Ceramic Filters Research Articles

Performance Assessment of Household Water Treatment and Safe Storage in Kathmandu Valley, Nepal

Although many households in the Kathmandu Valley rely on household water treatment and safe storage (HWTS) to obtain drinking water, the safety of treated water has not been evaluated in actual usage. Therefore, we assessed the performance and maintenance of five HWTS methods used in 101 households. The choice of HWTS methods by households was primarily influenced by the raw water source, that is, jarred water users opted for boiling and groundwater users selected reverse osmosis with ultraviolet irradiation (RO-UV). While boiling and electric dispensers (ED) did not remove inorganic contaminants (ammonia nitrogen, arsenic, and manganese), ceramic candle filters (CCF) and RO-UV reduced them moderately. The HWTS methods reduced E. coli and total coliforms (TC) by 95.8 and 84.1%, respectively, but 11.8 and 69.3% of treated water samples remained positive for these two bacteria. Combined methods (CM) and RO-UV showed an inferior TC reduction compared to the simpler HWTS methods, boiling, CCF, and ED, possibly due to difficulties with regular maintenance and storage contamination. Therefore, it is recommended to choose simpler HWTS methods that meet the requirements of the household’s water sources rather than more expensive and difficult-to-maintain methods, which should be chosen only if the raw water contains high concentrations of inorganic contaminants.

Production of Clay-Based Water Filter Using Biomass of Bacillus Subtillis, Sawdust, Activated Charcoal, Periwinkle and Snail Shell as Additives

A Significant proportion of rural households lacked access to improved and safe drinking water due to chemical and microbial contamination. Point-of-use (POU) water filters made from cheap, locally available ceramic materials and additives can achieve quality water parameters. Ceramic water filters were prepared by combining clay minerals with additives. Sawdust was used as a burnout material to achieve porosity and enhance the filtration rate. Silver nitrate, charcoal, periwinkle shell, snail shell, and biomass of Bacillus Subtilis were added in different ratios. The filter was formulated with charcoal, sawdust, snail shell, and periwinkle shell to remove microbes and treat heavy metals through the adsorption process. The filters were molded and fired in a temperature range of (700oC - 900oC). Characterization of the clay mineral, physiochemical and Microbial tests were conducted on the ceramic and water. Antimicrobial test was carried out on the biomass of Bacillus subtilis. Mineralogical (XRD) and elemental analysis of the clay, snail, and periwinkle shells showed high percentage composition of serpentine (a clay crystal), plagioclase, a mixture of feldspar minerals albite (sodium aluminosilicate - NaAlSi3O8), anorthite calcium aluminosilicate- CaAl2Si2O8) and Calcium (70-97 %composition) respectively. The results showed a greater proportion of silica in the clay, suggesting the material is silicate. Filtration rate was estimated at 1.125 L/hr. The result showed the filter has 96.72%, 99.26%, and 66.67% colony removal efficiency for heterotrophic bacteria, coliform, and fungi respectively. The filter showed about 70% - 96% efficiency for the treatment of physiochemical parameters in wastewater.

Performance validation of a non-photocatalytic air purifier built by reactive adsorbent against a commercial UV-based air purifier

A portable non-photocatalytic air purifier (AP) was built by modifying a honeycomb-type ceramic (HC) filter through immobilization of a reactive adsorbent (i.e., manganese dioxide (MnO2 (1 wt%))-Universitetet i Oslo (UiO)-66-amine (NH2): namely, M-U6N). This non-photocatalytic AP system was examined for the removal of gaseous formaldehyde (FA) at room temperature (RT) in a 17 L airtight chamber. The kinetic reaction rates (RW, μmol h−1 g−1) of AP (M-U6N), when measured at 10%, 50%, 90%, and 100% of its removal, were 631, 433, 191, and 114, respectively. This non-photocatalytic AP system fully mineralized FA to CO2 and H2O through the Mars–van Krevelen (MvK) mechanism with a significantly higher (i.e., 1.6–3.3 times) kinetic reaction rate (RF, μmol h−1 filter−1) than that of its UV-based AP counterpart. As such, based on our experimental performance validation, the non-photocatalytic AP system developed in this work was demonstrated to be superior to the commercial photocatalytic AP system in the treatment of gaseous FA. The findings of this study offer practical guidelines for the fabrication of cost-effective non-photocatalytic AP systems.

