Researchers at IIT Guwahati have developed a biological treatment approach that degraded 98.5% of the synthetic textile dye Direct Blue-6 under optimised laboratory conditions.
Researchers at the Indian Institute of Technology Guwahati (IIT Guwahati) have developed a bacterial approach for treating textile wastewater containing persistent synthetic azo dyes. The research uses a novel bacterium, Brevundimonas sp. AJZ05, which demonstrated the ability to degrade 98.50% of Direct Blue-6 (DB-6) under optimised laboratory conditions.
Direct Blue-6 is a synthetic azo dye used in textile processing. Its stable chemical structure makes it difficult to remove through several conventional wastewater treatment methods. The researchers focused on breaking down the dye rather than simply removing its visible colour from contaminated water.
The IIT Guwahati team isolated Brevundimonas sp. AJZ05 from a native textile effluent discharge site. The bacterium produces azoreductase, an enzyme capable of attacking the azo bond responsible for the colour and chemical stability of many synthetic dyes.
Using a statistical optimisation approach based on Response Surface Methodology, the researchers simultaneously optimised dye degradation and azoreductase production. Under the optimised conditions, the bacterium achieved 98.50% degradation of Direct Blue-6, with azoreductase activity reaching 0.761 U/mL.
An important part of the study was the assessment of the substances produced during biodegradation. The researchers analysed the metabolites formed after treatment and found that the degradation products were non-toxic, suggesting that the process could transform the dye into safer compounds rather than only reducing wastewater colour.
The biological approach could provide an alternative or complementary method to chemical and physicochemical wastewater treatment processes. Conventional methods can require significant energy or chemicals and may sometimes generate secondary pollutants.
The researchers also found that the bacterium can tolerate several metal ions. This characteristic could be relevant to industrial wastewater treatment because textile effluents may contain mixtures of dyes and other contaminants.
The technology is currently at the laboratory research stage. The next phase involves immobilising Brevundimonas sp. AJZ05 in a suitable support matrix to improve its stability, operational performance and reusability. The team also plans to develop a continuous treatment system for azo-dye removal from textile wastewater.
The research was supported by the Ministry of Education through the Prime Minister’s Research Fellowship, with support from the Department of Chemical Engineering & Technology at IIT (BHU), Varanasi. The findings were published in the peer-reviewed journal Environmental Geochemistry and Health.
For textile manufacturers and wastewater-treatment developers, the research highlights the potential of microbial systems to address persistent dye pollutants. Further work on scalability, continuous operation and performance under actual industrial wastewater conditions will determine how the laboratory findings can be translated into commercial treatment systems.
The development adds to ongoing research into biological wastewater treatment and offers a potential pathway for reducing the environmental impact of dye-containing textile effluents.