Bulk chemical analysis of a combined municipal solid waste (MSW) bottom and fly ash from one facility showed most elements enriched over average soil abundances. Eleven minerals were identified using powder X-ray diffraction (XRD). Standard additions using XRD gave the following weight % minerals (±2σ): gypsum, 1.8 ± 1.9; hematite, 3.7 ± 1.7; quartz, 2.3 ± 1.0; spinel, approximately 3.5; halite, 0.5 ± 0.4; calcite 3.5 ± 1.9; rutile, 1.1 ± 1.3. Mullite, sylvite, anhydrite, and wüstite were also identified. The ash contained 18% minerals, 9% structural and adsorbed water, and 72% glass. Chemical sequential extraction showed that most Cr is present in phases resistant to chemical weathering, while significant Cd and Pb are sequestered in acid soluble (carbonate) phases. Little of these toxic trace metals are water soluble or in exchangeable surface sites. Batch reactors experiments showed that ash-water solutions were dominated by ions released by soluble salts. Three types of reactions are identified. 1) After rapid exhaustion of soluble salts, sodium and potassium exhibited nearly steady state behavior due to slow release of ions from less-soluble minerals and glasses. 2) Calcium and sulfate concentrations are controlled by either gypsum or anhydrite equilibrium after a few hours. Iron, aluminum, and manganese concentrations rapidly equilibrate with respect to hydroxide or oxide solid phases. 3) Silicon clearly shows temperature dependent kinetic behavior, but its rate of release into solution is slowed by back-reaction of a secondary silicate phase. Calculation of the CIPW normative minerals for MSW ash showed it to be analogous to a tholeiitic basalt. Over the long term, the concentrations of elements in MSW ash will continue to change and can be predicted by Goldschmidt's concept of ionic potential, and mineralogical changes can be predicted based on weathering of basalts. Comparisons of literature values showed that field MSW ash leachates contained higher concentrations of soluble salts and lower concentrations of magnesium, iron, zinc, copper, and nickel than uncombusted refuse leachates. Comparison of chromium, cadmium, lead, and arsenic concentrations did not clearly delineate which leachate contains more of these elements. / Ph. D.

The separate land disposal of coal refuse and fly ash presents difficulties throughout the Appalachian region, both in terms of disposal costs per acre and in terms of its potential environmental impacts on soil, ground water, revegetation, and slope stability. The purpose of this study was to determine how fly ash addition to coal refuse would impact on certain geotechnical properties of the refuse disposal piles, and whether the refuse-fly ash blends would be suitable as co-disposed materials. Accordingly, the compaction, permeability and shear strength characteristics of the refuse-fly ash blends were experimentally determined for varying fly ash percentages. The compaction test results indicated that, with increasing fly ash, the maximum dry density of these blends marginally decreased. The permeability test results showed that the permeability of the test specimens progressively decreased with the increase in fly ash. The shear strength results demonstrated that the addition of fly ash did not significantly influence the shear strength of the refuse. The critical factor of safety determined during slope stability analysis revealed that the tested slope geometries were stable for long term, drained conditions (using the STABGM computer program). The volume change analysis determined that there was a minimal expansion in the volume of refuse when it was blended with fly ash. However, it may be noted that all the stated results depend on a number offactors, including the nature of the refuse and fly ash used. Therefore, these findings would be specific to bulk blends of coal refuse and fly ash only. In general, this study indicates that fly ash can be beneficially reused with respect to the geotechnical properties evaluated. Co-disposal of fly ash and coal refuse may be a reasonable alternative to present disposal methods. / Master of Science

The mango tree is one the important sources of income in the rural economy of Senegal. However, mango producers in Ziguinchor are facing fruit fly infestations leading to important losses in income. The aim of this study is to measure the impact of the losses encountered by mango farmers in Ziguinchor over three years 2012, 2013, and 2014 and conduct an econometric study to examine household characteristics associated with high level of losses. At the household level, the total yearly losses on average from fruit fly infestations represent 17.09 % of the average total household income in Ziguinchor (Casamance). The losses associated with variability of production are much smaller than losses from decreases of average yield. Furthermore, the results show that the number of hectares, level production, and use of Keitt varieties are three factors statistically significant, with a significant positive influence on losses from infestation. The use of fruit fly control technologies does not appear to significantly reduce losses. / Master of Science