Influence of filter surface roughness on the pressure drop of ceramic foam filters

The pressure drop of a ceramic foam filter is an important characteristic indicating the resistance to fluid flow through the filter. Filtration experiments have shown that filtration efficiency increases with decreasing functional pore size. However, this improvement comes at the cost of a higher pressure drop. Furthermore, trials with increased roughness of filter struts showed an improved filtration behavior. Comparing the influence of these filter properties on the filter efficiency is of high interest in terms of filtration per pressure drop. Therefore, the sensitivity of the pressure drop with respect to surface roughness needs to be known. In the study, the pressure drop of ceramic foam filters was measured for different functional pore sizes, porosities, and surface roughness in a water-based test facility at NTNU in Trondheim, Norway. The flow velocity was varied in the range of 0.6–80 cm/s, allowing the determination of the Darcy and non-Darcy permeability coefficients.

THE USE OF CERAMIC FILTERS IN THE SMELTING OF WORKPIECES FROM HEAT-RESISTANT ALLOYS

To improve the operational characteristics of gas turbine engine blades, it is necessary to use new methods of cleaning and refining metal. Melt filtration is an effective way to improve casting quality.According to the conducted analyses, it was determined that the amount of conditioned waste generated during the smelting of products reaches 27% of the mass of the spent charge, and non-conditioned waste rejected during LUMMA control is 23%. The results of the statistical analysis show that the total amount of waste generated during the smelting of gas turbine blades is, on average, 60–70% of the weight of the loaded charge.The purpose of the work is to create a new composition of the ceramic mixture for the production of high-strength filters, as well as the development of technology for the production of gas turbine parts using them.The analysis was performed on samples of heat-resistant corrosion-resistant alloy CM88Y. The alloy for research was melted from the primary charge on the UPPF-3M foundry unit. As a result of the work carried out, a new rational composition of the mixture for the manufacture of ceramics was created, which allows to increase the characteristics of strength and heat resistance. An instruction was created for the manufacture of ceramic filters at machine-building enterprises. To eliminate damage to ceramic rods in blades under the influence of thermal shock, improved systems for filtering metal in a liquid state and filling ceramic molds are proposed. Uniform temperature distribution across the cross-section of the casting also reduces the number of defective products.

Flame-sprayed alumina molten metal filters for dead-mould casting application

Ceramic foam filters are applied to remove non-metallic inclusions during steel melt filtration. The flame-spray technology can contribute to improving such filters by increasing the deposition capability of inclusions and decreasing the impairment of the filter substrate by the steel melt. This makes them suitable for application to the continuous steel casting process and foundry casting. The ball-on-three-balls test was utilized at elevated temperatures to determine the high-temperature behaviour of thermally sprayed alumina. Additionally, the flame-spray technology was used to produce carbon-free filters composed of flame-sprayed alumina by coating and burning out the Al2O3–C filter substrate during a sintering step. The B3B revealed a ductile behaviour with increasing temperature and a bending strength of 23.28 MPa at 1400 °C. After sintering at 1400 °C, the filters showed a sufficient CCS of 0.16 MPa, which allows the performance of casting tests (immersion and pouring) with molten steel at 1580 °C.

Water disinfection using durable ceramic filter coated with silver nanoparticles synthesized using actinomycetes

