Reactive Blue 4 Decolorization under Mesophilic and Thermophilic Anaerobic Treatments

Anaerobic decolorization of anthraquinone dye represented by Reactive Blue 4 (RB4) was studied to evaluate the factors involved in dye-reducing behaviors such as dye concentration, co-substrate, treatment temperature, salt content, and dye-reducing microbial consortia. The experiment was conducted using digested sludge treated under mesophilic (35 °C) and thermophilic (55 °C) conditions. The results indicated that the thermophilic treatment gave higher potential for this dye decolorization compared with the mesophilic one. A reduced form of RB4 did not show an auto-oxidizing reaction but treated RB4 dye was shown in light yellow color, the intensity of which was related to the initial concentration of the dye used in the treatments. Starch, which showed similar decolorizing efficiency under thermophilic conditions, could be used as a co-substrate instead of glucose for the purpose of operating cost reduction. Due to the high content of salt contained in dye wastewater, the effect of salt (NaCl) was investigated. Results showed that decolorization could be accelerated with a concentration of NaCl lower than 200 mM, but the decolorization was inhibited by high concentrations of salt. The presence of RB4 inhibited methane productivity, while total organic carbon (TOC) reduction was similar to control, without dye addition. Increasing the temperature accelerated the decolorizing potential and TOC reduction. The evaluation of dye-reducing microbial consortia was done with acidogen and methanogen inhibitors which acidogenesis microorganism was dominant in RB4 decolorization.     

Key Factors Regarding Decolorization of Synthetic Anthraquinone and Azo Dyes

The factors affecting decolorization of anthraquinone dye represented by Reactive Blue 4 (RB4) and azo dye represented by Methyl Orange (MO) were studied in batch experiments under mesophilic (35 °C) and thermophilic (55 °C) anaerobic conditions. The results indicated differences in decolorization properties of the dyes with different chromophore structures. In abiotic conditions, MO could be decolorized by a physicochemical reaction when it was sterilized at 121 °C together with sludge cells or glucose. RB4 only showed absorption onto the cell mass. The presence of a redox mediator accelerated the decolorizing reaction when supplied together with glucose in the presence of sterilized sludge cells. In biotic conditions, the results indicated that the biological activity of microorganisms was an important factor in decolorization. The main factor involved in decolorization was the conversion of cosubstrate as electron donor, which reacted with dye as an electron acceptor in electron transfer. Redox mediators, anthraquinone-2-sulfonic acid, and anthraquinone could accelerate decolorization even if a small amount (0.2 mM) was applied. On the other hand, a high concentration of redox mediator (1.0 mM) had an inhibitory effect on decolorization especially under thermophilic conditions. In addition, the decolorization of dye was accelerated by increasing treatment temperature, as shown in biotic treatments. Based on these results, increasing the treatment temperature could be used to improve the decolorizing process of textile dye wastewater treatment, especially for recalcitrant dyes such as anthraquinone.     

Decolorization of Reactive Black 5 and Reactive Blue 4 Dyes in Microbial Fuel Cells

Microbial fuel cells (MFCs) have potential to treat industrial wastewater containing organic compounds and simultaneously generate power. Organic compounds include textile dyes with various chromophore groups, which can be decolorized reductively by microorganisms under anaerobic conditions. In the present study, we examined the decolorization of Reactive Black 5 (RB5) azo dye and Reactive Blue 4 (RBL4) anthraquinone dye under open circuit potential in MFCs with graphite plate and graphite felt electrodes and a microbial consortium originally derived from bovine rumen fluid. RB5 dye was more than 90% decolorized in 120, 165, and 225 min at 50, 100, and 200 mg L^?1 concentrations, respectively. RBL4 dye at 50 and 100 mg L^?1 took 225 and 300 min to decolorize, while 200 mg L^?1 RBL4 dye was not decolorized at all. Under closed circuit conditions, decolorization increased with decrease in external load, whereas current generation increased with external resistance. The results demonstrate that the reductive cleavage of the chromophore was more rapid with RB5 than with RBL4.     

