Decolorization and bio degradation metabolism of azo dyes by Pseudomonas S-42

A bacterial strain was isolated from activated sludge and has been identified as Pseudomonas sp. S-42 capable of decolorizing azo dyes such as Diamira Brilliant Orange RR (DBO-RR), Direct Brown M (DBM), Eriochrome Brown R (EBR) and so on. The growing cells, intact cells, cell-free extract and purified enzyme of strain S-42 could decolorize azo dyes under similar conditions at the optimum pH 7.0 and temperature of 37℃. The efficiencies of decolorization for DBO-RR, DBM, EBR with intact cells stood more than 90%. When the cell concentration was 15mg (wet)/ml and the reaction time was 5 hours, the decolorizing activities of intact cells for above three azo dyes were 1.75, 2.4, 0.95 μg dye/mg cell, respectively. Cell-free extract and purified enzyme belonged to azoreductase with molecular weight about 34000±2000 and Vmax and Km values for DBO-RR of 13μmol/mg protein/nun and 54μmol, respectively. The results from the detection of the biodegradation products of DBO-RR by spectrophotometric and NaNO2 reaction methods showed that the biodegradation of azo dyes was initiated by the reducing cleavage of azo bonds. The biodegradation metabolism path for DBO-RR by Psued. S-42 was hypothesized.

Comparison of decolorization of reactive azo dyes by microorganisms isolated from various sources

Azo dyes are among the oldest man made chemicals and they are still widely used in the textile, printing and the food industries. About 10%-15% of the total dyes used in the industry is released into the environment during the manufacturing and usage. Some dyes and some of their N substituted aromatic bio transformation products are toxic and/or carcinogenic and therefore these dyes are considered to be environmental pollutants and health hazards. These azo dyes are degraded by physico chemical and biological methods. Of these, biological methods are considered to be the most economical and efficient. In this work, attempts were made to degrade these dyes aerobically. The organisms which were efficient in degrading the following azo dyes Red RB, Remazol Red, Remazol Blue, Remazol Violet, Remazol Yellow, Golden Yellow, Remazol Orange, Remazol Black were isolated from three different sources viz., wastewater treatment plant, paper mill effluent treatment plant and tannery wastewater treatment plant. The efficiency of azo dye degradation by mixed cultures from each source was analyzed. It was found that mixed cultures from tannery treatment plant worked efficiently in decolorizing Remazol Red, Remazol Orange, Remazol Blue and Remazol Violet, while mixed cultures from the paper mill effluent worked efficiently in decolorizing Red RB, Golden Yellow and Remazol Yellow. The mixed cultures from wastewater treatment plant efficiently decolorized Remazol Black.

Biodegradation of azo dyes by genetically engineered azoreductase

A azoreductase gene with 537 bp was obtained by PCR amplification from Rhodobacter sphaeroides AS1 1737 The enzyme, with a molecular weight of 18 7 kD, was efficiently expressed in Escherichia coli and its biodegradation characteristics for azo dyes were investigated. Furthermore, the reaction kinetics and mechanism of azo dyes catalyzed by the genetically engineered azoreductase were studied in detail. The presence of a hydrazo-intermediate was identified, which provided a convincing evidence for the assumption that azo dyes were degraded via an incomplete reduction stage.

Effect of Quinoid Mediators on the Decolorization of Azo Dyes by the Strain CD-2

In the present study, the effects of various quinone compounds on the decolorization rates of azo dyes by the E. coli strain CD-2 were investigated. The results showed that Lawsone was the most effective redox mediator. The optimum concentration for Lawsone is 0.1 mmol/L. The effects of physic-chemical parameters on the Methyl Orange degradation by the strain were determined. The results indicated that, in the quinone mediated decolorization system, strain CD-2 exhibited a good degradation ability in the range of pH from 4 to 9, temperature from 20°C to 50°C and salinity from 1% to 6%. With Lawsone as a redox mediator, a broad spectrum of azo dyes with different structures could be decolorized by the strain. All the results showed that the addition of a redox mediator can be valuable for treating dye-colored wastewaters.

