Gaseous Contaminants Research Articles

Proof of concept of a novel in tandem biofilter photobioreactor system for valorization of volatile organic compounds: mineralization of methanol vapors coupled with use of CO2 as a carbon source for Arthrospira maxima growth

AbstractBACKGROUNDMethanol, a common air pollutant, can be converted to CO2 by biofiltration. In turn, biofilter CO2 streams, contributing to the greenhouse effect, could represent a zero‐cost carbon source for microalgal production. To assess the potential of the combination of both bioprocesses, cultivation of Arthrospira maxima, a major source of added‐value natural products, was carried out with three different carbon sources (bicarbonate mineral medium, CO2 from ambient air, and CO2 from a methanol biofilter outlet).RESULTSMethanol vapors were almost completely treated in the biofilter, achieving an elimination capacity of 148 ± 18 g m−3 h−1 for an inlet load of 157 ± 12 g m−3 h−1, while producing an average of 152 ± 42 g m−3 h−1 of CO2. Compared to cultivation in classic bicarbonate mineral medium, the resulting CO2 concentration in the biofilter outlet (0.5 ± 0.1% (v/v)) allowed for a 20% higher final production of A. maxima (1.3 g dry weight (DW) L−1 of medium). Moreover, the cultivation of A. maxima significantly reduced the carbon footprint of the biofilter, with a fixation rate of 302 mg CO2 L−1 h−1. Additionally, enriched CO2 concentrations coming from the biofilter outlet allowed for a 117% higher A. maxima productivity rate than ambient air (76.5 ± 2.9 vs. 35.3 ± 1.3 mg DW L−1 d−1).CONCLUSIONSubstantial reduction of the cost of microalgae production and treatment of gaseous contaminants can be carried out in tandem. Further optimization of hybrid bioprocesses could represent a win–win opportunity from both environmental and economic viewpoints. © 2021 Society of Chemical Industry (SCI).

Cardio-respiratory disease with contrasted air pollution levels in three municipalities of Abidjan district hospitals, Cote d’Ivoire

BACKGROUND AND AIM: The human health effects for both particulate matter and gaseous contaminants are global public health concern. The objective of this study was to assess any variations of air pollution in contributions from waste burning, heavy motor vehicle traffic and biomass burning and the impact on health in Abidjan, with special attention to cardiorespiratory diseases, METHODS: A survey was conducted during two years in 5 hospitals, 3 months during the rainy and the dry season. We estimated air pollution levels simultaneously with health care assessment with a particular attention for cardio-respiratory diseases. PM2.5 concentration and cardiorespiratory diseases outcomes were recorded in a questionnaire sheet in the district hospitals. The relative Risks (RR) of the relationship between the observed cardiorespiratory outcomes and air pollution exposure were estimated using a Poisson regression model. RESULTS:The results showed that PM2.5 Concentrations from the waste burning and traffic sites were comparable with annual averages of 28.51 µg/m3 and 29.69 µg/m3 respectively. In Yopougon, where domestic fires are common, the annual average is drastically higher at 155.1 µg/m3. PM2.5 were elevated in both seasons with an average of 145µ/m3; more than the one recommended by WHO. Also, cardiorespiratory diseases occurred in 66% and the most affected were women (54%) and children under 18 years old. The highest PM2.5 concentrations were due to biomass burning, seen in Yopougon. Outpatient visits for cardiorespiratory symptoms showed a significant association with PM2.5 concentrations during the rainy season and respiratory outpatient visits were significant throughout the entire year. Overall, we estimate that 143 hospital visits could have been avoided during the rainy seasons of our study period CONCLUSIONS:Accessing to air pollution data has been difficult in developing countries. This survey was one the first conducted so far in Côte d’Ivoire addressing pollutant concentrations and cardiorespiratory outcomes. KEYWORDS: Air pollution, Cardio-respiratory disease, health care

Compound-specific carbon isotope analysis of volatile organic compounds in complex soil extracts using purge and trap concentration coupled to heart-cutting two-dimensional gas chromatography–isotope ratio mass spectrometry

