Process development for the degradation of industrial Azo dyes by microbial and gamma irradiation augmented approach

Abstract

Rapid industrialization and urbanization resulted in the discharge of enormous amount of waste to the environment which in turn affects the ecosystem Textile industries one of the India s largest water consumers generate highly toxic effluent containing recalcitrant agents such as dyes sizing agents and dying aids Azo dyes represent a major group of reactive dyes 80% are considered as the electron deficient compounds as they possess the electron withdrawing groups like azo N N and sulphonic SO3 which makes the compound less susceptible to oxidative degradation The general approach of bioremediation is to improve the natural degradation capacity of the native organism Most important challenge which limits the application of this technology at industrial scale is slow rate of degradation In this study, the dye degrading microorganism was screened from four different sites Out of 27 morphologically different colonies based on the percentage of degradation one isolate RAPT1 was isolated The isolate was characterized and named as Bacillus cohnii RAPT1 The organism was grown in NY medium The process parameters were optimized using One Variable At a Time approach OVAT The effect of growth time number of cells concentration of NaCl pH temperature and concentration of dye were optimized as 12h 100 106 CFU ml 4 7 0 35C and 200mg L respectively The bacterial cells were immobilized onto the pre-treated PSF cultivated in NY medium at pH 7 0 35 C for 24h with initial inoculum size as 500 106 CFUmL The performance of free cells and immobilized cells in Batch Reactor was compared with continuous packed bed reactor newline