Maximum Decolorization Rate Research Articles

Optimized decolorization of two poly azo dyes Sirius Red and Sirius Blue using laccase-mediator system.

Factors, namely pH, laccase-like activity, dyes concentration as well as 1-Hydroxybenzotriazole (HBT) concentration was examined. The results indicated that the maximum decolorization yield and rate reached 98.30 ± 0.10% and 5.84 ± 0.01%/min, respectively for Sirius Blue, and 99.34 ± 0.47% and 5.85 ± 0.12%/min, respectively for Sirius Red after 4h. The presence of the redox mediator 1-hydroxybenzotriazole (HBT) greatly improved the decolorization levels. The optimum concentrations of HBT, dyes, and laccase were 0.62mM, 50mg/L, and 0.89 U/mL respectively at pH 4.58 for both dyes. Phytotoxicity tests using treated and untreated dyes proved that the applied treatment slightly decreased the toxicity of the by-products. However, the germination index (GI) increased from 14.6 to 36.08% and from 31.6 to 36.96% for Sirius Red and Sirius Blue, respectively. The present study focused on the treatment of two recalcitrant azo dyes, namely: Sirius Blue (Direct Blue 71) and Sirius Red (Direct Red 80). The decolorization was performed using cell-free supernatant from Coriolopsis gallica culture with high laccase activity. Response surface methodology (RSM) and Box-Behnken design were applied to optimize the decolorization of the two tested dyes. The effect of four.

Response surface methodology for low-energy consumption electro-Fenton process for xanthene dye electrochemical degradation

Erythrosine B (EB) is a dye widely used in the food and textile industries. Despite many studies that have been proposed in the literature about the electrochemical oxidation of dyes, few studies considered such recalcitrant xanthene compound, although it has been recognized as a threat to health and the environment. Then, this study investigates the oxidation of EB by a homogeneous electro-Fenton process using iron (II) sulfate heptahydrate as a catalyst, carbon felt cathode, and Ti/RuO2 anode. The treated synthetic wastewater contains 100 mg L−1 of EB and has a pH = 3. The effects of three independent variables have been considered for process optimization, such as applied current intensity (0.1–0.5 A), iron concentration (1–10 mM), and stirring rate (100–1000 rpm). Their interactions were investigated considering response surface methodology (RSM) based on Doehlert design as optimization method. EB removal efficiency and energy consumption were considered as model responses after 30 min of electrolysis. Analysis of variance (ANOVA) revealed that the quadratic model was adequately fitted to the experimental data with R2 (0.9819), adj-R2 (0.9276), and low Fisher probability (< 0.0181) for the EB removal model, and R2 (0.9968), adj-R2 (0.9872) and low Fisher probability (< 0.0014) relative to the energy consumption model, suggesting a robust statistical significance. The energy consumption model significantly depends on current density, as expected. The foregoing results obtained by RSM led to the following optimal conditions for EB degradation: current intensity of 0.2 A, iron concentration of 9.397 mM, and stirring rate of 500 rpm, which gave a maximum decolorization rate of 98.15% with a minimum energy consumption of 0.74 kWh m−3 after 30 min of electrolysis. The competitiveness of the electro-Fenton process has been confirmed by the literature analysis proposed as well as by the preliminary economic analysis proposed in the second section of the study.Graphical abstract

Effect of Current Density on the Corrosion Resistance and Photocatalytic Properties of Cu-Ni-Zn0.96Ni0.02Cu0.02O Nanocomposite Coatings.

