Microbe-Mediated Degradation of Synthetic Dyes in Wastewater - Microbial Degradation of Synthetic Dyes in Wastewaters - page 204

Table 1 (continued)
Sl.
No.

Process Advantages Disadvantages References

F. Advanced oxi-

dation pro-
cesses, AOPs

Generate a large
number of highly
reactive free radi-
cals and by far sur-
pass the
conventional oxi-
dants in
decolorization

AOPs in general
may produce fur-
ther undesirable
toxic by-products
and complete min-
eralization may not
be possible. Pres-
ences of radical
scavengers reduce
efciency of the
processes some of
which are pH
dependent. Cost-
prohibitive at their
present stage of
development

Robinson et al.
( 2001 ), Slocker
and Marechal
( 1998 )

1. UV/O 3 Applied in gaseous

state, no alteration
of volume. Good
removal of almost
all types of dyes;
especially suitable
for reactive dyes.
Involves no sludge
formation, necessi-
tates short reaction
times

Removal is pH
dependent (neutral
to slightly alka-
line); poor removal
of disperse dyes.
Problematic han-
dling, impose addi-
tional loading of
water with ozone.
Negligible or no
COD removal.
High cost of gener-
ation coupled with
very short half-life
and gas-liquid mass
transfer limitation;
suffer

Fu and Viraragha-
van ( 2001 ), Gogate
and Pandit ( 2004 ),
Hao et al. ( 2000 ),
Ince et al. ( 2002 ),
Marachel et al.
( 1997 ), Robinson
et al. ( 2001 )

2. UV/H 2 O 2 Involves no sludge

formation, necessi-
tates short reaction
times and reduction
of COD to some
extent may be
possible

Not applicable for
all dye types,
requires separation
of suspended solid
and suffers from
UV light penetra-
tion limitation.
Lower pH required
to nullify effect of
radical scavengers

Gogate and Pandit
( 2004 ), Marachel
et al. ( 1997 )

3. Fenton ' s Effective decolor-

ization of both sol-
uble and insoluble
dyes; applicable

Effective within
narrow pH range
of < 3.5; and
involves sludge

Hao et al. ( 2000 ),
Marachel et al.
( 1997 ), Robinson
et al. ( 2001 )
(continued)

reagent