Fluidised bed drying is currently receiving much attention as a dewatering option after the beneficiation of fine coal (defined in this study as between 1mm and 2mm particles). The aim of this study was to investigate the removal of moisture from fine coal by using air at relatively low temperatures of between 25°C and 60°C within a controlled environment by lowering of the relative humidity of air. The first part of the experimental work was completed in a controlled climate chamber with the coal samples in a static non-fluidised state. Drying in the second part was carried out using a fluidised bed with conditioned air as the fluidising medium. Introduction of airflow to the system led to a lower moisture content in the coal samples and it also proved to have the ability to increase the drying rate. It was determined that the airflow had the ability to remove more free moisture from the filter cake. In addition more inherent moisture could also be removed by using upward flowing air, resulting in a lower equilibrium moisture content. It was proven that the airflow rate and relative humidity of the drying air contributed to faster drying rates. The effect of temperature was not as significant as expected, but higher temperatures did increase the drying rate at higher airflow and lower humidity conditions. The larger surface areas of particles create surface and capillary forces that prevent the moisture from leaving the finer coal particles. It was found that the rate of drying is independent of the moisture content in the coal sample. Just in terms of the fastest drying time and drying rate in the fluidised bed, it was concluded that the most efficient conditions is airflow above minimum fluidisation point causing vigorous mixing and maximum contact with the drying air. In addition to the high airflow it was concluded that 30% relative humidity and 55°C resulted in the fastest drying time. All the drying processes at all the airflow rates, temperature and relative humidity conditions were energy efficient. This process was shown to be energy positive, resulting in an overall energy gain. The overall energy consumption for the fluidised bed is lower than for all the dryer systems compared to and it compared favourably with other thermal drying technologies. It was therefore shown that this is a viable technology for the dewatering of fine coal. / MIng (Chemical Engineering), North-West University, Potchefstroom Campus, 2014

Deep gold mines use a vast amount of water for various purposes. After use, the water is pumped back to the surface. This process is energy intensive. The control is traditionally done with manual interventions. The purpose of this study is to investigate the effects of automated control on mine dewatering pumps. Automating mine dewatering pumps may hold a great number of benefits for the client. The benefits include electricity cost savings through load shifting, as well as preventative maintenance and pump protection procedures. By automating pumps, the client will benefit from operating more cost effectively and realising electricity cost savings. The equipment needed for pump automation and the procedures involved in the process are discussed as part of this study. A DSM project was implemented in the form of a pump automation project. All safety and quality procedures were followed and training was provided where needed to ensure that personnel understand their duties and responsibilities. This ensures the sustainability of the project after completion. The performance of the project was tested in manual mode, manual scheduled control, manual scheduled surface control and auto control. Manual intervention achieved the highest electricity cost saving of R8.25 million (11.4 MW load shift saving). To achieve this saving the system was exhausted to a point where columns and infrastructure started failing. Auto intervention achieved an electricity cost saving of R5.57 million (7.7 MW load shift savings). The auto intervention achieved a lower electricity cost savings compared to the manual intervention. However, taking all factors into account, such as the damage to infrastructure after a period of manual control, the auto intervention proved the best balance for controlling mine dewatering pumps to achieve savings on the cost of electricity and system sustainability for optimal control. Automated systems can avoid system overload and protect the infrastructure from exhaustion. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2015

Fluidised bed drying is currently receiving much attention as a dewatering option after the beneficiation of fine coal (defined in this study as between 1mm and 2mm particles). The aim of this study was to investigate the removal of moisture from fine coal by using air at relatively low temperatures of between 25°C and 60°C within a controlled environment by lowering of the relative humidity of air. The first part of the experimental work was completed in a controlled climate chamber with the coal samples in a static non-fluidised state. Drying in the second part was carried out using a fluidised bed with conditioned air as the fluidising medium. Introduction of airflow to the system led to a lower moisture content in the coal samples and it also proved to have the ability to increase the drying rate. It was determined that the airflow had the ability to remove more free moisture from the filter cake. In addition more inherent moisture could also be removed by using upward flowing air, resulting in a lower equilibrium moisture content. It was proven that the airflow rate and relative humidity of the drying air contributed to faster drying rates. The effect of temperature was not as significant as expected, but higher temperatures did increase the drying rate at higher airflow and lower humidity conditions. The larger surface areas of particles create surface and capillary forces that prevent the moisture from leaving the finer coal particles. It was found that the rate of drying is independent of the moisture content in the coal sample. Just in terms of the fastest drying time and drying rate in the fluidised bed, it was concluded that the most efficient conditions is airflow above minimum fluidisation point causing vigorous mixing and maximum contact with the drying air. In addition to the high airflow it was concluded that 30% relative humidity and 55°C resulted in the fastest drying time. All the drying processes at all the airflow rates, temperature and relative humidity conditions were energy efficient. This process was shown to be energy positive, resulting in an overall energy gain. The overall energy consumption for the fluidised bed is lower than for all the dryer systems compared to and it compared favourably with other thermal drying technologies. It was therefore shown that this is a viable technology for the dewatering of fine coal. / MIng (Chemical Engineering), North-West University, Potchefstroom Campus, 2014

