الفهرس 
Azo degradation and decoloration by bacterial mixed cultures and consortiaOnly 14 pages are availabe for public view
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Abstract
Bio-treatment has been demonstrated to be the most efficient,
environmentally friendly, and cost-effective technique in order to treat of
wastewater contaminated with textile dyes. Synthetic dyes widely used in
the commercial textile industry constitute, When released into an aqueous
environment, it becomes hazardous and recalcitrant.. In the present study,
water quality assessment studies for wastewater contaminated with textile
dyes have been studied by evaluating the physical-chemical and
microbiological profile for 10 water samples collected from 10 different
sites. Different microbial consortia collected from the different 10 sites
were screened for their abilities of decolorization of five dyes used
extensively in the textile industry. Factors affecting bio-decolorization
such as; inoculum size, dye concentration, solution pH, incubation
temperature, and incubation time were studied. Isolation, purification, and
identification of bacterial strains showed the high capability to decolorize
dyes were performed. Ten bacterial consortia were collected from the
different water sites using an enrichment technique by methylene blue
dye. The optimum conditions under which they could show the high
capability of bio-decolorization were 107, 200 mg-1, 7, and 30oC for
inoculum size, dye concentration, solution pH, and incubation
temperature, respectively. Twelve potential bacterial strains were isolated
from the best 4 consortia capable of degrading different dyes through the
study. Made mixed groups of twelve strains and then choose the best mix
in decolorization activity Using 16S rRNA sequence analysis on the best
mix in Biodegradation, the bacterial strains were identified as Bacillus
subtilis, Bacillus megaterium, Bacillus cereus.
Further biodegradation studies were carried out using Direct red 81
dye at a concentration of 200 mg L-1 and B. cereus at an incubation
temperature of 30oC for 24h. The by-products of biodegradation were
followed up by Liquid chromatography- mass spectrometry LC-MS.
A textile wastewater sample contaminated with red color was
obtained from 10th of Ramadan city treatment plant station, of it, 2 L
have been inoculated with Bacillus cereus for 10 days at room
temperature 25oC. The fate of the original dye (Direct red 81) after
treatment with B. cereus was followed up by LC-MS, which confirmed
the degradation of Direct red 81 dye by B. cereus to small aliphatic
compounds and then CO2. The use of B. cereus in decolorizing textile
wastewater contaminated with red color was achieved after 10 days of
incubation with color removing of 98% at ambient conditions. The
chemical oxygen demand COD and Total organic carbon TOC of the
wastewater sample were reduced by 78.6 % and 69.3 %, respectively.
Yeast may be less expensive and better than other
microorganisms. This experiment attempted to investigate the
decolorization of blue coloring in methylene blue by Saccharomyces
cerevisiae. The study was conducted to determine the best conditions in
which the maximum decolorization occurred. The highest decolorization
was monitored at 30oC and a concentration of 100 ppm (0,01g/100ml),
during which a maximum decolorization of 95,95% occurred after the 20
h incubation period. In the next assay at concentrations of 100 ppm
(0.01g/100 ml) and pH 7 for 20 h, accumulative decolorization of 98.90%
has been obtained at dosages of 0.1 gram/l with 30oC, which is considered
as the best conditions. Saccharomyces cerevisiae was able to handle the
textile wastewater in optimal conditions.