Saturated Filter Research Articles

Influence of pre-dewatering on the success of cake washing

ABSTRACT Cake washing is one key challenge after filtration. It is used to improve the product quality of filter cakes. Many studies deal with washing of saturated filter cakes and are used as the basis for cake washing models. However, to avoid mixing of supernatants (e.g. suspension liquid and wash liquid) on the cake surface during production processes, the cake is pre-dewatered and thus the pores are undersaturated. This paper demonstrates the influence of different start saturations (different pre-dewatering times) on the displacement regime of a washing curve compared to washing saturated filter cakes. An increase in saturation (filling) also takes place at the beginning of the washing of undersaturated filter cakes. A new filling regime located at the beginning of the washing process is clearly defined before the known displacement regime. The extent of the filling regime depends mainly on the initial saturation before washing process.

Preparation of filter by alkali activation of blast furnace slag and its application for dye removal

This study demonstrates a high-value valorization of blast furnace slag in foamed alkali-activated filters for adsorption applications, using methylene blue as a model compound. The filters were prepared by combining alkali activation of blast furnace slag with direct foaming, followed by curing at 60 °C for 4 h. Five different surfactants were compared for the stabilization of foams. Based on an initial screening, the Triton X-405 surfactant was selected for further studies. The dosages of selected surfactant and H2O2 were optimized to obtain compressive strength of 2.59 MPa and specific surface area of 83.3 m2/g for powdered material and 78.31 m2/g for foam pieces. Porosity was determined as 64%, 65%, or 50% by using gas pycnometry, Archimedes method, or X-ray microtomography, respectively. The optimized filter mix design was applied for methylene blue removal in continuous column experiments at two influent concentrations (5 and 10 ppm) by using constant empty-bed contact time of ~9 min (flowrate of ~1 L/h). After 6 h, for both influent concentrations, the dye removal was still 74%, with the initial removal of ~100%. The saturated filter could be regenerated by a thermal treatment resulting improved adsorption performance. When the material was employed as powder, the maximum adsorption capacity was 60.35 mg/g according to the Langmuir isotherm (R2 = 0.99) and adsorption kinetics followed the pseudo-second order model. The results demonstrate preliminarily that porous filters prepared in this study have potential to be used in industrial wastewater treatment.

Employing Constant Rate Filtration To Assess Active Pharmaceutical Ingredient Washing Efficiency.

Washing is a key step in pharmaceutical isolation to remove unwanted crystallization solvents and dissolved impurities (mother liquor) from the active pharmaceutical ingredient (API) filter cake to ensure the purity of the product whilst maximizing yield. It is therefore essential to avoid both product dissolution and impurity precipitation during washing, especially precipitation of impurities caused by the wash solvent acting as an antisolvent, affecting purity and causing agglomerate formation. This work investigates the wash solvent flow through a saturated filter cake to optimize washing by displacement, taking account of diffusional mechanisms and manipulating the wash contact time. Constant rate filtration/washing is employed in this study using readily available laboratory equipment. One advantage of using constant rate filtration in this work is that it allows for the collection of separate aliquots during all stages of filtration, washing, and deliquoring of the API cake. This enables a wash profile to be obtained, as well as providing an overall picture on the mass of API lost during isolation and so can assist in optimizing the washing strategy. Particle size analysis of damp cake obtained straight after washing is also performed using laser diffraction. This allowed for agglomerate formation caused during washing to be distinguished from agglomeration that would be caused by subsequent drying of the wet filter cake. This work aims at improving pharmaceutical product quality, increasing sustainability, and reducing manufacturing cost.

Effect of operating mode on the performance of sand filters treating greywater.