<p>The present work deals with some aspects of the fluidmechanics of paper-making,more specifically partial dewateringduring roll forming. The study is mainly experimental. Pressureand wire position measurements have been carried out in anexperimental facility, the KTH-Former,which models the rollforming zone of a paper machine.</p><p>Measurements are carried out with pure water for threedifferent wires (fabrics): A non-permeable,a semi-permeable anda conventional wire. Although not used in paper making,thenon-permeable wire is useful when trying to understand thefundamental mechanics of roll forming.The semi-permeable wirewith finite but low permeability is used to model the effectsof the fibre web on the drainage.</p><p>Tests have mainly been carried out for different wiretensions and different jet speeds. It is shown that the localcurvature of the wire is strongly correlated to the dewateringpressure.</p><p>The conventiona wire shows a single pressure peak causingcomplete de- watering in the first part of the dewateringzone.The pressure distributions for the non-and semi-permeablewires are found to show two consecutive pressure peaks followedby a suction peak where the wire is taken of the roll.Thisoscillating behaviour is due to capillary waves where the wiretension plays the role of surface tension on a free surface.Thewavy behaviour of the wire is recovered from an analyticalmodel and the effect is governed by a dimensionless Webernumber. The measured wave lengths correspond well to thosegiven by the theory.</p><p>When the wire tension is high,i.e.a high dewateringpressure,the flow in the impingement region collapses when thedynamic pressure of the headbox jet is about half of thedewatering pressure. It is shown experimentally that the localdrainage shows a correlation to the dewatering pressure andhence to the wire curvature.</p>

Wastewater sludge is considered a valuable source of nutrients and energy. Freeze/thaw treatment is an efficient dewatering method for wastewater sludge management in First Nation communities located in cold climate conditions. Natural freeze/thaw is a simple, practical and low cost method, which can effectively dewater sludge. The objective of this research is to evaluate dewatering, nutrient recovery and organics separation of wastewater sludge originating from different wastewater treatment processes using freeze/thaw processing. The results of experiments showed the effectiveness of this method in sludge dewaterability and solubilisation of organics and nutrients. The sludge solid content increased by approximately 10-fold after treatment. It was effective in solubilisation of about 15.2%, 33.5% and 21.5% of total nitrogen, total phosphorus and total chemical oxygen demand to soluble one, respectively for the non-BNR sludge. However, anaerobic digestion of the solid cake post freeze/thaw treatment did not show enhanced methane yield compared with fresh sludge. / February 2017

Main subject of the diploma thesis is an evaluation of waterworks sludge dewatering using the CST method. The CST or capillary suction time is method developed to evaluate specific resistance to filtration in an indirect way. In principle it is based on the use of filtration paper to measure willingness of sludge to release water or its filterability. Results are measured as time needed for the water to overcome a defined trajectory and expressed in seconds. The shorter the CST time the more filterable is the sludge sample. The CST method has been critically evaluated and it was assessed as a great method for selecting the ideal polymer used for the sludge dewatering and for defining its optimal dose. Measurements have been made on sludge from two waterworks plants Želivka and Kozičín. Polymer products from company Sokoflok and products Praestol and Magnafloc have been tested on both of them. The best polymers for dewatering have been selected. It was Sokoflok 104 for sludge Želivka 1, 55CN for sludge Želivka 2, Magnafloc for sludge Kozičín 1 and 55CN for sludge Kozičín 2. Second subject of the thesis was to evaluate a sludge sensibility to the shear rate. Havlík (2003) and Bache et al.(2003) are describing sludge as a substance very sensitive to higher shear rate which causes that the aggregates...

This master thesis provides an overview of the paper machine with focus on the forming section. The forming section is the first part in the paper machine where the paper pulp is injected through a head box. The paper pulp contains about 99.5% of water and 0.5% fiber. The water as content is reduced by vacuum and gravity. The problem to be studied in this project is related to external rewetting. This is water going back to the paper web from the forming fabric after the dewatering zone. The dewatering is based on vacuum slots under the forming fabric. The vacuum slots absorb water from the soaked paper pulp through the forming fabric. External rewetting causes problem, hence the paper will have a higher dry content when leaving the forming section. The paper should have as low dry content as possible in the end of the forming section. Three different forming fabrics from Albany International were chosen for the project. The structures of the forming fabrics were two different double layers and one plain weave. The performance of the fabrics was studied by 4 different methods. The methods used were 2 different wicking tests, a vacuum dewatering trial and one foulard test. Also micro tomography was done to understand the structure of each design. The main test was a foulard test where the aim was to see in what way the rewetting got affected by different pores sizes. The results showed higher water content for the paper that was on top of the forming fabric with the larger pores.

