Textile Wastewater Treatment Research Articles

Preparation characterization and photocatalytic activity of SF-ZnO nanocomposite

This article describes the fabrication of zinc oxide nanoparticles (ZnO-NPs) incorporating silk fibroin (SF) nanocomposite and its characterization. The optical, structural and morphological features of fabricated nanocomposite film were reviewed by using UV–Visible spectroscopy (UV–Vis), X-ray diffraction measurement (XRD), field emission scanning electron microscopy (FE-SEM) with energy dispersive spectroscopy (EDS) experimental techniques. The UV–Vis absorption spectrum revealed presence of zinc oxide nanoparticles in the SF film with absorption peak at λ = 362 nm. The presence of zinc oxide nanoparticles in composite film was confirmed by diffraction peaks found at scattering angle at 2θ = 35.13°, 55.32°, 62.06°, 67.10° and 68.53° respectively. The FE-SEM study showed native SF has very smooth surface morphology, whereas the SF-ZnO nanocomposite film exhibited rough surface. The ZnO-NPs present in the sample were spherical in shape. Further, the photocatalytic activity of SF-ZnO-NCs film was evaluated by observing the photo-degradation of the textile dye methylene blue (MB) under UV-B light irradiation. The maximum degradation efficiency was nearly 84 % within 340 min. The results obtained suggested that SF-ZnO-NCs film could be used as a photocatalytic material in the treatment of textile waste water.

Treatment of textile wastewater using carbon-based nanomaterials as adsorbents: a review.

Waste derived from the textile industry can contain a wide variety of pollutants of organic and inorganic natures, such as dyes (e.g., acid, basic, reactive, mordant dyes) and toxic metals (e.g., lead, chromium, cadmium). The presence of pollutants at high concentrations in textile waste makes them relevant sources of pollution in the environment. To solve this problem, various technologies have been developed for the removal of pollutants from these matrices. Thus, adsorption emerges as an efficient alternative for textile waste remediation, providing advantages as simplicity of operation, economy, possibility of using different adsorbent materials, and developing on-line systems that allow the reuse of the adsorbent during several adsorption/desorption cycles. This review will initially propose an introduction to the adsorption world, its fundamentals, and aspects related to kinetics, equilibrium, and thermodynamics. The possible mechanisms through which a pollutant can be retained on an adsorbent will be explained. The analytical techniques that offer valuable information to characterize the solid phases as well as each adsorbate/adsorbent system will be also commented. The most common synthesis techniques to obtain carbon nano-adsorbents have been also presented. In addition, the latest advances about the use of these adsorbents for the removal of pollutants from textile waste will be presented and discussed. The contributions reported in this manuscript demonstrated the use of highly efficient carbon-based nano-adsorbents for the removal of both organic and inorganic pollutants, reaching removal percentages from 65 to 100%.

Heterogeneous Fenton treatment of actual textile and dyeing wastewater by α-Cu-FeOOH nanomaterial

This work reports the successful synthesis and application of α-Cu-FeOOH in heterogeneous Fenton treatment of actual textile dyeing wastewater. The material characteristics were analyzed by SEM, EDX, BET, FTIR, and XRD methods. In heterogeneous Fenton tests, the highest TOC and color removal efficiencies were found to be 46.88 and 37.98%, respectively, in the suitable conditions of Cu/Fe molar ratio = 5%, [H2O2] = 0.1 M, [α-Cu-FeOOH] = 0.6 g/L, pH = 7, and after 60 min. The values of color and TOC after treatment well met the discharge standard for textile dyeing wastewater (QCVN 13:2015/BTNMT, Column B). The presence of copper in the material enhanced the activation of H2O2 in heterogeneous Fenton reactions under neutral environments. Therefore, α-Cu-FeOOH material has great potential for practical application in textile wastewater treatment with an initial color of 185.6 mg/L and TOC concentration of 72.54 mg/L.

