Titania nanowires as substrates for sensing and photocatalysis of common textile industry effluents

Sensing and photocatalysis of textile industry effluents such as dyes using mesoporous anatase titania nanowires are discussed here.Spectroscopic investigations show that the titania nanowires preferentially sense cationic (e.g. Methylene Blue, Rhodamine B) over anionic (e.g. Orange G, Remazol Brilliant Blue R) dyes. The adsorbed dye concentration on titania nanowires increased with increase in nanowire dimensions and dye solution pH. Electrochemical sensing directly corroborated spectroscopic findings. Electrochemical detection sensitivity for Methylene Blue increased by more than two times in magnitude with tripling of nanowire average length. Photodegradation of Methylene Blue using titania nanowires is also more efficient than the commercial P25-TiO2 nanopowders. Keeping illumination protocol and observation times constant, the Methylene Blue concentration in solution decreased by only 50% in case of P25-TiO2 nanoparticles compared to a 100% decrease for titania nanowires. Photodegradation was also found to be function of exposure times and dye solution pH.Excellent sensing ability and photocatalytic activity of the titania nanowires is attributed to increased effective reaction area of the controlled nanostructured morphology. (C) 2010 Elsevier B.V. All rights reserved.

An introduction to textile bleaching /

Printed in Great Britain.

Recent insights into microbial catalases: isolation, production and purification

Catalase, an oxidoreductase enzyme, works as a detoxification system inside living cells against reactive oxygen species formed as a by-product of different metabolic reactions. The enzyme is found in a wide range of aerobic and anaerobic organisms. Catalase has also been employed in various analytical and diagnostic methods in the form of biosensors and biomarkers in addition to its other applications in textile, paper, food and pharmaceutical industries. New applications for catalases are constantly emerging thanks to their high turnover rate, distinct evolutionary origin, relatively simple and well-defined reaction mechanisms. The following review provides comprehensive information on isolation, production and purification of catalases with different techniques from various microbial sources along with their types, structure, mechanism of action and applications.

Decolorization of textile dyes by cyanobacteria

Cyanobacteria are widely distributed in the environment and may be an effective and economic alternative for removing dyes from textile industry effluents. The present work investigated the potential of six cyanobacterial strains in decolorizing eleven types of textile dyes. The maximum absorbance of each dye was verified using a spectrophotometer. Mass spectrometry was used to verify the removal and possible degradation of dyes by the cyanobacteria. The results showed that all of the evaluated cyanobacteria were able to remove indigo, palanil yellow, indanthrene yellow, indanthrene blue, dispersol blue, indanthrene red and dispersol red by more than 50%. The Brazilian isolate Phormidium sp. CENA135 was able to decolorize and completely remove indigo blue BANN 30. This study confirmed the capacity of cyanobacteria to decolorize and possibly to structurally degrade different textile dyes, suggesting the possibility of their application in bioremediation studies.

Tracking and identifying wastewater toxicants and assessing their biodegradation products

Screening of wastewater effluents from municipal and industrial wastewater treatment plants with biotests showed that the treated wastewater effluents possess only minor acute toxic properties towards whole organisms (e.g. bacteria, algae, daphnia), if any. In vitro tests (sub-mitochondrial membranes and fish hepatocytes) were generally more susceptible to the effluents. Most of the effluents indicated the presence of hormonally active compounds, as the production of vitellogenin, an egg yolk precursor protein, was induced in fish hepatocytes exposed to wastewater. In addition, indications of slight genotoxic potential was found in one effluent concentrate with a recombinant bacteria test. Reverse electron transport (RET) of mitochondrial membranes was used as a model test to conduct effluent assessment followed by toxicant characterisations and identifications. Using a modified U.S. EPA Toxicity Identification Evaluation Phase I scheme and additional case-specific methods, the main compound in a pulp and paper mill effluent causing RET inhibition was characterised to be an organic, relatively hydrophilic high molecular weight (HMW) compound. The toxicant could be verified as HMW lignin by structural analyses using nuclear magnetic resonance. In the confirmation step commercial and in-house extracted lignin products were used. The possible toxicity related structures were characterised by statistical analysis of the chemical breakdown structures of laboratory-scale pulping and bleaching effluents and the toxicities of these effluents. Finally, the biological degradation of the identified toxicant and other wastewater constituents was evaluated using bioassays in combination with chemical analyses. Biological methods have not been used routinely in establishing effluent discharge limits in Finland. However, the biological effects observed in this study could not have been predicted using only routine physical and chemical effluent monitoring parameters. Therefore chemical parameters cannot be considered to be sufficient in controlling effluent discharges especially in case of unknown, possibly bioaccumulative, compounds that may be present in small concentrations and may cause chronic effects.

