Exploring effective methods for indigo dye removal and recovery from textile effluent: a sustainable approach towards resource recovery

The textile industry is reported as one of the most pollution-producing industries because of toxic colorants that are hard to remove by conventional treatment methods. These colorants have highly negative impacts on ecology and aquatic biota. Dye, which is a valuable resource, is discharged as waste in the effluent and is considered as an environmental threat, because of its low degradability. If this dye is recovered from wastewater, on the one side it can be reused and can give financial benefits, and on the other hand, its removal from the wastewater can be a secondary advantage for the environment as wastewater treatment could be simplified. Though various methods for the discoloration of textile effluent have been reported in the literature, but many of them are either expensive, inefficient, or environmentally unfriendly. The reported methods in the literature have different removal mechanisms which can be categorized as degrading mechanisms and non-degrading mechanisms. Though the removal of various dyes including indigo carmine is possible through both mechanisms, however for the recovery of these dyes from wastewater one should adopt a non-degrading mechanism. This article summarizes various reported dye removal methods and will relate the suitability of these methods and the extent to which they are suitable for dye recovery. Based on the nature of the treatment these methods are subclassified as physical, chemical, Physicochemical, biological, and physico-biological methods and this article will encapsulate the adaptivity, massiveness, and immensity of these methods for indigo dye removal and recovery. Upto 100% removal has been attained through various methods among which adsorption and filtration are the most feasible methods for recovery of Indigo dye from effluent.