Decolorization and detoxification of two textile industry effluents by the laccase/1-hydroxybenzotriazole system

The aim of this work was to determine the optimal conditions for the decolorization and the detoxification of two effluents from a textile industry—effluent A (the reactive dye bath Bezactive) and effluent B (the direct dye bath Tubantin)—using a laccase mediator system. Response surface methodology (RSM) was applied to optimize textile effluents decolorization. A Box–Behnken design using RSM with the four variables pH, effluent concentration, 1-hydroxybenzotriazole (HBT) concentration, and enzyme (laccase) concentration was used to determine correlations between the effects of these variables on the decolorization of the two effluents. The optimum conditions for pH and concentrations of HBT, effluent and laccase were 5, 1 mM, 50 % and 0.6 U/ml, respectively, for maximum decolorization of effluent A (68 %). For effluent B, optima were 4, 1 mM, 75 %, and 0.6 U/ml, respectively, for maximum decolorization of approximately 88 %. Both effluents were treated at 30 °C for 20 h. A quadratic model was obtained for each decolorization through this design. The experimental and predicted values were in good agreement and both models were highly significant. In addition, the toxicity of the two effluents was determined before and after laccase treatment using Saccharomyces cerevisiae, Bacillus cereus, and germination of tomato seeds.     

Influence of redox mediators and metal ions on synthetic acid dye decolourization by crude laccase from Trametes hirsuta

In this paper, the effect of redox mediators on synthetic acid dye decolourization (Sella Solid Red and Luganil Green) by laccase from Trametes hirsuta cultures has been investigated. All the redox mediators tested, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), 1-hydroxybenzotriazole (HBT) and Remazol Brilliant Blue R (RBBR), led to higher activities than those obtained without mediators addition showing the suitability of the laccase/mediator system (LMS) in the decolourization of acid dyes. HBT was by far the most effective mediator, showing a decolourization percentage of 88% in 10 min for Sella Solid Red and of 49% in 20 min for Luganil Green. On the other hand, the stability of laccase against several metal ions, normally found in textile wastewater, was assessed. Laccase was stable at a concentration of 1mM for 7d against all the metal ions tested except for Zn+2, CrO4(-2), Cd+2, Cr2O7(-2), Fe+2, Cu+2 and especially Hg+2. When the concentration was increased to 10mM laccase stability decreased against all the metals assayed, in particular against Fe+2. In addition, the effect of metal ions on the decolourization process was also studied. It was found that Hg+2 inhibited the dye decolourization process, being the presence of HBT absolutely required for dye decolourization.     

硫酸盐在偶氮染料厌氧生物脱色中的作用

以沼泽红假单胞菌W1为研究对象,考察了厌氧条件下硫酸盐还原对活性黑5(Reactive Black 5,RB5)和直接黄11(Direct Yellow 11,DY11)生物脱色的影响。结果表明,硫酸盐本身对2种染料脱色无明显影响,而硫酸盐的还原产物———硫化物能通过氧化还原介体使2种染料化学脱色,其脱色过程能在3 min内迅速完成。在无介体加入的情况下,硫化物能够通过RB5自身产生的介体加速RB5的脱色;而对于不能产生氧化还原介体的DY11,硫化物对其脱色无明显影响。硫化物经染料氧化后形成的硫单质能够被菌株W1重新转化为硫化物,继续还原染料。     

Decolorization of mixtures of different reactive textile dyes by the white-rot basidiomycete Phanerochaete sordida and inhibitory effect of polyvinyl alcohol

We tried to decolorize mixtures of four reactive textile dyes, including azo and anthraquinone dyes, by a white-rot basidiomycete Phanerochaete sordida. P. sordida decolorized dye mixtures (200 mg l-1 each) by 90% within 48 h in nitrogen-limited glucose-ammonium media. Decolorization of dye mixtures needed Mn2+ and Tween 80 in the media. Manganese peroxidase (MnP) played a major role in dye decolorization by P. sordida. Decolorization of dye mixtures by P. sordida was partially inhibited by polyvinyl alcohol (PVA) that wastewaters from textile industries often contain. This was caused by an inhibitory effect of PVA on the decolorization of Reactive Red 120 (RR120) with MnP reaction system. Second addition of Tween 80 to the reaction mixtures in the presence of PVA improved the decolorization of RR120. These results suggest that PVA could interfere with lipid peroxidation or subsequent attack to the dye.     

