Sunday, July 26, 2009
P71
Decolorization of the azo dye methyl red in high salinity environment
Yoram Shotland, Leonardo Bielenki, Christina Dlugy, Dorith Tavor, and Adi Wolfson. Green Processes Center, Chemical Engineering Department, Sami Shamoon College of Engineering, Bialik/Basel Sts., Beer-Sheva, Israel
Synthetic dyes are used for various industrial applications: textile dyeing, paper printing, color photography, pharmaceutics, cosmetics, and other applications. Azo dyes, which represent the largest and most versatile class of synthetic dyes, are difficult to decompose due to their complex structure and synthetic nature. Moreover, most of the azo dyes and their degradation products are cytotoxic and carcinogenic. Physical and chemical techniques for the treatment of dye contaminated wastewater are highly cost and produce secondary pollution. Biological treatment of wastewater containing dyes, however, is usually cheaper. Moreover, microbial degradation of these dyes will have almost no harm for the environment. Yet, the high salt concentration accompanying the industrial dye wastewaters cause plasmolysis and cell death. Thus, finding a salt-tolerant and efficient bio-treatment system for the degradation of dyes in high saline wastewaters is a challenge.
In this work we show for the first time that the ability of the nonpathogenic bacteria Staphylococcus cohnii to survive and propagate in high salinity environment is as good as its known salt tolerant pathogen relative Staphylococcus aureus. Both bacteria showed high resistance up to 15% NaCl, whereas concentration of salt in wastewater from textile dyes is about 12%. Furthermore we tested the ability of the bacteria to decolorize azo dyes in different salinity levels. Both bacteria were able to completely decolorize the azo dye methyl red while Staphylococcus aureus was somewhat faster. However, the important advantage of performing dye-decolorization with Staphylococcus cohnii, a nonpathogenic salt tolerant bacterium, is clear.
In this work we show for the first time that the ability of the nonpathogenic bacteria Staphylococcus cohnii to survive and propagate in high salinity environment is as good as its known salt tolerant pathogen relative Staphylococcus aureus. Both bacteria showed high resistance up to 15% NaCl, whereas concentration of salt in wastewater from textile dyes is about 12%. Furthermore we tested the ability of the bacteria to decolorize azo dyes in different salinity levels. Both bacteria were able to completely decolorize the azo dye methyl red while Staphylococcus aureus was somewhat faster. However, the important advantage of performing dye-decolorization with Staphylococcus cohnii, a nonpathogenic salt tolerant bacterium, is clear.
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