Dissertations / Theses on the topic 'Conversion process'

Canadian Electrolytic Zinc in Valleyfield, Quebec utilizes the conventional Roast-Leach-Electrowin process to produce zinc metal. Iron removal is carried out in the jarosite conversion circuit which consists of ten continuous stirred tank reactors in series.
In this study, the first five tanks of the jarosite conversion circuit were piloted and process identification experiments were carried out. Step changes in the flows of the raw acid, spent acid, jarosite slurry and zinc ferrite slurry streams were performed. The goal of these experiments was to collect transient response data which could be used to validate a dynamic conversion circuit model. The process was found to be most sensitive to changes in the flow of the raw acid stream.
The zinc ferrite dissolution rate constant calculated from the experimental data agrees with literature values. Using a jarosite precipitation rate expression from the literature, it was found that jarosite precipitation is negligible in the first reactor but cannot be ignored in the second tank.
The dynamic model provides a good representation of the first two tanks of the jarosite conversion circuit and can be used for both process control and optimization studies on a full-scale facility.

I rapporten framgår det en termodynamisk analys för reverse water gas shift med att sammanmata etanol för att undvika det långsammaste steget i reaktionen för att producera högre alkoholer. Ifrån ett termodynamiskt perspektiv, verkar det möjligt att utgå ifrån reverse water gas shift för att producera högre alkoholer vid 100 bar med en temperatur på 300C . Reaktionen är exotermisk, vilket gynnas av det låga temperaturer och det rekommenderas höga tryck p.g.a. en mol kontraktion. Jämviktshalterna var låga, det föreslås att ta bort vatten ifrån jämvikten.  I den matematiska modellen utgick det ifrån en kedja-reaktion för att producera högre alkoholer med reverse water gas shift i processförhållanden på 10–200 bar. I modellen utfördes en senstivty-analysis för jämvikten på tryck och vattenborttagning. Genom att ta bort vatten ifrån jämvikten låg CO2 utbytet kring 95% vid 200 bar även vid låga tryck som 10 bar. Inom CO2 hydrering till högre alkoholer är det begränsat med data och reaktionsmekanismen bakom reaktionen är inte riktigt förstådd. Experimentella försök krävs för att få en mer ökad förståelse. I modellen beskrevs CO2 hydrering och resterande reaktioner som en funktion av en sigmoid. Inom litteraturstudien kom det fram till att det fanns ingen kommersiell tillgänglig membran förtillfället för att ta bort vatten inom krävande process förhållanden. Tekniken ser dock lovande ut.
In this work, a thermodynamic analysis for CO2 hydrogenation by co-feeding ethanol to higher alcohols was performed with the HSC software package. The results suggested a high pressure and a low temperature for the reaction. However, it yielded low equilibrium compositions for the higher alcohols even at a high pressure of 100 bar at 300C . Increasing the equilibrium compositions for the higher alcohols can be done by removing water.  A mathematical model was used to analyse the rate-limiting step in a process for the production of higher alcohols from CO2.  In this process, reverse water gas shift (RWGS) reaction was used to convert CO2 to CO, subsequently, the obtained CO reacts with ethanol and hydrogen to produce higher alcohols directly. The mathematical model was developed in MATLAB to simulate how the reaction could behave by feeding CO2, H2 and ethanol at different pressures ranging from 10-200 bars. The water removal effect on the equilibrium is measured in terms of CO2   conversion by achieving 95% for removing water.  The results indicated that the process can be used to convert CO2 to higher alcohols and at a lower pressure. The limiting factor for CO2 hydrogenation is the reaction mechanism, it’s an urgent problem for the development of the catalysts. In this model it was assumed to be a logistic function. The conversion of CO2 into higher alcohols is an important problem that is required to be addressed by more experimental verifications to understand the mechanism. The literature review shows that there is no available membrane for removal of water for the process currently, due to the harsh process conditions, mainly because of the membrane stability. However, membrane technology is a promising method for separation of water/organic mixtures that can be studied further in the future.

Thesis (Ph.D.) -- University of Maryland, College Park, 2009.
Thesis research directed by: School of Public Policy. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

Proper attachment of chromosomes to microtubules is important for the accurate segregation of chromosomes and genome stability. The initial engagement of chromosomes happens along the lateral wall of microtubules through a highly specialised protein structure assembled on the centromeric DNA, the kinetochore. Ultimately, kinetochores must be attached to the ends of microtubules (a geometry called end- on attachment). A series of highly dynamic steps called the end-on conversion process, converts the initial immature lateral attachments into mature end-on attachments. How this process is finely tuned by phosphorylation and dephosphorylation to achieve stable attachments is still unclear. Furthermore, what is the role of microtubule-associated proteins in the stabilisation of kinetochore-microtubule attachments is unknown. This project aimed to study the role of phosphatases in the regulation of the end-on conversion process. First, I investigated the different contribution of the two outer-kinetochore phosphatases - BubR1- recruited PP2A-B56 and KNL1-recruited PP1 - in counteracting Aurora B kinase during the end-on conversion process. I found that BubR1-recruited PP2A-B56 plays an essential role in the process, but KNL1-recruited PP1 does not. I also investigated whether the HEC1/Ndc80 N-tail is a critical substrate of Aurora B phosphorylation for the stabilisation of the end-on attachments. Using a phospho-dead mutant of the HEC1/Ndc80 N-tail, I discovered that cells are still susceptible to Aurora B activity, indicating downstream pathways independent of HEC1/Ndc80. Then, I studied the biological role of the Astrin C-terminus, where an evolutionarily conserved RVMF motif, a putative PP1 binding site, is located. My findings show C-terminal Astrin mutants fail to localise at kinetochores of both monopolar and bipolar spindles; induce defects in the end-on conversion process in monopolar spindles and prolong mitosis time with increased Mad2 levels at the outer-kinetochore. A kinase inhibitor assay showed that kinetochore-microtubule attachment defects in Astrin mutant expressing cells could be rescued when both Aurora B and Cdk1 kinases are inhibited, suggesting a role for Astrin’s C-terminus in counteracting Aurora B and Cdk1 activity. Finally, I probed the putative interaction of the Astrin C-terminus and PP1 using biochemistry, cell biology and fluorescence microscopy techniques. I discovered that artificially targeting PP1 onto the Astrin C-terminus but not on the N-terminus rescues mutants localisation defects at the kinetochore. In summary, my results indicate that Astrin and PP1 interact at the kinetochore of living cells. In conclusion, my work shows that mitotic phosphatases have distinctive contributions in the regulation of the dynamic steps of the end-on conversion process and that Astrin is a potential PP1 phosphatase recruiter at the outer-kinetochore, where is necessary for the stabilisation of end-on attachments.

