| 1. |
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| 2. |
- Jassim, Hassanean, 1978-, et al.
(författare)
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Determining the environmental impact of material hauling with wheel loaders during earthmoving operations
- 2019
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Ingår i: Journal of the Air and Waste Management Association. - : Taylor & Francis. - 1096-2247 .- 2162-2906. ; 69:10, s. 1195-1214
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Tidskriftsartikel (refereegranskat)abstract
- A method has been developed to estimate the environmental impact of wheel loaders used in earthmoving operations. The impact is evaluated in terms of energy use and emissions of air pollutants (CO2, CO, NOx, CH4, VOC, and PM) based on the fuel consumption per cubic meter of hauled material. In addition, the effects of selected operational factors on emissions during earthmoving activities were investigated to provide better guidance for practitioners during the early planning stage of construction projects. The relationships between six independent parameters relating to wheel loaders and jobsite conditions (namely loader utilization rates, loading time, bucket payload, horsepower, load factor, and server capacity) were analyzed using artificial neural networks, machine performance data from manufacturer’s handbooks, and discrete event simulations of selected earthmoving scenarios. A sensitivity analysis showed that the load factor is the largest contributor to air pollutant emissions, and that the best way to minimize environmental impact is to maximize the wheel loaders’ effective utilization rates. The new method will enable planners and contractors to accurately assess the environmental impact of wheel loaders and/or hauling activities during earthmoving operations in the early stages of construction projects.Implications: There is an urgent need for effective ways of benchmarking and mitigating emissions due to construction operations, and particularly those due to construction equipment, during the pre-construction phase of construction projects. Artificial Neural Networks (ANN) are shown to be powerful tools for analyzing the complex relationships that determine the environmental impact of construction operations and for developing simple models that can be used in the early stages of project planning to select machine configurations and work plans that minimize emissions and energy consumption. Using such a model, it is shown that the fuel consumption and emissions of wheel loaders are primarily determined by their engine load, utilization rate, and bucket payload. Moreover, project planners can minimize the environmental impact of wheel loader operations by selecting work plans and equipment configurations that minimize wheel loaders’ idle time and avoid bucket payloads that exceed the upper limits specified by the equipment manufacturer.
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| 3. |
- Kinobe, Joel, et al.
(författare)
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Mapping out the solid waste generation and collection models: The case of Kampala City
- 2015
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Ingår i: Journal of the Air and Waste Management Association. - : Informa UK Limited. - 1096-2247 .- 2162-2906. ; 65, s. 197-205
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a mapping of the waste collection systems in Kampala city, using geographical information system (GIS) ArcGIS mapping software. It discusses the existing models of waste collection to the final disposal destinations. It was found that food and yard wastes constitute 92.7% of the waste generated in Kampala. Recyclables and other special wastes constitute only 7.3% of the total waste, mainly because of the increased level of reuse and recycling activities. The generation rate of solid wastes was on average, 582, 169, 105, and 90 tons/day from poor areas, upscale wealthier areas, business centers, and market areas respectively. This tonnage of waste was collected, transported, and disposed of at the city landfill. The study found that in total, residential areas of poor people generate more waste than other categories stated earlier, mainly because of their large populations. In total, there were 133 unofficial temporary storage sites acknowledged by Kampala Capital City Authority (KCCA) but not formally designated, 59 illegal dump sites, and 35 officially recognized temporary waste storage locations. This paper presents large-scale data that can help with understanding the collection models and their influence on solid waste management in Kampala city, which could be used for similar cities in developing countries.
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| 4. |
- Komakech, Allan, et al.