A long-duration laboratory study spanning more than 6 months was conducted to evaluate the effect of operating mode on the performance of sand filters for greywater treatment. Performance of saturated and unsaturated filters operated in continuous or intermittent mode was evaluated using settled real greywater. Effects of pause period and higher loading rate on their performance were also evaluated. Furthermore, the effect of the depth of the filter medium on the performance of the filters was also assessed. The saturated filters operated continuously or intermittently performed significantly better than the respective unsaturated filters. Saturated continuous (SC) and unsaturated intermittent (UI) filters were the best and worst performers amongst the different filters. SC filter removed on an average 98% turbidity, 76% BOD, 88% COD, 84% ammonia-N (NH4-N) and 95% phosphate (PO4-P). Up to 99.68% (2.40 log) removal of faecal coliforms was also achieved by this filter. SC filter showed stable and reliable performance as its effluent quality was insensitive to fluctuations in influent quality. The pause period significantly affected the removal of some of the parameters. Doubling the hydraulic loading rate significantly affected the performance of continuous filters. Though most of the pollutant removal occurred in the top 10 cm in all the filters, a depth of 50 cm was found optimum for the removal of different pollutants. Whilst all the filters produced effluent conforming to different reuse standards except microbial standards, saturated continuous filter (SC) could also meet the faecal coliform standards towards the end of the filter operation.

Evaluation of the fertiliser replacement value of phosphorus-saturated filter media

The use of filter media to adsorb phosphorus (P) from nutrient-rich waters is an effective, simple and low-cost method to recover and reuse P as an inorganic fertiliser replacement. Although it is assumed that the saturated filter media can be applied to cropland as a safe fertiliser replacement, there is presently a lack of information on the fertiliser replacement value (FRV) of such products and their negative effects on plants and soil. Therefore, the aims of this paper were to evaluate the (1) P removal capacity and plant response to soil application of waste media from three sectors (industry, agriculture, and construction and demolition), and natural and synthetic materials (2) potentially confounding risks arising from the reuse of media as a fertiliser replacement, and (3) factors affecting their fertilising efficiency once applied to soil. The predominant factors affecting the FRV of P-saturated media were their adsorption capacity and chemical composition, soil pH, and composition of water used for saturation. Some measures to overcome the negative impacts of the land application of P-saturated media include selecting the most appropriate soil-filter material combinations, the use of P solubilising microorganisms, and mixing with manure before land application. Despite confounding factors and a lack of information on the performance of some media under comparable study conditions, this study found that there is a significant potential for P-saturated filter media to partially replace the use of P mineral fertilisers and aid in the attainment of a “circular economy” in agriculture.

Impact of Filtration Conditions on Air Quality in an Operating Room

The aim of this study was to assess the impact of ventilation and filtration conditions on particle concentrations in an orthopedic operating room. Total particle, viable particle, and CO2 concentration were measured under three different situations, namely before air filter replacement, after air filter replacement, and in an operating room with a new air conditioning system. Before air filter replacement, the mean values of airflow, total particle concentration, and viable particle concentration were 706 m3/h, 15.0 × 106 ± 4.0 × 106 particles/m3, and 57 CFU/m3, respectively. After replacement, the airflow increased to 1954 m3/h, and total and viable particle concentrations decreased to 0.4 × 106 ± 0.2 × 106 particles/m3 and 24 CFU/m3, respectively. In the room with a new air conditioning system, the airflow was 2051 m3/h, and total and viable particle concentrations were 0.3 × 106. ± 0.1 × 106 particles/m3 and 15 CFU/m3, respectively. The CO2 levels were 663 ppm (before), 659 ppm (after), and 574 ppm (new room). The results showed that inappropriate or no maintenance of filters in an air conditioning system had significant negative effects on indoor air quality in operating rooms. Air conditioning systems operating with saturated filters can be affected by pressure drop, which can lead to a reduction in airflow, thereby resulting in an increase in the average total particle and viable particle concentrations and the risk of infection in operating rooms. However, the results showed that the CO2 concentration was not affected by the filter replacement.

To the question of concrete creep in the soil environment

Introduction. Concrete creep coupled with specific soil properties represent a problem for the analysis of reinforced concrete structures in geotechnical engineering. The mission of this research is to make a problem statement and to outline its potential solutions.
 Materials and methods. In the course of the research, the finite element method was applied and the review of works, covering various problem aspects, was performed.
 Results. Concrete creep in respect of a diaphragm wall is most vividly manifested in deflections and stresses in struts; as for piles, concrete creep is manifested by the longitudinal axial force distribution along the length. The co-authors have demonstrated that is necessary to single out the excavations device under bentonite slurry protection from the viewpoint of the construction technology. In this case, a 5–10 mm thick water-saturated filter cake is formed at the contact between soil and concrete. The filter cake retains its permanent water penetrability at some level that depends on pressure and injection time; therefore, concrete in trench cannot be considered isolated from filtration water flows. Following the concrete mix casting into the trench, water saturated filter cake is consolidated, and this enables the authors to make a conclusion about its resistance to vapour penetration.
 Conclusions. If water saturation is equal to Sr > 0.5–0.6 and if excavation works are performed under the protection of the bentonite slurry, relative air humidity of soil RH can be considered to be equal to 100 %, and if water saturation Sr < 0.5–0.6, RH needs to be analysed. Identification of concrete moisture content depending on relative air humidity, the groundwater filtration flow and influence of the filter cake at the contact between ground and concrete make it possible to take account of the effect of soil conditions on concrete creep.

