Conventional Filtration Research Articles

Templating metal-organic framework into fibrous nanohybrids for large-capacity and high-flux filtration interception

Engineering metal-organic-frameworks (MOFs) into flexible hybrid membranes has been endeavored to entrap various molecules through a conventional filtration process. In most cases, both the rejection ratio and adsorption capacity may be limited by a low MOF loading amount, polymeric coating barrier, or large flow flux. It remains challenging to achieve the combination of large-capacity adsorption, high flux and large rejection ratio in an individual filtration setup. Herein through an in-situ templating synthesis, nanofibers of zeolitic imidazolate frame work-8 (ZIF-8) with the distinct diameters of ~20 nm and ~100 nm were produced by coating on aramid nanofibrils and silk microfibrils, respectively. With the super loading amount of ZIF-8 up to ~70 wt%, these fibrous nanohybrids enabled to produce spider-web-like membranes with both the high rejection ratio (>99%) and large flow flux (up to ~390 L m-2 h-1 bar-1 at thickness of ~120 μm). Their superior adsorption capacities for organic dyes also ensured the maintenance of high rejection ratios at high flow flux for large-volume filtration. Thus, the template of two types of nanofibrils may offer a facile method to design web-like MOF membranes with hierarchical microstructures and to intercept a large amount of specific molecules through a continuous “one-pass” filtration process for practical applications.

Magnetized orange peel: A realistic approach for methylene blue removal

Though the utilization of agricultural wastes as biosorbent has demonstrated promising results in wastewater treatment, researches on magnetized biosorbent is still limited up to now. The conventional filtration and centrifugation are commonly associated with the drawbacks of long operation hours and high energy consumption. Therefore, development of magnetized biosorbent that removes the pollutant effectively and can be recovered from treated solution in shorter time offers an interesting solution. In this research, the performance of three types of orange peel adsorbent for methylene blue (MB) removal namely, untreated orange peel (UOP), chemically treated orange peel (COP), and magnetized orange peel (MOP) was compared. Adsorption results revealed that the MB percentage removal using UOP, COP, and MOP was 92.73%, 97.86% and 91.45%, respectively. The adsorption process using MOP was then further studied as a function of pH (2–12), solid to liquid ratio (1:25–1:100), temperature (30–60 °C), contact time (20–180 min) and initial MB concentration (50–250 mg/L). The highest removal percentage for MB could be achieved at pH 8, solid to liquid ratio of 1:25, temperature of 40 °C, initial MB concentration of 50 mg/L, and equilibrium time of 40 min. The kinetic study demonstrated that Langmuir adsorption isotherm model best represented the adsorption results with the maximum monolayer adsorption capacity of 40 mg/g. The findings in this research are suggesting MOP as an inexpensive biosorbent that is effective for MB dye removal in a more realistic biosorption system.

Design of hybrid RO/NF permeate staging for the supply of clean water in Tanjung Lame Village

The groundwater sources from community wells in Tanjung Lame village, Pandeglang district, are very salty, so they are not suitable for consumption. Reverse osmosis (RO) and nanofiltration (NF) membrane are alternative desalination technologies for treating clean water from saltwater wells. However, the pressure required on a conventional single-stage RO filtration system is very high. The purpose of this study is to design a hybrid RO/NF filtration system that can operate at low pressure. The designed hybrid RO/NF permeate staging has proven to be able to produce clean water from saltwater wells in Tanjung Lame village at low pressure. To obtain optimum results, the designed hybrid RO/NF permeate staging is operated at the first and second stage pressure of 6 and 3 bar, respectively. At that pressure, the salt rejection and TDS of permeate is 97.06% and 85 ppm, respectively. The water recovery rate and permeate flow rate is 31% and 1.55 liters/minute, respectively.

Conventional filtration system for seawater pretreatment at the Beni Saf desalination plant using conventional sand filters: a comparison with Filtralite pure and clay filters

Conventional filtration system for seawater pretreatment at the Beni Saf desalination plant using conventional sand filters: a comparison with Filtralite pure and clay filters

Management of glaucoma in pregnancy - balancing safety with efficacy.

