published_or_final_version / Mechanical Engineering / Master / Master of Philosophy

Desalination of seawater is a widely used technology throughout the world, but is not commonly used in South Africa for domestic water supply. The reasons for this are varied, but very often are based on the assumption that desalination is extremely costly in relation to more traditional water supplies. An economic analysis is undertaken comparing the cost of supplying water to the coastal town of Zinkwazi from various sources including desalination using reverse osmosis. Zinkwazi has an existing borehole water supply that is insufficient to meet current and future demands. The town is also remote from regional bulk surface water infrastructure, which makes it suitable for the investigation of an alternative stand-alone water supply such as desalination. Solving the water supply problems at Zinkwazi is important to Umgeni Water and would support two broad strategic goals of the organisation. Zinkwazi falls within the Ilembe District Municipality, which is an important stakeholder within Umgeni Water's area of jurisdiction. Improving the water supply situation at Zinkwazi is in line with Umgeni Water's goal of assisting Municipalities to meet their developmental objectives. Using desalination to meet this objective is in line with Umgeni Water's goal of using innovative products to alleviate problems of existing customers. Desalination is a multi-billion dollar industry that is growing as traditional surface and goundwater resources become fully utilized and more polluted. Desalination potentially represents a growth opportunity that Umgeni Water, with its expertise in water treatment and supply, could pursue in Africa and Southern Africa in particular. The investigation found that desalination is the most affordable method of supplying water to the town of Zinkwazi and the construction of a desalination pilot plant is recommended for further investigation. / Thesis (MBA)-University of KwaZulu-Natal, Pietermaritzburg, 2005.

Renewable power generation from the controlled mixing of sea and fresh water is relatively unexplored when compared to the development for solar, wind, and other sustainable power alternatives. When global river discharge was taken into account, an estimated 2.6 TW of obtainable energy exists in untapped salinity gradients. Reverse electrodialysis is one proposed power-generating mechanism for harnessing energy from brackish environments and relies on the transport of aqueous salt ions through an apparatus of ion-exchange membranes. In this thesis, operational parameters, including flow direction, salinity composition, and membrane selectivity, are investigated. For optimal performance, I have employed counter-current flow mode with monovalent ion selective membranes and pure 0.5 M NaCl saline solution. The results show that a maximum open circuit voltage (OCV) level of 2.01 V is obtained with an active membrane area of 0.0756 m². The presence of multivalent ions in the feed solutions hinders OCV levels, but the effects are reduced with monovalent-selective membranes. Preliminary results are insightful; in order to increase the commercially viability of this technology, future work is needed to enhance the performance properties of the ion exchange membranes.

Water injection has been practiced to displace the hydrocarbons towards adjacent wells and to support the reservoir pressure at or above the bubble point. Recently, waterflooding in sandstone reservoirs, as secondary and tertiary modes, proved to decrease the residual oil saturation. In calcareous rocks, water from various resources (deep formation, seawater, shallow beds, lakes and rivers) is generally injected in different oil fields. The ions interactions between water molecules, salts ions, oil components, and carbonate minerals are still ambiguous. Various substances are usually added before or during water injection to enhance oil recovery such as dilute surfactant. Various methods were used including surface charge (zeta potential), static and dynamic contact angle, core flooding, inductively coupled plasma spectrometry, CAT scan, and geochemical simulation. Limestone and dolomite particles were prepared at different wettability conditions to mimic the actual carbonate reservoirs. In addition to seawater and dilute seawater (50, 20, 10, and 1 vol%), formation brine, shallow aquifer water, deionized water and different crude oil samples were used throughout this study. The crude oil/water/carbonates interactions were also investigated using short and long (50 cm) limestone and dolomite rocks at different wettability and temperature conditions. The aqueous ion interactions were extensively monitored via measuring their concentrations using advanced analytical techniques. The activity of the free ions, complexes, and ion pairs in aqueous solutions were simulated at high temperatures and pressures using OLI electrolyte simulation software. Dilute seawater decreased the residual oil saturation in some of the coreflood tests. Hydration and dehydration processes through decreasing and increasing salinity showed no impact on calcite wettability. Effect of individual ions (Ca, Mg, and Na) and dilute seawater injection on oil recovery was insignificant in compare to the dilute surfactant solutions (0.1 wt%). The reaction mechanisms were confirmed to be adsorption of hydroxide ions, complexes and ion pairs at the interface which subsequently altered the surface potential from positive to negative. Results in this study indicate multistage waterflooding can enhance oil recovery in the field under certain conditions. Mixed streams simulation results suggest unexpected ions interactions (NaCO3-1, HSO4-1, NaSO4-1 and SO4-2) with various activities trends especially at high temperatures.