Easton collapses and a strongly saturated filter

We introduce the Easton collapse and show that the two-stage iteration of Easton collapses gives a model in which the successor of a regular cardinal carries a strongly saturated filter. This allows one to get a model in which many successor cardinals carry saturated filters just by iterating Easton collapses.

OC4. Abstract Title: Thrombus Stability Explains the Factor V Leiden Paradox: A Mouse Model

<h3>Background</h3> Factor V Leiden (FVL) is an inherited autosomal dominant condition that is identified in 20%-50% of patients with venous thromboembolic diseases and 5-8% of the population in Canada. People with FVL are often called hypercoagulable, and have a five-fold increase in the risk of venous thrombosis. There is a low prevalence of FVL among patients with fatal pulmonary embolism (PE) and a higher incidence of deep vein thrombosis (DVT) than PE in patients with FVL. This has been referred to as the FVL paradox in thrombosis. We wished to test whether FVL and normal patients are at the same risk of initial thrombus formation, expect FVL patients present with symptomatic DVT while normal patients do not present, because the small asymptomatic DVT in normal patients embolizes to become an asymptomatic PE. <h3>Aim</h3> Therefore, to explain why patients with FVL are more likely to present with a DVT rather than a PE we will study DVT stability in FVL mice using a modification of our previously published mouse model of venous thrombus stability. <h3>Methods</h3> Platelets were fluorescently labeled using CD41 fab fragments conjugated to an Alexa Fluor 488. DVT was induced using a ferric chloride saturated filter paper on the femoral vein of female mice. We chose conditions such that only a small thrombus developed in wild type (WT) mice, and then compared them to thrombi in FVL heterozygous (F5L/+) and FVL homozygous (F5L/L) mice. Intravital videomicroscopy recorded embolic events leaving the thrombus and the thrombus sizes every 10 minutes for 2 hours. Lungs were harvested sectioned and stained for presence of PE. <h3>Results</h3> Although thrombus size remained small in WT mice, it significantly increased over time in F5L/+ and F5L/L mice. The number of total and large embolic events, and the percent of thrombus that embolized was significantly decreased in F5L/+ and F5L/L mice compared to WT mice. Previously we have correlated increased large embolic events with increased PE burden. FVL mice had significantly reduced PE burden compared to WT mice. Mice with F5L had higher F1.2 levels than in WT, consistent with increased thrombin generation. <h3>Conclusion</h3> This suggests that in noncarriers (reflected by WT), a minor insult initially resulting in a small DVT tends to remain small and asymptomatic, due to the embolization. Alternatively, the same insult in people with FVL (reflected by F5L/L) leads to thrombus growth due to less embolization and thus development of symptomatic DVT, but no PE.

Characteristics of a Filter Module Adsorption for Fine Dust Removal on Road

In this study, a electrostatic filter which could be applicable to road environment was developed and evaluated in adsorption capacity. The evaluation were performance for removal by particle size and adsorption amount by pressure using ASERAE 52.1 and 52.2. The range of size for removal test was 0.3 μm~10.0 μm which had 12 steps. The filter showed 91.3% removal efficiency from 2.5 μm and under the size, average 53.5% proportional to decreasing size value. The weight removal was 96.7% from 22.6 mmaq, initial pressure to 35 mmaq, end pressure with 715.9 g/m2, the adsorption amount. The shape of isotherm was expressed as Langmuir’s one. After washing saturated filter with dust to end pressure, the initial pressure and adsorption amount of the filter showed a light drop with no removal efficiency decline. Key words: Fine Dust, Langmuir Isotherm, Filter Panel, ASHRAE 52.1, ASHRAE 52.2

