Filtration Flux Research Articles

Flux and fouling behavior during constant pressure sterile filtration of nanoemulsions

Nanoemulsions with droplet diameters from 20 to 200 nm have emerged as attractive adjuvants in the development of novel vaccines and as an advanced method of drug delivery for hydrophobic drugs. However, the large size of the nanoemulsion droplets leads to very low capacities during the final sterile filtration step used to ensure sterility of parenteral drug products. The objective of this study was to examine the sterile filtration of a model nanoemulsion made using squalene as the oil and Tween 20 and Span 85 as stabilizing surfactants. Data were obtained with different commercial sterile filters with different morphology and chemistry during constant pressure filtration. In each case, there was essentially no filtration until the transmembrane pressure exceeded a critical value related to the force required to push the deformable nanoemulsion droplets through the membrane pores. The filter capacity increased with increasing pressure, going from 700 g/m2 at 140 kPa to 1300 g/m2 at 280 kPa for a dual layer polyethersulfone sterile filter, with the flux decline well described by the complete pore blockage model. The dual layer asymmetric membranes showed much higher capacities than corresponding single layer filters due to the effectiveness of the upper layer in removing larger nanoemulsion droplets that would otherwise block the pores of the sterile filter. The capacity of the different sterile filters was also well-correlated with the initial filtrate flux, with both of these parameters governed by the pore size distribution and surface chemistry of the filters. These results provide important insights into factors controlling the sterile filtration of highly concentrated nanoemulsions used in the formulation of vaccines and drug products.

Innovative high-performance and energy-positive Co-treatment of organic kitchen waste and domestic wastewater using a fluidized bed ceramic membrane bioreactor

The aim of the study was to efficiently treat organic kitchen waste (FW) and domestic wastewater (DWW) together in an anaerobic fluidized bed bioreactor equipped with a ceramic membrane (AnFCMBR) through a sustainable approach considering energy recovery. The system operated continuously for 519 days at room temperature, and different filtration fluxes (1.7 and 5 L/m2/h), hydraulic retention times (HRTs) (22 h and 7 h), and organic loading rate (OLRs) (0.46, 1.52, 3.42, 6.08 kg/m3.d) were tested. The amount of organic matter in DWW may be insufficient for feasible gas production, but this challenge can be resolved through the addition of food waste. Influent chemical oxygen demand (COD) of 500 ± 143 mg/L gradually increased to 2000 ± 196 mg/L by increasing the portion of FW. The COD removal ranged from 92 to 98% throughout the study, with the membrane and the cake layer contributing 5–8% to the performance. Average supernatant SMP and EPS concentrations increased from 5 ± 1 to 45 ± 5 mg COD/L and from 54 ± 7 to 254 ± 26 mg COD/g VSS, respectively, when the highest amount of FW was added to the synthetic wastewater. This significant increase in SMP and EPS concentrations due to the addition of FW negatively impacted the filtration performance. SRF and CST values also increased with rising OLR, especially with the supplementation of synthetic wastewater with FW.After FW started to be mixed with DWW, the methane production increased approximately 5.5 times. With the use of AnFCMBR for the co-treatment of FW and DWW, it is possible to achieve energy-positive treatment with high-quality effluent that can be reused for various applications, such as irrigation. The methane produced provided 12 times more energy than was needed to operate the bioreactor.This is the first study evaluating the co-treatment of FW and DWW in AnFCMBR under varying operational parameters.

