Submitted in fulfillment of the academic requirements for the Masters in Applied Sciences (Chemistry), Durban University of Technology, Durban, South Africa, 2016. / The main aim of this work was to produce levulinic acid (LA) from sugarcane bagasse (SB) and since there is approximately 3 000 000 tons of bagasse produced per annum by 16 factories that are located on the north coast of Kwa-Zulu Natal, after the extraction of sugar. For this project fructose was firstly used for the production of LA, thereafter SB was used to produce LA. Cellulose was extracted from sugarcane bagasse using two types of pre-treatments namely (i) acid-alkali pre-treatment and (ii) liquid hot water (LHW). In the latter method acid hydrolysis and enzymatic hydrolysis was used to hydrolyse cellulose to glucose. For the acid-alkali pre-treatment work, two types of bagasse was used namely (i) mill-run bagasse and (ii) depithed bagasse and for the LHW a mill-run bagasse (pellets form) was used. In both pre-treatment methods the glucose solution was then acid catalysed by two different acids (i) an environment friendly acid, methanesulfonic acid (MSA) and (ii) sulphuric acid, producing levulinic acid. The results showed that MSA and sulphuric acid produced almost the same yield of LA but, MSA is preferred for the production of LA since it is less toxic and less corrosive than sulphuric acid. / M

The sugar refinery process used by Lantic Sugar Ltd generates three by-products having characteristics that give them potential as soil amendments or fertilizers, particularly as a phosphorous and calcium source. Laboratory and a field trials were conducted in order to examine the changes in agronomic properties of soil produced by the application of these residues. / During the laboratory experiment, the by-products examined were spend bone char (SBC), filter-press mud (FPM), clarification scum (SCU) and a compost (COM) produced using FPM and SCU, where as in a field experiment, COM, SBC and a mixture (MIX) made of FPM and SCU, were compared to a commercial fertilizer (TSP) and non-treated soils. / The orthic humic gleysol of clay texture and low pH soil conditions in which the field experiment was conducted resulted in high P fixation of all the applied residues. Contrasts analysis showed that TSP behaved as the soils unamended P for all nutrient concentrations in tissues over two cropping seasons (1993 and 1994), on two crops, namely wheat (Triticum aestivum, L.) and corn (Zea mays, L.). Treatments (residues at different rates of application) did not significantly increase the Ca levels in COM plots nor did they increase the wet aggregate stability of soil under either crop. (Abstract shortened by UMI.)

A compost consisting 95% of the sugar mill byproducts: bagasse, filter press mud, and fly ash, applied at 5 t ha$ sp{-1}$, increased vesicular-arbuscular mycorrhizal infection of sugarcane roots in one of three experimental fields in Barbados. In a plant cane field, compost stimulated formation of intracellular hyphal coils and arbuscules, but not vesicles or hyphae. Infection was greater in roots 35 cm and 65 cm than 5 cm distant from the plant stem, and compost effects were not significant at 5 cm. Two other sources of phosphorus, filter press mud and triple superphosphate, did not affect and suppressed mycorrhizal infection, respectively. Two ratoon crops showed no residual effect of compost on mycorrhizal infection. Compost also stimulated tillering, phosphorus content, and perhaps yield of cane, but did not differentially effect high versus low tillering or sloped versus flat areas. Root length, weight, and specific root length were unaffected by compost addition, but root branching was decreased.

Crystallization is done in the sugar industry using natural circulation vacuum evaporative crystallizers known as vacuum pans. the fluid which is known as massecuite consists of a suspension of crystals in concentrated molasses. It is highly viscous and slightly non-Newtonian, and laminar conditions prevail in the apparatus. Research on forced convection boiling heat transfer, pressure drop and vapour holdup has been done mostly in turbulent flow under pressures higher than atmospheric, but no studies have been made when boiling viscous fluids under vacuum. This thesis describes a series of experiments which were undertaken with the following objectives: (a) to determine the influence of the pertinent variables on heat transfer, friction losses and vapour holdup while boiling under laminar conditions (b) to produce a method for the calculation of the evaporation and circulation rates in vacuum pans, as this would make possible the optimization of this type of equipment. The apparatus used consisted of a single tube steam heated forced circulation evaporator. The void fraction, pressure and centerline temperature were measured along the tube. The fluids used were syrup, molasses and massecuite covering a thousandfold change in viscosity. The tests were conducted under different conditions of vacuum and steam pressures with varying tube inlet velocities. The experimental results show that the boiling heat transfer coefficient can be correlated as a function of the two phase Reynolds number and dimensionless density ratio and that it is inversely proportional to the tube length to the power of one third. The pressure drop can be estimated using the equation of Oliver and Wright (1964) for bubbly flow. Equations are proposed for calculating the void fraction in the highly subcooled region and point of bubble departure. These equations form the basis of a computer program which by a stepwise and iterative method simulates the boiling process along the tube. Measurements taken on a natural circulation pan with tubes of different length show that this method predicts the effect of the tube length with reasonable accuracy. The limitations of this study are that the experiments were done with a single diameter tube so that the effect of diameter has not been established with certainty. Only sugar products were used in the experiments, and caution is necessary if this method is applied to other fluids. / Thesis (Ph.D.)-University of Natal, Durban, 1985.