Simultaneous biosorption of methylene blue and trivalent chromium onto olive stone

In this work, olive stone (OS) was utilized to investigate its capacity as biosorbent for methylene blue (MB) and Cr(III), which are usually present in textile industry effluents. Equilibrium and kinetic experiments were performed in batch experiments. The biosorption process followed pseudo-second-order kinetics. The equilibrium data were fitted with several models, but Langmuir and Sips models best reproduced the experimental results. Maximum biosorption capacities were 3.296 mg/g (0.0116 mmol/g) and 4.990 mg/g (0.0960 mmol/g) for MB and Cr(III), respectively. Several operation variables, such as
biosorbent mass, flow rate, and initial concentration on the removal of dye and metal, were evaluated in column system. The removal efficiency improved as OS mass increased and decreased when flow rate and initial concentration increased. Also, MB uptake was substantially decreased by increasing the initial concentration of Cr(III), ranging from 6.09 to 2.75 mg/g. These results show that the presence of Cr(III) significantly modifies the biosorption capacity of MB by the OS. These results suggest that OS is a potential low-cost food industry waste for textile industry wastewater treatment.

Production and Characterization of Endocylanase from Bacillus Pumilus Using Solidstate Fermentation and its Application in 'Paper Pulp Processing

In the present studies it is clear that Bacillus pumilus xylanase is having the characteristic suited for an industrial enzyme (xylanases that are active and stable at elevated temperatures and alkaline pH are needed). SSF production of xylanases and its application appears to be an innovative technology where the fermented substrate is the enzyme source that is used directly in the bleaching process without a prior downstream processing. The direct use of SSF enzymes in bleaching is a relatively new biobleaching approach. This can certainly benefit the bleaching process to lower the xylanase production costs and improve the economics and viability of the biobleaching technology. The application of enzymes to the bleaching process has been considered as an environmentally friendly approach that can reduce the negative impact on the environment exerted by the use of chlorine-based bleaching agents. It has been demonstrated that pretreatment of kraft pulp with xylanase prior to bleaching (biobleaching) can facilitate subsequent removal of lignin by bleaching chemicals, thereby, reducing the demand for elemental chlorine or improving final paper brightness. Using this xylanase pre-treatment, has resulted in an increased of brightness (8.5 Unit) when compared to non-enzymatic treated bleached pulp prepared using identical conditions. Reduction of the consumption of active chlorine can be achieved which results in a decrease in the toxicity, colour, chloride and absorbable organic halogen (AOX) levels of bleaching effluents. The xylanase treatment improves drainage, strength properties and the fragility of pulps, and also increases the brightness of pulps. This positive result shows that enzyme pre-treatment facilitates the removal of chromophore fragments of pulp there by making the process more environment friendly

Advanced oxidation process H2O2/UV combined with anaerobic digestion to remove chlorinated organics from bleached kraft pulp mill wastewater

This study investigated the application of an advanced oxidation process combining hydrogen peroxide with ultraviolet radiation (H2O2/UV) to remove recalcitrant compounds from Kraft bleaching effluent. Anaerobic pre-treatment was performed to remove easily degraded organics using a horizontal-flow anaerobic immobilized biomass (HAIB) reactor. Bleaching plant effluent was treated in the HAIB reactor processed over 19 h of hydraulic retention time (HRT), reaching the expected removal efficiencies for COD (61 +/- 3%), TOC (69 +/- 9%), BOD5 (90 +/- 5%) and AOX (55 +/- 14%). However, the anaerobic treatment did not achieve acceptable removal of UV254 compounds. Furthermore, there was an increase of lignin, measured as total phenols. The H2O2/UV post-treatment provided a wide range of removal efficiencies depending on the dosage of hydrogen peroxide and UV irradiation: COD ranged from 0 to 11%, UV254 from 16 to 35%, lignin from 0 to 29% and AOX from 23 to 54%. All peroxide dosages applied in this work promoted an increase in the BOD5/COD ratio of the wastewater. The experiments demonstrate the technical feasibility of using H2O2/UV for post-treatment of bleaching effluents submitted to anaerobic pre-treatment.

