BW30 Membrane Research Articles

Improved Flux Performance in Brackish Water Reverse Osmosis Membranes by Modification with ZnO Nanoparticles and Interphase Polymerization.

With each passing year, water scarcity in the world is increasing, drying up rivers, lakes, and dams. Reverse osmosis technology is a very viable alternative which helps to reduce water shortages. One of the challenges is to make the process more efficient, and this can be achieved by improving the capacity by adapting membranes with nanomaterials in order to increase the permeate flux without exceeding the limits established in the process. In this research, brackish water membranes (BW30) were modified with ZnO nanoparticles by interphase polymerization. The modified membranes and BW30 (unmodified) were characterized by FTIR, AFM, contact angle, and micrometer. The membranes were tested in a cross-flow apparatus using 9000 ppm brackish water, and their permeate flux, salt rejection, and concentration polarization were determined. The salt rejection for the 10 mg ZnO NP membrane was 97.13 and 97.77% at 20 and 30 Hz, respectively, sufficient to generate drinking water. It obtained the best permeate flux of 12.2% compared to the BW30 membrane with 122.63 L m-2 h-1 at 6.24 MPa and 30 Hz, under these conditions, and the concentration polarization increased.

Recovery of Chromium and Two Solvents (Dichloromethane-DCM Tetrachloroethane-TCE) Using Nanofiltration and Reverse Osmosis Membranes from Leather Industry Wastewater

In this study, for removal of the leather industry pollutants and to recovery of chromium (Cr), dichloromethane (DCM) and tetrachloroethane (TCE) two sequential nanofiltration (NF) (NF90 and NF270) and two reverse osmosis (RO) (BW30 and SW30) reactor membranes were used. The membrane surface properties were investigated by Fourier Transform Infrared Spectroscopy-Attenuated Total Reflectance (FTIR-ATR) and Scanning Electron Microscopy (SEM). The permeate of the SW30 reverse osmosis exhibited high removals varying between 98% and 99% for sodium ion (Na+ ), potassium ion (K+ ), magnesium ions (Mg2+), calcium ions (Ca2+), total chemical oxygen demand (CODtotal), dissolved chemical oxygen demand (CODdis), dissolved organic carbon (DOC) and inert chemical oxygen demand (inert COD), Chromium (Cr3+ ), Dichloromethane and Tetrachloroethane. In the NF90 nanofiltration process lower removals were detected (96%-97%) for all pollutants mentioned above. The effluent of reverse osmosis with a BW30 membrane match to the Turkish Water Pollution Control Regulation rules for treated water discharged to the receiving environment while SW30 reverse osmosis membrane was perfect for ultimate treatment of the pollutants present in the leather industry discharges. From the concentrate of the SW30 reverse osmosis, 945 mg/l chromium, 460 mg/l dichloromethane and 360 mg/l tetrachloroethane were reused. The performance and recoveries of Cr and two solvents (DCM and TCE) data in NF and RO membrane reactors were evaluated with Artificial Neural Network (ANN) process and Kruskal Wallis test statistic coupled with Mann-Whitney U statistic in this study.

Removal of multiple pesticides from water by different types of membranes

Pesticides are used in agriculture to protect crops from pathogens, insects, fungi and weeds, but the release of pesticides into surface/groundwater by agriculture runoff and rain has raised serious concerns not only for the environment but also for human health. This study aimed to investigate the impact of surface properties on the performance of seven distinct membrane types utilized in nanofiltration (NF), reverse osmosis (RO) and forward osmosis (FO) processes in eliminating multiple pesticides from spiked water. Out of the membranes tested, two are self-fabricated RO membranes while the rest are commercially available membranes. Our results revealed that the self-fabricated RO membranes performed better than other commercial membranes (e.g., SW30XLE, NF270, Duracid and FO) in rejecting the targeted pesticides by achieving at least 99% rejections regardless of the size of pesticides and their log Kow value. Despite the marginally lower water flux exhibited by the self-fabricated membrane compared to the commercial BW30 membrane, its exceptional ability to reject both mono- and divalent salts renders it more apt for treating water sources containing not only pesticides but also various dissolved ions. The enhanced performance of the self-fabricated RO membrane is mainly attributed to the presence of a hydrophilic interlayer (between the polyamide layer and substrate) and the incorporation of hydrophilic nanosheets in tuning its surface characteristics. The findings of the work provide insight into the importance of membrane surface modification for the application of not only the desalination process but also for the removal of contaminants of emerging concern.

