2, the hydrogenolysis of 1,1,2,2-TeCA to 1,1,2-TCA apparently required the presence of acetate to occur. Once formed, 1,1,2-TCA
was degraded predominantly via dichloroelimination to vinyl chloride (VC). Ultimately, chloroethanes were converted to chloroethenes
(mainly VC and DCEs) which persisted in the microcosms for very long periods along with PCE and TCE originally present in
the groundwater. Hydrogenolysis of chloroethenes occurred only after highly reducing methanogenic conditions were established.
However, substantial conversion to ethene (ETH) was observed only in microcosms amended with yeast extract (200 mg/l), suggesting
that groundwater lacked some nutritional factors which were likely provided to dechlorinating microorganisms by this complex
organic substrate. Bioaugmentation with an H2-utilizing PCE-dechlorinating Dehalococcoides spp. -containing culture resulted in the conversion of 1,1,2,2-TeCA, PCE and TCE to ETH and VC. No chloroethanes accumulated
during degradation suggesting that 1,1,2,2-TeCA was degraded through initial dichloroelimination into DCEs and then typical
hydrogenolysis into ETH and VC. |
| |
Keywords: | bioremediation Dehalococcoides dechlorination microcosm tetrachloroethane trichloroethene |
本文献已被 PubMed SpringerLink 等数据库收录! |
|