Compound-specific carbon isotope analysis (CSIA) is a powerful tool to track the origin and fate of organic subsurface contaminants including petroleum and chlorinated hydrocarbons and is typically applied to water samples. However, soil can form a significant contaminant reservoir. In soil samples, it can be challenging to recover sufficient amounts of volatile organic compounds (VOC) to perform CSIA. Soil samples often contain complex contaminant mixtures and gas chromatography combustion isotope ratio mass spectrometry (GC-C-IRMS) is highly dependent on good chromatographic separation due to the conversion to a single analyte. To extend the applicability of CSIA to complex volatile organic compound mixtures in soil samples, and to recover sufficient amounts of target compounds for carbon CSIA, we compared two soil extraction solvents, tetraglyme (TGDE) and methanol, and developed a heart-cutting two-dimensional GC-GC-C-IRMS method. We used purge & trap concentration of solvent-water mixtures to increase the amount of analyte delivered to the column and thus lower method detection limits. We optimized purge & trap and chromatographic parameters for twelve target compounds, including one suffering from poor purge efficiency. By using a 30 m thick-film non-polar column in the first and a 15 m polar column in the second dimension, we achieved good chromatographic separation for the target compounds in difficult matrices and high accuracy (trueness and precision) for carbon isotopic analysis. Tetraglyme extraction was shown to offer advantages over methanol for purge & trap concentration, leading to lower target compound method detection limits for CSIA of soil samples. The applicability of the developed method was demonstrated for a case study on soil extracts from a former manufacturing facility. Our approach extends the applicability of CSIA to an important matrix that often controls the long-term fate of contaminants in the subsurface.

Interaction of Ammonia with Nafion and Electrolyte in Electrocatalytic Nitrogen Reduction Study.

Ammonia synthesis by electrochemical nitrogen reduction reaction (NRR) is a promising alternative to the Haber-Bosch process. Accurate measurement of produced ammonia requires rigorous criteria, which rely on a deeper understanding of ammonia characteristics. Herein, we systematically investigated the interaction of ammonia with Nafion membrane and electrolyte to reveal factors that may induce deviation in ammonia measurements. We demonstrated desirable characteristics of Nafion membrane as a separator in view of the low adsorption rate and low diffusion rate for ammonia. But one should be aware of the possible contaminants pre-existing in the membrane. It was also observed that the acid electrolyte had a much greater affinity for ammonia compared with base electrolyte. Specifically, the acid electrolyte is more vulnerable to potential ammonia contaminant in the feeding gas, whereas base electrolyte is inclined to lose produced ammonia under a continuous nitrogen flow. The findings provide a deeper understanding of ammonia's behavior in NRR test and help obtain accurate and credible ammonia measurements.

Influencing factors of carbonyl compounds and other VOCs in commercial airliner cabins: On-board investigation of 56 flights.

Volatile organic compounds (VOCs) as a non-negligible aircraft cabin air quality (CAQ) factor influence the health and comfort of passengers and crew members. On-board measurements of carbonyls (short-chain (C1 -C6 )) and other volatile organic compounds (VOCs, long-chain (C6 -C16 )) with a total of 350samples were conducted in 56 commercial airliner cabins covering 8 aircraft models in this study. The mean concentration for each individual carbonyl compound was between 0.3 and 8.3μg/m3 (except for acrolein & acetone, average=20.7μg/m3 ) similar to the mean concentrations of other highly detected VOCs (long-chain (C6 -C16 ), 97% of which ranged in 0-10μg/m3 ) in aircraft cabins. Formaldehyde concentrations in flights were significantly lower than in residential buildings, where construction materials are known formaldehyde sources. Acetone is a VOC emitted by humans, and its concentration in flights was similar to that in other high-occupant density transportation vehicles. The variation of VOC concentrations in different flight phases of long-haul flights was the same as that of CO2 concentration except for the meal phase, which indicates the importance of cabin ventilation in diluting the gaseous contaminants, while the sustained and slow growth of the VOC concentrations during the cruising phase in short-haul flights indicated that the ventilation could not adequately dilute the emission of VOCs. For the different categories of VOCs, the mean concentration during the cruising phase of benzene series, aldehydes, alkanes, other VOCs (detection rate>50%), and carbonyls in long-haul flights was 44.2µg/m3 , 17.9µg/m3 , 18.6µg/m3 , 31.5µg/m3 , and 20.4µg/m3 lower than those in short-haul flights, respectively. Carbonyls and d-limonene showed a significant correlation with meal service (p<0.05). Unlike the newly decorated rooms or new vehicles, the inner materials were not the major emission sources in aircraft cabins. Practical Implications. The on-board measurements of 56flights enrich the VOC database of cabin environment, especially for carbonyls. The literature review of carbonyls in the past 20years contributes to the understanding the current status of cabin air quality (CAQ). The analysis of VOC concentration variation for different flight phases, flight duration, and aircraft age lays a foundation for exploring effective control methods, including ventilation and purification for cabin VOC pollution. The enriched VOC data is helpful to explore the key VOCs of aircraft cabin environment and to evaluate the acute/chronic health exposure risk of pollutants for passengers and crew members.