2 at.% Cu + 2 at.% Ni were co-doped in ZnO nanoparticles by a simple hydrothermal method, and then the modified nanoparticles were compounded into Cu-Ni alloy coatings using an electroplating technique. The effects of the current density (15-45 mA/cm2) on the phase structure, surface morphology, thickness, microhardness, corrosion resistance, and photocatalytic properties of the coatings were investigated. The results show that the Cu-Ni-Zn0.96Ni0.02Cu0.02O nanocomposite coatings had the highest compactness and the best overall performance at a current density of 35 mA/cm2. At this point, the co-deposition rate reached its maximum, resulting in the deposition of more Zn0.96Ni0.02Cu0.02O nanoparticles in the coating. More nanoparticles were dispersed in the coating with a better particle strengthening effect, which resulted in a minimum crystallite size of 15.21 nm and a maximum microhardness of 558 HV. Moreover, the surface structure of the coatings became finer and denser. Therefore, the corrosion resistance was significantly improved with a corrosion current density of 2.21 × 10-3 mA/cm2, and the charge transfer resistance was up to 20.98 kΩ·cm2. The maximum decolorization rate of the rhodamine B solution was 24.08% under ultraviolet light irradiation for 5 h. The improvement in the comprehensive performance was mainly attributed to the greater concentration of Zn0.96Ni0.02Cu0.02O nanoparticles in the coating, which played the role of the particle-reinforced phase and reduced the microstructure defects.

Fabrication of modified electrode by reduced graphene oxide (rGO) and polyaniline (PANI) for enhancing azo dye decolorization in bio-electrochemical systems (BESs)

Bio-electrochemical systems (BESs) have attracted wide attention in the field of wastewater treatment owing to their fast electron transfer rate and high performance. Unfortunately, the low electro-chemical activity of carbonaceous materials commonly used in BESs remains a bottleneck for their practical applications. Especially, for refractory pollutants remediation, the efficiency is largely limited by the cathode property in term of (bio)-electrochemical reduction of highly oxidized functional groups. Herein, a reduced graphene oxide (rGO) and polyaniline (PANI) modified electrode was fabricated via two-step electro-deposition using carbon brush as raw material. Benefiting from the modified graphene sheets and PANI nanoparticles, the rGO/PANI electrode shows highly conductive network with the electro-active surface area increased by 12 times (0.013 mF cm−2) and the charge transfer resistance decreased by 92% (0.23Ω) comparing with the unmodified one. Most importantly, the rGO/PANI electrode used as abiotic cathode achieves highly efficient azo dye removal from wastewater. The highest decolorization efficiency reaches 96 ± 0.03% within 24 h and the maximum decolorization rate is as high as 20.9 ± 1.45 g h−1·m−3. The features of improved electro-chemical activity and enhanced pollutant removal efficiency provide a new insight toward development of high performance BESs via electrode modification for practical application.

Decolorization Performance of a Methyl Benzyl Diallyl Quaternary Ammonium Salt Copolymer in a Simulated Reactive Dyeing Wastewater

The source of dyeing wastewater and the composition of pollutants are very complex, direct discharge will bring great harm to living environment, and cause waste of water resources. For the treatment of reactive dyeing wastewater, this work developed and synthesized a novel cationic flocculant called Poly (DMDAAC-co-DAMBAC), which was made by copolymerizing dimethyl-diallyl-ammonium chloride (DMDAAC) and methyl-benzyl-diallyl-ammonium chloride (DAMBAC). To assess its flocculation effects, flocculation decolorization studies with 3RF reactive yellow, KN−R reactive blue, and 3BF reactive red were conducted. The copolymers′ lipophilicity considerably increased once atyl groups were added. The experimental results showed that Poly(DMDAAC-co-DAMBAC) had an optimal decolorization rate of over 94 % for three reactive dyes and a maximum decolorization rate of roughly 80 % for CODMn, both of which were significantly higher than those of PDMDAAC and nearly on par with those of PDAMBAC with a comparable viscosity. Instead, Theoretical calculations of the binding energy of the results demonstrated the accuracy of the findings. The study illustrated the flocculation mechanism and laid the foundation for further application of Poly(DMDAAC-co-DAMBAC).

