The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
D. C. Carslaw - One of the best experts on this subject based on the ideXlab platform.
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On the changing seasonal cycles and trends of ozone at Mace Head, Ireland
Atmospheric Chemistry and Physics, 2005Co-Authors: D. C. CarslawAbstract:A seasonal-trend decomposition technique based on a locally-weighted regression smoothing (Loess) approach has been used to decompose monthly ozone concentrations at Mace Head (Ireland) into trend, seasonal and irregular components. The trend component shows a steady increase from 1990?2004, which is confirmed by statistical testing which shows that ozone concentrations at Mace Head have increased at the p=0.06 level by 0.18±0.04 ppb yr?1. By considering different Air mass origins using a trajectory analysis, it has been possible to separate Air masses into "Polluted" and "unPolluted" origins. The seasonal-trend decomposition technique confirms the different seasonal cycles of these Air mass origins with unPolluted Air mass maxima in April and Polluted Air mass maxima in July/August. A detailed consideration of the seasonal component reveals different behaviour depending on the Air mass origin. For baseline unPolluted Air arriving at Mace Head there has been a gradual increase in the seasonal amplitude, driven by a declining summertime component. The amplitude of the seasonal component of baseline Air is controlled by a maximum in April and a minimum in July. For Polluted Air mass trajectories, there was a substantial reduction in the amplitude of the seasonal component from 1990?1997. However, post-1997 results indicate that the seasonal amplitude in Polluted Air masses arriving at Mace Head is increasing. Furthermore, there has been a shift in the months controlling the size of the seasonal amplitude in Polluted Air from a maximum in May and minimum in January in 1990 to a maximum in April and a minimum in July by 2001. This finding suggests that there has been a steadily decreasing influence of Polluted Air masses arriving from Europe. These Air masses have therefore increasingly taken on the attributes of baseline Air.
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On the changing seasonal cycles and trends of ozone at Mace Head, Ireland
Atmospheric Chemistry and Physics Discussions, 2005Co-Authors: D. C. CarslawAbstract:A seasonal-trend decomposition technique based on a locally-weighted regression smoothing (Loess) approach has been used to decompose monthly ozone concentrations at Mace Head (Ireland) into trend, seasonal and irregular components. The trend component shows a steady increase from 1990?2004, which is confirmed by statistical testing that shows that ozone concentrations at Mace Head have increased at the p=0.06 level by 0.18±0.04 ppb yr?1. By considering different Air mass origins using a trajectory analysis, it has been possible to separate Air masses into "Polluted" and "unPolluted" origins. The seasonal-trend decomposition technique confirms the different seasonal cycles of these Air mass origins with unPolluted Air mass maxima in April and Polluted Air mass maxima in July/August. A detailed consideration of the seasonal component reveals different behaviour depending on the Air mass origin. For baseline unPolluted Air arriving at Mace Head there has been a gradual increase in the seasonal amplitude, driven by a declining summertime component. The amplitude of the seasonal component of baseline Air is controlled by a maximum in April and a minimum in July. For Polluted Air mass trajectories, there was a substantial reduction in the amplitude of the seasonal component from 1990?1997. However, post-1997 results indicate that the seasonal amplitude in Polluted Air masses arriving at Mace Head is increasing. Furthermore, there has been a shift in the months controlling the size of the seasonal amplitude in Polluted Air from a maximum in May and minimum in January in 1990 to a maximum in April and a minimum in July by 2001. These results indicate that the characteristics of baseline Air are becoming more important in Polluted Air masses arriving at this location.
Christian Kennes - One of the best experts on this subject based on the ideXlab platform.
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Steady- and transient-state performance of a thermophilic suspended-growth bioreactor for α-pinene removal from Polluted Air
Chemosphere, 2013Co-Authors: María Montes, María C. Veiga, Eldon R. Rene, Christian KennesAbstract:Abstract The removal of α-pinene from Polluted Air was examined under thermophilic conditions (50 °C) in one- and two-liquid phase continuous stirred tank bioreactors (CSTBs). Steady-state experiments were performed at different gas residence times, and α-pinene concentrations, corresponding to inlet loading rates between 0.5 and 38 g m−3 h−1 in the one-liquid phase CSTB, and between 2.9 and 176 g m−3 h−1 in the two-liquid phase CSTB. The presence of a second liquid-phase (5% v/v silicone oil) increased the maximum elimination capacity (85.7 g m−3 h−1) by ∼6-fold compared to the one-liquid phase CSTB. During transient-state experiments, the CSTB with silicone oil could withstand a higher α-pinene shock load (110 g m−3 h−1) than the CSTB operated without silicone oil (70 g m−3 h−1). Besides, the thermophilic specific substrate utilization rates were estimated from batch assays, reaching 89 and 340 μ g α -pinene mg biomass - 1 d - 1 , in the absence of or presence of silicone oil, respectively.