Treatment of potato farm wastewater with sand filtration

ABSTRACTThis study examined sand filtration as a component of a potato farm wastewater treatment system. Two different sand filter designs, saturated flow and unsaturated flow, were evaluated at three different loading rates: 34, 68, and 136 L m−2 d−1. Filter design had a significant effect, with unsaturated flow sand filters having significantly (p < .05) better total suspended solids (TSS) removal (89%) than saturated flow sand filters did (79%). Loading rate also had a significant (p < .05) effect, given that the lowest loading rate had higher mass removal for TSS than the higher loading rates did. Overall, all sand filters removed TSS, 5-d biochemical oxygen demand, and total phosphorus well (62–99%). Total nitrogen removal was twice as high in unsaturated flow filters (53%) than in saturated flow filters (27%), because of the recurring cycle of aerobic and anaerobic conditions during sand saturation and drying in unsaturated flow sand filters.

Characterization of Landsat-7 to Landsat-8 reflective wavelength and normalized difference vegetation index continuity.

At over 40 years, the Landsat satellites provide the longest temporal record of space-based land surface observations, and the successful 2013 launch of the Landsat-8 is continuing this legacy. Ideally, the Landsat data record should be consistent over the Landsat sensor series. The Landsat-8 Operational Land Imager (OLI) has improved calibration, signal to noise characteristics, higher 12-bit radiometric resolution, and spectrally narrower wavebands than the previous Landsat-7 Enhanced Thematic Mapper (ETM+). Reflective wavelength differences between the two Landsat sensors depend also on the surface reflectance and atmospheric state which are difficult to model comprehensively. The orbit and sensing geometries of the Landsat-8 OLI and Landsat-7 ETM+ provide swath edge overlapping paths sensed only one day apart. The overlap regions are sensed in alternating backscatter and forward scattering orientations so Landsat bi-directional reflectance effects are evident but approximately balanced between the two sensors when large amounts of time series data are considered. Taking advantage of this configuration a total of 59 million 30m corresponding sensor observations extracted from 6,317 Landsat-7 ETM+ and Landsat-8 OLI images acquired over three winter and three summer months for all the conterminous United States (CONUS) are compared. Results considering different stages of cloud and saturation filtering, and filtering to reduce one day surface state differences, demonstrate the importance of appropriate per-pixel data screening. Top of atmosphere (TOA) and atmospherically corrected surface reflectance for the spectrally corresponding visible, near infrared and shortwave infrared bands, and derived normalized difference vegetation index (NDVI), are compared and their differences quantified. On average the OLI TOA reflectance is greater than the ETM+ TOA reflectance for all bands, with greatest differences in the near-infrared (NIR) and the shortwave infrared bands due to the quite different spectral response functions between the sensors. The atmospheric correction reduces the mean difference in the NIR and shortwave infrared but increases the mean difference in the visible bands. Regardless of whether TOA or surface reflectance are used to generate NDVI, on average, for vegetated soil and vegetation surfaces (0 ≤ NDVI ≤ 1), the OLI NDVI is greater than the ETM+ NDVI. Statistical functions to transform between the comparable sensor bands and sensor NDVI values are presented so that the user community may apply them in their own research to improve temporal continuity between the Landsat-7 ETM+ and Landsat-8 OLI sensor data. The transformation functions were developed using ordinary least squares (OLS) regression and were fit quite reliably (r 2 values >0.7 for the reflectance data and >0.9 for the NDVI data, p-values <0.0001).

Investigation of the Consolidation Drainage of High Water Content Clay by Siphon Method through Unsaturated Filter

