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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

Indigo is not readily biodegradable. However, tests for colour and COD removal show that it can be to more than 90% removed within up to 60 days using anaerobic bacteria.

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Additional information

Indigo is not readily biodegradable. However, anaerobic and aerobic treatment of the textile effluent were both effective in reducing the wastewater colour within 45 and 90 days, respectively. However, anaerobic treatment generally produced the greatest colour removal (68-97%) at a much shorter time. Peptostreptococcus spp. and B. fragilis because of their relatively higher pH-tolerance can be used together with E. coli for the efficient decolourization and degradation of textile effluents containing Indigo dye.

In a further test, using a mixed culture of anaerobic bacteria of a sewage plant in a semi-continuous bioreactor, colour removal of up to 95% and COD removal of up to 90% could be achieved within 60 and 50 days of incubation, respectively.