Contamination with pathogens degrades water quality and is a major cause of many waterborne diseases. The aim of this research is to reduce the global disease burden by presenting an efficient, durable, and low-cost ceramic filter impregnated with actinomycetes-mediated silver nanoparticles (AgNPs) for water disinfection in rural areas. This marks the first report on the simultaneous biosynthesis of AgNPs utilizing cell-free supernatants obtained from terrestrial actinomycetes. An easy and efficient method was used to impregnate AgNPs onto a ceramic filter using 3-aminopropyltriethoxysilane (APTES). The APTES linker is anchored to the ceramic surface through Si–O–Si bridges, while the terminal amino groups coordinate with AgNPs. Notably, the observed inhibition zone around the filter with AgNPs was ~ 18 mm, suggesting that the silver ions were responsible for the antibacterial activity. After 30 min of sonication, only insignificant traces of AgNPs were released from the filter, making it stable for long-term antibacterial activity when treating water. According to the laboratory simulation experiments, the untreated filter can reject about 99% of spiked bacteria, while the antibacterial efficiency of the filter coated with AgNPs was 100% due to the synergistic effect between filtration and disinfection with AgNPs. In addition, the average concentration of dissolved silver in the outlet water of the ultrafiltration system during three months was 33.7 μg/L, far below the permissible limit (100 μg/L) for drinking water. Overall, this work offers a suitable and affordable water treatment strategy for low-income, isolated, and rural societies in developing countries.

Removal of gaseous formaldehyde by portable photocatalytic air purifier equipped with bimetallic Pt@Cu-TiO2 filter

In this research, a mini-scale air purifier (AP) system was built with a series of honeycomb (HC) ceramic filters coated with 1 wt% Pt@Cu/TiO2 (AP (PCT-x), where x = 1, 2, and 3 for Pt:Cu weight ratios). The designed AP (PCT-x) photocatalytic systems were investigated for the removal of formaldehyde (FA) vapor under varying operational conditions (e.g., FA concentration (0.5–5 ppm), AP-flow rate (100–160 L/min), and UV light intensity (0.004–0.982 W)). The enhanced photocatalytic activities of AP (PCT-x) system (e.g., compared to the monometallic analogues) are suspected to reflect the synergistic role of Pt metal sites (in terms of high work function (5.93 eV) for the 111 crystal plane) in the Pt@Cu bimetallic structures and the high electronic transitions between Pt and Cu sites on the TiO2 surface. Nonetheless, their photocatalytic activities tend to decrease at higher Pt content (e.g., PCT-3 relative to PCT-2) due possibly to the formation of Pt clusters and associated shielding effect. Overall, AP (PCT-2) exhibited the highest efficacy (over five reuse cycles) to attain 100% removal of FA (0.5 ppm) within 5 min at an AP-flow rate of 160 L/min and UV light intensity of 0.982 W (quantum yield (QY) of 1.94E-04 molecules/photon and figure of merit (FOM) of 1.21E-06 L∙mol/ (mg∙ J∙h)). According to the in-situ DRIFTS analysis, Pt2@Cu metal sites were favorable to promote the transfer of photo-induced charge carriers by TiO2 so as to accelerate the oxidation reaction of FA vapor (e.g., through the generation of OH• and O2•- radicals). This study offers practical insights into the potential of controlled tuning of redox dynamics (i.e., between Pt and Cu metal sites on TiO2) in the enhancement of the photocatalytic performance for air purification system.

Development of low-temperature thermal decomposition recycling technology from photovoltaic modules to flat glass applications

The recycling method for thermal decomposition of photovoltaic modules is a recycling method that can completely remove EVA, which is a sealing material, and can neatly separate the cells and glass. However, most back sheets are made of PET, and if they are simply thermally decomposed, a large amount of complex bonded carbides (“soot”) is generated. We succeeded in suppressing the generation of soot by heating resin components such as PET and EVA, melting and dropping them into a ceramic filter supported by a catalyst, promoting the oxidation reaction, and separating the glass and the cells cleanly. It was confirmed that the thermal decomposed PV glass can be recycled into flat glass by a float glass manufacturing company.

Fluid flow analysis of the lattice-based ceramic filters in molten metal filter application

The ceramic lattice filters are ideal for various technical applications, including filtration, flow stability, and heat transfer, that could alter the transport characteristics like pressure, permeability, and velocity. The authors presented a computational study based on the fluid flow parameters for four struts-based lattice structures in this work. This study includes seven designs of four struts-based lattice structures systematically created with 30 pores per inch (PPI) and 80% porosity while varying the unit cell sizes and strut diameter. The present computational study has been carried out using the turbulent k-epsilon (k-ε) model with the chosen metal alloy, IN718. The efficacy of the lattice filters has been determined by visualizing the physical parameters like pressure drop and velocity distribution patterns inside the filters. This study concludes that the BCC and the Diamond lattice structures have outperformed the other designs. Moreover, the effects of the variation in the unit cell and strut size have been evaluated for different structures and discussed.

