A Cleanable Self-Assembled Nano-SiO2/(PTFE/PEI)n/PPS Composite Filter Medium for High-Efficiency Fine Particulate Filtration

A silicon dioxide/polytetrafluoroethylene/polyethyleneimine/polyphenylene sulfide (SiO2/PTFE/PEI/PPS) composite filter medium with three-dimensional network structures was fabricated by using PPS nonwoven as the substrate which was widely employed as a cleanable filter medium. The PTFE/PEI bilayers were firstly coated on the surfaces of the PPS fibers through the layer-by-layer self-assembly technique ten times, followed by the deposition of SiO2 nanoparticles, yielding the SiO2/(PTFE/PEI)10/PPS composite material. The contents of the PTFE component were easily controlled by adjusting the number of self-assembled PTFE/PEI bilayers. As compared with the pure PPS nonwoven, the obtained SiO2/(PTFE/PEI)10/PPS composite material exhibits better mechanical properties and enhanced wear, oxidation and heat resistance. When employed as a filter material, the SiO2/(PTFE/PEI)10/PPS composite filter medium exhibited excellent filtration performance for fine particulate. The PM2.5 (particulate matter less than 2.5 μm) filtration efficiency reached up to 99.55%. The superior filtration efficiency possessed by the SiO2/(PTFE/PEI)10/PPS composite filter medium was due to the uniformly modified PTFE layers, which played a dual role in fine particulate filtration. On the one hand, the PTFE layers not only increase the specific surface area and pore volume of the composite filter material but also narrow the spaces between the fibers, which were conducive to forming the dust cake quickly, resulting in intercepting the fine particles more efficiently than the pure PPS filter medium. On the other hand, the PTFE layers have low surface energy, which is in favor of the detachment of dust cake during pulse-jet cleaning, showing superior reusability. Thanks to the three-dimensional network structures of the SiO2/(PTFE/PEI)10/PPS composite filter medium, the pressure drop during filtration was low.

Mathematical Modeling of Suspension Filtration on a Rapid Filter at an Unregulated Rate

Mathematical modeling of detachable filtration in the split filter flow mode was carried out using exact and approximate analytical methods. An engineering technique has been developed to determine the duration of filter cycles, based on quality, economic and technical criteria. Determination of rational filter medium height was considered for two materials differed significantly by economic indexes.

Identification of Deposited Oil Structures on Thin Porous Oil Mist Filter Media Applying µ-CT Imaging Technique

The identification of microscale oil structures formed from deposited oil droplets on the filter front face of a coalescence filter medium is essential to understand the initial state of the coalescence filtration process. Using µ-CT imaging and a deep learning tool for segmentation, this work presents a novel approach to visualize and identify deposited oil structures as oil droplets on fibers or oil sails between adjacent fibers of different sizes, shapes and orientations. Furthermore, the local and global porosity, saturation and fiber ratios of different fiber material of the oleophilic filter medium was compared and evaluated. Especially the local and global porosity of the filter material showed great accordance. Local and global saturation as well as the fiber ratios on local and global scale had noticeable differences which can mainly be attributed to the small field of view of the µ-CT scan (350 µm on 250 µm) or the minimal resolution of approximately 1 µm. Finally, fiber diameters of the investigated filter material were analyzed, showing a good agreement with the manufacturer’s specifications. The analytical approach to visualize and analyze the deposited oil structures was the main emphasis of this work.

A critical review on cleanroom filtration

Purpose Cleanrooms are highly controlled enclosed rooms where air quality is monitored and ensured to have less contamination according to standard cleanliness level. Air filters are used to optimize indoor air quality and remove air pollutants. Filter media and filtering system are decided as per requirement. Depth filter media are mostly used in cleanroom filtrations. This paper aims to present a comprehensive review of the evolution of cleanroom filter media. It evaluates the advantages and disadvantages of air filter media. It is also studied which air filters have additional properties such as anti-microbial properties, anti-odour properties and chemical absorbent. Development and innovation of air filters and filtration techniques are necessary to improve the performance via the synergistic effect and it can be a possible avenue of future research. Design/methodology/approach This paper aims to drive the future of air filter research and development in achieving high-performance filtration with high filtration efficiency, low operational cost and high durability. Air pollutants are classified into three types: suspended particles, volatile organic pollutants and microorganisms. Technologies involved in purification are filtration, water washing purification, electrostatic precipitation and anion technology. They purify the air by running it through a filter medium that traps dust, hair, pet fur and debris. As air passes through the filter media, they function as a sieve, capturing particles. The fibres in the filter medium provide a winding path for airflow. There are different types of air filters such as the high-efficiency particulate air filter, fibreglass air filter and ultra-low particulate air filter. Findings Emerging filtration technologies and filters such as nanofibres, filters with polytetrafluoroethylene membrane are likely to become prevalent over the coming years globally. The introduction of indoor air filtration with thermal comfort can be a possible avenue of future research along with expanding indoor environment monitoring and improving air quality predictions. New air filters and filtration technologies having better performance with low cost and high durability must be developed which can restrict multiple types of pollutants at the same time. Originality/value The systematic literature review approach used in this paper highlights the emerging trends and issues in cleanroom filtration in a structured and thematic manner, enabling future work to progress as it will continue to develop and evolve.