Large-Eddy Simulation of Plume Dispersion in the Central District of Oklahoma City by Coupling with a Mesoscale Meteorological Simulation Model and Observation

Contaminant gas dispersion within an urban area resulting from accidental or intentional release is of great concern to public health and social security. When estimating plume dispersion in a built-up urban area under real meteorological conditions by computational fluid dynamics (CFD), a crucial issue is how to prescribe the input conditions. There are typically two approaches: using the outputs of a mesoscale meteorological simulation (MMS) model and meteorological observations (OBS). However, the influences of the different approaches on the simulation results have not been fully demonstrated. In this study, we conducted large-eddy simulations (LESs) of plume dispersion in the urban central district of Oklahoma City under real meteorological conditions by coupling with a MMS model and OBS obtained at a single stationary point, and evaluated the two different coupling simulations in comparison with the field experiments. The LES–MMS coupling showed better performance than the LES–OBS one. The latter one also showed a reasonable performance comparable to the acceptance criteria on the model prediction within a factor of two of the experimental data. These facts indicate that the approach using observations at a single stationary point still has enough potential to drive CFD models for plume dispersion under real meteorological conditions.

The Challenge of Indoor Air Quality Management: A Case Study in the Hospitality Industry at the Time of the Pandemic

Air quality management represents a reason for concern in indoor environments, especially now that the COVID-19 pandemic has shown how microbial aerosols pose a threat to human health, requiring proper monitoring. This is particularly true in public and working environments, where the turnover of occupants is high. The hospitality sector, in particular, has been severely affected by limitations related to emergency containment, and it needs to redefine its operations in the perspective of a “new normal” in the post-COVID-19 era. Considering the necessity to provide consistent information about indoor air quality, promote adequate management and increase safety, we developed a case study in cooperation with a major hotel in Turin. A sensing network has been implemented based on corporate-grade monitoring devices, compliant with the RESET standards, recently proposed and applied here to the hospitality sector for the first time. The network is able to detect the concentration of gaseous contaminants and fine particulate matter in semi-continuous mode. The study involved areas of the hotel with different purposes, such as guestrooms, hall, kitchen, restaurant and fitness center. Several valuable insights emerged in support of air quality management and pathways for future research can be outlined, based on the innovative dataset developed.

Investigation of an Intensified Thermo-Chemical Experimental Set-Up for Hydrogen Production from Biomass: Gasification Process Performance—Part I

