Degradation Of Real Textile Wastewater Research Articles

Ozone Assisted Photocatalytic Degradation of Textile Wastewater

In present research, photocatalytic degradation of textile wastewater was investigated through the combined effect of ozonation and photocatalysis processes. Catalytic acids in the nano-particle form under moderate reaction conditions were used for the successful disintegration of contaminants in textile wastewater which in turn increases the process efficiency. Moreover, the combined effect of the photocatalytic-ozonation process after secondary treatment of textile wastewater on discharge requirements of zero discharge hazardous chemicals (ZDHC) by Road to Zero was also studied. Different parameters were optimized like ozone flowrate, catalytic concentration, UV light intensity, and reaction time. Results revealed that overall process efficiency is influenced by ozone and reaction time. In contrast, an increased rate of degradation is attributed to the synthesized TiO2 (anatase) in nanoparticle form. The combined ozone-assisted photo-catalytic process showed the COD, BOD, and TSS removal efficiencies of 91.5%, 94%, and 86% at 25 and#176;C temperature and pH 7-9. The results were attained at optimum conditions like reaction time (140 min), Ozone concentration (2 g/hr), TiO2 concentration (2g/L), and UV energy (88 W), respectively. The study demonstrated the efficiency of an integrated process for the degradation of real textile wastewater. Thus, combined photocatalytic and ozonation processes are known to exhibit better responses than individual processes for pollutants removal from textile wastewater.

Electro-Fenton mineralization of real textile wastewater by micron-sized ZVI powder anode.

The diverse compositions and complex nature of the textile wastewater make it imperative to find an economical and suitable degradation pathway. The degradation of real textile wastewater on a novel heterogeneous electro-Fenton system was carried out with a composite anode of magnetically fixed micron ZVI coupling with a Ti/RuO2-IrO2 sheet. The influences of different variables such as mZVI dosage, H2O2 amount, applied voltage and pH value on both total organic carbon and chemical oxygen demand removal efficiencies and energy consumption were investigated. The optimized parameters were simultaneously verified by using electrochemical workstation Tafel curves and Nyquist plots. The optimal operating conditions for evaluating the wastewater treatment were H2O2 dosage of 0.10 mol·L-1, applied voltage of 5.0 V, mZVI amount of 1.0 g·L-1 and initial pH value of 3.0. The high TOC and COD removal efficiencies of 92.44 and 82.84% could be achieved simultaneously in 60 min, respectively. XRD, XPS and SEM-EDS were used to investigate the interaction between the pollutant and the mZVI. GC-MS analysis was performed on untreated and treated wastewater to determine the degradation of pollutants in dyeing wastewater during the electro-Fenton process and to effectively propose a suitable degradation mechanism for this system.

Investigation of Basalt Properties as Heterogeneous Catalyst for Fenton Oxidation of Textile Wastewater

AbstractIn this study, basalt is used as a catalyst for the removal of the dyes malachite green (MG) and crystal violet (CV) from aqueous solution. First, the effect of sintering temperature on Fenton process is optimized using basalt powder. Different analysis techniques such as X‐ray diffraction (XRD), X‐ray fluorescence (XRF), Brunauer‐Emmett‐Teller (BET), and Fourier‐Transform Infrared Spectroscopy (FTIR) are used to characterize basalt powder. It is concluded that Fe2O3 in basalt powder is the main component responsible for the degradation of dyes in the Fenton process. The maximum degradation of the dyes (97.02% for CV and 95.71% for MG) is obtained at 10 mg L−1 dye concentration, solution pH of 6, 1 g L−1 catalyst amount, and 12 mm H2O2 concentration for 2 h. The results are fitted to the second‐order kinetic model. The reusability of the catalyst is explored, and the basalt showed stability in the removal efficiency for repeated five cycles. The degradation of real textile wastewater is also studied. The removal efficiency reached up to 60.33% at optimum conditions of pH 2, basalt amount of 5 g L−1, H2O2 concentration of 400 mm. The results showed that the basalt powder is successfully utilized as a heterogeneous catalyst for textile wastewater treatment.