Abstract available in PDF copy. / Thesis (M.Sc.-Chemical Engineering)-University of Natal, 1988.

Most common inorganic foulants in RO processes operating on brackish water are calcium carbonate, calcium sulphate and silica. However, silica fouling is the recovery limiting factor in RO system. Silica chemistry is complex and its degree of fouling strongly depends on the silica solubility and its polymerization under different operating conditions of RO process. In several studies carried out in batch and dynamic tests, the presence of polyvalent cations and supersaturation of silica in solutions were found to be the important factors (apart from pH and temperature) that affected the rate of silica polymerization and its induction period. Agitation did increased silica solubility; however, its effect was negligible in presence of polyvalent cations. Alkalization of water solution by coagulants particularly sodium hydroxide was found suitable for silica removal during pretreatment. The presence of magnesium in solution played a key role in silica removal mostly by the mechanism of adsorption to the metal hydroxide. The options of inline mixing (high agitation) for 5 to 10 minutes and microfiltration before RO were found suitable for silica pretreatment. During dynamic tests, the most dominant mechanism for salt deposition (mostly CaSO4) was particulate type in high concentration water solution; while crystallization fouling was the prevailing mechanism of deposition (mostly CaCO3 and silica) in low concentration solution. Silica showed significant effect on size and shape of inorganic salt crystals during coprecipitation. Moreover, the presence of common antiscalants promoted silica fouling. This important finding recommends an extra caution while using antiscalants in case feed water contains silica to a level that can attain saturation near membrane during RO process. A model was developed to predict the silica fouling index (SFI) based on the experimental data for induction period of silica polymerization. The model takes into account the effect of polyvalent cations and concentration polarization near membrane during RO process. It provides a conservative basis for predicting the maximum silica deposition in RO process at the normal operating conditions. A generalised correlation, which was developed for determination of the mass transfer coefficient in RO process, incorporated the effect of temperature change that is usually not considered in previous correlations. A correlation for reduction of silica content in feed water, down to a safe limit of 15 ppm for RO process, was also formulated and validated by the experimental results.

Diss. (sammanfattning). Uppsala : Sveriges lantbruksuniv., 2003. / Härtill 6 uppsatser.