Reductive decolorization of a textile reactive dyebath under methanogenic conditions

The objective of the present study was to assess the biological decolorization of an industrial, spent reactive dyebath and its three dye components (Reactive Blue 19 [RB 19], Reactive Blue 21 [RB 21], and Reactive Red 198 [RR 198]) under methanogenic conditions. Using a mixed, methanogenic culture, batch assays were performed to evaluate the rate and exten of color removal as well as any potential toxic effects. Overall, a high rate and extent of color removal (>10 mg/[L·h] and 88%, respectively) were observed in cultures amended with either RB19 (an anthraquinone dye) or spent dyebath at an initial dye concentration of 300 mg/L (expressed as RB 19 equivalent) and 30 g/L of NaCl. Inhibition of acidogenesis and, to a larger degree, of methanogenesis resulting in accumulation of volatile fatty acids was observed in both RB 19- and spent dyebath-amended cultures. RB 21 (a phthalocyanine dye) and RR 198 (an azo dye) tested at an initial concentration of 300 mg/L did not result in any significant inhibition of the mixed methanogenic culture. Based on results obtained with cultures amended with RB 19 with and without NaCl, as well as a control culture amended with 30 g/L of NaCl, salt was less inhibitory than either RB 19 or the dyebath. Therefore, the toxic effect of the spent dyebath is at least partially attributed to its major dye component RB 19 and NaCl. Further testing of the effect of RB 19 decolorization products on the methanogenic activity in the absence of NaCl demonstrated that these products are much less inhibitory than the parent dye. Although color removal occurred despite the severe culture inhibition, biological decolorization of full-strength reactive spent dyebaths using methanogenic cultures in a repetitive, closed-loop system is not deemed feasible. For this reason, a fermentative and halotolerant culture was developed and successfully used in our laboratory for the decolorization of industrial reactive dyebaths with 100 g/L of NaCl.     

Preliminary studies on bacterial decolorization of H-acid based azo dye-reactive black 5

A co-culture acclimatized to H-acid was used to degrade Reactive Black 5 (RB 5), a bis azo dye having central H-acid function. The effect of substrate concentration, pH and medium composition on the decolorization has been investigated. Decolorization was found independent of pH. Luria-Bertani broth favored decolorization over Yeast Extract; however further decolorization experiments have been conducted using Yeast Extract. The Michaelis-Menten Kinetic model is found to describe the dependence of specific decolorization rate on the RB 5 dye concentration.     

Dye fixation and decolourization of vinyl sulphone reactive dyes by using dicyanidiamide fixer in the presence of ferric chloride

A synthetic polymer was synthesized and used for the improvement of dyeing properties as well as decolorization of textile waste water. Two dyes were selected having anthraquinone based Remazol Blue R and azo based Remazol Red RB. It was observed that the synthetic polymer can be used as fixer for the fixation of dye by crosslinking between dye and fibre, which not only improves the dyeing properties but also helpful to coagulate the colour after dyeing. By single point method the concentrations of synthetic polymer were calculated in residual after dyeing. It was examined that the residual synthetic polymer is helpful in colour removal efficiency by coagulation of polymer with dye to form heavy molecules which settle down and decolorization occurred. Colour removal efficiency was found dependents on pH, concentration of synthetic polymer and inorganic coagulant.     

Fabrication of metal-organic framework Universitetet i Oslo-66 (UiO-66) and brown-rot fungus Gloeophyllum trabeum biocomposite (UiO-66@GT) and its application for reactive black 5 decolorization

Many various industries use synthetic dyes as their raw materials. These dyes have triggered environmental problems because of the occurring effluents, and one of the environmentally safe solutions for this problem is biodegradation through microorganisms. Reactive Black 5 (RB5) dye degradation was performed by utilizing a metal-organic framework Universitetet i Oslo-66 (UiO-66) and Gloeophyllum trabeum (GT) fungus biocomposite. The UiO-66@GT composite was fabricated by inoculating the fungal culture in flasks with the PDB medium that contained UiO-66. This biocomposite was applied to decolorize and degrade RB5 dye, while pure GT culture can decolorize about 36.47% in five days. The percentage of RB5 decolorization was shown to be increased with the addition of UiO-66; the composite could decolorize RB5 up to 72.55% after five days incubation period. Moreover, the optimum conditions for the 100% targeted rate of RB5 decolorization found by the Response Surface Methodology (RSM) are: initial RB5 concentration (72.54 mg L^-1), pH (6.53), and temperature (38.06 °C). Two novel metabolites from RB5 decolorization by the composite were detected based on LCMS-QTOF analysis and were used to propose a degradation pathway: 6-((1-amino-7,8-dihydroxy-6-sulfonaphthalen-2-yl) diazinyl) cyclohexa-2,4-dien-1-ide (m/z = 360) and 3,4-diamino-5,6-dihydroxy-1,2,7,8-tetrahydronaphthalene-2,7-disulfonic acid (m/z = 354).     