Control ultrafiltration membrane fouling in Chlorella-laden water treatment by integrated heat-activated peroxydisulfate pre-oxidation and coagulation treatment

The membrane fouling induced by algal extracellular organic matter (EOM) remain a bottleneck in restricting ultrafiltration (UF) application during harmful algal-water treatment. In current study, the application of heat-activated peroxydisulfate (PMS) and coagulation (Aluminum chlorohydrate, PACI) on membrane fouling behavior during Chlorella-laden water treatment was investigated. The membrane fouling mechanism was analyzed using the extended Derjaguin-Landau-Verwey-Over-beek (XDLVO) theory. The results revealed that separated heat-activated PMS could enhance the filtration flux of EOM at high PMS does >0.2 mM, whereas the membrane fouling was further alleviated by combined heat-activated PMS (0.2–1.0 mM) and PACI (20 mg/L) treatment, especially at low PMS dose. Combined heat-activated PMS and PACI pretreatment could effectively increase the adhesive repulsion between membrane and foulants and reduce the cohesion free energies between organic foulants than those by separated heat-activated PMS treatment, making the initial filtration flux reduced and the cake layer looser. Moreover, the organic foulants of proteins, polysaccharides, and humic-like organics were removed. Cake formation was the major fouling mechanism when EOM was treated with/without separated heat-activated PMS treatment, whereas the membrane fouling mechanism was changed from cake layer formation to pore blocking after combined heat-activated PMS and PACI treatment. Overall, this research provided a feasible method in membrane fouling control during Chlorella -laden water treatment.

Facile fabrication of superhydrophilic copper foam for rapid and efficient filtration of cationic dyes from water

Rapid and efficient separation of dyes from water is a formidable challenge due to the trade-off between separation selectivity and permeability. Here, a novel superhydrophilic copper foam (CF) enabling the rapid and efficient filtration of cationic dyes from water is reported. The fabrication involves brushing a coating consisting of attapulgite (APT), poly(vinyl alcohol) (PVA), TiO2 and glutaraldehyde (GA) onto copper foam and then heating. The obtained copper foam (CF-PVA/GA@APT/TiO2) is superhydrophilic and negatively charged with dye adsorption capability. The interconnected cage-shaped porous structure endows the foam with long tortuous permeation channels and large pore size. It is able to separate various cationic dyes with a separation efficiency reaching to 99.93 % and a permeation flux up to 1671 ± 189 L m-2h−1 under gravity. Furthermore, the CF-PVA/GA@APT/TiO2 can realize the selective separation and recovery of various cationic dyes from rhodamine B (RhB)-mixed dye solutions. Molecular dynamics-based computational modeling and experimental studies revealed that the interaction energy between the surface of CF-PVA/GA@APT/TiO2 and methylene blue (MB) is much stronger than that of the former and RhB, leading to adsorption of MB in the permeation channel, while RhB gradually migrates through the permeation channel and passes through the channel with water. The tortuous permeation channels of CF-PVA/GA@APT/TiO2 increase the contact area and absorption opportunities for cationic dye molecules on the surface, and its large pore size maintains the filtration flux. These properties provide the as-prepared foam with excellent potential applicability for industrial dye wastewater treatment.

Study in the impact of quaternized graphene oxide (QGO) composition as modifier on the chemical, physical, mechanical, and performance properties of polyvinylidene fluoride (PVDF)-based nanocomposite membrane

Polyvinylidene Fluoride (PVDF) membranes were modified with quaternized graphene oxide (QGO) synthesized from graphene oxide and quaternized ammonium groups. PVDF/QGO membranes were created by blending PVDF and 0.01-0.05 g QGO via phase inversion. FTIR confirmed the successful QGO incorporation. PVDF/QGO membranes exhibited increased mechanical stiffness. Meanwhile, SEM revealed asymmetric morphology with surface and internal pores. AFM showed the membrane with 0.05 g and QGO had the highest surface roughness of 101.2 nm, which increased filtration area and flux. QGO improved hydrophilicity through hydroxyl and quaternary ammonium groups, enhancing water flux up to 1208 Lm?2h?1 for 0.05 g QGO. Cu2+ rejection increased to 75% for 0.05 g QGO membrane due to chelation and adsorption effects. PVDF/QGO membranes displayed bacterial growth inhibition, unlike pristine PVDF. The inhibition zone diameter increased with more QGO, indicating improved antibacterial activity. Overall, this study demonstrated that QGO improved PVDF membranes' hydrophilicity, antibacterial properties, and mechanical strength.