A comparative study of photo-Fenton process assisted by natural sunlight, UV-A, or visible LED light irradiation for degradation of real textile wastewater: factorial designs, kinetics, cost assessment, and phytotoxicity studies

The present work aims to evaluate the treatment of the effluent from the textile industry via advanced oxidative processes of photo-Fenton assisted by different sources (natural sunlight, UV-A or visible LED lamps). To identify the best operating conditions, a factorial design was carried out for each process. It was observed that after the optimization of the processes, chemical oxygen demand (COD) removals greater than 88% were achieved. In addition, it was observed that the use of the LED lamp required lower reagent concentrations compared to solar and UV-A sources. A kinetic study was carried out under the best conditions obtained and it was observed that the sources showed rapid evolution, reaching a COD removal equilibrium with 30 min of reaction. Reagent monitoring was also carried out, and it was observed that they were not limiting to the reaction. Phytotoxicity analysis was also satisfactory since the treated effluents allowed a higher relative growth and germination index of the cucumber roots compared to the raw effluent. Finally, the cost analysis indicated that the use of LED lamps resulted in a reduction in electrical consumption compared to the UV-A lamp, as well as a reduction in the cost of reagents due to the lower concentration of reagents required compared to processes assisted by natural sunlight and UV-A.

Application of a novel rGO-CuFeS2 composite catalyst conjugated to microwave irradiation for ultra-fast real textile wastewater treatment

The disposal of wastewater containing large amounts of dyes is a public health and environmental problem, due to its toxicity into the aquatic biota, the reduction in sunlight penetration, which consequently interference in photosynthetic activity. In the present study a new composite, based on the heterojunction of reduced graphene oxide (rGO) and chalcopyrite (CuFeS2), was developed to treat a real textile wastewater (RW). The efficiency of the composite assisted by microwave irradiation was evaluated to catalyze the decolorization and degradation of RW containing a high concentration of the azo Direct Black 22 (DB22). A small amount (0.5 w/w%) of rGO on CuFeS2 was enough to uplift the efficiency of decolorization to 74 % of DB22 and 97 % TOC in the RW, only in the first min of treatment, and 97 % and 99 %, respectively, at 6 min. The improvement in catalytic activity can be attributed to the dipolar polarization effect, hot spots and the generation of hydroxyl radicals. Additionally, a synergistic effect between the composite and microwave irradiation, assisted by hydrogen peroxide, reduced the RW phytotoxicity, improving the radicle length of Lactuca sativa three times (from 0.87 cm to 2.65 cm with the application of a single minute of treatment). The reduction in phytotoxicity led to an increase in the germination percentage from 36 % to 53 %. Finally, the use of MW irradiation coupled to a novel rGO-CuFeS2 composite, in presence of H2O2 under acid medium, provides a feasible and highly rapid method to treat RW, reducing its phytotoxicity.Capsule: A novel rGO-CuFeS2 catalyst was developed and applied together with microwave irradiation for an ultra-fast degradation treatment (6 min) in real textile wastewater.

Photocatalytic degradation of real textile wastewater using carbon black-Nb2O5 composite catalyst under UV/Vis irradiation

ABSTRACT This work investigated the impregnation of Nb2O5 into carbon black (CB) in different ratios and its effect in photocatalytic degradation of real wastewater from a dyeing factory by advanced oxidative processes (AOP). Synthesized catalysts were characterized regarding their crystalline structure (DRX, micro-Raman), morphology (MEV), textural (BET area) and optical properties (bandgap energy by diffuse reflectance) and pH at the point of zero charge (pHpzc). Preliminary tests showed better photodegradation results in the acidic medium after 5 h of irradiation with NCB-0.5 (Nb2O5:CB 0.5:1). Treatment parameters optimization was carried out using response surface methodology based on Box–Behnken experimental design. Catalyst concentration, solution pH and irradiation time were varied, analysing absorbance reduction (285 and 574 nm), COD and TOC removal after treatment as responses. The composite catalyst showed improved photocatalytic activity, attributed to an increase in adsorption capacity and the bandgap narrowing, redshifting the absorption edge wavelength to the visible region, brought by CB impregnation. Optimal conditions were found at 0.250 g L−1 of catalyst, pH 2.0 and 5 h of irradiation, removing 72.19% and 93.52% of absorbance in 285 and 574 nm, respectively, 51.29% of COD and 70.70% of TOC using NCB-0.5.

