Search results

This paper aims to evaluate the bioremediation [chemical oxygen demand (COD) and color removal] of the effluent from the cardboard recycling industry in Yazd, central province of Iran, using mixed fungal culture.

First, the effluent samples from the cardboard recycling industry were cultured on potato dextrose agar medium to isolate native fungal colonies. The grown colonies were then identified using morphological macroscopic and microscopic characteristics to choose the dominant fungi for bioremediations. The mixed cultures of Aspergillus niger, Aspergillus flavus and Penicillium digitatum were finally used for bioremediation experiments of the cardboard recycling industry. A suspension containing 1 × 10⁶ CFU/ml of fungal spores was prepared from each fungus, separately and their homogenous mixture. Sewage samples were prepared and sterilized and used at 25%, 50% and 90% dilutions and pH levels of 5, 7 and 8 for bioremediation tests using mixed fungal spores. Following that, 10 ml of the mixed fungal spores were inoculated into the samples for decolorization and COD removal and incubated for 10 days at 30°C. The amount of COD removal and decolorization were measured before incubation and after 3, 6 and 10 days of inoculation. In this research, the color was measured by American Dye Manufacturer Institute and COD by the closed reflux method. The results of the present study were analyzed using SPSS 21 statistical software and one-way ANOVA tests at p-value < 0.05.

The results of this research showed that the mean decolorization by mixed fungal culture over 10 days at pH levels of 5, 7 and 8 were 44.40%, 45.00% and 36.84%, respectively, and the mean COD removal efficiency was 71.59%, 73.54% and 16.55%, respectively. Moreover, the mean decolorization at dilutions of 25%, 50% and 90% were 45.00%, 31.93% and 30.53%, respectively, and the mean COD removal efficiency was 73.54%, 62.38% and 34.93%, respectively. Therefore, the maximal COD removal and decolorization efficiency was obtained at dilution of 25% and pH 7.

Given that limited studies have been conducted on bioremediation of the effluent from the cardboard recycling industry using fungal species, this research could provide useful information on the physicochemical properties of the effluent in this industry.

Indirect electrochemical oxidation and electro-flocculation were combined to degrade indigo wastewater.

The degradation efficiency of indigo wastewater in single-cell and double-cell were investigated. Based on the previous single factor experiments, the oxidative degradation conditions of indigo wastewater in single cell were optimized by response surface methodology (RSM). The decolorization rate, chemical oxygen demand (COD) removal rate, the contents of flocculation precipitation and indigo were measured and analyzed.

The degradation efficiency in single cell was higher than in double cell. The electrolysis conditions were optimized by RSM and the decolorization rate was 99.01% with COD removal rate of 60.34% and conductivity of 89.75 mS/cm. The amount of flocculated precipitation decreased by 53.33% and the indigo increased by 86.34%. The content of Na and S decreased by 12.13 and 6.49%, respectively. The ratio of Fe3+ to Fe2+ in the solution was 4.62:1, indicating that most of the iron dropped on the electrode sheet was converted to Fe3+.

The one-step electrochemical oxidation and flocculation method with the advantages of simple operation and environmental protection, provided a reference for the actual treatment of dyeing wastewater.

Combining the electrochemical flocculation and oxidation provided an efficient and practical solution for degradation of indigo wastewater.

Combining the advantages of electrochemical oxidation and electroflocculation, the application of electrochemistry in printing and dyeing wastewater treatment technology has been expanded.

Among various metal oxide nano particles, MgO NPs and ZnO nanoparticles (NPs) in particular are gaining increasing attention due to their multifunctional characteristics, low cost and compatibility with textile materials. Each type of nanoparticle excels over others in certain properties. As such, it is often crucial to carry out comparative studies of NPs to identify the one showing higher efficiency/output for particular applications of textile products.

In the investigation reported in this paper, ZnO NPs and MgO NPs were synthesised via sol-gel technique and characterised. For comparative analysis, the synthesised NPs were evaluated for multiple properties using standard procedures before and after being applied on cotton fabrics by a dip-pad-dry-cure method.