Virus retention during constant-flux virus filtration using the Viresolve® Pro membrane including process disruption effects

The growing interest in process intensification and continuous processing has led to concerns regarding the performance of virus removal filters at low permeate fluxes. This paper presents a quantitative analysis of virus retention by the Viresolve® Pro membrane during constant permeate flux filtration and in response to process disruptions using ΦX-174, a bacteriophage, as a model for a mammalian parvovirus. Virus retention by a single layer of Viresolve® Pro membrane was reduced at lower permeate fluxes due to the greater diffusive mobility of phage, although the expected retention for a commercial device employing two layers of membrane remained above 4-logs. The retention data were well correlated with the ΦX-174 Péclet number for filtrate flux from 5 to 100 L/m2/h. Process disruptions caused an immediate transient increase in phage transmission, although this effect was much less pronounced at low permeate flux. The experimental data for phage retention, both with and without process disruptions, were well-described using an internal polarization model with the fraction of virus remaining mobile within the filter scaling as 1/Pe2. In contrast, the fraction of previously captured virus that were re-mobilized after a process interruption was independent of the flow rate. Model equations were developed for rapid estimation of virus performance behavior with the Viresolve® Pro membrane, facilitating the design and implementation of virus filtration processes operating at constant filtrate flux.

A Global Assessment of Groundwater Recharge Response to Infiltration Variability at Monthly to Decadal Timescales

AbstractPredictions of groundwater fluctuations in space and time are important for sustainable water resource management. Infiltration variability on monthly to decadal timescales leads to fluctuations in the water tables and thus groundwater resources. However, connections between global‐scale climate variability and infiltration patterns and groundwater are often poorly understood because the relationships between groundwater conditions and infiltration tend to be highly nonlinear. In addition, understanding is further hampered because many groundwater records are incomplete and groundwater tables are often anthropogenically influenced, which makes identifying the effects of infiltration variability difficult. Previous studies that have evaluated how infiltration variability controls groundwater are based on a limited number of point measurements. Here, we present a global assessment of how infiltration variability is expected to affect groundwater tables. We use an analytical solution derived from Richards' equation to model water level responses to idealized periodic infiltration variability with periods that range from months to decades, to approximate both the effects of short‐term and long‐term climate variability and thus infiltration patterns. Our global‐scale assessment reveals why infiltration variability would lead to periodicity in groundwater recharge in particular regions. The vadose zone strongly dampens short‐term (seasonal and shorter) variations in infiltration fluxes throughout most of Earth's land surface, while infiltration cycles exceeding 1 year would yield transient recharge, except in more arid regions. Our results may help forecasting long‐term groundwater tables and could support improving groundwater resource management.

Mutual-benefit modification of the coagulant solution and fly ash for enhanced sludge dewatering

Faced with the escalating volume of municipal sludge from wastewater treatment plants, urgent measures are required to enhance the sludge dewatering efficiency. This study introduces an innovative and cost-effective approach for mutual modifications of AlCl3 coagulant solution (AC) and fly ash (FA) powder as additives to significantly enhance sludge dewaterability. Unlike the traditional method that modifies agents alone, our technique achieves dual functionalities via blending FA with AC at room temperature. The modified FA (MFA) exhibits a 60 % increase in specific surface area to 2.176 m2/g and ζ-potential shift from –22.2 to +2.0 mV, meanwhile enhances the metal ions content in the modified AC (MAC) by dissolving 96.5 % of Ca, 70.3 % of Mg, 10.6 % of Fe, and 6.1 % of Al ions from FA. When sludge is treated with 5 % MAC and 10 % MFA, the water content in the filter cake is reduced from 84.9 % originally to 52.9 % through plate-frame pressure filtration (PFPF), a significant improvement over 65.4 % for that with unmodified AC and FA treatment, corresponding to the decreased specific resistance to filtration (SRF) and increased the filtration flux during the draining phase. The notable dewaterability enhancement through AC and FA modification is due to the enhanced flocculation and charge neutralization by the abundant metal ions in MAC, coupled with the MFA-facilitated water adsorption and drainage channel maintenance. This one-step, double-benefit modification not only surpasses traditional methods in dewatering efficiency but also reduces sludge treatment costs by 42.4 %, offering a sustainable solution to the increasing challenges of municipal sludge management.