Anaerobic Biodecolorization of Remazol Dye by a Strain of Enterobacter Isolated from Textile Sludge

Enterobacter GY-1 gained from a lab scale anaerobic-anoxic-aerobic (A2O) process treating textile effluent can effectively decolorize remazol dye. Under anaerobic condition, 91% of this remazol dye is decolorized, which is much higher than under aerobic condition. The optimum pH is 7 and the optimum temperature is 35 ℃ for the remazol dye decolorization by GY-1. Anthraquinone dyes and monoazo dyes are decolorized more efficiently by GY-1 than other dyes tested decolorized. GY-1 can not decolorize the remazol dye when it is the sole carbon source. Microbial cometabolism and decolorization of dye take place in the presence of some other carbon source called cometabolic substrate. The cometabolic substrate can be glucose, starch, peptone, beef extract, etc. The change of molecular structure of the dye before and after decolorized by GY-1 is studied by UV-Vis absorption spectrum. The results indicate that its molecular structure is changed evidently.

Screening and Identification of a Highly Effective Azo Dye-degrading Strain

In this study, strain tsl-2, which could effectively degrade azo dye amaranth, was isolated from activated sludge in the sewage treatment pool of a print- ing and dyeing mill in Liaocheng City, Shandong Province. Based on morphological characteristics, physiological and biochemical properties and 16S rDNA se- quence analysis, the isolated strain was identified preliminarily as Leucobacter komagatae. The decolorization of strain tsl-2 was investigated under static culture conditions. The results showed that strain tsl-2 exhibited the highest decolorization rate when initial concentration of amaranth was 50 rag/L, and the maximum de- colorization concentration was 1 250 mg/L. After decolorization under optimal conditions for 14 h, the decolorization rate of amaranth reached above 95%. This study provided the basis for further optimization of azoreductase production conditions.

Electrochemical and Photoelectrochemical Decoloration of Amaranth Dye Azo Using Composited Dimensional Stable Anodes

In this paper we report the results of our experimental work conducted to decoloration of a well-known highly toxic Amaranth dye by electrochemical and photoelectrochemical methods. Throughout this investigation were used two different Dimensional Stable Anode (DSA) electrodes, namely, IrO2-Ru2O-SnO2-TiO2/Ti and Ru2O-SnO2-TiO2/Ti. The experimental results show that IrO2-Ru2O-SnO2-TiO2/Ti electrode has higher performance on amaranth decoloration than Ru2O-SnO2-TiO2/Ti electrode, but with the disadvantage of higher energy consumption. For higher degradation of Amaranth dye with both DSA electrodes, the process was carried out via photoelectrochemical method. Our experimental results clearly shown the decrease in absorbance of all UV-Vis peaks due to the mineralization of the azo dye;also, it was noteworthy photoelectrochemical process consumes less energy under the same experimental conditions than electrochemical process. The IrO2-Ru2O-SnO2-TiO2/Ti electrode reaches a higher degradation degree of Amaranth solutions than Ru2O-SnO2-TiO2/Ti electrode using a photoelectrochemical technique.

Effects of glucose on the decolorization of Reactive Black 5 by yeast isolates

The cometabolic roles of glucose were investigated in decolorization of an azo dye, Reactive Black 5, by yeast isolates, Debaryomyces polymorphus and Candida tropicalis. The results indicated that the dye degradation by the two yeasts was highly associated with the yeast growth process and glucose presence in the medium. Color removal of 200 mg dye/L was increased from 76.4% to 92.7% within 60 h to 100% within 18-24 h with the increase of glucose from 5 to 10 g/L, although the activity of manganese dependent peroxidase （MnP） decreased by 2-8 times in this case. Hydrogen peroxide of 233.3 μg/L was detected in 6 h in D. polymorphus culture. The cometabolic functions of glucose and hydrogen peroxide could be also confirmed by the further color removals of 95.8% or 78,9% in the second cycle of decolorization tests in which 7 g glucose/L or 250 μg H202/L was superadded respectively together with 200 mg dye/L.

Decolorization of Anthraquinone dye by Rhodopseudomonas XL-1

Rhodopseudomonas XL 1 gained from textile wastewater can effectively decolorize anthraquinone dye. Under anaerobic condition, 93 percent of the anthraquinone dye is decolorized , which is higher than that under aerobic condition. The optimum pH is 6～9 and the optimum temperature is 20～40℃ for the anthraquinone dye decolorization by XL 1 . XL 1 can not decolorize the anthraquinone dye when it is the sole carbon source. Microbial cometabolism and decolorization of the dye take place in the presence of some other carbon source(0.2～0.4g/100ml)called cometabolic substrate. The cometabolic substrate can be peptone, glucose, sodium acetate, beef extract, amylum, etc. The change of molecular structure of the dye before and after decolorized by XL 1 is studied by UV Vis absorption spectrum. The results indicate that its molecular structure is changed evidently.

