Fine Filter Research Articles

Performance comparison of sand and fine sawdust vermifilters in treating concentrated grey water for urban poor

A comparative investigation was conducted for 10 months with sand and fine sawdust vermifilters and a control unit to treat concentrated grey water generated from a poor urban household in Ouagadougou, Burkina Faso. Each of the filters was made up of cylindrical DN200-PVC pipes and filled with 10 cm of gravel at the bottom. On top of the gravel layer, filter 1 (fully sand, F1) was completed with 40 cm of sand and 10 cm of fine sawdust, filter 2 (partially sand, F2) with 20 cm of sand and 30 cm of fine sawdust, respectively, and filter 3 (fully sawdust, F3) and 4 (control, F4) with 50 cm of fine sawdust only. Two hundred Eudrilus eugeniae earthworms were inoculated in each of the vermifilters. The vermifiltration system was supplied with grey water four times per day at a hydraulic loading rate of 64 L/m2/day on a batch basis. The removal efficiencies of biological oxygen demand, total chemical oxygen demand, and dissolved chemical oxygen demand (dCOD) by the vermifilters were 25–30% higher than the control, but little differences were observed in terms of total suspended solids and coliform removal efficiencies. Though there was no significant difference in the performance of the three vermifilters (p > 0.05), except for dCOD removal efficiency, the lifespan of F2 and F3 was longer than that of F1. Therefore, fine sawdust can substitute sand as a filter medium in vermifilters.

Current capacity to conduct ecologically sustainable forest management in northeastern Canada reveals challenges for conservation of biodiversity

Long-term exploitation of boreal ecosystems often results in a reduced range of ecological conditions that threatens several species. In most boreal jurisdictions, the northern extent of commercial forestry corresponds to economical rather than ecological considerations. Our general objective is to offer guidance for sustainable boreal forest management by using a biodiversity criterion based on three indicators. The first two indicators are part of a coarse filter referring to the proportion and fragmentation of tall, dense forest habitats, whereas a third one uses a fine filter for specific requirements of boreal caribou. We applied the methodology with and without anthropogenic disturbances on 1114 land districts to contrast the preindustrial potential and current capacity of Quebec’s boreal forest to support forest management. Originally, 826 districts (74%) were above the 20% cutoff value for the minimum proportion of tall, dense forest habitats. Among the 567 districts currently under forest management, 45 did not reach this value because of past anthropogenic disturbances. Originally, 88% of the districts had sufficient undisturbed habitats to maintain caribou populations, but anthropogenic disturbances reduced this proportion to 51%. The proposed methodology could contribute to delineating areas where sustainable forest management can be implemented. Our results also clearly show that management targets of the last decades were insufficient to prevent loss of habitats below strict minimum ecological thresholds. Our approach offers a general framework that could be adapted to other forested regions to attain similar biodiversity conservation objectives.

Adsorption and adhesiveness of kapok fiber to different oils

Adsorption and adhesiveness of single kapok to various oils, such as diesel, vegetable oil, used motor oil and motor oil were quantitatively evaluated by size and adhesive energy distribution of adsorbed oil droplets on fiber via drop-on-fiber micro-sorption experiments based on Carroll’s theory of droplet morphology. Meanwhile, another micro polyester fiber was investigated as comparison. It was found that kapok fibers exihibited low surface energy of 40.64mN/m with highly hydrophobicity and oil wettability. It had high water contact angle up to 151°, adsorbing four oils with average droplet size varying from emulsified state(0.1–25μm) to dispersed state (25–100μm). The average adhesive energies of kapok to four oils were 3.78×10−11–9.40×10−11J, with the highest for vegetable oil. Compared with kapok, polyester fiber adsorbed a large number of smaller oil droplets with their average size within emulsified state for its large specific surface area contributed by micro-fine of the fiber, but showed bad adhesiveness to retain the adsorbed oils with average droplet adhesive energy among 1.49×10−11–2.27×10−11J due to its relative higher surface energy of 59.15mN/m. It is more suitable to be used as filter for secondary fine filtration under low inflow rate.