Impact of salinity on anaerobic ceramic membrane bioreactor for textile wastewater treatment: Process performance, membrane fouling and machine learning models

Anaerobic membrane bioreactor (AnMBR) shows great potential for textile wastewater treatment, but high salinity in the influent may undermine its performance. This study evaluated the impact of salinity on the treatment performance of an upflow anaerobic sludge blanket (UASB) configured AnMBR using a flat sheet ceramic membrane. The salinity was stepwise increased (0, 5, 10 and 20 g/L) in four phases of the AnMBR operation. Results indicated that increased salinity jeopardized the COD removal efficiency of AnMBR from 92% to 73%, but had a marginal effect on dye removal efficacy (90–96%). Low salinity (5 g/L) boosted the biogas production whilst high salinity (>10 g/L) had a negative impact. Additionally, the increase of salinity resulted in the soluble microbial production (SMP) concentration soar and membrane fouling rate increase, peaking at a salinity of 10 g/L (Phase III) and recovering back to a lower level at a salinity of 20 g/L (Phase IV). This indicated a transition occurrence at a salinity of 10 g/L (Phase III). The microbial diversity analyses further suggested a transition from salinity-sensitive microbes (Aminiphilus, Caldatribacterium, Mesotoga, Methanobrevibacter, Methanobacterium, Methanosaeta) to salinity-tolerant microbes (Longilinea, Ignavibacterium, Rhodovarius, Bosea and Flexilinea). This transition can be associated with the increase SMP concentration and more severe membrane fouling in Phase III, which were mitigated after a new equilibrium was reached when the microbial consortium acclimatized to the high salinity. Finally, a machine learning model of the Adaboost algorithm was established to predict COD removal under different salinities. Importantly, this study revealed that AnMBR process performance and membrane operation can be maintained for high salinity textile wastewater treatment with a halophilic microbial community growth under high-salinity selection pressure.

PANI/CoO Nanocomposite Films with Excellent Photocatalytic Performance for Real Textile Wastewater Treatment

PANI/CoO Nanocomposite Films with Excellent Photocatalytic Performance for Real Textile Wastewater Treatment

Enhanced anti-fouling of forward osmosis membrane by pulsatile flow operation in textile wastewater treatment

Although osmotically driven membrane processes have exhibited great potential in a variety of applications, forward osmosis (FO) is still facing some critical challenges like membrane fouling, economics and design of draw solute. Current methods include pretreatment and membrane modification have proposed to solve fouling problem, however, these methods are still constrained by complex operational procedures and large use of chemicals. Herein, pulsatile flow, a simply-operated and chemical-free method, was employed to alleviate FO membrane fouling. Effects of pulse frequencies on membrane performance were investigated. Results showed that pulsation could effectively improve water flux and mitigate fouling. In particular, water flux of 5 Hz was 1.36 times higher than steady flow at 0 Hz, and no obvious fouling covered on membrane surface under 5 Hz. Computational Fluid Dynamics (CFD) simulation showed that the flow field on the membrane surface was evenly distributed by pulse, and cross-flow velocity changed regularly from 0.123 to 0.057 m/s in feed channel. Mechanism analysis illustrated effective transient shear stress, pulse induced membrane swing and reduced solute buildup were responsible to improve membrane flux and reduce membrane fouling. This work provides a reference for the further combination and application of pulsatile flow assisted FO to treat wastewater.

Reclamation of real textile wastewater by sequential advanced oxidation and adsorption processes using corn-cob based materials

Wastewater management has become crucial for sustaining biological life in the near future. One of the key aspects is integration of treatment processes aiming reuse of treated water for many purposes instead of water discharge. This study focused on combining two different methods, photo-Fenton-like oxidation, and adsorption, for treatment of real textile wastewater to improve water quality to be reused for irrigation. The real textile wastewater was collected from a local plant and subjected to photo-Fenton-like oxidation and adsorption as hybrid process. The operational parameters were optimized for each step by assessing the water quality according to the domestic regulations for irrigation water. The photo-Fenton-like oxidation itself was not successful to achieve the targeted water quality for reuse whereas adsorption as an additional step made the treated water reusable in terms of organic content. But the treated water still contained a certain amount of salinity due to extreme salt usage in textile processing. It was concluded that the treated water at the end of hybrid process could be used for salinity resistant plants such as sugar beet, barley, and cotton which demonstrates a promising contribution to the circular economy for biomass.

The influence of structural topology of additively manufactured PEGDA monolith on adsorption performance for textile wastewater treatment