Microwave-assisted Fenton-like decolorization of methyl orange solution using chromium compounds

Azo dyes discharged in the environment are persistent organic pollutants (POPs),which are very difficult to remove. We developed a microwave-assisted Fenton-like process to degrade methyl orange (MO),an azo dye,with hydrogen peroxide (H2O2) catalyzed by chromium compounds coexisting with MO in the solution. Comparison between the Cr(Ⅲ)-H2O2 and Cr(VI)-H2O2 systems shows that Cr(VI) has a stronger and more stable catalytical activity than Cr(Ⅲ),and Cr(Ⅲ) is more susceptible to a change in the acidity or alkalinity of the reaction system. With a Cr(VI) concentration of 10 mmol L-1 or a Cr(Ⅲ) concentration of 12 mmol L?1 in the solution under the microwave irradiation of a power larger than 300 W for 3 min,10 mmol L-1 H2O2 can degrade more than 95% of 1 000 mg L-1 methyl orange; when the microwave power is increased to 700 W,the same amount of H2O2 can degrade all methyl orange in the solution with the same amount of Cr(VI) catalyst. Ultraviolet-visible spectrography indicates the cleavage of the azo bond in methyl orange after treatment,suggesting the potential of this Fenton-like process to degrade azo dye POPs. Reusing waste chromium compounds coexisting with dyestuff in wastewater to catalyze the degradation of azo dyes could be a cost-effective technique for azo dyes and chromate manufacturers and/or users to treat their wastewater and prevent POPs from endangering the environment. This is of particular importance to controlling the water quality of the Three Gorges Reservoir.

Nitrogen-doped pyrogenic carbonaceous matter facilitates azo dye decolorization by sulfide: The important role of graphitic nitrogen

Pyrogenic carbonaceous matter(PCM) catalyzes azo dye decolorization by sulfide, but the nitrogen doping catalytic mechanisms are poorly understood. In this study, we found that stagnate time of azo dye methyl orange(MO) decolorization was reduced to 0.54-18.28 min in the presence of various nitrogen-doped graphenes(NGs), remarkably lower compared to graphene itself. Particularly, graphitic nitrogen played a critical role in NGs-catalyzed MO decolorization by sulfide. Gas chromatography-mass spectrometry and in-situ surface Raman analysis demonstrated that doping nitrogen, especially graphite one facilitated reactive intermediate polysulfides formation. This is attributed to the improved electron conductivity through graphitic nitrogen doping, and the enhanced interactions between sulfide and carbon atoms bonded to graphitic nitrogen. This study not only provides a better understanding of PCM impact on transformations and fates of organic pollutants in natural environments, but also offer a new regulation strategy for more efficient wastewater treatment processes in PCM-catalyzed engineering systems.

Electrocatalytic biofilm reactor for effective and energyefficient azo dye degradation:the synergistic effect of MnO_(x)/Ti flow-through anode and biofilm on the cathode

Dyeing wastewater treatment remains a challenge.Although effective,the in-series process using electrochemical oxidation as the pre-or post-treatment of biodegradation is long.This study proposes a compact dual-chamber electrocatalytic biofilm reactor(ECBR)to complete azo dye decolorization and mineralization in a single unit via anodic oxidation on a MnO_(x)/Ti flow-through anode followed by cathodic biodegradation on carbon felts.Compared with the electrocatalytic reactor with a stainlesssteel cathode(ECR-SS)and the biofilm reactor(BR),the ECBR increased the chemical oxygen demand(COD)removal efficiency by 24%and 31%(600 mg/L Acid Orange 7 as the feed,current of 6 mA),respectively.The COD removal efficiency of the ECBR was even higher than the sum of those of ECR-SS and BR.The ECBR also reduced the energy consumption(3.07 kWh/kg COD)by approximately half compared with ECR-SS.The advantages of the ECBR in azo dye removal were attributed to the synergistic effect of the MnO_(x)/Ti flow-through anode and cathodic biofilms.Catalyzed by MnIV=O generated on the MnO_(x)/Ti anode under a low applied current,azo dyes were oxidized and decolored.The intermediate products with improved biodegradability were further mineralized by the cathodic aerobic heterotrophic bacteria(non-electrochemically active)under the stimulation of the applied current.Taking advantage of the mutual interactions among the electricity,anode,and bacteria,this study provides a novel and compact process for the effective and energyefficient treatment of azo dye wastewater.

