IIT Guwahati, IIT BHU develop researchers eco-friendly bacterial approach to treat textile wastewater

Researchers from the Indian Institute of Technology (IIT) Guwahati and IIT BHU have developed an eco-friendly biological method to treat textile wastewater containing toxic azo dyes, officials said on September 16.

The research demonstrates the potential of a novel bacterium, ‘Brevundimonas sp. AJZ05’, to degrade 98.50 per cent of Direct Blue-6 (DB-6), a widely used synthetic textile dye. The degradation products formed after bacterial treatment were also found to be non-toxic, according to the researchers.

The findings have been published in Environmental Geochemistry and Health, a peer-reviewed journal focusing on research linking environmental and health concerns.

According to Selvaraju Narayanasamy, Associate Professor at the Biochemical and Environmental Engineering Laboratory, the study provides a scientific foundation for developing biological treatment systems for textile wastewater containing azo dyes.

Azo dyes are difficult to remove because of their stable chemical structure. The characteristic azo bond (–N=N–) contributes to both the colour and chemical stability of these dyes, making them resistant to several conventional treatment processes. Untreated textile effluents can pose risks to aquatic ecosystems and may have implications for human health.

The researchers isolated Brevundimonas sp. AJZ05 from a native textile effluent discharge site. The bacterium was found to produce azoreductase, an enzyme capable of breaking down the azo bond responsible for the dyes’ colour and stability.

Using a statistical multi-objective optimisation approach based on Response Surface Methodology, the team simultaneously optimised dye degradation and azoreductase production.

Importantly, the researchers went beyond measuring colour removal and analysed the metabolites produced during the biodegradation process. Toxicity assessment showed that the degradation products were non-toxic after bacterial treatment, suggesting that the process could transform the dye into safer compounds rather than merely removing its visible colour.

Narayanasamy said the approach could serve as an eco-friendly alternative or complement to conventional chemical and physicochemical wastewater treatment methods, which can be energy-intensive and may generate secondary pollutants.

The research team is now working to translate the laboratory-scale findings into a practical and scalable treatment technology. The next phase involves developing a continuous treatment system for azo-dye removal from textile wastewater, with the long-term objective of advancing the microbial platform towards industrial application.