Glaucoma and pregnancy is an uncommon combination, but it constitutes a very challenging situation for the treating doctor. The challenge is not only controlling the intraocular pressure and preventing glaucoma progression in the mother, but also having to deal with her mental stress and anxiety regarding the safety of her child. The situation is further worsened by the lack of definite guidelines as to how to deal with such patients. Relative rarity of glaucoma in this population restricts any large prospective randomized clinical trials or any large systematic studies. Moreover, none of the existing anti-glaucoma medications is absolutely safe in pregnancy. Current practice patterns depend on some case reports, a few observational studies and a few animal studies that attempt at determining the safety and efficacy of the available medicines. These are then prescribed on the basis of their relative safety in any particular stage of pregnancy or lactation. Newer medications that were released recently in 2018, such as Vyzulta and Rhopressa, presently have limited data to support their safety for use during pregnancy. Laser trabeculoplasty, conventional filtration surgery (of course without anti-metabolites), and minimally invasive glaucoma surgery represent a few non-pharmacological management options. Surgical procedures such as trabeculectomy and tube-shunts or collagen matrix implants, and newer minimally invasive glaucoma surgery procedures such as the gelatin stents are currently being explored and may prove to be viable solutions for severe glaucoma during pregnancy, although they too have their own inherent drawbacks. Management of glaucoma during pregnancy and lactation requires careful consideration of the disease status, gestational stage, US Food and Drug Administration classification and guidelines, and potential benefits and limitations of the various therapeutic modalities. This review focuses on the importance of a multidisciplinary team approach, starting with preconception planning and counseling, determining the treatment options depending on the stage of glaucoma and of pregnancy, and emphasizes the involvement of the patients, their obstetrician, and pediatrician through active discussion regarding the various medical, laser, or surgical modalities currently available or under exploration for use during pregnancy and lactation. The ultimate aim is to achieve an optimal balance between the risks and benefits of any type of intervention, and to customize treatment on an individual basis in order to achieve the best outcomes for both mother and fetus.

The role of Ahmed glaucoma valve in the management of refractory glaucoma: Long-term outcomes and complications.

To retrospectively evaluate the efficacy and long-term complications of the Ahmed glaucoma valve (AGV) in refractory glaucoma. Seventy-eight eyes with glaucoma refractory to conventional surgical procedures (filtration surgery and diode laser cyclophotocoagulation) underwent AGV implantation between May 2006 and August 2018. The criteria for success were defined as an intraocular pressure (IOP) less than 18 mmHg and a decrease of at least 20% from the preoperative IOP. The criteria for failure were an IOP greater than 18 mmHg or less than 5 mmHg, an increase in medical treatment, a decrease of less than 20% of the initial IOP, the need for another glaucoma surgery, or a decrease in visual acuity attributable to the valve. IOP decreased from 31.0 ± 9.0 mmHg to 17.2 ± 7.2 mmHg (mean follow-up 32.5 months), for a mean IOP lowering of 44.5% (p < 0.001). Medical treatment was significantly reduced from 5.3 ± 1.5 to 2.8 ± 1.9 (p < 0.0001). The cumulative success rates were 59.4% at 3 years and 45.1% at 5 years. Encapsulation of the filtration bleb was the most common short-term complication (32.1%). Relevant long-term complications were bleb fibrosis with elevated IOP (12.8%) and corneal decompensation (10.2%). The AGV is an effective procedure in the long-term for controlling IOP in refractory glaucoma, with limited incidence of complications. These results suggest that the AGV might be considered earlier in the surgical strategy for glaucoma not controlled after one well-performed conventional filtration surgery.

