COMPLETE DECHLORINATION OF TETRACHLOROETHYLENE BY USE OF AN ANAEROBIC CLOSTRIDIUM BIFERMENTANS DPH‐1 AND ZERO‐VALENT IRON

Abstract

A laboratory test was conducted to examine the combined effect of an anaerobic Clostridium bifermentans DPH‐1 and addition of zero‐valent iron (Fe⁰) on the reductive dechlorination of tetrachloroethylene (PCE). In addition, the dechlorination of cis‐1,2‐dichloroethylene (cDCE) produced from PCE was examined using Fe⁰. The cDCE produced was completely dechlorinated to non‐toxic end products, mostly, ethylene by a subsequent chemical reductive process. Production of ethylene was dramatically increased with increase of initial cDCE concentration in the range of 10.3 µM to 928 µM (1.0–90 mg l⁻¹) and the velocity constant was calculated to be 0.38 day⁻¹. On the other hand, the combined use of strain DPH‐1 and Fe⁰ showed the most significant effect on the initial PCE dechlorination, but cohesion of Fe⁰ was found to inhibit the dechlorination rate of PCE. It is thought that phosphoric acid iron contained in a medium forms film on the surface of iron particle, so oxidation of iron is inhibited.

Keywords:

• Dechlorination
• tetrachloroethylene (PCE)
• cis‐1,2‐dichloroethylene (cDCE)
• Clostridium bifermentans DPH‐1
• zero‐valent iron

ACKNOWLEDGEMENT

The authors thank to Dr. Okeke B.C. of Auburn University for critical reading of manuscript.