Investigation of reusability of effluents from an organized industrial zone wastewater treatment plant using a pressure-driven membrane process

Abstract The quantity of wastewater being discharged into the environment due to the rise in industrial activities is progressively growing over time. Aside from large environmental risk posed by untreated wastewater discharge, the reuse of treated water prevents wastage of large amounts of water. For this reason, in this study, the reuse potential of an organized industrial zone wastewater was investigated by membrane processes. The appropriate membrane type and rejection performance were determined for various pollutant parameters including conductivity, chemical oxygen demand (COD), total nitrogen (TN), chloride, and sulfate. Laboratory-scale batch membrane filtration experiments were performed by using three different membrane types (BW30, XLE, and X20). The experiments were conducted at 15 and 20 bar pressures and flux data were collected during the operations. The results showed that BW30 and X20 membranes could be operated comfortably with 80% recovery for the wastewater containing low and high sulfate concentrations. For the wastewater with low sulfate concentration, the fluxes of BW30 and X20 at 20 bar were 19.7 and 16.4 L/m2/h, respectively, at 80% recovery. On the other hand, for the wastewater with higher sulfate concentration, the fluxes of BW30 and X20 at 20 bar were 8.6 and 11.5 L/m2/h, respectively.

An integrated process for wet scrubber wastewater treatment using electrooxidation and pressure-driven membrane filtration

In this study, the electrooxidation (EO) and membrane processes were used for chemical oxygen demand (COD) and total phenol (TPh) removal from wet scrubber wastewater (WSW). EO experiments were carried out using Al, Fe, SS, Ti, graphite, active carbon cloth electrodes and Box-Behnken design were used for optimization of maximum COD and TPh removal efficiency. Moreover, membrane filtration experiments were conducted to EO process using nanofiltration (NF270) and reverse osmosis membranes (SW30 and BW30). The maximum COD (55%) and TPh (50%) removal efficiency was achieved at pH of 8, 150 A/m2 current density, and 180 min reaction time in EO process. Membrane filtration results showed that COD removal efficiency was the highest for SW30 membrane (95.18%) compared to BW30 (91.15%) and NF270 (80.11%) membranes. TPh removal efficiency in the NF270, BW30, and SW30 membranes was 27.08%, 96.06%, and 98.02%, respectively. The effect of microbial cell viability of the raw and treated wet scrubber wastewater after electrooxidation and membrane filtration was also investigated using E. coli. In addition to these, biofilm inhibition of the raw wet scrubber wastewater and the treated WSW after EO and membrane filtration were tested and the highest biofilm inhibition was found as 76.43% and 72.58% against S. aureus and P. aeruginosa, respectively, in 1/20 diluted samples of the raw WSW. This study suggests that the integrated process using EO and pressure-driven membrane methods are an efficient strategy for COD and TPh removal from WSW.

Water recovery from yarn fabric dyeing wastewater using electrochemical oxidation and membrane processes.

This study intended to evaluate and compare the efficiency of electrochemical oxidation (EO), nanofiltration (NF), and reverse osmosis (RO) membranes processes in the treatment of yarn fabric dyeing wastewater (YFDW) in terms of chemical oxygen demand (COD) removal, color removal, salinity reduction, and conductivity removal. EO tests of the textile effluent were conducted under various current densities and solution pH conditions employing a graphite electrode. Membrane filtration experiments were conducted using two different NF membranes: NP010 and NP030 and two distinct RO membranes: BW30 and SW30 flat-sheet membranes. The experimental results showed that NF membrane process is not suitable for yarn fabric wastewater treatment showing low removal efficiencies for COD, color, and conductivity. However, both EO and RO membranes could reduce COD and color to high removal performances. EO results showed more than 99% of color removal and 80% of COD elimination at pH = 6 and current density of 50 mA/cm2 after 180 min of reaction. Using RO membrane for yarn fabric wastewater treatment demonstrated relatively complete removal of color concentration and 98% of COD elimination. However, EO process showed less performance in conductivity removal efficiency compared to the RO membranes. EO treatment of YFDW decreased conductivity by 31.2%, whereas RO membrane process reduced conductivity to a greater extent and recorded 97.1% of removal elimination percentage. Therefore, the treated water by RO membrane could be recycled back to the process such as washing and dyeing, in that way offering economic profits by decreasing water consumption and wastewater treatment cost. PRACTITIONER POINTS: Electrochemical oxidation and membrane filtration processes were combined for the treatment of yarn fabric dyeing wastewater (YFDW). A 100% color removal of color and 98.5% COD elimination efficiencies were obtained for the electrochemical oxidation (EO) + RO combined process. EO treatment of YFDW decreased conductivity by 32.7%, whereas the RO membrane process reduced conductivity to a greater extent and recorded 97.7% of removal elimination percentage.