Low-cost ceramic filter bioreactor for treatment and reuse of residential septic tank effluent: A decentralized approach for small communities

Membrane biological reactors (MBRs) have recently become widely accepted as an advanced technology for treating domestic wastewater for improved water recovery, reuse, and recycling. The present study investigated the application of a low-cost ceramic filter bioreactor (CFBR) to treat septic tank effluent for smaller communities in Saudi Arabia (KSA). Filter fouling behavior, pollutant removal, and effluent quality were assessed under varying flux (0.2, 0.4, and 0.65 m/d) and aeration on/off cycle (60 min/60 min, 40 min/80 min, 30 min/90 min, 24 h/24 h) conditions. Operating CFBR at a flux value of 0.4 m/d ensured moderate fouling propensity, reasonable flux decline, and a higher volume of treated effluent. In the continuous aeration mode experiments, CFBR demonstrated the removal of various pollutants. Except for NO3N, CFBR effectively reduced all other pollutants of concern (BOD, COD, TSS, NH3N) in the effluent to acceptable levels meeting the water quality standards for unrestricted irrigation set by the KSA. An enhanced NO3N removal at the 24 h/24 h on/off cycle, indicating the effectiveness of cyclic aeration for promoting both nitrification/denitrification in the CFBR, with sufficient removal of other pollutants, is an original finding of the present study. Simple and cost-effective operations, high-quality effluent, and reduced energy consumption with shorter aeration duration promote the sustainability of the CFBR system for wastewater reclamation and reuse in small communities and rural settlements.

Elution and disinfection of silver and zinc nanoparticles in co-fired ceramic water filters

Ceramic water filters (CWFs) are decentralized water treatment technologies commonly used in resource-restricted geographies. Inclusion of silver nanoparticles (AgNP) assists with disinfection but can substantially increase costs. This research investigates AgNP supplementation with zinc oxide (ZnO) as a low-cost bactericide alternative. CWF disks were impregnated with varying AgNP and/or ZnO concentrations and challenged against Escherichia coli. Effluent bacteria were enumerated and monitored over 72 h while eluted metal concentrations were measured and scaled according to surface area to establish ‘pot-equivalent’ estimates (0–50 ppb Ag and 0–1200 ppb Zn). Ag addition correlated to subsequent measured release values, though Zn impregnation did not. Background Zn was thus evidently present. Meanwhile, the eluted metal concentration related to disinfection: a CWF with a pot-equivalent elution estimate of 2 ppb Ag and 156 ppb Zn achieved a Log Removal Value (LRV) of 2.0 after 60 min of filtration and 1.9 after 24 h of storage while a CWF with a pot-equivalent elution estimate of 20 ppb Ag and 376 ppb Zn achieved LRVs of 3.1 and 4.5 after the same filtration and storage times, respectively. Clay elemental composition may therefore impact filter performance more than previously considered This trend was further confirmed by batch experiments with Ag and Zn in concentrations of 0–20 ppb Ag and 0–800 ppb Zn, respectively: bacterial regrowth was only observed when Ag and Zn were each below 5 ppb and 160 ppb while 1 ppb Ag and 800 ppb Zn maintained complete disinfection for 72 h. Increased Zn concentrations thus reduced Ag required to maintain disinfection over time. Overall, it is recommended to include Zn with Ag for CWF to improve short-term and long-term disinfection efficacy and associated water safety.