The purpose of this study was to examine whether any environmental benefits were obtained when the emptying of sludge from septic tanks were carried out with a dewatering technique using polymers compared to complete pump-out. The mean value of transport distance, fuel consumption, CO2 emissions and the weight of waste per septic tank emptying was calculated for each emptying method. For this, data on transport distance, fuel consumption, CO2 emissions per liter of fuel and number of emptied septic tanks were used. An energy audit over a sewage treatment plant was used to calculate the energy consumption for the treatment of the waste from the two emptying techniques. The environmental impact of the use of polymers and the returning of reject water to the septic tank was examined by studying the literature in the research field. The result showed that emptying with a dewatering technique compared to complete pump-out resulted in shorter transports, less fuel consumption, lower CO2 emissions, less waste and a lower energy consumption for waste treatment. The use of polymers in sludge dewatering should not have any adverse effects on aquatic organisms or health impacts if the dosage and the design of the treatment plant is correct. It is not established whether the return of reject water have any environmental effects. In conclusion this report shows that the emptying of septic tanks with a dewatering technique is better than complete pump-out from an environmental point of view.

Typescript (photocopy). / Digitized by Kansas Correctional Industries

Les premiers essais agricoles dans les terres basses de la Guyane française commencent dès 1763 sur les côtes de Kourou. Ce fut le début d’une entreprise qui, sous la forme de dents de scie, va marquer l’économie de cette colonie française de l’Amérique du sud jusqu’à nos jours. Les terres noyées de la Guyane française, sont toutes localisées sur la bande côtière et correspondent à des zones humides (tourbières, mangroves, marais). Au début de la colonisation, en 1604 précisément, les Français se sont établis sur l’île de Cayenne, et ont occupés les terres hautes, situées plus à l’intérieur du continent. L’agriculture de ces terres a débuté à la même période, selon le modèle d’agriculture sur brûlis développé par les autochtones. Ce modèle traditionnel convenait à la production des denrées alimentaires pour des petits groupes. Néanmoins, au bout d’un siècle, leur rendement ne satisfaisait plus au commerce de la colonie. L’épuisement ou la faible productivité de ces terres hautes à la fin du XVIIIeme siècle, a ainsi occasionné une ruée ver les terres basses. Le développement de ces terres noyées avait déjà été entrepris par les Hollandais (Guyane hollandaise), mais ces zones humides rebutaient encore les Colons-Planteurs en Guyane française. Dès l’arrivée de V. Malouet (nouvel intendant de la colonie) vers 1778, les techniques d’assèchement et de construction de polders se développent en Guyane française sous la direction de l’ingénieur J. S. Guisan. Ce dernier essaya de faire des terres noyées, la réponse aux problèmes agricoles de la Guyane française. Mais, les différents évènements socio-politiques qui touchèrent la France à cette époque (Révolution française, abolition de l’esclavage, activités aurifères), mirent fin dès 1848 à cette entreprise. Certaines contraintes climatiques doivent également être considérées. Un siècle plus tard, vers 1950 avec le lancement du plan vert, les rizières de Mana témoignent encore de l’importance de la culture des terres basses en Guyane française. / The first agricultural trials in the lowlands of French Guyana started in AD 1763 on Kourou coasts. It was the beginning of an initiative that will mark the economy of this French colony of South America until today. The flooded lands of French Guyana are all located on the coastal strip. This area is composed of wetlands (peatlands, mangrove and swamps). At the beginning of colonisation, in AD 1604 exactly, French people established themselves on the Cayenne Island and on the uplands (mainland). The cultivation of these uplands started at the same time, adopting the slash-and-burn agriculture developed by autochthonous people. More, this agricultural model was butter suited to foodstuffs production for small groups. However, early in the century, their performance no longer satisfied trade of the colony. Depletion or low production of these uplands at the end of the XVIIIth century, caused a rush to the lowlands. The development of these low lands has already been undertaken by the Dutch (Dutch Guyana), but these wetlands were still rejected by the Colon-planters in the French Guyana. As soon as V. Malouet arrived (new intendant of the colony) ca. AD 1778, the techniques of dewatering and polder construction developed in the French Guyana under the supervision of the engineer J. S. Guisan. He tried to manage the flooded lands as an answer to agricultural problems of the French Guyana. But, several socio-political events occurred in France at this period (the French Revolution, the abolition of slavery, the gold-bearing activity) put a stop to this process in AD 1848. Climate control should also be considered. One century later, around AD 1950, Mana rice fields still testify of the importance of cultivation of lowland of French Guyana, in particular thanks to the launch of the green plan.Keys words: French Guyana