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The high production and improper disposal of nickel converter slag (NCS) are raising serious concerns about its environmental impact, owing to the waste of resources and the foregone contribution to air, soil and groundwater pollution. This work uncovered that NCS could be reused as a superior catalyst for the treatment of textile dyeing wastewater by the heterogeneous electro-Fenton (hetero-EF) process. The NCS-laterite porous ceramsite (NLPC) catalyst showed the highest activity when the ratio of NCS to laterite was 3:2 and calcined at 900 °C. The methylene blue (MB) removal rate and chemical oxygen demand (COD) removal rate were 98.64% and 87.84%, respectively, after 30 min reaction under optimal operating parameters (100 g L−1 NLPC, 4 V of cell voltage and initial pH 3.0). Compared with the electro-Fenton (EF) system without NLPC catalyst, the degradation rate constant was increased by 223.9% (0.0452–1.464 min−1) and the energy consumption was reduced by 65.84% (2.02–0.69 kWh m−3). After six cycles, the MB removal rate only decreased by 5.35%, and the NLPC mass loss rate was 2.04%. Synergies between Co, Ni, Fe and Cu species to promote reactive oxygen species (ROS) generation were the predominant catalytic mechanism. Two possible pathways of MB degradation were deduced. In addition, the NLPC catalyst also showed excellent effects in different wastewater treatments. This work demonstrated an upgrade strategy for cleaner production of non-ferrous metallurgical by-products. [Display omitted] • NCS was reused to prepare a novel hetero-EF catalyst. • The optimal MB removal conditions (98.64% within 30 min) were 4 V and pH 3. • 1O 2 and ·OH were mainly responsible for the MB removal. • Heterogeneous reactions are dominated by synergies between Co, Ni, Fe and Cu. • NLPC could be reused six times in real water without significant deactivation. [ABSTRACT FROM AUTHOR]

The abundant discharge of dyes is harmful to aquatic ecosystem, it is meaningful to seek a resource-rich adsorbent to eliminate the pollution. Activated carbons (ACs) were prepared by low temperature phosphoric activation method using Eucommia ulmoides Oliver (EUO) wood as raw material, while magnetic activated carbons (MACs) were prepared by one-step (M1ACs) and two-step (M2ACs) hydrothermal methods combined with FeSO 4 0.7 H 2 O and FeCl 3 0.6 H 2 O for the removal of methylene blue from printing and dyeing wastewater. The specific surface area of M2ACs (1135.6 m2/g for M2AC1) prepared by two-step method was significantly higher than that of M1ACs (708.5 m2/g for M1AC1) prepared by one-step method. Impressively, the adsorptive capacity of M2AC2 stably reached the maximum value of 540 mg/g when the concentration and pH of methylene blue (MB) were 100 mg/L and 10.0, respectively. In particular, after 5 times magnetic re-adsorption experiments (79.81%), the M2ACs exhibited a strong and gratifying magnetic behavior. Therefore, the economic feasibility of the M2ACs to remove MB was relatively high than that of M1ACs. Overall, the two-step chemical activation method is a promising route to prepare high performance MACs for dyeing wastewater treatment. [Display omitted] • The activated carbons (MACs) prepared by one-step and two-step hydrothermal process. • M2ACs exhibited excellent magnetic property, adsorption capacity and recyclability. • The maximum adsorption capacity of M2AC2 for MB was 540 mg/g. • The adsorption rate of M2AC2 could reach 79.81% after 5 cycles of adsorption tests. • This study provided a convenient method for the removal of dyes from waste water. [ABSTRACT FROM AUTHOR]

Abstract: In this work, a pilot-scale (300m3/d) wastewater reclamation system was tested for printing and dyeing wastewater treatment from a textile factory. The wastewater was first hydrolyzed under anoxic condition, and then was treated under aerobic condition. Biologically treated wastewater was filtered by sub-filter technology (Patent: CN1308024A). The results showed that the average concentration of CODcr, color and turbidity in the effluent were less than 50mg/L, 10 times and 2NTU, respectively. The average CODcr, color and turbidity removal efficiencies were 91%, 92.5% and 90.9%, respectively. The treated effluent quality satisfied the requirement of water quality for printing and dyeing process. The most attracting part of the work was its extremely low color, low turbidity, low concentration of Fe and Mn, which was always demanded in textile sectors for an improved finish and better quality dyeing. [Copyright &y& Elsevier]

Abstract: A study on pretreatment of textile dyeing wastewater was carried out using an anoxic baffled reactor (ABR) at wastewater temperatures of 5–31.1°C. When hydraulic retention time (HRT) was 8h, the color of outflow of ABR was only 40 times at 5°C and it could satisfy the professional discharge standard (grade-1) of textile and dyeing industry of China (GB4287-92). The total COD removal efficiency of ABR was 34.6%, 47.5%, 50.0%, 53.3%, 54.7% and 58.1% at 5, 9.7, 14.9, 19.7, 23.5 and 31.1°C, respectively. Besides, after the wastewater being pre-treated by ABR when HRT was 6h and 8h, the BOD5/COD value rose from 0.30 of inflow to 0.46 of outflow and from 0.30 of inflow to 0.40 of outflow, respectively. Experimental results indicated that ABR was a very feasible process to decolorize and pre-treat the textile dyeing wastewater at ambient temperature. Moreover, a kinetic simulation of organic matter degradation in ABR at six different wastewater temperatures was carried through. The kinetic analysis showed the organic matter degradation was a first-order reaction. The reaction activation energy was 19.593kJmol−1 and the temperature coefficient at 5–31.1°C was 1.028. [Copyright &y& Elsevier]

The low solubility of ozone in water limits its oxidation reaction rate, while microbubbles can enhance the gas–liquid mass transfer process and effectively improve the mass transfer rate of ozone. In this study, we set up an ozone microbubble generation system, with an internal recycle, a selfmade releasing device using 3D printing and other designs to keep the system running steadily, with constant pressure, high ozone concentrations, and slow microbubble dissipation rate. This study investigated the ozone feed rate and optimization of mixing conditions through the test. With the increase of ozone feed rate, the average concentration of ozone in the solution tends to increase linearly, then decreases slightly after reaching the maximum 13.75 mg/L. On a stable running of the system, the ozone concentration of the solution could reach 13.29 mg/L. The ozone microbubble was then investigated by calculation and measurement of bubble disappearance time, particle size and mass transfer capacity. This study found the particle size of bubbles was about 42.66 μm and KLa (20) was 10.712 min–1. The system’s applications were then studied to demonstrate the effect of ozone microbubbles. Under strong alkaline conditions and without acid adjustment, COD of printing and dyeing wastewater could reach Chinese first-class A discharge standards after treatment with ozone microbubbles. Another experiment proved that ozone microbubble solution of 8 mg/L had more than 99% killing effect on Escherichia coli. [ABSTRACT FROM AUTHOR]