Re-use is the fundamental means of sustaining and thus conserving modest architectural heritage (Grade II listed buildings). Currently, it remains a marginal activity within property development as the direct agents perceive the re-use process to be more complex, construction and project costs to be higher, and the project duration to be longer than new built projects. As a result, the risk of vacancy and obsolescence in architectural heritage Increases. The author asserts that understanding the actual dynamics of the process, and identifying the factors that increase the chances of overcoming challenges associated with re-use, and thus achieving a successful outcome, would be Instrumental In firstly evaluating the validity of the above perceptions, which are widely published in the related literature, and then proposing a 'good practice re-use process' that can be adopted to similar projects. Hence, agents would become equipped with the know-how of carrying out re-use projects. Eventually, re-use would move towards the centre of the property development domain, and subsequently our capacity for sustaining architectural heritage would have increased. Therefore, this thesis focuses on the process of re-using listed buidings. It adopts a process mapping approach m a case study context. The development processes of three re-use projects in London are mapped. The process mapping approach adopted is novel to the property development sector. Its novelty lies in two areas. Firstly, it maps the actual processes instead of proposing a normative process protocol. Secondly, it devises a methodological approach, which is both flexible enough to allow data to 'speak for itself', and systematic enough to allow for rigorous and consistent analysis of rich and extensive qualitative data. Comparative analysis of the maps follow process mapping. Here, the aim is to assess process performances and project outcomes. Then a 'good practice guide for re-use process' is proposed. This is based on the findings of the comparative analysis. The research has shown that the re-use process is complex, but is still possible to achieve success if the development team is competent in managing complexity, flexible and responsive, and adopts a holistic project perspective. Even if the development teams do not have these attributes, they can successfully complete a re-use project if the market is buoyant. The buoyancy of the market can thus counter-balance the direct agents' reluctance to get involved and increase the opportunities of re-using listed buildings. The challenge is to establish and sustain the attributes the development team needs to possess to achieve success in the development/construction industry where short-termism still overrides. Until this is achieved, re- - use is likely to continue to be a marginal activity dominated by a small number of development teams with expertise in the field at locations and times of market depression.

The replacement of fossil resources through renewable alternatives is one way to mitigate global climate change. Biomass is the only renewable source of carbon available for replacing oil as a refining feedstock. Therefore, it needs to be utilized not just as a fuel but for both biochemical and thermochemical conversion through biorefining. Optimizing and combining various conversion processes using a system perspective to maximize the valorization, biomass usage, and environmental benefits is of importance. This thesis work has evaluated the integration opportunities for various thermochemical conversion processes within a biorefinery system. The aim for all evaluated concepts were syngas production through gasification or reforming. Two potential residue streams from an existing biorefinery were evaluated as gasification feedstocks, thereby combining biochemical and thermochemical conversion. Torrefaction as a biomass pretreatment for gasification end-use was evaluated based on improved feedstock characteristics, process benefits, and integration aspects. A system concept, “Bio2Fuels”, was suggested and evaluated for low-temperature slow pyrolysis as a way to achieve simultaneous biomass refinement and transport driven CO2 negativity. Syngas was identified as a very suitable intermediate product for residue streams from biochemical conversion. Resulting syngas composition and quality showed hydrolysis residue as suitable gasification feedstock, providing some adjustments in the feedstock preparation. Gasification combined with torrefaction pretreatment demonstrated reduced syngas tar content. The co-gasification of biogas and wood in a FBG was successfully demonstrated with increased syngas H2/CO ratio compared to wood gasification, however high temperatures (≥1000°C) were required for efficient CH4 conversion. The demonstrated improved feedstock characteristics for torrefied biomass may facilitate gasification of biomass residue feedstocks in a biorefinery. Also, integration of a torrefaction unit on-site at the biorefinery or off-site with other industries could make use of excess low-value heat for the drying step with improved overall thermal efficiency. The Bio2Fuels concept provides a new application for slow pyrolysis. The experimental evaluation demonstrated significant hydrogen and carbon separation, and no significant volatilization of ash-forming elements (S and Cl excluded)  in low-temperature (<400°C) pyrolysis. The initial reforming test showed high syngas CH4 content, indicating the need for catalytic reforming. The collective results from the present work indicate that the application of thermochemical conversion processes into a biorefinery system, making use of by-products from biochemical conversion and biomass residues as feedstocks, has significant potential for energy integration, increased product output, and climate change mitigation.

Greenhouse gas emissions caused by iron and steel industry are an important part of the world’s total greenhouse gas emissions. This bachelor’s thesis aims to compare different biofuels, which could replace the fossil fuels use in the process. The comparison takes place mainly in production costs and production technologies angles. The data used in this work is collected together from articles about bioenergy and biofuels, that are published in year 2005 or after. When comparing the biofuels, their feedstock, production capacity, production technology, location, base year and production costs are taken into account. Each biofuel is also analysed in more detail in their own chapters. Finally, the data is tabulated for easier comparison. To ease the comparison, the production costs of different biofuels are collected and unified into a single table. It can be stated from the results, that as a general rule, the surveyed biofuels are uneconomical compared to the fossil fuels used in the iron and steel industry. However, as bio reductants are receiving constantly more attention, new production methods as well as new possibilities for their future exploitation in industry can be assumed, while replacing fossil fuels and reducing greenhouse gas emissions
Rauta- ja terästuotannon aiheuttamat kasvihuonepäästöt ovat merkittävä osa maailman kokonaiskasvihuonepäästöistä. Kandidaatintyön tavoitteena on vertailla eri biopolttoaineita, joilla olisi mahdollista korvata prosessissa käytettäviä fossiilisia polttoaineita. Vertailu tapahtuu pääosin tuotantokustannuksien ja -teknologioiden näkökulmista. Työssä käytetyt tiedot on koottu vuonna 2005 ja sen jälkeen julkaistuista bioenergiaa ja -polttoaineita koskevista artikkeleista. Biopolttoaineita vertaillessa on otettu huomioon niiden valmistuksessa käytettävät raaka-aineet, tuotantokapasiteetti, tuotantoteknologia, sijainti, perusvuosi ja tuotantokustannukset. Jokainen työssä käsitelty biopolttoaine on myös analysoitu tarkemmin omassa luvussaan. Tiedot ovat lopuksi taulukoitu helpompaa vertailua varten. Vaihtoehtojen valmistuskustannuksia on myös pyritty yhtenäistämään taulukossa. Tuloksista voidaan todeta tarkasteltavien biopolttoaineiden olevan pääsääntöisesti taloudellisesti kannattamattomia verrattuna rauta- ja terästeollisuudessa käytössä oleviin fossiilisiin polttoaineisiin. Biopelkistimien saaman kasvavan huomion voidaan kuitenkin olettaa tuovan uusia valmistusmenetelmiä sekä mahdollisuuksia niiden hyödyntämiselle tulevaisuuden teollisuudessa korvaten fossiilisten polttoaineiden käyttöä, samalla kasvihuonepäästöjä pienentäen

Abstract This thesis discusses the development of a simulation model using artificial neural networks to model and predict the outcome of commercial process at a Shiprepair Conversion yard. Based on the data collected from across the A&P group a simulation model of the commercial process was developed. It was considered that contrary to the popular belief of securing one in five enquires as a potential contract the model can predict the probability of the outcome of a contract. The aim of the simulation is to ultimately develop a decision making tool for the ship repair industry which could help predict the outcome of the an enquiry based on certain parameters, hence reducing the estimating time and giving yards an advantage over their competitors. The research work looks into the estimation and management of Shiprepair and conversion processes, identifies the key stakeholders in the process and looks at the inherent risks of outdated technologies. The development of an intelligent supply chain management will enhance the yards product ability, help reduce the over heads and decrease the tendering process for the total repair. The challenges of assembling and deploying integrated supply chain are not unique to the Shiprepair industry. Increasing international pressures are motivating all industrial corporations continuously to reduce cycle times, manufacturing & administrative costs and to increase productivity. In addition, to improve internal production efficiency shipyards are turning to external factors such as subcontractors and suppliers. Improving supply chain management can help yards better understand their production enterprises and these insights can be used to optimize processes and facilities. A key element to improve the efficiency of ship repair supply chain is to improve the integration of, organizations operating within a supply chain. Describing Shiprepair in a nutshell it would right to say that: - 8 - --------_1 "There are known knowns. There are things we know that we know. There are known unknowns. That is to say, there are things that we now know we don't know. But there are also unknown unknowns. There are things we do not know we don't know" 1 and Shiprepair is full of unknown unknowns, the thesis attempts to identify a few.

