TRANSFORMATION OF TETRACHLOROETHENE IN AN UPFLOW ANAEROBIC SLUDGEBLANKET REACTOR

Reductive dechlorination of tetrachloroethene was studied in a mesophi lic upflow anaerobic sludge blanket reactor. Operating the reactor in batch mode the dynamic transformation of tetrachloroethene, trichloroe thene and dichloroethene (DCE) was monitored. Tetrachloroethene was re ductively dechlorinated to trichloroethene, which again was dechlorina ted at the same rate as DCE was produced. DCE showed a lag period of 4 0 h before transformation was observed. During normal reactor operatio n trans-1,2-DCE was the major DCE isomer, followed by cis-1,2-DCE. Sma ll amounts of 1,1-DCE but no vinyl chloride were detected. When the in fluent tetrachloroethene concentration was increased from 4.6 mu M to 27 mu M, the transformation rate increased, indicating that the system was not saturated with tetrachloroethene. The main organic component in the effluent was acetate, indicating that the aceticlastic methane- producing bacteria were inhibited by the chlorinated ethenes.