(författare)
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Characterization of municipal waste in Kampala, Uganda
- 2014
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Ingår i: Journal of the Air and Waste Management Association. - : Taylor & Francis. - 1096-2247 .- 2162-2906. ; 64:3, s. 340-348
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Tidskriftsartikel (refereegranskat)abstract
- In Kampala, Uganda, about 28,000 tons of waste is collected and delivered to a landfill every month. Kampala Capital City Authority (KCCA) records show that this represents approximately 40% of the waste generated in the city. The remaining uncollected waste is normally dumped in unauthorized sites, causing health and environmental problems. However, the organic fraction of domestic waste can provide an opportunity to improve livelihoods and incomes through fertilizer and energy production. This study characterized the municipal waste generated in Kampala and delivered to Kiteezi landfill between July 2011 and June 2012, that is, covering the dry and wet months. On each sampling day, waste was randomly selected from five trucks, sorted and weighed into different physical fractions. Samples of the organic waste from each truck were analyzed for total solids, major nutrients, and energy content. During the wet months, the waste consisted of 88.5% organics, 3.8% soft plastics, 2.8% hard plastics, 2.2% paper, 0.9% glass, 0.7% textiles and leather, 0.2% metals, and 1.0% others. During the dry months, the waste consisted of 94.8% organics, 2.4% soft plastics, 1.0% hard plastics, 0.7% papers, 0.3% glass, 0.3% textile and leather, 0.1% metals, and 0.3% others. The organic waste on average had a moisture content of 71.1% and contained 1.89% nitrogen, 0.27% phosphorus, and 1.95% potassium. The waste had an average gross energy content of 17.3 MJ/kg. It was concluded that the organic waste generated can be a suitable source of some plant nutrients that are useful especially in urban agriculture. Implications: The result of the waste characterization in Kampala was found to be significantly different from that obtained for other Sub-Saharan African (SSA) cities, showing that studies assuming average values for the waste fractions are likely to result in erroneous results. Furthermore, no reduction in organic fraction of the waste was noticed when compared with a study done two decades ago in spite of greatly improved economic status of Kampala city, a finding that is not in agreement with several other similar studies done for other SSA cities.
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| 5. |
- Krecl, Patricia, et al.
(författare)
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Spatiotemporal Variability of Light-Absorbing Carbon Concentration in a Residential Area Impacted by Woodsmoke
- 2010
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Ingår i: Journal of the Air & Waste Management Association. - : Informa UK Limited. - 1047-3289 .- 1096-2247 .- 2162-2906. ; 60:3, s. 356-368
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Tidskriftsartikel (refereegranskat)abstract
- Residential wood combustion (RWC) is responsible for 33% of the total carbon mass emitted in Europe. With the new European targets to increase the use of renewable energy, there is a growing concern that the population exposure to woodsmoke will also increase. This study investigates observed and simulated light-absorbing carbon mass (M-LAC) concentrations in a residential neighborhood (Lycksele, Sweden) where RWC is a major air pollution source during winter. The measurement analysis included descriptive statistics, correlation coefficient, coefficient of divergence, linear regression, concentration roses, diurnal pattern, and weekend versus weekday concentration ratios. Hourly RWC and road traffic contributions to M-LAC were simulated with a Gaussian dispersion model to assess whether the model was able to mimic the observations. Hourly mean and standard deviation concentrations measured at six sites ranged from 0.58 to 0.74 mu g m(-3) and from 0.59 to 0.79 mu g m(-3), respectively. The temporal and spatial variability decreased with increasing averaging time. Low-wind periods with relatively high M-LAC concentrations correlated more strongly than high-wind periods with low concentrations. On average, the model overestimated the observations by 3- to 5-fold and explained less than 10% of the measured hourly variability at all sites. Large residual concentrations were associated with weak winds and relatively high M-LAC loadings. The explanation of the observed variability increased to 31-45% when daily mean concentrations were compared. When the contribution from the boilers within the neighborhood was excluded from the simulations, the model overestimation decreased to 16-71%. When assessing the exposure to light-absorbing carbon particles using this type of model, the authors suggest using a longer averaging period (i.e., daily concentrations) in a larger area with an updated and very detailed emission inventory.
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| 6. |
- Pirjola, Liisa, et al.
