Abstract
The study aims to isolate and optimize bacterial strains having the ability to degrade and decolorize azo dyes produced in the final effluent of textile dying industries. In this regard, ten bacterial strains were isolated from wastewater treatment plants, and most of them were subjected to the colored effluents resulting from dilapidated houses. The ability of these bacterial isolations to use a wide range of azo dyes to determine the sole carbon source was determined. According to these screening testes, two bacterial isolations were selected as the most potent decolorizer for azo dyes, and they were identified as Comamanas acidovorns-TN1 and Burkholdera cepace-TN5. The optimization process started with the addition of 1 g/l yeast extract, where the decolorization ability of the two strains increased sharply and according to this experiment, the two azo dyes, Acid orange 7 and Direct blue 75, were selected to complete the study. The effect of different conditional and chemical factors on the decolorization process of Acid orange 7 and Direct blue 75 by Comamanas acidovorns-TN1 and Burkholdera cepace-TN5 was studied. Factors that contributed to the difference were different pH, temperature, incubation period, inoculum size, carbon source, nitrogen source and the respective concentrations of yeast extract. This study recommends the application of the two most potent bacterial strains in the decolorization of the azo dyes, along with acid orange 7 and direct blue 75, specifically in the industrial effluents under all nutritional and environmental conditions.
Highlights
Environmental pollution has been identified as a major problem in the modern world
Partial absorption and membrane filtration techniques lead to secondary waste streams which need further treatment. These constraints have led to the adoption of advanced oxidation processes (AOP) and biological methods as attractive options for the treatment of dye-containing wastewaters
AOP is defined as those processes that use strong oxidizing agents (H2O2, Fenton’s reagent) or heterogenous photocatalysts, such as TiO2, ZnO2, Mn, or Fe in the presence or absence of an irradiation source
Summary
Environmental pollution has been identified as a major problem in the modern world. The increasing demand for drinkable water, and its dwindling supply, has made the treatment and reuse of industrial effluents an attractive option. The largest chemical class of dyes with the greatest variety of colors, have been used extensively for textile, dyeing, and paper painting [1]. These dyes cannot be degraded, and some are toxic to higher animals. Advanced oxidation processes (Ozonation, UV/H2O2) are based on the generation of hydroxyl radicals, which are mainly highly reactive oxidants They are environmental friendly techniques, since no solid wastes are produced. They are not cost effective due to the high consumption of both energy and raw material (e.g. hydrogen peroxide). The main disadvantage of these methods is the production of a secondary waste stream (or waste solid) that requires further treatment or disposal
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