AbstractWith the rapid advancement of three dimensional (3D) printing technology that offers flexibility to achieve desired surface area and permeability for wastewater applications, structural topology design has the potential to significantly improve the adsorption performance. This present work involves fabricating the green water technology with four different complex monolithic structural designs (Kagome, gyroid, Fischer, and body‐centered cubic [BCC]) with specific surface areas varied from 19.4 to 39.84 mm2 via digital light processing (DLP) technique. All the monolithic structures with different structural topologies were grafted with chitosan to evaluate their adsorption performance in a batch process. The influence of different structural topology on the adsorption performance and efficiency was evaluated at an optimal temperature of 60°C with optimum pH of 6.3 for a reaction time of 2 h using synthetic methyl orange (MO) dye and textile wastewater. Results indicated that the body‐centered cubic (BCC) design exhibited the highest MO adsorption capacity (12.71 mg/g), with the highest permeability (2.57 10−7 m2) and surface area (39.84 mm2). Additionally, a direct relationship was found between the surface area and the permeability of the adsorbent as well as adsorption strength. Fifty percent of color and 2.46% of chemical oxygen demand (COD) removal efficiencies were achieved to verify the adsorbent feasibility in actual application. The present work mainly establishes the feasibility of 3D printing in fabricating different monolithic structures, which enables future topology optimization for improved wastewater management.

Investigation of Textile Wastewater Treatment by Electrocoagulation Process

Bu çalışmada, Elektrokoagülasyon (EC) prosesinin temel mekanizması, prosesi etkileyen işletme parametrelerinin tekstil atıksuyundan kirletici giderimi üzerine etkileri tartışılmıştır. Tekstil endüstrisinin gelişmesiyle beraber oluşan kirleticilerin konsantrasyonları artmış ve bu durum çeşitli çevresel problemler oluşturmuştur. Tekstil atıksuları, yüksek askıda katı madde içeriği, bulanıklık, kimyasal oksijen ihtiyacı ve renk ile karakterize edilir. Oluşan atıksuların çevreye deşarjı öncesi etkili ve verimli arıtma proseslerine ihtiyaç vardır. EC, çok yönlülüğü, kurulum kolaylığı ve çevre dostu olması nedeniyle son yıllarda endüstriyel atıksuların arıtılmasında yaygın olarak kullanılmaktadır. EC prosesi için enerji gereksinimi ve oluşan çamur miktarı diğer arıtma proseslerine göre çok daha azdır. Bu gibi avantajlarından dolayı EC nin tekstil atıksularının arıtımında kullanımı yaygın olarak kabul görmektedir.

Fabrication of novel Ti/SnO2-Nb2O5 electrode in comparison with traditional doping metal oxides for electrochemical textile wastewater treatment

Textile wastewater contains a number of hazardous and refractory organic contaminants, especially various dyes such as cibacron, cycafix, monozol, and procion, that contribute to the negative effects of textile wastewater on aquatic creatures due to a limitation of light penetration and the consumption of oxygen. The selection of electrode materials is always a primary concern for electrochemical methods. SnO2-based electrodes are now being pursued by researchers due to their low cost. As a result, adding another stable oxide is recommended to enhance the efficiency and stability of SnO2-based electrodes. This study aims to fabricate the Ti/SnO2-Nb2O5 electrodes in comparison with different traditional doping metal oxides, Ti/SnO2-Sb2O5, Ti/SnO2-TiO2, and Ti/SnO2-Ta2O5, using the sol–gel method for electrochemical textile wastewater treatment. The electrode’s surface morphologies, crystal structures, and electrochemical characteristics were determined using scanning electron microscopy (SEM), X-ray diffraction (XRD), and cyclic voltammetry (CV), respectively. The SEM images illustrated that the surfaces of the four electrodes had typical cracking structures of mixed metal oxide electrodes. The presence of crystalline structures of SnO2, Sb2O5, Nb2O5, TiO2, and Ta2O5 on the electrodes was clearly determined. The direct experimental comparisons indicated that the Ti/SnO2-Nb2O5 electrode performed the best among the four oxides in the treatment of textile wastewater, with 87.0% and 84.3% efficiency in removing COD and color, respectively. A current density of 5.8 mA/cm 2 and a NaCl concentration of 2 g/L were found to be optimal operating conditions. The electrochemical properties of the fabricated electrodes showed a high oxygen evolution potential, stability, and the generation of numerous free radicals and oxidants such as •OH, H2O2, O3, and Cl2. These findings serve to inform the future selection of appropriate metal oxides to reinforce SnO2 electrodes for textile wastewater treatment.