Biomass gasification for energy purposes has several advantages, such as the mitigation of global warming and national energy independency. In the present work, the data from an innovative and intensified steam/oxygen biomass gasification process, integrating a gas filtration step directly inside the reactor, are presented. The produced gas at the outlet of the 1 MWth gasification pilot plant was analysed in terms of its main gaseous products (hydrogen, carbon monoxide, carbon dioxide, and methane) and contaminants. Experimental test sets were carried out at 0.25–0.28 Equivalence Ratio (ER), 0.4–0.5 Steam/Biomass (S/B), and 780–850 °C gasification temperature. Almond shells were selected as biomass feedstock and supplied to the reactor at approximately 120 and 150 kgdry/h. Based on the collected data, the in-vessel filtration system showed a dust removal efficiency higher than 99%-wt. A gas yield of 1.2 Nm3dry/kgdaf and a producer gas with a dry composition of 27–33%v H2, 23–29%v CO, 31–36%v CO2, 9–11%v CH4, and light hydrocarbons lower than 1%v were also observed. Correspondingly, a Low Heating Value (LHV) of 10.3–10.9 MJ/Nm3dry and a cold gas efficiency (CGE) up to 75% were estimated. Overall, the collected data allowed for the assessment of the preliminary performances of the intensified gasification process and provided the data to validate a simulative model developed through Aspen Plus software.

Chemical Weapons in the Iran-Iraq War (1980–1988) 5. Accumulated Experience in the Treatment of Lesions Caused by Sulfur Mustard

ulfur mustard was widely used during the Iran-Iraq war (1980–1988) and in other conflicts in the Middle East. Due to its availability, it can be used by terrorist organizations on the territory of the Russian Federation. Iran is the only country, against which mustard gas was used in modern warfare. The aim of this work is to analyze and summarize the experience of treating of sulfur mustard exposure, accumulated by Iranian specialists during the Iran-Iraq war (1980–1988). The UN official documents and materials, declassified CIA documents, articles of Iranian authors as well as other open sources have been used during its preparation. The Iraqi army used mustard gas in two aggregate states: liquid and dry. Dry mustard gas was a novelty of that war. It was a powdered silica steeped in mustard gas, with a particle size of less than 5 μm. The first signs and symptoms of poisoning could appear after 15 minutes, while acute poisoning effects of exposure to mustard gas vapour or liquid were typically delayed for several hours. The reasons for the severe mustard lesions of the servicemen were the lack of personal protective equipment, untimely evacuation from the mustard gas contamination zone, and the absence of mobile reserves of clean water and degassing installations in battle formations. Iranian experts consider 0.5% sodium hypochlorite solution to be the most effective decontaminant. The only safe antidote is sodium thiosulfate, administered within 60 minutes after exposure to mustard gas. During the evacuation of victims and their treatment in hospitals it is necessary, in severe cases, to insert an intravenous catheter, carry out a tracheotomy with the installation of a tracheotomy tube, and use bronchoscopy as early as possible to flush the bronchi. The treatment of skin and eye lesions should be conservative. In case of a corneal perforation, if its diameter is more than 2 mm – keratoplasty, if it is less – cyanoacrylate glue. Treatment of respiratory lesions aims to relieve symptoms and reduce the severity of complications. For this, bronchodilators, antitussives, mucolytics and, if necessary, antibiotics are used. The use of corticosteroids should be limited to the treatment of those patients with bronchospasm, who can not be treated by bronchodilators. The Iranians also consider gene therapy and treatment with mesenchymal stem cells to be the promising method used in the treatment of lung lesions

