Elimination of organic matter present in wastewaters from the cork industry by membrane filtration

BACKGROUND: The first stage of the cork industrial process generates great volumes of wastewater with moderate to high organic pollutant content that must be purified using different procedures, such as filtration by membranes. RESULTS: The tangential filtration of these wastewaters was studied using two different laboratory equipments. In the first one, three ultrafiltration (UF) membranes were tested, with molecular weight cut‐off (MWCO) 100 kDa and 30 kDa, and two operating modes were used: total recycling of permeate and retentate streams, and in continuous mode, without recycling both streams. In the total recycling UF experiments, the influence of the operating variables on the permeate flux was first established. The effectiveness of the different membranes was determined by evaluating the rejection coefficients for several parameters that measure the global pollutant content of the effluent. The values found for these rejection coefficients were in the following order: ellagic acid and color > absorbance at 254 nm > tannic content > COD (chemical oxygen demand). In the continuous mode experiments, the fouling mechanism for each membrane was established by fitting the experimental data to various filtration fouling models given in the literature. The operating mode in the second equipment was batch concentration, and additional experiments were carried out with an UF membrane (2 kDa), and with a NF membrane (with MWCO in the range 150–300 Da). CONCLUSIONS: The three operating modes tested provided different rejection levels of organic matter; among them, the most effective procedure tested was batch concentration mode using a NF membrane. Copyright © 2007 Society of Chemical Industry     

Flux,antifouling and separation characteristics enhancement of nanocomposite polyethersulfone mixed-matrix membrane by embedding synthesized hydrophilic adipate ferroxane nanoparticles

Polyethersulfone (PES) nanofiltration (NF) membranes were prepared by blending of synthesized hydrophilic adipate ferroxane nanoparticles (AFNPs) as a novel multifunctional nanofiller via the phase inversion method. The water contact angle measurement indicated the higher hydrophilicity of the NF membranes. The water flux of the membranes improved significantly after the addition of AFNPs, from 10.4 to 32.2 kg/m²h. Antifouling characteristics of AFNPs/PES membranes were improved by increased hydrophilicity and decreased membrane surface roughness. The 0.6 wt% AFNPs/PES membrane exhibited the highest FRR (96%) and the lowest irreversible fouling resistance (6%). The nanofiltration performance of the prepared membranes was evaluated by dye removal and salt retention. The results proved the high dye removal capability of modified membranes (98% rejection) compared with the unfilled PES membrane (89% rejection). The salt retention sequence for membrane with 0.2 wt% of nanoparticles was Na₂SO₄ (70%)>MgSO₄ (60%)>NaCl (18%).     

Influence of compatibility between sol and intermediate layer on the performance of yttria-stabilized zirconia nanofiltration membrane

This paper reports the synergistic effect of the sol and intermediate layer on the performance of yttria-stabilized zirconia (YSZ) nanofiltration (NF) membranes. We have focused on the characterization of the microstructure, pure water permeance, and molecular weight cut-off (MWCO) of the NF membranes derived from zirconia sols of different precursor concentrations on two types of supported ZrO₂ ultrafiltration (UF) membranes. We found that the performance of YSZ membranes strongly depends on the sol concentration and the pore size of the intermediate layer. In addition, YSZ gel membrane formation was found to follow the filtration process. Therefore, it is essential to maintain the compatibility between the sol and intermediate layer to fabricate high-performance NF membranes. A crack-free thin YSZ layer with an MWCO of 816 Da (pore size: 1.4 nm) and a water permeance of 25 L m^-2 h^-1 bar^-1 was fabricated using a precursor concentration of 0.03 mol/L, on ZrO₂ UF membrane with a pore size of 5.5 nm. The YSZ NF membrane exhibited a relatively high retention rate towards MgCl₂ (71%), whereas a lower retention rate was observed for NaCl (35%).     

An advanced treatment of high-strength opium alkaloid processing industry wastewaters with membrane technology: pretreatment, fouling and retention characteristics of membranes

This paper presents the results of the laboratory and pilot-scale membrane experiments of opium alkaloid processing industry effluents. Different types of ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO) membranes were evaluated for membrane fouling, permeate flux and their suitability in separating COD, color and conductivity. Experiments demonstrated that membrane treatment is a very promising advanced treatment option for pollution control for opium alkaloid processing industry effluents. Almost complete color removal was achieved with NF and RO membranes. COD and conductivity removals were also greater than 95% and met the current local standards. Nevertheless, pretreatment was an important factor for the NF and RO membrane applications. Membrane fouling occurred with direct NF membrane applications without UF pretreatment. The total estimated cost of the UF and NF treatment system was calculated as $0.96/m³, excluding the concentrate disposal cost.     