Most Appalachian coal refuse materials contain significant amounts of pyritic sulfur and are likely to produce acid mine drainage (AMD). A column technique was designed and implemented to evaluate the effects of various AMD mitigation treatments including fly ash, topsoil, lime, and rock-P. Two types of fly ash were tested, one at four blending rates, the other at two rates. Conventional lime plus topsoil, lime without topsoil, topsoil only, topsoil with fly ash, rock-P plus topsoil, and rock-P plus fly ash were also evaluated and compared with pure refuse controls. The columns were dosed weekly with 2.5 cm of simulated acid rain, an amount equivalent to 152 cm (60 in.) rainfall per year and remained unsaturated at all times. The experiment was conducted for 40 weeks. The drainage from the unamended columns rapidly dropped to less than pH 2 with very high levels of Fe, Mn, B, S, and Al. Alkaline fly ash dramatically reduced drainage Fe concentrations as well as Mn, Al, Cu and S when compared to the untreated refuse. As expected, lime treatments also reduced the drainage Fe, Mn, Al, Cu and S concentrations. The rock-P treatments initially reduced Fe, Mn, Al and S, but eventually decreased in mitigation capability over time. Leachate B concentrations were initially high for some of the ash columns but eventually followed the same B elution trend as the untreated refuse. The combined treatments of phosphate/ash, ash/topsoil, and pure refuse with topsoil were intermediate between the pure ash treatments and unamended refuse in drainage quality. The data were analyzed to determine treatment effectiveness in reducing AMD, and to evaluate the overall replicability of the column design. All treatments varied greatly for the first 5 weeks as the initial flush of salts from the materials occurred, but most treatments stabilized by week 6 with relatively low within treatment variability. The high ash blending rates remained alkaline for extended periods of time and stabilized pyrite while neutralizing any acidity. The rock-P treatment appears to have bound free Fe and other elements released from pyrite oxidation but did not prevent acidification. Long term analysis may prove fly ash to be a viable alternative to conventional topsoiling/lime treatments to ameliorate AMD if adequate alkalinity is present in the ash/refuse mixture. If fly ash alkalinity is inadequate to balance potential acidity, accelerated leaching of ash bound metals may occur. / M.S.

Over the course of our lives we are exposed to airborne particulate matter in the workplace, home, and environment that results in the deposition of millions of particles in the lung. These exposures may result in disease if they are significant enough. The potential for harmful exposure depends in part on the dust's biodurability and the bioavailability of harmful constituents derived from the particles. A mixed flow reactor was used to evaluate two applications of geochemical methods to characterize the behavior of inhaled particles in the body. Dissolution rates of a well-characterized sample of powdered talc were measured in solvents that mimic fluids found in the human lung. These studies showed that variation of solvent chemistry, including the addition of organic chelators and proteins at intercellular fluid concentrations, does not markedly affect the measured dissolution rate of talc at 37 degrees Celcius and the data further indicate that the dissolution mechanism for talc in aqueous solutions is independent of pH over a range of pH from 2 to 8. The dissolution rate, determined by measuring the silicon release rate per unit surface area of talc is 1.4 (+/- 1.0) x 10-11 mol Si/(m2 -sec). A geometric shrinking particle model using this dissolution rate predicts an estimated lifetime (upper limit) of approximately 8 years for a 1 micron talc particle under pulmonary conditions. Talc dissolves considerably faster than quartz, but slower than chrysotile and olivine in the body. These data can be used to place constraints on the role of particle dissolution in the disease models associated with airborne respirable particulate matter. Secondly, the bioavailability of As and Cr was determined from a sample of coal fly ash from an eastern U.S. power plant. The time-release profiles of As and Cr were determined for these materials in physiologically-based solvents and incorporated into a toxicokinetic model to predict the exposure potential to As and Cr from occupational exposures to the coal fly ash. Predicted occupational exposure contributions from the ash relative to total environmental exposures were insignificant. The exposure predicted from the geochemical approach was compared with results observed in a cohort occupationally exposed to coal fly ash and found to be within one order of magnitude of the response of the occupational cohort. These results support the application of geochemical techniques to evaluate exposures to complex respirable materials. / Ph. D.