Decolorization of Dyes in the Bioelectrochemical System Depending on the Immobilization of &lt;i&gt;Shewanella oneidensis&lt;/i&gt; MR-1 Cells on the Anode Surface and Electrical Stimulation of the External Circuit

The effect of the polarity of the electrical stimulation of the external circuit of the bioelectrochemical systems, as well as the immobilization of Shewanella oneidensis MR-1 cells containing the DyP peroxidase gene on the rate of discoloration of dyes of different types was found. For the crystal violet triphenylmethane dye, the maximum decolorization rate by suspended S. oneidensis MR-1 cells 2.05 ± 0.07 μM/h was noted in the case of connecting a 1.2 V direct polarity DC voltage source. One of the minimum rates was observed in the case of reverse polarity of the connection. In the case of cells immobilized on the anode, the rate was higher, reaching 2.91 ± 0.09 μM/h and did not decrease with increasing substrate concentration. The lowest values were also noted for the reverse connection of the voltage source. In case of the azo dye congo red, the maximum rate was found for a source with direct connection and an open circuit (0.26 ± 0.01 and 0.29 ± ± 0.02 μM/h, respectively), the minimum value is 0.11 ± 0.02 μM/h for reverse connection. For the crystal violet decolorization products, a significant decrease in the intensity of the main absorption peak at 590 nm band was found, with no notable hypsochromic shift. The qualitative changes in the decolorization products composition are indicated by the appearance, in case of a direct polarity of the ionistor connection, of a new absorption maximum in the region of 360 nm. The results may be of interest for the development of new methods of bioelectrochemical cleaning.

Enhancing biomass yield, nutrient removal, and decolorization from soy sauce wastewater using an algae-fungus consortium

Soy sauce wastewater (SW), owing to its high levels of nutrients and chromaticity, may cause serious eutrophication if discharged directly into natural water bodies. Microalgae and fungi have great potential for removing nutrients and chromaticity from wastewater and producing value-added biomass. We determined the most robust algal strain, which was isolated from local water bodies, screened in SW, and identified using 18S rRNA gene sequencing analysis. Subsequently, the algal strain and fungal strain, Penicillium sp. were mono- or co-cultured in SW at different inoculum amounts or ratios for achieving maximum biomass yield, nutrient removal, and decolorization from SW. The results suggested that locally isolated NCU-183 (Nanchang University-183) was the most robust algal strain of the four candidates and was identified as Chlorella pyrenoidosa. In monoculture, the maximum biomass yield (2.2 g L−1) and nutrient removal rates (564.7, 20.2, 22.3, and 3.3 mg L−1 d−1 for chemical oxygen demand (COD), ammonium nitrogen (NH4+-N), total nitrogen (TN), and total phosphorus (TP), respectively) were obtained from algal cultivation with an initial dry weight of 0.25 g L−1 (i.e., 5 × 106 cells mL−1) in 100 % SW; the maximum decolorization rate (55.0 PCU d−1) was attained from fungal cultivation at an inoculum density of 103 spores mL−1. Compared to monoculture, the constructed algae-fungus consortium showed higher biomass yield (2.8 g L−1), nutrient removal rates (616.7, 22.8, 25.0, and 4.1 mg L−1 d−1 for COD, NH4+-N, TN, and TP, respectively), and decolorization rate (61.0 PCU d−1) in 100 % SW at an inoculum ratio of algal cells to fungal spores of 5000:1. The consortium biomass with higher protein content (65.3 %) had great potential as a value-added feedstock for animal/fish feed production as compared to the protein-rich C. pyrenoidosa biomass (62.6 %). In conclusion, the algae-fungus consortium showed practical utility for SW remediation and value-added biomass production.

Optimization of the decolorization conditions of Rose Bengal by using Aspergillus niger TF05 and a decolorization mechanism.