Kinetics of heterogeneous photocatalytic degradation of reactive dyes in an immobilized TiO2 photocatalytic reactor

The photocatalytic degradation of two reactive dyes has been investigated by UV/TiO2/H2O2 using an immobilized TiO2 photocatalytic reactor. Reactive Blue 8 (RB 8) and Reactive Blue 220 (RB 220) textile dyes were used as model compounds. Photocatalytic degradation processes were performed using a 5-L solution containing dyes. The initial concentrations of dyes were 50 mg/L. The radiation source was two 15 W UV-C lamps. A batch mode immersion photocatalytic reactor was utilized. UV-vis and ion chromatography (IC) analyses were employed to obtain the details of the photodegradation of the selected dyes. Colored synthetic waters were completely decolorized in relatively short time after UV irradiation in the presence of various concentrations of hydrogen peroxide. Formate, acetate, oxalate, and glyoxylate anions were detected as dominant aliphatic intermediates where they were further oxidized slowly to CO2. The UV/TiO2/H2O2 process was able to oxidize the dyes with partial mineralization of carbon, nitrogen, and sulfur heteroatoms into CO2, NO3-, and SO4(2-), respectively. Kinetics analysis indicates that the photocatalytic decolorization rates of the dye can be approximated by a pseudo-first-order model. The UV/TiO2/H2O2 process proved to be capable of decolorization and mineralization of the reactive dyes (RB 8 and RB 220).     

Salicylic-Acid-Mediated Enhanced Biological Treatment of Wastewater

Activated sludge represents a microbial community which is responsible for reduction in pollution load from wastewaters and whose performance depends upon the composition and the expression of degradative capacity. In the present study, the role of salicylic acid (SA) has been evaluated for acclimatization of activated sludge collected from a combined effluent treatment plant followed by analysis of the physiological performance and microbial community of the sludge. The biodegradative capacity of the acclimatized activated sludge was further evaluated for improvement in efficiency of chemical oxygen demand (COD) removal from wastewater samples collected from industries manufacturing bulk drugs and dyes and dye intermediates (wastewater 1) and from dye industry (wastewater 2). An increase in COD removal efficiency from 50% to 58% and from 78% to 82% was observed for wastewater 1 and wastewater 2, respectively. Microbial community analysis data showed selective enrichment and change in composition due to acclimatization by SA, with 50% of the clones showing sequence homology to unidentified and uncultured bacteria. This was demonstrated by analysis of partial 16S rDNA sequence data generated from dominating clones representing the metagenome which also showed the appearance of a unique population of clones after acclimatization, which was distinct from those obtained before acclimatization and clustered away from the dominating population.     

二氧化钛悬浆体系中八种染料的太阳光催化氧化降解

研究了二氧化钛悬浆体系中具有不同结构和不同取代基的八种染料化合物在太阳光作用下的降解过程。实验中测定了染料溶液的脱色速度、总有机碳去除率以及降解过程中部分无机离子的生成情况。结果显示,在此条件下,八种染料化合物均得到不同程度的降解。着重比较了染料分子在光催化降解过程中,不同取代基以及取代基的不同位置对染料分子降解及无机离子生成情况的影响,从而进一步揭示了染料分子的光催化降解机理。     

Aerobic Biodegradation Pathway for Remazol Orange by Pseudomonas aeruginosa

Removal of azo dyes from effluent generated by textile industries is rather difficult. Azo dyes represent a major class of synthetic colorants that are mutagenic and carcinogenic. Pseudomonas aeruginosa grew well in the presence of Remazol Orange (RO) and was able to decolorize and degrade it. In the present study, the decolorization and degradation efficiency using single culture P. aeruginosa with RO and textile wastewaters is studied. The elucidation of decolorization pathway for P. aeruginosa is of special interest. The degradation pathway and the metabolic products formed during the degradation were also predicted with the help of high performance liquid chromatography, Fourier transform infrared spectroscopy, and nuclear magnetic resonance spectroscopy analysis. The data show the cleavage of the azo dye RO to form both methyl metanilic acid and 4-aminobenzoic acid after decolorization and finally to oxidation forms benzoic acid, alkenes, aldehydes, and alkynes. The organism was able to decolorize the dye RO and wastewater effectively to the maximum of 82.4% and 62%, respectively.     

