Bacterial decolorization of textile industry effluent
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Date
2015
Authors
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Journal ISSN
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Publisher
CCSHAU
Abstract
Textile industries discharge large volumes of colored effluent that is a threat to the environment. Color is
the first contaminant to be recognized in waste water and has to be removed before discharging into water bodies or
on land. Biological treatment is a promising approach for the effective decolorization of textile effluent. Hence, the
present investigation was carried out with two objectives (i) Screening of textile industry effluent decolorizing
bacteria, and (ii) Optimization of culture conditions for maximum decolorization of textile effluent. In the present
study, three dyes Congo red, Yellow CRG and Yellow 5G and two textiles effluent samples (BTM and PTM) were
used for decolorization studies. A total of 60 bacterial isolates were obtained by enrichment culture technique from
different sources and screened for their ability to decolorize dyes and effluents. Four bacterial isolates (TS-1, TS-2,
TS-10 and TE-12) for Congo red and Yellow CRG, five (TS-1, TS-5, TS-8, TS-11 and TE-14) for Yellow 5G and
four (TS-1, TS-2, ES-27 and ES-28) for BTM and PTM effluents were selected on the basis of their decolorization
potential (>40%). Decolorization efficiency was determined with respect to time and dye concentration and all the
isolates were able to decolorize as high as 250ppm of Congo red, 80ppm of Yellow CRG, 60ppm of Yellow 5G dyes
and crude effluent in 72 h. Mechanism of decolorization was adsorption. Optimization of culture conditions was
carried out with different parameters and maximum decolorization was obtained under shake culture conditions with
1.0% inoculum size. Maximum decolorization was observed when sucrose and ammonium chloride were used as
carbon and nitrogen source in all dyes, while glucose and yeast extract in effluents. Optimum temperature and pH
for decolorization of dyes and effluents were 35
0
C and 7.0 respectively. Decolorized dyes and effluents were
less inhibitory to seed germination and seedling growth in comparison to untreated dyes and effluents. On
the basis of various standard morphological and biochemical tests, the bacterial isolates TS-1, TS-10, TE-12 were
tentatively identified as Bacillus, TS-2 as Pseudomonas and ES-28 as Paenibacillus.
Description
Keywords
Dyes, Decolorization, Optimization, Textile effluent, Toxicity