Rod-shaped cellulose nanocrystal/Cu9S5 antibacterial nanocomposites for microfiltration

The development of high-performance antibacterial agents is crucial for controlling bacterial contamination and water purification, while the easy aggregation of the nanomaterials significantly limits their antibacterial activities. Inspired by the palygorskite nanorods' immobilization effect for nanoparticles and rod-shaped structure and surface-rich groups of cellulose nanocrystals (CNC), we in-situ grew the Cu9S5 nanoparticles on the renewable CNCs of different length/diameter ratios to fabricate cellulose nanocrystal/Cu9S5 (CNC/Cu9S5) antibacterial nanocomposites. The size of Cu9S5 nanoparticles shrank from 44 nm before compounding with CNCs to around 4 nm after in-situ growing on CNCs surface, and the obtained CNC/Cu9S5 nanocomposites with good water dispersibility showed excellent antibacterial properties (CNC-M/Cu9S5: 4.6 log reduction rate of S. aureus) by combining the physical puncture effect of CNC-M and copper ions releasing. Afterward, the antibacterial glass fiber/CNC-M/Cu9S5 microfiltration membrane was constructed by depositing the CNC-M/Cu9S5 on glass fiber microfiltration membrane, which showed high filtration flux, high retention capacity for bacteria and good bactericidal performance (>99.9% sterilization rate for S. aureus), suggesting its great potential for water purification.

Experimental evaluation of bearingless spinfilter topologies

Rotating filter membranes can increase the long term filtrate flux by efficiently and continuously removing the retained particles on a microfiltration membrane. However, the practical implementation of rotating machinery in high purity applications such as biotechnological manufacturing of proteins raises concerns about the contamination of the process fluids due to submerged bearings and imperfect sealings to the outside environment. Bearingless and hermetically sealed spinfilters provide a solution to these drawbacks, but create challenges due to the contactless operation, and consequentially, the open internal gap between the feed and the filtrate. To address this, five bearingless spinfilter topologies to reduce the remixing across the open gap are proposed, experimentally evaluated, and discussed. Three spinfilter topologies reach a filtrate purity of 100%, while the best performing concept reaches specific filtrate fluxes of over 2300Lh−1m−2.

Membrane fouling during the harvesting of microalgae using static microfiltration

A challenge in the filtration of algal suspensions is the reduction in filtrate flow rate with time, associated with membrane fouling and filtercake formation. These two fouling mechanisms may occur simultaneously and have different effects on the scaling relationship of filtration rate with time, making quantitative predictions of the filtration behaviour complex. The foulants include suspended microalgal cells and their presumed Extracellular Polymeric Substances (EPS). To investigate this problem, we perform static microfiltration experiments to harvest oil-rich marine microalgae Nannochloropsis oculata. Batch filtration experiments of microalgal suspensions using glass-fibre membranes are conducted under filtration pressures varying between 0.5 and 200 kPa. Here we investigate the relative importance of potential fouling mechanisms, including pore plugging, entrance blocking, and filtercake formation. We examine variations in filtrate flux, using a novel approach involving numerical differentiation of the filtrate volume to identify how its scaling relationship with time and compare with the traditional root-time behaviour. These results are analysed with reference to the blocking filtration laws to determine the potential fouling mechanism. Rheology tests of both filtration feeds and filtrate are performed, and both optical and scanning electron microscopy are used to observe the filtercake. Our results show a significant drop in the filtrate flux after a spurt loss phase under pressure. The scaling analysis demonstrates a power law relationship between cumulative filtrate volume and time in the post-spurt phase. We show here, for the first time, that the scaling exponent varies with time, approaching a value close to 0.5 (i.e. the root-time behaviour) after a long period of time. Using the analysis, we conclude that the filtration process can be divided into various stages; a spurt loss phase when the pressure is initially applied, followed by a stage in which both internal and external filtercake formation occurs, and a final stage which is dominated by external filtercake formation (at which point root-time behaviour is observed). Furthermore, our findings suggest that fresh microalgal suspensions experienced a larger spurt loss compared to aged suspensions in microfiltration. This difference may be attributed to the limited production of EPS and microalgal debris during shorter cultivation periods. The microscopic observations reveal the invasion of microalgal cells into the membrane, which verifies the formation of an internal filtercake suggested by our scaling analysis. The contamination of the membrane increases with higher filtration pressures. Finally, we demonstrate that Fe3+ coagulant can be used to increase the microalgal particulate size before filtration, resulting in a much higher filtrate flux compared to uncoagulated suspensions. This result provides opportunities to reduce membrane contamination to a negligible level.

