Fate and transformation of naphthylaminesulfonic azo dye reactive black 5 during wastewater treatment process

Pineapple wastewater as co-substrate in treating real alkaline, non-biodegradable textile wastewater using biogranulation technology

This study was to develop biogranules using a sequencing batch reactor (SBR) and to evaluate the effect of pineapple wastewater (PW) as a co-substrate for treating real textile wastewater (RTW). The biogranular system cycle was 24 h (2 stages of phase), with an anaerobic phase (17.8 h) followed by an aerobic phase (5.8 h) for every stage of the phase. The concentration of pineapple wastewater was the main factor studied in influencing COD and color removal efficiency. Pineapple wastewater with different concentrations (7, 5, 4, 3, and 0% v/v) makes a total volume of 3 L and causes the OLRs to vary from 2.90 to 0.23 kg COD/m3day. The system achieved 55% of average color removal and 88% of average COD removal at 7%v/v PW concentration during treatment. With the addition of PW, the removal increased significantly. The experiment on the treatment of RTW without any added nutrients proved the importance of co-substrate in dye degradation.

Antarctic yeasts: potential use in a biologic treatment of textile azo dyes

We investigated the dye-removal potential of a collection of 61 cold-adapted yeasts from the King George Island, Antarctica, on agar plates supplemented with 100 mg L-1 of several textile dyes; among which isolates 81% decolorized Reactive Black 5 (RB-5), with 56% decolorizing Reactive Orange 16, but only 26% doing so with Reactive Blue 19 and Acid Blue 74. Furthermore, we evaluated the ligninolytic potential using 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic-acid) diammonium salt-, 3,5-dimethoxy-4-hydroxybenzaldehydazine-, or manganese-supplemented plates but detected no activity, possibly due to a dye-removal mechanism involving reductases. The removal kinetics were studied in liquid medium supplemented with 100 mg L-1 of RB-5 in a selection of 9 yeasts. The highest volumetric-removal rates (η) were found for Candida sake 41E (4.14 mg L-1 h-1), Leucosporidium muscorum F20A (3.90 mg L-1 h-1), and Cystofilobasidium infirmominiatum F13E (3.90 mg L-1 h-1). Different UV-Vis spectra were obtained if the dye removal occurred by biodegradation or biosorption/bioaccumulation. L. muscorum F20A was selected to study the dye-removal mechanism of RB-5 and the effect of different chemical and environmental parameters on the process. Optimum dye-removal conditions were obtained with 10 g L-1 of glucose within an initial medium pH range of 5.0 to 6.0. Up to 700 mg L-1 of dye could be removed in 45 h. High-performance liquid chromatography profiles obtained were consistent with a biodegradation of the dye. Phytotoxicity was estimated by calculating the 50%-inhibition concentration (IC50) with Lactuca sativa L. seeds. These findings propose psychrophilic yeasts as a novel environmentally suitable alternative for the treatment of dye-industry wastewaters.

Microbe-assisted phytoremediation of environmental pollutants and energy recycling in sustainable agriculture

The perception of phytoremediation is efficiently utilized as an eco-friendly practice of green plants combating and cleaning up the stressed environment without harming it. The industrial revolution was followed by the green revolution which fulfilled the food demands of the growing population caused an increase in yield per unit area in crop production, but it also increased the use of synthetic fertilizers in agriculture. Globally, the intensive use of inorganic fertilizers in agriculture has led to serious health problems and irreversible environmental damage. Biofertilizers improve the growth of the plant and can be applied as an alternative to chemical/synthetic fertilizers. Cyanobacteria, bacteria, and fungi are known as some of the principal microbe groups used to produce biofertilizers that form symbiotic associations with plants. Microorganisms perform a key role in phosphate solubilization and mobilization, nitrogen fixation, nutrient management, biotic elicitors and probiotics, and pollution management (biodegradation agents), specifically bacteria which also help in atmospheric nitrogen fixation and are thus available for the growth of the plant. Management or biodegradation of hazardous chemical residues and heavy metals produced by a huge number of large-scale industries should be given primary importance to be transformed by various bacterial strains, fungi, algae. Currently, modern omics technologies such as metagenomic, transcriptomic, and proteomic are being used to develop strategies for studying the ecology of microorganisms, as well as their use in environmental monitoring and bioremediation. This review briefly discusses some of the major groups of microorganisms that can perform different functions responsible for plant health, crop production, phytoremediation and also focus on the omics techniques reportedly used in environmental monitoring to tackle the pollution load.

