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941.
Machado SL Carvalho MF Gourc JP Vilar OM do Nascimento JC 《Waste management (New York, N.Y.)》2009,29(1):153-161
This paper deals with the use of simplified methods to predict methane generation in tropical landfills. Methane recovery data obtained on site as part of a research program being carried out at the Metropolitan Landfill, Salvador, Brazil, is analyzed and used to obtain field methane generation over time. Laboratory data from MSW samples of different ages are presented and discussed; and simplified procedures to estimate the methane generation potential, Lo, and the constant related to the biodegradation rate, k are applied. The first order decay method is used to fit field and laboratory results. It is demonstrated that despite the assumptions and the simplicity of the adopted laboratory procedures, the values Lo and k obtained are very close to those measured in the field, thus making this kind of analysis very attractive for first approach purposes. 相似文献
942.
Niwagaba C Nalubega M Vinnerås B Sundberg C Jönsson H 《Waste management (New York, N.Y.)》2009,29(2):585-589
In urine-diverting toilets, urine and faeces are collected separately so that nutrient content can be recycled unmixed. Faeces should be sanitized before use in agriculture fields due to the presence of possible enteric pathogens. Composting of human faeces with food waste was evaluated as a possible method for this treatment. Temperatures were monitored in three 78-L wooden compost reactors fed with faeces-to-food waste substrates (F:FW) in wet weight ratios of 1:0, 3:1 and 1:1, which were observed for approximately 20 days. To achieve temperatures higher than 15 degrees C above ambient, insulation was required for the reactors. Use of 25-mm thick styrofoam insulation around the entire exterior of the compost reactors and turning of the compost twice a week resulted in sanitizing temperatures (>or=50 degrees C) to be maintained for 8 days in the F:FW=1:1 compost and for 4 days in the F:FW=3:1 compost. In these composts, a reduction of >3 log(10) for E. coli and >4 log(10) for Enterococcus spp. was achieved. The F:FW=1:0 compost, which did not maintain >or=50 degrees C for a sufficiently long period, was not sanitized, as the counts of E. coli and Enterococcus spp. increased between days 11 and 15. This research provides useful information on the design and operation of family-size compost units for the treatment of source-separated faeces and starchy food residues, most likely available amongst the less affluent rural/urban society in Uganda. 相似文献
943.
Eleven million tonnes of waste are produced yearly by the European pulp and paper industry, of which 70% originates from the production of deinked recycled paper. Wastes are very diverse in composition and consist of rejects, different types of sludges and ashes in mills having on-site incineration treatment. The production of pulp and paper from virgin pulp generates less waste but the waste has similar properties to waste from the production of deinked pulp, although with less inorganics. Due to legislation and increased taxes, landfills are quickly being eliminated as a final destination for wastes in Europe, and incineration with energy recovery is becoming the main waste recovery method. Other options such as pyrolysis, gasification, land spreading, composting and reuse as building material are being applied, although research is still needed for optimization of the processes. Due to the large volumes of waste generated, the high moisture content of the waste and the changing waste composition as a result of process conditions, recovery methods are usually expensive and their environmental impact is still uncertain. For this reason, it is necessary to continue research on different applications of wastes, while taking into account the environmental and economic factors of these waste treatments. 相似文献
944.
K. Rajakumar V. Sarasvathy A. Thamarai Chelvan R. Chitra C. T. Vijayakumar 《Journal of Polymers and the Environment》2009,17(3):191-202
Polypropylene (PP) has achieved a dominating position and hence, their consumption increases thereby littering, which lead
to environmental pollution. Photodegradation seems to be a better choice because of naturally available sunlight as energy
source for degradation. The present work involves the study of the variation of degradation behavior of PP film during tropical
summer and winter seasons. The photodegradation is followed by Fourier transform infrared (FTIR) spectroscopic technique.
Various indices like hydroxyl, carbonyl, vinylidene, lactones, ester, carboxylic acid and crystallinity are calculated and
these values increased after a brief induction period. The variation in the mechanical properties like tensile strength and
elongation at break percentages are determined. The scanning electron microscopic (SEM) images of weathered PP showed surface
cracks when carbonyl index value increases sharply and the mechanical properties show a sudden decrease. Attempted life time
prediction using mathematical models showed that the carbonyl growth is more affected by ultraviolet (UV) and cumulative total
solar radiation for PP weathered during summer. The loss in tensile strength of PP weathered during summer is more dependent
on the average temperature and the UV portion of the total solar radiation whereas, intensity of UV radiation has profound
effect on the tensile strength of PP weathered during winter. 相似文献
945.
The Effect of Masterbatch Addition on the Mechanical, Thermal, Optical and Surface Properties of Poly(lactic acid) 总被引:1,自引:0,他引:1
F. Byrne P. G. Ward J. Kennedy N. Imaz D. Hughes D. P. Dowling 《Journal of Polymers and the Environment》2009,17(1):28-33
There has been considerable interest in the use of the biodegradable polymer poly(lactic acid) (PLA) as a replacement for
petroleum derived polymers due to ease of processability and its high mechanical strength. Other material properties have
however limited its wider application. These include its brittle properties, low impact strength and yellow tint. In an attempt
to overcome these drawbacks, PLA was blended with four commercially available additives, commonly known as masterbatches.
The effect of the addition of 1.5 wt% of the four masterbatches on the mechanical, thermal, optical and surface properties
of the polymer was evaluated. All four masterbatches had a slight negative effect on the tensile strength of PLA (3–5% reduction).
