Dye Pollution in Water and Wastewater

The presence of dye in water stream leads to unexceptional effects on living life. As dyes are consumed globally from small-scale to large-scale industries inculcating tanneries, food, cosmetic, textile, medicinal sectors with the production of 1,000,000 tons all over the world. Majorly, the textile sector plays a pertinent role in dye emissions into the ecosystem. Only dying industries discharge about 7.5 metric tons annually. The complex structures of dye comprising of aromatic rings bonded with different functional groups having π-electron could absorb light within 380–700 nm spectra. They impart coloration due to the presence of chromogens and chromophores. Out of several natural and synthetic dyes, azo group proliferation has been highly carcinogenic due to amine and benzidine emissions. Besides this, the fact of being non-biodegradable makes the dye molecules last longer in the environment producing hazards. Henceforth, eradication of dye molecules from wastewater is thus needed before discharging the stream into the environment with long- and short-term effects. The severe implications have been reported for the aquatic life due to direct contact. Whereas to human life, there were observations from skin irritations to cancer-like disease. Several approaches were reported for the treatment of dye-containing streams but the exploration for the best available technique is still ongoing. So, this chapter collects comprehensive facts about dyes, its harmful effect, and approaches for the treatment at a worldwide level and Indian perspective. Additionally, the article draws out the comparative analysis for available techniques and states the recent advancements for the purification of dye-containing wastewater.