Environmental Engineering Reference
In-Depth Information
dyes and related colored byproducts, as reviewed by Rodríguez-Couto [46].
In many cases, the wastewater was supplemented and/or diluted with
nutrient solutions, such as culture media containing carbon and nitrogen
sources and other trace nutrients. Knapp and Newby [53] investigated the
treatment of an effluent from the manufacture of nitrated stilbene sulfonic
acids that contain diazo-linked aminostilbene-2,2'-disulfonic acid units
with nitro groups using five strains of white rot fungi including
P. chryso-
sporium
,
T. versicolor
,
P. ostreatus
, and
Piptoporus betulinus
. They found
that up to 80% of color removal was achieved by all strains and that a strain
of
T. versicolor
showed the best performance. Selvam
et al.
[80] reported
somewhat modest decolorization of a dyeing industry effluent using both
mycelia of
Thelephora
sp. and purified laccase from this fungus. Up to
61% and 15% of initial color was removed by the mycelia and the puri-
fied enzyme in a batch mode, respectively. Nelsson
et al.
[70] treated a real
wastewater from a textile industry in Tanzania using a packed bed reac-
tor with natural luffa sponge inoculated with
Pleurotus fabellatus
. he tex-
tile wastewater was autoclaved and mixed with a nutrient solution. The
pH of the wastewater was adjusted to 3 to 4. The working volume of the
bioreactor was 1.5 L and the wastewater was introduced at a flow rate of
59 mL/h that corresponded to an HRT of 25.4 h. Sathiya
et al.
[55] treated
a dye house effluent in India with
T. hir s ut a
and
Pleurotus florida
in a batch
mode. They found that pH adjustment (from 11 to 6) and glucose addition
(up to 2%) could improve the decolorization of the effluent by these two
fungi. Revankar and Lele [76] and Krishnaveni and Kowsalya [67] reported
the decolorization of textile industry effluents in India using
Ganoderma
sp. and
P. florida,
, respectively. Shin [72] reported the decolorization of a
textile industry effluent in South Korea without addition of any nutrients
in shaking or stationary cultures of
I. lacteus
.
6.4
Fungal Decolorization Mechanisms and
Involvement of Ligninolytic Enzymes
Virtually all the fungi discussed in Section 6.3 are well-known lignino-
lytic species that produce high levels of ligninolytic enzymes including
laccase, LiP, MnP, and/or manganese-independent peroxidase (versa-
tile peroxidase and DyP) [16], and the major role of those ligninolytic
enzymes in dye decolorization has been suggested since the early days
[22,24,32,47]. Other significant decolorization mechanisms include sorp-
tion to mycelia and biodegradation other than the ligninolytic mechanism
[22,43,45], although their contributions are relatively minor. Therefore,
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