Recent advances in textile wastewater treatment using microbial consortia

During the past few decades, water resources are getting scarcer due to exponential increase in population, agriculture, urbanization and industrialization.1–4 Different industrial sectors entail significant environmental and public health concerns. One such industry is textile dyeing which is one of the most water-intensive industries and generates releases consisting of recalcitrant organic molecules generally, problems of color, high concentrations of Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), fibers, surfactants, detergents and solvents.5 Textile industries consume huge volumes of freshwater for its various wet processes and release equal amounts of wastewaters.6 During the dyeing process, not all the dyes are fixed to the fabrics. There is always a portion of unfixed dye which is discharged into the wastewater that forms the major pollutant in this effluent. Textile market utilize more than half of world dye and organic pigment, and the demand is expected to increase more than $30 billion in 2019.7 Different types of dyes are used in textile industries, the most commonly frequent dyes applied in dyeing units are azo dyes. Apart from textile industry, they are also used in tannery, paper and pulp, pharmaceutical, food, paint, plastics, cosmetics and electroplating industries.8 The improper discharge of colored dye effluents into natural water bodies severely affects all living forms and causes aesthetical unpleasantness creating a significant problem to human being.9,10 Removal of dyes from effluent has been given a top priority. Several physico-chemical methods have been employed but they have facing several problems, such as generation of toxic by-products and economical unfeasibility.10,11 Bioremediation has become a very special challenge since it is cost-effective, eco-friendly and does not produce a large quantity of sludge.12 Several studies have focused on the utilization of pure culture to decolorize synthetic dyes. Due to the chemical complexity of these dyes, it is necessary to develop more efficient microbial processes for decolorization.10 Recently, trend is shifting towards use of microbial consortia. Several microbial consortia have been reported for efficient dye removal.13 In this study the main aim is to emphasize on the existing literature on microbial decolorization of TWWs using co-cultivated microorganisms.