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IntroductionThe textile industry in India is one of the oldest industries. It provides direct employment to nearly thirty million people. Wastewater from the textile industries are a complex mixture of many polluting substances such as organo chlorine-based pesticides, heavy metals, pigments and dyes. The dye that has been chosen for this study is Reactive Black. This study focused on microbial degradation and decolourisation of Reactive Black by an application of Pseudomonas stutzeri ETL-79. Materials and methodsThe decolourising bacterium was identified as P. stutzeri ETL-79 based on physiological and biochemical characteristics as well as the 16S rRNA sequence. In this study, the effects of P. stutzeri ETL-79's decolourising ability, for example, glucose concentration, temperature, pH and dye concentration, were investigated. ResultsThe results show that under 40°C, pH 7.0, glucose concentration 0.2% and concentration of Reactive Black of 30 mg/L the decolourisation rate in 24 and 48 hours was 86.3% and 93.2%, respectively. ConclusionThe study concluded that pH, temperature and various carbon sources have a significant influence on the dye removal efficiency by P. stutzeri ETL-79. This shows that the isolated becomes uneconomical and causes further environmental damage. Hence, economical and eco-friendly techniques using bacteria can be used for fine-tuning of wastewater treatment. Bio-treatment offers an easy, cheap and effective alternative for colour removal of textile dyes.

Introduction Isolation and identification of dye decolourizing bacterial isolate from textile dye effluent was carried out. The isolate of Bacillus subtilis ETL-2211 was isolated from the textile effluent samples collected from textile industries of Ankleshwar, Gujarat, India. Different parameters were used for optimizations. The aim of this study was to discuss the microbiological removal of crystal violet dye by B. subtilis ETL-2211. Results The results showed that temperature (40°C), pH (8.00), biological oxygen demand (220 mg l-1), chemical oxygen demand (700 mg l-1), total suspended solids (2800 mg l-1), total dissolved solids (7500 mg l-1) and colour over the prescribed fresh water limits. A potential bacterial strain was isolated and selected from the textile effluent on the basis of rapid azo dye crystal violet (100 mg l-1) decolourization and later identified as B. subtilis based on phylogenetic and phenotypic characterization. Effects of physicochemical parameters (pH, temperature, etc.) on crystal violet decolourization by B. subtilis ETL-2211 were studied. Discussion Decolourization was effective at pH 8, 35°C with starch and peptone as carbon and nitrogen sources and in static conditions. This decolourization potential increased the applicability of this microorganism for dye removal. Conclusion The study concluded that pH, temperature and various carbon and nitrogen sources have a significant influence on dye removal efficiency by B. subtilis ETL-2211. This shows that the isolated bacterium has enormous potential to degrade the textile dyes and resolve the problem of unnecessary dyes present in the effluents of textile industries.

IntroductionIn this study, an attempt was made to examine the potential of two bacterial strains for decolourisation of Acid Orange 10. The strain, isolated from textile effluent treatment plant was characterised on the basis of morphological, biochemical and genotypic characteristics, and it was identified as Pseudomonas aeruginosa and Bacillus cereus. The effect of pH, temperature and initial concentration of dye was studied with an aim to determine the optimal conditions. Materials and methodsThe bacterial strains used in this study were P. aeruginosa ETL-1942 and B. cereus ETL-1949. Out of these two, P. aeruginosa ETL-1942 emerged as the most potent decolouriser, being selected for further studies. ResultsThe selected bacterium shows higher decolourisation in the static condition compared to the shaking condition. The optimum pH was 7.0. It shows good decolourisation efficiency even in the alkaline region. The optimum temperature was 37°C. The strain could decolourise Acid Orange 10 (250 mg/l) by 94% within 24 hours under static conditions, pH 7.0, temperature of 37°C and initial dye concentration of 250 mg/l.

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