Kinetic studies of photoelectrocatalytic degradation of Ponceau 6R dye with ammonium persulfate

Kinetic degradation of Ponceau 6R dye using oxidation with ammonium persulfate (APS) as oxidant, and catalyzed by electro, photo, and photo-electro at pH 1.0 was investigated. Ammonium persulfate (APS) proved to be a better oxidant of dye with photoelectrocatalytic degradation (PECD). The influence of various pH of the solution on the efficiency of degradation of dye was investigated. The results were observed that the dye decolorization was enhanced using PECD at pH 2.0. The rate of degradation of dye with APS followed pseudo-first order kinetics in the dye concentration. Also, it can be seen that increasing the concentration of oxidant (APS) led to a higher rate of dye decolorization.     

Kinetics and products of ozonation of C.I. Reactive Red 195 in a semi-batch reactor

Textile wastewater shows great threats to the environment if not well pretreated before discharge. A promising technique, ozonation, was applied to remove the color in dye solutions containing C.I. Reactive Red 195 (RR195) in a semi-batch reactor. The decolorization of RR195 by the ozone process followed pseudo-first-order kinetics. Several factors which influenced the efficiency of decolorization were studied and the reaction rate constant (k) obtained with different operational parameters was compared. Our results showed that RR195 was more easily degraded in acidic than in alkaline conditions. The dyeing auxiliaries (sodium carbonate and sodium chloride) that acted as radical scavengers could enhance the decolorization process, and the ozonation time for total color removal lengthened if the initial dye concentration was higher. The analysis of the ozonation products was performed by liquid chromatography-tandem mass spectrometer and a possible degradation pathway was predicted according to the ozonation products and structure of RR195. Our results indicated that ozonation was effective in the color removal of dyes, but further treatment might be necessary since the ozonation products are high toxic.     

Textile Dye Biodecolorization by Manganese Peroxidase: A Review

Wastewater emissions from textile factories cause serious environmental problems. Manganese peroxidase (MnP) is an oxidoreductase with ligninolytic activity and is a promising biocatalyst for the biodegradation of hazardous environmental contaminants, and especially for dye wastewater decolorization. This article first summarizes the origin, crystal structure, and catalytic cycle of MnP, and then reviews the recent literature on its application to dye wastewater decolorization. In addition, the application of new technologies such as enzyme immobilization and genetic engineering that could improve the stability, durability, adaptability, and operating costs of the enzyme are highlighted. Finally, we discuss and propose future strategies to improve the performance of MnP-assisted dye decolorization in industrial applications.     

Development and Optimization of Single Filament Plasma Jets for Wastewater Decontamination

New efficient depollution techniques for water decontamination, purification and disinfection are being sought to replace those classic methods (chemical, filtration, ozonisation, photochemical reactions) that have deficiency for some substances. The use of plasma technologies, discharges in, or in contact with, wastewater are promising approaches for the decomposition of pollutants by highly oxidative radicals, charged particles, UV radiation, etc. produced by plasma. In the present study we report on the potential of radiofrequency single and multiple filamentary Dielectric Barrier Discharge (DBD) jets for the decolorization of methylene blue (MB) dye in water solutions. Optical emission spectroscopy (OES) investigations were performed for the characterization of plasma evolving in air, and in liquid. The decolorization process was monitored by absorption spectroscopy. We determined the decolorization time, according to a variety of external parameters. The key parameters for obtaining the maximum decolorization rate were identified as being the discharge tube diameter, tube nature (glass/ceramic), the injected power in the discharge, the type of reactive gas and the number of filamentary plasma jets.

     

Oxidative degradation of food dye E133 Brilliant Blue FCF Liquid chromatography-electrospray mass spectrometry identification of the degradation pathway

This paper is devoted to the evaluation of the degradation pathway of the E133 Brilliant Blue FCF (C.I. 42090) that is largely used in the food industry. The degradation is studied in oxidation conditions obtained by addition of potassium persulfate at different persulfate to dye molar ratios under natural sunlight irradiation. The degradation pathway of the dye passes through a species coloured in dark blue and then gives rise to uncoloured species. Due to the low volatility and the poor thermal stability of the dye, reversed-phase liquid chromatography associated to mass spectrometry and tandom mass spectrometry was employed to follow the kinetics of degradation and identify some intermediates. The identification of organic species still present in the decoloured dye and the value of COD obtained in these conditions show evidence that complete decolorization does not correspond to complete mineralisation. No direct information of toxicity is available for the uncoloured degradation products but the further formation of aromatic amines can not be excluded.     

