Search Results (68)

High-temperature particulate matter (PM) filtration remains a fundamental challenge, because most fiber filters not only face the challenge of high temperatures but also suffer from an inherent trade-off between capture efficiency, pressure drop, and service life. This paper reports a hierarchical layered zirconia (ZrO₂) ceramic fiber aerogel featuring a continuous multiscale gradient. The aerogel was prepared by gradient air-blown spinning, and the resulting structure has directional order, with the fiber diameter gradually decreasing from upstream to downstream, thus forming a pore size gradient and achieving hierarchical particle interception across multiple scales. This rational design simultaneously suppresses surface clogging and reduces flow resistance, resolving the longstanding trade-off between efficiency and permeability. Consequently, this aerogel achieves an ultra-high filtration efficiency of 99.96%, a low pressure drop of 156 Pa, and a high dust-holding capacity of 101 g m⁻². The material also exhibits outstanding mechanical toughness (80% compressive strain elasticity and 25.75% tensile fracture strain) and thermal stability up to 1000 °C. Moreover, it maintains over 99.95% filtration efficiency at high temperatures and can be fully regenerated through 800 °C heat treatment. This work establishes a structure-based design paradigm for high-temperature filtration media and provides a scalable pathway for next-generation industrial flue gas purification. Full article

Composting chicken manure is a source of significant ammonia (NH₃) emissions, which, because of propagation, contributes to the eutrophication of the environment and decreases in air quality. Therefore, it is reasonable to use methods to limit its emission into the atmosphere. Biofiltration, using the metabolic activity of nitrifying and heterotrophic microorganisms capable of oxidizing ammonia, is an effective method to reduce ammonia emissions. In addition, the performance of the biofiltration process depends on operational parameters such as the humidity of the medium, the temperature, the contact time of the gas with the biofiltering medium, and the chemical composition and structure of the filter material. The aim of the study was to evaluate the effectiveness of biofilter fillings in reducing ammonia emissions from composting chicken manure along with the identification of factors allowing us to determine the proposed design solution as the most advantageous in terms of efficiency. Experiments on reducing odour emissions with biofiltration were carried out in two compact composting reactors, in which a compost mixture with a C:N ratio of 10:1 was used. The mixture was prepared in a ratio of 5:1 of chicken manure to the structuring material, with wheat straw used as the structuring material. Based on the results of the research on the course of the composting process, high values of ammonia concentration were recorded. Ammonia concentrations of 886 ppm (composter 1) and 811 ppm (composter 2) were recorded, which confirms the intensive nature of this gas emissions during the process of stabilizing the chicken manure. As part of the conducted research, the effectiveness of biofiltration in reducing ammonia emissions was evaluated by analysing the influence of the aeration intensity of the biofilter (20 dm³/h and 50 dm³/h), directly determining the time of contact of the gas with the bed (EBCT—Empty Bed Contact Time). Coconut-activated carbon was used as a filter bed, which was an effective carrier for the development of microorganisms responsible for the biological removal of ammonia from waste gases generated during composting. In addition, this material showed the ability to physically adsorb ammonia, thus supporting the process of its elimination. Each of the test stations has been equipped with a biofiltration installation. To determine the effectiveness of biological removal of ammonia and to assess the legitimacy of the use of selected strains of microorganisms in the process of biological removal of ammonia, the bed of one of the biofilters (biofilter 2) was inoculated with a strain of nitrifying bacteria. During the study, the high efficiency of ammonia removal because of biofiltration was noted in each of the configurations. In the case of an aeration intensity of 20 dm³/h, a reduction in emissions of 99% was achieved; with a higher aeration value, i.e., 50 dm³/h, the efficiency was 89%. These results indicate that the intensity of aeration has a significant impact on the efficiency of the biofiltration process. The analysis of a biofilter enriched with a strain of nitrifying bacteria requires long-term testing. This is important to reliably determine the effect of inoculation on the efficiency of the biological removal of ammonia in biofilters. It has been shown that optimizing these factors allows us to achieve a reduction in ammonia emissions of up to 90%, while minimizing the formation of unpleasant odours. The use of biofiltration in composting systems for organic waste of animal origin is an effective, sustainable solution that fits into the idea of sustainable development, combining the efficiency of air purification technology with environmental protection and the responsible management of resources. This study demonstrates that biofiltration using coconut-shell-activated carbon is an effective and economical method for reducing ammonia and odour emissions from composting chicken manure. The results provide valuable theoretical and practical information on emissions management in organic waste composting processes. Data from this study could be useful in developing strategies to minimize odour emissions, including from the agricultural sector. Full article