Enhanced Desalination Polyamide Membranes Incorporating Pillar[5]arene through in-Situ Aggregation-Interfacial Polymerization-isAGRIP.

Membrane-based desalination have an important role in water purification. Inspired by highly performant biological proteins, artificial water channels (AWC) have been proposed as active components to overcome the permeability/selectivity trade-off of desalination processes. Promising performances have been reported with Pillararene crystalline phases revealing impressive molecular-scale separation performances, when used as selective porous materials. Herein, we demonstrate that Pillar[5]arene PA[5] aggregates are in-situ generated and incorporated during the interfacial polymerization, within industrially relevant reverse osmosis polyamide-PA membranes. In particular, we explore the best combination between PA[5] aggregates and m-phenylenediamine (MPD) and trimesoylchloride (TMC) monomers to achieve their seamless incorporation in a defect-free hybrid polyamide PA[5]-PA membranes for enhanced desalination. The performances of the reference and hybrid membranes are evaluated by cross-flow filtration under real reverse osmosis conditions (15.5 bar of applied pressure) by filtration of brackish feed streams. The optimized membranes achieve a ∼40 % improvement, in water permeance of ∼2.76±0.5 L m-2 h-1 bar-1 and high 99.5 % NaCl rejection with respect to the reference TFC membrane and a similar water permeance compared to one of the best commercial BW30 membranes (3.0 L m-2 h-1 bar-1 and 99.5 % NaCl rejection).

Bio-based succinic acid recovery by ion exchange resins integrated with nanofiltration/reverse osmosis preceded crystallization

Succinic acid is a key platform chemical for production of various products such as biodegradable polymers, pharmaceuticals, fine chemicals and foods. In the present study, bio-based succinic acid was recovered through two processes. Process I consisted of chromatographic separation with anionic exchange resin followed by direct crystallization, whereas process II sequentially consisted of cationic exchanger, activated carbon, NF/RO membrane, vacuum distillation, and crystallization. The highest chromatographic separation efficiency for succinic acid by Amberlite IRA900 Cl column was calculated as 69.3% at flow rate of 0.42BV/h. Rejection of succinic aid (SA), lactic acid (LA), formic acid (FA) and acetic acid (AC) by NF90 membrane was 53.1, 51.8, 46.6 and 39.8%, respectively at pH less than 2. However, at pH 6.8 the respective rejections increased to 96.8, 90.6, 71.3 and 70.5%. Double pass with BW30 or HP reverse osmosis membranes achieved retention of SA, LA, FA and AC of 95.9%, 95.8%, 65.4% and 46.9%, respectively. Analysis of generated SA crystals by X-ray diffraction technique (XRD) and Fourier transform infrared (FTIR) showed the crystallinity of recovered SA as conformable to standard grade crytsals. The purity of generated succinic acid crystals was recorded as 98.5% and 96.7% for process I and process II, respectively. The calculated succinic acid yield was 78% for process I and 65% for process II. Herein, we demonstrated two alternative systems for bio-based succinic acid recovery, which will set a stage for research in efficient downstream purification of SA.

Enhanced treatment of perfluoroalkyl acids in groundwater by membrane separation and electrochemical oxidation

