Treatment Of Synthetic Textile Wastewater Research Articles

Joint Multi-Optimization of an Extremophilic Microbial Bioanode for Mitigation of Mixed Hazardous Azo Dyes in Textile Synthetic Wastewater

Bioelectrochemical systems (BESs), rather than physicochemical processes, are used for wastewater remediation, electricity production, and zero carbon dioxide emission. Textile effluents contain organic and inorganic compounds that can fuel BESs. The main goal of this study was to understand the interplay between the anode material, its surface area, the potential applied to the working electrode (WE), and the concentration of the co-substrate, and how these factors lead to the formation of highly efficient thermohalophilic bioanodes (THB) retrieved from Chott El Djerid (SCD) hypersaline sediment for the treatment of synthetic textile wastewater. To this end, twenty-seven bioanode formation experiments were designed using a Box-Behnken matrix and response surface methodology to understand concomitant interactions. All experiments were conducted in electrochemical reactors of final volume 750 mL inoculated with 80% of enrichment medium containing three azo dyes at a concentration of 300 ppm and 20% of biocatalyst microbial SCD source, at 45 °C. The optimal levels were predicted using NemrodW software as carbon felt (CF) anode material, 6 cm2 anode surface, 7 g/L glucose concentration, and −0.1 V applied potential. These theoretical results were experimentally validated, using maximum current output of 5.23 ± 0.30 A/m2, decolorization rate of 100%, and a chemical oxygen demand (COD) removal rate of 96 ± 1%. Illumina Miseq results revealed that bacterial community harbored the bioanode was dominated at phylum level by Firmicutes (67.1%). At the species level, the biofilm was mainly colonized by Orenia metallireducens species (59.5%). Obtained findings show a promising application of THB in the degradation of recalcitrant molecules as well as for the energy recovery.

Treatment of synthetic textile wastewater containing Acid Red 182 by electro-Peroxone process using RSM

The Azo dyes are primarily utilized in textile industries. Treatment of textile wastewater because of the presence of recalcitrant dyes using conventional processes is greatly challenging and ineffective. So far, no experimental work has been conducted on the decolorization of Acid Red 182 (AR182) in aqueous media. Hence, in this novel experimental work, the treatment of AR182 from the Azo dyes family was explored using the electro-Peroxone (EP) process. For the optimization of operating factors, including AR182 concentration, pH, applied current, and O3 flowrate in the decolorization of AR182, Central Composite Design (CCD) was utilized. The statistical optimization presented a highly satisfactory determination coefficient value and a satisfactory second-order model. The expected optimum conditions by the experimental design were as the following: AR182 concentration at 483.12 mg.L−1, applied current at 0.627,113 A, pH at 8.18284 and O3 flowrate at 1.13548 L min−1. The current density is directly proportional to dye removal. However, increasing the amount of applied current beyond a critical value has a contradictory impact on dye removal performance. The dye removal performance in both acidic and highly alkaline environments was negligible. Hence, ascertaining the optimum pH value and conduction of the experiment at that point is critical. At optimum points, the decolorization performance in predicted and experimental conditions for AR182 were 99 and 98.5%, respectively. The outcomes of this work clearly substantiated that the EP can be successfully utilized for the decolorization of AR182 in textile wastewater.

Electrocoagulation process for the decolorization of wastewater containing Reactive Red 195 and CFD simulation of the hydrodynamic in a continuous-flow single-channel reactor

Abstract The highly colored textile effluents require efficient treatment before being released into the environment. In this study, a continuous-flow single-channel reactor operating in closed- circuit was used to apply electrocoagulation for the treatment of synthetic textile wastewater. First, the characterization of the hydrodynamic within the reactor is evaluated by Computational Fluid Dynamics simulation using the k-ε turbulence model (Comsol Multiphysics®). Apart from a non-uniform distribution of the velocities inside the reactor, no particular anomaly was observed. Second, the decolorization efficiency was examined under various current intensities, electrolysis times, and initial dye concentrations. By operating under a current intensity of 100 mA instead of 50 mA, the required electrolysis time to achieve a decolorization efficiency of 80% decreased by 40%, while the specific electrode consumption remained slightly unchanged at about 0.19 kg Al·kg−1. At a current intensity of 100 mA and an electrolysis time of 26 min, and the increase in the initial dye concentration from 10 to 50 mg·L−1 the decolorization efficiency decreased remarkably while the specific electrode consumption was kept constant at about 0.15 kg Al·kg−1 dye removed. The knowledge obtained through this study can be used for the transposition from batch to continuous mode.