The role of cytochromes P450 and peroxidases in the detoxification of sulphonated anthraquinones by rhubarb and common sorrel plants cultivated under hydroponic conditions

Sulphonated anthraquinones are precursors of many synthetic dyes and pigments, recalcitrant to biodegradation and thus not eliminated by classical wastewater treatments. In the development of a phytotreatment to remove sulphonated aromatic compounds from dye and textile industrial effluents, it has been shown that rhubarb (Rheum rabarbarum) and common sorrel (Rumex acetosa) are the most efficient plants. Both species, producing natural anthraquinones, not only accumulate, but also transform these xenobiotic chemicals. Even if the precise biochemical mechanisms involved in the detoxification of sulphonated anthraquinones are not yet understood, they probably have cross talks with secondary metabolism, redox processes and plant energy metabolism. The aim of the present study was to investigate the possible roles of cytochrome P450 monooxygenases and peroxidases in the detoxification of several sulphonated anthraquinones. Both plant species were cultivated in a greenhouse under hydroponic conditions, with or without sulphonated anthraquinones. Plants were harvested at different times and either microsomal or cytosolic fractions were prepared. The monooxygenase activity of cytochromes P450 toward several sulphonated anthraquinones was tested using a new method based on the fluorimetric detection of oxygen consumed during cytochromes P450-catalysed reactions. The activity of cytosolic peroxidases was measured by spectrophotometry, using guaiacol as a substrate. A significant activity of cytochromes P450 was detected in rhubarb leaves, while no (rhizome) or low (petioles and roots) activity was found in other parts of the plants. An induction of this enzyme was observed at the beginning of the exposition to sulphonated anthraquinones. The results also indicated that cytochromes P450 were able to accept as substrate the five sulphonated anthraquinones, with a higher activity toward AQ-2,6-SS (0.706 nkat/mg protein) and AQ-2-S (0.720 nkat/mg protein). An activity of the cytochromes P450 was also found in the leaves of common sorrel (1.212 nkat/mg protein (AQ-2,6-SS)), but no induction of the activity occurred after the exposition to the pollutant. The activity of peroxidases increased when rhubarb was cultivated in the presence of the five sulphonated anthraquinones (0.857 nkat/mg protein). Peroxidase activity was also detected in the leaves of the common sorrel (0.055 nkat/mg protein), but in this plant, no significant difference was found between plants cultivated with and without sulphonated anthraquinones. Results indicated that the activity of cytochromes P450 and peroxidases increased in rhubarb in the presence of sulphonated anthraquinones and were involved in their detoxification mechanisms. These results suggest the existence in rhubarb and common sorrel of specific mechanisms involved in the metabolism of sulphonated anthraquinones. Further investigation should be performed to find the next steps of this detoxification pathway. Besides these promising results for the phytotreatment of sulphonated anthraquinones, it will be of high interest to develop and test, at small scale, an experimental wastewater treatment system to determine its efficiency. On the other hand, these results reinforce the idea that natural biodiversity should be better studied to use the most appropriate species for the phytotreatment of a specific pollutant.

Bioremediation of Dyes in Textile Effluents by Aspergillus oryzae

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Decolorization of textile dye by Candida albicans isolated from industrial effluents

The aim of the present work was to observe microbial decolorization and biodegradation of the Direct Violet 51 azo dye by Candida albicans isolated from industrial effluents and study the metabolites formed after degradation. C. albicans was used in the removal of the dye in order to further biosorption and biodegradation at different pH values in aqueous solutions. A comparative study of biodegradation analysis was carried out using UV-vis and FTIR spectroscopy, which revealed significant changes in peak positions when compared to the dye spectrum. Theses changes in dye structure appeared after 72 h at pH 2.50; after 240 h at pH 4.50; and after 280 h at pH 6.50, indicating the different by-products formed during the biodegradation process. Hence, the yeast C. albicans was able to remove the color substance, demonstrating a potential enzymatic capacity to modify the chemical structure of pigments found in industrial effluents.

The Production of Ligninolytic Enzymes by Marine-Derived Basidiomycetes and Their Biotechnological Potential in the Biodegradation of Recalcitrant Pollutants and the Treatment of Textile Effluents

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Bioremediation of direct dyes in simulated textile effluents by a paramorphogenic form of Aspergillus oryzae

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Bioremediation of direct dyes in simulated textile effluents by paramorphogenic form of Aspergillus oryzae

Azo dyes are extensively used for coloring textiles, paper, food, leather, drink, pharmaceutical products, cosmetics and inks. The textile industry consumes the largest amount of azo dyes, and it is estimated that approximately 10 - 15% of dyes used for coloring textiles might be lost in waste streams. Almost all azo dyes are synthetic and resist biodegradation, however, they can be readly reduced by a number of chemical and biological reducing systems. Biological treatment is advantageous over physical and chemical method as result of its low cost and little disturbance to the environment. This research focuses on the utilization of Aspergillus oryzae, to remove some kinds of azo dyes from aqueous solutions. The fungi, physically induced in its paramorphogenic form (called, pellets), were used in the dyes biosorption studies with both non autoclave and autoclaved hyphas, at differents pH values. Thus the goals are the removal of dyes by biosorption and the decrease of its toxicity.

Electrolysis applied for simulated textile effluents degradation containing acid red 151 and acid blue 40

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)