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- Haller, Henrik, 1977-
(författare)
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Appropriate Technologies for Soil Remediation in Low Prioritized Region : Developing Countries and Sparsely Populated Regions
- 2015
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Contaminated sites in low prioritized regions demand remediation technologies that are cost- and energy-effective and locally adapted. Parameters such as the time frame during which bioremediation degradation needs to occur may not be as restraining as in urban environments. This licentiate project aims to explore opportunities and constraints for appropriate soil remediation based on organic by-products in tropical developing countries and sparsely populated areas in industrial countries. Ecological Engineering and the Framework for Strategic Sustainable Development were explored as planning tools to steer bioremediation methods towards sustainability. The use of the five concepts of Ecological Engineering within the Framework for Strategic Sustainable Development can steer bioremediation in low prioritized regions towards sustainability. Pilot-scale and laboratory experiments were undertaken to evaluate the feasibility of such bioremediation methods. Experiments carried out at the experiment station in Chontales, Nicaragua showed some promising results, but also revealed problems associated with the clay rich soils, which are typical for tropical regions. Treatment of diesel contaminated ultisol with 6 mL whey kg-1 dw in a pilot-scale experiment considerably increased the degradation rate of diesel constituents, but no effects on the degradation rates were observed after treatment with compost tea or pyroligneous acid.The soil columns study suggests that despite a favorable particle size distribution for microbial transport, the sandy loam retained a greater fraction of the microorganisms present in the ACT in the top 10 cm than the clay loam, presumably because the lower bulk density and higher SOM in the clay loam aided transport and growth of microorganisms.
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| 2. |
- Cuadra, Steven
(författare)
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Child labour and health hazards: chemical exposure and occupational injuries in Nicaraguan children working in a waste disposal site
- 2005
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- About 600 children and teenagers work at Managua's landfill, the largest in Nicaragua. They collect and sort waste at the open dump, which covers an area of 7 km2 on the outskirts of the city on the shores of Lake Managua. Such work, which occurs in many large cities in developing countries, is considered to be one of the riskiest types of child labor that exists. Nevertheless, knowledge of such work and its risks is lacking.We investigated chemical exposure and risk of injury among 103 child laborers aged 6 to 15 years from Managua's landfill. Almost half of the children also lived in the dump area itself, while the rest lived in a nearby area, Acahualinca. For comparison, 102 children from Acahualinca and 34 children from central Managua, 10 km away, who did not work at the dump, were also studied. This provided the opportunity to also study the environmental exposure from the landfill. The children were interviewed about living conditions, working conditions, and all injuries that occurred at workplaces, at school, and at home during the last 12 months. They had to provide blood samples for examination of the levels of, among other things, heavy metals such as lead, mercury, and cadmium, and persistent organic environmental toxins such as pesticides and PCBs. We also investigated the levels of a relatively new organic environmental poison, the brominated flame retardant PBDE. At a later stage, soil samples were also collected from the landfill area and from Acahualinca for investigation of metal content.The children who worked at the landfill had higher levels of lead, mercury, and cadmium than the children in the comparison groups. One-third had blood lead levels higher than 100 μg/l, a level where measures to reduce exposure are clearly recommended. We also found that the children in the nearby residential area had higher lead levels than the children from central Managua. Although mercury levels were higher among the child workers, the levels were not such that they could be considered a present and clear health risk. Consumption of fish from Lake Managua only slightly affected mercury levels. The levels of several of the organic environmental toxins, especially PCBs, were also higher among the child workers than in the comparison groups. We know that PCBs, which have long been banned in the West, are still used in Central America, or stored in uncontrolled forms. The children in the comparison groups also had clearly higher levels of a breakdown product of the pesticide DDT and of PCBs than children in the USA and Western Europe. The levels of these substances are steadily decreasing in the Western world. There is extremely limited knowledge of how the development over time looks like in Central and Latin America because too few surveys have been carried out. Unexpectedly, we found extremely high levels of PBDEs among the children living and working at the dump, higher than previously reported. The children in the comparison groups also had unexpectedly high levels of these substances. This is the first investigation of human PBDE levels in Central and Latin America, and the findings clearly show that it is extremely important to study the spread of the new environmental toxins also in non-industrialized countries and among particularly vulnerable groups. Several of the different substances that we studied are toxic to reproduction, and they can negatively affect human reproduction and fetal development. It would therefore have been desirable to be able to make a balanced risk assessment, but this is not possible because there is a lack of knowledge about the synergistic effects of the substances, and especially about how other factors such as inadequate nutrition