Performance Evaluation of a Hybrid Enhanced Membrane Bioreactor (eMBR) System Treating Synthetic Textile Effluent

The textile industry produces a high volume of wastewater rich in toxic and harmful chemicals. Therefore, it is necessary to apply wastewater treatment methods such as membrane bioreactor (MBR) to achieve high efficiency, process stability, small footprint, and low maintenance costs. This work performed a study on a synthetic textile wastewater treatment using an enhanced membrane bioreactor (eMBR) equipped with two anoxic and one aerobic reactor and a UV disinfection unit. The results showed 100% removal of total suspended solids, 81.8% removal of chemical oxygen demand, and 96% removal of color. The SEM analysis indicated that the pores of the membrane were blocked by a compact and dense gel layer, as observed by the presence of the fouling layer. According to these results, an eMBR hybrid system is a suitable option for treating synthetic textile wastewater. Opportunities to increase the efficiencies in the removal of some pollutants, as well as stabilizing and standardizing the process are the improvements which require further investigations.

Wastewater treatment using recyclable agar-graphene oxide biocomposite hydrogel in batch and fixed-bed adsorption column: Bench experiments and modeling for the selective removal of organics

Hydrogel biocomposite using graphene oxide and agar biopolymer (agar-GO) was synthesized to treat textile wastewater through fixed-bed adsorption. After characterization, batch experiments were conducted to evaluate the pH effect in the adsorption process, adsorption isotherms, and kinetics for four cationic dyes – Nile Blue A (NB), Methylene Blue (MB), Malachite Green (MG) and Basic Fuchsin (BF). Adsorption equilibrium isotherms were fitted to Freundlich, Langmuir and Sips models, and kinetic data were adjusted to Driving Force models, and Fickian Diffusion equation. Fixed-bed experiments were carried out, and the adsorption capacities on a dry basis were 226.46 mg·g−1 (NB), 79.51 mg·g−1 (MB), 58.25 mg·g−1 (MG), 38.11 mg·g−1 (BF). LDF model was fitted with the experimental breakthrough curves. The column packed with the agar-GO hydrogel was tested for the treatment of synthetic textile wastewater. Color and total organic carbon (TOC) were evaluated and there was an indication of the adsorbent selectivity for the separation of the dyes, which can facilitate dye recovery. Agar-GO proved to be a viable and eco-friendly alternative, since a small amount of material was used to treat over 6 L of wastewater, being most of the composite biodegradable. Moreover, the material exhibited remarkable regenerative capacity, proving its effectiveness for applications in industrial textile wastewater treatment.

Controlling pathogenic risks of water treatment biotechnologies at the source by genetic editing means.

Antimicrobial-resistant pathogens in the environment and wastewater treatment systems, many of which are also important pollutant degraders and are difficult to control by traditional disinfection approaches, have become an unprecedented treat to ecological security and human health. Here, we propose the adoption of genetic editing techniques as a highly targeted, efficient and simple tool to control the risks of environmental pathogens at the source. An 'all-in-one' plasmid system was constructed in Aeromonas hydrophila to accurately identify and selectively inactivate multiple key virulence factor genes and antibiotic resistance genes via base editing, enabling significantly suppressed bacterial virulence and resistance without impairing their normal phenotype and pollutant-degradation functions. Its safe application for bioaugmented treatment of synthetic textile wastewater was also demonstrated. This genetic-editing technique may offer a promising solution to control the health risks of environmental microorganisms via targeted gene inactivation, thereby facilitating safer application of water treatment biotechnologies.