Coal-fired power plants constitute a significant source of energy production for the United States, and are projected to do so for decades to come. Most of the scrutiny coal-fired power plants receive is in the form of environmental concerns regarding green house gas emissions of carbon dioxide, sulfur dioxide, and others. It is known that coal fly ash released through the stacks of coal power plants contains concentrated levels of naturally-occurring radiation, such as Radium-226. However, since the source of radiation is natural and the activity levels are low, there are no nuclear regulatory requirements imposed on coal plants. The focus of this study was to use the Nuclear Regulatory Commission’s (NRC) facility release criteria to determine whether the concentration of naturally occurring Radium-226 present in soil surrounding the Centralia Power Plant is elevated relative to soil collected 80 kilometers away. The non-parametric Wilcoxon Rank Sum test was used to compare twenty-eight soil samples collected within 3.4 kilometers of the Centralia Power Plant stacks against an equal number of reference samples collected in Port Orchard, Washington. It was determined that the average concentration of Radium-226 in soil near the power plant was 1.59 pCi/g, while the average concentration in reference soil was 0.59 pCi/g. The study suggests that the area around the power plant would fail to pass the release criteria of a NRC Multi-Agency Radiation Survey and Site Investigation (MARSSIM) Class 3 survey unit. If it is true that coal fired power plants increase background radiation levels measurably, but not at a level sufficient to cause alarm, it may be sensible to revise the strict emissions standards for nuclear facilities or increase requirements for utilities other than nuclear. / Graduation date: 2012

M. Tech. (Department of Chemical Engineering, Faculty of Engineering and Technology): Vaal University of Technology / Strict environmental regulation on flue gas emission has led to the implementation of FGD technologies in power stations. Wet FGD technology is commonly used because it has high SO2 removal efficiency, high sorbent utilization and due to availability of the sorbent (limestone) used. SO2 is removed by passing flue gas through the absorber where it reacts with the slurry containing calcium ions which is obtained by dissolution. This study presents the findings of the dissolution of a calcium-based material (limestone) for wet FGD process. This was done using a pH stat apparatus and adipic acid as acid titrant. Adipic acid was used because of its buffering effect in wet FGD process. The conditions used for this study are similar to what is encountered in a wet FGD process. The extent of dissolution was determined by analyzing the amount of calcium ions in solution at different dissolution periods. The dissolution kinetics were correlated to the shrinking core model and it was found out that chemical reaction at the surface of the particle is the rate controlling step. This study also investigated the dissolution of coal fly ash and bottom ash. Their dissolution kinetics showed that the diffusion through the product layer was the rate controlling step due to an ash layer formed around the particle. The formation of ash layer was attributed to pozzolanic reaction products which is calcium-alumino-silicate (anorthite) compounds were formed after dissolution. The effect of fly ash on the dissolution of rate of limestone was also studied using response surface methodology. Limestone reactivity was found to increase with increase in the amount of fly ash added and the pH was found to be strong function of the rate constant compared to other dissolution variables. The presence of silica and alumina in fly ash led to a significant increase in the specific surface area due to hydration products formed after dissolution. / Eskom