The effectiveness of filters on catfish Clarias gariepinus fry performance in the aquaponic system

This study aimed to determine the effectiveness of filters on the growth performances of catfish fry (Clarias gariepinus) in the aquaponic system. The study was conducted in the Ciparanje Green House, Faculty of Fisheries and Marine Sciences, Universitas Padjadjaran, Jatinangor. A completely randomized design with four treatments and three replications was applied, namely treatment A: Water circulation using bioball filter medium, B: Water circulation using water spinach filter medium, C: Water circulation using bioball and water spinach filter media, and D: Water circulation using sponge filter medium (control). The container used for the maintenance was a fiber tank at 70 cm × 70 cm × 70 cm size filled with 257 L water and a stocking density of 15 fish/fiber. The parameters observed were survival rate, growth, feed conversion, and water quality. The results showed that the use of biological filter using water spinach produced the best growth performance of catfish. The best survival rate was also obtained by using water spinach filter (100%) with the absolute growth of 98.32 ± 15.6 g. The water quality an aquaponic system with water spinach filter supported the growth performance of catfish fry. Keywords: absolute growth, aquaponic, Clarias gariepinus, filters. ABSTRAK Penelitian ini bertujuan untuk menguji efektivitas filter terhadap performa pertumbuhan benih ikan lele Clarias gariepinus dalam sistem akuaponik. Penelitian dilakukan di Laboratorium Rumah Kaca Ciparanje, Fakultas Perikanan dan Ilmu Kelautan, Universitas Padjadjaran, Jatinangor. Metode penelitian adalah rancangan acak lengkap dengan empat perlakuan dan tiga ulangan, yaitu perlakuan A: sirkulasi menggunakan media filter bioball, B: Sirkulasi menggunakan media filter bayam air, C: Sirkulasi menggunakan media filter bioball dan tanaman kangkung, dan D : Sirkulasi menggunakan media spons (kontrol). Wadah yang digunakan untuk pemeliharaan bak fiber dengan ukuran 70 cm × 70 cm × 70 cm diisi dengan air sebanyak 257 L dengan padat tebar 15 ekor / bak. Parameter yang diamati adalah kelangsungan hidup, pertumbuhan ikan, konversi pakan dan kualitas air. Hasil penelitian menunjukkan bahwa penggunaan filter biologis menggunakan tanaman kangkung menghasilkan performa pertumbuhan ikan lele yang terbaik. Tingkat kelangsungan hidup terbaik juga ditunjukkan oleh pelakuran dengan filter berupa tanaman kankung (100%) dan pertumbuhan mutlak 98,32 ± 15,6 g. Kualitas air sistem akuaponik dengan filter tanaman kangkung mendukung performa pertumbuhan benih ikan lele.

A Coupled CFD-DEM Model for Resolved Simulation of Filter Cake Formation during Solid-Liquid Separation

In cake filtration processes, where particles in a suspension are separated by forming a filter cake on the filter medium, the resistances of filter cake and filter medium cause a specific pressure drop which consequently defines the process energy effort. The micromechanics of the filter cake formation (interactions between particles, fluid, other particles and filter medium) must be considered to describe pore clogging, filter cake growth and consolidation correctly. A precise 3D modeling approach to describe these effects is the resolved coupling of the Computational Fluid Dynamics with the Discrete Element Method (CFD-DEM). This work focuses on the development and validation of a CFD-DEM model, which is capable to predict the filter cake formation during solid-liquid separation accurately. The model uses the Lattice-Boltzmann Method (LBM) to directly solve the flow equations in the CFD part of the coupling and the DEM for the calculation of particle interactions. The developed model enables the 4-way coupling to consider particle-fluid and particle-particle interactions. The results of this work are presented in two steps. First, the developed model is validated with an empirical model of the single particle settling velocity in the transition regime of the fluid-particle flow. The model is also enhanced with additional particles to determine the particle-particle influence. Second, the separation of silica glass particles from water in a pressurized housing at constant pressure is experimentally investigated. The measured filter cake, filter medium and interference resistances are in a good agreement with the results of the 3D simulations, demonstrating the applicability of the resolved CFD-DEM coupling for analyzing and optimizing cake filtration processes.

Filtration and Backwashing Studies: Obafemi Awolowo University Waterworks as A Case Study

This research centres on the study of the filtration and backwashing operations of the filtration unit of the Opa Waterworks and a detailed laboratory study of the filtration and backwashing characteristics of the filter medium being used at the treatment plant. A detailed study of the filtration unit of Opa Waterworks was undertaken with particular emphasis placed on the estimation of the volume of water used during backwashing, the backwashing procedure and the average backwashing time. Specific properties of the filter medium used in the gravity filter such as porosity, density, equivalent density, specific gravity and unhindered settling velocity were investigated in the laboratory. The backwashing properties of the filter medium was also studied using the DSF (Dynamic Shape Factor) and Sphericity models and the predicted results obtained were compared to the actual laboratory results. Based on works carried out, the volume of wash-water required for the gravity filters was estimated as 14,200 litres (14.2 m3) which is about 3.12% of the total volume of the clear water tank, with an outflow rate of 0.01 m3/s. The accuracy of the Blake – Kozeny equation in predicting head loss across a filter bed using clean water runs was investigated and found to be reasonably accurate, and the prediction errors