Aspergillus niger TF05 was applied to decolorize Rose Bengal dye. The effects of carbon source, nitrogen source, metal ion and spore concentration on Rose Bengal treatment with A. niger TF05 were studied. A Plackett–Burman design (PBD) and a uniform design (UD) were used to optimize the decolorization conditions of A. niger TF05 and enhance its decolorization effect. The mechanism of Rose Bengal decolorization by A. niger TF05 was examined by analysing degradation products via UV–visible light spectroscopy, IR spectroscopy and GC-MS. The best decolorization effect was achieved in the single factor test with glucose and ammonium chloride as carbon and nitrogen sources, respectively. Mg2+ was an essential ion that could improve the mould ball state and adsorption efficiency if the spore concentration was maintained at 106 spores ml–1. The optimal decolorization conditions obtained using the PBD and UD methods were 11.5 g l−1 glucose, 6.5 g l−1 ammonium chloride, 0.4 g l−1 magnesium sulphate, pH 5.8, 28 °C, 140 r.p.m. rotational speed, 0.18 g l−1 dye concentration, 0.5 ml of inocula and 120 h decolorization time. Under these conditions, the maximum decolorization rate was 106%. Spectral analysis suggested that the absorption peak of the product changed clearly after decolorization; GC-MS analysis revealed that the intermediate product tetrachlorophthalic anhydride formed after decolorization. The combined use of the PBD and UD methods can optimize multi-factor experiments. A. niger TF05 decolorized Rose Bengal during intracellular enzymatic degradation after adsorption.

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.

High-rate anaerobic decolorization of methyl orange from synthetic azo dye wastewater in a methane-based hollow fiber membrane bioreactor

Anaerobic biological techniques are widely used in the reductive decolorization of textile wastewater. However, the decolorization efficiency of textile wastewater by conventional anaerobic biological techniques is generally limited due to the low biomass retention capacity and short hydraulic retention time (HRT). In this study, a methane-based hollow fiber membrane bioreactor (HfMBR) was initially inoculated with an enriched anaerobic methane oxidation (AOM) culture to rapidly form an anaerobic biofilm. Then, synthetic azo dye wastewater containing methyl orange (MO) was fed into the HfMBR. MO decolorization efficiency of ∼ 100 % (HRT = 2 to 1.5 days) and maximum decolorization rate of 883 mg/L/day (HRT = 0.5 day) were obtained by the stepwise increase of the MO loading rate into the methane-based HfMBR. Scanning electron microscopy (SEM) and fluorescence in situ hybridization (FISH) analysis visually revealed that archaea clusters formed synergistic consortia with adjacent bacteria. Quantitative PCR (qPCR), phylogenetic and high-throughput sequencing analysis results further confirmed the biological consortia formation of methane-related archaea and partner bacteria, which played a synergistic role in MO decolorization. The high removal efficiency and stable microbial structure in HfMBR suggest it is a potentially effective technique for high-toxic azo dyes removal from textile wastewater.

Effective removal of methylene blue and orange II by subsequent immobilized laccase decolorization on crosslinked polymethacrylate/carbon nanotubes

In this research, methylene blue (MB) and orange II (OII) were effectively removed through subsequent immobilized laccase degradation on crosslinked polymethacrylate (PMMA)/carbon nanotubes (CNTs). PMMA was coated on CNTs by microemulsion polymerization, and then laccase was immobilized on the PMMA-CNTs. Laccase immobilized on PMMA-CNTs shows a high catalytic ability and stable reusability. The immobilized laccase exhibits a high specific laccase activity and a high decolorization rate on the azo dyes, which the maximum decolorization rate for MB can reach 96% and maximum decolorization rate for OII is 74%. Additionally, the decolorization rate was decreased only about 10% after 10 successive cycles. The immobilized laccase can be a promising multifunction material in wastewater treatment, which would be applied in the decolorization of azo dyes.