Bacterial Influence on Textile Wastewater Decolorization

The study aims to isolate and optimize bacterial strains having the ability to degrade and decolorize azo dyes produced in the final effluent of textile dying industries. In this regard, ten bacterial strains were isolated from wastewater treatment plants, and most of them were subjected to the colored effluents resulting from dilapidated houses. The ability of these bacterial isolations to use a wide range of azo dyes to determine the sole carbon source was determined. According to these screening testes, two bacterial isolations were selected as the most potent decolorizer for azo dyes, and they were identified as Comamanas acidovorns-TN1 and Burkholdera cepace-TN5. The optimization process started with the addition of 1 g/l yeast extract, where the decolorization ability of the two strains increased sharply and according to this experiment, the two azo dyes, Acid orange 7 and Direct blue 75, were selected to complete the study. The effect of different conditional and chemical factors on the decolorization process of Acid orange 7 and Direct blue 75 by Comamanas acidovorns-TN1 and Burkholdera cepace-TN5 was studied. Factors that contributed to the difference were different pH, temperature, incubation period, inoculum size, carbon source, nitrogen source and the respective concentrations of yeast extract. This study recommends the application of the two most potent bacterial strains in the decolorization of the azo dyes, along with acid orange 7 and direct blue 75, specifically in the industrial effluents under all nutritional and environmental conditions.

Tourmaline activated persulfate for degradation of Sirius Türkis GL 01

The high Fe^(2+)content of tourmaline(TM)has potential of activating a persulfate reaction.However,information pertaining to using TM as an activator in persulfate oxidation process is currently unavailable.In this study,powdered TM was used to activate persulfate(PS)oxidation for decolorization synthetic direct azo dye,Sirius Türkis GL 01(STGL).Findings revealed that decolorization was significantly enhanced by TM/PS combined with ultrasound.A suitable oxidation condition for removal true color was TM 1.5 g/L,PS 5 *10^(-4)M,US 106 W/cm^2(20 min sonication at 20 kHz),and initial pH 6.0,which could completely remove the color and COD of 40 mg/L STGL after 20 min treatment.Oxidation condition under higher TM dosage with higher sonication power is beneficial for generation of sulfate radicals,consequently,promoting the oxidation performance of TM/PS process.Results clearly indicated that Fe-tourmaline,can be potentially used to activate PS oxidation for effective decolorization of wastewater containing direct azo dyes.

Biodegradation of carcinogenic textile azo dyes using bacterial isolates of mangrove sediment

Objective:To evaluate the biodegrading property against carcinogenic azo dyes using bacterial isolates of mangrove sediment.Methods:The bacterial isolates were subjected to submerged fermentation and their growth kinetics were studied.The potential strain was characterized using 16S rDNA sequencing.Results:In the present study,dye degrading bacterial colonies were isolated from the mangrove sediment samples of Parangipettai estuarine area,Tamil Nadu.Of the 30 morphologically different strains isolated,5 showed antagonistic property.The growth kinetics of the two strains,P1 and G1,which showed potent activity were calculated.One particular isolate(P1)showing promising dye degrading potential in the submerged fermentation was further characterized.The strain was identified as Paenibacillus sp.by 16S rDNA sequencing.Conclusions:This study reveals the less explored microflora of mangrove sediments.The novel strain may further be analyzed and used in the treatment of effluent from dye industry so as to reduce the impact of carcinogenic contaminants.

