Filtration Efficiency Of Membranes Research Articles

Modified PVDF/PMMA/SiO2 composite nanofibrous membrane in airborne filtration: Transparency, mechanical properties and filtration performance

A comprehensive study on four modified Polyvinylidene Fluoride (PVDF) nanofibrous membrane was conducted to fabricate transparent air filters for the first time when adding Polymethyl methacrylate (PMMA) and SiO2. The modified PVDF nanofibrous membrane properties were extensively characterized using scanning electron microscopy, infrared analysis, crystallinity, and investigated the optical transparency, mechanical properties, and filtration performance. The enhancement of PMMA is greater than the weaken of SiO2 with the PVDF/PMMA/SiO2 membrane average transparency of 70.48 %. The PVDF membrane mechanical strength enhanced by SiO2 and weakened by PMMA is visualized by a Weibull two-parameter distribution model. The PVDF/PMMA/SiO2 membrane filtration efficiency is 94.12–96.39 %, and the impressive quality factor (Qf) of 0.074 Pa⁻1 is superior to other three modified membranes in filtration performance while maintaining the sufficient ultimate tensile strength (UTS) of 20.41±0.28 MPa.

Enhanced performance of aerobic granular sludge-membrane system through the utilization of different iron-based nano-metal oxides for mitigating membrane fouling

Fe3O4, γ-Fe2O3, and α-Fe2O3 nanoparticles play a crucial role in influencing the adsorption capacity and pretreatment efficacy as iron-based nano-metal oxides due to their distinct structural and physicochemical properties. However, the impact of these adsorbents on membrane filtration efficiency remains unexplored. This study aimed to investigate the influence of these three adsorbents on membrane fouling in an aerobic granular sludge–membrane system (AGSMS) used for municipal wastewater reuse treatment. The results demonstrated that under optimal conditions, γ-Fe2O3 exhibited superior effectiveness in removing low and medium molecular weight contaminants from wastewater, resulting in a higher normalized flux (0.59) and reduced total fouling resistance (2.66 × 1011 m−1). It also showed the highest removal rate for organic matter and suspended solids, making it particularly effective in mitigating AGSMS membrane fouling. However, excessive addition (2 g/L) of Fe3O4, γ-Fe2O3, and α-Fe2O3 could potentially hinder the proper operation of the AGSMS. Pre-adsorption facilitated the formation of a porous cake layer while inhibiting standard blocking behavior. Additionally, the extended Derjaguin–Landau–Verwey–Overbeek theory analysis revealed a substantial energy barrier between membrane-foulant interactions (125.65 kT) as well as foulant-foulant interactions (62.06 kT) within the γ-Fe2O3 system, confirming its exceptional antifouling characteristics. This study offers valuable insights into the selection of iron oxide adsorbents for membrane fouling mitigation and wastewater reuse.

Effect of micro and nanobubble size and concentration on membrane fouling: Strategies for energy-saving and ultrafiltration efficiency enhancement

The impact of micro and nanobubbles (MNBs) on preventing membrane fouling in various filtration techniques has been effectively demonstrated. However, there remains a gap in understanding the influence of their size and concentration on membrane fouling. Moreover, the substantial energy demand for MNBs-aided filtration processes hinders the wide adoption of this technology on a global scale. This study controlled MNB size and concentration by optimizing the release pressure of air-saturated water and introducing intermittent operation schemes. At 0.35 MPa, the MNBs averaged 91 μm and 117.9 nm with concentrations of 3.27E+3 and 6.85E+6 particles mL−1. Increasing the pressure to 0.60 MPa reduced the average size to 31 μm and 119.9 nm. Concentrations to 6.43E+5 and 9.40E+6 particles mL−1. Bubbles released at 0.60 MPa reduced TMP from −0.0109 MPa attained with 0.35 MPa bubbles to −0.0052 MPa making a 70 % decrease. Comparing continuous and optimal intermittent release patterns (30 min) revealed marginal differences: normalized transmembrane pressure (4 %), cleaning efficiency (9 %), and rejection efficiency (2.4 %). Our approach enhances membrane filtration efficiency, maintains performance, reduces energy consumption, and advances sustainable filtration technologies encouraging global adoption.