Dewatering effect of fine coal slurry and filter cake structure based on particle characteristics

An experimental study of the filtration dewatering of fine coal focusing on particle characteristics was carried out. The dewatering behavior was determined by filtration velocity, moisture content and resistance of cake using a vacuum filtration cell. The suitable filtration conditions were explored, the particle grain sizes were tested and filter cake structures were modulated, and the optimum structure of cake modified with kerosene and flocculant agents was determined. Overall, it is found that the amount of the feed particles under 0.045 mm and the uniformity of the feed particles have a direct bearing on the dewatering efficiency. The best filtration enhancement was achieved by the addition of kerosene, which yielded cake moisture ranging from 27.53% to 23.12% compared without any agents.

Large scale poly(vinyl alcohol-co-ethylene)/TiO2hybrid nanofibrous filters with efficient fine particle filtration and repetitive-use performance

A high-yielding nanofiber-based filtration material with excellent performance was developed and provides a promising way to control the severe air pollution at present.

Understanding Primary Treatment Performance and Carbon Diversion Potential of Rotating Belt Filters Using Computational Fluid Dynamics

Rotating belt filters (RBFs) offer a viable alternative to traditional primary clarifiers with the potential to reduce capital and operating costs as well as improve energy efficiency and recovery. Recent studies have shown that in comparison to sludge from primary clarifiers, sludge collected from RBFs have a greater volatile solids fraction and a comparable biochemical methane potential, making them an attractive option for feeding anaerobic digesters and enabling oxygen savings in downstream processes. RBF systems operate by separating suspended particulate matter from influent wastewater using a fine screen filter operating on the principles of sieving and cake filtration. Accurate modeling of RBF systems is challenging due to the complex interaction between flow dynamics and solid separation, suggesting the use of an advanced numerical tool such as computational fluid dynamics (CFD) is appropriate. This study describes a CFD-based numerical tool for analyzing RBF systems based on experimental characterization of wastewater filtration behavior. The model is validated using full-scale test data collected at a water resource recovery facility in London, Canada. Detailed CFD results are presented to visualize the solids separation process and assess the carbon diversion potential of RBFs.

Rapid Transfer Alignment Using Integrated Navigation System as Reference

Traditional transfer alignment must use a pure Inertial Navigation System (INS) as the reference, because using the integrated navigation system as the reference would disrupt the transfer alignment process and lead to the divergence of the fine alignment filter. But there are some cases require the cooperation between the master INS and slave INS for long time duration, such as mapping. To guarantee the accuracy of the master INS, integrated navigation feedback is needed. So, transfer alignment technique using the integrated navigation system as the reference is required. Taking the error of master INS into account, a transfer alignment attitude error in the body frame was defined, which makes the transfer alignment attitude error free from the impact of integrated navigation feedback corrections. Then, its error equations were developed and a Kalman filter was designed based on it. Finally, a transfer alignment simulation using a GPS/INS integrated navigation system as reference was performed to validate the proposed scheme.

Development and performance evaluation of external helium purifier

Helium purification system is vital for removing gaseous and oil aerosol/oil vapour impurities in helium which can freeze and damage ultra high-speed turbo-expanders and choke fine passages of cryogenic heat exchangers or fine filters of helium refrigerators/liquefiers. An external helium purifier is designed and fabricated for purification of 10 Nm3/hr flow of impure helium with maximum N2 impurity of 1%. It consists of an evacuated super-insulated cold box, a helical coil heat exchanger with tube in tube type configuration, an LN2 bath and a charcoal adsorber maintained at LN2 temperatures. The main features of the purifier are its compactness, low LN2 consumption, ease and simplicity of charcoal regeneration. Performance evaluation of the purifier is carried out by observing the impurities (N2, moisture and hydrocarbons) in the purified helium gas at its exit. Total LN2 consumption and effectiveness of heat exchanger used for recovery of cold of outgoing helium are also evaluated.