Potential of immobilized bitter gourd (Momordica charantia) peroxidases in the decolorization and removal of textile dyes from polluted wastewater and dyeing effluent

Immobilized peroxidases from Momordica charantia were highly effective in decolorizing reactive textile dyes compared to its soluble counterpart. Dye solutions, 50-200 mg/l, were treated with soluble and immobilized bitter gourd peroxidases (specific activity of 99.0 EU per mg protein). The decolorization of dyes with soluble and immobilized enzyme was maximum in the range of pH 3.0-4.0. The effect of different temperatures on the dye decolorization was monitored and it was observed that all the dyes were maximally decolorized at 40 degrees C. In order to examine the operational stability of the immobilized preparation, the enzyme was repeatedly exploited for the decolorization of the dyes from fresh batch of dye solutions. Even after 10 cycles in each case the immobilized preparation retained nearly 50% of the initial enzyme activity. The immobilized enzyme exhibited more than 90% of the original activity while the soluble enzyme lost 33% of the initial activity when stored for 40 d at room temperature. Mixtures of three, four and eight dyes were prepared and treated with soluble and immobilized bitter gourd peroxidase. Each mixture was decolorized by more than 80% when treated with immobilized enzyme. Dyeing effluent collected from local dyers was treated with both types of enzyme preparations. Immobilized enzyme was capable of removing remarkably high concentration of color from the effluent. TOC content of soluble and immobilized enzyme treated individual dyes, mixture of dyes and dyeing effluent was determined and it was observed that higher TOC was removed after treatment with immobilized enzyme.     

Phytoremediation of textile effluent and mixture of structurally different dyes by Glandularia pulchella (Sweet) Tronc

Plants of Glandularia pulchella (Sweet) Tronc. performed decolorization of structurally different dyes to varying extent because of induction of different set of enzymes in response to specific dyes. Differential pattern of enzyme induction with respect to time was obtained for lignin peroxidase, veratryl alcohol oxidase, tyrosinase and dichlorophenolindophenol reductase during the decolorization of dye mixture, whose combined action resulted in greater and faster decolorization of dyes. HPLC, FTIR and High Performance Thin Layer Chromatography (HPTLC) analysis confirmed degradation of dyes from textile effluent and mixture. HPTLC demonstrated progressive decolorization of dye mixture along with preferential degradation of the dyes. G. pulchella showed reduction in American Dye Manufacturer's Institute from 405 to 21 and 418 to 22, in case of textile effluent and mixture of dyes respectively. The non-toxic nature of the metabolites of degraded textile dye effluent and mixture of dyes was revealed by phytotoxicity studies.     

Electrochemical decolourisation of structurally different dyes

The electrochemical decolourisation of structurally different dyes (bromophenol blue, indigo, poly R-478, phenol red, methyl orange, fuchsin, methyl green and crystal violet) by means of the application of DC electric current was assessed. It was found that the electrochemical process allowed a colour removal of all dyes studied, although the decolourisation rate largely depended on the chemical structure of the different dyes. Nearly complete decolourisation was achieved for bromophenol blue followed by methyl orange and methyl green, whereas phenol red was hardly decolourised (30% in 60 min). In mixtures of two dyes, the decolourisation rate became similar for both dyes. However, the addition of a redox mediator, (Co(2+/3+)) clearly enhanced the degradation rate of all tested dyes, but the simplest dye molecules were attacked firstly, followed by dyes with more complex chemical structures. The results revealed the suitability of the process to effectively decolourise wastewaters from dyeing process.     

