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This comprehensive review explores the complex environment of textile wastewater treatment technologies, highlighting both well-established and emerging techniques. Textile wastewater poses a significant environmental challenge, containing diverse contaminants and chemicals. The review presents a detailed examination of conventional treatments such as coagulation, flocculation, and biological processes, highlighting their effectiveness and limitations. In textile industry, various textile operations such as sizing, de-sizing, dyeing, bleaching, and mercerization consume large quantities of water generating effluent high in color, chemical oxygen demand, and solids. The dyes, mordants, and variety of other chemicals used in textile processing lead to effluent variable in characteristics. Furthermore, it explores innovative and emerging techniques, including advanced oxidation processes, membrane filtration, and nanotechnology-based solutions. Future perspectives in textile wastewater treatment are discussed in-depth, emphasizing the importance of interdisciplinary research, technological advancements, and the integration of circular economy principles. Numerous dyes used in the textile industry have been shown to have mutagenic, cytotoxic, and ecotoxic potential in studies. Therefore, it is necessary to assess the methods used to remediate textile waste water. Major topics including the chemical composition of textile waste water, the chemistry of the dye molecules, the selection of a treatment technique, the benefits and drawbacks of the various treatment options, and the cost of operation are also addressed. Overall, this review offers a valuable resource for researchers and industry professionals working in the textile industry, pointing towards a more sustainable and environmentally responsible future. Graphical Abstract

The production, use, and disposal of synthetic textiles potentially release a significant amount of microfibers into the environment. Studies performed on municipal wastewater treatment plants (WWTPs) effluent reported a higher presence of microfibers due to the mix of domestic laundry effluent through sewage. As municipal WWTPs receive influents from households and industries, it serves as a sink for the microfibers. However, research on textile industry WWTPs that primarily treat the textile fabric processing wastewater was not explored with the concern of microfibers. Hence, the review aims to analyze the existing literature and enlighten the impact of WWTPs on microplastic emission into the environment by specifically addressing textile industry WWTPs. The results of the review confirmed that even after 95–99% removal, municipal WWTPs can emit around 160 million microplastics per day into the environment. Microfiber was the dominant shape identified by the review. The average microfiber contamination in the WWTP sludge was estimated as 200 microfibers per gram of sludge. As far as the industry-specific effluents are analyzed, textile wet processing industries effluents contained > 1000 times higher microfibers than municipal WWTP. Despite few existing studies on textile industry effluent, the review demonstrates that, so far, no studies were performed on the sludge obtained from WWTPs that handle textile industry effluents alone. Review results pointed out that more attention should be needed to the textile wastewater research which is addressing the textile wet processing industry WWTPs. Moreover, the sludge released from these WWTPs should be considered as an important source of microfiber as they contain more quantity of microfibers than the effluent, and also, their routes to the environment are huge and easy.

The present study evaluated the performance of microalgae Chlorella vulgaris in an Enterobacter sp. MN17-assisted textile industry wastewater treatment system for decolorization, removal of heavy metals (Cu, Cr, Pb, and Cd), and chemical oxygen demand (COD). Different dilutions (5, 10, and 20%) of wastewater were prepared to decrease the pollutant toxicity for culturing microalgae and bacteria. Reduction of color, COD, and metal contents by microalgal treatment of wastewater varied greatly, while removal efficiency (RE) was significantly enhanced when endophytic bacterial strain MN17 inoculum was applied. Most notable, results were found at a 5% dilution level by Enterobacter sp. MN17-inoculated C. vulgaris medium, as chromium (Cr), cadmium (Cd), copper (Cu), and lead (Pb) concentrations were decreased from 1.32 to 0.27 mg L−1 (79% decrease), 0.79–0.14 mg L−1 (93% decrease), 1.33–0.36 mg L−1 (72% decrease), and 1.2–0.25 mg L−1 (79% decrease), respectively. The values of COD and color were also significantly decreased by 74% and 70%, respectively, by a C. vulgaris–Enterobacter sp. MN17 consortium. The present investigation revealed that bacterial inoculation of microalgae significantly enhanced the removal of coloring agents and heavy metals from textile wastewater by stimulating the growth of algal biomass. This study manifested the usefulness of microalgae–bacterial mutualism for the remediation of heavy metals, COD, and color in industrial effluents. Microalgae consortia with growth promoting bacteria could be a breakthrough for better bioremediation and bioprocess economy. Thus, further studies are needed for successful integration of microalgae–plant growth promoting bacterial (PGPB) consortium for wastewater treatments.

