An extensive study has been made of the factors affecting sample dispersion in flow injection analysis. This has included the effect of different manifold parameters on peak height and shape, and the use of various flow models to describe the physical processes involved. The factors investigated included sample flow-rate, tube length and diameter, sample volume, and the diffusion coefficient of the solute. The role of the detector has also been investigated, and was found to exert a strong influence on the observed dispersion behaviour of a flow injection manifold. In the light of this, a low volume flow cell was constructed which minimised the contribution of the detector to dispersion. Different modes of sample injection ("time" and "slug" injection) have been studied, and an automatic valve constructed in connection with the work. Both new and existing flow models have been evaluated in terms of their ease-of-use and ability to predict peak shape. Conditions for which the different models were valid were derived both experimentally and from consideration of the assumptions of the models. The applications of such models to the characterisation and design of flow manifolds has also been considered, and this approach compared to the purely theoretical and empirical approaches that have been described in the literature. The models examined in this thesis are the convection, diffusion, tanks-in-series, well-stirred tank, two-tanks in- parallel and two-tanks-in-series models. Finally, the practical implications of this work for the design of flow injection manifolds and the derivation of so-called "rules for dispersion" have been discussed, and suggestions made for further areas of research.

This thesis examines the bioleaching of six different Canadian nickel sulphide ores at pH levels above what is generally considered optimum (~ 2). The majority of work discussed in this thesis was conducted with a low-grade metamorphosed ultramafic nickel sulphide ore from Manitoba, Canada (Ore 3), which is not currently exploitable with conventional technologies. The ore contains 21% magnesium and 0.3% nickel. Nickel is the only significant metal value, and is present primarily as pentlandite. A substantial fraction of the magnesium is present as the serpentine mineral lizardite, making processing difficult with conventional pyro- and biohydrometallurgical techniques. The work with this ore has two equally important objectives: to minimize magnesium mobilization and to obtain an acceptable level of nickel extraction. Batch stirred-tank bioleaching experiments were conducted with finely ground ore ( 147 µm) with temperature and pH control. The first phase of experimentation examined the effect of pH (2 to 6) at 30 °C, and the second phase examined all combinations of three pH levels (3, 4 and 5) and five temperatures (5, 15, 22.5, 30, and 45 °C).

This thesis examines the bioleaching of six different Canadian nickel sulphide ores at pH levels above what is generally considered optimum (~ 2). The majority of work discussed in this thesis was conducted with a low-grade metamorphosed ultramafic nickel sulphide ore from Manitoba, Canada (Ore 3), which is not currently exploitable with conventional technologies. The ore contains 21% magnesium and 0.3% nickel. Nickel is the only significant metal value, and is present primarily as pentlandite. A substantial fraction of the magnesium is present as the serpentine mineral lizardite, making processing difficult with conventional pyro- and biohydrometallurgical techniques. The work with this ore has two equally important objectives: to minimize magnesium mobilization and to obtain an acceptable level of nickel extraction. Batch stirred-tank bioleaching experiments were conducted with finely ground ore ( 147 µm) with temperature and pH control. The first phase of experimentation examined the effect of pH (2 to 6) at 30 °C, and the second phase examined all combinations of three pH levels (3, 4 and 5) and five temperatures (5, 15, 22.5, 30, and 45 °C).