Integration of Distributed Generating Systems for Non-Linear Loads

The independent small-scale networks including sustainable power sources have been used in remote regions around the globe. Nonetheless, the irregularity of vitality sources may cause an enormous variance of the miniaturized scale framework recurrence. Because of consistently expanding vitality utilization, rising open familiarity with ecological assurance, and relentless advancement in power deregulation, distributed generation (DG) frameworks have pulled in expanded intrigue. Wind and photovoltaic (PV) power age are two of the most encouraging sustainable power source advancements. Fuel cell (FC) frameworks likewise show incredible potential in DG utilizations of things to come because of their quick innovation improvement and numerous benefits they have, for example, high effectiveness, zero or low outflow (of contamination gases), and adaptable measured structure. In proposition investigated work Integration of Distributed Generating Systems for Non-straight Loads will be proposed. A run-of-the-mill wind-PV-diesel reconciliation which comprises of diesel generator, PV framework, wind turbine generator (WTG), BESS, and burden, is utilized for the proposed models and controllers. We reenact and Integration Distributed Generating Systems for Non-straight Loads on the MATLAB/SIMULINK and portions of coordinated vitality frameworks are analyzed. The coordinated PV framework is normally controlled to work in the maximum power point tracking (MPPT) mode. The battery vitality stockpiling framework is worked inconsistent force charging or releasing mode. So as to give an incorporated vitality framework associated with lattice relying upon singular vitality necessities, the Integrated Energy Systems can be extra to a current vitality source to lessen petroleum product utilization or an independent for complete non-renewable energy source uprooting Through the broad joining of vitality foundations it is conceivable to upgrade the supportability, adaptability, steadiness, and productivity of the general vitality framework. The reproduction of incorporated vitality frameworks is done in MATLAB/SIMULINK. And all framework results will be done by Matlab reproduction is proposed for disconnected smaller scale matrices with sustainable sources. In the exhibited method, the pitch point controller is intended for wind turbine generator (WTG) framework to smooth breeze power yield. The proposed procedure is tried in a regular secluded incorporated small-scale network with both PV and wind turbine generators.

Circulating fluidized bed gasification of solid recovered fuels - Results from gasification and gas filtration tests

Fluidized bed gasification technology offers an attractive way to use inhomogeneous biomass residues and various waste-derived feedstocks in power and heat production as well as in various circular economy concepts based on the synthesis gas route. A fluidized bed gasification process development (PDU) plant of 200 kW capacity was operated with Solid Recovered Fuels (SRFs) and demolition wood. In part of the tests carried out with SRF, deposits were formed in the gas lines, and the pressure drop of the filter increased as well. However, optimal combination of gasification, gas cooling and filtration conditions were found to achieve a stable pressure drop, avoid deposit formation and to achieve efficient removal of gas contaminants. The effects of the operating conditions on the achieved carbon conversion and formation of tars and other gas contaminants were studied. The produced gas was filtered at 370-500 °C using two alternative filtration systems applying ceramic bag filters or ceramic fiber filters. The removal efficiency of waste-derived trace metals and chlorine was determined at different filtration temperatures.

Improved photocatalytic oxidation performance of gaseous acetaldehyde by ternary g-C3N4/Ag-TiO2 composites under visible light

In the process of photocatalytic oxidation (PCO), titanium dioxide (TiO2) shows excellent capabilities. However, when TiO2 is used to remove volatile organic compounds (VOCs), there are some drawbacks including weak adsorption of gaseous contaminants, insufficient utilization of sunlight, and rapid recombination of photogenerated carriers. Herein, a TiO2-based ternary heterogeneous photocatalyst, g-C3N4/Ag-TiO2, was successfully fabricated to photodegrade gaseous acetaldehyde (one of the representatives of oxygenated VOCs) under visible light. Among the various samples, the g-C3N4/50 wt% Ag-TiO2 exhibited an excellent photocatalytic activity, which was 5.8 times of bare TiO2. The mineralization efficiency of acetaldehyde was also increased by 3.7 times compared to bare TiO2. The substantial improvement in the PCO performance of the ternary system can be associated with the good adsorption to acetaldehyde gas and light-harvesting capability, as well as improved charge separation process. The application of Langmuir-Hinshelwood kinetic model suggested that relative humidity played a significant role in the VOCs degradation. Also, the photodegradation of gaseous acetaldehyde primarily occurred on the catalysts surface. Based on several characterizations, i.e., UV–vis spectroscopy, photoluminescence spectrum, photocurrent spectroscopy and electron spin-resonance test, a suitable degradation mechanism is proposed. This study provides a novel ternary photocatalyst with improved photocatalytic performance and stability, which can be used for the low-concentration VOCs abatement in the indoor environment.