The influence of degreasing agents used at car washes on the performance of ultrafiltration membranes

The influence of washing chemicals used at car washes on the flux and retention of three ultrafiltration (UF) membranes has been studied. Eleven commercial degreasing agents, two shampoo agents and a wax were included in the investigation. The membrane performance when treating waste water collected at a car wash at different times of the year was also studied. The retention of the different chemicals varied greatly, but there was no significant difference in COD retention among the three UF membranes. The highest flux was observed when treating the alkaline degreasing agents and the shampoo solutions. The flux and COD retention when treating the waste water from the car wash were 30–50 l/m ² h and 60%, respectively. One of the low-retention degreasing agents was treated by nanofiltration (NF). The retention was significantly higher when using NF, but the COD concentration in the permeate was still too high to allow the permeate to be discharged without further treatment.     

High flux ultrafiltration membranes based on electrospun nanofibrous PAN scaffolds and chitosan coating

Conventional ultrafiltration (UF) or nanofiltration (NF) filters for water treatments are based on porous membranes, typically manufactured by the phase immersion method. The torturous porosity in these membranes usually results in a relatively low flux rate. In this study, we demonstrated a new type of high flux UF/NF medium based on an electrospun nanofibrous scaffold (e.g. polyacrylonitrile, PAN) coupled with a thin top layer of hydrophilic, water-resistant, but water-permeable coating (e.g. chitosan). Such nanofibrous composite membranes can replace the conventional porous membranes and exhibit a much higher flux rate for water filtration. The interconnected porosity of the non-woven nanofibrous scaffold can be controlled partially by varying the fiber diameter (from about 100 nm to a few micrometers) through the electrospinning processing. The example membrane, containing an electrospun PAN scaffold with an average diameter from 124 to 720 nm and a porosity of about 70%, together with a chitosan top layer having a thickness of about 1 μm, although not yet fully optimized, exhibited a flux rate that is an order magnitude higher than commercial NF membranes in 24 h of operation, while maintaining the same rejection efficiency (>99.9%) for oily waste-water filtration.     

Removal of selected pharmaceuticals in waters by photochemical processes

BACKGROUND: Large amounts of pharmaceutical compounds are consumed throughout the world, and after being metabolized in humans are discharged into water streams. Some of them are not completely removed in wastewater treatment plants and, as a result, they are found in some effluents as well as in surface and ground waters. RESULTS: Four pharmaceutical compounds (metoprolol, naproxen, amoxicillin and phenacetin) frequently found in wastewaters were selected to be individually photo‐oxidized in ultra‐pure water by monochromatic UV radiation. The influence of independent variables (pH, temperature, and additional presence of hydrogen peroxide) was established, and first‐order rate constants and quantum yields evaluated. The compounds were also oxidized using Fenton's reagent and, after establishing the influence of the operating conditions (ferrous ions and hydrogen peroxide concentrations, pH and additional presence of UV radiation), the rate constants for the radical reaction between each pharmaceutical and hydroxyl radicals were determined. Finally, the simultaneous photo‐oxidation of mixtures of the selected pharmaceuticals in several types of water (commercial mineral water, groundwater and reservoir water) was performed by means of UV radiation alone and by the combination UV/H₂O₂. The influence of the independent variables in these processes was discussed, and the kinetic study allowed the determination of various rate constants for each compound. CONCLUSION: As the pharmaceutical concentrations theoretically calculated by the proposed kinetic model agree well with the experimental results obtained, this model constitutes an excellent tool to predict the elimination of these compounds when they are present in different natural waters. Copyright © 2009 Society of Chemical Industry     