Human mesenchymal stem cells (hMSCs) are a promising candidate for cell-based therapies given their therapeutic potential and propensity to grow in vitro. However, to generate the cell numbers required for such applications, robust, reproducible and scalable manufacturing methods need to be developed. To address this challenge, the expansion of hMSCs in a microcarrier-based bioreactor system was investigated. Initial studies performed in T-flask monolayer cultures investigated the effect of key bioprocess parameters such as dissolved oxygen concentration (dO2), the level of medium exchange and the use of serum-free media. 20 % dO2 adversely impacted cell proliferation in comparison to 100 % dO2, whilst FBS-supplemented DMEM was found to be the most consistent and cost-effective cell culture medium despite the advances in serum-free cell culture media. Several microcarriers were screened in 100 mL agitated spinner flasks where Plastic P102-L was selected as the optimal microcarrier for hMSC expansion given the high cell yields obtained, its xeno-free composition and effective harvest capacity. The findings from the initial small-scale studies culminated in the successful expansion of hMSCs on Plastic P102-L microcarriers in a fully equipped 5 L stirred-tank bioreactor (2.5 L working volume), the largest reported volume for hMSC microcarrier culture to date. A maximum cell density of 1.68 x 105 cells/mL was obtained after 9 days in culture; further growth was limited by the low glucose concentration and lack of available surface area. A novel, scalable harvesting method was also developed, allowing for the successful recovery of hMSCs. Importantly, harvested hMSCs retained their immunophenotype, multipotency and ability to proliferate on tissue culture plastic.

This thesis examines the bioleaching of six different Canadian nickel sulphide ores at pH levels above what is generally considered optimum (~ 2). The majority of work discussed in this thesis was conducted with a low-grade metamorphosed ultramafic nickel sulphide ore from Manitoba, Canada (Ore 3), which is not currently exploitable with conventional technologies. The ore contains 21% magnesium and 0.3% nickel. Nickel is the only significant metal value, and is present primarily as pentlandite. A substantial fraction of the magnesium is present as the serpentine mineral lizardite, making processing difficult with conventional pyro- and biohydrometallurgical techniques. The work with this ore has two equally important objectives: to minimize magnesium mobilization and to obtain an acceptable level of nickel extraction. Batch stirred-tank bioleaching experiments were conducted with finely ground ore ( 147 µm) with temperature and pH control. The first phase of experimentation examined the effect of pH (2 to 6) at 30 °C, and the second phase examined all combinations of three pH levels (3, 4 and 5) and five temperatures (5, 15, 22.5, 30, and 45 °C).

A theoretical study on the hydrodynamics of mixing processes in stirred tanks is described. The primary objective of this study is to investigate flow field and power consumption generated by the six blades Rushton turbine impeller in baffled, flat-bottom cylindrical tank both at laminar and turbulent flow regime both qualitatively and quantitatively. Experimental techniques are expensive and time consuming in characterizing mixing processes. For these reasons, computational fluid dynamics (CFD) has been considered as an alternative method. In this study, the velocity field and power requirement are obtained using FASTEST, which is a CFD package. It employs a fully conservative second order finite volume method for the solution of Navier-Stokes equations. The inherently time-dependent geometry of stirred vessel is simulated by a multiple frame of reference approach. The flow field obtained numerically agrees well with those published experimental measurements. It is shown that Rushton turbine impeller creates predominantly radial jet flow pattern and produces two main recirculation flows one above and the other below the impeller plane. Throughout the tank impeller plane dimensionless radial velocity is not affected significantly by the increasing impeller speed and almost decreases linearly with increase in radial distance. Effect of the baffling on the radial and tangential velocities is also investigated. It is seen that tangential velocity is larger than radial velocity at the same radial position in unbaffled system. An overall impeller performance characteristic like power number is also found to be in agreement with the published experimental data. Also power number is mainly affected by the baffle length and increase with increase in baffle length. It is concluded that multiple frame of reference approach is suitable for the prediction of flow pattern and power number in stirred tank.