(författare)
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Road Dust Emissions from Paved Roads Measured Using Different Mobile Systems
- 2010
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Ingår i: Journal of the Air & Waste Management Association. - : Informa UK Limited. - 1047-3289 .- 1096-2247 .- 2162-2906. ; 60:12, s. 1422-1433
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Tidskriftsartikel (refereegranskat)abstract
- Very few real-world measurements of road dust suspension have been performed to date. This study compares two different techniques (referred to as Sniffer and Emma) to measure road dust emissions. The main differences between the systems are the construction of the inlet, different instruments for recording particulate matter (PM) levels, and different loads on the wheel axes (the weight of Sniffer was much higher than that of Emma). Both systems showed substantial small-scale variations of emission levels along the road, likely depending on-road surface conditions. The variations observed correlated quite well, and the discrepancies are likely a result of variations in dust load on the road surface perpendicular to the driving direction that cause variations in the measurements depending on slightly different paths driven by the two vehicles. Both systems showed a substantial influence on the emission levels depending on the type of tire used. The summer tire showed much lower suspension than the winter tires (one nonstudded and one studded). However, the relative importance of the nonstudded versus studded tire was rather different. For the ratio of studded/nonstudded, Emma shows higher values on all road sections compared with Sniffer. Both techniques showed increased emission levels with increasing vehicle speed. When the speed increased from 50 to 80 km hrthe relative concentrations increased by 30-170% depending on the tire type and dust load. However, for road sections that were very dirty, Sniffer showed a much higher relative increase in the emission level with the nonstudded tire. Sniffer's absolute concentrations were mostly higher than Emma's. Possible reasons for the differences are discussed in the paper. Both systems can be used for studying relative road dust emissions and for designing air quality management strategies.
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| 7. |
- Sharma, Prabhakar, 1976-, et al.
(författare)
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Gas dispersion and immobile gas volume in solid and porous particle biofilter materials at low air flow velocities
- 2010
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Ingår i: Journal of the air & waste management association. - : Informa UK Limited. - 1047-3289 .- 1096-2247 .- 2162-2906. ; 60:7, s. 830-837
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Tidskriftsartikel (refereegranskat)abstract
- Gas-phase dispersion in granular biofilter materials with awide range of particle sizes was investigated using atmosphericair and nitrogen as tracer gases. Two types ofmaterials were used: (1) light extended clay aggregates(LECA), consisting of highly porous particles, and (2)gravel, consisting of solid particles. LECA is a commercialmaterial that is used for insulation, as a soil conditioner,and as a carrier material in biofilters for air cleaning. Thesetwo materials were selected to have approximately thesame particle shape. Column gas transport experimentswere conducted for both materials using different meanparticle diameters, different particle size ranges, and differentgas flow velocities. Measured breakthrough curveswere modeled using the advection-dispersion equationmodified for mass transfer between mobile and immobilegas phases. The results showed that gas dispersivity increasedwith increasing mean particle diameter for LECAbut was independent of mean particle diameter for gravel.Gas dispersivity also increased with increasing particlesize range for both media. Dispersivities in LECA weregenerally higher than for gravel. The mobile gas contentin both materials increased with increasing gas flow velocitybut it did not show any strong dependency onmean particle diameter or particle size range. The relativefraction of mobile gas compared with total porosity washighest for gravel and lowest for LECA likely because of itshigh internal porosity.
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| 8. |
- Sharma, Prabhakar, 1976-, et al.
(författare)
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Gaseous Oxygen Uptake in Porous Media at Different Moisture Contents and Airflow Velocities
- 2009
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Ingår i: Journal of the Air & Waste Management Association. - : Informa UK Limited. - 1047-3289 .- 1096-2247 .- 2162-2906. ; 59:6, s. 676-682
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Tidskriftsartikel (refereegranskat)abstract
- The presence and distribution of water in the pore space isa critical factor for flow and transport of gases throughunsaturated porous media. The water content also affectsthe biological activity necessary for treatment of pollutedgas streams in biofilters. In this research, microbial activityand quantity of inactive volume in a porous mediumas a function of moisture content and gas flow rate wereinvestigated. Yard waste compost was used as a test medium,and oxygen uptake rate measurements were used toquantify microbial activity and effective active compostvolume using batch and column flow-through systems.Compost water contents were varied from air-dry to fieldcapacity and gas flows ranged from 0.2 to 2 L min1. Theresults showed that overall microbial activity and therelative fraction of active compost medium volume increasedwith airflow velocity for all levels of water contentup to a certain flow rate above which the oxygen uptakerate assumed a constant value independent of gas flow.The actual value of the maximum oxygen uptake rate wascontrolled by the water content. The oxygen uptake ratealso increased with increasing water content and reacheda maximum between 42 and 48% volumetric water content,above which it decreased, again likely because offormation of inactive zones in the compost medium.Overall, maximum possible oxygen uptake rate as a functionof gas flow rate across all water contents and gas flowscould be approximated by a linear expression. The relativefraction of active volume also increased with gas flowrate and reached approximately 80% for the highest gasflows used.
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| 9. |
- van der Gon, Hugo A. C. Denier, et al.