In the current era, oil deficit countries around the world seriously consider shifting dependence from conventional gasoline to renewable bio-ethanol fuel in the transport industry. Arguably, blending l0vol% dry ethanol with 90vol% unleaded gasoline enables ethanol fuel to penetrate the fuel market at relatively lower development costs. Despite creating an important market for the ethanol industry, fuels containing dry ethanol of differential proportions multiply the local risks associated with fuel combustion. Making a sale of one drop of ethanol fuel, for example, is intrinsically tied to the sale of more drops of imported gasoline. Furthermore, an increase (decrease) in conventional fuel prices directly influences a decline (increase) in daily sales of ethanol fuel. Blending bio-ethanol fuel with conventional gasoline in various proportions fails to address the multifaceted fossil fuel crisis in oil deficit countries. Although reducing bio-ethanol production costs can buffer fuel prices to a significant degree when blended in higher ratios, industrial competition for bio-feedstock is a serious limitation for bio-ethanol development in all parts of the globe. Nevertheless, advances in biotechnology may allow the use of a wide range of cheaper ethanol feedstocks (e.g. lignocellulose) leading to an important reduction in ethanol production costs. Temporal and spatial variability of lignocellulosic ethanol potentials in the sugar industry is investigated over southern Africa as a whole. The influence of extremely low (high) production of sugar cane on the potentials development of lignocellulosic ethanol plants is demonstrated in this work. Characterization of bioethanol fuel markets on the basis of blending with gasoline is undertaken at the subcontinental scale. The connectivity between development, consumption per capita, population growth, bio-ethanol energy demand, as well as the critical limits of land stock potentials is examined in this study. On the basis of the special influence that each of the processes indicated above have on bio-ethanol fuel development, an integrated approach toward optimizing the total value of bio-ethanol fuel in the region is formulated. This approach allows the investigation to determine whether critical and beyond critical conditions of land stock lead to a collapse of a human consumption type or whether bio-ethanol fuel development is a totally viable process. Finally, this work ascertains whether sustainable biofuel development is an oxymoron because human development demands a constantly growing fuel consumption per capita, or because of increasing the lower limit, with an infinite upper limit for human development, or as a product of the combined effects of increasing human population with a higher consumption rate per capita of non-growing and non-developing land stock units. / Thesis (Ph.D.)-University of KwaZulu Natal, Durban, 2004.