The geophysical recognition of a vapor-cored geothermal system in divergent plate tectonics: The Alalobeda (Alalobad) field, Ethiopia

We show the results of a geophysical survey carried out in the Alalobeda (Alalobad) geothermal field (Afar, Ethiopia). The site is located on the western margin of the NW-SW Tendaho Graben, at the intersection with the NNE-SSW Main Ethiopian Rift.The survey included 121 Magnetotelluric (MT) and Time Domain Electromagnetics (TDEM) soundings, and 300 gravity records. We applied 3D MT and gravity inversion to target a previously inferred high-T (220 °C) near neutral pH liquid-dominated chloride reservoir.Geophysical modelling identified the graben basin structure, with normal fault stepping in the Afar Stratoid basalts (2485 kg/m3), underlying a low-density (2035 kg/m3) and conductive (1 Ohm m) sedimentary cover. Along the graben shoulder, a density anomaly (+200 kg/m3) suggests a propylitization zone corresponding to the reservoir, underlying the typical conductive clay cap updomings and downdomings of high-T geothermal systems.A major conductive plume, without an appreciable gravity signature, occurs in the graben shoulder. Integration with the geochemical results allows to interpret it as a vapor-cored system. The hot spring water CO2, H2S and Cl content indicates the contamination of magmatic gases into the reservoir that produce fluid acidification while ascending from a deep source. The local bulk resistivity (10 Ohm m) is explainable by assuming conductive permeating acid fluids (10 S/m), an enhanced porosity (20%) and a significant gas saturation (20%). The absence of an appreciable density increase is also justified by the hypothesised porosity and the gas fraction. Since the acidic fluids are neutralised by interaction with the host rock, the sampled waters are nearly pH-neutral.Our results suggest the first occurrence of a vapor-cored system in divergent plate tectonics, such as the Tendaho Graben sector of the Afar rift zone.

Hydrophobic deep eutectic solvents as attractive media for low-concentration hydrophobic VOC capture

Emissions of volatile organic compounds (VOCs) are known to be significant human health and ecological risks. Absorption is a classical process applied to eliminate air pollutants, yet the removal efficiency of gaseous contaminants is often curbed by the mass transfer resistance between absorption liquids and hydrophobic VOCs. This work aims to evaluate the feasibility of capturing VOCs from exhaust through the use of hydrophobic deep eutectic solvents (DESs). Among the examined DESs, hydrophobic DESs whose hydrogen bond acceptors (HBAs) and hydrogen bond donors (HBDs) are both fatty acids with long alkyl chains (i.e., decanoic acid [DecA] and lauric acid [LauA]) achieve the highest absorption capacity of toluene at 9.94 mg toluene per g DES at 30 °C and 800 ppm toluene with an HBA:HBD molar ratio of 1:3. Hydrophobic interactions between the fatty acids and toluene are critical for improving the VOC absorption ability of DESs, as the toluene solubility increases with an increase in the alkyl chain length of the fatty acid eutectics. The compiled results suggest that effective hydrophobic VOC removal can be realized by the proposed hydrophobic fatty acid eutectics, [LauA][DecA], and the physical absorption nature of toluene in fatty acid eutectics benefits facile recovery and recycling.

An integrated study on the geochemical, geophysical and geomechanical characteristics of the organic deposits (Coal and CBM) of eastern Sohagpur coalfield, India

Coal mining, especially the underground mines are often encountered with several types of geological constraints, where massive-hard roof and trapped gas are the most serious threats leading to catastrophic (fatal) effects in form of roof falls, mine explosion and gas contamination. Thus, for enhancing the safety of underground coal mines, identification of aforesaid constraints during detailed exploration is very essential. The minable seams of Sohagpur Coalfield are often associated with rich Coal Bed Methane (CBM) content, which enhances their economical importance, but the gas content along with the presence of stable sandstone roof parallely induces challenges during their extraction. CBM also acts as an environmental hazard having twenty-one times more greenhouse effect than carbon dioxide (CO2). Therefore, the present paper attempts to investigate the depositional environment of the high-quality methane-rich sub-bituminous reserves of eastern Sohagpur Coalfield through integration of geochemical, geophysical and geomechanical analysis of the drilled boreholes along with their respective gas content. The results showed that the six major Barakar coal seams possessed nearly consistent distribution in terms of reserve distribution and chemical properties. These seams consisted of good quality reserves (Grade: G5-G8) with high heat values and organic content, and had less impurity content. These coal seams are overlain by stable roof having lower cavablity in form of thick hard medium-grained sandstone beds with moderate elasticity and strength. The seam structures showed a stable profile without any abrupt discontinuity except Bahmni-Chilpa fault in southern part of block. Some of the higher rank coal seams also contained potential CBM content. Statistical analysis was also carried out for understanding the distribution of reserve properties and monitored their interdependence using suitable fitting tools. Thus, the present study helped in summarizing different aspects related to reserve quality, roof properties and gas content for understanding the geology and working environment of coal reserves of less explored but economically important Central Indian coalfields.

