The real-time textile dyes wastewater contains hazardous and recalcitrant chemicals that are difficult to degrade by conventional methods. Such pollutants, when released without proper treatment into the environment, impact water quality and usage. Hence, the textile dye effluent is considered a severe environmental pollutant. It contains mixed contaminants like dyes, sodium bicarbonate, acetic acid. The physico-chemical treatment of these wastewaters produces a large amount of sludge and costly. Acceptance of technology by the industry mandates that it should be efficient, cost-effective and the treated water is safe for reuse. A sequential anaerobic-aerobic plant-microbe system with acclimatized microorganisms and vetiver plants, was evaluated at a pilot-scale on-site. At the end of the sequential process, decolorization and total aromatic amine (TAA) removal were 78.8% and 69.2% respectively. Analysis of the treated water at various stages using Fourier Transform Infrared (FTIR), High Performance Liquid Chromatography (HPLC)) Gas Chromatography-Mass Spectrometry (GC-MS) Liquid Chromatography-Mass Spectrometry (LC-MS) indicated that the dyes were decolourized and the aromatic amine intermediates formed were degraded to give aliphatic compounds. Scanning Electron Microscope (SEM) and Atomic Force Microscopy (AFM) analysis showed interaction of microbe with the roots of vetiver plants. Toxicity analysis with zebrafish indicated the removal of toxins and teratogens.

Biofilm-mediated bioremediation of xenobiotic pollutants is an environmental friendly biological technique. In this study, 36 out of 55 bacterial isolates developed biofilms in glass test tubes containing salt-optimized broth plus 2% glycerol (SOBG). Scanning electron microscopy, Fourier transform infrared (FTIR) spectroscopy, and Congo red- and Calcofluor binding results showed biofilm matrices contain proteins, curli, nanocellulose-rich polysaccharides, nucleic acids, lipids, and peptidoglycans. Several functional groups including –OH, N–H, C–H, CO, COO⁻, –NH₂, PO, C–O, and C–C were also predicted. By sequencing, ten novel biofilm-producing bacteria (BPB) were identified, including Exiguobacterium indicum ES31G, Kurthia gibsonii ES43G, Kluyvera cryocrescens ES45G, Cedecea lapagei ES48G, Enterobacter wuhouensis ES49G, Aeromonas caviae ES50G, Lysinibacillus sphaericus ES51G, Acinetobacter haemolyticus ES52G, Enterobacter soli ES53G, and Comamonas aquatica ES54G. The Direct Red (DR) 28 (a carcinogenic and mutagenic dye used in dyeing and biomedical processes) decolorization process was optimized in selected bacterial isolates. Under optimum conditions (SOBG medium, 75 mg L⁻¹ dye, pH 7, 28 °C, microaerophilic condition and within 72 h of incubation), five of the bacteria tested could decolorize 97.8% ± 0.56–99.7% ± 0.45 of DR 28 dye. Azoreductase and laccase enzymes responsible for biodegradation were produced under the optimum condition. UV–Vis spectral analysis revealed that the azo (−NN−) bond peak at 476 nm had almost disappeared in all of the decolorized samples. FTIR data revealed that the foremost characteristic peaks had either partly or entirely vanished or were malformed or stretched. The chemical oxygen demand decreased by 83.3–91.3% in the decolorized samples, while plant probiotic bacterial growth was indistinguishable in the biodegraded metabolites and the original dye. Furthermore, seed germination (%) was higher in the biodegraded metabolites than the parent dye. Thus, examined BPB could provide potential solutions for the bioremediation of industrial dyes in wastewater.

The widespread adoption of electrified carbon nanotube membranes (ECM) requires to better understand process effectiveness according to limiting phenomena of natural organic matters (NOMs). In this study, the influences of various NOM fractions were investigated on the oxidative degradation of Rhodamine B (RhB) in ECM. The results showed the decolorizing efficiencies of RhB in the presence of humic acid (HA) were still above 96%, while bovine serum albumin (BSA) reduced firstly and then increased the decolorizing efficiencies of RhB. The decolorizing efficiencies of RhB with alginate (AA) were over 98% at the first 15 min but decreased gradually to 76% after 150 min. These different performances of HA, BSA and AA were mainly due to their influences on the electrochemical reactivity characterization of ECM. ECM with the BSA depositing layer showed the highest exchange current density (j₀), while the AA depositing layer restrained electron-transfer activity of ECM. Cyclic voltammetry (CV) experiments showed that the partial electrooxidation of BSA would occur in ECM with its degradation product observed in the effluent. The variation of electrochemical reactivity characterization of ECM resulted into its electri-oxidation and electri-adsorption rates to be the largest with BSA, followed by AA and HA.