Catalytic ozonation of textile wastewater as a polishing step after industrial scale electrocoagulation

The main objective of this study was to develop the treatment system to change wastewater into a reliable source of recyclable water within the textile plant. Therefore, a highly polluted industrial wastewater originated in the dyeing of cotton was subjected to a multi-step treatment. The raw wastewater was characterized by the concentration of Reactive Black 5, the azo dye, as high as 842 mg/L, extreme alkalinity (pH 11.26) and salinity (NaCl concentration 52,290 mg/L). Correspondingly, the chemical oxygen demand (COD) was equal to 3440 mg/L and the total organic carbon (TOC) was 1790 mg/L in this wastewater. This salty, hardly degradable wastewater underwent the electrocoagulation (EC) on an industrial scale in the first step of the treatment. Although the industrial EC resulted in 84% of color removal in a very short time of 8 min, the wastewater was still characterized by an extremally high absorbance which corresponded to 100 mg/L of RB5. Moreover, EC resulted in the occurrence of burdensome by-products, of which one was identified in this study as an aniline derivative. The by-products contributed to high residual COD and TOC after EC (2120 mg/L and 1052 mg/L, respectively). Consequently, the catalytic ozonation was used by us as a second, the polishing, step of the treatment. The catalytic ozonation was found efficient in the removal of the residual color and colorless by-products. The wastewater after catalytic ozonation was colorless and the final COD and TOC decreased to 1283 and 695 mg/L, respectively. The average oxidation state (AOS), spectra analysis, and the toxicity assay showed catalytic ozonation efficient in the by-products oxidation. Consequently, the catalytic action of activated carbon (AC) was proved for the ozonation of textile wastewater. Ultimately, the recycling of purified wastewater into dyeing resulted in a very good color quality of textile samples (DE_CMC values below limiting value equal to 1.0).

Deciphering the mechanism of carbon sources inhibiting recolorization in the removal of refractory dye: Based on an untargeted LC-MS metabolomics approach

In this study, the biological decolorization of reactive black 5 (RB5) by Klebsiella sp. KL-1 in yeast extract (YE) medium was captured the recolorization after exposure to O₂, which induced a 15.82% reduction in decolorization efficiency. Similar result was also observed in YE + lactose medium, but not in YE + glucose/xylose media (groups YE + Glu/Xyl). Through biodegradation studies, several degradation intermediates without quinoid structure were produced in groups YE + Glu/Xyl and differential degradation pathways were deduced in diverse groups. Metabolomics analysis revealed significant variations in up-/down-regulated metabolites using RB5 and different carbon sources. Moreover, the underlying mechanism of recolorization inhibition was proposed. Elevated reducing power associated with variable metabolites (2-hydroxyhexadecanoic acid, 9(R)-HODE cholesteryl ester, linoleamide, oleamide) rendered additional reductive cleavage of C-N bond on naphthalene ring. This study provided a new orientation to inhibit recolorization and deepened the understanding of the molecular mechanism of carbon sources inhibiting recolorization in the removal of refractory dyes.

Industrial Textile Wastewater Ozone Treatment: Catalyst Selection

One of the recent trends in textile wastewater treatment has become catalytic ozonation. The necessity of effective color removal in a short treatment time is a standard during industrial implementation. At the same time, efficient chemical oxygen demand (COD), total organic carbon (TOC), and toxic by-product removal are highly expected. This study presents the results of a catalytic ozonation treatment. Three types of catalysts: a metal oxide (TiO2 as P25 by Degussa), activated carbon (nano-powder by Sigma, AC), and metal particles (platinum, 1% wt. supported on AC matrix by Sigma, Pt–AC) have been applied. The investigations were conducted for real industrial wastewater originated in textile dyeing with Reactive Black 5 dye (RB5). The experiments ran for the raw wastewater (without pretreatment), exposed blocking of the catalytic action by all used catalysts. The catalytic effect could be observed when catalytic ozonation was used as a polishing step after electrocoagulation (EC). Although the catalytic effect could be observe for all catalysts then, especially in the removal of colorless by-products, the AC was exposed as the most effective. This contributed to 35% and 40% of TOC and COD removal. While only 18% and 23% of TOC and COD were removed in the same process without AC. The decrease in toxicity was 30%. The results of the study revealed the complexity of the issue and resulted in an extensive discussion devoted to the basis of the catalytic activity of each catalyst.

