Dust aerosol emission is a critical topic in agriculture, occurring either by aeolian process from bare or sparsely vegetated cropland or as fugitive emission during tilling, harvest and many other farming activities. Aerosols, which are in the case of agriculture either mineral dust, organic particles or a mixture, are known for impacting human health, cloud formation and ultimately, the earth’s climate and ecosystem. Coupled atmosphere and aerosol transport models are commonly used to study aerosol dispersion in the atmosphere, but so far, agricultural sources are under-represented. Hence, estimations of these emissions’ actual impact are still somewhat uncertain regarding their seasonality, spatial distribution and the fraction of the global aerosol load. To fill this gap, this study aims at identifying suitable approaches for modelling aeolian emissions from sparsely vegetated cropland and fugitive emissions from tilling. Fugitive emissions are challenging since they mainly depend on human activity that is not predictable, but observed events can be used as case studies. For this, a Lagrangian particle dispersion model was chosen, which can trace the trajectory of individual particles in the emitted dust plume. So the particle model “Itpas” was developed to tackle fugitive emissions and to be capable of simulating the complex turbulent mixing of dust particles inside the atmospheric boundary layer. This model was used to simulate a case study based on measured tilling emissions, showing the particle dispersion for a stable and unstable stratified boundary layer. It was shown that within a stably stratified boundary layer, the dust plume is restricted to the near-source region. In contrast, emissions in unstable boundary layers go into long-range transport. This illustrates the spatial range a single tillage operation can have an impact. Aeolian dust emissions are controlled by the wind. For cropland, the emission variability is caused mainly by the frequently changing vegetation cover. Emissions can only occur in the time between tillage and newly grown crops or during drought periods. A parametrisation based on high-resolution satellite observations of the vegetation cover was created to include this process into a model. With this, a new dust emission scheme for cropland emission was developed for the model system COSMO-MUSCAT. In a case study of a dust outbreak from cropland in Poland in 2019, the model’s ability was tested extensively on multiple spatial resolutions. Validation against satellite-measured AOD, ground-measured PM10 and the vertical profile of the PollyNET lidar in Warsaw showed an overall good agreement of the model simulation with the observations. In the framework of this thesis, one dedicated model approach was developed for both the fugitive emissions and the aeolian emissions and validated upon case studies. These approaches could help better understand agricultural dust emissions, their spatial distribution, seasonality and, ultimately, global impact.

Dust storms are one of the natural hazards, which have increased in frequency in the recent years over Sahara desert, Australia, the Arabian Desert, Turkmenistan and northern China, which have worsened during the last decade. Dust storms increase air pollution, impact on urban areas and farms as well as affecting ground and air traffic. They cause damage to human health, reduce the temperature, cause damage to communication facilities, reduce visibility which delays both road and air traffic and impact on both urban and rural areas. Thus, it is important to know the causation, movement and radiation effects of dust storms. The monitoring and forecasting of dust storms is increasing in order to help governments reduce the negative impact of these storms. Satellite remote sensing is the most common method but its use over sandy ground is still limited as the two share similar characteristics. However, satellite remote sensing using true-colour images or estimates of aerosol optical thickness (AOT) and algorithms such as the deep blue algorithm have limitations for identifying dust storms. Many researchers have studied the detection of dust storms during daytime in a number of different regions of the world including China, Australia, America, and North Africa using a variety of satellite data but fewer studies have focused on detecting dust storms at night. The key elements of this present study are to use data from the Moderate Resolution Imaging Spectroradiometers on the Terra and Aqua satellites to develop more effective automated method for detecting dust storms during both day and night and generate a MODIS dust storm database. / Libyan Centre for Remote Sensing and Space Science / Appendix A was submitted with extra data files which are not available online.