Developing Innovative Nanomaterials as Adsorbents for Water Treatment and their Environmental Impact

Water treatment is paramount in tackling the increasingly pressing environmental issues associated with water contamination. The present study investigates the progression of novel nanomaterials as exceptionally effective adsorbents for water purification while also evaluating their potential ecological consequences. The significance of water treatment cannot be overstated when it comes to protecting the environment and ensuring public health. This is due to the intricate and varied pollutants that are brought into water sources from many sources of waste, such as household, industrial, and environmental concerns. Adsorbents are crucial in capturing and immobilizing contaminants, making them essential instruments in this particular setting. Nanomaterials have garnered attention as potential adsorbents owing to their notable specific surface area and adjustable features. These materials possess a large surface area, reactivity, and configurable surface chemistry, rendering them intriguing candidates for adsorption applications. This manuscript presents the Innovative Nanoparticles for Water Treatment Framework (INM-WTF). This innovative approach utilizes state-of-the-art nanoparticles to improve water treatment processes' efficiency significantly. The outcomes of the INM-WTF experiment include the following parameters: Pollutant Removal Efficiency of 96.5%, Permeate Flux of 395 L/m²h, Adsorption Capacity of 155 mg/g, Photocatalytic Degradation Rate of 85%/hour, Membrane Filtration Efficiency of 97.5%, and Water Quality Compliance of 1.7 µg/L. The results indicate significant progress in water treatment capabilities, emphasizing nanomaterials' potential to tackle environmental issues, enhance water quality, and guarantee adherence to rigorous regulatory benchmarks.

Adsorptive dynamic membrane for water purification: Model and optimization

Adsorptive dynamic membrane, consisting of adsorption and filtration, exhibits a desirable efficiency for water purification. However, the entire adsorption-filtration process is affected by many influencing factors, and the operating regulation and process optimization remain still uncertain. The present work deals with the process optimization for adsorptive dynamic membrane treating micro-polluted water. A Box-Behnken response surface methodology was utilized to investigate the effect of operating conditions (dye concentration, agitation speed, carbon nanotubes dosage, Transmembrane Pressure and pH) on the dye removal and flux. The response surface methodology with high coefficients of determination values were fitted to the experimental data, which demonstrated that the polynomial response models fitted well for describing dye removal and adsorptive dynamic membrane filtration efficiency. Based on the design, the optimized conditions for obtaining highest dye removal rate (100%) were dye concentration = 5 mg/L, agitation speed = 210 rpm, carbon nanotubes dosage = 13 g/m2, Transmembrane Pressure = 0.2 mPa and pH = 5.8. The graphical optimization of superimposed contour plots fulfilled the conditions to obtain dye removal >95% and flux >100 L m−2 h−1, as well the interactions among various operating conditions. The work indicated that response surface methodology can be applied for analyzing the effect of operating conditions and acquiring the optimized conditions for adsorptive dynamic membrane treating water/wastewater.

Preparation and Characterization of Microporous Cellulose Membranes as Potential Pathogen Filters

Growth and development in the textile and fashion industry have resulted in the generation of large amounts of industrial pre-consumer textile wastes. It is estimated that 10 to 20% of textile fabrics are wasted during garment manufacturing, with most of the wastes being burned or landfilled. Reusing pre-consumer fabric wastes is therefore considered a viable approach to alleviate environmental impacts associated with their disposal. To achieve a higher porosity membrane, pre-consumer cotton fabrics were partially dissolved in a solution of dimethyl acetamide (DMAc) and lithium chloride (LiCl), and the resulting fibre suspension was utilized to prepare a microporous cellulose membrane (MCM) through a vacuum filtration method. The suspension comprised a mixture of partially and completely dissolved fibres, which provided the required morphological and structural integrity to the fibrous membranes. The membranes’ chemical structure, fibre size, and morphology were characterized based on Fourier transform infrared spectroscopy (FT-IR), light microscope, and field emission scanning electron microscopy (FE-SEM), respectively. The filtration efficiency of the microporous cellulose membranes was evaluated against 500 ppm sodium chloride (NaCl) solutions. The results showed that the filtration efficiency of the membranes ranged between 31.82 and 59.85% for cellulose membranes with 60.2% porosity, suggesting that the membranes could be applied as filters against pathogens upon further improvement.