CS@MnO2 core-shell nanospheres with enhanced visible light photocatalytic degradation

Flower-like core-shell MnO2-coated carbon aerogels (CS@MnO2) were prepared via a facile hydrothermal process. CS@MnO2 composites can remove dyes from aqueous solution, such as Methylene blue (MB), Congo red (CR), and Rhodamine B (RhB). CS@MnO2 presents an excellent decolorization effect of anionic and cationic dyes. Notably, the maximum decolorization rate for cationic dyes reached 99.5% (wt%), together with a decolorization rate of 90% for the anionic dye. Our work not only developed CS@MnO2 core-shell nanospheres as a superior photocatalyst, but also provided a new strategy for many other related applications.

Co-immobilization of laccase and TEMPO onto amino-functionalized magnetic Fe3O4 nanoparticles and its application in acid fuchsin decolorization

BackgroundLaccase, a multicopper oxidase that catalyzes the oxidation of phenols, aromatic amines, and benzenethiols, has attracted much attention in applications of organic synthesis, bioremediation, and pulp/textile bleaching. However, free laccases cannot be recycled and are easily inactivated in diverse environmental conditions. Enzyme immobilization is a promising strategy to improve stability, resistance to extreme conditions, and reusability of laccase.ResultsIn this study, amino-functionalized magnetic Fe3O4 nanoparticles were synthesized for co-immobilization of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) and laccase by glutaraldehyde cross-linking method. The magnetic nanoparticles were characterized with FTIR, XRD and VSM. Cyclic voltammetry was carried out to verify electrochemical behaviors of the co-immobilized laccase and TEMPO nanoparticles. When the co-immobilized laccase and TEMPO nanoparticles were used to decolorize acid fuchsin, the maximum decolorization rate of 77.41% was obtained with the ratio of TEMPO to laccase being 0.3 mM/g:120 U/g.ConclusionThe co-immobilized nanoparticles retained above 50% residual activity after eight cycles of operation, which presented an approach to develop a co-immobilized laccase and mediator system for potential industrial application.

Decolorization of acid, disperse and reactive dyes by Trametes versicolor CBR43

ABSTRACTThe mycoremediation has been considered as a promising method for decolorizing dye wastewater. To explore new bioresource for mycoremediation, a new white-rot fungus that could decolorize various dyes commonly used in textile industries was isolated, and its ligninolytic enzyme activity and decolorization capacity were characterized. The isolated CBR43 was identified as Trametes versicolor based on the morphological properties of its fruit body and spores, as well as through partial 18S rDNA gene sequences. Isolated CBR43 displayed high activities of laccase and Mn-dependent peroxidase, whereas its lignin peroxidase activity was relatively low. These ligninolytic enzyme activities in potato dextrose broth (PDB) medium were enhanced by the addition of yeast extract (1–10 g L−1). In particular, lignin peroxidase activity was increased more than 5 times in the PDB medium amended with 10 g L−1 of yeast extract. The CBR43 decolorized more than 90% of 200 mg L−1 acid dyes (red 114, blue 62 and black 172) and reactive dyes (red 120, blue 4, orange 16 and black 5) within 6 days in the PDB medium. CBR43 decolorized 67% of 200 mg L−1 acid orange 7 within 9 days. The decolorization efficiencies for disperse dyes (red 1, orange 3 and black 1) were 51–80% within 9 days. The CBR43 could effectively decolorize high concentrations of acid blue 62 and acid black 172 (500–700 mg L−1). The maximum dye decolorization rate was obtained at 28°C, pH 5, and 150 rpm in the PDB medium. T. versicolor CBR43 had high laccase and Mn-dependent peroxidase activities, and could decolorize a wide variety of dyes such as acid, disperse and reactive textile dyes. This fungus had decolorizing activities of azo-type dyes as well as anthraquinone-type dyes. T. versicolor CBR43 is one of promising bioresources for the decolorization of textile wastewater including various dyes.

Decolorization of complex dyes and textile effluent by extracellular enzymes of Cyathus bulleri cultivated on agro-residues/domestic wastes and proposed pathway of degradation of Kiton blue A and reactive orange 16.