This study aims to address the lack of systematic research on how air filter cleaning affects pollutant distribution in subway stations, an urgent issue for ensuring indoor air quality in enclosed underground transit environments. Taking a representative subway line in Xi’an, China, as the research object, we monitored and analyzed pollutant concentrations (including particulate matter and microorganisms) at air supply outlets (near, semi-far, and far from the air filter) and different locations in a single station hall before and after filter cleaning, with the goal of clarifying the cleaning effect and its variation with distance from the air supply. The results show that, before cleaning, pollutant distribution exhibits distinct spatial characteristics: PM₁₀ concentration is 16.7% higher at outlets closer to the filter, while PM_2.5 and PM_1.0 concentrations are 22.4% and 19.7% higher at distant outlets, respectively. After cleaning, all pollutants are significantly reduced: PM₁₀ at near outlets decreases by 25.9%, PM_2.5 and PM_1.0 at far outlets drop by 44.2% and 42.7%, respectively, and the total numbers of bacteria and fungi in the air supply meet national hygiene standards. A key novel finding is that cleaning has differentiated effects on particle sizes across locations; it is more effective for larger particles at near outlets and for smaller particles at far outlets. This research not only quantifies the purification effect of filter cleaning but also reveals the spatial variation law of its impact, providing practical guidance for optimizing subway ventilation system maintenance (e.g., tailored cleaning strategies for different locations) and ensuring passenger health. Full article

This review presents a modern comprehensive analysis of the physicochemical characteristics of carbon materials for the sorption of gases. The main classes of carbon sorbents are considered as follows: nanotubes, activated carbon, graphene, fullerene, composite materials, and organic vapors. Modern methods of modification of carbon materials are systematized. Particular attention is paid to the effect of particle size, morphology, and porous structure on the kinetics and equilibrium characteristics of adsorption. The results of experimental and theoretical studies of the adsorption of the gases (CO₂, SO₂, NO_x, H₂S, NH₃, and CO) are analyzed. A comparative economic analysis of carbon materials is carried out, taking into account the cost of production and estimated costs of modification. Modern areas of application of carbon sorbents are analyzed as follows: industrial gas purification, automotive filters, air conditioning systems, personal protective equipment, and gas sensors. Particular attention is paid to the study of the prospects and future of materials. Prospective development directions are considered, including the creation of hierarchically porous structures, the development of self-healing materials, and integration with artificial intelligence to optimize adsorption processes. The cost of graphene and nanotube production is predicted to decrease by 50–70% by 2030, which will lead to an expansion of their commercial application. Full article

Indoor exposure to particulate matter (PM_2.5 and PM₁₀) remains a significant public health problem, especially in high-traffic areas, where outdoor pollution, building characteristics, and user activity jointly influence indoor air quality. This study aims to synthesise and compare the effectiveness of key technical solutions to reduce indoor PM concentrations in different types of buildings. A comprehensive review and comparative analysis of published experimental and field studies were conducted, covering residential, educational, office, medical, sports, and heritage buildings. The interventions evaluated included mechanical ventilation and filtration systems, portable HEPA air cleaners, integrated building envelope solutions, airflow optimisation strategies, and selected auxiliary technologies. Reported performance metrics such as baseline indoor and outdoor PM concentrations, air exchange rate (ACH), filter class, clean air delivery rate (CADR), and percentage reduction were systematically analysed. The results indicate that mechanical filtration, particularly high-efficiency HVAC (Heating Ventilation and Air-Conditioning) systems and HEPA filters, provide the most reliable and repeatable reductions in PM_2.5 and PM₁₀, especially under controlled airflow and recirculation conditions. Integrated approaches that combine airtight building envelopes, mechanical ventilation, and local air purification achieved the highest overall effectiveness. The findings confirm that successful PM mitigation requires context-specific multicomponent strategies tailored to building type, outdoor pollution load, occupancy, and ventilation design. Full article