Microalgae enrichment for biomass harvesting and water reuse by ceramic microfiltration membranes

Harvesting and water reuse are two critical issues for large-scale microalgae cultivation. Using two representative microalgae species, namely C. vulgaris and Scenedesmus sp., this study evaluates the performance of a ceramic microfiltration membrane to extract clean water for reuse and pre-concentrate the microalgae solution for subsequent harvesting. The results show that fouling was specific to each individual microalgae species due to the difference in cell properties (e.g. size, shape, and cell membrane). Importantly, membrane fouling could be efficiently mitigated by aeration and regular backwashing without any chemical addition. Aeration reduced the transmembrane pressure when filtering C. vulgaris and Scenedesmus sp. by 56 and 38%, respectively. In long-term performance experiments, C. vulgaris showed considerable membrane fouling over time; by contrast, Scenedesmus sp. showed negligible fouling. The results reaffirmed that membrane filtration efficiency was microalgae species-specific. Permeate water reuse for growing another batch of microalgae was also demonstrated using both species. Results reported here suggest that ceramic microfiltration membrane can simultaneously enrich the microalgae solution and recycle permeated water for microalgae cultivation.

UV and bacteriophages as a chemical-free approach for cleaning membranes from anaerobic bioreactors

Anaerobic membrane bioreactor (AnMBR) for wastewater treatment has attracted much interest due to its efficacy in providing high-quality effluent with minimal energy costs. However, membrane biofouling represents the main bottleneck for AnMBR because it diminishes flux and necessitates frequent replacement of membranes. In this study, we assessed the feasibility of combining bacteriophages and UV-C irradiation to provide a chemical-free approach to remove biofoulants on the membrane. The combination of bacteriophage and UV-C resulted in better log cells removal and ca. 2× higher extracellular polymeric substance (EPS) concentration reduction in mature biofoulants compared to either UV-C or bacteriophage alone. The cleaning mechanism behind this combined approach is by 1) reducing the relative abundance of Acinetobacter spp. and selected bacteria (e.g., Paludibacter, Pseudomonas, Cloacibacterium, and gram-positive Firmicutes) associated with the membrane biofilm and 2) forming cavities in the biofilm to maintain water flux through the membrane. When the combined treatment was further compared with the common chemical cleaning procedure, a similar reduction on the cell numbers was observed (1.4 log). However, the combined treatment was less effective in removing EPS compared with chemical cleaning. These results suggest that the combination of UV-C and bacteriophage have an additive effect in biofouling reduction, representing a potential chemical-free method to remove reversible biofoulants on membrane fitted to an AnMBR.

Impact of a Graphene Oxide Reducing Agent on a Semi-Permeable Graphene/Reduced Graphene Oxide Forward Osmosis Membrane Filtration Efficiency.

Graphene has been considered as a material that may overcome the limitations of polymer semi-permeable membranes in water treatment technology. However, monolayer graphene still suffers from defects that cause leakage. Here, we report a method of sealing defects in graphene transferred onto porous polymer substrate via reduced graphene oxide (rGO). The influence of various reducing agents (e.g., vitamin C, hydrazine) on the properties of rGO was investigated by SEM, Raman, FTIR, and XRD. Subsequently, membranes based on graphene/reduced graphene oxide were tested in a forward osmosis system using sodium chloride (NaCl). The effect of the effectiveness of the reduction of graphene oxide, the type and number of attached groups, the change in the distance between the rGO flakes, and the structure of this material were examined in terms of filtration efficiency. As a result, semi-permeable centimetre-scale membranes with ion blocking efficiency of up to 90% and water flux of 20 mL h−1 m−2 bar−1 were proposed.