This work explores the treatment of poly- and perfluoroalkyl acids (PFAAs) in groundwater by coupling membrane separation and electrochemical oxidation (ELOX). A process system engineering approach based on modelling and empirical data was followed. Two nanofiltration (NF90) and reverse osmosis (BW30) membranes were characterized for treating an electrolyte (NaCl and CaSO4) mixture of perfluorocarboxylic acids (PFCAs) containing PFOA, PFHpA, PFHxA, PFPeA and PFBA with initial concentrations of 10 µg L−1 each. Membrane surface charge shielding and concentration polarization negatively influenced NF90 performance, and the BW30 membrane was selected. Electrochemical oxidation with boron doped diamond anodes treated the PFCAs mixture amended with PFOS and 6:2 FTSA, emulating previously pre-concentrated feed and non-preconcentrated feed conditions. Working at different current densities (J) between 20 and 350 A m−2, the removal of PFOA, PFOS and 6:2 FTSA followed first order apparent kinetics, although shorter chain PFCAs initially showed increasing trends because of their simultaneous electrogeneration and degradation. Overall, ΣPFAA electrolysis followed first order kinetics linearly correlated to J in the full range of testing. Unexpectedly, PFAAs electrolysis was faster for the low conductive non-preconcentrated feed, a result that was ascribed to the enhanced direct electron transfer mechanism resulting from the higher cell voltage. For 99.9% PFAAs removal, the total specific cost of treatment was minimized using a cascade of four RO stages and ELOX treatment of the concentrate, to reach ΣPFAA below the Health Advisory Levels recommended by the USEPA in drinking water (<70 ng L−1 sum of PFOA and PFOS).

Investigation of plasticizer production industry wastewater treatability using pressure-driven membrane process

Abstract In this study, the treatability of plasticizer production industry wastewater was investigated using nanofiltration (NF) and reverse osmosis (RO) membranes. The effect of operating pressure, pH of the wastewater, and sequential treatment option on the permeate flux, COD, phthalate, and micropollutant removal efficiencies were examined. The steady-state permeate fluxes of NF270, NF90, and BW30 membranes were 47.1, 19.0, and 13.9 L/m2/h for 15 bar, respectively. Sequential filtration using NF90 and BW30 membranes to protect the RO membrane was also tested. The initial and steady-state permeate fluxes were 30.4 and 18.9 L/m2/h, respectively, for 15 bar. The effect of wastewater pH in the range 4.0–10.0 was also studied and maximum initial and steady-state permeate fluxes were obtained at pH = 10.0. The permeate quality of NF90 and NF90 + BW30 membranes operated at 15 bar was measured and they showed a high degree for phthalate removal from wastewater from 97.7% to 99.9%. Moreover, a high degree of micropollutants was also obtained from 88.4% to 99.9% for sequential filtration (NF90 + BW30). The COD reduction efficiencies were obtained at 15 bar as 23.3%, 81.5%, and 87.6% for individual NF270, NF90, and BW30 membranes, respectively. However, COD reduction efficiency was increased up to 90.8% when sequential filtration (NF90 + BW30) was applied.

Treatment of organized industrial zone wastewater by microfiltration/reverse osmosis membrane process for water recovery: From lab to pilot scale

The global increase in industrialization has resulted into water scarcity. Research on water use efficiency and water reclamation is paramount in addressing this scarcity. In this study, laboratory and on-site pilot scale tests were conducted for water recovery from an industrial wastewater treatment plant. Different RO membranes (BW30, HP, and LE) were investigated with chemical treatment and ceramic microfiltration (MF) as pretreatment steps. Laboratory studies were conducted in dead-end filtration mode, whereas pilot scale studies were performed in cross flow mode with two spiral wound membranes. The removal efficiencies ranged from 40.0-86.3% for COD, 97.6- 99% for SO42-, 69.2-94.9% for Cr ion, 89.3-100% for Pb ion, 66.3-98.2 for Fe ion, 97.5- 99.7% for Zn ion, 95.1-99.5% for Si ion, and 79.1-100% for total phosphorus (TP). For the laboratory studies with 80% water recovery, the permeate flux reduced from 27.2 to 7.1 L/m2h, 35.7 to 1.3 L/m2h and 25.6 to 0.8 L/m2h for BW30, LE, and HP, respectively. On the other hand, four different operation modes were investigated to determine the effect of each mode on membrane performance and fouling properties. Average permeate flux of 18.7 and 21.3 L/m2h, 12.7 and 12.8 L/m2h, 13.4 and 14.6 L/m2h, 12.5 and 14.1 L/m2h were recorded for LE and BW30 membranes in the first, second, third, and fourth modes, respectively. Membrane autopsies were performed by atomic force microscopy (AFM), scanning electron microscopy (SEM), and energy dispersive X-rays (EDX). The system was effective in recovering the permeate to required industrial cooling and boiler water quality.