Indoor air quality (IAQ) in high-rise residential buildings is an increasing concern, especially in hot and humid climates where prolonged indoor exposure elevates health risks. This study evaluates the performance of Fresh Air Handling Units (FAHUs) using two complementary approaches: (1) real-time sensor data to quantify IAQ conditions and (2) occupant survey responses to capture perceived comfort and pollution indicators. The results show that floor level did not predict satisfaction, even though AQI data revealed clear differences between flats, suggesting perceptions are driven more by sensory cues than by actual pollutant levels. Longer weekday exposure emerged as a stronger predictor of dissatisfaction. These gaps between perceived and measured IAQ highlight the need for improved ventilation scheduling and greater occupant awareness. FAHUs were found to be inefficient, consuming 21–26% of total building energy while lacking pollutant-specific monitoring capabilities. To address these issues, the study recommends the integration of IoT-enabled sensors for real-time pollutant detection, enhanced facade sealing to minimize external infiltration, and the upgrade of filtration systems with HEPA filters and UV purification. Additionally, AI-driven predictive maintenance and automated ventilation optimization through Building Management Systems (BMS) are suggested. These findings offer valuable insights for improving IAQ management in high-rise buildings, with future research focusing on AI-based predictive modeling for dynamic air quality control. Full article

This systematic review assesses indoor air quality (IAQ) in tropical residences (Köppen Af/Am/Aw), explicitly linking IAQ to ventilation from in situ monitoring and, when relevant, occupant surveys (surveys synthesized qualitatively). This focus is warranted by the scarcity of tropical, housing-specific evidence. Searches were performed exclusively in Google Scholar (25 August 2024–5 August 2025; English/Spanish) under PRISMA, with documented queries/filters; eligible studies reported residential settings, tropical climate, and IAQ–ventilation linkage. Results show a regulatory mosaic with few binding residential limits and heterogeneous protocols that hinder comparison. Robust patterns include cooking-related particle peaks, penetration of traffic dust, humidity-driven VOC/formaldehyde emissions, and mold growth under deficient hygrothermal control. CO₂ is a useful operational indicator of ventilation yet insufficient for risk assessment without PM and VOC monitoring. Evidence supports source control, cross-ventilation and/or on-demand extraction/outdoor-air supply, humidity management, and filtration/purification to avoid particle ingress during ventilation. Reporting of sensor performance (calibration, drift, RH/T effects) is inconsistent, and targeted evaluations of TVOC/formaldehyde and window screens (mesh) are scarce. We conclude that tropical residential IAQ management requires multi-parameter, continuous monitoring, standardized reporting, and trials integrating ventilation, dehumidification, and filtration under real occupancy, alongside adaptive regulation and passive tropical design augmented by light mechanical support and informed occupant behavior. Full article

This article examines the effects of climate change on the 32 million inhabitants of the Megalopolis of Central Mexico (MCM), which is threatened by chaotic urbanization, land-use changes, the deforestation of the Forest of Water by organized crime, unsustainable agriculture, and biodiversity loss. Expensive hydraulic management extracting water from deep aquifers, long pipes exploiting water from neighboring states, and sewage discharged outside the endorheic basin result in expensive pumping costs and air pollution. This mismanagement has increased water scarcity. The overexploitation of aquifers and the pollution by toxic industrial and domestic sewage mixed with rainfall has increased the ground subsidence, damaging urban infrastructure and flooding marginal neighborhoods with toxic sewage. A system approach, satellite data, and participative research methodology were used to explore potential water scarcity and weakened water security for 32 million inhabitants. An alternative nature-based approach involves recovering the Forest of Water (FW) with IWRM, including the management of Natural Protected Areas, the rainfall recharge of aquifers, and cleaning domestic sewage inside the valley where the MCM is found. This involves recovering groundwater, reducing the overexploitation of aquifers, and limiting floods. Citizen participation in treating domestic wastewater with eco-techniques, rainfall collection, and purification filters improves water availability, while the greening of urban areas limits the risk of climate disasters. The government is repairing the broken drinking water supply and drainage systems affected by multiple earthquakes. Adaptation to water scarcity and climate risks requires the recognition of unpaid female domestic activities and the role of indigenous people in protecting the Forest of Water with the involvement of three state authorities. A digital platform for water security, urban planning, citizen audits against water authority corruption, and aquifer recharge through nature-based solutions provided by the System of Natural Protected Areas, Biological and Hydrological Corridors [SAMBA] are improving livelihoods for the MCM’s inhabitants and marginal neighborhoods, with greater equity and safety. Full article