Submerged nanofiltration without pre-treatment for direct advanced drinking water treatment

Membrane fouling is a major challenge toward achieving direct nanofiltration (NF) treatment of surface water. This study aimed to evaluate the potential of the novel submerged flat-sheet NF membrane module to achieve low fouling propensity and high separation performance during the direct filtration of surface water. Laboratory-scale NF tests showed that the transmembrane pressure (TMP) increased only by 10 kPa over 24 d during the direct treatment of river and dam water. The NF system showed high (>80%) and stable rejection of color and organics, as well as low and variable conductivity rejection (28–47%). The rejection of negatively charged trace organic chemicals (TOrCs) was >50%, while that of uncharged or positively charged TOrCs was <50%. Another NF test that was conducted at a drinking water treatment plant showed negligible membrane fouling with a TMP increase of 3 kPa over 35 d. Separation performance of the NF system remained high: total organic carbon (TOC) removal was >70%, which was greater than the conventional rapid sand filtration system with powdered activated carbon and intermediate chlorine doses (TOC removal = 20–60%). Overall, this study demonstrated high water quality and stable system operation of the submerged flat-sheet NF system during direct treatment of surface water.

PM2.5 collected using cyclonic separation causes stronger biological responses than that collected using a conventional filtration method

Evaluation of the health effects of particulate matter with aerodynamic dias. ≤ 2.5 μm (PM2.5) should reflect realistic condition in ambient atmosphere. However, using conventional filtration methods, only extracts from PM2.5 collected on the filter can be analyzed and not the particle itself. Cyclonic separation is a technique that enables the direct analysis of the effects of the crude “powder form” of PM2.5 on respiratory health. Airway epithelial cells and antigen-presenting cells were exposed to PM2.5 collected during the same period using a conventional filtration method or cyclonic separation. PM2.5 collected using cyclonic separation led to a higher secretion of interleukins 6 and 8 (IL-6, IL-8) from airway epithelial cells, and IL-6, IL-1β, tumor necrosis factor-α (TNF-α) secretion, cluster of differentiation 86 (CD86), and dendritic and epithelial cells 205 (DEC205) expression on antigen-presenting cells, compared with the effects of filter-collected PM2.5. Furthermore, PM2.5 collected using cyclonic separation increased inflammatory cytokine levels and induced lung inflammation in vivo. These results suggest that crude PM2.5 collected using cyclonic separation causes stronger biological responses than filter-collected PM2.5. Hence, PM2.5 collected using cyclonic separation can be utilized for a reliable evaluation of the health effects of ambient PM2.5.

Extraction of the natural indigo carmine pigment from the Isatis plant, characterization and dyeing of wool

Natural indigo is hardly used anymore, replaced by synthetic indigo. Considered to be more powerful and more intense. The aim of this study is to optimize the method of extracting indigo carmine from the Isatis plant located in the Timhdit region of Morocco, during the fermentation period of the extracted liquid (pH = 10) and by adding 10% sugar it was possible to increase the yield by 0.5% indigo carmine blue powder to 0.9%. The main effect of applying centrifugation at 7000 rpm instead of conventional filtration is the reduction of the time from 30 min to 5 min as well as the reduction of the loss of traces of indigo in the filter papers by easily recovering the blue powder in the form of sediment in the centrifuge tubes. The extracted pigment is characterized by the infrared which confirmed the structure of the indigo carmine obtained, by visible UV spectroscopy, the maximum absorption of which is approximately 598 nm. This blue pigment was applied to the wool fibres by optimizing the dyeing procedure (T = 50 ° C and pH=10) with a 1/100 bath ratio and a 35 min soaking time. Dyed wool sample has reached a rigid fixation confirmed by the test for fastness washing 105-C06 and to friction 105 -X12.

The evolution of botanical biofilters: Developing practical phytoremediation of air pollution for the built environment

Indoor air quality is of emerging importance due to the rapid growth of urban populations that spend the majority of their time indoors. Amongst the public, there is a common perception that potted-plants can clean the air of pollutants. Many laboratory-based studies have demonstrated air pollution phytoremediation with potted-plants. It has, however, been difficult to extrapolate these removal efficiencies to the built environment and, contrary to popular belief, it is likely that potted-plants could make a negligible contribution to built environment air quality. To overcome this problem, active green walls have been developed which use plants aligned vertically and the addition of active airflow to process a greater volume of air. Although a variety of designs have been devised, this technology is generally capable of cleaning a variety of air pollutants to the extent where comparisons against conventional air filtration technology can be made. The current work discusses the history and evolution of air phytoremediation systems from potted-plants through to practical botanical air filtration.