Thesis (DTech (Electrical Engineering))--Cape Peninsula University of Technology, 2016. / Majority of the industrial systems encountered are significantly non-linear in nature, so if they are synthesised and designed by linear methods, then some of salient features characterising of their performance may not be captured. Therefore designing a control system that captures the nonlinearities is important. This research focuses on the control design strategies for the Continuous Stirred Tank Reactor (CSTR) process. To control such a process a careful design strategy is required because of the nonlinearities, loop interaction and the potentially unstable dynamics characterizing the system. In these systems, linear control methods alone may not perform satisfactorily. Three different control design strategies (Dynamic decoupling, Decentralized and Input-output feedback linearization controller) are proposed and implemented .in the Matlab/Simulink platform and the developed strategies are then deployed to the design of distributed automation control system configuration using the IEC 61499 standard based functional block programming language. Twin CAT 3.1 system real-time and Matlab/Simulink (www.mathworks.com) environment are used to test the effectiveness of the models The simulation results from the investigation done between Simulink and TwinCAT 3 software (Beckhoff Automation) platforms in the case of the model transformation and closed loop simulation of the process for the considered cases have shown the suitability and the potentials of merging the Matlab/Simulink control function blocks into the TwinCAT 3.1 function blocks in real-time. The merits derived from such integration imply that the existing software and software components can be re-used. This is in line with one of the IEC 6144 standard requirements such as portability and interoperability. Similarly, the simplification of programming applications is greatly achieved. The investigation has also shown that the integration the of Matlab/Simulink models running in the TwinCAT 3.1 PLC do not need any modification, hence confirming that the TwinCAT 3.1 development platform can be used for the design and implementation of controllers from different platforms. Also, based on the steps required for model transformation the between the Matlab/Simulink to the TwinCAT 3 functional blocks, the algorithms of the control design methodologies developed, simulation results are used to verify the suitability of the controls to find whether the effective set-point tracking control and disturbance effect minimisation for the output variables can be achieved in real-time using the transformed Simulink blocks to the TwinCAT 3 functional blocks, then downloaded to the Beckhoff CX5020 PLC for real-time execution. Good set-point tracking control is achieved for the MIMO closed loop nonlinear CSTR process for the considered cases of the developed control methodologies. Similarly, the effects of disturbances are investigated. TwinCAT functional modules achieved good set-point tracking with these disturbances minimization under all the cases considered.

Research into hydrate production technologies has increased in the past years. While many technologies have been presented, there is no consensus on which reactor design is best for each potential application. A direct experimental comparison of hydrate production technologies has been carried out in between a variety of reactor configurations at similar driving force conditions. Three main reactor types were used: a stirred tank, a fixed bed and a bubble column and compared different phase contacting patterns for the stirred tank and bubble column. In the initial phase of hydrate formation in a stirred tank, formation was mass and heat transfer limited at the lower stirring speed, and heat transfer limited at the higher stirring speed. After more than 10% of the water had been converted to hydrate, formation was mass transfer limited regardless of the other conditions. Neither the use of a gas inducing impeller, nor a 10 wt% particle slurry significantly affected hydrate formation rates; however, the particle slurry did lower the induction time. Due to the poor scale-up of impeller power consumption in a stirred tank, a semi-batch fixed bed was studied since it does not require any power input for mixing. The significantly slower rates of formation observed in the semi-batch fixed bed, as well as the lost reactor capacity to particles, mean that this type of system would require a much larger reactor. Faster volume and power normalized rates of hydrate formation were observed in the bubble column than in a stirred tank at similar mass transfer driving force conditions. Higher conversions of water to hydrate were observed in the bubble column because mixing was accomplished by bubbling gas from the bottom rather than by an impeller. The highest conversions of water and gas were achieved during a later stage of accelerated hydrate formation, indicating an optimal hydrate fraction for continuously operated bubble column reactors. The second stage of hydrate formation occurred more frequently at higher gas flowratess. Therefore, the increased water conversion and single-pass gas conversion justify the increased energy input required by the higher gas flowrate. Balancing the rates of mass transfer and heat removal was also critical for optimal bubble column as insufficient mass transfer would result in a lower rate of formation and insufficient heat transfer would cause previously formed hydrates to dissociate. The addition of 10wt% glass beads to the reactor promoted hydrate formation; however, it did not do so sufficiently to make up for the loss in reactor capacity or the increased energy requirement.