Kinetics of COD and Dye Removal for Waste Water from Textile Industry

Abstract: Water pollution poses serious threats to both the environment and the organisms that depend on their environment for survival. Due to the toxicity from dyes in textile wastewater, there is a dire need for the development of innovative and efficient treatment technologies. In this study treatability studies, using a electrochemical treatment (ECT) method followed by activated carbon (AC) based adsorption. ECT method was studied extensively for the treatment of reactive black dye. Moreover, to understand the practical applicability of ECTs, the findings were optimized for treatment of synthetic textile wastewater (STW).

The influence of sulphate on the treatment of azo dye‐containing wastewater in an anaerobic‐microaerobic compartmentalized fixed‐bed bioreactor

AbstractA fixed bed reactor (FBR) comprised of an anaerobic zone (AZ) coupled to a micro‐aerated zone (MAZ) was used for the biological treatment of synthetic textile wastewater. The azo dye in the textile effluent is expected to be reduced to aromatic amines (decolouration) in AZ followed by biological degradation of the aromatic amines due to oxygen exposure in MAZ. We focused on assessing the effect of sulphate, a common component of textile wastewaters, on the degradation of the tetra‐azo dye Direct Black 22 (DB22). The influence of sulphide, a product of sulphate biological reduction, on the removal of aromatic amines, toxic by‐products of DB22 degradation, was also analyzed. The AZ and the MAZ were filled with expanded clay balls and polyurethane foam, respectively. The chemical oxygen demand and sulphate ratio (COD/SO4−2) in the feed started at 4.8 ± 0.2 and was later changed to 0.8 ± 0.1 by increasing the sulphate content. This change consequently increased DB22 removal efficiency from 38 ± 11% to 72 ± 6% in AZ and from 56 ± 7% to 75 ± 7% at MAZ, but also resulted in high sulphide concentration and reduced redox potential (ORP) at the MAZ inlet. However, the change negatively affected the degradation of aromatic amines in the MAZ. Aromatic amines were removed only at redox potential values higher than −228 mV and biogenic sulphide concentrations lower than 44 mg HS−/L.

Treatment of high‐strength synthetic textile wastewater through anaerobic osmotic membrane bioreactor and effect of sludge characteristics on flux

AbstractThe anaerobic osmotic membrane bioreactor (AnOMBR) system was evaluated for the treatment of high‐strength synthetic textile wastewater. The chemical oxygen demand (COD) concentration was above 3,000 mg/L and color above 1,300 Pt‐Co in the synthetic textile wastewater. The study was divided into six cycles of roughly nine days each. Mono ammonium phosphate with 1 M concentration was used as draw solution. Average COD and color removal efficiencies from anaerobic bioreactor were 57% ± 5% and 43.7% ± 6%, respectively; however, in OMBR permeate, these parameters were improved to 91% ± 4% and 91% ± 2%, respectively. After each cycle, membrane cleaning was performed using osmotic backwashing for 3 hours, which produced flux recovery values between 88% and 61% from cycle 2 to cycle 6, respectively. High mixing speed of the stirrer bar (600 rpm) in the bioreactor produced a greater shear force, causing a reduction in average sludge particle size from 10 to 3.5 μm. It increased the release of soluble microbial products and extra polymeric substances to cause an initial flux decline from 3.3 to 2.2 LMH from cycle 1 to cycle 6. The study proved AnOMBR as a promising technology for high‐strength synthetic textile wastewater treatment.

Treatment of Synthetic Textile Wastewater using Enhanced Adsorption onto Calcium Alginate Polymer in the Presence of Ultrasonic Waves

Treatment of Synthetic Textile Wastewater using Enhanced Adsorption onto Calcium Alginate Polymer in the Presence of Ultrasonic Waves

Evaluation of combined anaerobic membrane bioreactor and downflow hanging sponge reactor for treatment of synthetic textile wastewater