Effect of different redox mediators during thermophilic azo dye reduction by anaerobic granular sludge and comparative study between mesophilic (30 degrees C) and thermophilic (55 degrees C) treatments for decolourisation of textile wastewaters

The impact of different redox mediators on colour removal of azo dye model compounds and textile wastewater by thermophilic anaerobic granular sludge (55 degrees C) was investigated in batch assays. Additionally, a comparative study between mesophilic (30 degrees C) and thermophilic (55 degrees C) colour removal was performed with textile wastewater, either in the presence or absence of a redox mediator. The present work clearly evidences the advantage of colour removal at 55 degrees C compared with 30 degrees C when dealing with azo coloured wastewaters. The impact of the redox mediators anthraquinone-2,6-disulfonate (AQDS), anthraquinone-2-sulfonate (AQS) and riboflavin was evident with all dyes, increasing decolourisation rates up to 8-fold compared with the mediator-free incubations. The generation of the hydroquinone form AH2QDS, i.e. the reduced form of AQDS, was extremely accelerated at 55 degrees C compared with 30 degrees C. Furthermore, no lag-phase was observed at 55 degrees C. Based on the present results we postulate that the production/transfer of reducing equivalents was the process rate-limiting step, which was accelerated by the temperature increase. It is conclusively stated that 55 degrees C is a more effective temperature for azo dye reduction than 30 degrees C, which on the one hand can be attributed to the faster production/transfer of reducing equivalents, but also to the decrease in activation energy requirements.     

Microbial decolorization of synthetic dyes and reactive dyes of industrial effluents by using a novel fungus Aspergillus proliferans

A decolorizing fungal strain was isolated and identified by the morphology and genotypic characterization as Aspergillus proliferans. The effect of A. proliferans on decolorization of synthetic dyes (70 mg ml(-1)) and colored effluent was evaluated in liquid culture medium. A. proliferans expressed their effective decolorization activity in effectual decolorization of synthetic dyes and industrial effluent. Synthetic dyes were decolorized by 76 to 89% within 6 days of treatment and 73.5% of color was removed in industrial effluent within 8 days. The addition of optimum carbon and nitrogen sources were effectively stimulated the decolorization activity. The high concentration of glucose repressed the decolorization activity and supplementation of yeast extract has significantly enhanced the effluent decolorization at p < 0.05. Laccase enzyme was isolated from liquid state fermentation, which showed significant enzyme activity (10,200 Uml(-1)) at p < 0.005. The crude enzyme decolorizes the dyes aniline blue and congo red in 14 hours (40.9 to 70%) and the effluent in 14 hours (88.6%). Moreover, the culture free supernatant without the fungal biomass has also effectively decolorized the effluent and synthetic dyes. The fungi Aspergillus proliferans was used not only for decolorization but also for better bioremediation of industrial effluent.     

Color removal from dye containing effluents by treatment with manganese solid waste

A solid waste from manganese dioxide industry was studied for possible use to remove color from dye containing effluents. Artificial mixtures with direct, basic and acid dyes were studied. This material was found to be an effective adsorbent for the class of direct dyes.     

Degradation of azo dyes using low iron concentration of Fenton and Fenton-like system

This study investigated Fenton and Fenton-like reactions at low iron concentration (相似文献   

Phanerochaete chrysosporium吸附载体的选择及染料降解研究

研究了游离细胞与载体吸附培养、不同载体材料对Phanerochaete chrysosporium进行连续染料脱色及产酶能力的影响。结果表明,P.chrysosporium可在载体上良好生长,甚至生长到载体内部。木屑、玉米芯、花生壳3种载体材料中,以木屑载体吸附培养物的持续脱色和产酶效果最佳,该培养物经三轮连续脱色后对染料RB5仍能达到最高95%的脱色率,并产生596 U/L锰依赖过氧化物酶（MnP）和1 326 U/L木质素过氧化物酶（LiP）,对染料的持续脱色和产酶能力明显优于游离细胞培养物。     

Decolorization and degradation of H-acid and other dyes using ferrous-hydrogen peroxide system

In this study, advanced oxidation process utilizing Fenton's reaction was investigated for the decolorization and degradation of two commercial dyes viz., Red M5B, Blue MR and H-acid, a dye intermediate used in chemical industries for the synthesis of direct, reactive and azo dyes. Effect of Fe2 +, H2O2, pH, and contact time on the degradation of the dyes was studied. Maximum color and COD removal was obtained for Red MSB, H-acid and Blue MR at 10-25 mg/l of Fe2+ dose and 400-500 mg/l of H2O2 dose at pH 3.0. The initial oxidation reaction was found to fit into first order rate kinetics and the rate of oxidation of H-acid was higher than the other dyes. Release of chloride and sulfate from the Fenton's treated Red M5B dye and sulfate from H-acid and Blue MR indicates that the dye degradation proceeds through cleavage of the substituent group.     

