Decolorization of mixture of dyes and dye
wastewater Synthetic dyes and pigments released to the environment
in the form of effluents by textile, leather and printing
industries cause severe ecological damages. The removal of the
polluting dyes is an important problem, however in India particularly
for small scale textile industries, where working conditions
and economic status do not allow them to treat their wastewater
before disposal and they have no choice rather than dumping all
effluent into the main stream of water resources. The composition
of textile effluent consists of a mixture of many synthetic dyes and
the effluent characteristics (such as pH, dissolved oxygen, organic,
and inorganic chemical content etc.) which depend greatly upon
the textile processing (36). Thus, the microbial population used in
the treatment process for removing color from the effluent must
have the capability of decolorizing a mixture of different dyes.
We have evaluated the decolorization ability of mixture of
various seven industrial dyes (C.I. Remazol Red, C.I. Rubin, C.I.
Scarlet RR, C.I. Brilliant Blue, C.I. Brown 3 REL, C.I. Golden Yellow
HER, C.I. Methyl Red) each at concentration (50 mg/l) and actual
textile wastewater by using Lysinibacillus sp. RGS in batch culture
at 30C under static condition. The mixture of dyes and textile
wastewater did not have a well-defined peak at the visible
absorption spectra. The ADMI color value provides a true
measure of water color, independent of hue and thus opens the
way to the more accurate definition of water and wastewater
color. The true color of the mixture of dyes and textile
wastewater measured by using ADMI 3WL suggesting that
Lysinibacillus sp. RGS could achieve higher color removal value
(87% and 72%) and higher COD reduction (69 and 62%) within
48 h and 96 h, respectively (Fig. 4A and B). Literature survey
showed that Phanerochaete sordida exhibited 90% decolorization
of the mixture of four reactive dyes within 48 h (32);
Ischnoderma resinosum showed 100% decolorization of the
mixture of two dyes after 20 days (37); isolated A. hydrophila