Thesis submitted in fulfilment of the requirements for the degree Master Technologiae: Chemical Engineering In the Faculty of Engineering at Cape Peninsula University of Technology
Most biodiesel plants operate batch-wise using homogeneous alkali catalysts. Recently, several heterogeneous catalysts have been suggested in literature, as they have shown potential for overcoming most of the challenges associated with the application of homogeneous catalysts. Previous published techno-economic comparisons of the two technologies on large-scale processes located in the developed world, have revealed the economic superiority of heterogeneously catalysed processes. Hence, prospect exists for current homogeneously catalysed process plants to be converted to heterogeneously catalysed ones. The objective of this research was to investigate the actual cost benefit of converting a small-scale batch biodiesel plant from homogeneous to heterogeneous catalysed process. For this purpose, a small-scale batch biodiesel plant located in South Africa was taken as the base case homogeneous process. Aspen Batch Process Developer® software was used to perform the process simulations. The homogeneous process was converted to the heterogeneous one and results from process simulation were used to evaluate the economics of both processes, which were compared in terms of fixed capital cost, total manufacturing cost and profitability indicators. During economic evaluation, two types of cost factors were used: one prevailing in developed world and the other one relevant to South Africa. The sensitivity analysis of both processes was further performed in order to investigate the impact of some uncertain parameters on their profitability. Finally, a debottlenecking study was carried out. Results obtained from this study showed an increase in the annual throughput of biodiesel as well as significant savings in the total capital cost for the heterogeneous catalysed process relative to the homogeneous one. As regards the estimation of the total unit manufacturing cost of biodiesel, significant differences arose when using the two types of cost factors. Results of economic analyses estimated using cost factors relative to South Africa suggest an increase in the unit manufacturing cost of biodiesel while using the developed world’s cost factors suggests the opposite. This is due to the higher raw material and energy requirement for the CaO process, while knowing that the direct costs are a bigger proportion of the manufacturing costs estimated using the South African cost factors. Profitability and sensitivity analyses only provided positive results when estimated using the South African cost factors. In all cases, the heterogeneous catalysed process was found to be more promising than the homogeneous one over the prescribed project life. The study showed the importance of using cost factors relevant to a particular economic environment during techno-economic assessment of a process. It was also shown that there are economic benefits when replacing settling with centrifugation in biodiesel production processes. In summary, this thesis makes some important contributions. It presents the first process simulation for biodiesel production using Aspen Batch Process Developer® software and thereby proposes a methodology that is currently scarce in the literature. It also reports the first techno-economic analysis applied to the biodiesel field in South Africa and provides a preliminary insight to owners of biodiesel plants as regards the decision to convert or not their homogeneous catalysed plant to heterogeneous one.

This research explored the extent to which different knowledge conversion processes require different kinds of leadership. The research was inspired by Nonaka and Konno (1998) and proposed that knowledge conversion processes may each require their own form of leadership because they are conducted under different bas or contexts. Vera and Crossan's (2004) work provided a foundation for this research through the argument that knowledge conversion processes need not only transformational but also transactional leadership. The leadership framework based upon transformational and transactional leadership was therefore adopted for the study. Semi-structured interviews and the Multifactor Leadership Questionnaire (MLQ), developed by Bernard Bass and Bruce Avolio to assess leadership under the transformational and transactional leadership framework, were used to gauge the opinions of participants about leadership and knowledge conversion processes. Scenarios/descriptions derived from Nonaka and Takeuchi (1995) were used to focus the mindset of the participants involved in the interviews and the questionnaire, which was administered at the time of the interviews to support triangulation. Findings suggested that knowledge conversion processes do not differ to the extent that they require both transformational and transactional leadership. However, qualitative evidence indicated that knowledge conversion processes were somewhat different in terms of certain dimensions of transformational leadership. These differences related to the need for a strong sense of purpose, a compelling vision of the future and long-termism in some but not all situations involving the leadership of knowledge conversion processes.

Syftet med detta examensarbete är att effektivisera monteringsprocessen genom att hitta en lämplig produktionslayout i den gemensamma monteringsavdelningen. Rapporten bygger på följande frågeställningar: 1. Hur fungerar den befintliga produktionslayouten för de fyra olika teamen? 2. Vilken/Vilka kriterier kan påverka effektiviteten i den gemensamma monteringsavdelningen? 3. Hur ser ett förslag till en ny produktionslayout ut som tar hänsyn till dessa kriterier? Frågeställningarna besvaras med hjälp av en fallstudie som gjordes på företaget. Data samlades in genom intervjuer med berörd personal inom det undersökta området och observationer gjordes i produktionslokalen. Studier av grundläggande teorier inom produktionslogistik bygger ett teoretiskt ramverk för hela rapporten och ger stöd till genomförandet av projektet. I undersökningen studeras plockningsprocess och omställningsprocess extra noggrant för att kunna minska tidsåtgången för dessa arbeten. Resultatet visar att Garo har lagt upp sina produktionsresurser på ett sätt så att det blir smidigt för montörer att genomföra sitt arbete. Företaget producerar en stor mängd varianter för att tillfredsställa marknadens efterfrågan. Orderkvantiteterna är oftast små och monteringen sker antingen mot lagerorder eller mot kundorder. Ca 50% av produktionen sker mot kundanpassade ordrar. Enligt observationer är den befintliga produktionslayouten i de fyra monteringsteamen av den cellbaserade typen, där varje arbetsbänk motsvarar en produktionscell. Enligt teorin av de sju produktionssystemen skall denna layout passa utmärkt för företags verksamhet med hänsyn till sina omväxlande produktmodeller och rekommenderas därför att behållas. Anledningen till att den inte bidrar till den önskade effektiviteten i monteringsteamen är att det har funnit slöserier som genereras av icke värdeskapande aktiviteter i arbetsprocessen. De största slöserierna identifierats i monteringsprocessen är väntan, onödigt lager och onödig transport. För att öka effektiviteten i monteringsteamen måste företaget eliminera slöserierna genom att:  Effektivisera plockningen  Skapa bättre flexibilitet på arbetsbänkarna  Rationalisera efterarbete i omställningen

A primary algorefinery, concept that deals with the main components of microalgae (lipids, proteins, carbohydrates and pigments), has been studied. A sequence of unit operations has been implemented in order to obtain separated enriched fractions of these biomolecules by conserving their integrity in the downstream process. The study was mainly centred on Chlorella vulgaris, a species known for its rigid cell wall. Most of the lipophilic fraction (lipids and pigments) was recovered using supercritical carbon dioxide with ethanol as a co-solvent, without a preliminary unit operation of cell disruption. The hydrophilic fraction (proteins and polysaccharides) was recovered in the aqueous phase after bed milling as cell disruption method. Subsequently, the aqueous phase was fractionated into three fractions by means of a process of two-stage ultrafiltration. Thus, starches, pigments, proteins and sugars were successfully separated from each other. A life cycle assessment will be necessary to estimate the cost and the sustainability of the fractionation process.

