Filter Media Research Articles

Study on preparation and application comfort of composite personal protective nanofiber filter material for mining

Miner's pneumoconios is a serious global public health problem. To further improve the application performance of individual protective materials, this paper prepared three-layered composite filter material composed of a hydrophobic external layer, a dust filter intermediate layer, and a moisture permeable internal layer, and explored the influence of composite ratio on the comprehensive performance of the filter material. The thermal comfort evaluation index system under complex working conditions environment was established. The results show that the optimal composite ratio of composite filter material is 2/6/2. This optimal composite filter material has dual-structure with high filtration efficiency of 99.9 %, low resistance of 98.7Pa, high quality factor of 0.07 and high air permeability of 364 mm/s. The construction of the wetting gradient realizes the efficient moisture permeability of 11.1 kg·m−1·d−1of the filter media. In addition, it shows the antibacterial activity of over 90 % against S.aureus and E.coli. The ergonomics experiments shows the heart rate and oxygen uptake are the key influencing factors reflecting the thermal comfort of the filter material. The composite filter material developed with excellent air and moisture permeability can provide a comfortable and safe breathing environment under the working environment of high temperature, high humidity and high labor intensity.

Field study of an arsenic removal plant for drinking water using activated carbon and iron in a rural community in the province of Pisco, Peru.

The presence of arsenic in Peru is a serious public health problem due to the geographical extension of populations that consume water with arsenic concentrations above the value recommended by the World Health Organization (WHO). An arsenic removal plant has been studied in a community of 50 families located in the province of Pisco, Peru, a filter media of activated carbon impregnated with iron (AC-Fe) was applied, the adsorption capacity of the material was studied against As(V) and As(III) species, also, a possible decrease in the adsorption capacity of chloride and sulfate ions. Modifications were made to the plant layout based on filtration columns and workflows. The arsenic level was reduced to levels recommended by the WHO, the plant production was estimated at 9,000 volumes of water bed until reaching its breakpoint. An optimum working flow rate of 1.8 m3 h-1 was found, it was also found that the zeolite column used for suspended solids removal did not contribute to the reduction of arsenic concentration, and the presence of ions did not reduce the arsenic removal capacity.

Development of CuO/Cu4(OH)6SO4 Nanoparticle Mixtures to Optimize the H2S Adsorption.

In this paper, we report the H2S adsorption behavior of a sorbent composed of mixtures of tenorite (CuO) and brochantite [Cu4(OH)6SO4]. These materials are readily prepared through the addition of NaOH(aq) to CuSO4(aq). They can be loaded onto polymer foams to create effective filters that can remove malodorous H2S gas, as evidenced by breakthrough tests. X-ray diffraction shows that the ratio of the two compounds in the mixture can be finely tuned by varying the amount of NaOH(aq) that is added to the reaction mixture. X-ray photoelectron spectroscopy shows that brochantite, like tenorite, has the ability to chemically adsorb H2S. Correlation of the H2S breakthrough data with scanning transmission electron microscopy measurements shows that the most effective sorbents contain nanoscale needle-like particles. These are likely to be formed largely by the tenorite phase. The samples with the greatest H2S adsorption efficacy contained less than 20% tenorite in the mixture, where these particles had the greatest abundance. The application of this sorbent onto porous substrates to create effective filters, along with the synthetic ease of its production, could allow this methodology to find use in a number of areas where H2S poses a problem. This could include areas where protective clothing is required to adsorb the gas from environments where there is a high level of H2S, for example, in wastewater treatment plants, oil and gas wells, or in the medical sector, where it could be deployed as filter media.