Functionalization of reverse osmosis membrane with titania nanotube and polyacrylic acid for enhanced antiscaling properties

Membrane surface scaling is a major challenge in reverse osmosis (RO) desalination process that could irreversibly deteriorate the membrane filtration efficiency. In this study, a hydrophilic coating layer was introduced onto the polyamide (PA) layer of self-developed thin film nanocomposite (TFN) membrane via plasma enhanced chemical vapour deposition (PECVD) technique to increase the membrane surface energy barrier and hydrophilicity towards silica heterogeneous nucleation. The results revealed that the acrylic acid-coated TFN membrane (AA-TFN) exhibited excellent resistance against silica scaling after subjected to saturated silica concentration (168 ppm at pH 6.7), with much higher flux recovery rate (FRR) (88%) compared to the uncoated TFN (75.5%) and conventional thin film composite (TFC) (72%) membranes. This is attributed to its enhanced surface hydrophilicity (contact angle of 26°) and better surface charge (zeta potential of −47 mV at pH 6.7) upon the hydrophilic coating layer deposition which retards the scale deposition. The membrane scaling can be further reduced by increasing the feed pH and at the optimized condition (pH 10), the FRR of AA-TFN membrane could reach up to 98.3%, owing to the increased silica solubility at alkaline condition which minimizes the silica aggregation formation on the membrane surface. Our work demonstrated that surface modification of composite membrane using suitable materials and proper feed pH adjustment could offer a great promise in mitigating the scaling for desalination applications. The findings also provide fundamental insights on the importance of membrane surface properties during silica scaling formation.

Application of modified cellulose-based antiscalant in reverse osmosis membrane scaling control

<p indent=0mm>Applying membrane scaling is a key problem in reverse osmosis (RO) desalination processes. By dosing antiscalant, we can effectively inhibit inorganic scale and control RO membrane scaling. Accordingly, in this work, an environmentally friendly modified cellulose-based antiscalant is synthesized by the etherification of cellulose and subsequent graft copolymerization using the etherification product carboxymethyl cellulose (CMC), acrylic acid (AA), and sodium allyl sulfonate (SAS): CMC-<italic>g</italic>-P(AA-<italic>co</italic>-SAS). The influence of molecular structure, CMC-<italic>g</italic>-P(AA-<italic>co</italic>-SAS) dose, and coexisting anions with respect to inhibiting the calcium-sulfate scale in the RO system are investigated. The results indicate that dosing CMC-<italic>g</italic>-P(AA-<italic>co</italic>-SAS) can significantly prolong the induction time of calcium-sulfate crystallization, inhibit the formation of calcium-sulfate scale, greatly alleviate both membrane fouling and membrane flux decline caused by membrane-surface scale formation, and effectively improve the membrane filtration efficiency. Static tests, scanning electron microscopy, optical microscopy, X-ray diffraction, conductivity measurements, and dispersion experiments suggest that the scale inhibition mechanism of CMC-<italic>g</italic>-P(AA-<italic>co</italic>-SAS) can be attributed to the chelation and dispersion effects of the introduced anionic groups, and that the carboxyl groups are more efficient in the inhibition of calcium-sulfate scale than the sulfonic groups. In addition, an appropriate number of sulfonic groups on the graft chain of CMC-<italic>g</italic>-P(AA-<italic>co</italic>-SAS) can improve the water solubility of CMC-<italic>g</italic>-P(AA-<italic>co</italic>-SAS), as well as effectively stabilize the scale-formed substances and enhance the scale inhibition efficiency. If the proportion of sulfonic groups is too high, the content of the carboxyl groups decreases accordingly, which reduces the chelation and dispersion effects of CMC-<italic>g</italic>-P(AA-<italic>co</italic>-SAS), which, in turn, reduces the scale inhibition performance.