XRD and FTIR analyses confirmed the successful synthesis of ZnO and MgO NPs. Homogeneous formation of desired NPs and their dense and uniform deposition on the cotton fibre surface were observed using SEM. ZnO NPs and MgO NPs coatings on cotton were observed to significantly enhance self-cleaning/stain removal properties achieving Grade 5 and Grade 4 categories, respectively. In terms of ultraviolet (UV) protection, ZnO or MgO NP coated fabrics showed UPF values of greater than 50, i.e. excellent in blocking UV rays. MgO NPs exhibited 20% cleaning efficiency in treating reactive dye wastewater against ZnO NPs which were 4% efficient in the same treatment, so MgO was more suitable for such type of treatments at low cost. Both NPs were able to impart multifunctionality to cotton fabrics as per requirement of the end products. However, ZnO NPs were better for stain removal from the fabrics while MgO NPs were appropriate for UV blocking.

It was therefore clear that multifunctional textile products could be developed by employing a single type of cost effective and efficient nano particles.

In this study, the oxidative degradation performance of indigo wastewater based on electrochemical systems was explored. The decolourization degrees, removal rate of chemical oxygen demand and biochemical oxygen demand of the indigo wastewater after degradation were evaluated and optimized treatment conditions being obtained.

The single factor method was first used to select the electrolyte system and electrode materials. Then the response surface analysis based on Box–Behnken Design was chosen to determine the influence of four independent variables such as FeCl₃ concentration, NaCl concentration, decolourization time and voltage on the degradation efficiency.

On the basis of single factor experiment, the electrode material of stainless steel was selected in the double cell, and the indigo wastewater was electrolyzed with FeCl₃ and NaCl electrolytes. The process conditions of electrochemical degradation of indigo wastewater were optimized by response surface analysis: the concentration of FeCl₃ and NaCl was of 16 and 9 g/L, respectively, with a decolourization time of 50 min, voltage of 10 V and decolourization percentage of 98.94. The maximum removal rate of chemical oxygen demand reached 75.46 per cent. The highest ratio of B/C was 3.77, which was considered to be more biodegradable.

Dyeing wastewater is bringing out more and more pollution problems to the environment. However, there are some shortcomings in traditional technologies such as adsorption and filtration. As a kind of efficient and clean water treatment technology, electrochemical oxidation has been applied to the treatments of various types of wastewater. The decolourization and degradation of indigo wastewater is taken as an example to provide reference for the treatment of wastewater in actual plants.

The developed method provided a simple and practical solution for efficiently degrading indigo wastewater.

The method for the electrochemical oxidation technology was novel and could find numerous applications in the degradation of printing and dyeing wastewater.

This study aims to explore suitable anode materials used in the electrochemical system for indigo dyeing wastewater, to achieve optimal treatment performances.

The single factor experiment was used to explore the optimum process parameters for electrochemical decolorization of indigo dyeing wastewater by changing the applied voltage, electrolysis time and electrolyte concentration. At the voltage of 9 V, the morphology of flocs with different electrolytic times was observed and the effect of electrolyte concentration on decolorization rate in two electrolyte systems was also investigated. Further analysis of chemical oxygen demand (COD) removal rate, anode weight loss and sediment quantity after electrochemical treatment of indigo dyeing wastewater were carried out.

Comprehensive considering the decolorization degree and COD removal rate of the wastewater, the aluminum electrode showed the best treatment effect among several common anode materials. With aluminum electrode as an anode, under conditions of applied voltage of 9 V, electrolysis time of 40 min and sodium sulfate concentration of 6 g/L, the decolorization percentage obtained was of 94.59% and the COD removal rate reached at 84.53%.

In the electrochemical treatment of indigo dyeing wastewater, the aluminum electrode was found as an ideal anode material, which provided a reference for the choice of anodes. The electrodes used in this study were homogenous material and the composite material anode needed to be further researched.