Textile Wastewater Treatment by Peroxydisulfate/Fe(II)/UV: Operating Cost Evaluation and Phytotoxicity Studies

The discharges of the wastewater from the textile industry generate a substantial quantity of effluents which can cause various environmental problems, if disposed of without any prior treatment. Therefore, the treatment of these textile effluents is necessary. The present study aims to investigate the removal efficiency of colors from wastewater containing mixed primary direct dyes and real textile industry wastewater using PDS (Peroxydisulfate)/Fe(II)/UV process. A simulated mixture, based on an industrial recipe and containing Reactive Yellow 17 (RY17), Reactive Red 120 (RR120), and Reactive Blue 19 (RB19), was investigated. The obtained results showed that the mineralization rate is around 96.1% for RY17, 99.2% for RR120, 100% for RB19 and 80% for their mixed during 2 h of the treatment. The degradation of real textile wastewater was about 66% under similar conditions. The evaluations showed that ~ 93.82 MAD/m3 (~ 8.64 EURO/m3) is needed to supply the operating cost. As a vital industrial criterion, it was estimated that the conditions of initial pH of 3, [PDS] = 1 mM and T = 25 °C the highest cost effective case of the process for degrading the mixed dyes. Phytotoxicity studies revealed that the degradation products of mixed dyes and textile effluent were scarcely toxic in nature, thereby increasing the applicability of PDS/Fe(II)/UV for the treatment of textile wastewater. This will open a perspective for the reuse of treated water in crop irrigation. Based on the results of the advanced oxidation technologies experiments, it was found that PDS/Fe(II)/UV is the best treatment method for real textile wastewater.

Engineering aspects of catalytic ozonation for purification of real textile industry wastewater at the pilot scale

Present study investigated the development and use of copper-doped zinc oxide as catalysts to facilitate degradation of real textile wastewater by ozonation. Effect of various operating parameters like catalyst dosage, pH, and ozone dosage was examined. The Cu-doped ZnO removes 89% of COD within 30min of reaction whereas tertiary-butyl alcohol inhibited COD reduction at 10mM concentration under the optimised conditions, indicating that catalytic ozonation follows hydroxyl (OH) radical method for COD reduction. MATLAB ODE45 function was used to draw kinetic plots where catalytic ozonation shows six times higher rate constant. Catalytic ozonation has been successfully implemented at pilot-scale.

Influence of PVP surfactant on the morphology and properties of ZnO micro/nanoflowers for dye mixtures and textile wastewater degradation

Flower-like ZnO micro/nanostructures were successfully prepared using a polyvinylpyrrolidone (PVP)-assisted co-precipitation route and characterized by X-ray diffraction (XRD), field emission-scanning electron microscopy (FESEM), energy dispersive X-ray (EDX), transmission electron microscopy (TEM), fourier transform infrared (FTIR) and photoluminescence (PL) spectroscopy. Smaller sizes of ZnO micro/nanoflowers were synthesized with different amounts of PVP as surfactant. Possible morphology evolution and formation mechanism of the flower-like micro/nanostructures were postulated. Concentrations of PVP in the reaction mixtures served as key role for morphology-controlled synthesis of ZnO as PVP can assist the oriented crystal growth during the synthesis. The as-synthesized ZnO samples prepared at 12.5 mg/mL PVP displayed higher photoactivity for the simultaneous degradation of methyl orange and methyl green mixtures. The photocatalytic tests also indicated that process parameters such as the initial dye concentration and solution pH exerted their individual influences on the dye mixtures degradation. Under determined experimental conditions, 94.1% chemical oxygen demand (COD) removal of dye mixtures was attained after 240 min of reaction. The ZnO photocatalytic degradation of real textile wastewater was then evaluated and a lower COD removal efficiency (∼75%) was observed at similar treatment duration. Other real textile wastewater quality parameters of biochemical oxygen demand (BOD5), turbidity, total suspended solid (TSS), colour, ammoniacal nitrogen (NH3-N) and pH were also investigated.

Performance analysis of a continuous serpentine flow reactor for electrochemical oxidation of synthetic and real textile wastewater: Energy consumption, mass transfer coefficient and economic analysis

A continuous flow electrochemical reactor was developed, and its application was tested for the treatment of textile wastewater. A parallel plate configuration with serpentine flow was chosen for the continuous flow reactor. Uniparameter optimization was carried out for electrochemical oxidation of synthetic and real textile wastewater (collected from the inlet of the effluent treatment plant). Chemical Oxygen Demand (COD) removal efficiency of 90% was achieved for synthetic textile wastewater (initial COD - 780 mg L−1) at a flow rate of 500 mL h−1 (retention time of 6 h) and a current density of 1.15 mA cm−2 and the energy consumption for the degradation was 9.2 kWh (kg COD)−1. The complete degradation of real textile wastewater (initial COD of 368 mg L−1) was obtained at a current density of 1.15 mA cm−2, NaCl concentration of 1 g L−1 and retention time of 6 h. Energy consumption and mass transfer coefficient of the reactions were calculated. The continuous flow reactor performed better than batch reactor with reference to energy consumption and economy. The overall treatment cost for complete COD removal of real textile wastewater was 5.83 USD m−3.