Fenton process was successfully applied to degrade three reactive dyes, blue 19 (RB19), red 195 (RR195), and yellow 145 (RY145), a mixture of dyes and a real textile effluent. A 23 full factorial design coupled with a response surface methodology (RSM) was conducted to evaluate the effects of H2O2, Fe2+, and dye concentration on the Fenton reaction measured by absorbance reduction (AR) as response. Considering the analysis of variance (ANOVA), the statistical models could be used to describe experimental results and to predict the process behavior. The results obtained by RSM indicated that the optimum conditions for Fenton were [H2O2] = 50 mg L−1, [Fe2+] = 0.5 mmol L−1, and dye concentration = 0.075 g L−1, obtaining up to 90% of AR. From kinetic study, the absorbance reduction for RY145 followed a second-order model, while RB19 and RR195 followed a first-order model. The mixture of dyes and the real textile effluent obtained lower AR, 56% and 22%, respectively. The phytotoxicity tests indicate that the Fenton reactions were very effective to reduce the toxicity of almost all contaminated solutions; however, for more complex solution (mixture of dyes and real effluents), a longer reactional time is necessary. Therefore, the results pointed that the Fenton reaction is very efficient in solution discoloration.

Textile dyeing consumes high volumes of water, generating proportional number of colored effluents which contain several hazardous chemical. These contaminants can implicate in significant changes in aquatic environmental, including several adverse effects to organisms in different trophic levels. The present study was developed to assess the ecotoxicological effects of textile effluent samples and reactive Red 239 dye (used in cotton dyeing) to aquatic organisms Vibrio fischeri bacteria, Daphnia similis crustacean, and Biomphalaria glabrata snail (adults and embryos). Chronic assays with lethal and sublethal effects for Daphnia similis were included and performed only for textile effluents samples. The mutagenicity was also evaluated with Salmonella /microsome assay (TA98, TA100, and YG1041 strains). V. fischeri bacteria was the most sensitive to reactive Red 239 dye (EC50 = 10.14 mg L −1 ) followed by mollusk embryos at all stages (EC50 = 116.41 to 124.14 mg L −1 ), D. similis (EC50= 389.42 mg L −1 ), and less sensitive to adult snails (LC50= 517.19 mg L −1 ). The textile effluent was toxic for all exposed organisms [E(L)C50 < 15%] and B. glabrata embryos showed different responses in the early stages of blastulae and gastrulae (EC50 = 7.60 and 7.08%) compared to advanced development stages trochophore and veliger (EC50 = 21.56 and 29.32%). Developmental and sublethal effects in B. glabrata embryos and D. similis were evidenced. In the chronic assay with effluent, the EC10/NOEC = 3% was obtained. Mutagenic effects were not detected for dye aqueous solutions neither for effluents samples. These data confirmed the importance of evaluating the effects in aquatic organisms from different trophic levels and reinforce the need for environmental aquatic protection.

Graphitic carbon nitride (g-C 3 N 4 ) was employed as a sacrificial substructure and two-dimensional support to develop magnetic cobalt ferrite-carbon nitride (CoFe 2 O 4 /g-CN) composite via a one-step solid combustion method. The catalyst activated peroxymonosulphate (PMS), through the interconversion of Co 2 + /3+ | surf . and Fe 2 + /3+ | surf . on its surface for degradation of reactive dyes (RDs). Excellent ferromagnetic nature (44.15 emu g −1 ) of the catalyst led to its efficient magnetic separation. With an optimum catalyst and PMS dose of 0.4 g L −1 and 1.5 g L −1 , 99% RD removal was achieved for textile effluent (pH 9.5–10), under UV irradiation (48 W). In-depth radical scavenging experiments and EPR analysis confirmed the dominance of radical-based degradation process. Plausible degradation and mineralization pathways of RDs were proposed through identification of intermediates by LCMS/MS analysis. In brief, this study elucidates an exclusive strategy towards the use of g-C 3 N 4 as fuel for facile synthesis of magnetic CoFe 2 O 4 /g-CN as a remarkable photocatalyst for activation of PMS towards mineralization of various industrially relevant RDs.