M. Tech. (Department of Metallurgical Engineering, Faculty of Engineering and Technology), Vaal University of Technology. / Dust generated during comminution of end of life printed circuit boards (PCB), typically having d80 of 212 μm, contains copper and gold up to 6.32 % and 635 g/ton, respectively. The dust particles being highly diverse in material makeup, an hydrometallurgical processing scheme able to selectively recover target values was studied. Use of mineral acids will result in multiple metal dissolution which will complicate subsequent solution treatments. Detailed characterization of the dust was first carried out, and leaching scheme were thereafter investigated to selectively recover gold and copper from the dust, in three leaching stages. Different conditions of ammonia and thiourea leaching were investigated to optimize agitation speed, reagents concentration, temperature and leaching time. The leaching kinetics of these elements from the dust under different prevailing leaching conditions were studied. Elemental composition of the dust size fractions indicates metal contents generally increase with decreasing dust particle size, down to – 53 μm size, which contains up to 635 g/ton Au, 25.43 % Fe, and 1.40 % Cu, compared to 51 g/ton Au, 3.07 % Fe and 6.32 % Cu in the 150–212 μm fraction. Thermodynamically, under oxidative ammonia leaching, zinc and copper ammine complex is feasible, yet zinc recovery is low. For 75 – 106 μm dust size, 2 M NH4OH, 17.5 M H2O2, 1 atm. pressure and 400 rpm in Parr reactor, Cu and Zn recoveries were 92 % and 50 %, while the activation energies evaluated within 283 – 313 K gave 47.39 kJ/mol and 33.12 kJ/mol. The kinetic analysis for copper leaching gave best correlation coefficient (R2) of 0.9804 when fitted into the chemical control model, and the rate constant was 4.4 x 10-3 at 313 K. The presence of base metals frustrates direct gold recovery from the dust using thiourea with sulphuric acid and hydrogen peroxide. Therefore, the residue obtained from the first stage copper leach was acid washed to remove iron and other residual base metal contents with 5 M H2SO4, at 333 K, 400 rpm for 2 hours. Recovery analysis shows that about 75-98 % Fe, 54-65 % Zn and 96-98 % Ni were recovered under this condition while Cu was less than 7 % at all PSDs; copper having been selectively removed at the first stage. Using 75 – 106 μm dust fraction, gold recovery was optimum when the acid wash residue was leached with 0.5 M thiourea (SC(NH2)2), 0.5 M sulphuric acid (H2SO4), 0.1 M hydrogen peroxide (H2O2) under 1 atm. pressure, 298 K and 400 rpm for 4 hours. The recovery was 98 % Au. Using this optimum for other size fractions, over 98 % gold was recovered from 150–212 μm, 106 – 150 μm and 75 – 106 μm dust while 71 % and 68 % Au were recovered from 53 – 75 μm and – 53 μm respectively. The lower recovery at the finest sizes can be due to the quantity of the gold contents deported in this particle size, which will require higher reagent dosage. The kinetic analysis gave best correlation coefficient (R2) of 0.99 when fitted to the chemical control leaching model. From this data, a process flowsheet was proposed to give separate streams rich in copper and gold values from the processed dust, with detailed processing parameters. This is considered a readily scalable process solution for retrieving gold and copper from PCB dust.

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No description available.

Three studies were conducted to better understand the current status of the industry and create a design process and taxonomy. Study 1 assessed current industry usage of dust control technologies and stakeholder perceptions in the concrete and masonry trades. Study 2 was similar but assessed emission control technologies in the asphalt roofing trade. Study 3 used the information from studies 1 and 2 to select a tool for further evaluation. The handheld cutoff concrete saw was chosen. An iterative design process was utilized to evaluate the saw. The design process and subsequent usability inspection engendered a taxonomy, or set of design recommendations can be applied to large handheld powered tools. / Ph. D.

An investigation into the light scattering properties of Saharan dust grains is presented. An electrodynamic trap has been used to levitate single dust particles. By adjusting the trap parameters, partial randomisation of the particle orientation has been introduced. While levitated, the particles were illuminated by a laser, and a rotating half-wave retarder enabled selection of vertically or horizontally polarized incident light. A laser diffractometer and linear photodiode array have been used to measure intensity at scattering angles between 0.5° and 177°. Combining these measurements with Fraunhofer diffraction as calculated for a range of appropriately-sized apertures allows the calculation of the phase function and degree of linear polarization. The phase functions and degree of linear polarisation for four case study particles are presented - the phase functions are found to be featureless across most of the scattering region, with none of the halo features or rainbow peaks associated with regularly shaped particles such as hexagonal columns or spheres. Particle models comprised of large numbers of facets have been constructed to resemble the levitated particles. Utilizing Gaussian random sphere methods, increasing levels of roughness have been added to the surfaces of these models. A Geometric Optics model and a related model, Ray Tracing with Diffraction on Facets, have been modified to calculate scattering on these particle reconstructions. Scattering calculations were performed on each of these reconstructions using a range of refractive indices and two rotation regimes – one where the orientations of the reconstructed particle were limited to match those observed when the particle was levitated, and one where the orientation was not limited. Qualitative comparisons are performed on the phase functions and degree of linear polarization, where it is observed that the addition of roughness to the modelled spheroids causes the computed phase functions to increasingly resemble those from the levitated particles. Limiting the orientation of the particles does not affect the scattering noticeably. The addition of a very small absorption coefficient does not change the comparisons considerably. As the absorption coefficient is increased, however, the quality of the comparisons decreases rapidly in all cases but one. The phase functions are quantitatively compared using RMS errors, and further comparison is performed using the asymmetry parameter.