can further affect the risk picture. What is clear, however, is that the levels we found among the children are significant from a reproductive perspective, as many of the girls we surveyed will be mothers in a few years - a fifth of Managua's teenagers are pregnant or have given birth already.Injuries, which caused at least one day of absence from school or work, were seven times more common among the children working at the dump than among the children in the comparison groups. The vast majority of injuries occurred during work, corresponding to 2.2 injuries per 1000 working days. The children reported that approximately one in ten injuries had resulted in permanent disability or pain. We analyzed the injuries that occurred to clarify whether there were any clear injury patterns. Cuts and puncture wounds to the hands and feet in connection with material handling were most common and caused 70% of the injuries. This shows that simple protective measures – many children lack shoes and no one has gloves – could reduce the risk of injury. However, the most serious damage was caused by the vehicles at the dump.In our studies, we have wanted to measure exposure levels and quantify risks in order to clarify the situation of child workers, in the hope that increased knowledge and awareness can eventually contribute to change. We have also gained valuable knowledge about the levels of several common environmental toxins among ordinary poor city children in a developing country. This is something that has so far been too inadequately investigated.
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| 3. |
- Vargas Chevez, Norman, 1976-
(författare)
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A unified strategic business and IT alignment model : A study in the public universities of Nicaragua
- 2010
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A number of attempts have been made to define strategic business and information technology (IT) alignment; several representations of what it is are available in academic and practitioners’ fields. The literature suggests that firms need to achieve strategic business and IT alignment to be competitive. Strategic business and IT alignment impact business performance and IT effectiveness. We propose a unified strategic business and IT alignment model based on four strategic business and IT alignment models: Strategic Alignment Model (SAM), Strategic Alignment Maturity Model (SAMM), information system strategic alignment model and an operational model of strategic alignment. I argue that such a unified model will provide a better understanding of the nature and key aspects of strategic business and IT alignment from different, and sometimes complementary, theories. The unified model represents the concepts and instruments used in these four strategic businesses and IT alignment models. Our principal research goal is to pave the way to develop a common understanding between the different models. The components of the unified strategic business and IT alignment model were ranked with a group of IT experts and business experts from four public universities in Nicaragua. The result can be used as a basis for improving strategic business and IT alignment.
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| 4. |
- García, Indiana, 1966-
(författare)
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Removal of natural organic matter by enhanced coagulation in Nicaragua
- 2005
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The existence of trihalomethanes (THMs) in a drinking water plant of Nicaragua has been investigated in order to see whether the concentration exceeded the maximum contaminant level recommended by the environmental protection agency of the United States (USEPA) and the Nicaragua guidelines. The influence of pH, temperature, chlorine dose and contact time on the formation of THMs were studied. The contents of organic matter measured by surrogate parameters such as total organic carbon, dissolved organic carbon, ultraviolet absorbance and specific ultraviolet absorbance were also determined in order to show which type of organic matter is most reactive with chlorine to form THMs. Models developed by other researchers to predict the formation of trihalomethanes were tested to see whether they can be used to estimate the trihalomethane concentration. In addition, empirical models were development to predict the THM concentration of the drinking water plant analysed. The raw water was treated by conventional and enhanced coagulation and these processes were compared with regard to the removal of natural organic matter (NOM). The significance of the results was assessed using statistic procedures. The average concentration of THMs found at the facility is below the USEPA and Nicaragua guideline values. Nevertheless the maximum contaminant level set by USEPA is sometimes exceeded in the rainy season when the raw water is rich in humic substances. Comparison between the water treated by conventional and enhanced coagulation shows that enhanced coagulation considerably diminished the trihalomethane formation and the value after enhanced coagulation never exceeded the guidelines. This is because enhanced coagulation considerably decreases the organic matter due to the high coagulant dose applied. The study of the trihalomethane formation when varying pH, time, temperature and chlorine dose using water treated by conventional and enhanced coagulation showed that higher doses of chlorine, higher pH, higher temperature and a longer time increases the formation of THMs. However, combinations of two and three factors are the opposite. The predicted THM formation equations cannot be used for the water at this facility, since the results shown that the measured THM differs significantly from the THM concentration predicted. Two empirical models were developed from the data for enhanced coagulation, using linear and non-linear regression. These models were tested using the database obtained with conventional coagulation. The non-linear model was shown to be able to predict the formation of THMs in the Boaco drinking water plant.