Superwetting TiO2-decorated single-walled carbon nanotube composite membrane for highly efficient oil-in-water emulsion separation

With the advantages of one-dimensional hollow structure, high porosity and prominent mechanical strength, single-walled carbon nanotubes (SWCNTs) have been extensively utilized to improve conventional filtration membranes for oil/water separation. Their intrinsic hydrophobicity, however, adversely affects the anti-fouling performance of the SWCNT membrane. Herein, a super-hydrophilic and underwater super-oleophobic hierarchical modified membrane with enhanced permeability and anti-fouling property was fabricated using the vacuum-assisted filtration technique by synergistically assembling SWCNTs and titanium dioxide (TiO2) nanoparticles on a cellulose acetate membrane. Highly dispersed SWCNTs were obtained by carboxylating treatment of agglomerate SWCNTs. The controlled stacking of SWCNTs fibers and a controllable amount of TiO2 rendered a modified membrane with high porosity and hierarchical structure, leading to an ultrahigh water flux up to 4,777.07 L·m−2·h−1, and excellent separation performance with efficiency greater than 99.47%. Most importantly, the membrane exhibited excellent anti-fouling ability during ten cycles with the aid of the super-wetting property of TiO2 nanoparticles. The results indicated that coating TiO2 nanoparticles on SWCNTs modified the surface topography of the obtained SWCNT/TiO2 membrane, which improved hydrophilicity, permeability and anti-fouling property, manifesting attractive potential applications in oil/water separation.

A pilot application of recycled discarded RO membranes for low strength gray water reclamation.

Reuse of recycled RO membranes after oxidative treatment as ultrafiltration membranes promise to bring membrane filtration at par with conventional treatment processes in terms of cost-effectiveness. Although the treatment process in which discarded RO membranes are converted into ultrafiltration membranes is well documented, limited pilot data are available for their application in different filtration applications. This research gap is felt because most commercially available RO membranes are spiral, wound while the ultrafiltration membranes commonly used for water filtration applications are hollow fiber. Pilot-scale data will help to develop performance guidelines and predict fouling characteristics of different types of feed waters. In the current paper, converted RO membranes are subjected to filtration with domestic gray water as the feed source. The results show that the converted membranes performed at par with conventional filtration while also providing a consistent filtrate turbidity of < 1NTU. The reduction in cost and physical footprints and recycling of membranes that would otherwise have ended up in landfills are added advantages that makes this an attractive proposition for gray water filtration applications.

Lightning generated electric field over land and sea at Northern Region of Peninsular Malaysia: Measuring Setup

Lightning is the transfer of significant charge between two charged object, it can appear between cloud-to-cloud, cloud-to-air and cloud-to-ground. All lightning activities are correlated with charge movement and therefore, it can be studied using measurement of electrostatic field (slow field changes), radiation field (fast field changes) and magnetic field affiliated with charge movement. The measuring equipment was a parallel flat plate and vertical whip antenna with an analog filter buffer circuit, connected to a digital high speed oscilloscope. In principle, both antenna have a similar measuring operation, with the exclusion of the antennas dimension, mode of transient recoder and the association of circuitry characteristic (decay time constant). This measurement setup are commonly used to perform electric field characterization related to various lightning events such as as preliminary breakdown, stepped leader, return stroke, subsequent return stroke, dart leader, dart-stepped leader, narrow bipolar pulses and cloud activity between strokes, such as regular pulse trains, K and M changes and chaotic pulse trains. The measurement systems are located very close to the sea, with respect in obtaining a perspicuous explaination of lightning propagation effects on sea instead on land. Noise-distorted effects in data captured usually introduce in a noisy environment or when the lightning strike far from the measurement station, thus the data gathered from the measurement need to be filter using MATLAB computer simulation before conducting further analysis. A promising wavelet 1-D technique, then, were used in signal denoising process rather using conventional filtration. In this works, the state of art in measuring vertical component of electric field focalized sea area during the thunderstorm days been demonstrate and explained.