多孔陶瓷膜用于碳量子点的分离与纯化

尺寸分布均一的碳量子点由于其良好的光学特性,在光电设备、离子检测、纳米传感器、生物成像和催化剂等领域具有广阔的应用前景。采用陶瓷膜“超滤-纳滤”双膜法,对微波合成的碳量子点进行分离和纯化。研究了pH对碳量子点料液荧光强度和粒径分布的影响。在pH=3时,碳量子点分散较好,荧光强度较高。陶瓷超滤膜可以有效截留碳量子点料液中的大颗粒杂质,渗透侧的碳量子点平均粒径约为2 nm,分散良好,无团聚现象。陶瓷纳滤膜对碳量子点具有良好的截留性能,在浓缩和水洗过程中可以进一步去除料液中的小分子杂质。经双膜法处理后,发射光谱由多峰分布变为单峰分布,且峰宽变窄,碳量子点的发光纯度得到了明显提高。     

Nanofiltration and reverse osmosis thin film composite membrane module for the removal of dye and salts from the simulated mixtures

Nanofiltration (NF) and reverse osmosis (RO) thin film composite polyamide membrane modules were used to remove the color from the contaminated solution mixture. The feasibility of membrane processes for treating simulated mixture by varying the feed pressures (100-400 psi) and feed concentrations was studied to assess the separation performance of both NF and RO membranes. It was found that the efficiency of NF and RO membranes used in the treatment of colored water effluents was greatly affected by the presence of salts and dyes in the mixture. Color removal by NF with a high rejection of 99.80% and total dissolved solids (TDS) of 99.99% was achieved from RO by retaining significant flux rate compared to pure water flux, which suggested that membranes were not affected by fouling during the simulated wastewater process operation. The effect of varying concentrations of Na₂SO₄ salt and methyl orange (MO) dye on the performance of spiral wound membranes was determined. Increasing the dye concentration from 500 to 1000 mg/L resulted in a decrease of salt rejection at all operating pressures and for both concentrations of 5000 and 10,000 mg/L as the feed TDS. Increasing the salt concentration from 5000 to 10,000 mg/L resulted in a slight decrease in dye removal.     

Impact of pH on the removal of fluoride, nitrate and boron by nanofiltration/reverse osmosis

The objective of this study was to evaluate the impact of pH on boron, fluoride, and nitrate retention by comparing modelled speciation predictions with retention using six different nanofiltration (NF) and reverse osmosis (RO) membranes (BW30, ESPA4, NF90, TFC-S, UTC-60, and UTC-80A). Retention was explained with regard to speciation, membrane properties, and ion properties such as charge, hydrated size, and Gibbs energy of hydration. Flux was independent of pH, indicating that pH did not alter pore size and hence permeability for all membranes except UTC-60. Membrane charge (zeta potential) was strongly dependent on pH, as expected. Boron and fluoride retention depended on membrane type, pH, which correlated closely to contaminant speciation, and was due both to size and charge exclusion. While retention at low and neutral pH was a challenge for boron, high boron retention was achieved (> 70% above pH 11). Fluoride retention was generally > 70% above pH 7. Nitrate retention depended on membrane, and was mostly pH independent (as was the speciation). The presence of a background electrolyte matrix (20 mM NaCl and 1 mM NaHCO₃) reduced nitrate and boron retention (at high pH) due to charge shielding, and enhanced the retention of fluoride in single feed solutions, suggesting preferential transport of Cl⁻ compared to F⁻ with Na⁺.     

Adsorption of hydrophilic and hydrophobic pharmaceuticals on RO/NF membranes: Identification of interactions using FTIR

This article examines the adsorption of pharmaceuticals on reverse osmosis (RO) and nanofiltration (NF) membranes. The membranes were characterized in terms of Fourier transformation infrared (FTIR) spectra, surface charge, hydrophobicity, pore size distribution, and roughness. Five pharmaceuticals were used to determine their rejection and possible interactions with the membranes. Albendazole, a hydrophobic pharmaceutical, adsorbed on the NF (NF270) and RO (XLE) membranes. FTIR spectra showed significant changes (new peaks/bonds) on the membranes, confirming that adsorption plays an important role in the overall mechanism of rejection in the case of hydrophobic compounds. Hydrophilic pharmaceuticals (sulfaguanidine, trimethoprim, hydrocortisone, and procaine) did not adsorb on the XLE membrane, showing that size exclusion and electrostatic repulsion were both dominant removal mechanisms. This article gives new insights into NF membranes in the treatment of hydrophilic compounds. The results clearly show the adsorption of hydrophilic compounds on the NF membranes since H‐bonds and π–π interactions were observed on their FTIR spectra. Therefore, both the hydrophobic and the hydrophilic adsorption have to be taken into account when considering the removal mechanism, especially in the case of NF membranes. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44426.     