Widespread concerns about the impacts of exposure to chemical substances with textile dyeing activities continue to be raised. Hitherto, the percolation of synthetic colourants into the groundwater and surface water supply remains an intricate challenge abroad the nations. With the revolution of graphitic carbon nitride (g-C 3 N 4 ), there has been a gradually increasing attention in this research area. Recent advancements have been demonstrated that g-C 3 N 4 /semiconductor (CNS) nanocomposites can be envisioned as the most privileged and promising novel catalysts in the photocatalytic destruction of industrial effluents. The paper presents a review of current state of art on photocatalytic destruction of dyestuff effluents via CNS nanocomposites. Numerous techniques used to synthesize the CNS nanocomposites together with their representative examples have been reviewed. In addition, the recent research progresses on the efficacy of these nanocomposites in removing of selected dye pollutants are also summarized. This review paper ends with a summary and several future prospects on the challenges in expanding g-C 3 N 4 -based advanced nanocomposites in the possible enhancement of environmental conservation. [ABSTRACT FROM AUTHOR]

In-situ sludge reduction is an important process in the biological treatment of dyeing wastewater. In this study, an anaerobic-oxic-settling-anaerobic process (A + OSA) was employed for dyeing wastewater treatment under the condition of sludge return to investigate the efficiency of dyeing wastewater treatment and sludge reduction performance. This was compared with an anaerobic-anaerobic-oxic process (AAO) without sludge return. Results showed that treatment of dyeing wastewater with the A + OSA process gave a 30% reduction in sludge and a 90% decolourisation efficiency, which was more efficient than the AAO process. Interestingly, the effluent chemical oxygen demand from the A + OSA process was higher than that from the AAO process. This was due to the inhibition of microbial activity due to the accumulation of intermediate compounds―aromatic amines―caused by long-term sludge return. Moreover, the returned sludge may have been degraded as a co-metabolism substrate, which resulted in the concentration of extracellular polymeric substances in the A + OSA process was higher than that in the AAO process. Additionally, high-throughput sequencing analysis indicated that sludge reduction performance was correlated with the growth of Saccharibacteria. Furthermore, analysis of the enzyme activity showed that dehydrogenase and catalase content decreased in the A + OSA process. This A + OSA process could be further scaled-up and optimized to serve as a promising and effective technology for the treatment of dyeing wastewater. Image 1 • Sludge reduction and dyeing wastewater treatment were achieved in the process. • The inhibition of microbial activity was due to the accumulation of aromatic amines. • Extracellular polymeric substances content increased during sludge reduction. • Returned sludge could increase dye degradation and chroma removal. • Hydrolytic bacterium was enriched with long-term sludge recirculation. [ABSTRACT FROM AUTHOR]

This study was conducted to assess the potential of a sponges-submerged anaerobic baffled reactor (SS-ABR) for enhancing the processing performance of azo dye-contaminated wastewater. A lab-scale four–compartment SS-ABR, with a total volume of 10 L, was operated at 30 °C for 180 days. A total of 14 polyurethane sponges were added in each compartment to treat synthetic wastewater including a commercial azo dye Hellozol HSR Reactive Black. During the entire operation, in synthetic wastewater, starch was used as a sole carbon source, and the true color level was maintained at 1050 ± 98 Pt/Co. Meanwhile, the hydraulic retention time (HRT) and total COD (T-COD) in the influent were changed to evaluate the SS-ABR treatment performance. After the start-up phase, true color and T-COD removal efficiencies were recorded as 65 ± 3% and 83 ± 2%, 68 ± 5% and 81 ± 4%, and 70 ± 5% and 84 ± 2% for HRT and influent T-COD concentration of 18.6 h and 260 mg L−1, 14.6 h and 260 mg L−1, and 14.6 h and 460 mg L−1, respectively. The microbial community analysis showed that bacterial groups involved in dye degradation, such as Clostridium sp., and sulfate-reducing bacteria Desulfomonile sp. and Desulfovibrio sp. were detected prominently in the SS-ABR. Interestingly, the SS-ABR exhibited the dominance of both Geobacter sp. and Methanosarcina sp., and their occurrences in all columns were proportional to each other, revealing the formation of syntrophic relationships. • A sponges-submerged ABR (SS-ABR) was performed for enhanced decolorization. • Treatment performance of SS-ABR was stable when HRT and organic load changes. • The dominance of genus Clostridium revealed its involvement in dye decolorization. [ABSTRACT FROM AUTHOR]

Abstract: In this study, the dynamics of bacterial, fungal and archaeal populations in two-stage biological processes of a full-scale printing and dyeing wastewater treatment system were traced using cultivation and molecular biological techniques. The enumeration results indicated that bacteria were the dominant population in the system, in which the ratio of fungi to bacteria decreased in all the treatment units, while the ratio of archaea to bacteria increased significantly, especially in samples from the second-stage biological treatment process. PCR–denaturing gradient gel electrophoresis (DGGE) analysis showed that the microbial diversity increased with system running and 64.6% of bacterial, 57.6% of fungal and 38.2% of archaeal populations remained in the system from the seed sludge during system start-up. In spite of variation in the microbial community and composition of the influents, some bacterial species such as Thauera sp. and Xanthomonadaceae were present simultaneously in all the collected samples. [Copyright &y& Elsevier]

Polyamide (PA)/polydopamine (PDA)/poly(vinylidene fluoride) (PVDF) nanocomposite membranes were prepared by the method of dopamine (DA)/polyethyleneimine (PEI) co-deposition integrating with interfacial polymerization (IP) with trimesoyl chloride. Fourier transform infrared spectrometer, scanning electron microscopy, atomic force microscopy and water contact angle were used to characterize the PA/PDA/PVDF nanocomposite membranes. Effects of the co-deposition time, the mass ratio of DA to PEI, the molecular weight of PEI and the content of DA + PEI on the morphologies and roughness of the membrane surface, the cross-section of the selective layer and the performance of the PA/PDA/PVDF nanocomposite membranes were investigated. Results showed that the co-deposition time has significant effect on the rejection of PA/PDA/PVDF nanocomposite membranes, the other three factors have few effects on the rejection. All the four factors have remarkable effects on the permeation of the PA/PDA/PVDF nanocomposite membranes. When the rejection of PEG1000 and RB5 was 99%, the permeation of water and reactive black five (RB5) dyeing wastewater was 16.67 and 8.2 L m–2 h–1 bar–1, respectively. The water flux and the RB5 dyeing wastewater permeation of the PA/PDA/PVDF nanocomposite membranes were 31.14 and 15.03 L m–2 h–1 bar–1, respectively, when the PEG1000 and RB5 rejections were above 90%. Results above showed that the PA/PDA/PVDF nanocomposite membranes developed in this paper possess the potential application value in the dyeing wastewater treatment and reclamation. [ABSTRACT FROM AUTHOR]