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Optimization of the treatment of carbon monoxide-Polluted Air in biofilters.
Chemosphere, 2008Co-Authors: Yaomin Jin, Ling Guo, María C. Veiga, Christian KennesAbstract:Abstract This work is the first extensive study on the removal of carbon monoxide from Polluted Air in biofilters. It compares the performance of two packing materials, namely lava rock alone and a mixture of peat and lava rock. The results show that the biofilter packed with the mixture of peat and lava rock performed much better than the other one. The effect of operating conditions as, among others, the inlet concentration and the empty bed residence time (EBRT) were studied. A maximum elimination capacity of 33 g m −3 h −1 was obtained with the mixed packing with more than 85% removal efficiency at EBRT of 3 min or more. Somewhat lower performances were reached at shorter EBRT. The results presented here suggest that the mixture of lava rock and peat, subject to further optimization, offers potential for the biological removal of CO from Polluted gas streams.
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Development of a novel monolith-bioreactor for the treatment of VOC-Polluted Air.
Environmental technology, 2006Co-Authors: Yaomin Jin, María C. Veiga, Christian KennesAbstract:A novel bioreactor packed with ceramic monolith colonized by a toluene-degrading culture was investigated in order to assess its suitability for waste gas treatment. Operational parameters that were considered included start-up of the bioreactor, toluene loading rate, changes in gas flow rate, liquid feed mode, and steady-state operation. This is the first report on the treatment of toluene-Polluted Air in such a biological monolith reactor. Data on performance and stability have been obtained showing that this system is suitable for waste gas treatment. Removal efficiencies around 90% could be maintained at different gas flow rates, although this value gradually dropped when increasing the load above 30 g m−3 h−1. Interestingly, omitting the continuous feed of a liquid trickling phase improved the reactor's performance. One potential drawback that needs to be minimized is related to clogging after long term operation. Further studies aimed at optimizing this novel application would allow reaching a high ...
Donald R. Blake - One of the best experts on this subject based on the ideXlab platform.
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Evolution of mixing state of black carbon in Polluted Air from Tokyo
Geophysical Research Letters, 2007Co-Authors: Manabu Shiraiwa, Nobuyuki Takegawa, Yutaka Kondo, Yuzo Miyazaki, Nobuhiro Moteki, Donald R. BlakeAbstract:[1] The evolution of the mixing state of black carbon aerosol (BC) was investigated using a single-particle soot photometer (SP2) in Polluted Air transported from Tokyo. Ground-based measurements of aerosols and trace gases were conducted at a suburban site (Kisai) 50 km north of Tokyo during July–August 2004. The ratio of 2-pentyl nitrate (2-PeONO2) to n-pentane (n-C5H12) was used to derive the photochemical age. According to the SP2 measurement, the number fraction of thickly coated BC (Shell/Corel Ratio > ca. 2) with a core diameter of 180 nm increased at the rate of 1.9% h−1, as the photochemical clock proceeded under land-sea breeze circulation. Positive matrix factorization was applied to investigate the time-dependent contributions of different coating materials using the mass concentrations of sulfate, nitrate, and organics measured using an aerosol mass spectrometer. The main coating materials found in this study were sulfate and organics.
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Evolution of submicron organic aerosol in Polluted Air exported from Tokyo
Geophysical Research Letters, 2006Co-Authors: Nobuyuki Takegawa, Takuma Miyakawa, Yutaka Kondo, Donald R. Blake, Yugo Kanaya, Makoto Koike, M. Fukuda, Yuichi Komazaki, Yuzo Miyazaki, A. ShimonoAbstract:[1] Ground-based measurements of aerosols and trace gases were conducted at an urban site in Tokyo (Komaba) and a site 50 km to the north (Kisai) during July–August 2004. An Aerodyne aerosol mass spectrometer (AMS) was deployed at each measurement site to investigate the chemical evolution of submicron organic aerosol (OA) in Polluted Air. The mass concentrations of OA at the Kisai site were systematically higher than those at the Komaba site and were correlated with ozone under southerly conditions. The rate of increase of OA at the Kisai site is investigated using the photochemical age derived from the ratio of alkyl nitrates to their parent hydrocarbons. The OA concentrations in processed Air (age of 8–16 h) were 4–5 times larger than those in fresh emissions (age ∼ 0), suggesting that the OA concentrations can be significantly enhanced within ∼0.5 days under conditions of high photochemical activity.
Jaroslav Oral - One of the best experts on this subject based on the ideXlab platform.
