Jp. Arcangeli et al., BIODEGRADATION OF CIS-1,2-DICHLORO-ETHYLENE AT LOW CONCENTRATIONS WITH METHANE-OXIDIZING BACTERIA IN A BIOFILM REACTOR, Water research, 30(8), 1996, pp. 1885-1893
This work focuses on the kinetics of cis-1,2-dichloro-ethylene (c-DCE)
biodegradation at very low concentrations (mu g/l range) in an aerobi
c fixed-film reactor inoculated with a mixed culture of methane-oxidiz
ing bacteria. Analysis of dissolved components (oxygen, methane, c-DCE
) were performed by membrane-inlet mass-spectrometry allowing an on-li
ne control of the reactor performance. The c-DCE degradation rate cons
tant k(x)/K-s ranged from 0.1 to 5.5 x 10(-2)m(3)d(-1)g(x)(-1), depend
ing on the c-DCE concentration. However, this degradation rate was und
erestimated because the amount of active biomass in the biofilm was sm
all (15% to 20% of the total biofilm dry weight). Toxicity effects wer
e observed when the c-DCE initial concentration was above 100 mu g/l,
leading to a decrease of the c-DCE and methane removal rate. Analysis
showed the formation of an intermediate compound subsequent to the c-D
CE degradation. Preliminary analysis suggested that it was c-DCE-epoxi
de. This degradation product or its metabolites seem to be the cause o
f the deactivation of the cells. However, the toxic effect could be co
unterbalanced, and the c-DCE degradation rate could be partly sustaine
d if methane was supplied continuously in the reactor so that inactiva
ted cells were replaced. These results are of practical interest for g
roundwater restoration or for waterworks since concentrations generall
y encountered in contaminated aquifers are in the mu g/l range. Copyri
ght (C) 1996 Elsevier Science Ltd