Simulation of reductive dechlorination processes in a lab-scale anaerobic biobarrier with enriched TCP dechlorinating consortium

Abstract

In order to design and predict the dechlorination processes for remediating the halogenated aromatic compounds in the biobarrier system applied in situ, an anaerobic continuous-flow column was set up with the introduction of an enriched 2, 4, 6-trichlorophenol (TCP) reductive dechlorinating consortium. The fates of TCP and its metabolites were simulated according to the first-order sequential dechlorination kinetic model. The enriched TCP anaerobic dechlorinating consortium dechlorinated 100 μmol/L TCP to 4-chlorophenol (4-CP) via 2,4-dichlorophenol (DCP) in 10 d. The consortium was predominated with the phylum of Firmicutes and Bacteroidetes, based on the PCRdenaturing gradient gel electrophoresis (DGGE) analysis. After the consortium was applied to the column, the experimental data in the steady state were fitted by the least square method, and the first-order dechlorination kinetic constants from TCP to 2,4-DCP, from 2,4-DCP to 4-CP and from 4-CP to phenol, were 1.58 d−1, 2.23 d−1 and 0.206 d−1, respectively. According to the fitting results, the required biobarrier width for the complete remediation of TCP, 2,4-DCP and 4-CP were 126 cm, 130 cm and 689 cm, respectively. The dechlorination/ degradation of 4-CP must be increased when the technology is applied to the real site.