The advanced treatment of printing and dyeing wastewater by adsorption using activated coke was studied. Specifically, the effects of adsorption conditions on wastewater treatment were examined by adsorption experiments. Meanwhile, the adsorption behaviors of organic pollutants by activated coke were investigated by the adsorption kinetics and isotherms. The chemical oxygen demand (COD) removal met the printing and dyeing wastewater discharge requirement under the conditions of initial COD concentration 158 mg/L, adsorption time 360 min, activated coke concentration 30 g/L and adsorption temperature 308 K. After adsorption, 53.86% of COD was removed. The adsorption kinetics of COD by activated coke followed the pseudo-second-order model and the adsorption isotherms could be expressed by the Freundlich model. Moreover, thermal regeneration of spent activated coke was studied. Specifically, the effects of regeneration conditions on the thermal regeneration efficiency of spent activated coke were examined by thermal regeneration experiments. Meanwhile, the reusability of activated coke for organic pollutants removal was evaluated by the successive adsorption-regeneration cycles. 98.13% of thermal regeneration efficiency could be achieved under the conditions of regeneration temperature 1,073 K, regeneration time 30 min and CO2 flow rate 150 mL/min, and activated coke still maintained 92.54% of regeneration efficiency after ten adsorption-regeneration cycles. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A new catalyst- CZPLz, was used to treat real dyeing wastewater for the first time. • The CZPLz catalyst can be used many times. • Four elements including two rare earth elements were introduced into the catalyst. • The different catalysts were studied from the lattice structure. • The using of the zeolite fludized bed reactor. Abstract CuO-ZnO-Pr 2 O 3 -La 2 O 3 -zeolite (CZPLz) were employed for electro-Fenton (CZPLz-electro-Fenton) degradation of real dyeing wastewater in an electrochemical reactor with an steel electrode cathode and a titanium ruthenium iridium electrode anode. A variety of metal oxide catalyst particles were synthesized by an impregnation method with zeolite as the carrier under the following conditions: different load materials, different doping ratios, different calcination temperatures, and different calcination times. The obtained heterogeneous catalysts were used to treat real dyeing wastewater using the electro-Fenton process in a fluidized bed and were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrode-gradation of real dyeing wastewater was performed at 30 V for 60 min. The dyeing wastewaters were analyzed by UV–vis spectrophotometry and the potassium dichromate method. The maximum decolorization ratio was 91.21%, and the maximum COD removal efficiency was 61.1%, and these values were obtained for a composite metal electrode catalyst for which the CuO, ZnO, Pr 2 O 3 and La 2 O 3 amounts were present at a ratio of 50:25:2:20 at 600℃ for 3 h. After 5 cycles of using the composite metal electrode catalyst, the decolorization ratio of the real dyeing wastewater was 86.67%. Therefore, it can be concluded that the catalyst under the optimum process parameters can be used many times. Additionally, it was confirmed that Cu2+/Zn2+/Pr3+/La3+ cations were successfully substituted in the zeolite, giving rise to the changes in the catalytic activity of the catalyst observed by XRD and SEM analyses of the composite metal electrode catalyst. Hence, the results of this experiment could establish a theoretical foundation for industrial applications. [ABSTRACT FROM AUTHOR]

Abstract: A study of the treatment of printing and dyeing wastewater was carried out using the combined process of anoxic baffled reactor-biological contact oxidation. The results showed the pH ascended continuously and the oxidation-reduction potential dropped gradually from compartment 1–6 in ABR. When hydraulic retention time was 12h, color removal efficiency was 92% and the color of effluent of ABR could satisfy the professional emission standard (grade-1) of textile and dyeing industry of China. The total COD removal efficiency of the combined process was 86.6% and the COD of effluent could satisfy the professional emission standard (grade-2) of textile and dyeing industry of China. [Copyright &y& Elsevier]

Abstract: For pretreatment of the feed water of membrane processes, chemical coagulants such as HOC-100A, alum, and ferric chloride were used. The feed water used in this experiment was a synthetic dyeing wastewater composed of Direct Red 75, polyvinyl alcohol (PVA), NaCl and Na2SO4. Total concentration of the materials in the feed water was 2500ppm. The following optimum coagulation pretreatment conditions were sought using jar tests: for HOC-100A, the concentration of HOC-100A was 2000ppm at the coagulation pH 7, for aluminum sulfate, 4000ppm at pH 7, and for ferric chloride, 1500ppm at pH 10. Under optimum conditions for all the coagulants used, about 90% of materials was removed from the solution when checked with the UV absorbance of the solution before and after treatment. [Copyright &y& Elsevier]

[Display omitted] • Surface sorption and interstitial sorption are the mechanism for dye removal by PBC. • There are various factors affecting dye adsorption by PBC. • Optimum parameters need to be obtained for the maximum removal of dyes by PBC. • The best dosage of PBC or modified PBC is generally 0.1–10 g/L. • There are many contents worthy of in-depth study for the treatment of dyes by PBC. Printing and dyeing wastewater (PDW) has characteristics of large amount of water, elevated content of residual dyes, poor biodegradability, high alkalinity and large change of water quality, making its treatment difficult. Development of efficient and economic PDW treatment technology has gained considerable interest in the field of environmental protection. Use of plant biomass carbon (PBC) for the adsorption of dyes is a feasible and economical technology. This review summarizes current literature discussing the preparation method and physicochemical characteristics of PBC prepared from different plant species, the effect of PBC on the removal of dyes, influencing factors affecting the removal, and relevant adsorption models. The shortcomings of current research and the direction of future research are also pointed out in the review. [ABSTRACT FROM AUTHOR]

Novel magnetically recyclable spinel nickel ferrite/multi-walled carbon nanotubes hybrids (NiFe 2 O 4 /MWCNTs hybrids) with different MWCNTs content were prepared by a facile one-step hydrothermal method. The as-prepared NiFe 2 O 4 /MWCNTs hybrids were characterized by powder X-ray diffraction (XRD), UV–vis diffuse reflectance spectra (DRS), scanning electron microscope (SEM) and vibrating sample magnetometer (VSM). Photocatalytic activity of NiFe 2 O 4 /MWCNTs hybrids was investigated by photocatalytic decolorization of Congo Red (CR) in aqueous solution under simulated solar light irradiation. NiFe 2 O 4 /MWCNTs yielded efficient decolorization of CR solution with an apparent rate constant of 0.01433 min −1 , which was 2.18 times that of NiFe 2 O 4 . Significantly enhanced activity of NiFe 2 O 4 /MWCNTs hybrids resulted from the synergistic contribution of both high adsorption capacity towards CR and the participation of holes ( h + ), •OH radicals and O 2 •− radicals. In addition, the NiFe 2 O 4 /MWCNTs hybrids can be recovered conveniently using an external magnet. As a result, the novel NiFe 2 O 4 /MWCNTs could gain a promising application in treatment of various dyestuff wastewaters on a large scale. [ABSTRACT FROM AUTHOR]