Recently, the disposal of dredged soil has become a worldwide problem. In order to utilize high water content soil material, it is essential to dewater and increase the soil strength. There are urgent demands for developing an alternative new method to dewater the dredged soils in more economical and environment friendly standpoint. Furthermore, by using adsorption effect of porous material such as granular blast furnace slag, there is possibility to establish purification technology of contaminated soil.In this paper, the siphon method is proposed to dewater the high water content dredged soil with horizontally installed plastic board drain and filter material. In order to investigate the availability and effectiveness of this method, series of tests were conducted to investigate the dewatering behaviour and strength of dredged soil with vacuum and siphon methods by using different materials as filter, such as Toyoura sand, zeolite, granular blast furnace slag. High water content dredged soil can be consolidated by using siphon method with saturated filter material such as Toyoura sand. However, it was impossible to dewater dredged soil by using siphon method with unsaturated porous filter material. The water retention tests of soil by using centrifuge method was performed to clarify the mechanism of preventing consolidation dredged soil. The test cannot find an accurate soil-water retention curve of dredged soil because of volume change.The water retention test by suction method was performed and clarify the mechanism that prevents consolidation dredged soil. The cause that prevents consolidation of dredged soil has been presumes by clarifying the air entry value. In addition, degree of saturation and suction in dredged soil and filter material has been clarified by using aquameters. The examination whether consolidation of dredged soil on various conditions focused on height of dredged soil and filter material is performed based on the revealed mechanism.

A switchable dual-wavelength erbium-doped fiber laser based on saturable absorber and active optical fiber ring filter

A dual-wavelength erbium-doped fiber laser (EDFL) with outstanding stability is presented. In the fiber laser system, two nested active optical fiber ring filters are configured to improve the comb spectrum performance, a saturable absorber is employed to form a gain grating for both filtering and frequency stabilizing, two cascaded fiber Bragg gratings (FBGs) are utilized to achieve dual-wavelength output, and a variable attenuator is arranged to adjust output power. Experimental results illustrate that the peak wavelength drift is less than 3 pm, and a good linear relationship between output power and pump power is realized.

Influence of flow-interruption on filter performance during the filtration of liquid aerosols by fibrous filters

This study investigated the influence of flow interruptions on the filtration performance of two different multi-layered fibrous filters during liquid aerosol filtration. It was found that both types of filters experienced a significant secondary loading stage, though they had reached a steady state for continuous flow. The filters showed distinctive increases in pressure drop and filter saturation until a second equilibrium state was reached. This second equilibrium state was attributed to a rearrangement of liquid in the filter during the breaks, clogging previously free passages. The ratio of shear and capillary forces was found to determine whether these passages were able to be “cleaned” once airflow was recommenced. Based on these findings, the airflow required to clean fully saturated filters was investigated and a phenomenological model developed to describe this behaviour. Furthermore, it was found that filters could be cleaned and reused, whereby they would return to one of the previous steady states (continuous or discontinuous flow). The experiments conducted in this work represent a more realistic test for oil-mist (or coalescing) filters than typical laboratory testing. Furthermore, it is hoped that they will help to bridge the gap between laboratory and field test results.

Effects of antisense-mediated inhibition of 11β-hydroxysteroid dehydrogenase type 1 on hepatic lipid metabolism

11β-hydroxysteroid dehydrogenase 1 (11β-HSD1) converts inactive 11-keto derivatives to active glucocorticoids within tissues and may play a role in the metabolic syndrome (MS). We used an antisense oligonucleotide (ASO) to knock down 11β-HSD1 in livers of C57BL/6J mice consuming a Western-type diet (WTD). 11β-HSD1 ASO-treated mice consumed less food, so we compared them to ad libitum-fed mice and to food-matched mice receiving control ASO. Knockdown of 11β-HSD1 directly protected mice from WTD-induced steatosis and dyslipidemia by reducing synthesis and secretion of triglyceride (TG) and increasing hepatic fatty acid oxidation. These changes in hepatic and plasma lipids were not associated with reductions in genes involved in de novo lipogenesis. However, protein levels of both sterol regulatory element-binding protein (SREBP) 1 and fatty acid synthase were significantly reduced in mice treated with 11β-HSD1 ASO. There was no change in hepatic secretion of apolipoprotein (apo)B, indicating assembly and secretion of smaller apoB-containing lipoproteins by the liver in the 11β-HSD1-treated mice. Our results indicate that inhibition of 11β-HSD1 by ASO treatment of WTD-fed mice resulted in improved plasma and hepatic lipid levels, reduced lipogenesis by posttranslational regulation, and secretion of similar numbers of apoB-containing lipoproteins containing less TG per particle.