The South African sugar industry generates excessive amounts of sugar cane bagasse (~ 25 wt% of feed) as a byproduct during the extraction of sugar juice from cane. Although bagasse is extensively consumed in various processes, a substantial amount remains unexploited. The industry's core business is the production of refined sugar which involves among others, a step of decolourising raw sugar liquor. Activated carbons are well known adsorbents and their excellent decolourisation capabilities have been established since 1800 in the sugar industry. The possibility of making suitable in-house activated carbons from sugar cane bagasse to aid the decolourisation process of raw sugar liquor is of interest to the growing South African sugar industry. The purposes of this research study were to develop an understanding on the manufacture of activated carbons from sugar cane bagasse, produce suitable activated carbons on a laboratory scale, characterize them and subsequently determine their sugar decolourisation capabilities under simulated conditions. The application of the two-step physical method of processing was found to be the most effective and feasible route to produce activated carbons from sugar cane bagasse for the purposes of decolorizing unrefined sugar. A semi-batch process was developed whereby compressed sugar cane bagasse was pyrolysed under a nitrogen atmosphere at a heating rate of 10 °C/min to the final pyrolysis temperature for a desired hold time resulting in bagasse chars with a rudimentary pore structure. These bagasse chars were subsequently subjected to partial and controlled gasification with a steam/nitrogen mixture at higher temperatures to produce the final activated carbon product. Both pyrolysis and activation were carried out in a pyrolysis furnace that was modified to represent a fixed bed reactor system. The process was designed such that it included a steam supply and a gas cleaning system. Feasible processing conditions were established by varymg the temperature, hold time and partial pressure of steam in the pyrolysis furnace. The bagasse chars and final activated carbons were characterized with respect to surface area, pore volume, pore size distribution, methylene blue number, iodine number and molasses number. The optimum pyrolysis conditions were found to be at heating rate of 10°C/min to the final pyrolysis temperature of 680 °C for a hold time of 1 hour, which gave rise to microporous carbons. Increasing the steam partial pressure and activation temperature during activation of bagasse chars resulted in the gasification reaction proceeding at a much faster rate leading to well developed mesoporous activated carbons having high adsorption capacity for large colour bodies present in molasses and sugar liquor. This was achieved by activating bagasse chars at a temperature of 900°C for 2 hours with a steam / nitrogen mixture of 1:0.6 which resulted in 50% bum-off being reached. Excellent powder and granular activated carbons were produced from sugar cane bagasse fibres by the established process with the latter being mixed with refined sugar prior to pyrolysis and activating for half an hour extra. A typical final activated carbon produced in this research possessed a BET surface area of 995 m2/g, pore volume of 0.82 crrr'zg, iodine number of 994 mg/g, molasses number of 700 and methylene blue number of 256 mg/g. High ash content in the bagasse raw material tends to decrease the surface area and pore volume for adsorption of the final activated carbon. Both granular and low ash bagasse activated carbons possess high adsorption capacity to remove large colour bodies from molasses and brown liquor solutions and compare well with commercial Norit N2 carbon . Approximately 80% colour removal was achieved using 0.5 g carboni 100g brown liquor. The bagasse activated carbons were stable in acidic and basic brown liquor solution and maintained their high decolourisation potential. The ability of bagasse activated to replace commercial activated carbons has been proven in this study. The option of producing both granular and powder activated carbons provide flexibility of the sugar industry to choose between batch and continuous adsorption systems during sugar decolourisation. This research has established that the fact that excellent sugar decolourising activated carbons can be produced from South African sugar cane bagasse fibres. However, more research needs to be carried out in order for the sugar industry to take this project to the commercial stage and it is suggested that a pilot study and an economic study be carried out. / Thesis (M.Sc.)-University of Natal, Durban, 2003.

The purpose of clarification in the sugar industry is to remove soluble, insoluble and colloidal matter from cane juice. Efficient clarification is required to produce high quality sugar and to prevent entrainment of solids in downstream equipment. The objective of this study is to produce a Computational Fluid Dynamics (CFD) model of the Magra Ultrasep clarifier. This was accomplished by: • Modelling the hydrodynamics of a laboratory scale clarifier In the Fluent CFD program. • Incorporating the flocculation process into the CFD model. • Performing experiments on a pilot scale clarifier to obtain parameter values for the flocculation model. The hydrodynamic model of the clarifier showed the presence of a recirculation zone above the baffle plate. Particle injections using Fluent's discrete phase modelling option determined that particles within the size range of IOOj..Lm to 4mm would circulate in this region, forming the bed of floc particles required for the Magra Ultrasep to work efficiently. The flocculation process in Fluent was represented using three different solid phases of different particle sizes. Small and medium sized particles were allowed to combine to form larger particles by changing the volume fractions according to three rate equations. A fibre glass laboratory scale model was set up at Maidstone Sugar Mill and fed the same sugar cane juice that enters the Rapi-Dorr clarifiers. The experimental results were then fed into a simplified flocculation model in MATLAB. An overall rate constant (k) of 5kg.m-3.s-) for the flocculation kinetic equation satisfied the experimental result. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2008.

This dissertation focuses on the application of tomography in the sugar milling process, specifically within the vacuum pan. The research aims to improve the efficiency and throughput of a sugar mill by producing real-time images of the boiling dynamic in the pan and hence can be used as a diagnostic tool. The real-time tomography system is a combination of ruggedized data collecting hardware, a switching circuit and software algorithms. The system described in this dissertation uses 16 electrodes and estimates images based on the distinct differences in conductivities to be found in the vacuum pan, i.e. a conductive syrup-like fluid (massecuite) and bubbles. There is a direct correlation between the bubbles produced during the boiling process and heat transfer in the pan. From this correlation one can determine how well the pan is operating. The system has been developed in order to monitor specific parts of a pan for optimal boiling. A binary reconstructed image identifies either massecuite or water vapour. Each image is reconstructed using a modified neighbourhood data collection method and a back projection algorithm. The data collection and image reconstruction take place simultaneously, making it possible to generate images in real-time. Each image frame is reconstructed at approximately 1.1 frames per second. Most of the system was developed in LabVIEW, with some added external drive electronics, and functions seamlessly. The tomography system is LAN enabled hence measurements are initiated through a remote PC on the same network and the reconstructed images are streamed to the user. The laboratory results demonstrate that it is possible to generate tomographic images from bubbles vs massecuite, tap water and deionized water in real-time. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2012.

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