Herein, physicochemical features of poly(acrylic acid- co -acrylamide) hydrogels were studied via swelling, SEM, TGA, DTA and thermoporometric measurements as well Monte-Carlo simulations. Physicochemical characteristics of metal–embedded hydrogel nanocomposites were investigated by ICP-OES, XRD, SEM/EDX and HRTEM analysis. Catalytic behaviour of nanocomposites was examined through multi-repetitive oxidative degradation of methylene blue (MB) from wastewater. Decay of MB concentrations was followed up kinetically by UV–vis spectrophotometer and TOC analyzer. Poly(acrylic acid- co -acrylamide) hydrogels are promising candidates for embedding diverse-shaped nano-sized metallic species (Co, Cu, Ni and Fe) with advanced protectiveness behaviour against deactivation during degradation processes. Surface-sited nanometals developed pseudo-first ordered degradation profiles with inferior reusability trends. Bulk-sited nanometals exhibited strong tendency towards MB mineralization, obeying pseudo-second ordered progression. Hydrogel embedding nickel nanocomposite served as typical “Auto-active” catalyst regarding to its ability to gather reactants and radicals beneath nanometallic particles deep inside monolithics, thereby preserving the reduced metallic form throughout the degradation processes. [ABSTRACT FROM AUTHOR]

A simple process for the preparation of mesoporous silica microsphere (MSM) as adsorbent was synthesized via sol–gel method between tetraethyl orthosilicate and polyethylene oxide-polypropylene oxide-polyethylene oxide (F127). The influencing factors of MSM on methyl orange simulated dyeing wastewater were investigated in detail. Five adsorption isotherm models, kinetics, thermodynamics, and mechanism were studied. Under the optimum conditions, the adsorption rate was up to 86.44% (only at 21 min). The adsorption process of methyl orange by MSM was indicated as a non-spontaneous monolayer chemical adsorption process, which obeyed the pseudo-secondorder kinetic model. The above showed that the MSM as-prepared in this paper was a simple, efficient and promising adsorbent for wastewater treatment, which provided a theoretical basis and technical support for the dyeing wastewater treatment. [ABSTRACT FROM AUTHOR]

New two-dimensional (2D) material MXene based lamellar membranes constructed from 2D MXene nanosheets have shown promising potential for water treatment with excellent selective property and high water flux. However, the effect of lateral size of MXene nanosheets on the membrane property and performance was rarely considered. Herein, the MXene nanosheets with different lateral size (552.3 nm, 397.5 nm and 281.8 nm) segregated via adjusting centrifugation conditions were used to prepare MXene membranes. XRD and cross-sectional SEM images confirmed that the resulting MXene membranes had the similar d-spacing and thickness. The MXene membrane with the smallest lateral size, MXene (S) -M, owned the largest surface roughness with reduced surface hydrophilicity. Lateral size determined mass transfer pathway and transfer resistance, which consequently influenced the water permeance and rejection of MXene membranes for dyeing wastewater treatment. MXene (S) -M with the shortest mass transfer pathway had the high water permeance while the MXene membrane with larger lateral size (MXene (L) -M and MXene (M) -M), possessing longer mass transport pathway, promoted high dye rejection. [Display omitted] • Lateral size played key roles in characteristic and performance of MXene lamellar membranes. • Smaller lateral size resulted in larger surface roughness but slightly reduced hydrophilicity. • Lateral size influenced the length of mass transfer pathway. • Lateral size significantly affected water permeability and rejection of MXene membranes. • MXene membrane with medium lateral size had good water permeability and rejection. [ABSTRACT FROM AUTHOR]

Abstract: The treatment of the wastewater taken from a wool dyeing processing in a wool manufacturing plant was investigated using an anaerobic/aerobic sequential system. The process units consisted of an anaerobic UASB reactor and an aerobic CSTR reactor. Glucose, alkalinity and azo dyes were added to the raw acid dyeing wastewater in order to simulate the dye industry wastewater since the raw wastewater contained low levels of carbon, NaHCO3 and color through anaerobic/aerobic sequential treatment. The UASB reactor gave COD and color removals of 51–84% and 81–96%, respectively, at a HRT of 17h. The COD and color removal efficiencies of the UASB/CSTR sequential reactor system were 97–83% and 87–80%, respectively, at a hydraulic retention time (HRTs) of 3.3 days. The aromatic amines (TAA) formed in the anaerobic stage were effectively removed in the aerobic stage. [Copyright &y& Elsevier]

After the advanced treatment of textile and dyeing wastewater, the concentration of total nitrogen (mainly nitrate) was still high while it lacked a biodegradable organic carbon source for further biological denitrification. Biological denitrification reactor with iron-based materials (both Fe and Fe/Cu) resulted in higher nitrogen removal efficiency (30% and 20%) compared to control (12%). However, the microbial mechanism was unknown. 16S rRNA genes sequencing and metagenomic sequencing were used to analyze the microbial community structure and functional genes in the process of iron-based materials enhanced biological denitrification of textile and dyeing wastewater. Microbial communities obtained from the two sequencing methods were quite different. The results of 16s rRNA genes sequencing indicated that both Fe and Fe/Cu influenced the microbial communities. Fe/Cu had a more profound effect on the microbial community and the diversity of the microbial community in the Fe/Cu reactor was relatively low. Metagenomic analysis showed that Proteobacteria was dominant in all samples (47%-80%). The biofilm formed on the surface of Fe and Fe/Cu enriched more functional microorganisms, which promoted denitrification of nitrate. The abundance of genes relating to nitrogen metabolism was higher in the samples on the surface of Fe and Fe/Cu, and therefore they had a stronger ability of nitrogen metabolism. [ABSTRACT FROM AUTHOR]

Zirconium oxide nanoparticles supported activated carbon (ZrSAC) was successfully synthesized using a simple microwave irradiation method. The derived UV light sensitive ZrSAC composites were characterized using powder X-ray diffraction (XRD), Fourier transform infra-red spectroscopy (FTIR), high resolution scanning electron microscope (HRSEM) with energy dispersive X-ray analysis (EDX), X-ray photoelectron spectroscopy (XPS), and Brunauer Emmett Teller (BET) surface area analyzer. Optical properties of ZrSAC composites were studied using UV–vis diffuse reflectance spectroscopy and photoluminescence spectroscopy (PL), which exposed prolonged light absorption in UV light region and hold better charge separation capability, respectively as compared to pure ZrO 2 . The photocatalytic activity was tested by the degradation of textile dye waste water (TDW) under UV light irradiation. Chemical oxygen demand (COD) of TDW was measured before and after the photocatalysis experiment under UV light to evaluate the mineralization of wastewater. The results demonstrated that ZrSAC composites showed a splendid photocatalytic enrichment over pure ZrO 2 . The coordinated blending of the oxygen vacant sites, structural defects of ZrO 2 along with electron transmission capacity and presence of surface oxygen on AC has led to the lasting light absorption, delayed charge recombination, and sustenance, which favor the enrichment of the photocatalytic activity of ZrSAC. [ABSTRACT FROM AUTHOR]