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| 9. |
- Conde Jacobo, Alexander Vladimir, 1979
(författare)
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Application of DOAS for Studies of Evolving Volcanic Activity in Central America
- 2012
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Volcanic gas emissions play a critical role in understanding the physical processes that drive eruptive activity. Combining gas measurements with other geophysical parameters provides a more accurate description of the changes that occur beneath a volcano. Understanding and tracking the evolution of volcanic activity is crucial for populated areas that may be affected by a potential eruptive crisis.This thesis illustrates the application of ground-based optical remote sensing using Differential Optical Absorption Spectroscopy (DOAS) for measuring volcanic gas emissions. Some measurements have been made within a range of several days to a few weeks, while in some cases we made measurements for more than one year. The case studies include the following volcanoes: Turrialba (Costa Rica), Concepción (Nicaragua), Arenal (Costa Rica), and Télica (Nicaragua).At Turrialba volcano the measured SO2 flux emissions clearly indicated an imminent eruptive event. The volcano’s degassing evolution during different periods was extensively compared with the most relevant seismic signatures. At Concepción volcano our measurements were related to seismic and geodesic indicators during an active eruptive period and a quiescent period. Preliminary results of ongoing measurements at Télica and Arenal volcano are also reported.Different comparisons in different scenarios provide multi-parametric surveillance methods that may be adopted by local institutions in charge of dealing with volcanic risk assessment.
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| 10. |
- Korsak, Larisa
(författare)
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Anaerobic treatment of wastewater in a UASB reactor
- 2008
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The anaerobic treatment of waste water has been studied with an emphasis on the Up- flow Anaerobic Sludge Blanket (UASB) reactor. A model to describe the processes occurring in a UASB reactor was developed and an experimental study of the anaerobic wastewater treatment systems in Nicaragua was also performed. Experimental work was carried out in order to link the study to the wastewater treatment situation in Nicaragua, a developing country. In order to assess the performance of the treatment plants, the methanogenic activity of sludge from seven anaerobic wastewater treatment plants was first addressed. Due to a lack of Standards for the measurement of methanogenic activity, a laboratory method was developed based on the methods found in the literature. An additional aim of this study was to find adequate inoculum for the wastewater treatment plant in a brewery using an anaerobic reactor. Physic-chemical characteristics of the sludge were also determined to provide a basis for decisions regarding the agricultural employment of the sludge from the treatment plants. A one-dimensional model describing the physical and biological processes occurring in an Up-flow Anaerobic Sludge Blanket reactor has been developed. These processes are advection, dispersion and reaction in the granule, including mass transport at the interface and diffusion within the particle. The advection-dispersion equation is used to describe these phenomena in the reactor. Dispersion is mainly caused by the gas bubbles rising up through the reactor and the granules in the ascending flow. The extent of the dispersion is expressed by the dimensionless Peclet (Pe) number. It is assumed that the biological degradation takes place at the surface and within the granules. The processes occurring in the granules formed by the microorganisms are described in detail; they include diffusion in the stagnant film around the granule, diffusion within the particle, and a degradation reaction. From these processes, the reaction term is analytically determined. The granules were modelled as spherical porous biocatalysts of different sizes. The biochemical degradation reactions were assumed to follow Monod type kinetics of the first order. For the numerical solution of the model, a standard program was used (Within MATLAB). The model was applied to some experimental data taken from the literature. An important characteristic of the model is that it can simultaneously take into account reactions in granules of different sizes. At present, the parameters of the model are calculated using data from the literature; but experimental measurements of the main parameters are planned. The impact of the different parameters was studied by numerical simulation and its validity was tested using experimental data reported in the literature. The model could be a useful tool in the performance optimization of UASB reactors by predicting the influences of different operational parameters.
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