Various toxic chemicals in textile wastewater can cause serious problems for the ecosystem and human health if it is discharged without proper treatment. In this study, the performance of textile wastewater treatment using an anaerobic membrane bioreactor (AnMBR) combined with a downflow hanging sponge (DHS) reactor is evaluated. An AnMBR with a working volume of 5 L and a third-generation DHS with a working volume of 0.5 L is used to treat synthetic textile wastewater containing Reactive Black 5 azo dye. The experiment is performed under ambient conditions using AnMBR hydraulic retention times (HRTs) of 12 and 24 h, DHS HRTs of 1.4 and 2.8 h, and membrane fluxes of 2.65 and 5.21 LMH. The AnMBR-DHS combination significantly reduces the biochemical oxygen demand, chemical oxygen demand, and color of the synthetic textile wastewater by approximately 97.3 ± 1.8%, 94.4 ± 4.8%, and 95.0 ± 1.6%, respectively. Most of the reduction occurs in the AnMBR. The HRT and membrane flux do not significantly affect the performance of the AnMBR-DHS system. The microbial community in the AnMBR is dominated by the phyla Euryarchaeota, Caldiserica, and Proteobacteria, whereas that in the DHS is dominated by Proteobacteria. Some of the genera found in the AnMBR can reportedly reduce azo dyes, whereas some of those found in the DHS can reportedly degrade sulfonated aromatic amines.

An intensified ozonation system in a tank reactor with foam block stirrer: Synthetic textile wastewater treatment and mass transfer modeling

A novel multiphase tank reactor with foam block stirrer, also called rotating foam stirrer reactor (RFSR), was used to intensify ozone mass transfer and oxidation of synthetic textile wastewater processes for the first time. Results show that the RSFR can improve the ozone mass transfer process by adjusting operation conditions and gas hydromechanics. In order to predict the volumetric mass transfer coefficient, a set of correlation was developed within ±15% deviation. Further, based on an Acid Red B (ARB) solution used as simulated synthetic textile wastewater, it was found that the removal efficiency was improved by intensifying ozone mass transfer process, and changing operation conditions can promote the transformation of the ozone oxidation path to an indirect reaction way. Finally, results show that the Fe-Co oxides coated on the foam block stirrer can further intensify the degradation processes in the ARB solution. This study gives a fundamental understanding of the intensification mechanism of the RFSR and shows the promising prospect of an RFSR used in in the wastewater treatment.

Performance evaluation of conventional membrane bioreactor and moving bed membrane bioreactor for synthetic textile wastewater treatment

In this study, conventional membrane bioreactor (MBR) and moving bed-membrane bioreactor (MB-MBR) processes were compared in synthetic textile wastewater treatment. For this purpose, the bioreactors were operated as a conventional MBR, an MB-MBR with a biocarrier filling ratio of 20 % and an MB-MBR with a biocarrier filling ratio of 10 %, respectively. In the conventional MBR operation, 93.1 % chemical oxygen demand (COD) and 87.1 % color (Reactive Red 390) removal efficiencies were obtained. In both MB-MBR operations, almost equal COD and color removal efficiencies were found as 98.5 % and 89.5 %, respectively. Moreover, offline physical and chemical membrane cleaning processes were applied every other day and every 15 days throughout the conventional MBR operation, respectively, while no physical or chemical membrane cleaning was required during both MB-MBR operations. Furthermore, lower polysaccharide concentrations of extracellular polymeric substances (EPS) and floc sizes of sludge and higher zeta potential of sludge were determined in MB-MBR. Considering the obtained results, it may be stated that the MB-MBR process is an attractive treatment technology for reducing membrane fouling propensity for treatment of textile wastewater.

Self-forming dynamic membrane bioreactor for textile industry wastewater treatment

The robustness of anaerobic dynamic membrane bioreactor (AnDMBR) for synthetic textile wastewater treatment was investigated. Textile wastewater may contain high concentrations of NaCl and sulfate, hence their impact on the AnDMBR performance was investigated in detail. A dynamic membrane was formed on a 20-μm pore sized nylon support layer at a constant flux of around 8 LMH. In the absence of sulfate addition, total and filtered (soluble) COD averaged 96 ± 49 mg/L (91% removal) and 75 ± 35 mg/L (93% removal), respectively. Sulfate addition increased total COD in the permeate to 222 ± 68 mg/L (79% removal). Average SS concentration was lower than 30 mg/L in the permeate although its concentration in the bioreactor reached 10 g/L. Throughout the AnDMBR operation dye removal averaged >97%. Sludge filterability, which was assessed by specific resistance to filtration, supernatant filtration, capillary suction time and viscosity, decreased after sulfate addition. Organic and inorganic matters in the dynamic layer were characterized by SEM-EDS and FTIR analyses.