In this study, advanced oxidation processes were applied to the treatment of a textile dyeing wastewater. The effluent presents a dark blue color, with a maximum absorbance peak at 594 nm, alkaline pH (pH = 12.4), high organic contents (COD = 1,400 mg L–1). Experiments were conducted on a lab-scale prototype using UV lamp as light source and pillared natural clay with Fe and Al as catalyst. All the processes examined lead to an effective decolorization and mineralization, but the most efficient process was the photo-Fenton, contributing to 93% decolorization and 88.8% mineralization after 3 h of reaction under UV irradiation. Characteristics of wastewater after treatment were COD below 250 mg L–1, pH 8.5 and uncolored. Thus the resultant water has conditions that are suitable for releasing in public sewage systems. [ABSTRACT FROM AUTHOR]

Improved anaerobic baffled reactor-anoxic/oxic (ABR-A/O) coupling process was used for printing and dyeing wastewater treatment in our full-scale study, which was able to reach the effluent standard stably, especial for the characteristic pollutants and aromatics removal. According to our results of microbial community analysis by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE), the divisions of ABR enabled the functional microorganisms to distribute in different compartments and contributed to each compartment of performing its own functions with more efficiency. The first, second, and third compartments are major in macromolecular organics hydrolysis and sulfate reduction, while the main responsibilities of the fourth, fifth, and sixth compartments are aromatic compounds degradation and denitrification. Many kinds of aromatic anaerobic degradation microorganisms were found in our ABR, such as Pseudomonas stutzeri, Dechloromonas aromatic, Pseudomonas putida, and Aromatoleum aromaticum. Initially, abundances of bcrA genes climbed up and then dropped along with the sequential six compartments of ABR and it indicated that the highest aromatics degradation efficiency were obtained at the fifth compartment, rather than other compartments, which was probably caused by its moderate substrate concentration and biodegradability. [ABSTRACT FROM AUTHOR]

The processing of gemstones, mainly the dyeing step, generates a high volume of wastewater containing a high concentration of Rhodamine B. This wastewater is potentially toxic and contains non-biodegradable substances. For this reason, it is necessary to develop methodologies to treat this type of wastewater. Therefore, in this work, a sequential process of electro-Fenton conjugated with adsorption were developed to treat this type of wastewater. The gemstones dyeing wastewater presented between 735.5 and 1,943.0 mg L–1 of Rhodamine B. Firstly, the electro-Fenton process was applied, and removal superior to 65% of the RhB concentration were observed. Subsequently, adsorption was applied using a strong cationic resin at a pH of 2.0. In this condition, the adsorption capacity predicted by the Langmuir model was 247.3 mg g–1. The breakthrough curves were inclined with a suitable mass transfer zone. The sequential process of electro-Fenton and fixed-bed adsorption were able to remove 100% of the RhB from the gemstones’ wastewater, being an effective alternative to treat this type of effluent. [ABSTRACT FROM AUTHOR]

Wastewater in Shaoxing wastewater treatment plant (SWWTP) is composed of more than 90% dyeing and printing wastewater with high pH and sulfate. Through a combination process of anaerobic acidogenic [hydraulic retention time (HRT) of 15h], aerobic (HRT of 20h) and flocculation–precipitation, the total COD removal efficiency was up to 91%. But COD removal efficiency in anaerobic acidogenic unit was only 4%. As a comparison, the COD removal efficiency was up to 35% in the pilot-scale upflow anaerobic sludge bed (UASB) reactor (HRT of 15h). GC–MS analysis showed that the response abundance of these wastewater samples decreased with their removal of COD. A main component of the raw influent was long-chain n-alkanes. The final effluent of SWWTP had only four types of alkanes. After anaerobic unit at SWWTP, the mass percentage of total alkanes to total organic compounds was slightly decreased while its categories increased. But in the UASB, alkanes categories could be removed by 75%. Caffeine as a chemical marker could be detected only in the effluent of the aerobic process. Quantitative analysis was given. These results demonstrated that GC–MS analysis could provide an insight to the measurement of organic compounds removal. [Copyright &y& Elsevier]

Abstract: In the present study, electrochemical degradation experiments were conducted to degrade a textile dye namely Reactive Blue 19 (RB-19). A laboratory scale bench-top reactor was used to investigate the effect of various operating parameters using titanium based dimensionally stable anode (DSA). The oxidation of RB-19 takes place in the bulk solution with electrolytically generated chlorine/hypochlorite. Increasing the initial pH and increasing the reaction temperature decreases the de-colorization efficiency. At the same time, increasing the chloride concentration and increasing the current density showed an increase in the color removal. The complete removal of color was achieved within a short period of electrolysis for different concentrations of RB-19. However, the removal of chemical oxygen demand (COD) and total organic carbon (TOC) was 55.8% and 15.6%, respectively, for 400mg/L RB-19 with 1.5g/L sodium chloride concentration. The intermediate compounds formed during the degradation were identified using a gas chromatography coupled with mass spectrometry (GC/MS). In the present study, no chlorinated organic compounds were detected during the course of electrolysis. The major compounds identified were benzene, 2-hydroxy, 4,4-napthaquinoine (C.I. Natural orange 6), 1-aminoanthraquinone (C.I. Diazo fast red AL), benzyl alcohol, benzaldehyde, benzoic acid, phthalic anhydride, phthalide, phthaldehyde and 1,3-indanone. [Copyright &y& Elsevier]

Abstract: Using a pilot scale continuous system with activated sludge, the effect of the variability of non-pretreated synthetic textile wastewater containing reactive dyes on the pollution bio-removal and on the characteristics of activated sludge (sludge volume index, floc size and shape, filamentous bacteria abundance) has been monitored. Off-line batch respirometry tests have been used in parallel to assess the toxic effects of some of the reactive dyes. Experiments were run by increasing the concentration of a single dye (Run 1) and by feeding with a non-repetitive (Run 2) or a repetitive (Run 3) sequence of dyes. In all runs dyes were added to a synthetic wastewater of constant composition. Although the biomass was significantly upset by some of the dyes, it was able to cope up with the variations of their chemistry and remained active throughout the experiments and could contribute to COD removal. The dyes were partially adsorbed but not degraded by the micro-organisms. [Copyright &y& Elsevier]

Membrane biofouling is an unevadable problem that occurr during the reverse osmosis (RO) desalination of dyeing wastewater; therefore, it is necessary to minutely understand biofouling characteristics of RO membranes to effectively hinder the fouling. In this study, two sets of laboratory-scale desalination systems of biologically treated dyeing wastewater were operated, respectively, for 10 and 30 d, and the performance and biofouling of RO membrane were investigated. The obvious decrease of permeate flux after 10 d of operation reflected a more serious membrane fouling. The analysis on surface morphology, foulant characteristics, and active biomass of membrane fouling layer exemplified that biofouling was perhaps responsible for the permeate flux decline, and the fouling was more serious after operation of 30 d than that of 10 d. Further, bacterial community of biofilm showed that Proteobacteria was the most predominant, followed by Firmicutes and Bacteroidete. The relative abundance of γ-Proteobacteria significantly decreased and that of α-Proteobacteria, Clostridia, and Sphingobacteria increased with operation time, which seemed to facilitate the more developed/mature biofilm formation. The results would provide fundamental information for effective strategy on prevention and control of membrane biofouling during RO desalination of dyeing wastewater. [ABSTRACT FROM AUTHOR]