Application on to nanofiltration to water management options for oil sands operation

A membrane separation process, nanofiltration (NF), has been applied successfully for treatment of oil sandswaters, particularly to water softening and removal of toxic components. This study focused on the selection of appropriate membranes and the assessment of their performance for the removal of polyvalent ions (hardness) and naphthenic acids (NA) (the main acute toxicant in oil sands process-affected imported waters) from both imported and potential discharge waters. Experiments were carried out using a bench-scale flat sheet membrane system with several commercially available NF membranes. It was found that after membrane filtration, both water hardness and the NA concentrations were reduced significantly (>95%). A permeate flux was maintained at 15 L/m²/h or higher, with a retentate volume of about 10% of the feed volume.     

PVA/OPD改性膜对微生物燃料电池性能的影响

为提高微生物燃料电池（MFC）的性能，以聚乙烯醇（PVA）为黏合剂，分别以磷钨酸（PWA）和邻苯二胺（OPD）为改性剂，采用溶液浸渍法制备了PVA/PWA和PVA/OPD改性膜并搭载于MFC系统，以SEM、电化学阻抗谱（EIS）、循环伏安法（CV）、吸水率表征了膜的性能，并考察膜改性对MFC产电量和化学需氧量（COD）去除率的影响。结果显示，PVA/PWA和PVA/OPD改性膜均能在一定程度上提升MFC性能，但PVA/OPD改性膜效果更佳。PVA/OPD改性膜的吸水率为14.49%，较常规Nafion 117膜（NF）提高了126.05%。采用PVA/OPD改性膜的MFC在测试周期内的产电量为101.75 J，较采用NF时提高了587.50%；对阿莫西林制药废水的COD去除率为66.2%，较采用NF时提高了48.4%。基于PVA/OPD的膜改性方法对提高MFC的产电性能和废水处理效果有显著作用。     

Silicate and zirconium phosphate modified Nafion/PTFE composite membranes for high temperature PEMFC

The PEMFC performance of MEAs prepared from Nafion-212 (thickness 50 μm, Du Pont Co), porous poly(tetrafluoro ethylene) (PTFE, thickness 15 ~ 18 μm) film reinforced Nafion (NF, thickness 20 ± 2 μm), silicate hybridized NF (NF-Si, thickness 21 ± 2 μm), and zirconium phosphate hybridized NF (NF-Zr, thickness 21 ± 2 μm) membranes were investigated at 110 °C/ 51.7% RH, 120 °C/ 38.2% RH, and 130 °C/ 28.6% RH. We show PEMFC performances of these MEAs decrease in the sequence of: NF-Zr> NF-Si> NF> Nafion-212. The NF, NF-Si, and NF-Zr membranes have lower membrane thickness and lower Nafion content and require less water for proton transport than Nafion-212 at temperatures above 110 °C, and thus have higher conductivity and better PEMFC performance than Nafion-212. Incorporating silicate and zirconium phosphate into NF membranes enhances water retention of membranes at temperatures above 110 °C and improves PEMFC performances. Besides enhancing water retention, incorporating zirconium phosphate into membranes also provides more routes for proton transport via H⁺ exchange between H₃ ⁺O and HPO₄-Zr- and between H₂ ⁺PO₄-Zr- and HPO₄-Zr-. Thus NF-Zr has a higher conductivity and better PEMFC performance than NF and NF-Si.     

Removal of natural organic matter by ultrafiltration and nanofiltration for drinking water production

Water from Lake Butoniga near the town of Buzet, Croatia, was used as a source for drinking water production. Since lake water has a high concentration of trihalomethane precursors, a treatment was necessary. A process including ozonation, flocculation and filtration was chosen on the basis of preliminary work in a trial pilot plant with a capacity of 10 m³ h⁻¹. Although the chosen process succeeded in producing water that met the demands for drinking water, the efficiency of the removal of natural organic matter was relatively low. Ultrafiltration (UF) and nanofiltration (NF) processes were investigated as alternatives and possible upgrades of the process. Experiments were conducted at pilot plants with the Mavibran SP 006A and Romicon PM 10, PM 50, GM 80 and PM 500 OF membranes as well as with the Filmtec NF 45 NF membrane. Since most of the organic matter in the lake water was smaller than 6-8 kD, the use of the NF process was proposed. To avoid fouling of the NF membrane, we used flocculated and filtrated water from the trial plant as NF feed water. This combination produced water of high quality while process parameters remained stable over the entire period of investigation.     

