ABSTRACT
There has been a continuous upsurge in production and supply of textiles with the increasing population of the world. More than 10,000 different synthetic dyes, up to an amount of 7 × 104 tons per year, are utilized worldwide to procure colorful fabrics. It should be noted that 20 percent of dye stuff is released in the wastewater generated after processing. These dyes are toxic xenobiotic chemicals that have been reported to cause carcinogenic, mutagenic, allergic, and cytotoxic effects on aquatic and terrestrial living beings, including humans. The treatment of these wastewaters has therefore been made mandatory to dye-processing units and legislations are well in place. However, issues such as costs, secondary pollution generation, on field administration and incomplete/partial treatment make it difficult for industries to follow the set guidelines. Because of the shortcoming of physicochemical methods of dye-effluent treatment, modern bioremediation approaches are generally followed as alternatives. Use of bacteria, fungi, yeasts, and even algae are proposed but possess limitations when in situ treatment is concerned. In the last few decades, use of vegetation for pollution management called phytoremediation has been proposed to achieve notable treatment of dye effluents as an eco-friendly, green, passive, solar energy–driven, and sustainable method of dye effluent treatment. Plants of various forms/habits, such as garden ornamentals, weeds, grasses, and aquatic macrophytes have been discovered for the treatment of textile effluents. Various oxido-reductases, such as lignin peroxidase, vertryl alcohol oxidase, tyrosinase, laccase, azo reductase, riboflavin reductase, superoxide dismutase, catalase, glutathione peroxidase, and so on are known to degrade textile dyes. In vitro cultures of plants have been shown to be able to remove textile dyes, revealing direct involvement of plants in dye metabolism. Several pilot scale reactors/constructed wetlands are also on record to show significant treatment and detoxification of dye effluents, achieving a noteworthy decline in environmentally important parameters such as chemical oxygen demand, biological oxygen demand, total organic carbon, total suspended solids, total dissolved solids, American Dye Manufacturers Institute color removal value, turbidity, and conductivity. Additionally, more scientific intervention to deal with actual hydraulics and pollutant load needs to be addressed to endorse phytoremediation for further applications.