Följande studie har utförts på begäran av energiföretaget Norrenergi AB, där det finns en önskan att tillförlitlighetssäkra den nuvarande driften av stofttransportsystemet tillhörande två av värmeverkets hetvattenpannor. Studien har undersökt huruvida det finns möjlighet att framförallt minska underhållskostnaderna. Studien har framförallt inriktats mot två stofttransportfläktar som vardera tillhör ett stofttransportsystem, eftersom mycket underhållsarbete lagts på de fläktarna. En jämförelse med andra liknande verk har även utförts då det visats att Norrenergi AB:s lösning av stofttransporten är ytterst ovanlig. Vidare har en analys av fläktarna utförts, vilken visade att de är underdimensionerade för systemet. Det har konstaterats utifrån genomförda SPM-, temperatur- och bullermätningar. Olika typer av lösningar på problemet har undersökts och då på en förändring av hela systemet, alternativt enbart av fläktarna eller lagren till stofttransportfläktarna. Rapporten har utmynnat i flera förslag vilka innefattar en ny systemutformning, installation av nya fläktar samt en uppgradering av det nuvarande systemet, där installation av nya fläktar rekommenderas. / This study has been carried out at the request by the energy company Norrenergi AB. It consists of an analysis on how they can reduce the maintenance regarding two dust transporting fans installed in the flue gas cleaning compartment of their thermal power plant. The study also compares what solutions other plants have regarding the dust-transport. The solution installed at Norrenergi AB was found to be rather unusual. Measurements and calculations have been performed to investigate further what have caused the high maintenance on the fans. The study looks into what upgrades are available to the entire dust transporting system. The result of the study turned into different suggestions, which includes a new configuration of the dust transporting system, and installation of new fans and also an upgrade of the existing dust transporting system. Among the suggestions the final recommendation is the alternative of installing new fans.

A dissertation submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburg, in fulfillment of the requirements for the degree of Master of Science in Engineering / Regulation 10.24 of the Minerals Act (1991) of the Republic of South Africa is applied for the purpose of preventing the development and propagation of coal-dust explosions in underground coal mines. ( Abbreviation abstract ) / AC2017