To enhance the dye removal efficiency by natural enzyme, horseradish peroxidase (HRP) was immobilized onto amine-functionalized superparamagnetic iron oxide and used as a biocatalyst for the oxidative degradation of acid black-HC dye. The anchored enzyme was characterized by vibrating sample magnetometry, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetry, scanning electron microscopy, Brunauer–Emmett–Teller and Barrett–Joyner–Halenda methods, nitrogen adsorption–desorption measurements, Zeta potential, energy dispersive X-ray spectroscopy, and transmission electron microscopy. The Michaelis constant values of free and immobilized HRP were determined to be 4.5 and 5 mM for hydrogen peroxide and 12.5 and 10 mM for guaiacol, respectively. Moreover, the maximum values of free and immobilized HRP were 2.4 and 2 U for H₂O₂, respectively, and 1.25 U for guaiacol. The immobilized enzyme was thermally stable up to 60°C, whereas the free peroxidase was stable only up to 40°C. In the catalytic experiment, the immobilized HRP exhibited superior catalytic activity compared with that of free HRP for the oxidative decolorization and removal of acid black-HC dye. The influence of experimental parameters such as the catalyst dosage, pH, H₂O₂ concentration, and temperature on the removal efficiency was investigated. The reaction followed second-order kinetics, and the thermodynamic activation parameters were determined.

The textile industry stands out as one of the largest consumers of water among the industrial sectors. Additionally, its effluent presents characteristics such as high load of chemical oxygen demand (COD), total organic carbon (TOC), suspended solids, color, turbidity, phenol, and salts, which require an efficient treatment of the wastewater produced. Among the several researches that have arisen focused on the treatment of textile effluents, electrocoagulation stands out. This method consists of an electrochemical process that generates its own coagulant by applying electric current to metal electrodes immersed in the solution. The electrodes used in the present study are metallic plates made of scrap iron. The objective of this work is to evaluate their application in an electrocoagulation process for the decolorization of real and synthetic effluents. The efficiency of the treatment was evaluated by applying it to a synthetic effluent containing commercial indigo blue dye and to a real effluent from the textile industry, assessing parameters such as color, turbidity, pH, electrical conductivity, COD, TOC, phenol, soluble iron, sludge generation, and electrode wear. The synthetic effluent obtained average color removal of 95%, 96% phenol, and low sludge production in 120 min of electrolysis. In the real effluent from the textile industry, an average color removal of 92%, 97% turbidity, 100% phenol, 65% TOC, and 49% COD in 90 min of electrolysis was obtained. The electrocoagulation process using scrap iron as electrodes proved to be efficient in removing the dye present in the real textile industry effluent, as well as in the synthetic effluent.

The effluents released from textile industries mainly consist of dyes, metals and other pollutants. Dyes often are discharged in wastewater streams causing adverse effect on the environment. To eliminate these harmful dyes, various techniques are emerging out of which nanotechnology is the most reliable and safer. Nanotechnology offers convincing applications in case of environmental and economic concerns. The bio-synthesis of nanoparticles has several advantages over conventional methods and approach towards environment concern as well. Biological method of nanoparticles synthesis is concluded to be the most promising and efficient in action. Bio-synthesised nanoparticles could be used for treatment and decolourisation of dyes in an efficient manner. This review comprises the study of number of bio-synthesised nanoparticles utilised for degradation of various dyes present as pollutants in wastewater. Bio-synthesised nanoparticles such as gold, silver, iron, cobalt, zinc, titanium and molybdenum used for degradation of various dyes have been discussed in this review.

In recent years, white rot fungi (WRFs) have received tremendous attention as a biotechnological tool for environmental pollution control. In order to systematically and comprehensively describe the progress, trends, and hotspots of WRF biotechnology in the field of environmental pollution control, the 3967 related publications from 2003 to 2020 were collected from Web of Science Core Collection database, and the bibliometric characteristics including publication output, country, institution, journal, author, citation frequency, h-index, and research focus were evaluated by using Excel 2007, CiteSpace V, and VOSviewer. The results indicated that the number of research publications increased rapidly before 2009, but after that, the number of publications fluctuated in a certain range. China and USA were the most productive countries and the most active country in international cooperation. In this field, most authors tend to cooperate within a small group. The journal and subject category with the largest number of publications are “International Biodeterioration & Biodegradation” and “Biotechnology Applied Microbiology”, respectively. The analysis of high-frequency keywords revealed that “laccase”, “biodegradation”, “decolorization”, and “Phanerochaete chrysosporium” were the most cited terms among all publications. The pretreatment of biomass waste, decolorization of dye wastewater, and bioremediation of polluted environment are the key research directions of WRF biotechnology. Finally, the frontier topics and active authors in this research field were identified using burst detection. We believe that this bibliometric study provides a comprehensive and systematic overview and promoted the future cooperative research and knowledge exchange in this field of WRF biotechnology for environmental applications.