An efficacy investigation of combining Water Hyacinth (Eichhornia crassipes) with Filters as a Bioremediation for Leachate Contaminated Water

Pollution occurs everywhere and threatens rice field that require good quality water. Leachate is a pollutant from the Final Disposal Site (TPA) and flows into irrigation in the surrounding area. This study aims to experimentally analyse using a combination of Water Hyacinth Eichhornia crassipes and filter media (zeolite, charcoal, and gravel) to improve irrigation water quality and performance in a limited time. Samples were obtained from TPA Pakusari, Jember, East Java, Indonesia (-8,16956, 113.76129). There were three treatments: control, Water Hyacinth (WH), and Water Hyacinth + Filter (WHF). Multiparameter Aquacombo HM 3070 was used to test the parameters of Total Dissolved Solid (TDS), Conductivity, and pH. Determination of DO levels was done by the Winkler Method. Sample tests were performed every day (0-14 days). TDS and pH measurements showed that WH was a treatment that significantly reduced the effect. OD measurements showed significant increases in WH and WHF on the 7th day but not significant again on the 14th day. BOD measurements showed that control and WH decreased significantly starting the seventh day. Only the control treatment differed significantly on day 14 for conductivity measurements. Principle Component Analysis (PCA) showed that the WH and WHF treatments differed significantly, as a set of measured parameters between treatments formed different clusters on days 7 and 14. The significance of this study lies in its potential contribution to developing effective and sustainable methods to mitigate water pollution in agricultural settings, particularly in regions affected by leachate from disposal sites. The findings could be pivotal in improving irrigation water quality, thereby supporting healthier crop growth and sustainable agricultural practices.

Anaerobic baffled reactor followed by up-flow constructed wetland for treatment of municipal wastewater

A laboratory-scale anaerobic baffled reactor followed by up-flow constructed wetland are designed and developed with different filter media, and emergent plants. The effectiveness of an anaerobic baffle reactor (ABR) for settling down inorganic and treatment of the organic matter is observed in the present study. Further, two up-flow constructed wetland (UCW) units filled with Autoclaved Aerated Concrete (ACC) blocks and coconut shells as a filter media and wetland plants are combined for bio-phyto treatment. The performance of the treatment system is analyzed with hydraulic retention times (HRTs) of 12 h, 18 h, and 24 h. The removal of TSS, COD, TN, and TP are found to be 96 %, 84 %, 68 %, and 65.5 %, respectively, with 24 h HRT, which complied with the discharge standards. Due to the simplicity of construction as well as low operation and maintenance, the present treatment combination is considered eco-friendly, sustainable, and a cost-effective option for households or communities prior to its safe discharge. The treated water is ready to use for irrigation, gardening, floriculture, cleaning, and flushing.

Key factors maintaining catalytic ammonium oxidation activity of manganese oxide active filter media: The role of bicarbonate

The removal of ammonium (NH4+-N) via the catalytic oxidation of manganese oxide (MnOx) active filter media is a new technology. In this study, three different types of water (groundwater, surface water, and deionized water) were used to investigate the key factors affecting the sustainability of the catalytic activity of active MnOx filter media. The NH4+-N removal performance of the MnOx active filter media differed in different water environments, especially in deionized water, and the removal ability of NH4+-N was gradually decreased with increasing the running time. The continuous NH4+-N removal kinetics in different water environments were investigated. The rate constant k of the NH4+-N removal kinetics gradually decreased with NH4+-N removal, even in the groundwater environment, and the rate constant k decreased from 1.18 to 0.97 to 0.19. The addition of bicarbonate enhanced the ability to remove NH4+-N again, which confirmed that bicarbonate was the driving force for the continuous catalytic oxidation of NH4+-N. Based on the FTIR and XPS analysis results, the bicarbonate structure was consumed during the continuous removal of NH4+-N. Moreover, bicarbonate could affect the structure of MnOx, and then affected the electron transfer process of different valence manganese ions during the catalytic oxidation of NH4+-N, especially the conversion of Mn3+ to Mn2+. This study provides new insights into the theory of continuous catalytic oxidation by MnOx for NH4+-N removal.

Chemically tailored molecular surface modification of bamboo pulp fibers for manipulating the electret performance of electret filter media

The surface chemical composition of materials is essential for regulating their charge trapping and storage capabilities, which directly affect their electret performance. Although chemical modification of materials to alter electret performance has been investigated, the mechanism through which electret properties are regulated more systematically via chemical customization has not been elucidated in detail. Herein, p-phenylenediamine, benzidine and 4,4′-diaminotriphenyl, which have different conjugated strength functional groups, were selected to chemically tailor the surface of bamboo pulp fibers to regulate the electret properties and elucidate the regulatory mechanism more systematically. The results showed that the charge trapping and storage properties of materials could be regulated by introducing functional groups with different conjugated strengths to their surfaces, realizing the regulation of the electret properties. Moreover, the charge trapping and storage ability could be tailored more specifically by regulating the number of functional groups. By chemical customization to provide electrostatic effects to the materials, the purification time was reduced by approximately 45 %–52 %. More importantly, a relatively systematic mechanism was proposed to elucidate the effect of the conjugate group strength on the charge trapping and charge storage properties of the material. These findings will provide guidance for the investigation of chemical modifications to regulate the electret performance of materials.