Employing sulfolane as a green solvent in the fabrication of nanofiltration membranes with excellent dye/salt separation performances for textile wastewater treatment

This study explores the potential use of sulfolane, a green and sustainable solvent, as an alternative to toxic solvents in the fabrication of high-performance nanofiltration membranes. A comparison of Hansen solubility parameter (HSP) with N-methyl-2-pyrrolidone (NMP) indicates that sulfolane is a “poor” solvent for the sulfonated polyphenylenesulfone (sPPSU) polymer, which results in a lower critical polymer concentration (CPC) required to produce a macrovoid-free membrane structure. Moreover, the addition of a low molecular weight hyperbranched polyethyleneimine (HPEI) of MW = 800 g/mol as a crosslinker enhances the mechanical rigidity of the membranes without affecting the pore structure required for retaining salts from dye/salt mixtures, enabling practical applications in wastewater treatment. Notably, the membranes demonstrate exceptional dye/salt separation performance with a separation factor SDye/Salt of up to 69.32, even for low molecular weight dyes as low as 268 g/mol (i.e., a Disperse blue 1 and Na2SO4 mixture). To the best of our knowledge, this is the lowest MW dye ever tested for dye/salt separation. The membranes also show good antifouling capability over an extended period of use. Literature comparison shows that the sPPSU/sulfolane membrane crosslinked with HPEI800 for 60 min, referred to as sPSlf-c60, exhibits superior dye/salt separation performance, indicating their potential for the treatment of textile wastewater effluents.

Dysbiosis of gut microbiota by actual long-term exposure to textile wastewater treatment plant effluents in adult zebrafish (Danio rerio) using aquatic microcosm systems

In the future, textile industry wastewater may create greater possibilities of releasing emerging contaminants into aquatic environments. Research on textile dyeing wastewater has focused on its adverse effects on biota. However, the effects of textile wastewater on gut microbiome and host health have not yet been elucidated, especially for the toxic assessment of combined pollutants under receiving water environment conditions. During this study, adult zebrafish were exposed to realistic textile wastewater treatment plant (TWTP) effluents in aquatic microcosm systems (AMS) for six months, a histopathological examination was performed, after which 16S rRNA and metagenomic sequencing of the intestinal microbiota was conducted and fish growth performance was also examined. As a result of exposure to TWTP effluents, adult zebrafish growth was significantly inhibited, the condition factor was exacerbated, and mortality was significantly increased. Also, significant alterations were observed in zebrafish guts after chronic exposure, which are the opportunistic pathogens Flavobacterium, Aeromonas, and Escherichia. The chronic effects of increased probiotic Cetobacterium, Bacteroides, and Planctomyces deserve further attention. Metagenomic sequencing also showed that genes of core metabolism pathways were affected by TWTP effluent exposure. The study has, for the first time, demonstrated gut microbiota's susceptibility and host health of adult zebrafish to TWTP effluents using aquatic microcosm systems, which are assumed to be clean, thus warranting additional research to reveal their mode of toxicity.

Constructed "sandwich" structure to obtain recyclability and high rejection rate high-flux CA@HMSN@h-BN/PDA membrane for efficient treatment of dye wastewater

It is necessary to develop a nanofiltration membrane that can remove dye molecules efficiently and is not easily polluted for the treatment of textile industry wastewater. A novel high-flux CA@HMSN@h-BN/PDA membrane with a "sandwich" structure was obtained by assembling the support layer of the Hollow mesoporous silica nanoparticles (HMSN), and the isolation layer of the h-BN/PDA on the Cellulose acetate (CA) membrane. HMSN was synthesized using ZIF-8 as a self-sacrificial template to provide improved permeability. h-BN/PDA obtained by modifying hexagonal boron nitride (h-BN) with polydopamine (PDA) brought higher hydrophilicity, rejection rate, and stability to the membrane. The study solved the problem that the membrane separation process requires sacrificing flux and recyclability for high rejection rates. CA@HMSN@h-BN/PDA membrane has a super-hydrophilic property (water contact angle of 22.5°) and high pure water flux (4419.4 L·m−2·h−1·bar−1). Meanwhile, the CA@HMSN@h-BN/PDA membrane achieves a high rejection rate (over 99.5%) due to the special "sandwich" structure. Through cycling experiments, CA@HMSN@h-BN/PDA membranes exhibit recyclability. More importantly, CA@HMSN@h-BN/PDA membranes maintain stable performance in complex environments, such as extremely acidic/alkaline or inorganic salt interference environments. Thus the CA@HMSN@h-BN/PDA membrane has the potential for future wastewater treatment.