(författare)
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The Policy Relevance of Wear Emissions from Road Transport, Now and in the FutureAn International Workshop Report and Consensus Statement
- 2013
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Ingår i: Journal of the Air and Waste Management. - : Informa UK Limited. - 1096-2247 .- 2162-2906. ; 63:2, s. 136-149
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Forskningsöversikt (refereegranskat)abstract
- Road transport emissions are a major contributor to ambient particulate matter concentrations and have been associated with adverse health effects. Therefore, these emissions are targeted through increasingly stringent European emission standards. These policies succeed in reducing exhaust emissions, but do not address nonexhaust emissions from brake wear, tire wear, road wear, and suspension in air of road dust. Is this a problem? To what extent do nonexhaust emissions contribute to ambient concentrations of PM10 or PM2.5? In the near future, wear emissions may dominate the remaining traffic-related PM10 emissions in Europe, mostly due to the steep decrease in PM exhaust emissions. This underlines the need to determine the relevance of the wear emissions as a contribution to the existing ambient PM concentrations, and the need to assess the health risks related to wear particles, which has not yet received much attention. During a workshop in 2011, available knowledge was reported and evaluated so as to draw conclusions on the relevance of traffic-related wear emissions for air quality policy development. On the basis of available evidence, which is briefly presented in this paper, it was concluded that nonexhaust emissions and in particular suspension in air of road dust are major contributors to exceedances at street locations of the PM10 air quality standards in various European cities. Furthermore, wear-related PM emissions that contain high concentrations of metals may (despite their limited contribution to the mass of nonexhaust emissions) cause significant health risks for the population, especially those living near intensely trafficked locations. To quantify the existing health risks, targeted research is required on wear emissions, their dispersion in urban areas, population exposure, and its effects on health. Such information will be crucial for environmental policymakers as an input for discussions on the need to develop control strategies. Implications: Road transport particulate matter (PM) emissions are associated with adverse health effects. Stringent policies succeed in reducing the exhaust PM emissions, but do not address nonexhaust emissions from brake wear, tire wear, road wear, and suspension in air of road dust. In the near future the nonexhaust emissions will dominate the road transport PM emissions. Based on the limited available evidence, it is argued that dedicated research is required on nonexhaust emissions and dispersion to urban areas from both an air quality and a public health perspective. The implicated message to regulators and policy makers is that road transport emissions continue to be an issue for health and air quality, despite the encouraging rapid decrease of tailpipe exhaust emissions. Supplemental Materials: Supplemental materials are available for this paper. Go to the publisher's online edition of the Journal of the Air & Waste Management Association.
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| 10. |
- Winnes, Hulda, 1975, et al.
(författare)
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Particle Emissions from Ships: Dependence on Fuel Type
- 2009
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Ingår i: Journal of the Air & Waste Management Association. - : Informa UK Limited. - 1047-3289 .- 1096-2247 .- 2162-2906. ; 59:12, s. 1391-1398
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the results of field emission measurements that have been carried out on the 4500-kW four-stroke main engine on-board a product tanker. Two fuel qualities-heavy fuel oil (HFO) and marine gas oil (MGO)-have been tested on the same engine for comparable load settings. A fuel switch within the marine sector is approaching and the aim of this study is to draw initial conclusions on the subsequent effects on ship exhaust gas composition and emission factors with a focus on particles. Measurements on exhaust gas concentrations of carbon dioxide (CO2), carbon monoxide (CO), nitrogen oxides (NOx), sulfur dioxide (SO2), total hydrocarbons (HCs), and particulate matter (PM) were conducted. The gases, except SO2, did not show any major differences between the fuels. Specific PM emissions were generally higher for HFO than for MGO; however, for the smallest size-fraction measured containing particles 0.300.40 mu m in diameter, the opposite is observed. This finding emphasizes that to minimize negative health effects of particles from ships, further regulation may be needed to reduce small-sized particles; a fuel shift to low sulfur fuel alone does not seem to accomplish this reduction. The average of this and previously published data from on-board studies on particle emissions from ships results in emissions factors of 0.33 and 1.34 g/kWh for marine distillate oil (MDO) and HFO, respectively. Accounting for 1 standard deviation in each direction from the average values gives a range of 0.18-0.48 g/kWh for MDO and 0.56-2.12 g/kWh for HFO.
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