An eco-friendly strategy for recovery of H2-CH4-rich syngas, benzene-rich tar and carbon nanoparticles from surgical mask waste using an updraft gasifier system

ABSTRACT The COVID-19 pandemic has created a new type of waste (surgical mask waste “WMs”) that presents a major challenge now and in the future, given the strong possibilities of similar epidemics to reoccur. In order to find an effective industrial solution to the millions of WMs produced daily, this research aims to develop a new eco-friendly strategy to convert WMs into H2-CH4-rich syngas, carbon nanoparticles (CNPs), and benzene-rich tar using an updraft gasifier system. The experiments started with the preparation of WM granules using shredding followed by granulation processes. Subsequently, the granules were processed in a lab-scale reactor with a capacity of 0.9–1 kg/h and consisted of a continuous WM feed system, a gasifier, a sampling system for syngas and tar, a ceramic filtration unit for separating the CNPs against the synthesis gas, and a burner. The gasification experiments were performed in ambient air with different air−fuel equivalence ratios (ER: 0.21, 0.25, and 0.29) and temperatures (700°C, 800°C, and 900°C) to determine the optimal conditions that yield the maximum amount of H2-CH4-rich syngas and CNPs with less impurities. The chemical composition and morphology of the obtained gasification products (syngas, tar, and CNPs) were observed using GC-FID, FTIR, and SEM. The results showed that the maximum production of syngas (4.29 ± 0.16 kg/h with HHV of 3804 kJ/kg) and CNPs (0.14 ± 0.011 kg/h) accompanied by a moderate tar rate (0.123 ± 0.009 kg/h with HHV of 41,139.88 kJ/kg) could be obtained at 900°C and ER = 0.29, while the highest H2 (16.93 ± 1.7 vol.%) and CH4 (10.44 ± 0.85 vol.%) contents in syngas product were synthesized at 900°C and ER = 0.19. Benzene and toluene were the major GC-FID compounds in the formulated tar product with abundance up to 25.6% and 11%, respectively. Meanwhile, gasification conditions of 900°C and ER = 0.24 allowed the best morphology to be formulated for spherical-shaped CNPs with a diameter of less than 200 nm.

Optimization of inorganic powder properties for manufacturing ceramic filter using binder jetting process

Optimization of inorganic powder properties for manufacturing ceramic filter using binder jetting process

Use of chalky algae in the manufacturing of clayey ceramic membranes: Microstructural and dielectric behavior for electrochemical applications

Novel ceramic membrane filters were manufactured from kaolino-illitic clays and calcareous algae (up to 20 wt.%) as porogenic agent. The produced membranes were investigated using X-ray diffraction, thermogravimetric analysis, scanning electron microscope, impedance spectroscopy, and Fourier-transform infrared spectroscopy. All of the filtration suitability, electrical properties, and dielectric behavior were assessed and interrelated to the microstructure. It was found that the original clay minerals were involved in the mineralization development while the inclusion of large pores (8–12 μm) was observed at high magnification alongside porosity increase (up to 70%) due to the addition of the bio-based pore-former. Both electric and dielectric measurements revealed that the sintering process was governed by the densification phenomenon and was accompanied with lower activation energy. The order of magnitude of the values taken by electrical impedance was close to average Mega-Ohms suggesting the suitability of the produced ceramic membranes as an electrical insulator for typical electrochemical devices. The tests of filtration have shown that the ceramic membranes produced operate normally in the microfiltration range for a period of 50 min without clogging and at pressures up to 0.12 bar. Conclusively, the developed ceramic membranes could be considered for applications in industrial wastewater treatment and electrochemical media.In addition to this, a perspective has been proposed on the improvement paths or designs for ceramic membrane filters with good performance in wastewater treatment present in some electrochemical environments as well as methods to cope with the challenges regarding the performance of such materials.

Filtration Performance of 3D-Printed Ceramic Pellets: Investigation Using CFD and Computed Tomography

This study demonstrates the potential for computer-aided engineering and additive manufacturing techniques to fabricate protective layer materials with a novel design of filtration channels. Using computational fluid dynamics (CFD) simulation for channels of various geometries, potential locations of the capture of solid dust particles in ceramic filter pellets were identified. The filter pellets were fabricated from ceramic material using laser stereolithography. The printed samples were subjected to a filtration test. The CFD simulation of the pellet channels to identify potential filtration locations, followed by a comparative assessment of the simulation results and the post-test X-ray computed tomography (CT) scan of the 3D-printed pellets, demonstrated the feasibility of CFD models for the design of filter materials. The study findings are intended for the development of innovative protective materials with filtering capabilities to be implemented in specific industrial refining applications

High-Temperature Syngas Desulfurization and Particulate Filtration by ZnO/Ceramic Filters.