There was a four fold increase in impact resistance however with the addition of one of the masterbatches. Differential scanning
calorimetry demonstrated that this increase corresponded to a decrease in the polymer crystallinity. However there was an
associated increase in polymer haze with the addition of this masterbatch. The clarity of PLA was improved through the addition
of an optical brightener masterbatch, but the impact resistance remained low. The glass transition and melting temperatures
of PLA were not affected by the addition of the masterbatches, and no change was observed in surface energy. Some delay in
PLA degradation, in a PBS degradation medium at 50 °C, was observed due to blending with these masterbatches. 相似文献
946.
Sinkings of fishing vessels, when accompanied by human loss, are accidents which lead to a great social upheaval, especially in the local area where they occur. In order to avoid or reduce these accidents, national governments must include in their legislation for this sector the appropriate safety measures. These resources and their distribution must be assigned in accordance with the needs of the accidentality, this requiring a detailed knowledge of the concentration of accidentality of a country’s fishing sector. In this context, the aim of the present work is twofold: first, to formulate a methodology for the fishing sector of a country, allowing the inequalities in the concentration of sinking accidents to be analysed; and second, to apply this methodology to the Spanish fishing fleet. Thus, two indices are constructed per region and type of fishing, for two variables: fishermen and vessels. Results are obtained both for the concentration of accidents and the associated Lorenz curves. An increase in the inequality in the spatial and functional distribution of these accidents is verified. 相似文献
947.
Mario C.R. Vidal Paulo V.R. Carvalho Marcello S. Santos Isaac J.L. dos Santos 《Journal of Loss Prevention in the Process Industries》2009,22(4):516-527
This article aims to describe the characteristics of collective working situations in complex systems – especially those in nuclear power plants – related to common forms of cooperation, in order to improve systems resilience. In addition, we will try to detail some aspects of collective working situations, emphasizing the differences between various forms of control. The similarities between work activities (multi-addressed messages, linkage to regulation, central and peripheral information) are nonetheless exposed. We conclude by proposing a contribution to support systems design, thus facilitating cooperation in teamwork activities. 相似文献
948.
V. Vađić J. Hršak N. Kalinić M. Čačković K. Šega 《Environmental monitoring and assessment》2000,65(1-2):147-153
Hydrogen sulphide, ammonia, nitrogen dioxide, mercaptans and sulphur dioxide (H2S, NH3, NO2, R-SH, SO2) concentrations were measured at the location in the vicinity of the waste dump to determine the air pollution level of these pollutants prior to the operation of the Mobile Thermal Treatment Plant. Samples were collected over one year period. Seasonal differences, and the influence of meteorological parameters (temperature, relative humidity, pressure and wind direction) on the air pollution levels were studied. Results show relatively low concentrations of H2S, NO2, R-SH and SO2, while NH3 levels were higher compared to the guideline values. Good weather conditions (high air pressure and low relative humidity) are connected to long range transport of NO2, while higher temperatures result in elevated NH3 and R-SH concentrations. Because of the predominant northeast wind direction (the same as the waste dump direction), the contribution of air pollution from the direction of the waste dump at the measuring site is significant, but that does not necessarily mean that the pollutants originated from that source. 相似文献
949.
Past changes and possible future variations in the nature of extreme precipitation and flood events in Central Europe and
the Alpine region are examined from a physical standpoint. An overview is given of the following key contributory physical
processes: (1) the variability of the large-scale atmospheric flow and the associated changes of the North-Atlantic storm
track; (2) the feedback process between climate warming and the water cycle, and in particular the potential for more frequent
heavy precipitation events; and (3) the catchment-scale hydrological processes associated with variations in major river flooding
events and that are related to land-use changes, river training measures, and shifts in the proportion of rain to snowfall.
In this context an account is provided of the possible future forecasting and warning methodologies based upon high-resolution
weather prediction and runoff models. Also consideration is given to the detectability of past (future) changes in observed
(modeled) extreme events. It is shown that their rarity and natural fluctuation largely impedes a detection of systematic
variations. These effects restrict trend analysis of such events to return periods of below a few months. An illustration
using daily precipitation from the Swiss Alps does yield evidence for pronounced trends of intense precipitation events (return
period 30 days), while trends of stronger event classes are not detectable (but nevertheless can not be excluded). The small
detection probability for extreme events limits possible mitigation of future damage costs through an abatement of climate
change alone, and points to the desirability of developing improved early forecasting/warning systems as an additional no-regret
strategy.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
950.
Ali-Khodja H Belaala A Demmane-Debbih W Habbas B Boumagoura N 《Environmental monitoring and assessment》2008,138(1-3):219-231
Total suspended particulate matter and deposition fluxes of particles were investigated in the town of Didouche Mourad which
is located 13 km north of Constantine. Samples of air particulate matter were collected at one site located in the heart of
the town and situated 3 km north of a cement plant. Samples were collected from 2 November 2002 to 28 April 2003 every 3 days
using a high volume air sampler. Sampling intervals were 24 h in all cases. During the same period, samples of dust fallout
were collected at the same site. Samples were collected at 30-day intervals. Lead, chromium, manganese, nickel, copper, cobalt
and cadmium deposition fluxes were measured and both the soluble and insoluble fractions were determined. Furthermore, the
information gathered by this study was correlated with the corresponding hourly weather data provided by a weather station
installed at the study station. The possible sources for dust and trace metals were analyzed by comparing average contributions
of wind aspects to the concentrations and depositions of mass and chemical species with the average frequencies of wind direction.
The mean concentration was 300 μg/m3. The average dust deposition rate through the period of study was 221 mg/(m2.day). Results indicate that anthropogenic sources contribute greatly to trace elements. An exposure assessment to the heavy
metals taking into account the inhalation route and soil dust ingestion was carried out and allowed direct comparison of trace
metal intakes via these routes. 相似文献