Simulation of wastewater treatment processes with Bioreactor Membrane Reactor (MBR) treatment versus conventional the adsorbent layer-based filtration system (LAFS)

ABSTRACT The membrane for wastewater decontamination is an interesting alternative to conventional layered adsorbent filtration systems. Membrane bioreactors (MBRs) remove the residual biomass on the surface of the membranes irrespective of the settling properties of the sediment. Therefore, a high waste concentration as well as a low nutrient/microorganism ratio is required. In addition, the development process of a characteristic Layer Adsorption Filtration System (LAFS) community is favoured by the special properties of MBRs. This study will study the operating and treatment performance of MBR and infiltration processes and compare them with each other. The calculation was made using GPS-X software. The quality of the effluent received by the MBR system was better or equivalent to that obtained by adsorbent layer filtration (ALF). The main significant difference was the removal of total suspended solids (TSS), which reached up to 96% and also, organic matter in the MBR.

Analysis of electrokinetic response of solid-liquid mixture during expression operation

In the expression process of slurry material using a filter-press of compression type, the process is divided into two periods: the filtration period and the consolidation period. Identification of the exact time of the culmination of filtration period is essential for operating the press effectively. This study focused on the electrokinetic phenomena during expression operation of zinc oxide slurry to obtain information on the status of the filter chamber. We have measured the time course of electrical potential difference (EPD) between both ends of expressed material during the expression process using a laboratory piston press. The absolute value of EPD increased with the progress of the filtration period, followed by the decrease during the consolidation period. It was observed that the time at which the absolute value of the EPD began to decline coincided with the time at which the filtration period ended. EPD reached the plateau value at the end of consolidation. In a consolidation of homogeneous semisolid material, the absolute value of EPD increased at the beginning of the operation, followed by the decline to the plateau value. We have extended the theoretical equation of streaming potential for a straight capillary to be applied to a tortuous flow path of the expressed material. The time course of EPD can be qualitatively explained by using the proposed equation for EPD and calculated liquid pressure distributions based on the conventional filtration and consolidation theories by considering the medium resistance.

Estimation of glomerular filtration rate in patients with cirrhosis: evaluation of equations currently used in clinical practice and validation of Royal Free Hospital cirrhosis glomerular filtration rate

Conventional creatinine-based glomerular filtration rate (GFR) equations have been reported to overestimate renal function in patients with cirrhosis. The Royal Free Hospital (RFH) cirrhosis GFR equation was developed to accurately estimate GFR in this population. The aim of this study was to evaluate the ability of widely available equations [Chronic Kidney Disease Epidemiology Collaboration equation (CKD-EPI), Modification of Diet in Renal Disease equations (MDRD-4, MDRD-6)] and the RFH equation to correctly estimate the GFR of patients with cirrhosis. We retrospectively analyzed data from patients with cirrhosis who underwent measurement of GFR with the use of 51Cr-EDTA (GFR-M). The CKD-EPI, MDRD-4, MDRD-6 and RFH equations were calculated, while bias, precision and accuracy were estimated for each one of them and then compared with paired t-tests. Bias was defined as the mean difference between the GFR-M and the result of each equation; precision was defined as the SD of the differences and accuracy was defined as the square root of the mean squared error (mean of the squared differences). Higher values are associated with worse bias and better precision/accuracy. One-hundred and thirty-four cirrhotic patients were included. Bias was estimated for CKD-EPI, MDRD-4, MDRD-6 and RFH at -5.91, -3.13, 0.92 and 18.24, respectively. Significant differences were observed between all equations (P < 0.001). Regarding precision, only the comparison between MDRD-4 (20.81) and RFH (16.6) yielded a statistically significant result (P = 0.037). Finally, CKD-EPI (19.32) and MDRD-6 (18.81) exhibited better accuracy than GFR-RFH (24.61) (P = 0.006 and 0.001). RFH demonstrates inferior accuracy in predicting renal function in patients with cirrhosis, in comparison to conventional equations.

