|
KMID : 1156220100360040323
|
|
Journal of Environmental Health Sciences
2010 Volume.36 No. 4 p.323 ~ p.336
|
|
|
Dechlorination of High Concentrations of Tetrachloroethylene Using a Fixed-bed Reactor
|
|
Chang Young-Cheol
Park Chan-Koo
Jung Kweon
Kikuchi Shintaro
|
|
|
Abstract
|
|
|
|
We evaluated the properties of a fixed-bed column reactor for high-concentration tetrachloroethylene (PCE) removal. The anaerobic bacterium Clostridium bifermentans DPH-1 was able to dechlorinate PCE to cis-1,2- dichloroethylene (cDCE) via trichloroethylene (TCE) at high rates in the monoculture biofilm of an upflow fixed-bed column reactor. The first-order reaction rate of C. bifermentans DPH-1 was relatively high at 0.006 mg protein?1 · l · h?1, and comparable to rates obtained by others. When we gradually raised the influent PCE concentration from 30 μM to 905 μM, the degree of PCE dechlorination rose to over 99% during the operation period of 2,000 h. In order to maintain efficiency of transformation of PCE in this reactor system, more than 6 h hydraulic retention time (HRT) is required. The maximum volumetric dechlorination rate of PCE was determined to be 1,100 μmol · d?1l of reactor volume?1, which is relatively high compared to rates reported previously. The results of this study indicate that the PCE removal performance of this fixed-bed reactor immobilized mono-culture is comparable to that of a fixed-bed reactor mixture culture system. Furthermore, our system has the major advantage of a rapid (5 days) start-up time for the reactor. The flow characteristics of this reactor are intermediate between those of the plug-flow and complete-mix systems. Biotransformation of PCE into innocuous compounds is desirable; however, unfortunately cDCE, which is itself toxic, was the main product of PCE dechlorination in this reactor system. In order to establish a system for complete detoxification of PCE, co-immobilization of C. bifermentans DPH-1 with other bacteria that degrade cDCE aerobically or anaerobically to ethene or ethane may be effective.
|
|
|
KEYWORD
|
|
|
Clostridium bifermentans DPH-1, dechlorination, tetrachloroethylene, monoculture, bioreactor
|
|
|
FullTexts / Linksout information
|
|
|
|
|
|
Listed journal information
|
|
|
|