Radiative cooling face mask based on mixed micro- and nanofibrous fabric

A type of personal protective face mask with thermal comfort function is developed based on the radiative cooling concept. We show that the cooling face mask, with the combination of PLA meltblown microfibers and a thin sheet of mixed electrospun micro- and nanofibers as filtration media and a silk fabric as inner supporting layer, can provide high reflectivity (>85 %) in the solar spectrum and high emissivity (>96 %) in the atmospheric window. Outdoor measurement of simulated skin temperature demonstrates the skin covered by our cooling mask could be ∼ 2.7℃ lower than that covered by commercial 3 M N95 mask. Our cooling mask exhibits excellent filtration performance with 99.98 % filtration efficiency and < 110 Pa pressure drop because of the reduced stacking density of the filtration media. This research has the potential of developing thermal management textiles.

PERENCANAAN INSTALASI PENGOLAHAN AIR LIMBAH (IPAL) PABRIK TEMPE DENGAN DIGESTER ANAEROBIK DAN BIOFILTER ANAEROBIK DI WILAYAH SEMARANG (Studi Kasus Pabrik Tempe Dampyak Gunung Pati Kota Semarang)

The tempe industry is a food industry that has the potential to pollute the environment from the liquid waste it produces. Liquid waste from the tempe processing process if it is immediately disposed of without going through the management process first will have an impact on environmental pollution. In Semarang City, precisely in Gunung Pati District, there is a medium-scale tempe processing factory. So far, the tempe factory's liquid waste is directly disposed of into a ditch behind the factory without processing the liquid waste first.This research is a quantitative research presented in the form of numbers and then explained in the form of descriptions. From the results of the wastewater quality test, the pollutant parameters BOD = 369 mg/L; COD = 28,000 mg/L; TSS = 0.991 mg/L; and pH = 4,3. According to the Regional Regulation of the Province of Central Java Number 5 of 2012 concerning Amendments to the Regional Regulation of the Province of Central Java Number 10 of 2004 this value still does not meet the requirements. The wastewater treatment plant that the researchers are planning is in the form of a holding tank; Equalization Tub; Anaerobic Digesters; Gas Holder; Initial Settling Tub; Anaerobic Biofilter using bioball filter media and steel nets as a barrier for bioballs where bacteria are grown; and Final Settling Tank. With an estimated effluent from the processing of BOD, COD, and TSS of 7.47225 mg/L; 189mg/L; and 0.00669 mg/L which means it meets the quality standard. From the planning results, it was obtained that the total budget plan for planning the tempe factory wastewater treatment plant was Rp. 111.280.021,49.

Efficient chemical and microbial removal of iron and manganese in a rapid sand filter and impact of regular backwash

Aeration followed by rapid sand filtration is a common method in drinking water treatment to remove iron (Fe) and manganese (Mn) from anoxic groundwater. To ensure the successful removal of Fe and Mn within a single filter, several factors such as raw water characteristics, backwash procedures and chemical and microbial interactions with the filter medium need to be considered. Here, we assess the characteristics of a single medium rapid sand filter with highly efficient removal of Fe and Mn. Using synchrotron X-ray spectroscopy, we show that formation of ferrihydrite-type Fe oxides in the top of the filter (0–50 cm) accounts for >95 % of the removal of dissolved Fe2+ in the filter. Birnessite-type Mn- oxides, which are thought to be biogenic, form over a wider depth interval (0–110 cm). Results of 16S rRNA gene amplicon sequencing indicate a corresponding distinct vertical stratification of the microbial community, with potential iron-oxidizing Gallionella, Leptothrix and Sideroxydans dominating in the upper part of the filter, and nitrifiers being more prevalent deeper in the filter. Besides Fe and Mn-oxide, Fe-flocs and bacteriological hollow sheets form in the upper part of the filter. Both the Fe-flocs, hollow Fe-sheets and part of the Fe and Mn coatings are removed through backwashing, thereby reducing the pressure difference measured over the filter medium linked to clogging of pores (from 14 kPa to 1.5 kPa) and ensuring continued water flow. Backwashing removes part of the Gallionella, but this does not negatively impact the filter performance. Strikingly, SEM imaging with EDS mapping revealed alternating layers of Fe and Mn-oxides on the coated grains throughout the filter. This indicates slow mixing of the filter medium between the upper 30 cm and the rest of the filter during backwashing. Slow mixing likely contributes to continued success of the filter by ensuring homogeneous filter bed growth, while still allowing for stratification of the microbial community.