Agricultural residues and energy crops constitute an important part of the energy chain although they are not being used extensively in the energy generation processes since they are associated with disadvantages such as low bulk and energy densities and handling problems. One solution is the pelletisation of these residues, which solves a great deal of these problems and enables the competition of biomass with other types of fuels. A large amount of work, concerning the combustion of biomass pellets, has been done previously, however, studies on biomass pellet gasification are still limited. An effort is made, in the current project, to connect the pelletisation and the gasification processes so that the work presented here could constitute a guide to the industry. The quality of the pellets to be gasified is affected by the initial pelleting parameters, namely the feedstock moisture content, the feedstock particle size and the die diameter. These parameters in turn, affect the process of gasification. These relationships were studied with the purpose of finding an optimum behaviour in the pelleting process that would allow high efficiencies of pellet gasification. The agricultural residue investigated was oilseed rape due to high cultivation in the UK. Oilseed rape straw (OSRS) was pelletised and used in two types of gasifiers; a downdraft and a spouted fluidised bed gasifier. Other types of biomass pellets such as Miscanthus pellets and Dried Distillers Grains with Solubles (DDGS) pellets were also studied. The gasification performance of the OSRS pellets was compared with the performance during gasification of Miscanthus and DDGS pellets. The results showed that dry and large pellets required more energy to be manufactured than the wet and small pellets. In addition, the results revealed the connection of the initial pelleting parameters and the quality of pellets which was assessed in terms of the pellet density, the bulk density and the pellet durability. The wet pellets with a small particle size had the highest density and the dry pellets had the highest bulk density and durability. The effect of the initial pelleting parameters on the gasification was also studied. It was found that the high feedstock moisture content negatively affected the gasification performance in both downdraft and spouted fluidised bed gasification. The feedstock particle size did not have an effect on the downdraft gasification but a minor effect was identified for the spouted fluidised bed. Large pellets were unable to be processed in the downdraft gasifier due to the increased bed porosity and pellet density and decreased amount of active carbon sites, while both large and small pellets were successfully processed in the spout bed gasifier. The gas higher heating value (HHV) produced in gasification was typically quite low, of between 2-4 MJ/m3. The comparison of the pellets showed that Miscanthus pellets had the highest gasification performance followed by the dry OSRS pellets, the wet OSRS pellets and finally the DDGS pellets. The most important reason for these differences was identified to be the ash content of the pellets.

This thesis is a study of the changing relationship over time (1856-1990) between the Rishi, an ex-Untouchable jati of Bengal/South-West Bangladesh, and various groups of Catholic missionaries. The material consists of intensive ethnographic fieldwork among Hindu and Christian Rishi, as well as research into historical sources on missionary presence. The new approach to mission initiated by Vatican II (1962-65) is contrasted with the phenomenology of dialogue as this occurs in the field. A common ground is established between this stance and recent anthropological theory intent on solving authorial crisis by adopting 'dialogic' styles. It is argued that the mere adoption of a dialogic genre does not provide a solution for textual authority in anthropology, nor does it solve the missionary impasse. The radicality of dialogue as an ethical involvement rather than a means to an end (either 'conversion' or epistemological certainty) or as a methodological tool, is further analysed through the tensions inherent in the 'translation' of the Christian message. The misunderstandings this generates and the variety of missionary positions vis-a-vis the Rishi and the wider society constitute the 'topoi' of multiple dialogues. The Rishis' experience of 'Untouchability' and their struggle for humanity expose the shortcomings of a missionary self and the possible hidden intentionalities of anthropological enquiry. The field situation of the missionary and the ethnographer alike provide a testing ground for theories of dialogue in modern philosophy. It is argued that it is principally in the Levinasian 'proximity to alterity' and the Gramscian concept of 'counter-hegemony' that dialogue becomes ethically and politically demanding, and that social anthropology, as a discipline interested in human dialogue and its tensions, cannot fulfil its vocation without making an ethico-political commitment.

