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71.
CFD Prediction of Air Quality in the Area between Two City Vehicular Tunnels Considering Moving Cars
Concentration fields of different pollutants that spread outside two roadtunnels predicted with a CFD code will be presented. The solution domain represents the city area located between two tunnel outlets – tunnel Strahov and tunnel Mrazovka in Prague. The vicinity of both tunnels is a heavily built up area with tall buildings forming typical street canyons. The CFD modelling predicts the situation after the tunnel Mrazovka will be finished and traffic will increase considerably between both tunnels. Namely, an interest was given to the prediction of dispersion of emissions leaving both tunnel and the area touched by the traffic. For the CFD predictions, a method previously developed for moving vehicles was used. The method uses combination of Eulerian and Lagrangian approaches to moving objects and is capable of modeling different speeds and traffic rates of cars as well as traffic-induced turbulence. Influence of several meteorological parameters was studied, namely wind speed and direction and traffic parameters, like traffic rates and speed of cars. The method separates contributions from different sources to the total concentration field, namely from background, tunnel outlet and roadway. Results are presented in the form of horizontal and vertical concentration fields of NOx. 相似文献
72.
Gemma Molins María Dolores Álvarez Núria Garrido Jorge Macanás Fernando Carrillo 《Journal of Polymers and the Environment》2018,26(3):873-884
The aim of this study is to analyse the environmental impacts (EIs) of the process of preparation of new biocomposite materials obtained from polylactide (PLA) and chicken feathers (CFs). Two CFs stabilization methods and different percentages of CFs have been studied. The EIs of these new composites were compared to the impact of virgin PLA. Cradle-to-gate life cycle inventories were assessed for 0–35% v/v of CFs in a CFs/PLA biocomposite. Two CFs stabilization processes, autoclave and surfactant, were tested and compared with the aim to prioritize one of them from the environmental point of view. A composite plate of 184?×?184?×?2.2 mm3 was defined as the functional unit. Autoclave stabilization process exhibited lower environmental impact compared with surfactant stabilization process mainly due to both the lower requirements of electricity and water and the reduced pollution loads of the generated wastewater. Thus, the autoclave process was selected as the standard method when comparing the EIs of the proposed CFs/PLA biocomposites. In this sense, the addition of CFs to PLA matrix proportionally reduces all the EIs compared to pure PLA due to the replacement of PLA with CFs. This behaviour can be explained because the PLA production accounts for the 99% of the impact of the biocomposite. Consequently, CFs conveniently stabilized might be an alternative raw material to prepare CFs/PLA biocomposites with less environmental impact compared to pure PLA. 相似文献
73.
Baked Foams Based on Cassava Starch Coated with Polyvinyl Alcohol with a Higher Degree of Hydrolysis
Fabíola Azanha de Carvalho Ana Paula Bilck Fabio Yamashita Suzana Mali 《Journal of Polymers and the Environment》2018,26(4):1445-1452
The aims of this work were to produce trays based on cassava starch, coated with polyvinyl alcohol (PVA) with a higher degree of hydrolysis (98%), and to study the effects of the coating on the mechanical and water sorption properties of the trays. Two types of PVA were tested: SELVOL? 325 (degree of polymerization?=?1000–1500) and SELVOL? 107 (degree of polymerization?=?350–650). A decrease in the water absorption capacity of 50% was observed when the coated samples were compared with the control sample after 30 min of immersion in water. It was observed in both coated samples a reduction of the initial rate of water adsorption sorption and a decrease in hydrophilicity compared with the control sample. Tensile strength and elongation were increased with application of the coatings. The use of the two types of PVA resulted in materials with similar mechanical and water sorption properties. 相似文献
74.