Indigenously developed CuO/TiO2 coated ceramic ultrafiltration membrane for removal of emerging contaminants like phthalates and parabens: Toxicity evaluation in PA-1 cell line

Emerging contaminants like phthalates and parabens in pharmaceuticals and personal care products pose threat to humans and environment because they are endocrine disruptors and are persistent in nature. Removal of these contaminants by conventional treatment methods has proven less effective in removing emerging contaminants. Ceramic ultrafiltration (UF) membrane developed indigenously from CuO/TiO2 nanoparticles effectively removed phthalates and parabens from synthetic systems (10–1000 ppb concentration) with removal efficiency of >99%. FTIR (Fourier Transform Infrared Spectroscopy) analysis suggested surface adsorption of phthalate and paraben on UF membrane. The effect of different parameters, viz. Transmembrane pressure (TMP), time, feed concentration on membrane filtration efficiency, was calculated by response surface methodology (RSM). Cytotoxic effects of untreated and membrane treated phthalate and paraben solutions were observed on ovarian teratocarcinoma (PA-1) cell lines. Cytotoxicity was evaluated by cell toxicity and reactive oxygen species (ROS) generation in culture PA-1 cells. Results showed that concentration IC50 (half maximal inhibitory concentration) values for phthalate untreated and treated samples were 54.9 μg/ml and 183.23 μg/ml respectively while for paraben untreated and treated samples were 16.8 μg/ml and 107.6 μg/ml respectively.

Preparation of a novel poly (ether ether ketone) nonwoven filter and its application in harsh conditions for dust removal

It has been proved that air filtration is the most effective solution to solve air pollution from the origin. However, as the core filter material in air filter bags, most of fiber materials are not able to maintain their basic performance under the condition of high temperature, high humidity and corrosion. Hence, creating such a new material used in harsh conditions for dust removal has proved to be extremely challenging. In this study, high-performance poly (ether ether ketone) (PEEK) fiber was developed to fabricate a PEEK nonwoven filter (PEEK NWF) which showed outstanding stability under sulfuric acid, sodium hydroxide and 250 °C high temperature conditions. Moreover, to capture more fine particles, PEEK NWF impregnated with PTFE emulsion (PEEK/PTFE) and ePTFE coated membrane PEEK (PEEK/ePTFE) filter with a sandwich structure were also constructed. PEEK NWF and PEEK/PTFE filters exhibited extremely low filtration resistance (10 Pa, 10.3 Pa) and higher quality factor (0.7036 Pa−1, 0.8222 Pa−1). Compared with PEEK NWF and PEEK/PTFE filters, PEEK/ePTFE filter displayed higher filtration efficiency for fine particles, and its filtration efficiency for particles size of 2.5 μm increased from 72.09% to 98.5765% which was close to nanofiber membrane filtration efficiency. The results suggested that PEEK NWF as well as its composites filters could make them promising candidate materials used in harsh conditions for dust removal.

Removal of manganese, ferrous and antibiotics from groundwater simultaneously using peroxymonosulfate-assisted in-situ oxidation/coagulation integrated with ceramic membrane process

The simultaneous occurrence of iron, manganese and antibiotics within groundwater enhances the difficulties for drinking water treatment. In this study, the peroxymonosulfate (PMS)-assisted in-situ oxidation/coagulation(O/C) coupled with ceramic membrane process was employed to remove the iron (Fe2+: 2.0–4.2 mg/L), manganese (Mn2+: 0.99–4.12 mg/L), and antibiotics (Sulfamethazine(SMZ) = 400–800 µg/L) simultaneously. The results indicated that Fe2+ existing in groundwater was able to in-situ active PMS for producting hydroxyl radicals (OH) and sulfate radicals (SO4−), oxidizing antibiotics or natural organic matter (NOM) together with manganese and ferrous. Subsequently, through scanning electron microscopy (SEM), X-ray energy-dispersive spectroscopy (EDS) and laser scattering particle analyzer (LSPA), it was found that the aggregates (264–685 µm) generated by oxidation/coagulation process were effectively rejected by ceramic ultrafiltration membrane. Besides, membrane filtration performance depended strongly on the crystallization structure of aggregates. The X-Ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis demonstrated that NOM in groundwater weakened the crystallization of ferric hydroxides or manganese precipitation, diminishing membrane filtration efficiency. Based on the outstanding performance of in-situ O/C, this integrated process exhibits considerable potential application in the treatment of groundwater, and the highlight was that ferrous within groundwater could be utilized to active PMS in-situ.