Feasibility evaluation of near dissolved organic matter microfiltration (NDOM MF) for the efficient removal of microplastics in the water treatment process

Microfiltration (MF) using membranes with a mean pore size smaller than 0.45 μm has generally been used for particle removal from water, given that materials larger and smaller than 0.45 μm are regarded as particulates and dissolved organic matter (DOM), respectively. It is also the case for removing small-size microplastics (MPs). However, given their sizes (ca. 1 μm), there is room for further improvement of the productivity (i.e., water flux) in the pore size range of 0.45–1 μm on the condition that the removal rate is maintained. With this in mind, MF's water flux and removal rate were tested using seven different MF membranes, and the right pore, with the size of 0.8 μm, was found for MP removal, which is called near DOM (NDOM) MF. In the filtration test using polystyrene surrogate beads with an average particle diameter of 1.20 μm, NDOM MF exhibited a 1.7 to 13 times higher permeate flux than the conventional MF using 0.1, 0.2, and 0.45 μm membranes while maintaining a higher removal rate than 2 log. The excellent removal rate of the NDOM MF was attributable to the following three factors: (1) smaller mean pore size than the average particle diameter, (2) particle screening effect enhanced by the secondary layer formed by surface deposition, and (3) 3D mesh sublayer structure favorable for capturing penetrated particles. Furthermore, the outstanding filtration performance also appeared in a low-temperature (< 10°C) process, demonstrating that NDOM MF is feasible independently of temperature. Additionally, in constant flux filtration, NDOM MF demonstrated the long-term feasibility by lowering the transmembrane pressure and specific filtration energy by more than 2 times.

Soil water percolation and nutrient fluxes as a function of topographical, seasonal and soil texture variation in Central Amazonia, Brazil

AbstractUnderstanding soil water dynamics and transport of nutrients is challenging in tropical rainforests due to the uniqueness of several properties related to soils, vegetation and seasonality that make relating patterns found in temperate environments to tropical sites difficult. We address the need for better edaphic characterization in tropical environments by investigating soil water percolation rates and chemistry across topographic, soil texture and seasonal gradients in a mature tropical rainforest in Central Amazonia, Brazil. We utilized a passive wick flux meter (e.g., drainage lysimeter) to directly measure real‐time percolation fluxes at 60‐cm depth, and to sample a suite of chemical species across plateau, slope and valley topographic positions. We found percolation flux volume and chemical exports generally increase with decreasing elevation and clay content, which was lowest in the valley. Daily percolation flux was observed to be 2.39 ± 0.44 in plateau, 3.01 ± 0.50 in slope and 6.16 ± 0.83 mm in valley. Most solutes were present in small amounts of &lt;1 mg L−1, such as PO₄3−, Fe2+/Fe3+ and Mn2+; however, NO3− concentrations were &gt;20 mg L−1, even exceeding 100 mg L−1 in the valley. Based on additional isotopic analysis, we speculate high NO3− concentrations are partially an artefact of root decomposition following installation of the flux meters. The empirical relationships we show among percolation volume and nutrient exports under varying topographies and soil textures can improve Earth System Model performance by better constraining ecohydrological relationships to nutrient fluxes, which can in‐turn better illuminate the important factors that govern their behaviour.