Populärvetenskaplig sammanfattning Optimering av dammbindning på Hornsgatan med NORTRIP modellen Massan av luftburna partiklar med en diameter mindre än 10 µm (PM10) är en av de tuffaste miljökvalitetsnormerna att uppnå i Sverige. PM10 kommer från flera olika källor, både naturliga som havssalt och sand, samt antropogena som vägslitage, däckslitage, bromsslitage och avgaser. En stor uppkomstkälla till PM10 i luften slitage på grund av dubbdäcksanvändning. Uppvirvlingen är som störst i mars och april efter att snön smält, temperaturen stigit och vägbanan torkat upp. För att minska PM10 halten i luften kan en dammbindande saltlösning med lägre fryspunkt än vatten läggas ut på vägbanan. I Stockholm används saltlösningen CMA (kalciummagnesiumnitrat). Det är en typ av salt med liten påverkan på den urbana miljön. Vintersäsongen 2016–2017 lades CMA ut tre gånger i veckan på några utvalda gator i Stockholm mellan november och maj. En av dessa gator är Hornsgatan, som har undersökts i denna rapport. CMA är dyrt och resurskrävande att lägga ut. För att optimera utläggningen av CMA i Stockholm har spridningsmodellen NORTRIP (non-exhaust road traffic induced particle emissions) använts. Modellen använder meteorologiska data, trafikdata och data rörande saltning, sandning och städning för att räkna ut halten PM10 som spridits till luften. Den här modellen har använts för att testa några olika dammbindande scenarion på Hornsgatan i vilka CMA har lagts ut. Det har också testats, i NORTRIP, om PM10 halten i luften skulle minska genom utläggning av vatten på vägen. Vatten lades endast ut i modellen efter 15 mars med antagandet att temperaturen inte skulle sjunka under 0 °C efter datumet ifråga. De olika scenariona var utformade för att se om det var möjligt att minimera användandet av CMA men ändå hålla nere PM10 halten i luften. Alla scenarion jämfördes med scenariot där varken CMA eller vatten lades ut för att jämföra om PM10 i luften minskade. Ett resultat visade att det var bättre att lägga ut CMA varje dag under dammiga perioder än att sikta in sig på bara de dammigaste dagarna. PM10 i luften 2016 minskade med 4,7% när de 45 dammigaste dagarna behandlades med CMA. Det kan jämföras med en minskning på 6,5% när CMA applicerades under dammiga perioder under samma år. En annan slutsats var att det ger större effekt att lägga ut CMA i mars och april än mellan november och mars. PM10 i luften 2016 minskade med 2,1% om man började lägga ut CMA 1 november som planerat, och med 1,7% om utläggningen började i slutet av februari, när den dammiga säsongen börjar. Det resulterar i att endast en liten minskning av PM10 halten uppnåddes genom att börja behandla vägbanan med CMA den 1 november istället för i slutet av februari. Att börja lägga ut CMA i slutet av februari istället för 1 november skulle minska kostnaderna betydligt för staden. Resultaten visade även att ett tunt lager vatten (0,3 mm) utlagt på vägbanan mellan ordinarie dagar för dammbindning hade en betydande effekt på PM10 halten i luften. Vid vattenutläggning mellan dagarna för CMA utläggning efter 15 mars 2016 minskar PM10 i luften under 2016 med 1,4% utöver vad den skulle minskat med om inget vatten lagts ut. Den här rapporten visar att det är möjligt att optimera utläggningen av CMA på Hornsgatan. / Abstract Optimization of dust-binding on Hornsgatan with the NORTRIP model The mass of airborne particles with a diameter smaller than 10 µm (PM10) is one of the most difficult environmental quality standards addressed in Sweden. PM10 particles originates from a variety of sources; natural, like sea salt and sand, and human made like road wear, tire wear, brake wear and exhaust. A significant source of PM10 in the air is the usage of studded tires. The suspension typically occurs in March and April when the snow layer melts, temperature rises and the streets dry. A dry street is crucial for the road dust to suspend into the air. A way to prevent road dust to suspend in to the air is spraying the road with a salt solution that does not freeze at temperatures below 0 °C. In Stockholm a dust-binding substance called CMA (Calcium Magnesium Acetate) is used. It is a of salt with minimal negative side effects on the urban environment. CMA was applied on some specific streets in Stockholm three times a week between November and May winter season 2016–2017. One of the streets that gets treated with CMA is Hornsgatan which is the topic of this paper. Dust-binding substances are expensive and time consuming to apply to the streets. To optimize the appliance of CMA in Stockholm a non-exhaust road traffic induced particle emissions (NORTRIP) model has been used. The model uses meteorological data, traffic data combined with data on salting, sanding and cleaning to calculate PM10 suspension to the air. This model has been used to test different dust-binding scenarios on Hornsgatan in which CMA was applied. It has also been tested, in NORTRIP, if spraying the road with water could have a reductive effect on PM10 in the air. Water was only added to the model after the 15th of March because it was assumed the temperature would not sink below 0 °C after this date. The different scenarios were formed to see if it was possible to minimize the usage of CMA and still keep the PM10 level low. All scenarios were compared with the scenario of not applying any CMA or water to see how much PM10 in the air was reduced. One result showed that it is better to apply CMA every day during dusty periods rather than just manage to target the dustiest days alone. PM10 in the air 2016 was reduced by 4.7% when the 45 dustiest days were treated with CMA. This could be compared to a 6.5% reduction when CMA was applied during dusty periods. Another conclusion made was that applying CMA in March and April has a greater effect then applying CMA in November, December, January and February. PM10 in the air 2016 was reduced by 2.1% if the CMA treatment started on the 1st of November as planned, and by 1.7% if the treatment started in the end of February when the dusty season starts. That means there is only a small decrease of PM10 if the appliance of CMA starts in the end of February rather than the 1st of November. Reducing the days of CMA treatment would reduce the cost significantly for the city. It was also shown that a thin layer of water (0.3 mm) applied to the street between ordinary dust-binding days has a significant effect on PM10 in the air. Adding water to the street in between days of dust-binding after the 15th of March 2016 reduced suspended PM10 2016 in the air by 1.5% beyond what it would have been reduced without the water. This paper shows that it is possible to optimize the appliance of CMA.