金属氧化物光催化剂降解偶氮染料废水的研究进展

综述了各种金属氧化物,如钛氧化物、锌氧化物、铁氧化物、铜氧化物、铈氧化物及其他金属氧化物复合材料降解偶氮染料的研究进展。它们具有不同的结构、结晶和形态特征,所以具有不同的去除有机物的能力。深入讨论了金属氧化物及其复合材料的光催化机理以及与光催化相关的性能。高效的降解效率、经济可行的光催化材料制备方法以及可控带隙工程是对未来光催化剂的新挑战。

栓菌4281漆酶催化几种不同结构染料脱色

栓菌4281菌株是实验室自主筛选鉴定的新型漆酶高效生产菌株,为探究其漆酶对染料脱色的作用效果,利用栓菌4281漆酶粗酶液对偶氮、蒽醌和苯甲烷类3种类型的染料进行脱色反应,分别考察不同介体类型、温度、pH值、介体浓度、给酶量、反应时间以及金属离子对染料脱色的影响。结果表明:添加介体对染料脱色效率有显著的促进作用,6种染料在8 h内基本反应完全,在各染料最适反应条件下活性蓝、茜素红、甲基橙和结晶紫的最大脱色率分别达到93.9%、92.3%、90%和90%,刚果红和碱性品红脱色率达到76.6%和75%;Mn^(2+)和高浓度的Fe^(2+)对栓菌4281漆酶催化染料脱色作用有一定的抑制,而在Na+、Mg^(2+)、Cu^(2+)、Ni^(2+)和Zn^(2+)金属离子存在下该漆酶仍能对染料保持较高的脱色率。研究表明:栓菌4281漆酶在染料脱色中具有较大的应用潜力;在环境废水的治理中具有良好的应用前景。

降解偶氮染料嗜盐菌的分离、降解特性及机制

高盐限制了普通微生物处理印染废水的效果,分离嗜盐微生物对于提高高盐印染废水的处理效率,具有重要的应用价值。本研究从印染废水的活性污泥中,分离了一株降解酸性金黄G的菌株,通过16S rDNA对该菌进行鉴定,并研究了其降解机理。结果表明,该菌与Exiguobaterium strain ACCC11618同源性最高,属于微小杆菌属。该菌在5%盐度下,8h内对100mg/L的酸性金黄G脱色95%以上。最佳脱色条件是30℃下,pH=7,5%盐度,以酵母粉作为碳源。偶氮还原酶、NADH-DCIP酶是主要的降解酶,盐度抑制了这两种酶的活性。酸性金黄G的偶氮键对称断裂成4-氨基苯磺酸和对氨基二苯胺,进一步降解为二苯胺、苯胺、2-庚酮肟等,降解后产物毒性降低。菌株对不同浓度的酸性金黄G具有耐受性,具有良好的应用潜力。该研究以期为嗜盐菌处理高盐印染废水提供菌种资源和理论依据。

生物沥滤法制备Fe3O4@BC协同PMS对活性红3BS染料的降解

磁性生物炭的制备方法包括物理法和化学法,制备要求较高.本文通过生物沥滤将离子态铁负载到生物炭上,对铁负载生物炭二次热解改性,运用SEM、XRD、XPS、FTIR等手段对材料进行表征,制备出具有磁性的铁基生物炭(Fe_(3)O_(4)@BC).研究材料改性前后及协同PMS对活性红3BS染料的降解过程及机理,探讨了环境因素对染料降解效果的影响,在最佳反应条件下,协同作用对200mg·L^(-1)的活性红3BS染料废水脱色效果达到93.8%.自由基猝灭实验证实反应机理是Fe_(3)O_(4)@BC/PMS体系中自由基和非自由基途径生成的SO_(4)·^(-)和^(1)O_(2)参与了对染料的协同降解.五次循环利用后催化体系对染料的降解效率仍能达到31.2%.本研究为磁性生物炭在高浓度染料废水处理方向提供了新的方法和路径.

固定化脱色菌群对不同偶氮染料脱色效果研究

利用海藻酸钠-聚乙烯醇-沸石作为复合载体对脱色菌群进行固定化,研究固定化脱色菌群对两种偶氮染料脱色效果差异性。结果表明,在不同染料浓度下,固定化脱色菌群对甲基橙的脱色效果均优于活性黑5,当染料浓度为100 mg/L时,对甲基橙和活性黑5的脱色率分别为76.82%和61.37%;不同温度、NaCl浓度下,固定化脱色菌群对两种偶氮染料的脱色效果呈现较大差异性,且兼氧条件更有利于脱色。本研究为利用固定化脱色菌群处理实际染料废水奠定理论基础。