Phanerochaete chrysosporium吸附载体的选择及染料降解研究

研究了游离细胞与载体吸附培养、不同载体材料对Phanerochaete chrysosporium进行连续染料脱色及产酶能力的影响。结果表明,P. chrysosporium可在载体上良好生长,甚至生长到载体内部。木屑、玉米芯、花生壳3种载体材料中,以木屑载体吸附培养物的持续脱色和产酶效果最佳,该培养物经三轮连续脱色后对染料RB5仍能达到最高95%的脱色率,并产生596 U/L锰依赖过氧化物酶（MnP）和1 326 U/L木质素过氧化物酶（LiP）,对染料的持续脱色和产酶能力明显优于游离细胞培养物。     

亚铁羟基络合物还原转化水溶性偶氮染料

偶氮染料是印染工艺中应用最广泛的一类染料,目前染料废水脱色是污水处理难题。亚铁混凝处理染料废水过程中可能存在亚铁的还原作用,本实验制备了比溶解态亚铁更具还原反应活性的亚铁羟基络合物(ferrous hydroxycomplex,FHC),以5种不同类型的水溶性偶氮染料为目标污染物,研究FHC还原水溶性偶氮染料的脱色性能。实验结果表明,FHC对活性艳红X-3B、酸性大红GR和阳离子红X-GRL有较好的还原脱色效果,仅投加含铁89.6 mg/L的FHC,染料脱色率达到90%以上,继续增大FHC投加量可以完全脱色;中性枣红GRL的FHC还原脱色效果较差,需加入313.6 mg/L的FHC才能达到90%以上脱色率;134.4 mg/L的FHC能够将直接耐酸大红4BS完全脱色,但其脱色主要以混凝沉淀为主;溶液pH对FHC的还原性能产生重要影响,FHC还原染料脱色的适宜的pH值范围为4～10。该研究为亲水性染料脱色提供了一种新的技术,也为FHC运用于印染废水脱色提供了理论基础。     

Biogenic sulphide plays a major role on the riboflavin-mediated decolourisation of azo dyes under sulphate-reducing conditions

The effect of high concentrations of sulphate on the reductive decolourisation of different azo dyes by anaerobic sludge was studied in batch cultures. Sludge cultures were pre-incubated under sulphate-reducing conditions prior addition of dyes. Little or no effects of sulphate (5-10 g sulphate l(-1)) on the rate of decolourisation of Reactive Orange 14 (RO14), Direct Blue 53 (DB53) and Direct Blue 71 (DB71) were observed when no external redox mediator was provided. However, an increase in sulphate concentration, in the presence of riboflavin (20 microM), enhanced the decolourisation of all dyes. The first-rate constant of decolourisation (k) was increased up to 2-, 3.6- and 2-fold for RO14, DB53 and DB71, respectively, by supplying high sulphate concentrations, compared to the controls lacking sulphate, in the presence of the redox mediator. Sulphate reduction did not take place during the course of azo reductions, but was only evident before dye addition and after complete decolourisation, suggesting azo dyes reduction out-competed sulphate reduction for the available reducing equivalents. The experimental data suggest that reduction of azo dyes by riboflavin, which had been reduced by biogenic sulphide, was the major mechanism implicated during decolourisations, which was corroborated by abiotic incubations. Riboflavin greatly accelerated the abiotic reduction of RO14, so that the k value was increased up to 44-fold compared to the control lacking riboflavin.     

Biological decolorization of reactive anthraquinone and phthalocyanine dyes under various oxidation-reduction conditions.