In this study, the white-rot fungus Cyathus bulleri was cultivated on low-cost agro-residues, namely wheat bran (WB), wheat straw (WS), and domestic waste orange peel (OP) for production of ligninolytic enzymes. Of the three substrates, WB and OP served as good materials for the production of laccase with no requirement of additional carbon or nitrogen source. Specific laccase activity of 94.4Umg-1 extracellular protein and 21.01Umg-1 protein was obtained on WB and OP, respectively. Maximum decolorization rate of 13.6μmolh-1U-1 laccase for reactive black 5 and 22.68μmolh-1U-1 laccase for reactive orange 16 (RO) was obtained with the WB culture filtrate, and 11.7μmolh-1U-1 laccase for reactive violet 5 was observed with OP culture filtrate. Importantly, Kiton blue A (KB), reported not to be amenable to enzymatic degradation, was degraded by culture filtrate borne activities. Products of degradation of KB and RO were identified by mass spectrometry, and a pathway of degradation proposed. WB-grown culture filtrate decolorized and detoxified real and simulated textile effluents by about 40%. The study highlights the use of inexpensive materials for the production of enzymes effective on dyes and effluents.

Removal of textile dye reactive green-19 using bacterial consortium: Process optimization using response surface methodology and kinetics study

In the present work, removal of a textile dye Reactive Green-19 from the aqueous medium was investigated using a developed bacterial consortium. Optimal combinations of three significant process parameters pH (5–10); incubation temperature (25–45°C); and Yeast extract concentration (0–1.5g/100mL) were determined using response surface methodology. Experiments were based on Box–Behnken surface statistical design, performed at initial dye concentration of 100mg/L as a fixed input parameter. Regression analysis displayed good fit of the experimental data to the second-order polynomial model with the coefficient of determination (R2)=0.9974 and Predicted (R2)=0.9677. The adequacy of the model was established with various descriptive statistics like lack of fit, coefficient of variation, predicted residual sum of squares, and adequate precision. The optimal decolorization conditions were as follows: temperature, 32.04°C; pH, 8.3 and Yeast Extract concentration, 1.16g/100mL. Under optimized conditions, more than 97% removal efficiency was achieved within 24h. First order kinetic fitted well with experimental data for different concentrations of dye Reactive green-19. Michaelis-Menten kinetics was used to define the apparent relationship between the decolorization rate and the dye concentration at optimized condition. The double reciprocal plot for kinetics yield maximum decolorization rate, Vm=120.48h−1 and half saturation constant, Km=1674mg/L. Biodegradation of dye was confirmed through UV–vis spectroscopy, Fourier transform infra-red spectroscopy, and High-performance liquid chromatography analysis. Reactive green-19 degradation products were identified through GC–MS analysis.

Decolorization of Remazol Brilliant Blue R using a novel acyltransferase-ISCO (in situ chemical oxidation) coupled system

The feasibility of a novel perhydrolase-ISCO (in situ chemical oxidation) coupled technology for decolorization process of dye effluent was investigated. All the tested synthetic dyes, Malachite green chloride, Indigo Carmine, Rhodamine B, Remazol Brilliant Blue R (RBBR) and Orange I, could be decolorized using the novel process technology. In the RBBR effluent model, the optimized parameters for decolorization process using free acyltransferase as biocatalyst were as follows: 4U/mL acyltransferase dosage, 40:1 molar ratio of ethyl acetate to hydrogen peroxide, and 80mg/L RBBR original concentration in 20mmol/L disodium hydrogen phosphate-citrate buffer, pH5.0. Under the optimal parameters for RBBR decolorization process, the maximum decolorization rate reached 81.11% at 30°C for 6h. The decolorization rate could be further increased to 95.08% in 10min when acyltransferase CLEAs (Crossed-Linked Enzyme Aggregates) was used as biocatalyst. In the continuous batch process for RBBR decolorization, acyltransferase E-CLEAs (Encapsulated CLEAs with polyvinyl alcohol) could be recycled at least 6 times.