Air and seawater samples were collected in 2022–2023 and analyzed through a common DNA extraction, purification, and Next-Generation Sequencing protocol. The study targeted bacteria, archaea, fungi, and plant-associated taxa to compare community structure across both milieus. Given the scarcity of data on environmental microbiomes in Greece, we aimed to investigate further the diversity and variability of these microbiomes for the first time, using barcoding to provide data on microbial signatures in the air and seawater. Sequencing data revealed significant spatial and seasonal variability and a high diversity and richness of microbiome communities in both habitats. After quality filtering, we detected 21 phyla and 345 genera of bacteria and archaea, 3 phyla and 149 genera of fungi, and 17 Viridiplantae orders in the urban air. At the same time, in the recreational waters, we isolated 20 phyla and 420 genera of bacteria and archaea, 2 phyla, and 53 genera of fungi and 19 orders of Viridiplantae. Many of the fungal and bacterial taxa detected in this study can be potentially pathogenic. These findings highlight the potential of DNA barcoding as a reliable tool for integrative environmental monitoring, offering insights into the composition of environmental microbiomes. Microbiome monitoring is valuable for the environment and health, and it will be more efficient by integrating DNA analysis with the development of open databases and artificial intelligence. Full article

Particulate matter (PM) and volatile organic compounds (VOCs) are major air pollutants that can cause significant risks to public health. To mitigate exposure, fibrous filters have been widely utilized for air purification. In this study, we developed electrospun silk fibroin/poly (ethylene oxide)/cyclodextrin (SF/PEO/CD) nanofibers as multifunctional air filters capable of efficiently reducing PM_2.5 and degrading VOCs. The resulting SF/PEO/10CD demonstrated the best multifunctional filtration performance, achieving PM_2.5 capture efficiencies of 91.3% with a minimal pressure drop of 4 Pa and VOC removal efficiency of 50%. These characteristics highlight the potential of the SF/PEO/10CD nanofiber with effective, multifunctional properties and environmental benefits for sustainable air filtration application. Full article

Air purification is a key process aimed at removing harmful impurities and providing a safe and comfortable environment for human life and work. This study presents the results of an investigation into the composition, textural, and sorption properties of a multichannel carbon filtering material developed for air purification from biological (infectious) contaminants. The filtering block has a cylindrical shape and is manufactured by extrusion of a plastic composition based on carbonized rice husk with the addition of binding agents, followed by staged thermal treatment (calcination, activation, and demineralization). The filter’s effectiveness is based on the inactivation of pathogenic microorganisms as the air passes through the porous surface of the sorbent, which is modified with broad-spectrum antiseptic agents (active against bacteria, bacilli, fungi, and protozoa). X-ray diffraction analysis revealed the presence of amorphous carbon in a tubostratic structure, with a predominance of sp- and sp²-hybridized carbon atoms not incorporated into regular graphene lattices. IR spectroscopy demonstrated the presence of reactive functional groups characteristic of the developed porous structure of the material, which is capable of selective sorption of antiseptic molecules. SEM surface analysis revealed an amorphous texture with a loose structure and elements in the form of spherical semi-ring formations formed by overlapping carbon plates. An experimental setup was also developed using cylindrical multichannel carbon blocks with a diameter of 48 mm, a length of 120 mm, and 100–120 longitudinal channels with a cross-section of 1 mm². The obtained results confirm the potential of the proposed material for use in air purification and disinfection systems under conditions of elevated biological risk. Full article