Les Cendres Volantes d’Electrofiltres (CVE) d’incinération d’ordures ménagères sont considérées comme des déchets dangereux et mises en décharges après une phase de stabilisation et de solidification par un liant hydraulique. Leur utilisation dans des matériaux cimentaires permet l’élimination d’un déchet en diminuant la demande de matériaux de construction. Cependant, avant leur incorporation dans des matériaux cimentaires, les CVE doivent subir plusieurs traitements. Premièrement, un lavage à l’eau permet de diminuer fortement la concentration en chlorures. Dans un deuxième temps, une séparation granulométrique des CVE est appliquée afin de ne sélectionner que la fraction la moins contaminée en métaux lourds, notamment en plomb et en zinc, ces métaux lourds étant connus comme retardateurs de prise. Enfin, une troisième étape consiste à oxyder l’aluminium métallique présent dans les CVE à l’aide d’un lavage basique à l’hydroxyde de sodium. S’il n’est pas oxydé durant la phase de traitement, l’aluminium métallique se transforme en aluminates dans la matrice cimentaire tout en produisant de l’hydrogène, responsable de l’apparition de vides et de fissures endommageant ainsi le matériau. Une fois traitées, les CVE peuvent alors être utilisées en substitution partielle du ciment pour une étude de leur réactivité potentielle. Les résultats de cette étude ont montré que l’activité des CVE traitées à l’hydroxyde de sodium est principalement d’origine physique (granulométrique et surface développée). Les CVE ne présentent pas de nature pouzzolanique. Les essais de lixiviation ont montré une durabilité équivalente et une très bonne stabilisation du chrome, du plomb et du zinc, qui permet de respecter les normes environnementales européennes./Municipal Solid Waste Incineration (MSWI) Electrofilter Fly Ash (EFA) is considered as hazardous waste and landfilled after stabilisation and solidification with a hydraulic binder. Its use in cementitious materials allows the elimination of a waste and a decrease of construction materials use. However, before its incorporation in cementitious materials, EFA has to be treated. Firstly, a water washing allows an important decrease in chloride concentration. In a second time, size-based separation is used to select the less heavy metals contaminated fraction, especially in lead and zinc. Indeed, these heavy metals are knows as setting retarders. Finally, a third step involves oxidizing of metallic aluminium contained in EFA during a basic washing with sodium hydroxide. Indeed, if it is not oxidize during the treatment, metallic aluminium converts in aluminates in the cementitious material, and produces hydrogen, generating cracking and voids, and damaging the cementitious material. After the treatment step, a study of the potential reactivity of EFA used in partial replacement of cement is carried out. Results show the activity of EFA treated with sodium hydroxide is mainly physical (grading and developed surface). EFA presents not pozzolanic effect. Leachability tests show an equivalent durability and a very efficient stabilisation of chrome, lead and zinc, allowing the respect of the European environmental standard. / Doctorat en Sciences de l'ingénieur / info:eu-repo/semantics/nonPublished