Combustible gas (e.g., gasification syngas) cleaning at high temperatures can obtain further gains in energy efficiency for power generation and importantly leads to a simplified process and lower cost as a commercially viable source of clean energy. Thus, a feasibility study for high-temperature desulfurization (HTDS) and additional high-temperature particulate filtration (HTPF) of a raw syngas using ZnO sorbent-dispersed Raney CuO (ZnO/R-CuO) and ceramic filter (ZnO/CF) has been carried out. By synchrotron X-ray absorption near-edge structure (XANES) spectroscopy, mainly Zn(II) and Cu(II) are found in the ZnO/R-CuO sorbents. Both ZnO and R-CuO in the sorbents are involved in HTDS (1% H2S) at 873 K to form ZnS, Cu2S, and a small amount of CuS and reach relatively high HTDS efficiencies (82-90%). In addition, regeneration of the sulfurized sorbent by oxidation with O2 at 873 K (HTRG) for 1 h can restore ZnO and CuO for continuous and repetitive HTDS-HTRG cycles. To facilitate the HTDS engineering applications by the ZnO/R-CuO sorbents, their reaction rate constant (8.35 × 104 cm3/g/min) and activation energy (114.8 kJ/mol) at 873 K have also been determined. Furthermore, the ZnO/CF sorbent/filter can perform HTDS and additional HTPF at 873 K with very high particulate removal efficiencies (>98%). This demonstrates the feasibility for hot-syngas cleaning with a much better energy efficiency and lesser cost for cleaner power generation.

The silver paste containing ZnO-B2O3-SiO2 glass sintered at high temperature with low solid content formed high performance conductive thick film on MgTiO3 microwave ceramics

A high-temperature conductive silver slurry containing lead-free ZnO-B2O3-SiO2 glass for metallization of ceramic MgTiO3 substrate has been prepared. The ZnO-B2O3-SiO2 glass was obtained by high-temperature melting and cold extraction with a transition temperature (Tg) of 579 °C and thermal stability (∆T) of 105 °C as an inorganic bonding phase of high-temperature conductive silver paste. Then, silver paste with different glass powder content was sintered on ceramic MgTiO3 substrate between 730 °C and 930 °C in increments of 50 °C. Characterization of the prepared materials revealed that their resistivity increases with the increase in glass powder content and decreases with the increase in sintering temperature. Sintering temperature and glass content have significant effects on the resistivity and adhesion of the thick silver film. When the silver paste with a glass content of 1.1 wt% was sintered at 830 °C for 10 min, the resulting thick silver film had a low resistivity of 1.81 μΩ·cm (1.65 μΩ·cm for silver) and a good adhesive strength of 39.4 N mm−2. During the sintering process, the glass material melts and wets the silver powder, which promotes the sintering of the silver powder to form a dense network structure and improves the electrical conductivity of the silver film. In addition, the formation of ZnTiO3 by chemical reactions between the glass and the substrate was observed, which dramatically improved the bonding strength of the silver film. Therefore, lead-free silver paste containing ZnO-B2O3-SiO2 glass powder and MgTiO3 ceramics has broad development prospects in ceramic filters.

Changes in water treatment, hygiene practices, household floors, and child health in times of Covid-19: A longitudinal cross-sectional survey in Surkhet District, Nepal.