A tight polyethersulfone ultrafiltration membrane fabricated via polyion complex assisted phase inversion for dye desalination

In this work, a tight polyethersulfone (PES) -based ultrafiltration (UF) membrane was fabricated to separate dye and salt of textile wastewater via a novel polyion complex assisted phase inversion method in one step. Thereinto, sulfonated polysulfone (SPSF) and poly-(diallyl dimethylammonium chloride) (PDADMAC) were added into the PES dope and coagulation bath, respectively. During the phase inversion process of the precast PES/SPSF film, polycation PDADMAC could assemble with anionic SPSF and facilitate SPSF enrichment on membrane surface, forming a dense barrier layer via the electrostatic interaction between quaternary ammonium and sulfonate groups. Morphology, chemical composition, surface charges and pore size analysis characterized via SEM, FTIR, XPS, Zeta potential and Dextran filtration experiment, respectively, testified that a nonporous skin layer comprising of polyion complex and enriched SPSF was successfully constructed on the top of the PES matrix with an effective pore radius of 1.44 nm, which is smaller than that of the reference membrane prepared without using polyion complex assisted phase inversion (2.74 nm). This resultant membrane exhibited a high pure water permeance of 94 LMH/bar. When it was utilized to separate a dye/salt mixture of 100 ppm Congo red (CR) and 2 g/L Na2SO4 at 1 bar, the rejection of CR could reach 99.7%, alongside a very low Na2SO4 rejection of 8.4%, while the water permeance of dye solution maintained 61 LMH/bar. In addition, the membrane also possessed excellent stability in the pH range of 1–13 due to the strong electrostatic interaction between SPSF and PDADMAC and long-term operation stability, demonstrating its application potential in textile wastewater treatment.

Occurrences and fates of per- and polyfluoralkyl substances in textile dyeing wastewater along full-scale treatment processes

Industrial wastewater is a substantial source of per- and polyfluoroalkyl substances (PFASs) in the environment. However, very limited information is available on the occurrences and fates of PFASs along industrial wastewater treatment processes, particularly for the textile dyeing industry where PFASs occur extensively. Herein, the occurrences and fates of 27 legacy and emerging PFASs were investigated along the processes of three full-scale textile dyeing wastewater treatment plants (WWTPs) based on UHPLC−MS/MS in combination with self-developed solid extraction protocol featuring selective enrichment for ultrasensitive analysis. The total PFASs ranged at 630-4268 ng L−1 in influents, 436-755 ng L−1 in effluents, and 91.5-1182 μg kg−1 in the resultant sludge. PFAS species distribution varied among WWTPs, with one WWTP dominated by legacy perfluorocarboxylic acids while the other two dominated by emerging PFASs. Perfluorooctane sulfonate (PFOS) was trivial in the effluents from all the three WWTPs, indicating its diminished use in textile industry. Various emerging PFASs were detected at different abundances, demonstrating their use as alternatives to legacy PFASs. Most conventional processes of the WWTPs were inefficient in removing PFASs, especially for the legacy PFASs. The microbial processes could remove the emerging PFASs to different extents, whereas commonly elevated the concentrations of legacy PFASs. Over 90% of most PFASs could be removed by reverse osmosis (RO) and was enriched into the RO concentrate accordingly. The total oxidizable precursors (TOP) assay revealed that the total concentration of PFASs was increased by 2.3-4.1 times after oxidation, accompanied by formation of terminal perfluoroalkyl acids (PFAAs) and degradation of emerging alternatives to various extents. This study is believed to shed new light on the monitoring and management of PFASs in industries.

Antifouling loose nanofiltration membranes prepared via the fast codeposition of capsaicin-mimic/polydopamine for efficient dye/salt separation

Loose nanofiltration membranes (LNMs) are considered promising for dye/salt separation. However, LNM real-world applications are still hindered by membrane fouling. Here, we report the fabrication and relevant properties of novel antifouling LNMs, made by the codeposition of N,N′-((4,5,6-trihydroxy-1,3-phenylene) bis (methylene)) diacrylamide (AMTHBA) and polydopamine (PDA) onto polysulfone (PSf) via Michael addition and Schiff base processes. The introduction of the capsaicin-mimic AMTHBA, which has hydrophilic and antimicrobial properties, can markedly enhance the looseness of the selective layers, increasing the permeability and antifouling capacities of LNMs. The LNM dye/salt separation performance and surface microstructure can be adjusted by varying AMTHBA addition and codeposition time. The optimum PSf/PDA-AM 1.5 LNM achieved ultrahigh water permeance (72.21 L m−2 h−1 bar−1), excellent dye rejection (e.g., 98.69 % Congo Red) and low salt retention (e.g., 6.32 % NaCl). Notably, it also exhibited outstanding antifouling properties towards organic foulants (flux recovery ratio exceeded 98 % after 2 fouling/backwash cycles) and bacteria (sterilizing ratio of E. coli and S. aureus in aqueous solution was 87.53 % and 81.51 %). Furthermore, PSf/PDA-AM LNM maintained stable separation performance in 30 h dye/salt filtration test, and desirable retention efficiency during 12,000 ppm × h chlorination. This work provides opportunities for developing high-performance antifouling LNMs for textile wastewater treatment.