Enzymes, as nature’s catalysts, show remarkable abilities that can revolutionize the chemical, biotechnological, bioremediation, agricultural and pharmaceutical industries. However, the narrow range of stability of the majority of described biocatalysts limits their use for many applications. To overcome these restrictions, extremozymes derived from microorganisms thriving under harsh conditions can be used. Extremophiles living in high salinity are especially interesting as they operate at low water activity, which is similar to conditions used in standard chemical applications. Because only about 0.1 % of all microorganisms can be cultured, the traditional way of culture-based enzyme function determination needs to be overcome. The rise of high-throughput next-generation-sequencing technologies allows for deep insight into nature’s variety. Single amplified genomes (SAGs) specifically allow for whole genome assemblies from small sample volumes with low cell yields, as are typical for extreme environments. Although these technologies have been available for years, the expected boost in biotechnology has held off. One of the main reasons is the lack of reliable functional annotation of the genomic data, which is caused by the low amount (0.15 %) of experimentally described genes. Here, we present a novel annotation algorithm, designed to annotate the enzymatic function of genomes from microorganisms with low homologies to described microorganisms. The algorithm was established on SAGs from the extreme environment of selected hypersaline Red Sea brine pools with 4.3 M salinity and temperatures up to 68°C. Additionally, a novel consensus pattern for the identification of γ-carbonic anhydrases was created and applied in the algorithm. To verify the annotation, selected genes were expressed in the hypersaline expression system Halobacterium salinarum. This expression system was established and optimized in a continuously stirred tank reactor, leading to substantially increased cell amounts and protein yields. The resulting gene expression products were assessed for function in vivo and/or in vitro. Our functional evaluation of the tested genes confirmed our annotation algorithm. Our developed strategy offers a general guide for using SAGs as a source of scientific and industrial investigations into “microbial dark matter” and may help to develop new catalysts, applicable for novel reactions in green chemistry.