Chan Chik-yu. / Thesis submitted in: December 1998. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (leaves 128-152). / Abstract also in Chinese. / Acknowledgments --- p.i / Abstract --- p.ii / Table of Contents --- p.vi / List of Tables --- p.ix / List of Figures --- p.xi / List of Plates --- p.xiii / Chapter Chapter 1 --- INTRODUCTION --- p.1 / Chapter 1.1 --- Fly Ash --- p.1 / Chapter 1.1.1 --- Formation of fly ash --- p.1 / Chapter 1.1.2 --- Physical and chemical properties of fly ash --- p.1 / Chapter 1.1.3 --- Disposal --- p.3 / Chapter 1.2 --- Problems Associated with the Reclamation of Fly Ash --- p.5 / Chapter 1.2.1 --- Physical problems --- p.6 / Chapter 1.2.2 --- Nutrient problems --- p.6 / Chapter 1.2.3 --- Toxicity problems --- p.6 / Chapter 1.2.4 --- Biological problems --- p.7 / Chapter 1.3 --- Ecological Considerations on Wasteland Reclamation --- p.7 / Chapter 1.3.1 --- Ecological basis --- p.7 / Chapter 1.3.2 --- Problems of ecosystem development and its treatments --- p.11 / Chapter 1.4 --- Obj ectives of the Present Study --- p.17 / Chapter Chapter 2 --- EDAPHOLOGICAL CHARACTERISTICS OF FLY ash and vegetation composition on fly ASH LAGOON --- p.23 / Chapter 2.1 --- Introduction --- p.23 / Chapter 2.2 --- Materials and Methods --- p.24 / Chapter 2.2.1 --- Site description --- p.24 / Chapter 2.2.2 --- Collection of fly ash and soil samples --- p.25 / Chapter 2.2.3 --- Physical analysis --- p.26 / Chapter 2.2.4 --- Chemical analysis --- p.26 / Chapter 2.2.5 --- Vegetation analysis --- p.27 / Chapter 2.2.6 --- Statistical analysis --- p.27 / Chapter 2.3 --- Results and Discussion --- p.28 / Chapter 2.3.1 --- Physical properties --- p.28 / Chapter 2.3.2 --- Chemical properties --- p.33 / Chapter 2.3.3 --- Vertical ash profile --- p.42 / Chapter 2.3.4 --- Vegetation survey --- p.48 / Chapter 2.4 --- Conclusions --- p.58 / Chapter Chapter 3 --- GREENHOUSE PLANT SELECTION AND AMELIORATION TRIALS ON LAGOONED FLY ASH --- p.60 / Chapter 3.1 --- Introduction --- p.60 / Chapter 3.2 --- Materials and Methods --- p.62 / Chapter 3.2.1 --- Collection of lagooned fly ash and planting materials --- p.62 / Chapter 3.2.2 --- Plant selection trial --- p.63 / Chapter 3.2.3 --- Amelioration trials --- p.66 / Chapter 3.2.4 --- Statistical analysis --- p.68 / Chapter 3.3 --- Results and Discussion --- p.68 / Chapter 3.3.1 --- Plant selection trial --- p.68 / Chapter 3.3.2 --- Amelioration trials --- p.75 / Chapter 3.4 --- Conclusions --- p.83 / Chapter Chapter 4 --- LEACHING OF SOLUBLE SALTS AND BORON FROM LAGOONED FLY ASH --- p.84 / Chapter 4.1 --- Introduction / Chapter 4.2 --- Materials and Methods --- p.86 / Chapter 4.2.1 --- Setup of column --- p.86 / Chapter 4.2.2 --- Leaching regimes --- p.86 / Chapter 4.2.3 --- Growth of ryegrass on leached ashes --- p.89 / Chapter 4.2.4 --- Chemical analysis on ashes --- p.89 / Chapter 4.2.5 --- Statistical analysis --- p.89 / Chapter 4.3 --- Results and Discussion --- p.90 / Chapter 4.3.1 --- Leaching of soluble salts and B --- p.90 / Chapter 4.3.2 --- Plant growth in leached ashes --- p.101 / Chapter 4.4 --- Conclusions --- p.105 / Chapter Chapter 5 --- EFFECTS OF ORGANIC AMENDMENTS ON plant growth on pre-leached fly ash --- p.106 / Chapter 5.1 --- Introduction --- p.106 / Chapter 5.2 --- Materials and Methods --- p.108 / Chapter 5.2.1 --- Collection of materials --- p.108 / Chapter 5.2.2 --- Chemical analysis of planting media --- p.108 / Chapter 5.2.3 --- Plant growth experiment --- p.109 / Chapter 5.2.4 --- Statistical analysis --- p.110 / Chapter 5.3 --- Results and Discussion --- p.110 / Chapter 5.3.1 --- Chemical properties --- p.110 / Chapter 5.3.2 --- Plant growth on organic-amended ash --- p.116 / Chapter 5.3.3 --- Plant elemental uptake --- p.118 / Chapter 5.4 --- Conclusions --- p.123 / Chapter Chapter 6 --- GENERAL CONCLUSIONS --- p.125 / References --- p.128