A comparison of a fractional derivative model with an empirical model for non-linear shock waves in swelling shales

Abstract The control of drilling parameters, such as fluid pressure, mud weight, salt concentration, etc., is essential to avoid instabilities when drilling through shale sections. To investigate shale deformation, which is fundamental for deep oil drilling and hydraulic fracturing for gas extraction (“fracking”), a non-linear model of mechanical and chemo-poroelastic interactions among fluids, solutes and the solid matrix is discussed here. The two equations of this model describe the isothermal evolution of fluid pressure and solute density in a fluid-saturated porous rock. If the non-linear term in these equations is larger than the diffusive term the solutions are quick, non-linear Burgers solitary waves, which are potentially destructive for deep operations. In our study the role of diffusion in presence of these solitary waves has been also analyzed. Then, following Civan (1998) , both diffusive and shock waves are applied to fine particle filtration and their effects on the adjacent rocks. Finally, the resulting time-delayed evolution is discussed. Because time delays in simple porous media dynamics have recently been analysed using a fractional derivative approach, we insert fractional time derivatives, i.e., a type of time-average of the fluid-rock interactions, to make a tentative comparison of these two deeply different methods in our model. The delaying effects of fine particle filtration a la Civan (1998) are then compared with the time delay of the fractional derivative model; thus, the fractional derivative order for this filtration is realistically estimated. Such a comparison can be seen as a heuristic determination of “natural” time averages for fine particle related phenomena in this model.

Fate of microplastics in the marine isopod Idotea emarginata.

Plastic pollution is an emerging global threat for marine wildlife. Many species of birds, reptiles, and fishes are directly impaired by plastics as they can get entangled in ropes and drown or they can ingest plastic fragments which, in turn, may clog their stomachs and guts. Microplastics of less than 1 mm can be ingested by small invertebrates, but their fate in the digestive organs and their effects on the animals are yet not well understood. We embedded fluorescent microplastics in artificial agarose-based food and offered the food to marine isopods, Idotea emarginata. The isopods did not distinguish between food with and food without microplastics. Upon ingestion, the microplastics were present in the stomach and in the gut but not in the tubules of the midgut gland which is the principal organ of enzyme-secretion and nutrient resorption. The feces contained the same concentration of microplastics as the food which indicates that no accumulation of microplastics happens during the gut passage. Long-term bioassays of 6 weeks showed no distinct effects of continuous microplastic consumption on mortality, growth, and intermolt duration. I. emarginata are able to prevent intrusion of particles even smaller than 1 μm into the midgut gland which is facilitated by the complex structure of the stomach including a fine filter system. It separates the midgut gland tubules from the stomach and allows only the passage of fluids and chyme. Our results indicate that microplastics, as administered in the experiments, do not clog the digestive organs of isopods and do not have adverse effects on their life history parameters.

Global intravascular and local hyperoxia contrast phase-based blood oxygenation measurements

The measurement of venous cerebral blood oxygenation (Yv) has potential applications in the study of patient groups where oxygen extraction and/or metabolism are compromised. It is also useful for fMRI studies to assess the stimulus-induced changes in Yv, particularly since basal Yv partially accounts for inter-subject variation in the haemodynamic response to a stimulus. A range of MRI-based methods of measuring Yv have been developed recently. Here, we use a method based on the change in phase in the MR image arising from the field perturbation caused by deoxygenated haemoglobin in veins. We build on the existing phase based approach (Method I), where Yv is measured in a large vein (such as the superior sagittal sinus) based on the field shift inside the vein with assumptions as to the vein's shape and orientation. We demonstrate two novel modifications which address limitations of this method. The first modification (Method II), maps the actual form of the vein, rather than assume a given shape and orientation. The second modification (Method III) uses the intra and perivascular phase change in response to a known change in Yv on hyperoxia to measure normoxic Yv in smaller veins. Method III can be applied to veins whose shape, size and orientation are not accurately known, thus allowing more localised measures of venous oxygenation. Results demonstrate that the use of an overly fine spatial filter caused an overestimation in Yv for Method I, whilst the measurement of Yv using Method II was less sensitive to this bias, giving Yv=0.62±0.03. Method III was applied to mapping of Yv in local veins across the brain, yielding a distribution of values with a mode of Yv=0.661±0.008.

Experimental Research on Fine Sand and Filter Material of Xing-Long Hydroproject Dam Foundation

The Xing-long hydro project is situated on fine sand foundation, whose seepage stability is a vital factor to the safety of the buildings. By means of field sampling, seepage deformation test and filter test to fine sand and filter material, the seepage deformation character of fine sand and filter material are studied. The seepage failure gradient of fine sand is very low under natural condition, its seepage stability should be satisfied under the protection of filter materials, but the protective capability of natural filter material is limited, it is suggested that the filter material be optimized by getting rid of the particles less than 0.5mm.