Process optimization and filtration performance of an anaerobic dynamic membrane bioreactor treating textile wastewaters

The study aimed at investigating the performance of anaerobic dynamic MBR (AnDMBR) for the treatment of synthetic textile wastewater. A laboratory scale anaerobic bioreactor was operated to test nylon mesh support materials with different pore sizes (20 μm, 53 μm and 100 μm). The performances of the AnDMBR were evaluated with a stimulated wastewater containing 1,000 mg.L−1 COD and 100 mg.L−1 dye (Remazol Brilliant Violet 5R). To develop an effective dynamic cake layer on the support material, different operational strategies, i.e. high flux, continuous and intermittently biogas recycle were studied for process optimization and increase the filtration performances. Initially, the bioreactor was operated under continuous biogas recycle. Under this operation strategy, the cake layer was not formed, then intermittent biogas recycle was applied to improve the development of dynamic layer. Effluent SS decreased below 20 mg-SS.L−1 for all the tested different pore sized supports after the development of the cake layer. Almost complete color (>99%) and high COD removal efficiencies (95–97%) were observed. For all the three supports, the bioreactor was operated at fluxes of 5–15 L.(m2.h)−1 (LMH), which was quite high compared to conventional AnMBRs equipped with micro/ultra-filtration membranes. In order to better understand the formation and its structure, detailed cake layer characterization analyses were conducted with scanning electron microscopy (SEM), SEM coupled Energy Dispersive X-ray Spectroscopy (EDS) and inductively coupled plasma-optical emission spectrometer (ICP). Provided the formation of the cake layer, the comparable flux and removal performances with AnMBRs for all three tested support materials were possible.

Effect of salinity on removal performance in hydrolysis acidification reactors treating textile wastewater

Hydrolysis acidification (HA) is a classical method for synthetic textile wastewater treatment. However, the salinity effect on the functional mechanism of the microorganisms carrying out HA has rarely been researched. In the present study, the salinity effect on the dye removal efficiency was investigated, and the soluble microbial products (SMP), extracellular polymeric substances (EPS), and microbial community were analyzed at different salinities. The dye and COD removal rates in the HA reactor decreased with increasing salinity. Volatile fatty acids (VFAs) accumulated. The remarkable increases in SMP and EPS were found at high salinity, mainly because more polysaccharides were synthesized than protein. In addition, sequencing analysis showed that high salinity altered the microbial community structure, and Lactococcus, Raoultella and Enterococcus were the decolorizing bacteria at high salinity. This work will improve the understanding of the influence of salinity on the removal efficiency and microbial community during HA.

Performance evaluation of a novel electrolytic reactor with rotating and non rotating bipolar disc electrodes for synthetic textile wastewater treatment

Textile industry is one of the leading polluters of surface water due to the presence of various types of dyes and other hazardous pollutants. In this study, a novel rotating bipolar disc electrolytic (RBDE) reactor was designed for the treatment of textile wastewater and the performance was evaluated. The turbulence created in the system and enhanced mass transport (coagulants/ions) improved the overall performance of electrolytic cell during rotation. The effect of various parameters like current density, electrical conductivity, pH, rotation speed, and pollutant concentration on the performance of the RBDE reactor was examined in terms of COD, colour and TSS removal. Complete decolorization was obtained in 2 min and 6 min of electrolysis time in rotating and non-rotating mode of operation. COD removal was 4.8 times more in rotating electrode system (230.4 mg/L to 14.05 mg/L, 93.9% removal) compared to static mode of electrodes (230.4 mg/L to 67.9 mg/L, 70.6% removal), in 10 min of electrolysis time. Profilometry analysis confirmed that the rotation increased the electrode dissolution (8.1 μm in static and 62.3 μm in rotating electrodes) and also decreased the thickness of oxide film formation on cathode surface compared to static electrodes (0.55 μm on rotating and 6.48 μm on static electrodes). Moreover, RBDE reduced the energy consumption (1.4 kW h/kg dye) compared to static (2.1 kW h/kg) electrodes system for the complete decolourization of Rhodamine B (RB) dye.