Jiří Pšeja Josef Hrnčiřík Jan Kupec Hana Charvátová Petr Hruzík Michael Tupý 《Journal of Polymers and the Environment》2006,14(3):231-237
Biodegradability testing was performed in an aqueous environment under anaerobic conditions after inoculation with digested sludge from municipal wastewater treatment plant. In cross-linking with 1,2:3,4-diepoxybutane in limits 0.8–9.1% weight, biodegradability degree decreased from 76.8 to 62.2%; when 1,2:7,8 diepoxyoctane in quantities 1.1–13.2% weight was used, biodegradability degree dropped more prominently – from 72.3 to 22.8%. There is obviously a direct connection between growing cross-link degree (assessed by so-called fixation index) and decreasing readiness to biodegradation, apparently owing to build-up of a network forming an obstacle to access of micro-organisms and enzymes. 相似文献
75.
Nada Horvatinčić José Luis Briansó Bogomil Obelić Jadranka Barešić Ines Krajcar Bronić 《Water, Air, & Soil Pollution: Focus》2006,6(5-6):475-485
The process of eutrophication in form of intense plant growth has been observed in some lakes and water streams at the Plitvice
Lakes National Park in central Croatia. Here we investigate whether this phenomenon is a consequence of anthropogenic pollution
or due to naturally produced organic matter in the lakes. We applied chemical analysis of water at two springs and four lakes
(nutrients, dissolved organic carbon (DOC), trace elements) and measurements of surface lake sediments (mineral and organic
fraction analyses, trace elements) in four different lakes/five sites. The chemical composition of water does not indicate
recent anthropogenic pollution of water because the concentrations of most trace elements are below detection limits. The
concentrations of DOC and nutrients are slightly higher in the area of increased eutrophication-plant growth. Also the content
of organic matter in the sediment is at the highest level in areas with highest C/N ratio indicating that the organic fraction of this sediment is mainly of terrestrial origin. There is no significant difference
among the trace element concentration in the upper segment of all cores, deposited approximately during last 50 years when
higher anthropogenic influence is expected due to development and touristic activity, and the lower part of the cores, corresponding
to the period approximately 100–200 years before present. The content of trace elements and organic matter in sediments decreases
from the uppermost lake downstream. According to our results there is no indication of recent anthropogenic pollution in water
and sediment. Higher concentrations of DOC in water as well as phosphorus and some other elements in the lake sediment can
be a consequence of input of natural organic matter to the lake water. 相似文献
76.
The size and isotopic behavior of sulfur pools in210Pb-dated peat cores were investigated to obtain aninsight into retention mechanisms of pollutant S in twomountain-top peatlands of the Northern Czech Republic, CentralEurope. The bogs were situated 40 km apart in an area whichbetween the years 1985 and 1995 received as much as 130 kg Sha-1 yr-1 from the atmosphere. Vertical peataccretion was faster at Pod Jelení horou (JH) than atVelký moál (VM). Organic carbon-bonded S was themost abundant sulfur pool, constituting 77 and 65 wt. % at JHand VM, respectively. At JH both the S concentration maximumand the highest annual S deposition rate were displaceddownward by more than 20 years (from 1987 to the 1960s)indicating that the buried S is vertically mobile. At VM the Sconcentration was the highest in the topmost 2-cm section eventhough atmospheric S deposition peaked in 1987. Differentmechanisms of S isotope redistribution prevailed in thetopmost peat layers at JH, where a negative 34Sshift occurred, and at VM, where a positive 34Sshift occurred. Bacterial sulfate reduction was responsiblefor the negative 34S shift at JH. One possibleexplanation of the positive 34S shift at VM isrelease of 32S-enriched products of mineralization duringpeat diagenesis. There was a strong positive correlationbetween the abundance of total and pyrite S along the profiles.The presence of pyrite S at VM (526 ± 60 ppm) suggestedthat even at VM bacterial sulfate reduction occurred. Ananaerobic incubation of JH peat indicated sulfate reductionrate of 600 nmol g-1 day-1. The turnover times forinorganic S pools were shorter than for the organic S pools.Cumulative S contents in the Czech peat bogs were found to besignificantly lower than in similar sites in the NortheasternU.S., even though the atmospheric S inputs were more thanthree times higher at the Czech sites. Possible causes of suchdiscrepancy are discussed. 相似文献
77.