Enhancing Contaminant Removal in Sewage Treatment Plant Effluent with PES/Ag Membrane

In this study, a silver-infused membrane was fabricated using an ex-situ method that involved blending silver nanoparticles (AgNPs) with Polyethersulfone (PES) as the base polymer in treating sewage treatment plant (STP) effluent. Three distinct membranes denoted as S1(Ag0), S2(Ag0.5) and S3(Ag2.0) were manufactured with varying weight percentages of polymer and silver (Ag) contents. The objective was to investigate the effect of the dosage of AgNPs on membrane characterization and performance, encompassing pure water flux filtration tests, organic rejection tests, and antibacterial properties. The results showed that all PES/Ag membranes demonstrated robust performance in removing total suspended solids (TSS), chemical oxygen demand (COD), apparent colour (Hazen unit), total dissolved solids (TDS), turbidity, conductivity, total Kjeldahl nitrogen (TKN), and Escherichia coli (E. coli), complying to Class IIB (Recreational use with body contact) of the Interim National River Water Quality Standards (INWQS) for Malaysia ruled by the Department of Environment Malaysia (DOE). The results also highlighted that upon the addition of AgNPs, the E. coli removal of the membrane S3(Ag2.0) was further improved to 99.87%. The results have evidenced that the PES/Ag membranes could reject E. coli effectively, proving their value in treating bacteria-contaminated surface water. In conclusion, this study highlights the effectiveness of PES/Ag membranes as a viable solution for domestic sewage treatment, aligning with stringent water quality requirements.

Comparative study between bulk and surface modification on hy-drophobic membrane for dyeing and oily wastewater treatment

Surface modification could remarkably improve the oil–water separation ability of membrane, but suffers from limited survival positive effect layer after long-term operation. Herein, we report a systematic comparative study between bulk and surface modification (i.e., synchronous or sequential electrospun/elecrospraying) on hydrophobic polyvinylidene difluoride (PVDF) membrane. A hydrophilic UiO-66-NH2@polyacrylic acid micro/nanospheres (UiO@PAA) was selected as functional layer to improve the separation and adsorption capability of PVDF. The surface modification (SMM) and bulk modification membranes (BMM) exhibited the similar water wetting behavior in air as the same surface layer. The spider filament-like nanofibers of BMM could enhance the mechanical stability and dispersion uniformity of active sites among the PVDF fibers. In terms of oil-in-water emulsions separation ability, the BMM was superior to the SMM with the maximumly increase of separation efficiency and filtration flux to 1.3 % and 192.6 L m-2h−1, respectively. As for dye absorption, the BMM showed better adsorption capacity with a removal efficiency over 96 %. For the low concentration of methylene blue, the removal efficiency of SMM was only 94 %, while the removal efficiency of the BMM reached 98 % at room temperature. In addition, the BMM exhibited higher removal efficiency over 94 % compared with that less than 84 % of SMM after eight cycling tests, confirming its advantages in repeatability. This study demonstrates that the bulk modification can endow the initial membrane with better performance and durability, showing more promising prospects in actual wastewater treatment.

