Thickness Of Filter Layer Research Articles

Preparation of Alumina Membrane Filters with Framework Structures by Al Anodization.

Alumina membrane filters consisting of a thin filter layer (200-700 nm in thickness) supported by a framework (30-100 μm in thickness) were fabricated on the basis of the anodization of an Al substrate. The solution permeability of alumina membrane filters with tubular pores of uniform size and shape varies with membrane thickness; therefore, membrane filters with a filter layer thickness of less than 1 μm showed high solution permeability. Although the filter layer is thin, it is reinforced by a thick framework, enabling the fabrication of large freestanding membrane filters (2.5 × 2 cm2 in size). The pore size of the anodic porous alumina formed by the anodization of Al can be controlled in the range from 10 nm to ca. 2 μm by varying the preparation conditions. The alumina membrane obtained by this method is therefore useful as a membrane filter that can efficiently separate particles of various sizes, including microplastics, viruses, and bacteria. This method enables the fabrication of membrane filters with uniform pore size, high solution permeability, and sufficient mechanical strength for handling as freestanding membranes, which have been difficult to achieve with the reported preparation processes for membrane filters. The obtained membrane filters with frameworks can be applied to efficient microfiltration.

Functionalized waterworks sludge particles as column packing materials for simultaneous Cr (Ⅵ) removal and oil separation

Highly efficient and low-cost treatment of waterworks sludge and oil-containing Cr (Ⅵ) wastewater in one way is a challenge in the field of water treatment. Herein, a waste-control-waste strategy was proposed to fabricate a functionalized waterworks sludge-based Zn–Al layer double oxides material (Zn–Al LDOs/WS) for simultaneously separating Cr (Ⅵ) and oil. During the column separation process, due to the superhydrophilic/underwater superoleophobicity of Zn–Al LDOs/WS and the memory effect of LDHs, Cr (Ⅵ) will be stabled in the filter layer by electrostatic attraction and surface complexation between the Zn–Al LDHs/WS and Cr (Ⅵ), and the small oil droplets will coalesce into big oil droplets that be blocked in the separation column, thus achieving simultaneous separation. The Zn–Al LDOs/WS with hierarchical porous structure exhibit excellent simultaneous separation efficiency for Cr (Ⅵ) (99.69%) and oil (99.24%), and high separation flux (1063 L m−2 h−1). In addition, the separation efficiency and flux can be flexibly controlled by adjusting the filter layer thickness. The Zn–Al LDOs/WS also display strong acid and alkali resistance (pH 1–11), wide applicability range of initial Cr (Ⅵ) concentration (5–200 mg/L) and outstanding anti-interfering ion ability (Cl−, HCO3−, SO42−, NO3−, H2PO4−, CO32− and F−) in Cr (Ⅵ) and oil separation. Therefore, this work can not only improve treatment efficiency and save costs through simultaneous separation, effectively treat solid waste and complex wastewater, but also provide a theoretical basis for the design and application of functional materials derived from waste sludge.

Improved design of metal fiber filter materials: Experiment and theory

After a fire accident in a spent fuel reprocessing site of a nuclear power plant, the radioactive aerosol produced by the combustion is one of the main objects of accident control. Because metal fiber has good high temperature and radiation resistance, it is the preferred material for nuclear-grade filters. Taking nuclear grade filter's requirements as the evaluation index, this paper optimizes the design of metal fiber structure parameters. Under the currently limited technology, the best structural parameters are obtained by changing the fiber's basic weight and thickness of the filter layer. In addition, a protective layer and a structural layer are added on both sides to avoid damage to the filter layer during pleating and experimentation. The results show that the resistance caused by the protective layer is small, but it can improve the fiber efficiency to a certain extent, while the structural layer has little effect on the fiber performance. The optimal fiber structure parameters to meet the requirements of nuclear-grade filters are: the thickness of the fiber filter layer is 0.5 mm, and the basic weight is 950 g/m2. This work can provide a reference for the application of metal fibers to nuclear grade filters.