A Generalized Bloom Filter to Secure Distributed Network Applications

Distributed applications use Bloom filters to transmit large sets in a compact form. However, attackers can easily disrupt these applications by using or advertising saturated filters. In this paper we introduce the Generalized Bloom Filter (GBF), a space-efficient data structure to securely represent a set in distributed applications, such as IP traceback, web caching, and peer-to-peer networks. Different from the standard Bloom filter, the GBF has an upper bound on the false-positive probability, limiting the effect of these attacks. The key idea of the GBF is to not only set, but also reset bits of the filter at each insertion. This procedure limits the false positives at the expense of introducing false negatives in membership queries. We derive expressions for the false-positive and false-negative rates and show that they are both upper-bounded in the GBF. We conduct simulations that validate the derived expressions and explore the tradeoffs of this data structure.

Filter bed systems treating domestic wastewater in the Nordic countries – Performance and reuse of filter media

Nine filter beds have been constructed in the Nordic countries, Denmark, Finland, Norway and Sweden. Filter beds consist of a septic tank followed by an aerobic pre-treatment biofilter and a subsequent saturated flow grass-covered filter. Thus, filter beds are similar to subsurface flow constructed wetlands with pre-treatment biofilters, but do not have wetland plants with roots submerged into the saturated filter. All saturated filters contain Filtralite ®P, a light-weight expanded clay aggregate possessing high phosphorus sorption capacity. The filter bed systems showed stable and consistent performance during the testing period of 3 years. Removal of organic matter measured as biochemical oxygen demand (BOD) was >80%, total phosphorus (TP) >94% and total nitrogen (TN) ranged from 32 to 66%. Effluent concentrations of fecal indicator bacteria met the European bathing water quality criteria in all systems. One system was investigated for virus removal and somatic viruses were not detected in the effluent. The investigations revealed that the majority of the BOD and nitrogen removal occurred in the pre-treatment filters and the phosphorus and bacteria removal was more prominent in the saturated filters. The saturated filters could be built substantially smaller than the current design guidelines without sacrificing treatment performance. The used filter material met the Norwegian regulations for reuse in agriculture with respect to heavy metals, bacteria and parasites. When saturated with phosphorus, the light-weight aggregate, Filtralite ®P used in the saturated bed is a suitable phosphorus fertilizer and additionally has a liming effect.

Filter materials for phosphorus removal from wastewater in treatment wetlands—A review

This paper aims to collect and analyse existing information on different filter media used for phosphorus (P) removal from wastewater in constructed wetlands. The most commonly used materials are categorized as natural materials (considered in 39 papers), industrial byproducts (25 papers) and man-made products (10 papers). A majority of studies on sorbents have been carried out in lab-scale systems as batch experiments, and only very few studies have highlighted results on full-scale systems. Among the great variety of filter media studied, most of materials had a pH level >7 and high Ca (CaO) content. The highest P-removal capacities were reported for various industrial byproducts (up to 420 g P kg −1 for some furnace slags), followed by natural materials (maximum 40 g P kg −1 for heated opoka) and man-made filter media (maximum 12 g P kg −1 for Filtralite). We found a significant positive Spearman Rank Order Correlation between the P retention and CaO and Ca content of filter materials ( R 2 = 0.51 and 0.43, respectively), whereas the relation of P retention to pH level was weak ( R 2 = 0.22) but significant. There is probably an optimal level of hydraulic loading rate at which the P removal is the highest. Additional important factors determining the applicability of filter materials in treatment wetlands such as saturation time, availability at a local level, content of heavy metals, and the recyclability of saturated filter media as fertilizer should be taken into consideration.

An environment for complex behaviour detection in bio-potential experiments

We propose BioS (Bio-potential Study) as a new virtual data analysis and management environment. It was devised to cope with the physiological signals, in order to manage different data using advanced methods of analysis and to find a simple way to decode and interpret data. BioS has been structured as a flexible, modular, and portable environment. It includes several modules as data importing and loading, data visualization (1D, 2D, 3D), pre-processing (frequency and saturation filtering, statistical analysis), spatiotemporal processing such as power spectrum, independent component analysis (ICA) in spatial and time domain, and nonlinear analysis for the extraction of the maximum Lyapunov exponent and d-infinity using optimized algorithms. The environment provides a user-friendly Graphic User Interface that allows inexperienced users to perform complex analyses and to speed up experimental data processing.