Removal of herbicide 2-methyl-4-chlorophenoxyacetic acid (MCPA) from saline industrial wastewater by reverse osmosis and nanofiltration

Conventional reverse osmosis (RO), a novel temperature-swing RO (TSRO), and tailored nanofiltration (NF), were investigated to target the removal of the chlorophenoxy broad-leaf herbicide 2-methyl-4-chlorophenoxyacetic acid (MCPA) from saline (HCl-rich) wastewater at pH between 1 and 2. Batch concentration by RO at 17.5 bar using BW30 and SW30 membranes showed similar performance, where BW30 showed rejections of 95.3% for MCPA and 25.9% for acid, but initial flux of 13 L.m−2.h−1 declined by 82% upon reaching 80% volume recovery. For the novel TSRO using BW30 and swing temperature from 24°C to 45 °C based on MCPA solubility tests, practical higher overall flux was achieved while showing similar MCPA rejection, but with slightly higher acid rejection of 37%. Pilot scale NF using NF270 and NF90 membranes showed decreased rejections of both MCPA and acid. The NF270 showed rejections of 71.3% for MCPA and 16.8% for acid. But despite lower MCPA rejection, its high flux up to 80% volume recovery could be used with RO or other treatments to meet MCPA discharge requirements. RO and NF are therefore suitable for MCPA removal from saline (HCl-rich) wastewaters, but novel temperature swing RO process offers potential to achieve higher MCPA rejection simultaneously to higher overall flux at practical volume recoveries.

The Impact of Operational Conditions on Commercial Membranes using in Removing Nitrate from Drinking Water

It is a great advantage to reduce the energy requirement for the provision of consumable groundwater to an absolute minimum. Reverse osmosis (RO) and nanofiltration (NF) are two of the most commonly used technologies for desalination water to provide potable water with lowest energy consumption. However, there is still lack of a thorough comparison between these two methods providing the better option in different conditions. Therefore, in this paper, nitrate rejection and the effects of operation conditions on the performance of RO and NF systems are compared. Several wells in Zarch District, Iran, are polluted by nitrate and groundwater is a major drinking water source in the region. The aim of this research was to evaluate the efficiency of nitrate removal by two commercial membranes NF90 and BW30 (both Dow Filmtec) using natural water under different operating conditions. Experiments were conducted to assess the influence of temperature and pressure on nitrate removal by the membranes. The results indicated that BW30 (reverse osmosis) performs better removing nitrate than NF90 (Nano-filter). With a feed of 200 mg-NO3-.L-1 (as nitrate), only permeate from the BW30 membrane met the required quality standard for drinking purposes (50 mg-NO3-.L-1). When the feed concentration increased to 250 mg-NO3-.L-1, both membranes failed to achieve the standard in the permeate. The membranes showed similar nitrate removal behaviour under different applied temperatures and pressures. It was concluded that the BW30 membrane can be used to produce drinking water in the study area with influent concentrations below 200 mg-NO3.L-1.

Seawater Desalination by Using Nanofiltration (NF) and Brackish Water Reverse Osmosis (BWRO) Membranes in Sequential Mode of Operation

In this study, the applicability of nanofiltration (NF) membranes as a pretreatment prior to reverse osmosis (RO) in seawater desalination was investigated. The membranes used wereNF270 and NF90 as the NF membranes, while the brackish water (BW) RO membrane BW30 was used as the RO membrane. In desalination tests, permeates of the NF membraneswere collected and used as the feed to the BW30 membrane. The calculated permeate fluxes were 6.7 L/h.m2, 11.3 L/h.m2, 24.3 L/h.m2, and 36.6 L/h.m2 for single BW30-35 bar,NF270-30 bar + BW30-35 bar, NF90-30 bar + BW30-25 bar and NF90-30 BW30-35 bar, respectively. The calculated water recovery and rejected salt values were 51.6%, 41.4%,24.8%, 15.4% and 98.2%, 98.2%, 96.0%, 91.0% for NF90-30 bar + BW30-35 bar, NF90-30 bar + BW30-25 bar, NF270-30 bar + BW30-35 bar and single BW30-35 bar, respectively.The qualities of the product waters of integrated systems (NF+BWRO) and the single BWRO system were also investigated. Boron rejection was fairly well with average boronrejections of 59.3% and 60.2% by NF90-30 bar + BW30-25 bar and NF90-30 bar + BW30-35 bar combinations, respectively while single BW30-35 bar gave an average rejection of49.6%. The results obtained showed that the quality of product water obtained using single BWRO did not comply with the irrigation standards, while the integrated systems providedtotal compliance to irrigation standards with the exception of boron.