Azo dyes decolorization under high alkalinity and salinity conditions by Halomonas sp. in batch and packed bed reactor

Biodecolorization and biodegradation of azo dyes are a challenge due to their recalcitrance and the characteristics of textile effluents. This study presents the use of Halomonas sp. in the decolorization of azo dyes Reactive Black 5 (RB5), Remazol Brilliant Violet 5R (RV5), and Reactive Orange 16 (RO16) under high alkalinity and salinity conditions. Firstly, the effect of air supply, pH, salinity and dye concentration was evaluated. Halomonas sp. was able to remove above 84% of all dyes in a wide range of pH (6-11) and salt concentrations (2-10%). The decolorization efficiency of RB5, RV5, and RO16 was found to be ≥ 90% after 24, 13 and 3 h, respectively, at 50 mg L^-1 of dyes. The process was monitored by HPLC-DAD, finding a reduction of dyes along the time. Further, Halomonas sp. was immobilized in volcanic rocks and used in a packed bed reactor for 72 days, achieving a removal rate of 3.48, 5.73, and 8.52 mg L^-1 h^-1, for RB5, RV5 and RO16, respectively, at 11.8 h. The study has confirmed the potential of Halomonas sp. to decolorize azo dyes under high salinity and alkalinity conditions and opened a scope for future research in the treatment of textile effluents.

Brine Recycling from Industrial Textile Wastewater Treated by Ozone. By-Products Accumulation. Part 1: Multi Recycling Loop

The “reactive” dyeing of textiles requires an application of low-molecular-weight salts (LMWS), such as NaCl or Na2SO4, as necessary auxiliary agents. LMWS acts only as a remediation factor and remains in the dyeing effluents constitute brine. The main goal of the presented study was to investigate the application of ozone technology for industrial textile wastewater highly polluted by LMWS. The study was divided into two parts. In Part 1, by-products accumulated during multi-recycling of the same wastewater was investigated. While Part 2 was devoted to the scaling up of ozonation process, Part 1 concerns the efficiency of textile wastewater ozonation carried out as a repeatable process. The sequence of wastewater treatment and textile dyeing was repeated four times in a closed loop using the same process water. Although the wastewater decolorization was efficient in the subsequent ozonation cycles, some adverse effects, such as an increase in chemical oxygen demand (COD) and self-buffering at pH 9.5–10.0, were suggested the accumulation of by-products. The preliminary detection of by-products by thin layer chromatography (TLC) revealed phenol and naphthol derivatives as the transformation products (TPs) of ozonation. Dyeing of cotton using purified wastewater (brine) resulted in very good DECMC color matching parameters (under 1.16), but only in the first recycling loop, and then the TPs affected the process.

Biodecolorization of recalcitrant dye as the sole sourceof nutrition using Curvularia clavata NZ2 and decolorization ability of its crude enzymes

Extensive use of recalcitrant azo dyes in textile and paper industries poses a direct threat to the environment due to the carcinogenicity of their degradation products. The aim of this study was to investigate the efficiency of Curvularia clavata NZ2 in decolorization of azo dyes. The ability of the fungus to decolorize azo dyes can be evaluated as an important outcome as existing effluent treatment is unable to remove the dyes effectively. C. clavata has the ability to decolorize Reactive Black 5 (RB5), Acid Orange 7 (AO7), and Congo Red azo dyes, utilizing these as sole sources of carbon and nitrogen. Ultraviolet-visible (UV-vis) spectroscopy and Fourier infrared spectroscopy (FTIR) analysis of the extracted RB5's metabolites along with desorption tests confirmed that the decolorization process occurred due to degradation and not merely by adsorption. Enzyme activities of extracellular enzymes such as carboxymethylcellulase (CMCase), xylanase, laccase, and manganese peroxidase (MnP) were also detected during the decolorization process. Toxicity expressed as inhibition of germination was reduced significantly in fungal-treated azo dye solution when compared with the control. The cultivation of C. clavata under sequential batch system also recorded a decolorization efficiency of above 90%. The crude enzyme secreted by C. clavata also showed excellent ability to decolorize RB5 solutions with concentrations of 100 ppm (88-92%) and 1000 ppm (70-77%) without redox mediator. This proved that extracellular enzymes produced by C. clavata played a major role in decolorization of RB5.