Fabrication and characterization of keratin starch biocomposite film from chicken feather waste and ginger starch

The disposal of chicken feather through burning or burying is not environmentally compliant due to the accompanying release of greenhouse gas and underground water contamination. Thus, the transformation of this bio-waste into a bio-composite film is considered not only a sustainable strategy for disposal of this solid wastes but also an attractive alternative to developing an efficient nanostructured biomaterial from renewable bio resource. In the present study keratin extracted from chicken feather waste in combination with ginger starch were fabricated into a bio-composite film. The fabricated bio-composite films were characterized, using different analytical techniques. The physicochemical characteristics of ginger starch showed a moisture content of 33.8%, pH of 6.21, amylose and amylopectin contents of 39.1% and 60.9%, respectively. The hydration capacity of the starch was 132.2% while its gelatinization temperature was 65.7 °C. Physical attributes of the bio-composite film, such as surface smoothness and tensile strength increased significantly (p < 0.05) with increasing keratin content, while its transparency and solubility showed significant (p < 0.05) decrease with increasing keratin level. The various blends of the bio-composite films decayed by over 50% of the original mass after 12 days of complete burial in soil. Based on the results obtained in this study, the addition of keratin to starch bio-composite showed remarkable improvement in mechanical properties, such as tensile strength and surface smoothness. The bio-composite film exhibited appropriate stability in water, although future study should be carried out to evaluate its thermal stability. Nonetheless, the fabricated keratin-starch bio-composite showed desirable characteristics that could be optimized for industrial applications.

Analysis of contaminants and their formation mechanism in the desiccation-dissociation process of organic impurity of waste glass

The recovery of waste glass is an important issue in the fields of social sustainable development and resource recovery. The removal of organic impurity is the first step in the recovery of waste glass. Currently, desiccation-dissociation technology is advised to remove the organic impurity from waste glass. However, the risks of the organic impurity desiccation-dissociation process of waste glass have not been reported in the literature. In this paper, the environmental risks of the organic impurity desiccation-dissociation process of waste glass were assessed. The assessment results indicated that none of TSP (0.143 mg/m3), PM10 (0.090 mg/m3), heavy metals in air and residue after desiccation-dissociation were contaminated. However, the gas contained abundant organic contaminants, especially benzene, whose content was up to 5.26%. Molecular dynamics simulation and contaminant formation pathways analysis indicated that the formation of gaseous organic contaminants was because overmuch small molecular free radicals were generated at 200 °C and combined with each other. Hence, reducing the temperature of desiccation-dissociation, wearing gas masks, and placing organic gas contaminant absorption liquids are necessary protective measures. This paper provides scientific data for the green development of organic impurity desiccation-dissociation technology of waste glass. Meanwhile, this paper makes up for the shortage of the environmental information of the organic impurity desiccation-dissociation of waste glass.

Results of studies of processes of clearing of gaseous contaminants and ventilating the atmosphere of habitable pressurized modules in a space station