Construction of gradient SA-TiO2 hydrogel coated PVDF-g-IL fibre membranes with high hydrophilicity and self-cleaning for the efficient separation of oil-water emulsion and dye wastewater

The industrial wastewater filtered by water treatment membranes is very complex in practical applications, therefore, it is a challenge to prepare a membrane with large pore size and high flux that can efficiently separate various wastewater containing pollutants of different scales. To solve this problem, an SA-TiO2 hydrogel-coated PVDF-g-IL composite fibre membrane with super hydrophilicity, anti-pollution, and pH-responsive self-cleaning properties has been designed and prepared by electrostatic spinning and layer-by-layer coating techniques in the present work. The super hydrophilic gel layer on the surface gives the composite membrane efficient separation capability while maintaining rapid passage of the aqueous phase; the underlying PVDF-g-IL fibre membrane is positively charged and removes not only anionic/cationic pollutants by electrostatic repulsion or attraction but also creates an ionic bond with oppositely assigned SA so that the gel layer tightly bond to the base membrane. The PVDF-g-IL@SA-TiO2 membrane achieves stable and efficient separation of oil-water emulsions and dye wastewaters with a high filtration flux while retaining a retention rate higher than ∼95%. After multiple self-cleaning cycles, the ultra-thin gel layer still offers satisfactory durability with ≈100% flux recovery. This study provides a promising new strategy for designing efficient multiple contaminant separation and simpler self-cleaning membranes.

Enhanced solute transport and steady mechanical stimulation in a novel dynamic perifusion bioreactor increase the efficiency of the in vitro culture of ovarian cortical tissue strips.

Introduction: We report the development and preliminary evaluation of a novel dynamic bioreactor to culture ovarian cortical tissue strips that leverages tissue response to enhanced oxygen transport and adequate mechanical stimulation. In vitro multistep ovarian tissue static culture followed by mature oocyte generation, fertilization, and embryo transfer promises to use the reserve of dormant follicles. Unfortunately, static in vitro culture of ovarian tissue does not promote development of primordial to secondary follicles or sustain follicle viability and thereby limits the number of obtainable mature oocytes. Enhancing oxygen transport to and exerting mechanical stimulation on ovarian tissue in a dynamic bioreactor may more closely mimic the physiological microenvironment and thus promote follicle activation, development, and viability. Materials and Methods: The most transport-effective dynamic bioreactor design was modified using 3D models of medium and oxygen transport to maximize strip perifusion and apply tissue fluid dynamic shear stresses and direct compressive strains to elicit tissue response. Prototypes of the final bioreactor design were manufactured with materials of varying cytocompatibility and assessed by testing the effect of leachables on sperm motility. Effectiveness of the bioreactor culture was characterized against static controls by culturing fresh bovine ovarian tissue strips for 7days at 4.8 × 10-5m/s medium filtration flux in air at -15% maximal total compressive strain and by assessing follicle development, health, and viability. Results and Conclusions: Culture in dynamic bioreactors promoted effective oxygen transport to tissues and stimulated tissues with strains and fluid dynamic shear stresses that, although non-uniform, significantly influenced tissue metabolism. Tissue strip culture in bioreactors made of cytocompatible polypropylene preserved follicle viability and promoted follicle development better than static culture, less so in bioreactors made of cytotoxic ABS-like resin.

Facile construction of a core-shell structured metal-organic frameworks nanofiber membrane for removing Co(II) from simulated radioactive wastewater

A novel core–shell structured composite of UiO-66-Tu/PAN nanofiber membranes (NFMs) functionalized with thiourea (Tu) was developed for the efficient separation of Co(II) from simulated radioactive wastewater. Various analytical techniques were employed to characterize the structure and properties of the NFMs. The filtration performance, flux, and hydrophilicity of the membrane were evaluated using a membrane flux tester and contact angle (CA) measurements, respectively. The adsorption performance of UiO-66-Tu/PAN for Co(II) was investigated through batch adsorption experiments. The results indicate that at a UiO-66-Tu/PAN content of 7 %, the UiO-66-Tu/PAN NFMs exhibit better hydrophilicity (CA of 37.8°) and a higher cobalt ion retention rate (77.41 %). Under optimal conditions, the theoretical maximum adsorption capacity for cobalt ions is 51.2 mg/g. X-ray photoelectron spectroscopy (XPS) analysis was utilized to clarify the adsorption mechanism of Co(II) by the 7 %UiO-66-Tu/PAN composite, showing a coordination mechanism that involves the participation of oxygen, nitrogen, and sulfur atoms in the ligand. In addition, the material also demonstrates excellent radiation stability (50–100 kGy). It should be pointed out that this is the first time that metal–organic frameworks (MOFs) core–shell nanofibers membranes have been used for cobalt ion separation. The development of this new material effectively addresses the challenges associated with using MOFs as powdered adsorbents, achieving efficient purification of wastewater and providing important engineering significance for the treatment and disposal of trace amounts of 60Co radioactive wastewater.