ENGLISH ABSTRACT: The sugar industry over the years has been producing sugarcane bagasse as part of the sugar milling process. Currently this sugar mill biomass is incinerated inefficiently as a means of their disposal to produce steam and electricity, which in most cases are only just enough to supply the energy required to run the mills, thereby leaving very little or no extra energy for sale to bring in extra income in addition to sales revenue from sugar. However, the recent instability and uncertainties in the price of sugar and the global call for a green and sustainable environment have necessitated the search for ways of making effective use of this biomass to supply sugar mill energy demands, while producing extra energy in the form of electricity and other energy products for sale and at the same time contributing towards environmental sustainability. The main objective of this work was to develop process models for the processing of sugar mill biomass into energy and energy products. Based on this, biomass to energy conversion process (BMECP) models have been developed for various process configurations of two thermochemical processes; Combustion and Fast Pyrolysis using the Aspen Plus® simulation software. The aim of process modelling was to utilizing sugar cane bagasse as an input energy source to supply the energy requirements of two sugar mill configurations (efficient and less efficient mills), while generating extra electricity and high valued energy products for sale. Four BMECP configurations; 30bar BPST, 40bar CEST, 63bar CEST and 82bar CEST systems were modelled for the combustion thermochemical process. For the fast pyrolysis thermochemical process, two process configurations: Pure Fast Pyrolysis BMECP and Partial Fast Pyrolysis BMECP were modelled. The former BMECP utilizes all available bagasse through fast pyrolysis to produce bio-oil and biochar alongside generating electricity as well as energy to run the sugar mill operations. In the latter BMECP model, only surplus bagasse after separation of the quantity needed to supply the sugar mill energy requirement and electricity production is used to produce bio-oil and biochar. The technical performance of the BMECP models have been analysed and compared based on steam and electricity production rates, process efficiencies and environmental impacts (based on CO2 savings). The effects of boiler operating pressure and bagasse moisture content on the performance of the combustion based BMECP models have also been investigated. Finally, detailed economic models have been developed using the Aspen Process Economic Analyzer (Icarus®) to assess the economic viability of the BMECP models and sensitivity analysis performed to study the response of the BMECP models to variations in economic parameters. Technical performance analysis shows the combustion based BMECP models perform better than the Pure Fast Pyrolysis and Partial Fast Pyrolysis BMECP models with regards to steam and electricity production, thereby giving them higher electrical efficiencies. The electricity generation rate has been shown to increase with increasing boiler operating pressure and decreasing bagasse moisture content while steam production rate has been shown to increase with decreasing bagasse moisture content and decreasing boiler operating pressure. Despite the lower electrical efficiencies of the fast pyrolysis based BMECP models, the analysis shows that their overall process efficiencies compare very well with those of the combustion based BMECP models due to the production of high energy value pyrolysis products. Based on common operating pressure and 50% bagasse moisture content, the Pure Fast Pyrolysis and the Partial Fast Pyrolysis models have proved to be more environmental friendly with hourly CO2 savings of 40.44 and 41.30 tons for the Partial Fast Pyrolysis BMECP and the Pure Fast Pyrolysis BMECP respectively based on a 300 ton of sugarcane/h (81 ton bagasse/h) plant size. From an economic point of view, biomass combustion based on the 63bar CEST BMECP model has proved to be the most economically viable option under current economic conditions. First order total capital investment estimate for this BMECP is about $116 million, producing NPV of $390 million at the end of a 20 year plant life and IRR of 34.51%. The Pure Fast Pyrolysis BMECP model is the least economic viable option. Sensitivity analysis shows this BMECP model is the most sensitive to changes in bagasse and electricity prices; recording -191.61/+446.86% change in NPV for a ±30% change in bagasse price and -91.5/+338.60% for a ±30% change in electricity price.
AFRIKAANSE OPSOMMING: Die afgelope jare het suikerriet-afval (bagasse) by suikermeule ‘n belangrik byproduk van die suiker-industie geraak. Tans word hierdie afval of biomasse verbrand in die suikermeule se poging om stoom en elektrisiteit op te wek; maar die die proses is oneffektief. Die hoeveelheid energie wat opgewek word, is skaars genoeg om die suikermeule self aan die gang te hou; daar is feilik geen sprake ‘n surplus energie waaruit ekstra inkomste verkry kan word toevoegend tot inkomste uit die suiker verkope self. Die huidige onstabiele suikerprys en gepaardgaande onsekerhede sowel as die werêldwye oproep vir ‘n groen- en volhoubare omgewing, noodsaak ‘n nuwe soeke na effektiewe manier om die afvalmateriaal sinvol te verwerk. Die tipe effektiwiteit van verwerking waarna gesoek word moet die volgende uitkomste hê: verskaffing van genoeg energie tydens produksie aan die suikermeuele self; vervaardiging van ekstra energie in die vorm van eletrisieteit en ander energie produkte. Terselfder moet die ook bydra tot die volhoubaarheid van die omgewing. Die grootste gedeelte van hierdie navorsing is gewy aan die ontwikkeling van “proses modelle” om suikemeule afval (bagasse) te omskep in energie en energie-produkte. Om hierdie doel te bereik, is biomassa-tot-energie omskeppingsproses- modelle (BMECP) ontwikkel om verskeie proses konfigurasies van twee termo-chemiese prosesse, naamlik Verbranding (Combustion), en Vinnige Pirolise (Fast Pyrolysis) deur die gebruik van die ‘Aspen Plus®’- simulasie sagteware. Die doel van die proses modelering was om suikerriet biomassa as ‘n bron van energie te gebruik om weer die energie benodighehede van twee denkbeeldige suikermeule vas te stel; een meul is voorgestel as effektief, die ander as minder effektief. Terselfdertyd is gekyk na die hoeveelheid ekstra energie wat elkeen sou opwek en ander hoogs waardevolle energie produkte om te verkoop (bv. ‘bio-olies en bio-char’). Vier “BMECP” konfigurasies (voorstellings) 30bar BPST, 40bar CEST, 63bar CEST en 82bar CEST sisteme is gemodelleer vir die Verbranding termo-chemiese proses. In die geval van die Pirolise (Pyrolysis) termo-chemiese proses, is twee proses konfigurasies gemodelleer: 1. Suiwer Vinnige Pyrolyise BMECP en 2. Gedeeltelik Vinnige Pirolise BMECP. In die geval van eersgenoemde, word alle beskikbare ‘bagasse’ deur vinnige pirolise omskep om ‘bio-olie’ en ‘bio-char’ te vervaardig.Verder wek dit ook elektrisiteit op so wel as die nodige energie om die suikermeule te laat opereer. In die geval van die Gedeeltlike Vinnige Pirolise BMECP , moet daar eers genoegsame ‘bagasse’ opsy gesit word om die suikermeule van genoegsame energie te voorsien vir die volle funskionering daarvan en elektrisiteit-opwekking. Van die surplus of oorblywende ‘bagasse’ kan dan gebruik word om ‘bio-olie’ en ‘biochar’ te produseer. Die tegniese prestasie van al die BMECP modelle is geanaliseer en vergelyk ten opsigte van stoom en elektrisiteits-opwekking; proses effektiewiteit asook die impak op die omgewing ( gebaseer op CO2 –besparings). Die effek van stoomkettel-druk tydens operering asook die bagasse se vog-inhoud. Op die prestasie van die verbrandingsgebaseerde modelle is ook ondersoek. Laastens, uitgebreide ekonomeidese modelle is ook ontwikkel deur die gebruik van die ‘Aspen Process Economic Analyser (Icarus®)’. Sodoende is die ekonomiese vatbaarheid van die BMECP modelle ondersoek. Hierdie sagteware help ook met. Sensitiwiteits-analise in die bestudering van die terugvoer van die BMECP modelle tot veranderlikes in ekonomiese parameters. Rakende effektiwiteit, toon die uitslae dat die verbrandings-gebaseerde BMECP modelle beter vaar as die met betrekking tot stoom- en elektrisiteits-opwekking. Verbrandings-gebaseerde-modelle toon hoër elektriese effektiwiteit. Indien die vog-inhoud van die bagasse laag was en die tempo van stoomketel operasie druk verhoog is, het die tempo van elektriesiteits-opwekking ook gestyg. Ten opsigte van stoom daarenteen, het die stoom-opwekking tempo verhoog in die die vogl inhou van diebagasse laag was asook verminderde stoomketel operering druk. Ten spyte van die laer elektriese effektiewiteit van die Suiwer Vinnig- en Gedeeltelik Vinnig BMECP modelle, dui die analise aan dat hul proses effektiewiteit in die geheel Goed vergelyk met die van die verbrandings-gebaseerde BMECP modelle. Dit is toe te skryf aan die produksie van die hoë-energie draende pirolise produkte. Gebaseer op algemene operering druk van 50% ‘bagasse’ vog-inhoud, het die bogenoemde twee modelle bewys om meer omgewings-vriendelik te wees met uurlikse CO2-besparings. In die geval van Gedeeltelike Vinnige Pirolise BMECP, 40.44 en vir die Suiwer Vinnige Pirolise BMECP 41.30 gebaseer op ‘n 300 ton suikerriet/h (81 ton bagasse/h) plantasie-grote. Ten slotte, vanuit ‘n ekonomiese oogpunt, blyk ‘n biomassa verbranding gebaseer op die 63 bar CEST BMECP model die mees ekonomies-vatbare opsie onder huidige ekonomiese omstandighede. Eerste orde totale kapitale belegging beraming vir hierdie BMECP is ongeveer $116 miljoen, produksie NPV is $390 miljoen aan die einde van ‘n 20 jaar tydperk vir ‘n suikerriet-aanleg. IRP is 34.51%. Die Suiwer Vinnige Pirolise BMECP is die mins-ekonomiese vatbare model. Sensitiewiteits-analises het getoon dat hierdie BMECP model baie sensitief is ten opsigte van verandering in die pryse van bagasse en elektrisieteit; in die geval van NPV is veranderinge van -191.61/+446.86% aangedui op ‘n ±30% verandering in bagasse pryse. In die geval van elektrisieteitspryse, is ‘n sensitiewiteit van van -91.5/+338.60% op ‘n ±30% prysverandering getoon.

This paper presents the research results of treatment solution of wood waste of Acacia and Eucalyptus in making of bioorganic fertilizers for the effective utilization of plant biomass resources and minimization of environmental pollution. The conversion cycles of the basic chemical compounds of wood waste in composting process were established by two biological products: Biomix and Compost Maker. Research results have shown that, under the action of microorganisms, all basic chemical compounds were modified (among them cellulose was most powerfully modified) whereas lignin, extractives dissolved in ethanol were less destructed. Within about first 75 days of composting, the conversion of the above mentioned compounds is negligible. With the time of composting from 105 days to 120 days, in total over of 70% of cellulose was conversed into compounds dissolved in water and in 1% NaOH solution. The optimal composting time was about 105 days. In this case, the fertilizer obtained was humified, had dark colour and could be used for planting and soil improvement purposes
Bài báo này trình bày các kết quả nghiên cứu giải pháp xử lý mùn vụn gỗ phế thải của gỗ Keo và Bạch đàn thành phân bón hữu cơ vi sinh, nhằm tận dụng hiệu quả nguồn sinh khối thực vật và giảm thiểu ô nhiễm môi trường. Đã xác lập được một số quy luật biến đổi của các thành phần hóa học cơ bản của mùn vụn gỗ trong quá trình ủ compost bằng hai chế phẩm vi sinh Biomix và Compost Maker, để tạo phân bón hữu cơ vi sinh. Kết quả nghiên cứu đã cho thấy, dưới tác dụng của vi sinh vật, tất cả các thành phần hóa học cơ bản của mùn vụn gỗ đều bị biến đổi, trong đó xenluloza bị biến đổi mạnh nhất, lignin và các chất trích ly bằng etanol ít bị phân hủy hơn. Trong vòng khoảng 75 ngày ủ đầu tiên, sự biến đổi của các thành phần nêu trên là không đáng kể. Với thời gian ủ từ 105 ngày đến 120 ngày, tổng cộng có trên 70% xenluloza bị phân hủy thành các hợp chất dễ tan trong nước và dung dịch NaOH 1%. Thời gian ủ thích hợp là khoảng 105 ngày. Trong trường hợp này, phân bón thu được đã bị mùn hóa, có mầu sẫm và có thể sử dụng cho mục đích trồng trọt và cải tạo đất