Metallic glasses (MGs) are promising candidates for catalysts with high efficiency for dyeing wastewater remediation, due to their metastable nature, disordered structure, and large residual stresses. However, dyeing wastewater usually contains a high concentration of inorganic ions which may have adverse effects on the degradation process, while the impacts of these ions on MGs' degradation capability have often been overlooked and still remain unknown. Thus, the roles of inorganic ions (Cl - , NO 3 - , SO 4 2 - , and H 2 PO 4 -) on the degradation of azo dye by Fe-based MG with nominal composition of Fe 81 Si 4 B 14 Cu 1 were systematically investigated. The results showed that the inorganic ions have significant influence on MG's surface morphology, degradation capability, mineralization and durability. All these aspects need to be considered prior to application of MGs for azo dyes degradation in real natural contaminated water or saline wastewater. • Inorganic ions significantly change the degradation path way of azo dyes by Fe-based MG. • Cl - , NO 3 - , SO 4 2 - and H 2 PO 4 - deteriorate the durability of Fe-based MG. • Cl - , SO 4 2 - and H 2 PO 4 - impede the Fe-MG to remove the TOC in dyeing wastewater. • This work provides reference for the application of Fe-based MG in wastewater treatment. [ABSTRACT FROM AUTHOR]

In this study, fluorescent dissolved organic matter (FDOM) in real printing and dyeing wastewater (PDW) during full-scale two-stage treatment was characterized using excitation-emission matrix (EEM), apparent molecular weight (AMW) cutoff by centrifugal ultrafiltration and high-performance liquid chromatography with fluorescence detector (HPLC-FLD). EEMs of PDW during treatment were relatively invariable with two typical and dominant peaks (P1, 275/320 nm and P2, 230/340 nm). The removal rates of P1 intensity and P2 intensity were both lower than those of DOC or UVA 254 during the 1st stage and 2nd stage treatment. The <3 kDa fraction made major contribution to DOC, UVA 254 , P1 and P2 intensity. The DOM fractions with different AMW exhibited different removal behaviors during the 1st stage and 2nd stage treatment. The <3 kDa fraction of FDOM was poorly removed by biological treatment alone. The HPLC-FLD multi-emission scan results indicated that the major part of FDOM clusters were hydrophilic and they were more difficult to remove than the transphilic and hydrophobic FDOM clusters. According to the physicochemical properties of FDOM in PDW, selective adsorption and advanced oxidation process could be prior options for PDW advanced treatment. Image 1 • FDOM in PDW was more refractory than nonfluorescent DOM during treatment. • The <3 kDa fraction predominately contributed to DOC, UVA254 and fluorescence. • Hydrophilic FDOM in PDW was harder to remove than transphilic and hydrophobic FDOM. [ABSTRACT FROM AUTHOR]

Azo dye is the most versatile class of dyes used in the textile industry. Although the sulfidogenic process shows superiority in the removal of azo dye, the role of biogenic sulfide produced by sulfate-reducing bacteria (SRB) in the decolorization of azo dye is unclear. This study explored the mechanism of biogenic sulfide for removal of a model azo dye (Direct Red 81 (DR 81)) through biotic and abiotic batch tests with analysis of intermediates of the azo dye degradation. The results showed that biogenic sulfide produced from sulfate reduction directly cleaved two groups of azo bond (-N N-), thereby achieving decolorization. Moreover, the decolorization rate was enhanced by nearly 3-fold (up to 42 ± 1 mg/L-hr; removal efficiency > 99%) by adding an external carbon source or elevating the initial azo dye concentration. This study showed that biogenic sulfide plays an essential role in azo dye decolorization and provides a new avenue for the potential application of biogenic sulfide from the sulfidogenic system for the treatment of azo dye-laden wastewater. [Display omitted] • Azo dye could be effectively removed under sulfidogenic condition. • Biogenic sulfide plays a key role in decolorization of azo dye. • Biogenic sulfide donated electrons to the –N N- in azo dye achieving decolorization. • Addition of pyruvate or riboflavin boosted decolorization of azo dye. • Sulfidogenic process could be an alternative for textile wastewater treatment. [ABSTRACT FROM AUTHOR]

Chitosan-based flocculants are efficient and biodegradable, possessing the potential application in water treatment. A chitosan-based flocculant, CTS-g-PAM, was prepared via grafting copolymerization. Two main structures of CTS-g-PAM were detected by X-ray photoelectron spectroscopy (XPS), and they related to the different performances of CTS-g-PAM in the treatment of model azo dyeing wastewater in terms of removal efficiency, floc size and zeta potential. CTS-g-PAM with the optimal ratio of C N to –NH– owned the best performance. C N reinforced the interaction between CTS-g-PAM and azo dyes and charge neutralization while the flocs formed in the case were large and compacted. However, excessive C N accelerated itself hydrolysis and leaded to the decomposition of CTS-g-PAM, deteriorating the performance of the flocculant. Image 1 • Two different structures of CTS-g-PAM were discovered via XPS. • The ratio of two structures was different in various synthesis conditions. • The moderate C N in CTS-g-PAM contributed to its better performance in the treatment. • C N reinforced the interaction between CTS-g-PAM and azo dyes. • Excessive C N accelerated itself hydrolysis and decomposition of CTS-g-PAM. [ABSTRACT FROM AUTHOR]

The textile dyeing is a significant worldwide economic pillar of the industry mainstay of the region's industrial economy. Therefore, significant attention should be paid to its emitted volatile organic compounds (VOCs) regarding their potential adverse effects on ecosystems and human health. In this study, a spray tower (ST) (preferential elimination of hydrosoluble VOCs) and biofilter (primary removal of particle-free VOCs) were used in combination. Three techniques, including gas chromatography-mass spectrometer (GC-MS), e-nose, and Proton transfer reaction time-of-flight mass spectrometry (PTR-TOF-MS) were used to accurately identify the associated VOCs profile. In total, 50 types of VOCs, with total concentrations ranging from 1.26 to 2.79 mg m−3, were detected from the outlet of the TDWTP over a 90-day treatment period. The highest level occurred for nitrogen- and oxygen-containing compounds (NAOCCs), followed by aliphatic hydrocarbons (AIHs), aromatic hydrocarbons (AHs), and halogenated hydrocarbons (HHs). Average removal efficiencies (REs) of the four studied VOC groups (NAOCCs, AIHs, AHs, and HHs) were 66.7%, 67.9%, 11.7%, and 52.1%, respectively. Proteobacteria dominated the biofilter, followed by Actinobacteria, Firmicutes, and Bacteroidetes. A positive correlation was observed between the relative abundance of Proteobacteria and the RE of NAOCCs, with RE significantly increased from 38.1% (day 1) to 83.2% (day 90). The degradation of these organic pollutants, such as NAOCCs, may be mainly performed by the dominant genus, such as Acidithiobacillus and Metallibacterium, as predicted by PICRUSt. A respiratory health risk evaluation demonstrated that the cancer and non-cancer risks of typical VOCs were dramatically reduced after the above-mentioned purification. The combined results indicate that the ST-biofilter is an efficient approach for the end-of-pipe treatment of exhausted gas in TDWTP and helps attenuate human health risk. Image 1 • Pilot-scale end-of-pipe removal of VOCs from textile dyeing wastewater treating plant. • ST-BF reactor show high and stable removal ability to odorous VOCs. • Bacteria increased in relative abundance contributed highly to VOCs removal. • Strong correlation among Proteobacteria and REs of NAOCCs was observed. • Health risks of target VOCs decrease significantly after the treatment. [ABSTRACT FROM AUTHOR]