Fabrication and characterization of functionalized multi-walled carbon nanotube mixed-matrix membrane for treating biochemical and chemical oxygen demands of surface waters

In this work, a mixed-matrix (MM) membrane consisting of functionalized multi-walled carbon nanotube (MWCNT), polyethersulfone (PES) and polyester non-woven fabric was fabricated using immersion precipitation. The membrane capability in reducing the biochemical oxygen demand (BOD) and chemical oxygen demand (COD) levels of the surface water samples collected from rural areas in Sarawak, Malaysia are tested. MWCNTs were functionalized using chemical oxidation to promote functional group onto their sidewalls. Raman analysis reveals a higher peak in D-band than G-band in the functionalized CNT but the higher ID/IG intensity ratio was demonstrated by CNT treated with strong acid. Surface morphological characterization verified the existence of the defects in CNT structures, which was reflected on the sidewall defects, debundling and shortening of the MWCNTs. Meanwhile, the surface waters were tested for BOD and COD levels and treated with three different types of membrane by conventional vacuum filtration. Membrane of raw MM displayed the best treatment capability which is reflected on its ability to maintain the BOD level and reduce the COD level with a consistent percentage. Thus, this work provides a different insight in membrane capability in treating BOD and COD levels in surface waters.

Scalable Manufacturing of MXene Films: Moving toward Industrialization

Industry-scale manufacturing techniques hold the key to the ultimate commercialization of MXene products. In Matter, Taylor, Gogotsi, and colleagues demonstrate a drop-casting method to prepare scalable and micro-patternable MXene films on hydrophobic substrates, highlighting the excellent potential for the commercial application in electromagnetic interference shielding.

Cyanobacteria bloom variations and atmospheric variables, an environmental health contribution

Urbanization in river basins contributes to the anthropogenic eutrophication of their water bodies, leading to the proliferation of toxic algae such as cyanobacteria. There is a characteristic pattern of seasonality in algal blooms and cyanobacterial communities, although these algae may be present or even dominant for most of the year, causing practical problems associated with high cyanobacterial biomass and potential health threats. The increased concentration of toxins originating from these algae, cyanotoxins, in water-supply reservoirs puts the population at serious risk, since they are not removed by conventional treatment and filtration. This study analyzed possible associations between climate elements and cyanobacteria biomass in the Guarapiranga dam reservoir, located in the metropolitan region of São Paulo, Brazil. Meteorological variables were studied exclusively in relation to the cyanobacteria biomass, in order to perceive the influence of weather and climate in this complex system and to provide data for modeling future climate change scenarios. For this purpose, cyanobacteria count data were used for the period from 2010 to 2016, grouped by month, in addition to the atmospheric variables. The strongest correlation with the blooms was with Irradiation and Total Rainfall, explaining 30% of cases of the occurrence of cyanobacteria proliferation at the point of collection GU 101. Despite the notable influence of climatic seasonality on the algae blooms, this difference varies and is not homogeneous, depending on the location and the species studied.

Design and Validation of Passive Environmental DNA Samplers Using Granular Activated Carbon and Montmorillonite Clay

Environmental DNA (eDNA) analysis is gaining prominence as a tool for species and biodiversity monitoring in aquatic environments. eDNA shed by organisms is captured in grab samples, concentrated by filtration, extracted, and analyzed using molecular methods. Conventional capture and filtration methods are limited because (1) filtration does not capture all extracellular DNA, (2) eDNA can degrade during sample transport and storage, (3) filters often clog in turbid waters, reducing the eDNA captured, and (4) grab samples are time sensitive due to pulse eDNA inputs. To address these limitations, this work designs and validates Passive Environmental DNA Samplers (PEDS). PEDS consist of an adsorbent-filled sachet that is suspended in water to collect eDNA over time. Both extracellular and cellular DNA are captured, and the extracellular DNA is protected from degradation. The eDNA captured over time may be more representative than a grab sample. Two adsorbents, Montmorillonite Clay (MC) and Granular Activated Carbon (GAC), are tested. In laboratory experiments, MC-PEDS adsorbed five times more extracellular DNA and desorbed up to four times more than GAC-PEDS (despite high levels of eDNA loss during desorption). In microcosm and field experiments, GAC-PEDS captured over an order of magnitude more eDNA than MC-PEDS. Field results further validated PEDS as an effective eDNA capture method compared to conventional methods.