It provided an effective and practical anode material choice for electrochemical degradation of indigo dyeing wastewater.

Combined with the influence of applied voltage, electrolysis time and electrolyte concentration and anode materials on decolorization degree and COD removal rate of indigo dyeing wastewater, providing a better electrochemical treatment system for dyehouse effluent.

Five different structural reactive dyes (Reactive Brilliant Blue K-3R, Everacion Blue H-ERD, Moderzol Blue FBR, Atuzol Black B and Moderzol Blue HEGN) were treated with laccase (Denilite II US) in order to determine the optimum decolouration conditions. The experiments showed that laccase had distinct decolouration effects on these five dyes. Under optimum conditions, the colour removal rates of Everacion Blue H-ERD and Moderzol Blue HEGN were over 90%. Furthermore, the effects of different additives, such as acid ion, metal ion, and surfactants on the decolouration rate of Reactive Brilliant Blue K-3R were discussed. The results show that the decolouration rate is significantly promoted through the addition of Cu²⁺ and Al³⁺, while it is inactivated with Fe²⁺ and ion surfactants. Moreover, the COD removal rates of the five dyes are more than 75%.

In this study, the removal of a series of acid dyes by hybrid polymer adsorbent was investigated. Textile industry wastewater is mainly consisted of suspended solid particles and organic compounds with complex and nondecomposable structures. Treatment of such wastewaters has received much attention by researchers because of high water consumption and the presence of various chemical compounds, especially dyes. The use of polymers has recently attracted much attention for the treatment of textile wastewaters. According to the literature, hybrid polymers are highly capable of adsorbing dyes. In this research work, polyacrylamide/iron sulfate (PAM-FeSO₄) hybrid polymer was successfully synthesized through solution polymerization of acrylamide with ammonium persulfate and sodium thiosulfate and gradual addition of iron sulfate. The hybrid polymeric adsorbent was then used for removing acidic dyes with different chemical structures.

The effects of various experimental conditions and parameters, such as initial concentrations of dye and adsorbent, on the adsorption capacity of the adsorbent were investigated. The dye concentration was measured by an UV–vis spectrophotometer. The adsorption equilibrium was studied by plotting adsorption isotherms. The experimental data was fitted to Langmuir and Freundlich isotherms.

The adsorption experiments indicated that the PAM-FeSO₄ hybrid polymer has a high adsorption capacity (117.64 mg g⁻¹ for the Orange ІІ and 80.64 mg g⁻¹ for the Sunset Yellow [SY]) when 80 mg of adsorbent was immersed in the dye solution (1 g L⁻¹) with a pH of 11 at 25°C. The analysis of the equilibrium isotherms using the Langmuir and Freundlich isotherms indicated that the Langmuir model fit well to the experimental data.

To the best of the authors’ knowledge, this study is original. The removal of acid dyes such as Sunset Yellow and Methyl Orange using PAM-FeSO₄ hybrid polymer as flocculant was done for the first time.

The purpose of this paper is to investigate the electrochemical treatment of textile dye wastewater in the presence of NaCl electrolyte by using aluminium electrodes.

The electrochemical treatment of textile dye wastewater was optimized using response surface methodology (RSM). RSM‐based D‐optimal design was employed to construct statistical models relating turbidity and designed effective parameters known as current density, electrolyte concentration and electrolysis time. The experimental plan consists of a three‐factor (three numerical) matrix.

The results show that the current density has significant effect on the reduction of turbidity. Besides, electrolysis time is the most influential factor on the turbidity. In order to enhance the electrochemical treatment performance, no coagulant addition or further physicochemical processes were employed.

Industrial certain textile dye wastewater in Turkey is used to determine optimal values.