Conversion, the process by which natural uranium ore (yellowcake) is purified and converted through a series of chemical processes into uranium hexafluoride gas (UF6), has historically been excluded from the nuclear safeguards requirements of the 235U-based nuclear fuel cycle. With each step in the conversion process from yellowcake to feedstock for UF6, intermediary uranium oxide and uranium fluoride compounds become progressively attractive products for diversion toward activities noncompliant with international treaties. The diversion of this product material could potentially provide feedstock for a clandestine or undeclared enrichment for weapons development for state or non-state entities. With the realization of this potential, the International Atomic Energy Agency (IAEA) has only recently reinterpreted its policies to emphasize safeguarding this feedstock in response to such diversion pathways. This project employs a combination of simulation models and experimental measurements to develop and validate concepts of nondestructive assay monitoring systems in a natural uranium conversion plant (NUCP). In particular, uranyl nitrate (UN) solution exiting solvent extraction was identified as a key measurement point (KMP), where gamma-ray spectroscopy was selected as the process-monitoring tool. The Uranyl Nitrate Calibration Loop Equipment (UNCLE) facility at Oak Ridge National Laboratory was employed to simulate the full-scale operating conditions of a purified uranium-bearing aqueous stream exiting the solvent extraction process in an NUCP. This work investigates gamma-ray signatures UN circulating in the UNCLE facility and evaluates various gamma-ray detector (HPGe, LaBr3 and NaI) sensitivities to UN.

Thesis (MTech (Chemical Engineering))--Cape Peninsula University of Technology, 2017.
One of the very promising synthetic fuel production strategies is the Fischer-Tropsch process, founded on the Fischer-Tropsch Synthesis, which owes its discovery to the namesake researchers Franz Fischer and Hans Tropsch. The Fischer-Tropsch Synthesis (FTS) converts via complex polymerisation reaction a mixture of CO and H2 over transition metal catalysts to a complex mixture of hydrocarbons and oxygen containing compounds with water as major by-product. The mixture of CO and H2 (termed syngas) may be obtained by partial oxidation of carbon containing base feedstocks such as coal, biomass or natural gas via gasification or reforming. The Fischer-Tropsch (FT) process thus presents the opportunity to convert carbon containing feedstocks to liquid fuels, chemicals or hydrocarbon waxes, which makes, for instance, the monetisation of stranded gas or associated gas a possibility. The FT-process is typically carried out in two modes of operation: low temperature Fischer-Tropsch (LTFT) and high temperature Fischer-Tropsch (HTFT). LTFT is normally operated at temperatures of 200 – 250 °C and pressures of 10 – 45 bar to target production of high molecular weight hydrocarbons, while HTFT is operated at 300 – 350 °C and 25 bar to target gasoline production. The catalytically active metals currently used commercially are iron and cobalt, since product selectivity over nickel is almost exclusively to methane and ruthenium is highly expensive in addition to requiring very high pressures to perform optimally. Fe is much cheaper, but tends to deactivate more rapidly than Co due to oxidation in the presence of high H2O partial pressures. One of the major drawbacks to using Fe as FT catalyst is the requirement of lower per pass conversion which necessitates tail gas recycle to extend catalyst life and attain acceptable overall conversions. A more active or similarly active but more stable Fe-catalyst would thus be advantageous. For this reason promotion of a self-prepared typical LTFT Fe-catalyst with Ru was investigated. A precipitated K-promoted Fe-catalyst was prepared by combination of co-precipitation and incipient wetness impregnation and a ruthenium containing catalyst prepared from this by impregnation with Ru3(CO)12. The catalysts, which had a target composition of 100 Fe/30 Al2O3/5 K and 100 Fe/30 Al2O3/5 K/3 Ru, were characterised using XRD, SEMEDX, ICP-OES, TPR and BET N2-physisorption, before testing at LTFT conditions of 250 °C and 20 bar in a continuously stirred slurry phase reactor.

The conversion of synthesis gas to desirable liquid fuels in gasoline and diesel range in a single reactor process with simultaneous use of FT and cracking catalysts was investigated in this dissertation. Co-based catalyst and ZSM-5 were used as a FT and cracking catalysts, respectively. The structural and textural properties of ZSM-5 were analyzed by XRD, BET and particle size analysis. Following, commercially available FT and cracking catalyst were tested in the newly designed fixed bed dual-zone reactor under 350 psi; syngas with H2/CO ratio in the amount of 2, and flow rate of 70, 100 and 130 smL/min; and 0.5, 1.25 and 2.5 g of ZSM-5. The temperature for the FT Co-based catalyst was maintained constant at 190 °C, whereas, the temperature for the additionally implemented cracking catalyst was varied (250, 300 and 350 °C). The effect of operating reaction conditions such as syngas flow rate, Si/Al molar ratio; temperature and loading of cracking catalyst were investigated. It was shown, that in general, decrease of syngas flow rate, ipso facto increase in residence time, resulted in decrease of gasoline and diesel fuel production, whereas reduction of ZSM-5 loading improved the formation of C5 - C17 paraffins. An enhancement in gasoline and diesel paraffin range formation was also observed with the decrease of cracking temperature. In addition, the effect of variation in operating conditions was evaluated for liquid paraffin production and dominance of chain propagation reactions over cracking and/or isomerizarion reactions with cracking catalyst loading and syngas flow rate was observed. As a consequence, the results employing ZSM-5 showed increased formation of light hydrocarbons and aromatics; and reduction of heavier paraffins production. Finally, the effect of various Si/Al molar ratios in the amount of 50, 80 and 280 were studied in this research. It was found, that the decrease in acidity of ZSM-5 zeolite enhanced the selectivity towards desirable products as well as heavier paraffins, but suppressed the formation of CH4. Furthermore, the isomerization reactions became favored in expense of cracking reactions.

Thesis (Master of Engineering in Mechanical Engineering)--Cape Peninsula University of Technology, 2018.
The present study was centred on the design of a thermal multistage solar still desalination system. The design is a multistage with new configurations such as direct vapour input into each stage using vapour make-up tubes and the integration of a multistage with a basin type solar still. The incorporation of float a valve in the secondary seawater tank to regulate the seawater in the assembly eliminated the need of pumps to the system. The circulation of seawater between the evaporator and the evacuated tube solar collector (ETC) was through the pressure difference and the flow back was controlled through the incorporation of oneway flow valve. The ETC was used as a heat source to supply the thermal energy into the multistage system. The system had no electrical connections and therefore, no forced circulation as no pumps or any electrical components were used. The system consisted of six stages in total, the evaporator supplied the vapour to five of the six stages of the system. The system was tested on the roof of Mechanical Engineering Department and this location was chosen because of less sun’s intensity obstructions. The system was tested for nine (9) days but the distillate collection was not performed for the whole each day. This was due to the controlled access to the roof and the minor repairs that had to occur before the tests were conducted. The duration on which the tests were conducted varied in each day. The data was supposed to be logged from 08h00 am to 18h00 pm but this was not so due to the controlled access to where the tests were conducted. This data logging period was chosen based on the assumptions that the sun’s intensity would be at maximum within this period. The longest period of test was approximately 7 hours and the system managed to produce about 1500 ml and the maximum temperature for the day was 28oC. The system produced a minimum of 225 ml in the space of 3 hours and the temperature of the day was 26oC. The total amount of distillate produced was about 7600 ml and this amount was produced within the period of 49 hours. The 49 hours is equivalent to two days and 1 hour. It is anticipated that the system would have produced more should there be no repairs involved during the tests. The system produced a maximum of 48 ml at night and a minimum of 8ml in some nights. The night tests were not controlled and monitored due to limited access. It was noticed that the system was empty in each morning of the first few days of the tests. This emptiness contributed to the leakage occurred to the evaporator. The leakage of the evaporator was caused by unmonitored heat supplied by the ETC. The evaporator was constructed using unsuitable material and this was another factor which contributed towards the failure of the evaporator.