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Alternative arrangement of unit for thermal processing of wastes from Polluted Air
Journal of Cleaner Production, 2004Co-Authors: Petr Stehlík, Roman Stulir, L. Bebar, Jaroslav OralAbstract:Abstract New efficient equipment for the thermal treatment of gas wastes from Polluted Air (incineration of volatile organic compounds and carbon monoxide) has been developed recently. This equipment can be used in various branches of industry (for the treatment of Polluted Air from paint shops, chemical cleaning systems, degreasing processes, printing machines, gas wastes from various chemical processes, for the thermal treatment of off-gases originating in refineries, in the production of plastic, the pharmaceutical industry, the food industry, laboratories, etc.). A principal idea of this equipment is based on placing the cylindrical combustion chamber inside a heat exchanger–Polluted Air preheater. Main advantages of this equipment are as follow: compactness and utilizing heat losses from the combustion chamber for additional preheating the Polluted gas. Modified equipment for catalytic treatment can be used as an alternative unit. Various options of arrangement can be applied in industrial practice. This unit can be used as a compact one (minimization of space requirement owing to a convenient arrangement of fans), over pressure (only Air fan), under pressure (only flue gas fan — recommended especially in cases where the Polluted Air is supplied by pressure). Waste to energy arrangement is that in the case of an excessive concentration of pollutants–combustibles. Then the energy of the outlet flue gas can be utilized not only for the Polluted Air preheating but also for steam generation, water heating or other purposes.
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Efficient equipment with special heat exchanger for thermal treatment of Polluted Air-experiments, computations, applications
Heat Transfer Engineering, 2003Co-Authors: Roman Stulir, Petr Stehlík, Jaroslav OralAbstract:A quite new and unique piece of equipment for the thermal treatment of gas wastes (i.e., the incineration of volatile organic compounds contained in Polluted Air) has been developed. This compact equipment is characterized by a cylindrical combustion chamber placed inside a heat exchanger—a Polluted Air preheater. This cylindrical preheater consists of several concentric stainless sheets. Both flue gas from the combustion chamber and Polluted Air heated by flue gas flow in the spaces between the cylindrical sheets. Narrow distance strips placed between the sheets form helical rectangular ducts, through which we can achieve a counter-current flow of process fluids. A mathematical model for the calculation and/or simulation of the equipment consists of submodels of a heat exchanger and combustion chamber and the annular space between them. Based on the results of measurements on an industrial scale experimental facility, new correlations for the thermal and hydraulic calculations of the heat exchanger were ...
Nobuyuki Takegawa - One of the best experts on this subject based on the ideXlab platform.
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Evolution of mixing state of black carbon in Polluted Air from Tokyo
Geophysical Research Letters, 2007Co-Authors: Manabu Shiraiwa, Nobuyuki Takegawa, Yutaka Kondo, Yuzo Miyazaki, Nobuhiro Moteki, Donald R. BlakeAbstract:[1] The evolution of the mixing state of black carbon aerosol (BC) was investigated using a single-particle soot photometer (SP2) in Polluted Air transported from Tokyo. Ground-based measurements of aerosols and trace gases were conducted at a suburban site (Kisai) 50 km north of Tokyo during July–August 2004. The ratio of 2-pentyl nitrate (2-PeONO2) to n-pentane (n-C5H12) was used to derive the photochemical age. According to the SP2 measurement, the number fraction of thickly coated BC (Shell/Corel Ratio > ca. 2) with a core diameter of 180 nm increased at the rate of 1.9% h−1, as the photochemical clock proceeded under land-sea breeze circulation. Positive matrix factorization was applied to investigate the time-dependent contributions of different coating materials using the mass concentrations of sulfate, nitrate, and organics measured using an aerosol mass spectrometer. The main coating materials found in this study were sulfate and organics.
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Evolution of submicron organic aerosol in Polluted Air exported from Tokyo
Geophysical Research Letters, 2006Co-Authors: Nobuyuki Takegawa, Takuma Miyakawa, Yutaka Kondo, Donald R. Blake, Yugo Kanaya, Makoto Koike, M. Fukuda, Yuichi Komazaki, Yuzo Miyazaki, A. ShimonoAbstract:[1] Ground-based measurements of aerosols and trace gases were conducted at an urban site in Tokyo (Komaba) and a site 50 km to the north (Kisai) during July–August 2004. An Aerodyne aerosol mass spectrometer (AMS) was deployed at each measurement site to investigate the chemical evolution of submicron organic aerosol (OA) in Polluted Air. The mass concentrations of OA at the Kisai site were systematically higher than those at the Komaba site and were correlated with ozone under southerly conditions. The rate of increase of OA at the Kisai site is investigated using the photochemical age derived from the ratio of alkyl nitrates to their parent hydrocarbons. The OA concentrations in processed Air (age of 8–16 h) were 4–5 times larger than those in fresh emissions (age ∼ 0), suggesting that the OA concentrations can be significantly enhanced within ∼0.5 days under conditions of high photochemical activity.