The present study investigates the electrochemical oxidation (EO) of real leather dyeing wastewater coming from a local modern tannery in Fez (Morocco). Experiments were performed in an electrochemical reactor using Ti/Pt anode. Response surface methodology and full factorial central composite design were used to investigate the combined effect of three independent operating parameters considered for the optimization of the EO process: electrolysis time (t), current density (j) and temperature (T). Chemical oxygen demand (COD) removal (Y1) and specific energy consumption (SEC) in kWh/kg of COD removed (Y2) were used as responses to examine the degradation of wastewater. The obtained quadratic model was statistically tested using analysis of variance. The correlation coefficients for the model (R2) were 0.9986 and 0.9830 for COD removal and SEC, respectively. The best conditions for maximum COD removal and minimum specific energy consumption in the present study were t = 2.11 h, j = 18.70 mA/cm2 and T = 286.18 K. Under these optimum conditions, 81.2% of COD removal was observed with energy consumption of 93.85 kWh/kg of COD removal. Fourier transformed infrared spectroscopy analysis was used for the characterization of effluent. Evolution of inorganic ions concentration and changes of turbidity, pH and conductivity of wastewater during the EO process were also followed. [ABSTRACT FROM AUTHOR]

combined process consisting of Moving-Bed Biofilm Reactors (MBBRs) with Polyurethane-Dyeing Sludge Carbonaceous Material (PU-DSCM) foam and chemical coagulation was investigated for dyeing wastewater treatment. The pilot-scale MBBR system was composed of two aerobic MBBRs in series. Each reactor was filled with 20% (v/v) of Polyurethane-Dye Sludge Carbonaceous Material foam (PU-DSCM foam) inoculated with a white-rot fungus, Phanerochaete chrysosporium, for biological treatment followed by chemical coagulation with FeCl or alum. In the MBBR process, 79% of COD and 54% of color (influent COD = 539 mg/L and color = 622 PtCo units) were removed at MLSS concentration of 2900 mg/L attached to the PU-DSCM carrier and 48 hr of short Hydraulic Retention Time (HRT) at steady state. The biologically treated dyeing wastewater was subjected to chemical coagulation. After coagulation with alum at the optimum dosage (1.55 mg alum/mg COD), 95.7% of COD and 73.4% of color were removed in overall. The combined process of fungal MBBRs and chemical coagulation has promising potential for dyeing wastewater treatment. [ABSTRACT FROM AUTHOR]

The reckless discharge of untreated industrial wastewater into the environment has caused serious pollution. Sunlight driven degradation with assistance of catalysts is a promising strategy for removing contaminants from water. TiO 2 nanoparticles have been successfully immobilized on melamine foam via a biomimetic polydopamine coating strategy followed by a carbonization treatment. The obtained carbonized TiO 2 nanoparticles-coated melamine foam inherited the porous structure from pristine melamine foam and had a high loading density of TiO 2 nanoparticles on the foam fibrils. The binding interaction between TiO 2 nanoparticles and melamine foam was enhanced by carbonization. The carbonized 3D framework of melamine foam improved the thermal stability of TiO 2 nanoparticles and prevented TiO 2 nanoparticles from aggregation. The carbonized TiO 2 -coated melamine foam maintained the porous structures of melamine foam and can act as a microreactor for color removal from the dyeing wastewater. The carbonized TiO 2 -coated melamine foam demonstrated the prominent photocatalytic activity on Rhodamine B degradation, with 16 times higher than the non-carbonized counterpart, with 98% of Rhodamine B removed after 60 min of irradiation. More importantly, the carbonized TiO 2 -coated melamine foam removed 90% of dyes in the traditional dyeing wastewater after 120 min under simulated sunlight irradiation, which shows 20 times higher photocatalytic performance than TiO 2 nanoparticles for treating traditional dyeing wastewater. The remarkable photocatalytic performance of the carbonized TiO 2 -coated melamine foam is attributed to the combination of both high light absorption of nitrogen doped carbonized foam and the efficient charge carrier separation promoted by the carbon layer, which inhibited the recombination of electron-hole pairs in TiO 2. The TiO 2 -coated carbon foam can be used as a microreactor, which has promising practical applications in clean production and environmental remediation. Image 1 • Carbonized TiO 2 -coated melamine foam (CTiMF) is fabricated via polydopamine. • Carbonization enhances the binding interaction between TiO 2 and foam. • Microreactors are formed through the 3D framework of the carbonized foam. • CTiMF shows improved catalytic activity for dyeing wastewater compared to TiO 2. [ABSTRACT FROM AUTHOR]