Water Quality Improvement by Combined UF,RO, and Ozone/Hydrogen Peroxide System (HiPOx) in the Water Reclamation Process

Conventional water reclamation processes, such as membrane bioreactors, are not always effective in removal of pharmaceuticals and personal care products (PPCPs), endocrine disrupting chemicals (EDCs) and/or N-nitrosodimethylamine (NDMA), even with the reverse osmosis (RO) membrane process. A study was conducted, at a NEWater factory in Singapore, to compare a conventional ultrafiltration (UF) membrane /RO treatment process with a treatment train having the HiPOx unit, an advanced oxidation process (AOP), which was installed between the UF and the RO unit operations. By incorporating the HiPOx into the UF/RO treatment process, following results were observed; 1) increased removal of PPCPs, EDCs and NDMA, 2) improvement in ultraviolet transmission (UVT) of the RO permeate, 3) enhanced removal of TOC and color, and increased UVT of the RO brine, 4) suppression of the increase in the RO transmembrane pressure by organic fouling.     

膜技术在饮用水除砷中的应用研究进展

以低压驱动膜的微滤膜(MF)与超滤膜(UF),和高压驱动膜的反渗透膜(RO)与纳滤膜(NF)为主,分析了目前国内外膜技术在饮用水除砷方面的效果、影响因素、浓水处理、膜污染及其清洗等方面的应用研究和进展情况,同时对膜技术优缺点及其在除砷中的应用研究方向与前景做了展望.     

Evaluation of the possibility of utilization of poly(amidesulfonamide)s (PASAs) in ultrafiltration technology

Ultrafiltration (UF) membranes of six selected poly(amidesulfonamide)s (PASAs) were prepared and studied. The pure water flux and the retention of albumin (bovine serum) were used to evaluate the quality of the UF performance of the fabricated membrane. Membranes with good mechanical strength were obtained by using the phase inversion method. A comparison of the UF performance of the PASA membranes fabricated from a casting solution containing 12% w/w PASAs and 4% w/w lithium bromide in dimethylacetamide was made. The best retention of albumin (bovine serum) by membranes prepared under the conditions studied from the selected homopolymers of PASAs, and their corresponding pure water flux at 0.207 MPa, ranged from 84.6 to 100% and 120 to 396 L m⁻² h⁻¹, respectively. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 2087–2093, 1998     

Pilot-scale spiral wound membrane assessment for THM precursor rejection from upland waters

The outcomes of a pilot-scale study of the rejection of trihalomethanes (THMs) precursors by commercial ultrafiltration/nanofiltration (UF/NF) spiral-wound membrane elements are presented based on a single surface water source in Scotland. The study revealed the expected trend of increased flux and permeability with increasing pore size for the UF membranes; the NF membranes provided similar fluxes despite the lower nominal pore size. The dissolved organic carbon (DOC) passage decreased with decreasing molecular weight cut-off, with a less than one-third the passage recorded for the NF membranes than for the UF ones.

The yield (weight % total THMs per DOC) varied between 2.5% and 8% across all membranes tested, in reasonable agreement with the literature, with the aromatic polyamide membrane providing both the lowest yield and lowest DOC passage. The proportion of the hydrophobic (HPO) fraction removed was found to increase with decreasing membrane selectivity (increasing pore size), and THM generation correlated closely (R² = 0.98) with the permeate HPO fractional concentration.     

Comparison of ceramic and polymeric membranes for natural organic matter (NOM) removal

Ceramic membranes were compared with polymeric membranes with respect to natural organic matter (NOM) removal using two removal mechanisms (i.e., size exclusion and charge repulsion). NOM properties including molecular weight and molecular structure, at different charge densities, were examined, along with membrane characteristics, including molecular weight cut-off (MWCO) and surface charge. Integrated analyses of both NOM and membrane characteristics provided information for membrane evaluation of different membrane materials and configurations (i.e., tubular vs. flat sheet type). A ceramic tight-ultrafiltration (UF) membrane showed the same potential as a similar nanofiltration (NF) polymeric membrane, in terms of the minimization of haloacetic acid (HAA) formation. Moreover, a ceramic OF membrane with a MWCO of 8000 Daltons showed almost the same behavior as an equitable polymeric UF membrane with a MW CO of 8000 Daltons in terms of NOM removal.