NaClO-based rapid sand filter in treating manganese-containing surface water: Fast ripening and mechanism

Recently, seasonal manganese contamination in the surface water is capturing ever-increasing attention and has posed significant challenges to the safety of water supply in the conventional drinking water treatment plants. This study aimed to develop new strategies to enhance the manganese removal by the sand filter. The synergistic effects of filter material type, filter layer thickness, filtration rate, and NaClO addition on the manganese removal performance, were systematically investigated. The results indicated that modified zeolite exerted the highest adsorption capacity (5.200 mg/g) for manganese. Introducing the NaClO oxidation would effectively improve the manganese removal efficiency (from 32 % to 97 %) by the modified zeolite filter compared to the control system at the filtration rate of 8 m/h, owing to the fast formation of catalytic oxidation capability. Accordingly, the effective layer thickness of modified zeolite can be shortened from 100 cm to 10–20 cm to engineer a double-layer filter consisting of both a thin modified zeolite layer and a thick natural quartz sand layer. Besides, NaClO involvement would neutralize the adverse effects of manganese removal caused by the filtration rate increase, and facilitate the formation of auto-catalytic manganese oxides (MnOx) with rough, heterogeneous, and porous surface morphology, as well as numerous tremella-like and sponge-type structures, which was related to the fast removal of manganese. These findings are full of significance in developing simple, practical, and cost-effective strategies for seasonal manganese contamination.

Experimental and Numerical Investigations of Using Nanoparticles in Groundwater Remediation

The efficiency of using zeolite nano-clay and silica sand in removing iron from groundwater is investigated experimentally as an application of in situ remediation technique using permeable reactive barrier (PRB). In the first stage of the study batch experiments were conducted on coarse silica sand and fine silica gravel to determine their iron removal efficiency from contaminated water. The results showed that the removal efficiency was about 51.90% for coarse silica sand while fine silica gravel failed to reduce the iron concentration in water. A mix of zeolite nano-clay and coarse silica sand with a ratio of 1:30 was tested. It was found that iron removal efficiency significantly increases to about 99.70%. The linear adsorption isotherm was found to be the most representative for the adsorption of iron onto coarse silica sand and the mix of nano-clay and coarse silica sand with distribution coefficients equal 0.0009 and 0.001, respectively. In the second stage a glass sand tank with coarse silica sand and a mix of zeolite nano-clay and coarse silica PRBs was constructed. The sand tank was used to investigate the effect of sampling time, head difference, iron concentration, nano-clay dosage, and thickness of permeable reactive barrier on the iron removal efficiency. The results indicated that increasing iron concentration and head difference decreases iron removal efficiency. The mix of zeolite nano-clay and coarse silica sand improves iron removal efficiency. Furthermore, increasing nano-clay dosage slightly increases the removal efficiency. However, increasing the thickness of filter layer (i.e., PRB) significantly improves the removal efficiency. Finally, the experimental model data were used to test the capability of a numerical contaminant transport model to predict the removal efficiency. The MT3DMS numerical model included within the Groundwater Modeling System (GMS) was used along with the different experimental data to obtain reaction rate values as calibration parameters for linear isotherm. Reaction rates that yield modeling results matching experimental data were obtained.

Numerical algorithm for the problem of the technological process of filtering low-concentrated suspensions

The paper presents a mathematical model in the form of a second-order nonlinear differential equation with initial and boundary conditions and a numerical method for solving the problem based on the finite-difference method of the technological process of filtration of low-concentration suspensions to determine the ranges of variation of the ion-exchange filter parameters, as well as the results of computational experiments. When developing a mathematical model, the following main filter parameters and physico-mechanical properties of solutions (liquids) were taken into account: filtration rate, rate of sedimentation of gel particles on the pores of the filter, filter porosity, filter layer thickness, kinetic coefficient, dynamic viscosity coefficient and outlet concentration of the suspension. The developed mathematical model and a numerical solution method allow determining the deposition rate of gel particles in the pores of the filter, the outlet concentration of the solution and changes in the concentration of the driving solution of the ion-exchange filter.

Experimental study on filtration effect of oilfield sewage based on new polyurethane modified materials.

In the process of oilfield wastewater treatment, the polymer-modified materials with special wettability have been recognized by many scholars for their high filtration efficiency and good adsorption effect. In this paper, we used micro-computed tomography scanning and infrared scanning technology to further explore the internal structure and surface chemistry of polyurethane modified materials and then established an experimental platform for the filtration performance of polyurethane modified materials. The change of suspended solids concentration and oil content in the sewage was tested under different filtration rate, filter layer thickness, and water quality. The results showed that the porosity of the filter material and the oil-absorbing material was 65.85% and 56.03% respectively, and the difference in the number of oxygen-containing functional groups on the surface of these two materials indicated different adsorption force for sewage impurities. And the polyurethane modified materials had good filtration performance. Through these experiments, we demonstrated that the quality of water filtrated by the polyurethane modified materials met the requirements of the 'National Comprehensive Wastewater Discharge Standards', and the filtration efficiency for suspended particles and oils in oily sewage was higher than 80%. These materials have important practical significance for the harmless treatment of oily sewage.