Graphene Oxide Membranes for Isotopic Water Mixture Filtration: Preparation, Physicochemical Characterization, and Performance Assessment

There is an increasing demand for nuclear reactors, driven by the global need for low CO2 producing energy sources. The use of light (H2O) or heavy water (D2O) in a nuclear reactor environment produces radioactive tritiated heavy (HTO, DTO) water as an inevitable contaminant. Considering the need for tritiated water removal and also the high commercial value of purified water isotopes, technologies that can efficiently separate isotopic mixtures of water in nuclear reactors are highly desirable. This study presents an experimental approach for producing graphene oxide (GO) membranes and assessing their performance in the filtration of isotopic water mixtures. Specifically, using D2O/H2O mixtures as model systems, we investigate the effect of physicochemical properties of GO, as well as membrane preparation conditions on membrane filtration efficiency. We find that membranes assembled using larger GO platelets of lower oxidation level generally exhibit higher deuterated water (HDO, D2O) rejection and filtrate flux. Moreover, membrane preparation conditions have a strong impact on the interlayer space between stacked GO nanoplatelets in the membrane, hence as a direct effect on filtration performance. Our experimental results also show a strong, nonmonotonic dependence of separation performance on operating temperature, as well as the existence of local temperature optima. Our work provides guidelines for simple and scalable preparation of GO membranes with very good mechanical stability, capable of achieving efficient separation of isotopic water.

Application of green synthesized ZnO nanoparticle coated ceramic ultrafiltration membrane for remediation of pharmaceutical components from synthetic water: Reusability assay of treated water on seed germination

Discharges from pharmaceutical sectors into water bodies are major environmental issue as most of them are persistent in nature and causes endocrine disruption. Treatment processes presently undertaken are not effective in complete removal of these contaminants. Removal study of ibuprofen has been undertaken by adsorption and nanofiltration membrane whereas little knowledge of atenolol separation by membrane has been reported. Ceramic ultrafiltration membrane developed from green synthesized zinc oxide nanoparticles (ZnO NPs) was employed in this present study for removal of atenolol and ibuprofen drugs from synthetic solution. About 96 % and 99 % removal of atenolol and ibuprofen respectively was obtained by single step ultrafiltration process. UF membrane developed had surface area of 21.503 m2/g and pore diameter of 39.8 Å. X-ray diffraction study of unsupported membrane showed pure phase crystalline zinc oxide particles. The effect of different parameters viz., TMP (Transmembrane pressure), time, feed concentration etc. on membrane filtration efficiency was analyzed by RSM (Response Surface Methodology). Germination studies on Vigna mungo was performed using untreated atenolol and ibuprofen solutions and membrane treated permeate to assess the membrane efficiency of producing clean water suitable for reuse. The study revealed higher germination rate in presence of ibuprofen solution but lower germination for atenolol solution. Protein content on the other hand were highly affected in both ibuprofen and atenolol solution. Seeds germinated in membrane permeate showed better germination rate and protein content and comparable to that of control.

The synthesis of nanofiber membranes from acrylonitrile butadiene styrene (ABS) waste using electrospinning for use as air filtration media.