Renewable energy powered membrane technology: Impact of solar irradiance fluctuation on direct osmotic backwash

Direct osmotic backwash (OB) during solar energy fluctuations is an important observation in directly coupled, battery-less solar energy powered nanofiltration/reverse osmosis (NF/RO) membrane systems. OB occurs spontaneously and has the potential to induce membrane self-cleaning. The impact of controlled solar irradiance fluctuation conditions, feed water salinity (1–10 g/L) and membrane type (NF membrane NF270, RO membrane BW30) on OB were investigated by periodic step-response tests. The objective of this research was to investigate the OB mechanism under solar irradiance fluctuations. The results show that solar energy fluctuations lead to a change of filtration hydrodynamic conditions (feed flow rate, applied pressure), operating time, and permissible backwash time. This results in variations of OB driving force which is determined by the osmotic pressure difference during filtration. High feed water salinity and solar irradiance before fluctuation enhance the OB process, while relative high solar irradiance during fluctuation weakens the OB process. Furthermore, the BW30 membrane shows a higher OB flow rate and less accumulated volume than NF270. This was attributed to the higher salt retention of BW30 resulting in a larger backwash driving force and much lower flux of BW30 which in turn caused a thinner CP layer. These findings indicate that solar irradiance fluctuation conditions may potentially delay fouling and hence enhance the reliability and robustness of battery-less photovoltaic-membrane systems.

Potential of nanofiltration and reverse osmosis processes for the recovery of high‐concentrated furfural streams

AbstractBACKGROUNDFurfural is an interesting compound that can be produced from renewable and sustainable resources and is used in platform chemicals for the synthesis of biofuels and other chemicals. However, a recovery step is required to separate furfural from lignocellulosic hydrolysates when cellulose‐based raw materials are used. In this work, nanofiltration (NF) and reverse osmosis (RO) processes have been evaluated to purify or concentrate synthetic furfural solutions.RESULTSTwo NF membranes (NF90 and NF270) and three RO membranes (XLE, BW30 and SW30) were evaluated to recover furfural from high‐concentrated solutions containing 9 g furfural L−1. Rejection percentages and permeate flux performances were determined and membranes were characterized by X‐ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Results indicated that higher trans‐membrane flux could be obtained by NF membranes, being the highest when using NF membranes (260 ± 14 L m−2 h−1) and the lowest with the BW30 membrane (3.3 ± 0.7 L m−2 h−1) working at 20 bar. On the other hand, NF270 allowed the passage of furfural (around 84 ± 3%), while the other tested membranes (NF90, XLE, SW30 and BW30) rejected it (between 67 ± 2 and 90 ± 3%).CONCLUSIONFor this reason, it can be concluded that NF270 will be an option for furfural purification, while NF90 and RO membranes could be used for concentration purposes. © 2019 Society of Chemical Industry

Valorization of olive pomace by a green integrated approach applying sustainable extraction and membrane-assisted concentration

Olive pomace is a semi-solid paste resulting from the two-phase olive oil production, being the most significant waste generated by this agro-industry. Olive pomace is reported as an environmental hazard due to its high content in phenolic compounds (phytotoxic). Nevertheless, these compounds, when recovered, can have impactful actions in different human physiological conditions, namely, skin protection, dysfunction treatment or diseases prevention. Therefore, their recovery from olive pomace is crucial for environmental and economical sustainability, without forgetting the functional challenge.In a previous work, lipid and aqueous fractions of olive pomace were studied regarding its major bioactive compounds. The present research aims to describe an environmentally friendly integrated approach to extract and concentrate (by a pressure-driven membrane processing) the phytotoxic compounds of olive pomace.Three types of polymeric composite membranes (NF90, NF270 and BW30) were tested. The composition of the resulting streams (permeates and concentrates) were compared and the process efficiency assessed based on: (1) antioxidant activity and total phenolic and flavonoid contents; (2) inorganic elemental composition (by Inductively Coupled Plasma Atomic Emission Spectroscopy); (3) pH, conductivity and total organic carbon; and (4) permeate flux, membranes' apparent target solutes rejection and fouling index.The BW30 membrane presented the lowest fouling index and was the most effective for extracts concentration, with no phenolic compounds in the permeates, preventing completely the loss of such compounds.