In the present study, pyrophosphate (PP) was used to activate peroxymonosulfate (PMS) for acid orange 7 (AO7) removal under neutral pH conditions. The removal rate of AO7 (20 mg/L) was 84% within the reaction time with a rate constant value of 0.0165 min⁻¹ under optimum conditions. Additionally, the effects of the concentrations of PMS and PP in solutions with various pH values and the coexisting inorganic anions on AO7 removal were measured. In addition, the performance of phosphate (P(V)) on PMS activation was compared with that of phosphite (P(III)) species. In contrast to P(III), the concentration of P(V) showed a positive correlation with the efficiency of AO7 decolorization. PMS activation in different types of buffer solutions was also examined, and the results indicated that the decolorization efficiency of AO7 induced by PP addition, and the buffer solution also contributed to PMS self-decomposition. Singlet oxygen (¹O₂) might be the primary reactive oxygen species (ROS) in the PP/PMS system in which AO7 is decolorized at an initial pH of 7.06, as indicated by quenching experiments and electron spin resonance (ESR) tests. Therefore, PP/PMS systems may be promising technologies for removing organic contaminants, particularly for PP-rich electroplating wastewater.

The growing presences of conventional and emerging contaminants make the wastewater treatment increasingly difficult and expensive on a global scale. ZVI tends to be an expectable material for the detoxification of some difficult contaminants such as chlorinated solvents and nitroaromatics. In this work, together use with calcium carbonate (CaCO₃), which serves as a green supporter to ZVI and also direct participant toward the purification process, has been carried out by cogrinding to give a synergistic effect, particularly for treating multiple pollutants including both inorganic and organic compositions. Based on a set of analytical methods of XRD, FTIR, SEM, XPS, and other test methods, the activation mechanism of the ball milling process and the removal performances of the prepared composites were examined. The results prove that the mechanically activated calcium carbonate and ZVI composite samples exhibited extremely high removal capacity on a variety of pollutants contaminated water. The decolorization of azo dyes is mainly attributed to the breaking of chromogenic functional group nitrogen and nitrogen double bonds, and the removal mechanism of aromatic series occurs through a hydrogenation substitution reaction. As to the inorganic pollutant removals, besides the efficient heavy metal ion precipitations, phosphate and fluoride ions are co-precipitated through the formation of fluorapatite to achieve a simultaneous and synergistic removal effect. Under the optimal reaction conditions, the concentration of PO₄³⁻ is reduced from 250 to 0 mg/L, and that of F⁻ is reduced from 51.07 to 1.20 mg/L. The prepared composite sample of ZVI rand calcium carbonate allowed simultaneous removals of both inorganic and organic pollutants, simplifying the remediation process of complicated multiple contaminations.

In this study, the biosorption performance of Thamnidium elegans (T. elegans) immobilized on Phragmites australis (P. australis), a new biocomposite (TEPA), was examined for decolorization of water using batch and column mode tests. Various affecting experimental parameters such as pH, biocomposite amount, and stirring speed were examined and optimized by an experimental design. Regression analysis indicated that the findings of the Box-Behnken experimental design (BBD) optimization experiment closely match a quadratic model. ANOVA findings revealed that pH and TEPA amount affected Reactive Blue 49 (RB49) biosorption yield. Optimum experimental RB49 decolorization was achieved with the biosorption yield of 96.51% at the conditions of pH: 1.68, TEPA mass: 53.4 mg, stirring speed: 204 rpm, and contact time: 45 min. RB49 sorption onto TEPA was explained using the Elovich and the pseudo-second-order kinetic and the Freundlich isotherm models. The maximum RB49 sorption capacity was 140.36 mg g⁻¹ at defined optimum conditions. Unloaded and dye-loaded biocomposite sorbents were characterized by SEM and FTIR analysis. The isoelectric point of TEPA was found as pH 1.7 by the zeta potential measurements. Furthermore, the newly developed biocomposite sorbent indicated the promise in terms of decolorizing real wastewater without losing dye sorption ability. Saturation biosorption capacities in column mode were 104.58 and 70.98 mg g⁻¹ in dye solution and real wastewater samples, respectively. TEPA can be considered cost-effective, ecofriendly, and promising alternative adsorbent for decolorization of reactive dye contaminated wastewater, as shown by all the findings.