Immobilized Pseudomonas luteola able to reduce azo groups enzymically were
used as a biocatalyst for the decolorization of wastewater containing azo d
yes. Cells of P. luteola were immobilized by entrapment in natural and synt
hetic polymeric matrices. The effects of operational conditions (e.g., temp
erature, pH, dye concentration, etc.) on microbial decolorization were inve
stigated. The reusability of the immobilized biocatalyst was evaluated with
repeated-batch decolorization experiments. Immobilized cells were less sen
sitive to agitation rates (dissolved oxygen levels) and pH as compared with
suspended cells, while the effects of temperature were similar for both su
spended and immobilized cells. Michaelis-Menten kinetics was used to descri
be the apparent correlation between the decolorization rate and the dye con
centration. After four repeated experiments. the decolorization rate of the
free cells decreased by nearly 45%, while CA-, CGN-, and PAA-immobilized c
ells retained over 75, 85, and 80% of their original activity, respectively
. The time required for 50%, conversion (t(1/2)) remained nearly the same f
or CGN- and PAA-immobilized cells during four cycles, indicating the stable
decolorization efficiency of these immobilized cells. (C) 2001 Elsevier Sc
ience Ltd. All rights reserved.