Assessing potential of nanofiltration and reverse osmosis for removal of toxic pharmaceuticals from water

Concern about organic micropollutants, which are present in the environment at trace concentrations (ng L−1–μg L−1) is related to the adverse effects to organisms exposed to these substances. Pharmaceutically Active Compounds (PhCAs) may be present in natural waters and usually cannot be removed or degraded by conventional water treatment processes. For this reason, treatment techniques, such as Nanofiltration (NF) and Reverse Osmosis (RO) are recommended to improve their removal. In this context, the present study aims to evaluate the removal of five Non-steroidal anti-inflammatory drugs (NSAIDs), analgesics and anti-pyretic: acetaminophen, ibuprofen, dipyrone, diclofenac, and caffeine by NF and RO process. NF90 and BW30 membranes were characterized by scanning electron microscopic (SEM), contact angle and zeta potential. Retention of PhACs was evaluated considering pH feed solution and operating pressure. Results indicated that NF90 membrane was efficient to reach over 88% rejection for some selected PhACs. Best results were obtained at 20 bar and pH 5 with more than 90% of rejection. For nonionic compounds acetaminophen and caffeine, exclusion by size is the main mechanism for rejection by NF90 membrane, whereas for anionic compounds ibuprofen, dipyrone, and diclofenac, electrical exclusion predominated at pH 5 and 7. Rejection results with NF90 membrane show that hydrophobicity has an important role due to the adsorption on the membrane surface. Conversely, lower rejections for hydrophilic compounds were observed due to the adsorption/diffusion mechanisms, both in NF90 and RO at pH 5.

Integration of MBR with NF/RO processes for industrial wastewater reclamation and water reuse-effect of membrane type on product water quality

In this study, some field tests were conducted at ITOB Organized Industrial Zone Wastewater Treatment Plant where membrane bioreactor (MBR) process has been used for wastewater treatment. The MBR treatment process provides stable and high quality product water but product water still contains high salinity in this case. Therefore, a mini-pilot scale membrane test system having three different nanofiltration (NF) which are NF90, NF270 and TR60 and two different reverse osmosis (RO) membranes which are BW30 and AG with spiral wound configurations was employed for demineralization of MBR effluent. The system was operated with 10 bar of operating pressure for NF membranes and at 20 bar for RO membranes. The average water recoveries of NF membranes were 50.2%, 56.0% and 51.8% for NF90, NF270 and TR60 membranes, respectively while average water recoveries of RO membranes were 64.0% for BW30 membrane and 62.3% for AG membrane. The qualities of product waters were analyzed and compared with standards to reuse them for agricultural irrigation and as process water. The permeates of NF270 and TR60 membranes agreed well with the third class water quality for salinity and the second class quality for the rest of parameters. On the other hand, the permeates of NF90, BW30 and AG membranes provided with the first class water for all parameters except for infiltration. Mixing the permeates of NF and RO membranes with MBR effluent in appropriate ratios was considered to be helpful to get acceptable quality values for product water and a good permeability for agricultural irrigation. Therefore, an optimum theoretical mixture of MBR effluent to permeates was determined. When qualities of product water obtained by NF and RO membranes were compared with the standards of cooling and boiling feedwaters for industrial usage and with the process water characteristics for pulp and paper, textile industries, it was considered that the permeates of NF90, BW30 and AG membranes obeyed well the quality standards required.

Real-scale chlorination at pH4 of BW30 TFC membranes and their physicochemical characterization

Chlorination remains a big hurdle in membrane technology as the most commonly used membranes for water purification consist of a polyamide top-layer, which is not fully resistant towards chlorine-induced oxidation. In this work, DOW FILMTEC™ BW30 membrane elements were systematically chlorinated with NaOCl at pilot-scale under acidic conditions (pH4) at 10bar for 2.5h. Variations in membrane performance and their physicochemical properties were determined by ATR-FTIR, XPS, WD-XRF, SEM, AFM and zeta-potential measurements. With increasing bleaching concentration, both membrane roughness and chlorine incorporation via N- and ring-chlorination increased, while surface charge remained quasi unaltered. Both water flux and salt passage decreased proportionally over the whole concentration range. Accordingly, positron annihilation lifetime spectroscopy (PALS) revealed a decrease in the size of the top-layer free-volume elements as chlorine concentration increased, confirming, for the first time in a quantitative manner, the so-called tightening effect. The obtained results also show that thin-film composite (TFC) membranes are altered differently when chlorinated under pressure than via simple immersion, as conventionally performed in literature.