Repurposing Reelin: The new role of radial glia, Reelin and Notch in motor neuron migration

The role of Reelin during cerebral cortical neuron migration has long been studied, but the Reelin signaling pathway and its possible interactions are just beginning to be unraveled. Reelin is not only important in cerebral cortical migration, but has recently been shown to interact with the Notch signaling pathway and to be critical for radial glial cell number and morphology. Lee and Song (2013) show a new Notch- and Reelin-dependent role for radial glia in the mouse spinal cord: to act as a fine filter that allows somatic motor neuron axons but not cell bodies to traverse out of the CNS. Here, the types of neuronal migration are discussed, focusing on motor neurons and cues for proper localization. The interaction of Reelin signaling with the Notch pathway is reviewed, which dictates the proper formation of radial glia in the spinal cord in order to prevent ectopic motor neuron migration (Lee and Song, 2013). Future studies may reveal novel interactions and further insights as to how Reelin functions throughout the developing nervous system.

Towards a Non-linear Theory for Induced Seismicity in Shales

We analyze the pore transmission of fluid pressure p and solute density ρ in porous rocks. To investigate shale deformation, fundamental for deep oil drilling and for gas extraction (“fracking”), a non-linear model of mechanic and chemo-poroelastic interactions among fluid, solute and the solid matrix is discussed. The solutions of the model are quick non-linear Burger's solitary waves, potentially destructive for deep operations. Following Civan [2], diffusive and shock waves are applied to fine particles filtration. Then the delaying effects of fine particles filtration is compared with fractional model time delay and the fractional order parameter can be realistically estimate.

Electrospun flexible self-standing γ-alumina fibrous membranes and their potential as high-efficiency fine particulate filtration media

Flexible self-standing γ-alumina fibrous membranes with high-efficiency filtration of sub-micron aerosols have been fabricated by the electrospinning method.

To Compare and Evaluate the Sealing Ability of Root Canal Sealer with and without Triple Antibiotic Paste using Ultraviolet-visible Spectrophotometric Analysis

ABSTRACT Purpose The aim of current study was to compare and eva- luate the sealing ability of root canal sealer with and without triple antibiotic paste. Materials and methods Fifty extracted human single rooted teeth were selected and each test group had 25 teeth. The teeth were decoronated and then prepared with protaper rotary files till the no F2 in conjunction with 17% EDTA lubrication and 2 ml of 5.25% sodium hypochlorite irrigation. The teeth in group I were obturated using the zinc oxide sealer mixed with triple antibiotic paste and the teeth in group II were obturated using the zinc oxide sealer alone and then nail varnish was applied leaving the apical 3 mm of root exposed. The apical third was then immersed in 5 ml of 2% methylene blue dye in 15 ml screw capped bottle for 72 hours. The varnish was removed and the teeth were subsequently immersed in 35% nitric acid and kept again for 72 hours in a centrifugal tube. After the teeth were completely dissolved the solution was then filtered with a fine grit filter paper and centrifuged at 2000 rpm for 1 minute. The collected solution was then subjected to spectrophotometric analysis. The data was evaluated statistically by Mann-Whitney U-test. Results The results showed significant differences (p < 0.05) between the sealing ability of two groups evaluated. Conclusion Present study suggests that addition of triple anti-biotic paste to the sealer increased its sealing ability, reduced the microleakage and also imparts the antimicrobial property to the sealer. How to cite this article Shori DD, Shenoi PR, Dhote SP, Makade CS, Gunwal MK, Paralikar AV. To Compare and Eva- luate the Sealing Ability of Root Canal Sealer with and without Triple Antibiotic Paste using Ultraviolet-visible Spectrophoto- metric Analysis. Int J Prosthodont Restor Dent 2014;4(2):48-51.