Gelatin-reinforced cellulose nanofiber composite cryogels for effective separation of small particulate matter in air

Herein, novel composite aerosol filters solely comprising renewable materials were designed using gelatin as a reinforcement agent and aqueous tert-butyl alcohol (TBA) as a dispersing medium for the cellulose nanofiber skeleton. The prepared composite cryogels exhibited distinct spider-web-like crosslinked structures and nanoporous architectures with porosity exceeding 98.8 % and density of less than 0.018 g/cm3. These composite filters exhibited high filtration efficiency and a robust and flexible mechanical structure due to gelatin reinforcement; furthermore, their quality factor exceeded the target threshold of 0.01 Pa−1 for 300 nm particle size. The filtration performance and mechanical properties of the composite filters could be tailored by adjusting the cellulose nanofiber (CNF), gelatin, and TBA contents, enabling the preparation of cryogels with a firm and strong structure. This study introduces ultraporous solids based on nanocellulose (NC) cryogels, which are promising, novel, and green materials for the production of advanced high-performance filter media for aerosol separation. Furthermore, the aforementioned approach is promising for the preparation of mechanically robust nanoporous biomaterials suitable for diverse applications such as heat and thermal insulation.

Arabic Audio-Visual Translation Censorship: A Corpus Study of Subtitles of Three Films

Audio-visual translation is one of the most dynamic types of translation. As this form of translation deals with culture as well as language media is often altered to remove sensitive elements. This is common in the Arab world where censor boards filter media before its rerelease. The strategies employed in censorship have been influenced by advancements in technology and mass media narratives. This paper therefore examines the subtitling strategies employed in film censorship by examining three American films, namely, The Hangover, Bridesmaids, and What Women Want. The research adopts Pederson’s taxonomy (2017) as a theoretical framework in addition to the three strategies proposed in this study ‘tone down,’ ‘upgrading,’ and ‘normalizing’. The results indicated that censorship is common in the Arab world in the forms of omission and euphemism. Moreover, it was found that subtitles employ high register language when rendering the low register language of the source text despite the availability of low register language choices. The study recommends that dialectical and non-standard Arabic be used for the rendering of sensitive elements. Future studies may build on these findings to improve the understanding of censorship trends and unconventional movements.

A Study on the Correlation Between Chinese Youth's Use of Internet Social Media and the Formation of Polarization Bias Cognition: Taking Contradictory Gender Bias as an Example

The phenomenon of group polarization caused by modern online social media is becoming increasingly severe, such as gender conflicts, increased intergenerational misunderstandings, extreme fixed cognition leading to online violence, etc. This work takes the phenomenon of contradictory gender bias as an example, discusses and designs experimental ideas to explore the correlation and impact of social media usage frequency on the phenomenon of contradictory gender bias, Through a questionnaire survey, 188 men and women aged 18-40 were surveyed on their social media usage habits and the degree of conflicting gender biases. Quantitative analysis and testing were conducted to determine the correlation between the frequency of social media usage and the degree of gender biases. The conclusion was drawn that internet social media filters fixed audience groups through big data, forming a fixed atmosphere of group public opinion. The characteristics of social media groups lead to group polarization, and obvious opposition leads to conflicts, Conflict also intensifies and forms solidified extreme radical biases and perceptions among groups. This study analyzes the common issues of group bias cognition and conflict opposition in internet social media from the perspective of social psychology, providing a comprehensive thinking model and experimental direction.

