Designing and Optimization of Sustainable Biological System for the Effective Removal of Azo Dyes from the Textile Industrial Waste

Abstract

Clothing is an essential segment in the life of modern human beings. It fulfils basic social demands i.e., fashion, and tends to provide employment to millions of people. Textile industry uses a variety of substrates, for example, colorants, surfactants, salts, acids, and pigments. During the dye application process, textile industries discharge gallons of colored wastewater into the environment. Discharged wastewater is highly toxic due to the presence of carcinogenic compounds like organic molecules, heavy metals, synthetic dyes, and odorants. Environmental regulations are becoming more stringent, which is impelling industries to develop economical, efficient, and technically feasible methods for the treatment of toxic dyes before discharge. Among various synthetic colorants, azo dyes represented by the characteristic N=N bond is the most diverse group, widely being employed in industries. As highly toxic and reconstituted compounds, azo dyes pose a threat to plants, animals, and humans. Conventional treatment methods are of limited applicability due to use of toxic chemicals, intensive energy requirement, high cost, and generation of secondary sludge. Biodecolorization, a biological method of dye removal from colored wastewater is an emerging approach. The current research study reports the sustainable biological method for the effective treatment of azo dyes. Three bacterial strains viz., Enterococcus sp. AV1, Priestia sp. RA1, and Bacillus sp. RA5 were identified and characterized for the biodecolorization of various azo dyes. Analytical methods such as UV-Vis spectroscopy, Fourier transform infrared spectroscopy and gas chromatography mass spectrometry were used to confirm dye decolorization. For the development of an excellent and efficient decolorization system, effect of abiotic factors on dye decolorization and kinetic studies were also performed. newline