This paper aims to introduce two methods for immobilisation of TiO₂ nanoparticles on a glass plate by means of silicon resin as a medium. Then, to ensure the effectiveness of these stabilisation methods, the photocatalytic degradation and mineralisation of the dye C.I. Reactive Blue 21 (RB21), as a model organic pollutant, were compared using these immobilised systems and the suspended one utilizing UV and sunlight irradiations individually.

TiO₂ nanoparticles were supported onto a glass support by silicon resin as an adhesion agent by spraying of TiO₂ nanoparticles on the resin surface, which covered the glass plate or brushing the mixture of TiO₂ and the resin onto the glass. The characteristics of the applied nano-TiO₂ were investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and Brunauer

Emmett–Teller. Photocatalytic degradation and mineralisation of C.I. Reactive Blue 21 (RB21) by two immobilised systems were compared with suspended system in a batch mode under UV and sunlight irradiations after 2 h of treatment.

The results showed that these immobilised modes had efficiencies, including 82-87 per cent degradation of RB21 and 52-58 per cent decrease in chemical oxygen demand (COD) for the operational time of 120 min, comparable to that of the suspended mode (91 per cent degradation of RB21 and, consequently, COD is decreased by 65 per cent). Comparison between photocatalytic efficiencies of two immobilised systems revealed that coating by spraying method performed better than brushing one due to more available surface area of TiO₂. Finally, the results obtained from the mentioned supported systems under sunlight indicated the efficiencies about 87 to 89 per cent in comparison of the suspension system regardless of the reaction time enhancement up to 15 h compared to the UV irradiation.

In this research, the fixation of TiO₂ nanoparticles on a substrate such as normal glass by an easy, inexpensive, durable, repairable and repeatable technique for wastewater treatment was introduced. Due to the simplicity and cheapness of these stabilisation methods and as these stabilisation methods are applicable on other substrates such as concrete, ceramics, etc., you can use these methods in major scales for purification of contaminated water, for example for stabilisation of TiO₂ nanoparticles on wall pool utilized for water purification can be used.

Two introduced immobilisation methods in this study are novel. The photocatalytic efficiency of these immobilised systems in degradation of water contaminants was investigated by using these systems in degradation and mineralisation of the dye C.I. Reactive Blue 21 (RB21), as a model organic pollutant compared with same TiO₂ nanoparticles in an aqueous suspension system under UV light. Furthermore, this paper investigated replacing of inexpensive sources of UV light instead of UV lamps, and then the same photocatalytic reactions were carried out under sunlight as a UV source and degradation efficiencies by two UV sources were compared.

The purpose of this paper is to analyze nano zero-valent iron (nZVI)-activated carbon/Nickel (nZVI-AC/Ni) by a novel method. The synthesized adsorbent was used to degrade reactive orange 16 (RO 16) azo dye.

The optimum conditions for the highest removal of RO 16 dye were determined. Characterization of nZVI-AC/Ni was done by scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction and energy-dispersive X-ray spectroscopy. The nZVI-AC/Ni were used for the removal of dye RO 16 and the parameters affecting were discussed such as pH, adsorbent dosage, contact time and concentration of dye. To investigate the variables and interaction between them, an analysis of variance test was performed.

The characterization results show that the synthesis of nZVI-AC/Ni caused no aggregation of nanoparticles. The maximum dye removal efficiency of 99.45% occurred at pH 4, the adsorbent dosage = 0.1 gL-1 and the dye concentration of 10 mgL-1. Among various algorithms of feed-forward backpropagation neural network, Levenberg–Marquardt with mean square error (MSE) = 9.86 × 10^–22 in layer = 5 and the number of neurons = 9 was selected as the best algorithm. On the other hand, the MSE of the radial basis function model was 0.2159 indicating the good ability of the model to predict the percentage of dye removal.

There are two main innovations. One is that the novel nZVI-AC/Ni was prepared successfully. The other is that the optimized conditions were obtained for the removal of RO 16 dye from an aqueous solution. Furthermore, to the best of the knowledge, no study has ever investigated the removal of RO 16 by nZVI-AC/Ni produced.