Acrylonitrile butadiene styrene (ABS) waste has been successfully recycled into nanofiber membranes by an electrospinning method for air filter applications. The ABS precursor solutions were made by dissolving the ABS waste in three different solvents, DMAc, DMF, and THF, with various concentrations of 10, 20, and 30 wt%. The solvent and solution concentrations affected the fiber properties (size and morphology) and membrane properties (wettability, crystallinity, and mechanical). Accordingly, we tested the fabricated membranes using SEM, FTIR, XRD, water contact angle, and tensile strength test measurements. The SEM images depicted three different morphologies, i.e. beads, beaded fibers, and pure fibers. The FTIR spectra showed that the solvents completely evaporated during the electrospinning process. The water contact angle test exhibited the hydrophobic properties of all the membrane samples. The XRD spectra showed the amorphous structures of all the membranes. The tensile strength test showed that the membranes fabricated using DMF and DMAc solvents had the best mechanical properties. Considering the fiber size, wettability, and mechanical properties, the membranes fabricated using DMAc and DMF solvents had the best criteria as air filter media. Filtration tests on the membranes fabricated using DMAc and DMF solvents with various solution concentrations depicted that the beads affected the membrane pressure drop and efficiency. The beads gave more space among the fibers, which facilitated the air flow through the membrane. The beads greatly reduced the pressure drop without an overly reduced membrane filtration efficiency. This led to a high-quality factor of the membranes that demonstrated their applicability as potential air filter media.

Recovery of NH3-N from mature leachate via negative pressure steam-stripping pretreatment and its benefits on MBR systems: A pilot scale study

Given the high ammonia nitrogen (NH3-N) concentration and low biological oxygen demand/chemical oxygen demand (BOD/COD) ratio (<0.1) in mature landfill leachate, it is hard to treat it with the membrane bioreactor (MBR) system to meet the discharge standard for Pollution Control of the Municipal Solid Waste Landfills” (GB16889-2008) without additional carbon source. This pilot-scale study evaluated the use of negative pressure steam-stripping technology for the pretreatment of mature landfill leachate. Our study results have shown that NH3-N concentrations of raw leachate and treated effluent from steam-stripping tower were respectively 2941–3648 mg/L and 401–710 mg/L, yielding an average NH3-N removal efficiency of 82.03%. Nitrogen (N) was recovered via the formation of NH4HCO3 in the ammonia recovery tower, and the effluent of steam-stripping tower was further treated by MBR system. Economic evaluation results showed that initial investment in pretreatment could be offset by respectively reducing energy consumption and operational costs of the MBR system by 60% and 80%. Furthermore, most of Ca2+ and Mg2+ in mature leachate was removed through the formation of CaCO3 and MgCO3 after pretreatment, which avoided membrane fouling and increased the membrane filtration efficiency of MBR system. To conclude, this pilot-study has indicated that negative pressure steam-stripping pretreatment is an efficient and cost-effective technology for the removal of NH3-N, making MBR technology viable without the need for additional carbon source.

Aqua Membranes, Henkel to promote printed membrane spacer technology

Aqua Membranes, an Albuquerque, New Mexico-based developer of dimensional spacer technologies for improved membrane filtration efficiency, has finalized a commercial agreement with Henkel Adhesive Technologies to utilize each other's expertise and knowledge base to develop new innovations in membrane technology.

The ultrafiltration efficiency and mechanism of transglutaminase enzymatic membrane reactor (EMR) for protein recovery from cheese whey

Transglutaminase was immobilised onto a polyethersulfone membrane surface and the resulting enzymatic membrane filtration efficiency and mechanism for the catalysis of protein cross-linking and separation from cheese whey was investigated. Transglutaminase was confirmed to be covalently immobilised onto the polyethersulfone membrane surface by Fourier transform infra-red and X-ray photoelectron spectroscopy. The protein recovery rate reached 85% in the transglutaminase enzymatic membrane reactor (EMR). The observed decrease of the protein recovery rate and relative membrane flux over time were mainly due to the decrease in enzymatic activity on the membrane surface after 1365 min of continuous operation. The total membrane resistance of the EMR was approximately 50% less than that of pure polyethersulfone membrane whey filtration. The main cause of the decreased resistance was that repulsive force energy was observed between cross-linking proteins and enzymatic membrane, which was identified through analysis based on the extended Derjaguine-Landaue-Verweye-Overbeek (XDLVO) theory.