Dynamics of soil water and nitrate within the vadose zone simulated by the WHCNS model calibrated based on deep learning

Excessive application of water and nitrogen fertilizer during farmland management practices leads to serious groundwater nitrate pollution. A field experiment was conducted during the spring maize growth period in Alxa, Inner Mongolia, China. The soil Water Heat Carbon Nitrogen Simulator (WHCNS) model was calibrated by the ensemble smoother method (ES(DL)) based on the field experiment. Then dynamics of soil water content, soil water percolation flux, soil nitrate concentration and soil nitrate leaching flux were simulated with the calibrated WHCNS model under different water and nitrogen fertilization treatments within the vadose zone. The main conclusions are as follows: ES(DL) is feasible for the calibration of the WHCNS model. RMSE_Maximum a posteriori (RMSE_MAP) of soil water content are 0.0301 cm3 cm−3 and 0.0302 cm3 cm−3 for model calibration and model validation, respectively. RMSE_MAP of soil nitrate concentration are 5.49 mg N kg−1 and 3.86 mg N kg−1 for model calibration and model validation, respectively. Both average soil nitrate concentration and average nitrate leaching flux increase with increasing irrigation amount under the same nitrogen fertilization level for the depths of 1.2 m and 1.8 m. However, average soil nitrate concentration decreased and leaching flux increased with increasing irrigation amount under the same nitrogen fertilization level for the depths of 10 m and 20 m. The study of nitrate dynamics in the deep vadose zone contributes to better understand the procedure of nitrate pollution in groundwater caused by excessive water and nitrogen application.

Combination of activated carbon/ultrafiltration as pre-treatment for seawater reverse osmosis plants

Seawater Reverse Osmosis (SWRO) is a common technology to treat seawater to comply high freshwater demand. Currently, the main issue of seawater/brackish water as the potential sources for drinking water is vulnerable to organic pollutants. An effective pre-treatment is crucial to maintain the efficiency of SWRO for sustainable operation. Optimization of the process could be performed by a hybrid membrane combination using commercial Activated Carbon (AC) with based material coconut shell/coal and Ultrafiltration membrane (UF). For hybrid process, the activated carbon was continuously dosed into the pilot scale filtration employing PES Hollow Fiber membrane with active area of 4 m² and average pore size of 10 nm that represents a real operation filtration process (i.e., filtration flux, filtration time, backwashing, and cleaning in place), and was performed until 8 filtration cycle sequence. This study investigated membrane performance with combination technique PAC/UF and GAC/UF in Pilot scale experiments within resistance membrane and retention membrane. Combination of Activated Carbon/Ultrafiltration showed synergistic effects in the removal of organic content for COD 40%-96%, UV-VIS 43%-92% and Turbidity 73%-99%. High removal of organics pollutants (COD, UV-VIS and Turbidity) was attributed to small average pore distribution of Activated Carbon (&lt;10 µm) that increase adsorption process. Moreover, hybrid Activated Carbon/UF adsorption kinetics can reduce filtration times to achieved optimal retention. Related to membrane performance, hybrid AC/UF resulted in less permeability declines almost double in first two filtration cycle and slightly less permeability decline until fifth cycle in comparison with single UF process. Better membrane performance can furtherly be explained from less irreversible fouling in case of AC/UF. Combination AC/UF enhanced the control of Irreversible fouling and resulted in better filtration performance as well as higher organic substance removal. Therefore, hybrid AC/UF could be seen as an effective system as pretreatment for SWRO.