Consistent and effective practice of water treatment, sanitation, and hygiene (WASH) behaviour is an indispensable requisite for realizing health improvements among children living in low-income areas with challenging hygienic conditions. Sustainably achieving such a behaviour change is challenging but more likely to be realized during epidemics, when health threats are high and the dissemination of information on preventative measures is intense. Our study conducted cross-sectional surveys in Surkhet District Nepal, before and during the Covid-19 pandemic to assess the impact of water safety interventions and hygiene training implemented before and during the pandemic on WASH conditions and practices and to assess the association of these changes with child health. Information on WASH infrastructure, WASH behaviour, nutrition, and child health, including on parasitic infections, was obtained before and during the Covid-19 pandemic in spring 2018 and spring 2021, from 589 children aged between 6 months and 10 years and their caregivers. Data was collected through quantitative, structured face-to-face interviews, observations, health examinations of children including anthropometric measurements, analysis of children's stool, and water quality analysis. The association of changes in WASH factors with changes in child health was analysed using multivariate generalized estimating equations for repeated measures. Water safety management was significantly improved by the introduction of chlorination to piped water supply systems, which served 40% of households. In addition, the percentage of households using a ceramic water filter increased from 12.2% to 34.8%. Large and significant changes were observed in handwashing behaviour (frequency, use of soap and washing at critical times) and infrastructure: 35% of households constructed a new handwashing station. Kitchen and household hygiene also improved. An additional 22% of households improved the cleanliness of the toilet. The number of houses with a cemented floor increased by 20%. WASH changes were significantly associated with improved child health: the chlorination of piped water supply reduced odds ratios for diarrhoea (OR=0.36, 95% CI=0.15-0.88, p=0.025), respiratory difficulties (OR=0.39, 95% CI=0.16-0.92, p=0.033), fever (OR=0.42, 95% CI=0.26-0.71, p=0.001) and cough (OR=0.58, 95% CI=0.36-0.93, p=0.024), and. The frequency of handwashing with soap was associated with significantly reduced odds ratios for infections with Giardia lamblia (OR=0.68, 95% CI=0.50-0.91, p=0.011), stunting and wasting (OR=0.75, 95% CI=0.66-0.92, p=0.003) and fever (OR=0.85, 95% CI=0.75-0.96, p=0.008),. The presence of a handwashing station at baseline was associated with significantly reduced odds ratios for respiratory difficulties (OR=0.45, 95% CI=0.26-0.78, p=0.004). The construction of a handwashing station between baseline and endline was significantly associated with reduced odds ratios for pale conjunctiva (OR=0.32, 95% CI=0.17-0.60, p<0.001), which is a clinical sign of iron deficiency and anaemia, respiratory difficulties (OR=0.39, 95% CI=0.17-0.89, p=0.026) and cough (OR=0.44, 95% CI=0.26-0.76, p=0.003). Using a clean container for the transport of drinking water was significantly associated with reduced odds ratios for infections with Giardia lamblia (OR=0.39, 95% CI=0.16-0.93, p=0.033) and diarrhoea (OR=0.48, 95% CI=0.24-0.96, p=0.038). Similarly, a cemented floor in the household was significantly associated with reduced odd ratios for diarrhoea (OR=0.38, 95% CI=0.16-0.87, p=0.022) and infections with Giardia lamblia (OR=0.44, 95% CI=0.19-1.02, p=0.056). WASH training and the promotion of preventative measures during the Covid-19 pandemic supported improved water safety management and hygiene behaviour, which resulted in a reduction in infectious diseases among children in the study area.

Hydraulic Characterization of Ceramic Foam Filters Used in Aluminum Filtration.

Ceramic Foam Filters (CFF) are frequently used during the filtration of aluminum (Al) melts to produce high-quality products. In the present study, the physical and hydraulic characteristics of alumina (Al2O3)-based CFF from three different suppliers (A, B and C) have been thoroughly investigated. The filters' porosity and pore diameter, i.e., Window and Cell Feret diameters, were measured and the permeability of the different filters calculated based on pressure drop experiments. The comparison of the classification systems of CFF, i.e., Grade and PPI (Pore Per Inch) numbers, using statistical analysis of permeability and Window Feret diameter showed significant variations between the morphological and hydraulic properties of some CFFs of identical Grade and PPI numbers. Moreover, the Fanning friction factor was plotted as a function of interstitial Reynolds numbers (Rei), and laminar, transient, and turbulent flow regimes were identified. The relationship between the Fanning friction factor and the interstitial Reynolds numbers of all the filter samples investigated was processed using regression analysis, and a model equation developed to calculate the pressure drop over the CFF using the Window Feret diameter. The correlation between the experimental pressure drop values and the derived model equation indicates that empirical expressions for calculating the pressure drop over CFFs should be derived based on experimental measurements carried out at the velocity range of the application of the CFF, which is about 10 mm·s-1 for aluminum filtration.