About one third of all edible food is wasted globally each year. This calls for improvements in resource and waste management. An interesting solution for organic waste is fly larvae composting, which both produces protein in the form of larvae and a nutrient rich residue. The larvae can be used as animal feed while the residue can be applied as an organic fertilizer, thus recycling the nutrients. Fly larvae composting with the black soldier fly (BSF), Hermetia illucens, is relatively new, but there is extensive research on how the treatment is affected by different parameters, e.g. temperature, moisture and type of organic waste that is treated. The role of bacteria has only been the topic of a few studies in recent years but has shown promising positive effects on larval growth. This study investigated the impact of bacteria isolated from BSF eggs on fly larvae composting of food waste by BSF larvae. The study was done in two experimental phases. In phase I, groups of three bacteria were added to each treatment together with the larvae and only single treatments were executed; in phase II triplicates of promising groups of three, two or single bacteria were evaluated. The results of phase I suggested that selected groupings of bacteria could either decrease or increase the bioconversion ratio and in general decrease the reduction ratio of the food waste, while the survival ratio did not seem to be impacted. However, in phase II no significant difference (p<0.05) between the treatments with bacteria and the control were found for any evaluated variables. Interestingly, the variation in resulting bioconversion ratio and reduction ratio (on a VS basis) was found to be reduced when one or more bacteria were present. The coefficient of variation in bioconversion ratio was 9.5% for the control compared to between 2.5% and 6.1% for treatments with bacteria. For the reduction ratio the variation was reduced from 5.6% and to between 0.9% and 4.6% for the bacteria treatments. Hence, seeding with bacteria may improve stability of the process, which is especially interesting when scaling up the process. / Globalt slängs ungefär en tredjedel av all ätbar mat. Därmed finns ett stort behov av säker och hållbar avfallshantering. En intressant lösning för organiskt avfall är fluglarvskompostering, som både producerar protein i form av larver och en näringsrik behandlingsrest. Larverna kan exempelvis användas som djurfoder medan behandlings-resten kan användas som gödselmedel, vilket innebär att näring kan återvinnas. Fluglarvskompostering med amerikansk vapenfluga (BSF), Hermetia illucens, är en relativt ny teknik men det finns redan omfattande forskning på hur olika processparametrar, t.ex. temperatur och vattenhalt, påverkar processen. Bakteriers roll har studerats endast i ett fåtal studier men de indikerar att tillsats av bakterier kan ha en positiv inverkan på larvernas tillväxt. Den här studien har därför undersökt hur tillsats av bakterier isolerade från BSF ägg påverkar fluglarvskompostering av matavfall med BSF larver. Studien gjordes i två experimentella delar. I fas I undersöktes effekten av tillsats av bakteriegrupper om tre bakterier till matavfallet samtidigt med larverna; i fas II utfördes triplikat av lovande bakteriegrupper med tre, två eller enstaka bakterier. Resultaten från fas I indikerade att olika bakteriegrupper antingen kunde höja eller sänka bioomvandlingskvoten och generellt gav en minskning i materialreduktions-kvoten medan överlevnadsgraden inte verkade påverkas i samma utsträckning. I fas II observerades däremot ingen signifikant skillnad (p<0,05) mellan någon av bakteriebehandlingarna och kontrollen för samtliga processvariabler. Variationen i resulterande bioomvandlingskvot och materialreduktionskvot (på VS basis) var dock lägre för bakteriebehandlingarna jämfört med kontrollen. Variationen i bioomvandlings-kvot var 9,5% för kontrollen jämfört med 2,5-6,1% för bakteriebehandlingarna. För materialreduktionskvoten minskade variationen från 5,6% till mellan 0,9% och 4,6%. Detta tyder på att tillsats av bakterier kan förbättra stabiliteten hos fluglarvskompostering, vilket är särskilt intressant vid uppskalning av processen.