Current perspectives, recent advancements, and efficiencies of various dye-containing wastewater treatment technologies

The usage of dyes is increasing due to their high demand in expanding industrial sector. As a result, large volumes of dye wastewater are being generated, particularly in the textile industry. Colored effluent discharged by industrial processes into surface water bodies negatively affects aquatic, human, and animal life, which is a major global concern. To reduce the detrimental effects of dye wastewater on the environment, it should be treated before its disposal. This article extensively reviews the existing and advancements in physical, physicochemical, chemical, and biological treatment technologies and their efficacies in dye removal (%). Also, the article summarized the benefits and challenges associated with the existing methods to use them at an industrial scale. The physical, physicochemical, and chemical methods have less hydraulic retention time (HRT), from minutes to a few hours, and higher removal efficiencies (85-100 %). However, certain drawbacks hinder their widespread use, such as limited regenerative capacities of adsorbents, filtration associated with high fouling rates of the membrane, higher costs of ion exchange, sludge production in coagulation-flocculation, high treatment cost and high dissolved oxygen requirement in sonocatalysis and in chemical technologies: secondary pollutants production, sludge production, high cost, and ecological inefficiency. Biological-based treatment with bacteria, fungus, yeast, and algae has a bit higher HRT (a few hours to days) with removal efficiencies ranging between 85 and 100 % with the advantage of low cost, low energy requirement, less sludge, and being environmentally friendly. Developing an environmentally friendly and low-cost method is currently the need of the hour. Researchers have increasingly focused on bioremediation as an essential method for removing dangerous dye contaminants from natural water bodies. State of the art of bioremediation techniques has also been discussed from an economic and technological standpoint.