Phytoremediation emerges as an innovative and eco-friendly technique to remediate textile dyes with the use of various categories of plants. In recent years, ornamental plants emerge as more attractive and effective substitute in comparison to edible plants for phytoremediation. Regardless of aesthetic value, some ornamental plants can be grown to remediate the sites contaminated with dyes, heavy metals, pesticides, or other organic compounds. In this review, we focus on pioneer research on synthetic dye removal using ornamental plants and evaluate the phytoremediation capability of ornamental plants for treatment of textile effluent. This paper also emphasized specific ornamental plants having high accumulation and tolerance ability for removal of dyes. The mechanisms explored for the phytoremediation of dyes by ornamental plants have also been explained. This review will also be helpful for researchers for exploring more new ornamental plants in phytoremediation technique.

Laccases are green oxidases with a number of potential industrial applications. In this study, recombinant Bacillus subtilis CotA laccase was secreted by Escherichia coli via both the α-hemolysin secretion system and the YebF secretion system after microaerobic induction. Meanwhile, we discovered a much simpler approach for extracellular production of recombinant CotA laccase from E. coli , involving alternation of induction conditions to release recombinant CotA following intracellular expression. By optimizing the induction parameters, the extracellular yield of recombinant CotA laccase was improved from 157.4 to 2401.3 U/L after 24 h of induction. This strategy could be suitable for large-scale production of CotA laccase for industrial use. Recombinant CotA laccase was purified by Ni 2+ affinity chromatography in a single step and showed similar biochemical properties to wild-type laccase. Purified as well as crude recombinant CotA laccase efficiently decolorized seven structurally different dyes. The decolorization capability of recombinant CotA laccase under harsh conditions was investigated by incubation of the enzyme with a simulated textile effluent (STE) with pH 11.6, 3.5 % salinity and peak absorbance of 10.42. Recombinant CotA laccase efficiently decolorized 77.0 % of STE after 48 h reaction, demonstrating the potential of this enzyme for industrial dye effluent treatment.

Textile effluents are major pollutants with varied contaminants. Traditional treatment methods are costly and produce sludge, necessitating alternative, eco-friendly solutions. Biological treatment methods are receiving attention as it is proven to be cheap, environment-friendly, and highly efficient treatment methods for dye effluent on an industrial scale as compared to the other available treatment methods. The present work evaluates the bioremediation of textile effluent using a pure culture of a bacterium isolated from the soil samples contaminated with textile wastewater. The strain was identified as Achromobacter xylosoxidans KUESCCHK-6 (GenBank Accession Number: OM475749) through 16S rRNA molecular analysis. This bacterial strain was used to treat textile effluent under specific conditions: glucose as the carbon source, urea as the nitrogen source, a C/N ratio of 6:1, a temperature of 35°C, a pH of 8.5, and a static incubation period of 5 days. The results indicated that the strain effectively reduced various physiochemical parameters of the raw textile wastewater: color by 87.94%, BOD by 80.61%, COD by 80.96%, EC by 73.11%, fluoride by 81.15%, phosphate by 79.57%, sodium by 76.88%, and turbidity by 81.02%. Additionally, metal ions, including iron, were removed by 84.83%, while other metals, such as zinc, nickel, manganese, copper, lead, cadmium, total chromium, arsenic, barium, cobalt, and boron, were reduced to belowdetectable limits. Phytotoxicity tests confirmed the non-toxic nature of the treated effluent. Overall, the study concludes that Achromobacter xylosoxidans KUESCCHK-6 is a promising candidate for the bioremediation of textile industrial effluents, with potential for commercial application.

An effective biosurfactant producer and extremophiles bacteria, Bacillus cereus KH1, was isolated from textile effluent and the biosurfactant was produced using molasses as the sole carbon source. Growth parameters such as pH, temperature, salinity and concentration of molasses were optimised for decolourising the textile effluent with 24-h incubation. The biosurfactant property of B. cereus KH1 was evaluated based on haemolytic activity, oil displacement technique, drop-collapsing test and emulsification index. The results of the produced biosurfactant showed a positive reaction in haemolytic activity, oil displacement technique, drop-collapsing test and exhibiting a 67% emulsification index. The cell-free broth was stable in 40 °C pH 7, 7% salinity and 7% molasses. Thin-Layer Chromatography and Fourier Transform Infrared Spectroscopy analysis revealed that the biosurfactant was a lipopeptide with a yield 2.98 g L−1. These findings proved the synergistic action of B. cereus KH1 with lipopeptide biosurfactant may accelerated the decolourisation efficiency to 87%.