The article presents the results of developing carbon-silicon sorbents that demonstrate high efficiency in capturing various types of dust particles, along with partial antibacterial activity. Dust particles ranging from 0.65 to 150 microns were effectively retained by the sorbent, with organic dust capture efficiency varying between 74% and 98%, making these sorbents suitable for air purification in highly polluted indoor environments. The antibacterial activity was tested on Bacillus paramycoides and Pseudomonas koreensis strains using the diffusion method on a solid nutrient medium. Testing showed that sorbent samples with different concentrations of the active ingredient exhibited varying degrees of bacterial growth suppression, with Sample No. 2 demonstrating the highest activity. Optimizing the sorbent composition and increasing the concentration of active components may enhance its antibacterial properties. These sorbents hold great potential for use in air purification systems with additional protection against bacterial contamination, making them promising for environments with high standards for air hygiene and cleanliness. Full article

The spread of airborne diseases such as COVID-19 underscores the need for effective indoor air quality control. This review focuses on ventilation strategies and portable air purifiers as key mitigation solutions. Ventilation systems, including natural and mechanical approaches, can reduce pathogen concentrations by improving airflow. However, combining ventilation with portable air purifiers, particularly those using HEPA filters, ESP filters, and UV-C radiation, can enhance Indoor air quality. While HEPA and ESP filters focus on trapping airborne particles, UV-C radiation can inactivate pathogens by disrupting their RNA. A review of UV air purifiers reveals a lack of studies on their efficacy and effectiveness in real-world settings. A thorough investigation into the performance of this mitigation solution is necessary, focusing on varying key factors, such as purifier placement, airflow dynamics, and UV dosage, to ensure optimal effectiveness. High-fidelity computational methods are essential in accurately assessing these factors, as informed by the physics of airborne transmission. Such advanced computations are necessary to determine the viability of portable UV air purifiers in mitigating airborne transmission in enclosed environments such as hospitals and public spaces. Integrating advanced air purification technologies with proper ventilation can improve safety in indoor environments and prevent future disease-related outbreaks. Full article

The prevalence of airborne pathogens in indoor environments presents significant health risks due to prolonged human occupancy. This review addresses diverse air purification systems to combat airborne pathogens and the factors influencing their efficacy. Indoor aerosols, including bioaerosols, harbor biological contaminants from respiratory emissions, highlighting the need for efficient air disinfection strategies. The COVID-19 pandemic has emphasized the dangers of airborne transmission, highlighting the importance of comprehending how pathogens spread indoors. Various pathogens, from viruses like SARS-CoV-2 to bacteria like Mycobacterium (My) tuberculosis, exploit unique respiratory microenvironments for transmission, necessitating targeted air purification solutions. Air disinfection methods encompass strategies to reduce aerosol concentration and inactivate viable bioaerosols. Techniques like ultraviolet germicidal irradiation (UVGI), photocatalytic oxidation (PCO), filters, and unipolar ion emission are explored for their specific roles in mitigating airborne pathogens. This review examines air purification systems, detailing their operational principles, advantages, and limitations. Moreover, it elucidates key factors influencing system performance. In conclusion, this review aims to provide practical knowledge to professionals involved in indoor air quality management, enabling informed decisions for deploying efficient air purification strategies to safeguard public health in indoor environments. Full article

Indoor air quality determines the comfort, health, and wellbeing of people in buildings. Windows are the optimal elements for providing natural ventilation and fresh air, but the outside contains suspended particles that can be harmful in high concentrations. This work presents an openable and double-glazed façade component with a cavity that includes a series of slats that filter the air and depurate it by means of a photocatalytic reaction (TiO₂). This component integrates the functions of ventilation, solar protection, and air purification, which were analysed in the slat and the façade component to approve a preliminary design. To this end, it was applied to a specific case, a non-residential building at a latitude 41° N in a Mediterranean climate. The results show the optimal dimensions according to solar radiation and ventilation in this specific case and the method used to obtain them, along with the increase in the temperature of the incoming air with respect to the outside (10 °C). Finally, the results obtained from a photocatalytic coating sample show that the NOx degradation can be up to 9%. All these results confirm the applicability of this component in buildings and pave the way for further research. Full article