A DBT supported project developed phytoremediation treatment process for the degradation of dyes from textile industrial effluent.
The study showed that Macrophytes Ipomea aquatic, Alternanthera philoxeroides (a massively rooted macrophyte), and Salvinia molesta showed a potential for textile dyes and effluent treatment.
A. philoxeroides, S. molesta and I. hederifolia can efficiently be used for the treatment of textile industry effluent at large scale (constructed wetland system) through rhizofiltration approach.
Ipomoea aquatica, a macrophyte was found to degrade a highly sulfonated and diazo textile dye Brown 5R up to 94% within 72 hours at a concentration of 200 mg L-1. Induction in activities of different oxido-reductive enzyme was observed in response to Brown 5R dye exposure. Toxicity study on HepG2 cell lines showed a threefold decrease in toxicity of a parent dye Brown 5R after phytoremediation by I. aquatica.
Rhizofiltration with I. aquatica and soil bed treatment by I. hederifolia treated 510 L of effluent effectively within 72 h. I. aquatica along with I. hederifolia could decolorize textile industry effluent within 72 h of treatment which was evident from the significant reductions in the values of COD, BOD, total solids and ADMI.
Salvinia molesta, an aquatic fern is potent of degrading azo dye ‘Rubine GFL’ to 97% at concentration of 100 mg L-1 within 72 h. The real textile industry effluent was decolorized by S. molesta in lagoon (52,200 L) within 192 h which significantly reduces the value of COD, BOD, ADMI, pH and metal ions.
Alternanthera philoxeroides, an alligator weed, by virtue of its ability to survive in extreme environmental conditions could completely decolorize RR dye within 72 h. A. philoxeroides also demonstrated its potential in decolorizing real textile industry effluent of varying pH at laboratory and pilot scale. The enzyme expression patterns of A. philoxeroides during the course of decolorization were also suggestive of having role of different oxido-reductases in decolorization of RR.
Predominantly, an anatomical understanding of the decolorization in actual plant tissues was also made through histological analysis. The fish toxicity analysis with Devario aequipinnatus at histological level proved A. philoxeroides as an efficient phytoremediator in cleaning up and detoxification of contaminated waters.
Further, on field application of I. aquatica, S. molesta and A. philoxeroides in waste water lagoon systems was successfully carried out. Studies to explore these plants in a constructed wetland system for textile effluent treatment at an industrial scale are underway.