An Analysis of Optimum Thickness of Inverted Filter Layer Made by Manufactured Sand

The soil stability problem caused by seepage is a hot issue in geotechnical engineering, which is widely existed in natural and artificial slope, embankment, earth-rock dam and other projects. The traditional seepage calculation only considers the saturated seepage, ignoring the unsaturated seepage, and in the design of the filter layer, the thickness of the filter layer is mainly determined by experience. This study, for above problems, finite element numerical simulation method was used to simulate different thickness of filter layer, and seepage analysis in the unsaturated zone was carried out and obtained that 0.8m was the optimal thickness of filter layer in the calculation example; due to the siphon effect of matric suction, water flow also exists in the unsaturated area, and the infiltration line is not the uppermost line in the flow network; when the free water is a little lower than the height of the corewall, it will increase the seepage flow on the corewall of the dam, intensify the seepage contact and erosion, cause damage to the dam body.

Multi-Layer Filters: Adsorption and Filtration Mechanisms for Improved Separation.

Filters made of cellulose fiber and perlite particles were prepared using a wet laying papermaking technique. Polyamide-amine-epichlorohydrin (PAE) was added to provide wet strength. Filters were prepared at two different total basis weights of 200 and 400 grams per square meter (gsm). Single and multi-layered filters were structured for each total basis weights. The effect of total basis weights and multi-layered structure on methylene blue adsorption and silicon dioxide (SiO2) particle filtration was investigated. Methylene blue adsorption was performed in two modes: constant pressure and constant flow rate. In both operation modes, the adsorption capacity of multi-layered filters was significantly higher (16–100%) than for single-layer filters at the same overall weight. The effect of layer separation was also characterized using polypropylene separators and tested under constant flow rate operation. Separators provided more effective methylene blue adsorption by generating a well-distributed flow. Filtration performance was quantified with 0.5 μm silicon dioxide particles under constant pressure conditions; this is to mimic bacteria rejection. Filtration capability of SiO2 particles was reduced slightly (12%) with decreasing individual filter layer thickness regardless of the multi-layered structure. Filtering polyethylene glycol (PEG) molecules with two different molecular weights was performed; however, no rejection was recorded. The filter internal pore structure was visualized by 3D-X ray computed tomography and the void fraction was quantified. 400 gsm single layer presented areas of low fiber density forming pores, while the pore volume decreased for thinner filter layers.

Effect of filter layer thickness on the filtration characteristics of dual layer granular beds

We herein report our investigation into the effect of the filter layer thickness on the filtration performance of dual layer granular bed filters using an experimental granular bed filter with an inner diameter of 100 mm and employing fly ash as the example dust. It was found that increasing the thickness of the upper filter layer from 180 to 280 mm reduced the average outlet dust concentration of the dual layer granular bed from 8.69 to 6.57 mg/m3, in addition to prolonging the time between regeneration cycles from 43.3 to 56 min, and increasing the pressure drop across the bed from 1873 to 1978 Pa. Furthermore, increasing the thickness of the lower filter layer from 45 to 85 mm reduced the average outlet dust concentration of the dual layer granular bed from 8.69 to 3.94 mg/m3 and extended the time between regeneration cycles from 43.3 to 59 min. However, this also resulted in an increased pressure drop across the filter from 1935 to 3077 Pa. These results indicated that an increase in the thickness of the upper filter layer reduced outlet dust concentrations and extended the regeneration cycles, without having a significant impact on the total pressure drop across the dual layer granular bed. Although an increase in the thickness of the lower filter layer significantly reduced outlet dust concentrations, the pressure drop across the dual layer granular bed filter was greatly increased in this case.

Optimal Selective Arbitrary-Spaced Filters Optimization Using GA Synthesis in One-Dimensional Silicon Photonic Crystal

The optimization process is a necessary step in the design of optimal optical devices with high performances. In this paper, optimization of unidirectional photonic crystal selective arbitrary-spaced filters based on silicon Material Si with large refractive index (n = 3.5) are achieved based on the genetic algorithm technique. The photonic crystal transmission synthesis is obtained by acting on the layer widths. Genetic algorithm is employed in order to reduce the quadratic error between the desired Gaussian function defined in advance and the synthesized power transmission spectra to obtain a desired curve and get the optimal filter layer thickness. As a result, eight filters have been synthesized around respectively the wavelengths: 1.1, 1.2, 1.3, 1.4, 1.55, 1.65, 1.75 and 1.95 μm with excellent selectivity and rejection less than 18% with a transmitted bandwidth of about 0.05 μm where a transmission of about 95% is recorded at the desired wavelengths.