Electrochemical decolorization of C.I. Acid Orange 3 in the presence of sodium chloride at iridium oxide electrode

The electrocatalytic degradation of C.I. Acid Orange 3 from simulated wastewater by indirect electrochemical oxidation using an IrO_x electrode was investigated. The effects of different operating parameters on the rate of dye decolorization were studied. The influences of mixing, electrolyte concentration, applied current, and initial dye concentration were examined. The change in dye concentration was followed by ultraviolet–visible spectroscopy, while the formation of reaction intermediates was established using high-performance liquid chromatography–mass spectrometry analysis. Ultraviolet–visible spectroscopy showed a decrease of the absorption peak at 374 nm during the electrolysis and the appearance of a new absorption maximum at 460 nm. The decolorization reaction can be followed only at 460 nm. Four intermediate products (two mono- and two dichlorinated) were detected. At the end of the study, a phytotoxicity assay was performed to determine the effectiveness of the applied method. The results showed that the applied electrochemical treatment of C.I. Acid Orange 3 leads to a decrease in phytotoxicity from 53 to 28%.     

Blue dye degradation in an aqueous medium by a combined photocatalytic and bacterial biodegradation process

This paper aimed at implementing a treatment system for polluted water with textile dyes, starting with a photocatalytic decomposition process using sunlight as a source of energy and continuing with a bacterial biodegradation process, in order to reach degradation percentages higher than those obtained using only one of the processes mentioned above. When water treatment with the dye in the combined system was over, an acute ecotoxicity test was performed to make sure that toxic metabolites were not produced due to biodegradation. Solophenyl Blue azoic dye, and Erionyl Blue and Terasil Blue anthraquinone dye-colored solutions were treated with the Pd/Al ₈₀ Ce ₁₀ Zr ₁₀ catalyst in a solar collector for the photocatalytic process. On the other hand, the waste dye, which was obtained from photocatalysis with a bacterial consortium from polluted areas by metals and hydrocarbons in aerobic conditions, was inoculated for biodegradation. Biodegradation was obtained for the dyes after both processes as 90.91% for the Solophenyl Blue azoic dye, and 87.80% and 87.94%, respectively, for the Erionyl Blue and Terasil Blue anthraquinone dyes. After the degradation processes, it was proven, via an ecotoxicity test with Daphnia magna , that toxic metabolites had not been produced.     

Decolorization and Biodegradation of Rubine GFL by Microbial Consortium GG-BL in Sequential Aerobic/Microaerophilic Process

This study represents the development of a new batch method by consortium GG-BL using two microbial cultures viz., Galactomyces geotrichum MTCC 1360 and Brevibacillus laterosporus MTCC 2298, by varying environmental conditions for the decolorization and biodegradation of Rubine GFL. Consortium was found to give better decolorization and degradation of Rubine GFL as compared to the individual microorganism at aerobic/microaerophilic process. The consortial metabolic activity of these strains lead to 100% decolorization of Rubine GFL (50?mg/L) within 30?h with significant reduction in chemical oxygen demand (79%) and total organic carbon (68%). Induction in the activities of laccase, veratryl alcohol oxidase, tyrosinase, azo reductase, and riboflavin reductase suggested their role in the decolorization process. Nondenaturing polyacrylamide gel electrophoresis analysis showed differential induction pattern of oxidoreductive enzymes during decolorization of the dye at different incubation temperatures. The degradation of Rubine GFL into different metabolites by individual organism and in consortium was confirmed using high performance thin layer chromatography, high performance liquid chromatography, Fourier transform infrared spectroscopy, and gas chromatography-mass spectroscopy analysis. Phytotoxicity studies revealed nontoxic nature of the metabolites of Rubine GFL.     

TiO2/柚子皮生物质活性炭复合材料的制备和吸附光降解性研究

本文以自制柚子皮生物质活性炭为原料,采用凝胶-溶胶法合成TiO2/柚子皮生物质活性炭复合材料(TiO2/BAC)。对复合材料进行SEM、FTIR、XRD等表征,并研究该复合材料对中性红、亚甲基蓝染料及甲醛的吸附降解性能。结果表明,在复合材料中柚子皮生物质活性炭的添加量为7 g、预吸附时间为2 h时,对染料具有最佳的吸附降解效果,复合材料在循环使用5次后对染料的吸附降解率仍达到了80 %以上。当活性炭的添加量为6 g、复合材料的添加量为2 g时,复合材料对甲醛的吸附降解达到最大,可达61%。表明该复合材料对中性红、亚甲基蓝染料及甲醛具有良好的吸附降解效果,有望用于废水染料的去除和家居甲醛净化。