• Occurrence and transformation of phosphonates were revealed in two textile dyeing WWTPs. • Toxicologically critical AMPA was produced during coagulation and biological treatment. • Phosphonates were more readily removed than other DOP fractions in both WWTPs. • Up to 7.81 g/kg phosphonates in sludge may pose potential risks during further disposal. Phosphonates discharged from wastewater treatment plants (WWTPs) have attracted increasing concerns because of their potential impact on eutrophication and potential risks to aquatic ecosystems. However, very few studies are available on their occurrence and transformation in WWTPs, partly due to the lack of sensitive methods for phosphonate analysis in complex matrices. Herein, based on our recent progress in phosphonate analysis, the occurrence and transformation of phosphonates along the full-scale wastewater treatment processes of two textile dyeing WWTPs were revealed. A set of typical phosphonates, including six phosphonate chelators (PCs) and four potential degradation products of PCs (DP-PCs) were quantified in different units and the final dewatered sludge. Three PCs (2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC), 1-hydroxyethane 1,1-diphosphonic acid (HEDP) and nitrilotris(methylene phosphonic acid) (NTMP)) at upmost mg/L and a considerable amount of four DP-PCs (9.12–608 μg/L) were detected in the influents of both WWTPs. In the subsequent treatment, NTMP could be removed more efficiently than PBTC and HEDP, especially in the coagulation unit, and the dissolved phosphonates were eliminated more readily than other dissolved organic phosphorus fractions. Of particular note, the toxicologically critical DP-PC (i.e., aminomethylphosphonic acid) was produced during the coagulation and biological treatment units. The final precipitation unit seemed essential to ensure satisfactory removal of PCs and DP-PCs. In addition, a significant accumulation of phosphonates in dewatered sludge (up to 7.81 g/kg) and the widespread occurrence of harmful DP-PCs also reminded us to pay more concerns on their potential risks during further sludge disposal in future. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Textile industry wastewater includes organic dyes and decomposition products which could have toxic and mutagenic effects on life. The majority of industries in this sector use nonbiodegradable, heat-resistant, light, oxidizing agents and therefore synthetic dyes that are difficult to remove color. In this study, Dianix Yellow Brown CC (0.22%), Dianix Rubine CC (0.79%) and Setapers Blue CE3R (0.015%) containing disperse dye have been used in the production of wastewater from the dyehouse. In this study, textile wastewater has been treated which has applied adsorption and photocatalytic methods by using nano-titanium dioxide (nTiO2). Optimum chemical oxygen demand (COD) and color removal efficiencies have been determined for these two methods. Moreover, under the optimum conditions in the adsorption method, the COD removal efficiency has been obtained as 58.07% and also color removal efficiencies have been obtained as 95.24%, 95.15%, 96.83% for 436, 525 and 620 nm, respectively (pH 2, nTiO2 dose 2.5 g L-1 and 30 min reaction time). Therefore, under the optimum conditions in the photocatalytic method the COD removal efficiency has been obtained as 57.59% and also color removal efficiencies have been obtained as 95.24%, 96.31%, 94.71% for 436, 525 and 620 nm, respectively (pH 2, nTiO2 dose 1.5 g L-1 and 60 min reaction time). Four different kinetic, that is, first-order kinetic, second-order kinetic, pseudo-first-order, pseudo-second-order, models have been used for the processes adsorption and photocatalytic. The pseudo-second-order kinetic model has been found to be the most suitable model for both processes. As a result, regression coefficients (R²) has been obtained for adsorption as 1 and for photocatalytic as 0.9999 and reaction rate constants (k) have been obtained for adsorption as 6.9 × 10-4 L mg-1 min-1 and for photocatalytic as 2.2 × 10-3 L mg-1 min-1. [ABSTRACT FROM AUTHOR]

High-salt dyeing wastewater would do harm to both the environment and people's health. Herein, a photocatalytic solar evaporator with bifunctions of photothermal evaporation and photocatalysis was prepared by loading MnO 2 and TiO 2 on the cotton fabric, aiming at simultaneous pure water derivation and dye degradation. The evaporator was positioned in a slide-shaped configuration that uses downward capillary force and gravity-assisted water transportation for a sufficient water supply, avoiding salt accumulation during photothermal evaporation and realizing a fast dynamic dye removal via photocatalysis. Interestingly, the loaded TiO 2 enhances the photothermal activity of the loaded MnO 2 by increasing light absorption. While MnO 2 also enhances the photocatalytic activity of TiO 2 by charge transfer and heat generation. It was exciting to find that the solution streaming down dynamically through the slide-shaped evaporator into the downstream container was completely colorless, which was in sharp contrast with the blue dye solution at the upstream. Under one sunlight, the evaporator showed a evaporation rate of 1.65 kg m−2 h−1, a photothermal conversion efficiency of 96.65 % and a methylene blue removal efficiency of >95 % during the 8-day evaporation. This study realizes the synergistic effect of photothermal evaporation and photocatalysis, providing a novel strategy for the treatment of high-salt dyeing wastewaters. [Display omitted] • Slide-shaped cotton-based photocatalytic solar evaporator with MnO 2 and TiO 2 for simultaneous desalination and dye removal • TiO 2 strengthened by MnO 2 in photocatalytic activity via charge transfer and heat generation • MnO 2 strengthened by TiO 2 in photothermal evaporation via enhanced light absorption • Zero salt aggregation via capillary effect and gravity-assisted water supply in a slide-shaped structure • Fast dynamic degradation of the dye solution flowing through the slide-shaped evaporator during solar evaporation [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel dual-layer membrane combining a PSF bottom layer and a PH surface layer incorporated with ZIF-71 nanoparticles was developed. • The dual-layer ZIF-71/PH-PSF membrane possessed high permeate flux. • The dual-layer ZIF-71/PH-PSF membrane exhibited high efficiency for dyeingwastewater treatment. • The mechanism underlying the enhanced MD performance of the ZIF-71/PH-PSF membrane was elucidated. Membrane distillation (MD) is a promising technology for the treatment of hypersaline dyeing wastewater. However, commercial membranes still have limitations such as low permeate flux, membrane fouling, and membrane wetting issue in MD process. Herein, a dual-layer MD membrane was fabricated with a polysulfone (PSF) bottom layer and a poly(vinylidene fluoride-co-hexafluoropropylene) (PH) hydrophobic surface layer incorporated with ZIF-71 nanoparticles. The addition of ZIF-71 was optimized based on the results of surface morphology, contact angle, and MD performance. The incorporation of ZIF-71 nanoparticles into PH nanofiber membranes, along with their dual-layer structure, has led to notable improvements in both permeate flux and rejection performance. The fouling resistance of membrane was further evaluated with model dyeing wastewater as feed solution, which contained four types of dyes and heavy metal antimony. The MD performance of the optimized membranes was also measured with real dyeing wastewater as feed solution. The dual-layer membrane decorated with ZIF-71 nanoparticles significantly outperformed the pristine membrane in treating real dyeing wastewater, exhibiting potential for practical applications. Finally, the underlying mechanism on the improved permeate flux and rejection was elucidated systematically. [ABSTRACT FROM AUTHOR]

In this work, the occurrence and removal of polycyclic aromatic hydrocarbons (PAHs) were investigated in a combination process of anoxic baffled reactor (ABR)-hybrid coagulation/membrane bioreactor (HCMBR) for real textile dyeing wastewater treatment. It was found that the target compounds except for the chrysene, benzo(b)fluoranthene, dibenzo(a,h)anthracene, and benzo(g,hi)perylene occurred widely in raw textile dyeing wastewater, treated effluent and sludge samples. In the raw wastewater, two-ring naphthalene was the dominant compound, while three-ring PAHs predominated in the final effluent. The dominant compounds in the raw sludge samples were phenanthrene, while they were pyrene and indeno(1,2,3-cd)pyrene for final discharge sludge. The combination process achieved over 88% removal for all the PAHs. Low molecular weight (LMW) PAHs might be mainly removed by volatilization, adsorption, and sedimentation in the ABR treatment unit. High molecular weight (HMW) PAHs might be mainly removed by adsorption and sedimentation processes after coagulation and solid–liquid separation in the HCMBR treatment unit. The final discharge of treated textile dyeing wastewater and sludge was biologically safe based on the toxicity evaluation test. [ABSTRACT FROM AUTHOR]