The decolorization of two anthraquinone dyes (Reactive Blue 4 [RB4] and Reactive Blue 19 [RB19]) and two phthalocyanine dyes (Reactive Blue 7 [RB7] and Reactive Blue 21 [RB21]) was investigated at an initial dye concentration of 300 mg/L using an unacclimated, enrichment culture. The culture was fed a mixture of organic compounds and maintained initially under aerobic conditions, and then progressively developed anoxic/ anaerobic conditions. Biotransformation-related decolorization of the dyes did not take place under aerobic conditions, but use of the feed organic mixture and biomass production by the enrichment culture were not affected. Complete ammonia removal occurred in the control and all dye-amended cultures. The development and extent of nitrification were much lower in the latter cultures, in which ammonia removal via air stripping was the dominant mechanism. Prolonged incubation of the culture under anoxic/anaerobic conditions with multiple carbon source additions resulted in a high decolorization extent of anthraquinone dyes (over 84%) and only partial decolorization of phthalocyanine dyes (49 to 66%). Development of significant methanogenic activity took place in the control and, to a lesser extent, in the two phthalocyanine dye-amended cultures, but the anthraquinone dyes severely inhibited the development of methanogenic activity. The RB4 and RB19 decolorization was attributed to nonreversible, microbially mediated dye transformation(s), demonstrated by the accumulation of decolorization products with absorbance maxima in the 420- to 460-nm region. The decolorization of RB4 and RB19 followed Michaelis-Menten kinetics. At an initial dye concentration of 300 mg/L, the observed maximum decolorization rate per unit biomass was 9.1 and 37.5 mg dye/mg volatile suspended solids x day for the RB4 and RB19, respectively. Thus, partial decolorization of reactive phthalocyanine dyes and extensive biological decolorization of reactive anthraquinone dyes is feasible only under anoxic/anaerobic conditions.     

Decolorization and degradation of dyes with mediated fenton reaction.

A mediated Fenton system has been evaluated for decolorization of several types of dyes. The result shows that the Fenton system with a dihydroxybenzoic acid (DHBA) chelator-mediator effectively reduced the color of a diluted solution of Carta Yellow RW liquid, Carta Yellow G liquid, and Cartasol Red 2GF liquid dye to a colorless level after 90 minutes of treatment with 100 microM iron II (Fe[II]), 100 microM DHBA, and 10 mM hydrogen peroxide (H2O2) at room temperature. Our results show that compared to a neat Fenton process, the mediated Fenton decolorization process increased the production, and therefore the effective longevity, of hydroxyl radical (OH) species to increase the decolorization efficiency. Our results suggest that application of this system would also result in an increase in dissolved oxygen (DO) in solution, which in turn would result in reduction of chemical oxygen demand (COD), biochemical oxygen demand (BOD), and total organic carbon (TOC).     

白腐真菌F1对染料脱色特性的研究

本研究从我国生物资源中筛选出一株白腐真菌F1,确定了其生长条件 ,实现了扩大培养 ,并研究了F1与黄孢原毛平革菌对 4种难降解染料的脱色效果。试验结果表明 ,F1对中性深黄GRL、酸性媒介漂蓝B和刚果红的脱色效率都超过 90 % ;白腐真菌能在短时间内将有毒染料酸性媒介漂蓝B降低到较低浓度 ;白腐真菌对染料脱色的同时 ,自身能够繁殖生长。     

Copper-ligand complex for the decolorization of synthetic dyes

The reaction system containing Cu(II), hydrogen peroxide and D-arabinono-1,4-lactone was found to be effective in the decolorization and reduction of toxicity of azo, thiazine-, triphenylmethane- and anthraquinone-based synthetic dyes. More than 85% decolorization was obtained with 100ppm Acridine Orange, Azure B, Chicago Sky Blue 6B, Crystal Violet, Evans Blue, Poly B-411, Reactive Blue 2, Reactive Blue 5, and Remazol Brilliant Blue R incubated for 24h in the presence of 10mM CuSO(4), 20mM D-arabinono-1,4-lactone and 80 mM H(2)O(2). The rate of decolorization was not affected by pH in the range of 3-9. The rapid decolorization was accompanied by a fast decomposition of H(2)O(2) in the reaction mixture and by a fast production of hydroxyl radicals.