The production of municipal solid waste has continued to grow in recent years. In Italy, municipal solid waste production reaches about 29 million tons per year. The organic fraction of municipal solid waste (OFMSW), which accounts for 30-40% of the total waste, usually undergoes biological treatments such as anaerobic digestion or composting, or is incinerated or landfilled. Biological treatments are considered not economically viable due to the long processing time (20-30 days), while incineration and landfilling are considered as low cost but polluting processes. In contrast, Hydrothermal Carbonization (HTC) is a cost-effective process to treat organic waste especially for the shorter processing time (0.5-8 h) and the possibility to treat directly wet heterogeneous materials. This thesis aims to investigate the potential use of HTC to upgrade OFMSW and other biomasses to biofuels or valuable byproducts. Chapter 1 gives an overview on the state of the art of HTC technology applied to organic wastes, focusing both on mechanisms and on the characteristics of reaction products. Chapter 2 investigates the potential use of HTC to upgrade the organic fraction of municipal solid waste (OFMSW) into biofuel and byproducts. The impact of process conditions (process time, temperature and solid load) on the formation, chemical and energy properties of hydrochar was deeply investigated. To analyze the behavior of hydrochar as a solid biofuel, the combustion (oxidation) of hydrochar and the co-firing (co-oxidation) of hydrochars and coals was also investigated. The results show that, especially at HTC harsher conditions, hydrochar is a “coal-like” material, that can be used as a valuable solid biofuel. The results evidenced that hydrochar is composed of primary char and secondary char. Primary char (non-extractable with organic solvents) has characteristics similar to coal and could be recovered for combustion, while secondary char is an amorphous and more volatile solid, easily extracted with organic solvents, which found possible application as a source of biochemicals and liquid bio-fuel. Chapter 3 investigates the use of HTC as a promising pre-treatment to enhance the biomethane potential during anaerobic digestion of OFMSW. Anaerobic digestion experiments were carried out using the HTC process liquid and the entire HTC reaction mixtures. Results proved that, when compared to the raw OFMSW, the use of HTC liquid and HTC mixture into AD lead to an increase of biomethane production of up to 37% and 363% by volume, respectively. Chapter 4 reports an HTC kinetics study and a kinetic model, which accounted for reactions leading to the production of primary and secondary char, as well as the liquid and gas phases. The model was optimized using experimental data performed on a lignocellulosic feedstock (olive trimmings) and validated on two other types of biomasses (grape marc and Opuntia Ficus Indica) and was used as a reliable tool to predict the carbon distribution among HTC products. In this chapter an in-depth analysis was also carried out to understand the evolution of feedstock characteristics during the heat-up transient phase before reaching the HTC set-point temperature. The results show that during heat up, the feedstock carbonized to a considerable extent at 220-250 °C. Tests clearly show evidence of the transition between thermal hydrolysis and HTC. Chapter 5 presents a study conducted to evaluate the economic feasibility and the detailed energy and cost analyses of a hypothetical HTC plant transforming wet biomass into pelletized dry hydrochar. To achieve these goals, a model was developed on the basis of experimental results obtained previously on two other organic materials (grape marc and off-specification compost). The results show that, when operating the HTC plant with grape marc at the optimal HTC conditions (T=220 °C, t=1 h, dry biomass to water ratio=0.19), the production cost of hydrochar were determined to be 157 €/ton, competitive with the price of wood pellets (150-200 €/ton). This makes HTC a promising process for a large development at the industrial scale.

Thesis (DTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2016.
The water desalination process needs large quantities of energy, either directly from fossil fuel or electricity from the national grid. However, these sources of energy significantly contribute to problems such as global warming in addition to creating a drain on the economy, due to their high cost. This dissertation is a description of the research undertaken with the aim of producing a water desalination prototype; a novel approach that was designed using state-of-the-art solar water heating equipment, incorporating the technologies of evacuated tubes and heat pipes. During the execution of the project, various modifications to the original commercially-available solar water heating system were attempted, each aimed at increasing the production of pure water. Finally, the system proved capable of producing a reasonable amount of pure water after twelve lengthy indoor experiments conducted in a laboratory in the department of Mechanical Engineering at the Cape Peninsula University of Technology, Bellville Campus, Cape Town, South Africa. Each experiment lasted five days on the basis of seven hours of exposure to an average amount of simulated solar radiation, followed by seventeen hours daily of inactivity and partial cooling down of the system.

The production of both fresh water and waste streams are progressively increasing over the years due to ongoing population growth coupled with high levels of increase in water consumption. The ongoing growth of human activities, such as industry, recreation, and agriculture, are significantly contributing to the increase in both water demand and severity of degradation of natural water resources. The majority of the industrial wastewaters have a significant impact on the environment; some of which may pose a number of threats to human health and the surrounding environment. Thus, discharge of such waste streams into a surface water and/or groundwater presents a major source of water pollution in many countries. Therefore, these waste streams must be disposed of in an environmentally acceptable manner. The primary concern of the PhD thesis is to seek the most feasible and applicable freezing desalination technologies that are potentially capable to concentrate the dissolved ionic content of the liquid streams, especially for those causing severe pollution problems. Therefore, various forms of melt crystallisation processes, namely; agitated and static crystallisation processes, ice maker machines, a Sulzer falling film crystallisation process, the Sulzer suspension crystallisation process, and the Sulzer static crystallisation process, were experimentally used and investigated. The experimental investigations were carried out on the laboratory bench scale and/or straightforward pilot plant by using aqueous solutions of sodium chloride and/or process brines as feed samples. The study was focused on a number of important parameters influencing the separation performance of the investigated treatment systems. In general, the resulting experimental data for each innovative process were highly encouraging in minimising the volume of the waste stream, and substantially increasing the amount of product water. The obtained product water was ready for immediate use either as drinking water or as a saline water of near brackish water or seawater qualities. Also, relationships between the influences and the separation performance, in terms of salt rejection and water recovery ratios, were explored and determined for the investigated technologies. Based on the experimental results, the Sulzer melt crystallisation processes were scaled up and were combined into a commercial reverse osmosis membrane desalination plant. As a result, three novel treatment option configurations were proposed for minimising the waste stream, whilst increasing the production rate of drinking water and/or preserving a substantial amount of natural water resource from the RO plant's exploitation.