The paper presents partial analytical solutions for equations describing variation in trace amounts of carbon dioxide in the atmosphere of habitable spaces within pressurized modules (PM) of a space station. The solutions may find practical application in calculations of concentrations for any contaminants, or for air flow through the purification system. It is shown that in a case where low-toxic contaminants are released into the PM atmosphere, it would be enough to cycle 3 volumes of the PM air through the purification system when the system operates without the breakthrough concentration (without the residual concentration of the contaminant at the outlet from the purification system), in order to achieve the 95% purification of the atmosphere. For highly toxic contaminants this value should be significantly increased depending on the maximum allowable concentration of the substance (47 volumes and more — up to 99.9% purification). The paper also considers variation in the concentration of the contaminant in the atmosphere during intermixing of atmospheres between PMs using intermodular ventilation. As a result, new analytical solutions were obtained for practical calculations which make it possible to determine gaseous contaminant concentration at any point in time and the time of the final equalization of the contaminant concentration in the space station atmosphere. It was determined that the time needed for complete mixing of gaseous contaminants through intermodular ventilation between two PMs does not depend on the initial concentrations of the contaminants (and only depends on the PM volumes and the intermodular ventilation flow rate). Key words: space station, pressurized module atmosphere, carbon dioxide, atmosphere purification, variation in concentration, air flow, atmosphere mixing.

RESULTS OF STUDIES OF THE PROCESSES OF CLEARING OF GASEOUS CONTAMINANTS AND VENTILATING THE ATMOSPHERE OF HABITABLE PRESSURIZED MODULES IN A SPACE STATION

The paper presents partial analytical solutions for equations describing variation in trace amounts of carbon dioxide in the atmosphere of habitable spaces within pressurized modules (PM) of a space station. The solutions may find practical application in calculations of concentrations for any contaminants, or for air flow through the purification system. It is shown that in a case where low-toxic contaminants are released into the PM atmosphere, it would be enough to cycle 3 volumes of the PM air through the purification system when the system operates without the breakthrough concentration (without the residual concentration of the contaminant at the outlet from the purification system), in order to achieve the 95% purification of the atmosphere. For highly toxic contaminants this value should be significantly increased depending on the maximum allowable concentration of the substance (47 volumes and more — up to 99.9% purification). The paper also considers variation in the concentration of the contaminant in the atmosphere during intermixing of atmospheres between PMs using intermodular ventilation. As a result, new analytical solutions were obtained for practical calculations which make it possible to determine gaseous contaminant concentration at any point in time and the time of the final equalization of the contaminant concentration in the space station atmosphere. It was determined that the time needed for complete mixing of gaseous contaminants through intermodular ventilation between two PMs does not depend on the initial concentrations of the contaminants (and only depends on the PM volumes and the intermodular ventilation flow rate). Key words: space station, pressurized module atmosphere, carbon dioxide, atmosphere purification, variation in concentration, air flow, atmosphere mixing.

Architectural choices aimed at reducing the air pollution by vehicle emissions in residential areas

Introduction. The formation of an optimal microclimate and ensuring the purity of atmospheric air in residential areas is possible in urban planning design practice by regulating the wind regime, which determines the thermal state of a person and the quality of the living environment, the temperature and humidity regime. The aim of the study is to assess the impact of the width, density, and planning techniques of main streets on the aeration regime and reduction of the concentration of motor transport emissions in the air of residential areas. Material and methods. The research was carried out both in full-scale conditions on the streets of large cities and residential buildings’ models at a scale of 1:20 using cup anemometers. Results. The regularities of the formation of the aeration regime and the level of gas contamination of main streets with different planning and development methods are established. The dependences of the coefficient of air flow transformation in terms of the speed on the width of streets and the size of gaps between buildings are obtained. Planning conditions that exclude the possibility of a closed circulation of impurities in street canyons are determined. The spatial and temporal dynamics of air pollution of transport communications in residential areas of settlements is studied. Conclusions. Hygienic standards for the content of motor transport emissions in the air of residential areas are provided by the optimal aeration mode, formed by choosing the width, position of the route, number of floors, planning techniques, and density of development of main streets. Simultaneously, it is necessary to introduce measures aimed at reducing the gross emissions of pollutants into the atmosphere and eliminating foci of atmospheric pollution on the transport networks of cities. When selecting urban planning decisions that ensure the environmental quality of the living environment of settlements in different geographical areas, it is necessary to consider the peculiarities of spatial-temporal dynamics of air pollution by transport and communications, due to changes in meteorological conditions and fluctuations in the intensity of traffic by hour of day, day of week and season of the year.