The global demand for food is increasing. Different nutrients are used to increase growth in agriculture and are thus essential for the world ́s food supply. An important and common nutrient is phosphorus. It can be mined, in the form of phosphate, from phosphate rock. The problem is that mining causes environmental problems and phosphate rock is a non-renewable resource. A risk is that phosphorus will become a scarce commodity in about 100 years.  Sewage sludge from wastewater treatment plants (WWTP) is rich in phosphorus. In Sweden and other European countries, a stricter legislation is expected with consideration of an increased recovery of phosphorus from sewage sludge. A ban on the spread of hazardous substances like drug residues and heavy metals from the sludge is also expected. Incineration of the sludge can be done to eliminate hazardous substances and at the same time recover phosphorus and metals. Development of technologies to recover phosphorus from incinerated sewage sludge is therefore topical.  EasyMining is a company that invents new technologies to close nutrient cycles. One of their present projects is about recycling phosphorus, iron, and aluminium from incinerated sewage sludge. Hydrochloric acid (HCl) is used to leach the ash and in the following steps metals and phosphorus are recovered, and heavy metals are removed. Batch experiments have been performed and EasyMining examines the process in a continuous stirred tank reactor (CSTR).  The aim with this project is to compare the batch and continuous process for the ash leaching step. The study was limited to investigate different residence times and liquid to solid ratios (L/S ratios) for the ash leaching step in the CSTR. To accomplish the aim, mainly experimental studies have been performed. A total of 14 runs have been conducted to investigate the continuous process. The residence times 10, 30 and 60 min and the L/S ratios 2.5, 3 and 3.5 ml/g were evaluated. The lab-set up consisted of a peristaltic pump to pump diluted HCl solution, a conveyor belt to dose the ash and a CSTR. The filtrate was analysed for phosphorus, iron, and aluminium with a spectrophotometer. Interpretation of the result was conducted after each run and the data was then compared to previous batch data from within the company. A paired t-test was used to evaluate if there was a significant difference in the mean values between different residence times and L/S ratios.  The result shows that the leching is very fast and longer residence times or higher L/S ratios do not result in higher yields for phosphorus, iron, or aluminium. There is no significant difference between the examined residence times or L/S ratios in the paired t-test. Data from the batch process shows that the investigated residence times and L/S ratios do not affect the yield. A more even distribution of the yields is obtained in the batch process compared to the continuous process. The less even distribution in the continuous process, probably depends on errors in the method and the equipment used in the process. For example, there were some problems with the ash dosing, which led to an inconstant L/S ratio in the runs. This affected the calculated yields significantly. Overall, the batch process results in slightly higher yields. This is especially the case when excluding high calculated yields in the continuous process, probably obtained because of an overdosing of the ash. / Den globala efterfrågan på mat ökar. Olika näringsämnen används för att få en högre tillväxt i jordbruket och dessa är essentiella för världens livsmedelsproduktion. Ett viktigt och vanligt näringsämne är fosfor och det bryts i form av fosfat från fosfatmineral. Problemet är att brytningen förorenar miljön och dessutom är fosfat-sten en icke förnyelsebar resurs. Det finns en risk att fosfor blir en bristvara om cirka 100 år.  Avloppsslam från vattenreningsverk innehåller höga fosfatkoncentrationer. I Sverige samt i andra europeiska länder förväntas en striktare lagstiftning, som kräver en ökad återvinningsgrad av fosfor från avloppsslam. Även ett förbud mot spridningen av giftiga substanser som läkemedelsrester och tungmetaller förväntas införas. Slammet kan förbrännas för att eliminera farliga substanser samtidigt som fosfor och olika metaller kan återvinnas. Utvecklingen av nya tekniker för återvinning av fosfor från bränt avloppsslam är därför väldigt aktuell.  EasyMining är ett innovationsföretag som utvecklar nya tekniker för att erhålla slutna näringskretslopp. Ett av deras pågående projekt handlar om att återvinna fosfor, aluminium och järn från förbränt avloppsslam. Saltsyra används för att laka askan och i nästkommande steg återvinns fosfor och metaller, samtidigt som tungmetaller separeras. Satsvisa försök har genomförts och EasyMining vill nu undersöka processen i en tankreaktor.  Syftet med projektet är att jämföra resultat från den satsvisa driften med resultat från en kontinuerlig process för ask-lakningssteget. Studien begränsades till att endast undersöka olika uppehållstider och förhållandet mellan vätskan och askan (L/S-förhållande) i lakningssteget. För att uppnå syftet genomfördes huvudsakligen experimentella studier. 14 körningar genomfördes totalt för undersökning av den kontinuerliga processen. Undersökta uppehållstider var 10, 30 och 60 min och undersökta L/S-förhållandena var 2,5, 3 och 3,5 ml/g. Laborationsuppställningen bestod av en peristaltisk pump för tillförsel av utspädd saltsyralösning, ett rullband för dosering av askan samt en tankreaktor. Filtratet analyserades för fosfor, järn och aluminium i en spektrofotometer. Efter varje körning tolkades resultatet och jämfördes därefter med data från de av företaget tidigare utförda satsvisa försöken. Ett parat t-test användes för att utvärdera om det fanns någon signifikant skillnad i medelvärden mellan olika uppehållstider och L/S-förhållanden.  Resultatet visar att lakningen är väldigt snabb och längre uppehållstider eller högre L/S-förhållanden ger inte högre utbyten för fosfor, järn eller aluminium. Ingen signifikant skillnad erhålls mellan undersökta uppehållstider eller L/S-förhållanden i de parade t-testen. Data från de satsvisa försöken visar att de undersökta uppehållstiderna och L/S-förhållandena inte påverkar utbytet. En mindre spridning av utbyten erhålls i den satsvisa driften jämfört med den kontinuerliga. Den större spridningen i den kontinuerliga processen beror förmodligen på felkällor i processens metod/utrustning. Exempelvis var det en del problem med askdoseringen, vilket medförde icke konstanta L/S-förhållanden. Detta påverkade det beräknade utbytet signifikant. Generellt erhålls något högre utbyten i den satsvisa processen. Framförallt då höga beräknade utbyten exkluderas i den kontinuerliga processen på grund av en överdosering av askan.