The Swedish Migration Agency has, through the years, received criticism regarding its management and assessments of different cases. One of these critiques has been towards the Agency’s management of asylum seekers claiming to have converted as a refugee claim. Therefore, this thesis aims to strengthen the Agency’s management of these cases. Using the critisism made against the Swedish Migration Agency, I suggested recommendation and amendments to the Agency’s established guidelines. The findings in this thesis showed extensive criticism towards the Agency’s usage of religious knowledge tests to assess the genuineness of a conversion. The critic also argues that the Agency lacks religious understanding and that the Agency should focus on identity, community, and faith in a higher power. The analysis presented a need to address religion, the conversion process, and the role of the Agency’s personnel in the guideline.

Thesis (MEng (Chemical Engineering))--Cape Peninsula University of Technology, 2020
South Africa currently faces an energy security issue with regards to the country’s rather insignificant petroleum reserves. The Fischer-Tropsch Synthesis process has found great application in converting the reserves available to products of economic value in terms of fuels and chemicals finding the adequate application at Sasol and Petro SA alike. However, in the realisation of the fact that coal is a high pollutant and natural gas reserves at a critical low with Sasol and Petro SA respectively, new innovations have become of critical importance. Solid waste management has become an ever-growing problem world-wide due to rapid urbanization and population growth. South Africa was found to have generated 9 million tons of general waste in 2011 with the Western Cape generating 675 kg/capita/annum. The convention of management has been that of landfilling however, this method is fast becoming insignificant due to the lack of space and detrimental nature to the environment. Considering the energy security issue South Africa is facing, and the global drive of finding alternate sources of fuel with the depletion of fossil fuel, attention has turned to MSW as a sustainable source of energy while remediating its effect on the environment. Thermochemical conversions of Municipal Solid Waste (MSW), this presents an attractive means of harnessing the potential value in this waste stream thus thermochemical conversion poses an attractive means of converting this waste stream into valuable fuel products. In the realisation of the 2 problems of energy security and solid waste disposal, Biomass to Liquid (BTL) technology was found to be the most suitable to tackle these issues. BTL is an established process that uses the thermal conversion of biomass into various liquid fuels products through a series of technologies. MSW is highly heterogeneous which poses a processing challenge, unlike virgin biomass which is normally used in BTL technologies. The study investigated the production of high-quality syngas through an Aspen simulation of thermal gasification which would be suitable for liquid fuels and chemicals via Fischer-Tropsch synthesis to bridge the energy security issue in South Africa. As the study also possesses an environmental facet, it was necessary to assess the pollution load caused by the process of landfilling in terms of Heavy Metals and Radionuclides which will be determined by means of radionuclide analysis and heavy metal analysis. The procedures were accomplished by use of the gamma-ray spectroscopy, High Purity Germanium detector, (HPGe) and Inductively Coupled Plasma Optical Emission Spectrometry, (ICP-OES) methods. The study was conducted by making use of Refuse Derived Fuel (RDF) pellets produced from the MSW. 4 Different binders in form of corn starch, guar-gum starch, waste palm oil and waste engine oil were used in the production of the pellets, thus the effect of this on energy content and thermal degradation behaviour was studied. The energy content of MSW in Cape Town was investigated using a bomb calorimeter and the thermal degradation behaviour was studied using Thermogravimetric Analysis (TGA). The South African Government, through the National Development Plan of South Africa, aims to provide access to the grid and off-grid electrical power to a minimum of 95 % of the population by 2030, of which 20 GW of the required 29 GW required for this needs to come from alternative and renewable energy sources. This study using the MSW from the City of Cape Town Municipality in South Africa shows that the MSW has a calorific value of approximately 19 MJ/kg which is significantly high, meaning that the waste can be directly used as fuel in many applications but more importantly that of electricity generation. The calorific value for the pelletised waste was found to be higher at an average of 23.9 MJ/kg which can be compared with South African coal being 25.1 MJ/kg. Using TGA, 3 distinguishable major mass loss regions were found between temperatures 55 – 265 ℃, 270 – 410 ℃ and 410 – 502 ℃. The total sample reduction was found to be more than 90 % on average which is a reduction of the waste. Heavy metals and Radionuclides (HM and R) are abundant in various types of municipal solid waste, including industrial waste, construction waste, medical waste, and household waste. Products containing HM and R are commonly disposed of in MSW or hazardous waste landfills and dumpsites. Approximately an average of 0.8 to 3 kg per capita per day of MSW is generated by suburban areas in South Africa. This method of managing or processing the waste has fast become inadequate and hence the need for new innovations. This has led to the focus on thermochemical conversion as an alternative. The soil is amongst the most considerable sources of radiation exposure to human beings and the migration for the transfer of radionuclides to the immediate environment. Exposure is a direct result of gamma-ray emissions that are produced by the most common terrestrial radionuclides, which are the member of the 238U and 232Th series and 40K of which concentrations differ with respect to the type of soil and the geology of the area. Environmental pollution by chemicals and heavy metals such as Cd, Ni, Zn, and Pb etc., showed a great increase in recent times due to various industrial operations including that of MSW disposal. All heavy metals at high concentrations have strong toxic effects and are regarded as environmental pollutants. Naturally occurring radionuclides activity was investigated at landfill sites from the City of Cape Town using a Hyper-Pure Germanium (HPGe) detector with appropriate shielding coupled to a Palmtop Multichannel Analyzer. Activity concentrations of the radionuclides 238U, 232Th and 40K were obtained from the activity concentrations of their respective daughter radionuclides. To obtain the overall combined effect in terms of activity concentration from the 3 parent radionuclides, the radium equivalent was calculated and 38.273, 41.019 and 83.007 Bq/Kg were obtained from Bellville, Coastal Park, and Vissershok respectively. Other radiological hazards in terms of Internal and External hazard indices and Representative hazard index were determined and found to be within safe limits. The dose rate in the air at 1m above the ground was determined to obtain a characteristic of the external gamma-ray and was found to be 17.490, 18.609 and 38.667 nGy/y for Bellville, Coastal Park, and Vissershok respectively. The health effects of the radiation in terms of annual effective dose and excess lifetime cancer risk were determined to be 0.031 mSv/y and 0.0961×10-3 which are lower than limits set by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) and the Nuclear Industry Association of South Africa (NIASA). The gasification part of the study was through process simulation models on ASPEN Plus Process simulation software. This investigation proposes a model of syngas creation from Refuse Derived Fuel (RDF) Pellet gasification with air in a fixed bed reactor. The model (utilizing Aspen Plus process simulation software) is utilized to model the anticipated results of RDF gasification and to give some processes fundamentals concerning syngas generation from RDF gasification. The fixed bed reactors are an updraft fixed bed reactor which can be divided into 3 sections which are drying, pyrolysis and gasification. The model is based on a combination of models that the Aspen Plus simulator provides, representing the three stages of gasification. Thermodynamics package used in the simulation comprised the Non-Random Two-Liquid (NRTL) model. The model works on the principle of Gibbs free energy minimization and was validated with experimental data of MSW gasification found in the literature. The RYield module was combined with the RGibbs module to describe pyrolysis section, while the RGibbs module was used for the gasification section individually. Proximate and ultimate analysis of RDF pellets and operating conditions used in the model are discussed. The sensitivity analysis module of Aspen Plus was used to research the effect of air equivalence ratio, ER and temperature value on the syngas composition, and carbon conversion. The results indicate that higher temperature improves gasification as the composition of H2 and CO increase, as well as carbon conversion until a temperature of 900 ℃ and higher air equivalence ratio increases the carbon conversion while decreasing syngas quality as there is an increase in CO2 and H2. The most suitable binder for the gasification of RDF derived from MSW is maize starch, with the optimal process parameters for the production of syngas being that of temperature at 780 0C and airflow rate of 6 kg/hr which translates into a fuel-to-air feed ratio of about 1:2. Results obtained are in good agreement with the experimentally measured data in the literature.