Fe3+ doped TiO2 nanotubes for combined adsorption–sonocatalytic degradation of real textile wastewater

Fe-doped titanium dioxide (TiO2) nanotubes catalyst with large specific surface area and low band gap energy were successfully synthesized using sol–gel followed by hydrothermal method. The activity of the catalyst was assessed by examining the treatment of real textile wastewater through combined adsorption and heterogeneous sonocatalysis. Fe-doped TiO2 nanotubes exhibited better removal efficiency in the case of pre-adsorption followed by sonocatalytic reaction as compared to the simultaneous adsorption and sonocatalysis system. Pre-adsorption on TiO2 nanotubes was found to promote sonocatalytic degradation and the latter process could be considered as a surface-catalyzed reaction. Effect of the solution pH (3–11), catalyst dosage (2–10g/L) and hydrogen peroxide (H2O2) dosage (20–80mM) on the adsorption–sonocatalysis for the treatment of a real textile wastewater were investigated in detail. The best degradation efficiency can be achieved at solution pH of 3, 6g/L of Fe-doping, 40mM of H2O2, an ultrasonic frequency of 35kHz and an output power of 50W after 1h of adsorption followed by 3h of ultrasonic irradiation under continuous aeration. The color, COD and TOC removals were 79.9%, 59.4% and 49.8%, respectively. In short, adsorption followed by sonocatalytic degradation in the presence of Fe-doped TiO2 nanotubes showed great potential for efficient treatment of real textile wastewater.

Photocatalytic degradation of methylene blue dye from aqueous solution using silver ion-doped TiO2 and its application to the degradation of real textile wastewater

Methylene blue dye (MB) was degraded photocatalytically in aqueous solution using Ag+ doped TiO2 under UV irradiation. The degradations of the dye using untreated TiO2 and Ag+ doped TiO2 were compared. Ag+ doped TiO2 was found to be more efficient. Using Ag+ doped TiO2 the filtration process was eliminated, as the particles became more settleable. The effect of various parameters such as catalyst loading, initial dye concentration, depth of solution, degree of adsorption, pH and O2 on dye degradation was studied. The extent of mineralization was studied by observing the COD removal at different time intervals. The effects of various interfering ions such as Cl−, NO3 −, CO3 2−, SO4 2−, Ca2+ and Fe3+ and electron acceptors such as H2O2, KBrO3 and (NH4)2S2O8 on the dye degradation was also studied. The degradation kinetics fitted well to Langmuir-Hinshelwood pseudo first order rate law. An aqueous solution of MB (20ppm) degraded by more than 99% after UV irradiation for 180 min with Ag+ doped TiO2 (2 g/L) and by more than 95% with untreated TiO2 (2 g/L). The COD removal was more than 91% with Ag+doped TiO2 and more than 86% with untreated TiO2 after 240 min. The degradation and COD removal of 5 times diluted textile wastewater was more than 98% and 79% respectively with 1 g/L Ag+ doped TiO2 after UV irradiation for 420 min.

Photo-assisted electrochemical degradation of real textile wastewater

In the present study, photo-assisted electrochemical degradation of real textile wastewater was performed. Degradation assays were performed at constant current (40 mA cm(-2)) in a combined electro/photochemical flow-cell using a Ti/Ru(0.3)Ti(0.7)O(2) DSA type electrode. The results show that the method is capable of removing color and chemical oxygen demand (COD) from the effluent. Additionally, the effect of initial pH and type of supporting electrolyte (Na(2)SO(4) or NaCl) was investigated. The principal figures of merit used in this study were COD removal and color removal (605 nm). The results show that up to 72% color and up to 59% COD removal in 120 min is possible under the operating conditions employed. Studies of the phytotoxicity of the wastewater before and after the photo-assisted degradation assays are also presented and the results demonstrate that the toxicity of the effluent is dependent on the length of electrolysis time and the treatment procedure employed.