Hierarchically structured polysulfone/titania fibrous membranes with enhanced air filtration performance

Hierarchically structured, superhydrophobic filter medium exhibiting robust filtration performance to airborne particulate were prepared by a facile deposition of electrospun polysulfone/titania nanoparticles (PSU/TiO2 NPs) on a conventional nonwoven substrate. The air permeability, tensile strength and abrasion resistance of pristine PSU fibrous membranes could be finely controlled by regulating the solvent composition and number ratios of jets. By employing the TiO2 NPs incorporation, the pristine PSU fibers were endowed with promising superhydrophobicity with a water contact angle of up to 152°. The quantitative hierarchical roughness analysis using N2 adsorption method has confirmed the major contribution of TiO2 NPs on enhancing the porous structure and surface fractal features with irregular rough structure. Filtration performance studies have revealed that the filtration efficiency and pressure drop of resultant hybrid membranes could be manipulated by tuning the surface composition as well as the hierarchical structures. Furthermore, the as-prepared PSU/TiO2-5 membrane exhibited improved filtration efficiency (99.997%) and pressure drop (45.3Pa) compared with pristine PSU membrane, which would make them a promising media for fine particle filtration, and a new insight was also provided into the design and development of high performance filter medium based on hierarchical structured fibers.

Effect of Melt Cleanliness on the Mechanical Properties and Microstructure on AZ91E Mg Alloy Castings

The current study examines various filter configurations, argon bubbling, and degasser addition to improve melt cleanliness of AZ91E permanent mold castings. The unfiltered castings had an average yield strength, ultimate tensile strength, and elongation of 93.3, 153.3 MPa, and 2.2% respectively. Using a fine mesh filter within the well of the mold, the ultimate tensile strength and elongation increased by 9 and 41%, respectively, compared to the unfiltered samples. A combination of a fine filter and argon bubbling resulted in an average increase in ultimate tensile strength and elongation of 29 and 123%, respectively, that matched the performance of the C2Cl6-based degassed castings with 95.8, 194.3, and 4.9% for yield strength, ultimate tensile strength, and elongation, respectively. The addition of the C2Cl6-based degasser released harmful vapors that can be avoided using the fine filter with argon bubbling. In all cases, the removal of MgO-based inclusions improved mechanical properties.

Removal of Fine and Ultrafine Particles From Air by Microelectrostatic Precipitation

Particles with dimensions less than 2.5 μm (PM2.5) have been identified as being potentially hazardous to human health. The electrostatic precipitation process, which is mainly used in industrial applications, displays a drop in the precipitation efficiency for particles in the range 0.1-1 μm. This paper is focused on the development of an impulsive microelectrostatic precipitation ( μ-ESP) technology for indoor air cleaning applications. Short (microsecond) high-voltage impulses are used in this technology, which allows the magnitude of the electric field that particles experience to be increased without complete spark breakdown occurring and also reduces the energy consumption compared to that of dc-energized systems. The charging process of particles in the impulsive electric field used in the reactor has been analyzed. Ambient laboratory air and air-diluted cigarette smoke, which contain a significant proportion of PM2.5 particles, were used in the precipitation tests. In order to optimize performance for the μ-ESP process, different energization modes of the developed precipitation reactor were studied: dc energization, impulsive energization, and their combination. It has been shown that combined dc and impulsive energization of the two stage μ-ESP reactor produces the maximum precipitation effect. In both cases, ambient laboratory air and diluted smoke, 100% precipitation efficiency has been achieved for fine (250 nm and above) particles; in the tests with diluted smoke, a fine mesh filter was incorporated in the precipitation system to achieve this level of performance.

Study on Integrated System of SCR and Muffler for Heavy-Duty Diesel Vehicle

SCR (Selective Catalytic Reduction) is widely used as a good solution of reducing NOx emissions. For NOx emissions and exhaust noise for heavy-duty diesel vehicles, the paper studied the acoustic performance for the integrated system of SCR and muffler. By analyzing the action of the perforated pipe, the exhaust pressure loss and the impact on the performance of the integrated system, the integrated system was developed for heavy-duty diesel vehicles to solve the technical problem on the integration and performance optimization for the SCR system and muffler structure. Extrusion-type vanadium-based catalyst replaces the current coated-type catalysts, and improves the reduction efficiency. The two-stage rough and fine filter and the heating device for the urea pump are designed to increase the adaptability of the SCR system. The research shows that through the structural improvements, the exhaust noise is reduced by 28.5dB.