Reduction of bacteria and somatic coliphages in constructed wetlands for the treatment of combined sewer overflow (retention soil filters).

Combined sewer overflows (CSOs) introduce numerous pathogens from fecal contamination, such as bacteria and viruses, into surface waters, thus endangering human health. In Germany, retention soil filters (RSFs) treat CSOs at sensitive discharge points and can contribute to reducing these hygienically relevant microorganisms. In this study, we evaluated the extent of how dry period, series connection and filter layer thickness influence the reduction efficiency of RSFs for Escherichia coli (E. coli), intestinal enterococci (I. E.) and somatic coliphages. To accomplish this, we had four pilot scale RSFs built on a test field at the wastewater treatment plant Aachen-Soers. While two filters were replicates, the other two filters were installed in a series connection. Moreover, one filter had a thinner filtration layer than the other three. Between April 2015 and December 2016, the RSFs were loaded in 37 trials with pre-conditioned CSO after dry periods ranging from 4 to 40 days. During 17 trials, samples for microbial analysis were taken and analyzed. The series connection of two filters showed that the removal increases when two systems with a filter layer of the same height are operated in series. Since the microorganisms are exposed twice to the environmental conditions on the filter surface and in the upper filter layers, there is a greater chance for abiotic adsorption increase. The same effect could be shown when filters with different depths were compared: the removal efficiency increases as filter thickness increases. This study provides new evidence that regardless of seasonal effects and dry period, RSFs can improve hygienic situation significantly.

UTILIZATION OF CORN RESIDUES FOR WATER FILTRATION AT FISH TANKS

Filtration has been widely used in re-circulating aquaculture system to remove waste. However, the study of some agricultural residues (corn) usage as the filter medium has not yet been studied. Therefore, the aim of this study is to construct a filter made from inexpensive and readily available corn residues and to analyze its effectiveness in controlling suspended solids that directly impact health of fish through abrasion of gill tissues or indirectly through water quality deterioration. The performance evaluation procedure was carried out in an aquaculture system with production in glass tanks located indoor in laboratory at Faculty of Agriculture, Damietta University, Egypt. The evaluation included three concentrations of total suspended solids (450, 900 and 1350 mg/l); four residues particle size distribution (3.35, 9.53, 12.7 mm and ascending order to mentioned sizes from bottom to top); and four thicknesses of filter layer (9, 21, 33 and 45 cm). The effectiveness of this filter was measured by determining filter efficiency (ηf), % and filtration rate (FR), ml/min. It was observed that the maximum value of (ηf), % was achieved at 450 mg/l concentration of total suspended solids, ascending order to sizes from bottom to top and 45 cm thickness of filtration layer. The maximum value of filtration rate was achieved at 450 mg/l concentration of total suspended solids, 12.7 mm particle size distribution and 9 cm thickness of filter layer. Results indicated that this filter is efficient enough to remove suspended solids. Therefore, this milled corn residues filter can be used in aquaculture systems for Nile tilapia, Oreochromis niloticus culture system.

Research on the Virtual Prototype of Multifunction Filter Material Detection Device

This paper introduces the characteristics and working principle of multifunctional filter material detection device, The design of detection device filter, Can be assembled and disassembled quickly, By the combination of different height of the supporting cylinder, Can adapt to the changes of different thickness of Filter layer, Device can realize the performance of filter material under different conditions, The application of a detection scheme is illustrated by an example. Based on the way of parametric design with SolidWorks, Reasonable modeling ideas are put forward, Combined with the instance, Completed the multifunctional filter material detection device prototype of virtual design, the method can effectively improve design efficiency, For the similar product design provides a new way of thinking

Design Method for Highway Underground Trench Filter Layer in Loess Donga

Filter layer is directly related to underground trench drainage, and the current design criterion for filter layer is relatively coarse, the classification of soil is not considered, filter layer thickness and the uniformity of filter material are not required, and so the current design criterion can not meet the needs of underground trench design of loess donga. Aimed at underground trench characteristic of loess donga, based on subgrade functional mode, this paper puts forward equivalent aggregate size , evenness control standards, the number of filter layers and thickness determination principle.