Caroline Michel Marie-Thérèse Giudici-Orticoni Frauke Baymann Mireille Bruschi 《Water, Air, & Soil Pollution: Focus》2003,3(3):161-169
The treatment of soils and ground waters polluted by heavy metals is of economical and environmental interest. Reduction of Cr(VI) to the less toxic Cr(III) associated to its precipitation is a potentially useful process for bioremediation. In order to develop ecological processes using micro-organisms, we have compared various sulfate-reducing bacteria for enzymatic reduction of chromate. The best Cr(VI) reductase activity was obtained with Desulfomicrobium norvegicum. Despite morphological changes induced by the presence of chromate, this strain can grow in the presence of up to 500 M Cr(VI) and can decontaminate waters polluted by Cr(VI) when seeded in bioreactors. We have demonstrated the ability of several metalloenzymes (cytochromes c
3 and hydrogenases) to reduce chromate. Biophysical investigations of the chromate/protein interaction in order to get further informations on the mechanism of metal reduction by cytochromes c
3 are under the way. 相似文献
78.
de Guzmán Báez A Villoria Sáez P del Río Merino M García Navarro J 《Waste management (New York, N.Y.)》2012,32(5):920-924
In the last years, the European Union (EU) has been focused on the reduction of construction and demolition (C&D) waste. Specifically, in 2006, Spain generated roughly 47million tons of C&D waste, of which only 13.6% was recycled. This situation has lead to the drawing up of many regulations on C&D waste during the past years forcing EU countries to include new measures for waste prevention and recycling. Among these measures, the mandatory obligation to quantify the C&D waste expected to be originated during a construction project is mandated. However, limited data is available on civil engineering projects. Therefore, the aim of this research study is to improve C&D waste management in railway projects, by developing a model for C&D waste quantification. For this purpose, we develop two equations which estimate in advance the amount, both in weight and volume, of the C&D waste likely to be generated in railway construction projects, including the category of C&D waste generated for the entire project. 相似文献
79.
Correlation analysis between sulphate content and leaching of sulphates in recycled aggregates from construction and demolition wastes 总被引:1,自引:0,他引:1
Barbudo A Galvín AP Agrela F Ayuso J Jiménez JR 《Waste management (New York, N.Y.)》2012,32(6):1229-1235
In some recycled aggregates applications, such as component of new concrete or roads, the total content of soluble sulphates should be measured and controlled. Restrictions are usually motivated by the resistance or stability of the new structure, and in most cases, structural concerns can be remedied by the use of techniques such as sulphur-resistant cements. However, environmental risk assessment from recycling and reuse construction products is often forgotten. The purpose of this study is to analyse the content of soluble sulphate on eleven recycled aggregates and six samples prepared in laboratory by the addition of different gypsum percentages. As points of reference, two natural aggregates were tested. An analysis of the content of the leachable amount of heavy metals regulated by European regulation was included. As a result, the correlation between solubility and leachability data allow suggest a limiting gypsum amount of 4.4% on recycled aggregates. This limit satisfies EU Landfill Directive criteria, which is currently used as reference by public Spanish Government for recycled aggregates in construction works. 相似文献
80.
Effect of aeration rate and moisture content on the emissions of selected VOCs during municipal solid waste composting 总被引:11,自引:0,他引:11
M. Delgado-Rodríguez M. Ruiz-Montoya I. Giraldez R. López E. Madejón M. J. Díaz 《Journal of Material Cycles and Waste Management》2012,14(4):371-378
The influence of the industrial control composting conditions (aeration 0.005–0.300?Lair?kg?1 and moisture 40–70?%) of municipal solid waste on the composition of the selected compound emitted (limonene, β-pinene, 2-butanone, undecane, phenol, toluene, dimethyl sulfide, dimethyl disulfide) was studied. The highest emissions of volatile organic compounds (VOCs) were observed in the early stages of the processes. At the end of the process, low concentrations of the emitted compounds were found. Aeration rate had a strong effect on emissions. High aeration rate (0.300?Lair?kg?1?min?1) caused normally high emissions of all selected compounds whereas low aeration rates (0.05?Lair?kg?1?min?1) could cause anaerobiosis problems and generation of organic sulphur compounds. We observed that the effect of the moisture upon the emitted concentrations varied depending on the studied compound. 相似文献