Simultaneous Decolorization of Methyl Red and Generation of Electricity in Microbial Fuel Cell by Bacillus circulans NPP1

This study examined azo dye methyl red decolorization in a 2 chambered microbial fuel cell (MFC). The primary objectives of the study were to construct MFC and evaluate methyl red decolorizing and degrading bacterium Bacillus circulans potential in simultaneous decolorization and electricity generation process. In MFC, both the chambers were connected by Nafion 117 Proton exchange membrane and Graphite electrodes were placed in cathode and anode chamber for optimum electron transfer performance in open circuit system. Under an optimal condition 98% methyl red (300 ppm) decolorization, 9.9 mg/l/h maximum decolorization rate and 856 mW/m2 maximum power densities were achieved. As compared to traditional anaerobic technology higher decolorization and electricity generation efficiency was achieved by MFC. Bacillus circulans is electrogenic bacteria having potential in MFC technology.

Influence of &lt;i&gt;Gigantochloa ligulata&lt;/i&gt; Nutrient on &lt;i&gt;Lactobacillus delbrueckii&lt;/i&gt; for Textile Wastewater Decolorization

Water pollution due to the discharges of textile wastewater without treatment is the most concern problem identified. This reduces the degree penetration of sunlight into the water. It causes some human health problem such as bladder cancer, liver cancer and splenic tumor. The biological research using Lactobacillus bacteria was developed to reduce the environment problems. This research was studied on the impact of Lactobacillus delbrueckii on decolorization of textile wastewater enhanced by Gigantochloa ligulata nutrient. This nutrient contains high protein, mineral, moisture and carbohydrate such as fructose, glucose and sucrose. Those nutrients are used by Lactobacillus species to produce lactic acid, which simultaneously help in decolorizing textile wastewater. The effect studies; Lactobacillus delbrueckii dosage (4, 7, 10 mL/mL), agitation speed (1, 75.5, 150 rpm) and dye concentration (0.1, 0.55, 1.0 mL/mL) were performed to determine the rate of decolorization for every 24 hours. The result obtained show the maximum decolorization rate, 65.30% occurs at 7.66 mL of Lactobacillus dosage and 0.49 mL/mL of dye concentration with 64.20 rpm. It can be concluded that Gigantochloa ligulata nutrient has potential in enhancing Lactobacillus species to decolorize of textile wastewater.

Aqueous thermostabilization of Pleurotus florida NCIM 1243 laccase and its potential application in Acid Black 10BX dye decolorization: process optimization

In the present investigation, aqueous stabilization of laccase from Pleurotus florida (NCIM 1243) at high temperatures using polysaccharide additives for decolorization of Acid Black 10BX was reported. The stabilization experiments suggest that the combinatorial effect of pectin and carrageenan improved the enzyme stability as compared as individual additives. Hence, combination of pectin and carrageenan were selected to construct an appropriate Response surface methodology (RSM) to enhance the enzyme stability in acidic solutions. Additionally, pH value was taken as a variable to optimize the polysaccharide additives. The optimum values of variables obtained for maximum laccase stabilization at higher temperature are pectin, 0.31%, carrageenan, 0.3% and pH, 4.4 with predicted percentage residual activity of 93.77%. The experimental validation of laccase stabilization was found to be 90.8% using optimized variables. Furthermore, the series of enzymatic dye decolorization experiments were performed to obtain optimum process parameters for maximum decolorization efficiency. Various process parameters such as enzyme concentration (10U/ml), dye concentration (10mg/l), temperature (25°C) and reaction time (150min) were successfully optimized to achieve maximum decolorization rate. Results of the experimental data reveled that stabilized laccase has the great potential for Acid Black 10BX decolorization at 60°C than that of native enzyme at pH, 4.4. This investigation enlighten that pectin and carrageenan plays an important role in laccase stabilization and its low cost found to be a good support for large-scale application in biodegradation process.