Removal of microbial aerosol using titania/chitosan composites in air conditioning systems

The humid environment of the air conditioning system promotes the growth of microorganisms on the filter media. Using filter media with antibacterial properties can solve this problem. As a photocatalytic material, TiO2 is often added to certain products as an antimicrobial. Chitosan (CS) is an antibacterial substance that can be processed into fibers, so it can be considered as a substitute for polypropylene (PP) fiber, which is currently commonly used as a filter medium. Unlike previous studies, this study used an air duct experiment system to simulate the operating conditions of air conditioning systems, and TiO2 was supported by CS and PP fiber, respectively. Results show that TiO2/CS exhibited better filtration and antibacterial properties at a 3% TiO2 impregnation concentration. When the basic weight of CS is 190 g/m2, the filtration efficiency can reach 96.8% with only 6 W ultraviolet, but the pressure drop is only 28 Pa. At the same time, the survival of bacteria on CS filter media is about 60% lower than that on PP and bacterial shedding is decreased by more than 35%. Due to the excellent filtration and antibacterial properties of TiO2/CS composite, its use in air conditioning systems will be of interest.

Examination of the Efficiency of Fabric Filter Media in Two-Stage Crossflow Pre-Filtration of Turbid Surface Water Using the Davies Flow Equation

Clogging of rapid sand filters during heavy rainfall causes surface water treatment plants to stop their operations until the river water turbidity decreases to a level that the rapid sand filter is capable of filtering. As clogging of rapid sand filters is impediment in surface water treatment, two-stage crossflow pre-filtration with fabric filter media (linen, crepe-backed satin, burlap, and cotton) was considered in a previous study by Davis and Ekwue (2020) as a possible solution. Pre-filtration with linen fabric filter medium was found to be the most efficient at retaining particles. The present paper incorporated properties of various fabrics previously measured and identified by Davis and Ekwue (2020) with the aim of identifying ideal fabric properties that were effective in removing particles from turbid water. Mechanisms of filtration (surface straining, depth filtration and cake filtration) depicted by each selected fabric during two-stage crossflow pre-filtration were identified and compared to the operation of standard filter media (absorbent, adsorbent, biological and woven). The Davies equation was used to calculate the flow of water through single layer and four layers of fabric filter media. Results indicate that no one specific fabric property could be used to proclaim a fabric as the ideal filter media, but rather all properties of the various fabric contribute to their performance during filtration.Linen fabric was once again determined as the fabric type most efficacious at retaining particles during two-stage crossflow pre-filtration of turbid river water and is therefore recommended.

Formation of Actinobacteria biofilms during groundwater treatment

The paper presents the results of a study of the reasons for the formation of biofilms during the purification of groundwater with use of natural sorbents. Analysis of the microbial complexes structure at different stages of water treatment showed that their numbers increased after filtration through a load with granular activated carbon. In some cases, it remained high in storage tanks containing purified water. In fact, at all stages of water treatment, representatives of Actinobacteria were found in the community structure, which formed biofilms in the technical system, as well as after 14 days of storage in bottled water. It was established that representatives of actinomycetes in the planktonic state formed flakes from mycelium, and on filter media they formed biofilms in the form of a complex structured community. Actinobacteria strains isolated from water and activated carbon biofilms differed in their cultural and morphological characteristics. However, they were characterized by a common ability to produce polymeric substances that formed a protective matrix and promoted cell adhesion to various substrates and surfaces. Scanning electron microscopy shown that sporulation promoted survival during all stages of groundwater treatment, including chlorination and ozonation.

A circular economy approach for geotextile reuse following lake water filtration

Eutrophication in lake systems is intensifying. To reduce this possible scenario, a method for suspended solids and associated nutrient removal by a novel on-site remediation has been investigated, using nonwoven geotextiles as filter media. These procedures generate clogged geotextile layers with captured suspended solids on them. To become more sustainable, circular economy principles were employed, more precisely reuse. Thus, this investigation aims to assess the potential reuse strategies by washing clogged layers and determining their possible reuse. The washing method was pressurized water (i.e., using a gardening pump sprayer). Preliminary results have shown the efficiency of the washing method in removing visible geotextile (non-woven) clogging, with permeate flow rates reaching values close to the initial process values. The geotextile apparent opening size increased by an order of 20%. Also, no geotextile fibre disruption was observed by scanning electron microscope (SEM) imagery, indicating its possible reuse. The dilute liquid waste preliminary findings showed high concentrations of some metals such as manganese, (112.72 μg/L) and zinc (88.12 μg/L) in addition to phosphorus (120.18 μg/L) which requires additional studies. The washed geotextile leaching test did not indicate any contaminants in the permeate which would enable geotextile layer reuse for lake water filtration.