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.

Treatment of Textile Wastewater by Electrocoagulation Using Direct Solar Energy

Bu çalışmada, yenilenebilir bir enerji kaynağı güneş enerjisi ve atık metaller kullanılarak yeşil ve sürdürülebilir bir elektrokoagülasyon prosesi ile yüksek boya konsantrasyonu içeren tekstil atıksuların arıtımı değerlendirilmiştir. Doğrudan bir fotovoltaik panel (PV) ile desteklenen elektrokoagülasyon prosesinde ilk olarak güneş enerjisinden elde edilen akımın, tekstil atıksuyundaki değişimleri on saat boyunca izlenmiş ve kaydedilmiştir. Elde edilen akım değerleri 0,5A-2A aralığında değişmiş ve bu aralıkta yedi farklı akımda farklı elektroliz sürelerinde (0-60 dakika) hurdaya ayrılmış demir elektrotlar kullanılarak elektrokoagülasyon ile arıtım gerçekleştirilmiştir. Arıtım sonrasında KOİ ve renk giderim verimleri belirlenmiş ve her birim akım değeri için optimum elektroliz süresi elde edilmiştir. Ayrıca, asidik, nötr ve alkali pH koşullarında kirlilik giderimi değerlendirilmiştir. Sonuç olarak pilsiz doğrudan elektrokoagülasyonla tekstil atıksularının arıtımı atıksu pH’sında 1A 15 dk işletme koşulunda en yüksek KOİ (%92) ve renk (%95) giderimi elde edilmiştir.

Effective treatment of textile industry wastewater by combined ultraviolet assisted and Fe2+ catalyzed percarbonate oxidation

Sustainable water management is very important for industries with high water consumption and wastewater generation, such as the textile industry. This study aims to investigate the treatment of textile wastewater with ultraviolet (UV) assisted and Fe2+ catalyzed sodium percarbonate (SPC) oxidation, which is an eco-friendly treatment method in terms of both added oxidant and activation methods. Based on the removal efficiencies and reaction rates, a sorting was made as UV/SPC/Fe2+ > SPC/Fe2+ > UV/Fe2+ > UV/SPC > SPC > UV. It was observed that the removal efficiencies increased as the SPC dose increased, and decreased due to the scavenging effect with the 5 g/L oxidant dose, and the optimum SPC dose was determined as 2.5 g/L. It was determined that the removal efficiencies were higher in acidic conditions and high UV power applications. Under optimum operating conditions (pH:3, SPC dose: 2.5 g/L, Fe2+ dose: 1 g/L, UV lamps: 4), 68% COD, 80.9% UV254, and 92% color removal were achieved. Under optimum conditions energy cost, chemical cost, and operational cost were calculated as 11.9 $/m3, 0.20 $/m3, and 12.1 $/m3, respectively. By reducing the process COD concentration to 236.2 mg/L, discharge standards have been achieved, and the applicability of the UV/SPC/Fe2+ process was proven.

Molecular probing of dissolved organic matter and its transformation in a woolen textile wastewater treatment station

Woolen textile industry produces enormous wastewater (WTIW) with high pollution loads, and needs to be treated by wastewater treatment stations (WWTS) before centralized treatment. However, WTIW effluent still contains many biorefractory and toxic substances; thus, comprehensive understandings of dissolved organic matter (DOM) of WTIW and its transformation are essential. In this study, total quantity indices, size exclusion chromatography, spectral methods, and Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS) were used for comprehensively characterizing DOM and its transformation during full-scale treatments, including influent, regulation pool (RP), flotation pool (FP), up-flow anaerobic sludge bed (UA), anaerobic/oxic (AO) and effluent. DOM in influent featured a large molecular weight (5–17 kDa), toxicity (0.201 HgCl2 mg/L), and a protein content of 338 mg C/L. FP largely removed 5–17 kDa DOM with the formation of 0.45–5 kDa DOM. UA and AO removed 698 and 2042 chemicals, respectively, which were primarily saturated components (H/C > 1.5); however, both UA and AO contributed to the formation of 741 and 1378 stable chemicals, respectively. Good correlations were found among water quality indices and spectral/molecular indices. Our study reveals the molecular composition and transformation of WTIW DOM during treatments and encourages the optimization of the employed processes in WWTS.