Decolorization and phytotoxicity reduction in an innovative anaerobic/aerobic photobioreactor treating textile wastewater

The potential of a novel anaerobic/aerobic algal-bacterial photobioreactor for the treatment of synthetic textile wastewater (STWW) was here assessed. Algal-bacterial symbiosis supported total organic carbon, nitrogen and phosphorous removal efficiencies of 78 ± 2%, 47 ± 2% and 26 ± 2%, respectively, at a hydraulic retention time (HRT) of 8 days. A decrease in the HRT from 8 to 4 and 2 days resulted in a slight decrease in organic carbon and phosphate removal, but a sharp decrease in nitrogen removal. Moreover, an efficient decolorization of 99 ± 1% and 96 ± 3% for disperse orange-3 and of disperse blue-1, respectively, was recorded. The effective STWW treatment supported by the anaerobic/aerobic algal-bacterial photobioreactor was confirmed by the reduction in wastewater toxicity towards Raphanus sativus seed germination and growth. These results highlighted the potential of this innovative algal-bacterial photobioreactor configuration for the treatment of textile wastewater and water reuse.

Preparation and performance of a novel starch-based inorganic/organic composite coagulant for textile wastewater treatment

Abstract Inorganic/organic composite coagulants have received wide attention in recent years due to their outstanding properties in wastewater treatment. However, non-biodegradable synthetic polymers are largely applied as the organic components of these composites, leading to negative environmental impacts. To acquire efficient composite coagulant with less environmental risks, a novel inorganic/natural polymer composite PAFC-Starch-g-p(AM-DMDAAC) (polyaluminum ferric chloride-starch graft copolymer with acrylamide and dimethyl diallyl ammonium chloride) was prepared, and applied for textile wastewater treatment. The results showed that PAFC-Starch-g-p(AM-DMDAAC) exhibited higher and more stable dye removal efficiencies than other prepared composite coagulants. For synthetic textile wastewater treatment, PAFC-Starch-g-p(AM-DMDAAC) could reduce the chemical dosage by more than 50% compared with conventional coagulation-flocculation process. The effects of wastewater pH, conductivity and temperature on the coagulation performance were studied. High-temperature accelerated storage test proved that PAFC-Starch-g-p(AM-DMDAAC) had a strong storage stability. PAFC-Starch-g-p(AM-DMDAAC) is an eco-friendly composite coagulant with excellent performances and broad utilization range, showing promising application prospects.

Assessing textile wastewater treatment in an anoxic-aerobic photobioreactor and the potential of the treated water for irrigation

The potential of an anoxic-aerobic photobioreactor for the treatment of synthetic textile wastewater (STWW) was evaluated in terms of carbon and nutrient removal, water and toxicity reduction. The potential of the treated water for irrigation of Raphanus sativus was also assessed. Despite the low C/N ratio of the STWW, microalgae-bacteria symbiosis supported steady-state removal efficiencies of total organic carbon, total nitrogen and total phosphorus of 48±3%, 87±11% and 57±5%, respectively, at a hydraulic retention time of 10days. In addition, a consistent decolorization of the STWW was observed, with disperse orange-3 and blue-1 removals of ~80% and ~75%, respectively. This effective STWW treatment was confirmed by the reduction in genotoxicity potential and enhanced growth of R. sativus during irrigation with treated water. Finally, the heavy metal content of the soils irrigated with treated water was lower than that of STWW irrigated soils, which highlights the potential of this anoxic-aerobic photobioreactor for the treatment of textile wastewater and water reuse. However, more studies are still needed to elucidate the long-term effects of the treated water over the final consumer health.