Previous Article | Next Article ![]()
Appl. Environ. Microbiol., Jan 1995, 27-33, Vol 61, No. 1
H Harms and AJB Zehnder
One of the main factors impeding the bioremediation of polluted soils,
sediments, and aquifers is the low bioavailability of chemicals which are
sorbed by organic matter. To obtain more insight into the factors that
control the degradation of sorbed compounds, we used a defined model system
in which 3-chlorodibenzofuran (3CDF) was the organic contaminant, porous
Teflon granules were the sorbent, and Sphingomonas sp. strain HH19k was the
test organism. The sorption of 3CDF to Teflon reached equilibrium within
150 min. The curved shape of the sorption isotherm, the extent of sorption,
and the desorption kinetics suggested that there was a surface interaction
(adsorption) between 3CDF and Teflon which took place mainly inside the
pores of the granules. The kinetics of desorption could be ascribed to
sorption-retarded radial diffusion inside the granules since the desorption
rate not only was correlated with the sorbed-phase concentration, but also
depended on the equilibration status of sorption, since (i) the high
initial desorption rate sharply declined because of the depletion of 3CDF
in the outermost parts of the granules, but high rates were observed again
after the system had been given time to reequilibrate, and (ii) the initial
desorption rate was higher when the preceding contact time between sorbate
and sorbent was shorter (i.e., most 3CDF was still located in the exterior
parts of the granules). These characteristics were observed irrespective of
whether the desorption was driven by percolating water through the sorbent
or by attaching active bacteria to the sorbent. 3CDF consumption by
attached cells drove 3CDF desorption to a considerable extent. The attached
cells were thus efficiently supplied with desorbing 3CDF. On the basis of
our results, we propose that the rate at which a sorbed substrate becomes
available for organisms is influenced by (i) the specific affinity of the
degrading organisms (i.e., their ability to reduce the aqueous substrate
concentration) and (ii) the tendency of the organisms to adhere to the
sorbent.
Copyright © 1995, American Society for Microbiology
Bioavailability of Sorbed 3-Chlorodibenzofuran
Department of Microbiology, Wageningen Agricultural University, 6703 CT Wageningen, The Netherlands
This article has been cited by other articles:
| J. Bacteriol. | Microbiol. Mol. Biol. Rev. | Eukaryot. Cell | All ASM Journals |
|---|