Bicomponent core/sheath melt-blown fibers for air filtration with ultra-low resistance.

With the escalating air pollution and frequent outbreaks of airborne diseases, there is a growing demand for personal protective filtration media. Melt-blown nonwovens have proven to be highly effective in capturing tiny particles, but their tightly packed fiber assemblages are more resistant to airflow and less comfortable to breathe. Here, we present a one-step melt-blown spinning process for the production of bicomponent core/sheath (BCS) crimped fibers and their application in high-efficiency, low-resistance air filtration. Fiber curl is caused by unbalanced internal stresses resulting from differences in the structure components, resulting in uneven shrinkage inside and outside the fibers. The resulting CM@S-2 filtration media features a uniform fiber curl and a porous fiber mesh structure, which reduces air filtration resistance. Under the same filtration conditions, the filtration efficiency of CM@S-2 (96.58% vs. 95.58%), filtration resistance (56.1 Pa vs. 108.0 Pa), quality factor (0.061 Pa-1vs. 0.029 Pa-1), and dust holding capacity (10.60 g m-2vs. 9.10 g m-2) were comparable to those of the single-component polypropylene filters. The filtration efficiency of the CM@S-2 remained above 94.0% after 30 days of indoor storage. Computational Fluid Dynamics (CFD) simulation demonstrated that crimped fibers effectively reduce pressure surges on the filter media caused by fiber accumulation. In comparative tests with commercial masks, the CM@S-2 cartridge masks demonstrated superior air permeability compared to commercial masks under similar filtration conditions. In conclusion, the bicomponent core/sheath melt-blown fibers significantly reduce air resistance and show excellent potential for application in protective masks.

Ocena pokazatelja kvaliteta semena hibrida paprike tokom klijanja

The aim of the research was to evaluate the influence of the hybrid and the medium for germination testing on indicators of pepper seed quality. The obtained results should provide an answer as to whether the application of different growing media for testing seed germination can lead to discrepancies between test results in quality indicators for hybrid seeds. The seed quality of three pepper hybrids: KG 2025 F1, KG 2129 F1 and KG 2032 F1 was tested on two growing media (filter paper and substrate). Statistical analysis of germination energy, total germination, diseased seedlings and dead seeds showed highly significant differences (r&lt;0.01) under the influence of the hybrid factor. The growing media factor also had a highly significant effect on all examined quality indicators , except for total germination. A significantly lower number of abnormal and diseased seedlings was found on the filter paper compared to the substrate. A highly negative significant correlation (r =-0.90951, p≤0.001) was recorded only between total germination and diseased seedlings. The obtained results indicate that the application of different media for testing the germination of hybrid pepper seeds can lead to inconsistencies in the obtained values for all evaluated quality indicators.

Determination of absorption properties of natural sorbents under dynamic conditions

The relevance of research on the absorption properties of sorbents is due to the need for an individual approach in the selection of filter media for wastewater treatment, depending on their chemical composition. In the presented article sorption properties of sorbents were studied under dynamic conditions. For this purpose, a laboratory-experimental installation for the treatment of natural and waste water was mounted. In the research three types of filtering loads were used: 1 - homogeneous load from activated carbon of BAU-A mark; 2 - combined load from activated carbon and zeolite with particle size of 5 mm; 3 - zeolite with fraction of 5 mm, 3 mm, and 1 mm. Among the studied samples of sorbents, zeolite loading with particle sizes of 5 mm, 3 mm, and 1 mm showed the best performance. Other types of loadings, such as activated carbon BAU-A and combined carbon loadings with zeolite were ineffective, because the sorption coefficient did not meet the MAC requirements.