SILVA, Francisco Leandro Barbosa da. Respostas de plantas de feijão-de-corda à aplicação de biofertilizantes via foliar, sob condições de baixa e alta salinidade. 2011. 63 f. Dissertação (Mestrado em engenharia agrícola)- Universidade Federal do Ceará, Fortaleza-CE, 2011. / Submitted by Elineudson Ribeiro (elineudsonr@gmail.com) on 2016-06-23T17:29:01Z No. of bitstreams: 1 2011_dis_flbsilva.pdf: 1294765 bytes, checksum: b251b7430c83296db4d9b68caf60b016 (MD5) / Approved for entry into archive by José Jairo Viana de Sousa (jairo@ufc.br) on 2016-07-21T20:14:18Z (GMT) No. of bitstreams: 1 2011_dis_flbsilva.pdf: 1294765 bytes, checksum: b251b7430c83296db4d9b68caf60b016 (MD5) / Made available in DSpace on 2016-07-21T20:14:18Z (GMT). No. of bitstreams: 1 2011_dis_flbsilva.pdf: 1294765 bytes, checksum: b251b7430c83296db4d9b68caf60b016 (MD5) Previous issue date: 2011 / Faced with the need to seek higher yields and lower costs in saline areas, the use of organic fertilizers has been widely used in agriculture, as is the case of bovine biofertilizer, but studies show that its use as a minority of the adverse effects of salinity, has been little studied. The objective of this study was to evaluate the responses of cowpea to foliar application of biofertilizer under salinity conditions. The survey was conducted at the experimental farm Vale of Curu, at Pentecoste, Ceará, from november 2010 to january 2011. The plants were arranged in a split plot arrangement in a randomized block design with four blocks. The plot consisted of four different concentrations of salts in irrigation water via drip (0.5, 2.2, 3.6 and 5.0 dS m-1) and the subplots consisted of four levels of biofertilizers, corresponding to 0 , 15, 30 and 45% of the volume applied. The irrigation with saline water was dripping through and salts used to prepare the treatments were: NaCl, CaCl 2 .2H 2 O, MgCl 2 .6H 2 O in the proportion 7:2:1. In biofertilizer preparation was used fresh cattle manure and water in proportion (1:1). The doses of biofertilizers were applied weekly until the beginning of flowering. During the experiment were made manual weeding to control weeds and application of pesticides to control pathogens. In conducting the experiment were checked gas exchange, vegetative growth and assessed at the end of the pods were collected to assess productivity. Salinity influenced gas exchange (photosynthesis, stomatal conductance and internal CO 2 concentration), growth (dry matter and total), production (grain weight and yield) and nutrients (K / Na), without influence in other levels of minerals, nor the accumulation of salts in the soil. The influence of low salinity in the variables occurred due to high levels of rainfall (233.0 mm) during the experiment. Generally no significant effect was observed in the foliar application of biofertilizer, showing that application does not lessen the effect of saline irrigation. Due to the low influence of the biofertilizer the salinity of the water, it can be stated that the application can not be recommended for cultivation, requiring more studies, both in the form of application, as in proportion to be applied. / Diante da necessidade de se buscar altas produtividades e menores custos em áreas salinizadas, o uso de fertilizantes orgânicos vem sendo muito utilizado na agricultura, como é o caso do biofertilizante bovino, entretanto estudos mostram que sua utilização, como minorador dos efeitos adversos da salinidade, vem sendo pouco estudada. Objetivou-se com esse trabalho avaliar as respostas de plantas de feijão-de-corda à aplicação foliar de biofertilizante, sob condições de salinidade. A pesquisa foi realizada na fazenda experimental do Vale do Curu, em Pentecoste, Ceará, entre novembro de 2010 a janeiro de 2011. As plantas foram dispostas em um arranjo de parcelas subdivididas, no delineamento em blocos ao acaso, com quatro blocos. As parcelas consistiram de quatro diferentes concentrações de sais na água de irrigação, via gotejamento (0,5, 2,2, 3,6 e 5,0 dS m -1) e as subparcelas consistiram de quatro níveis de biofertilizante, correspondendo a 0, 15, 30 e 45% do volume aplicado. A irrigação com água salina foi via gotejamento e os sais utilizados para preparar os tratamentos foram: NaCl, CaCl 2 .2H 2 O, MgCl 2 .6H 2 O, na proporção 7:2:1. No preparo do biofertilizante foi usado esterco bovino fresco e água na proporção (1:1). As doses de biofertilizantes foram aplicadas semanalmente, até o inicio da floração. Durante o experimento foram feitas capinas manual, para o controle de ervas daninhas e aplicação de defensivos no controle de patógenos. Na condução do experimento foram verificadas trocas gasosas, avaliada o crescimento vegetativo e ao final foram coletas as vagens para avaliação da produtividade. A salinidade influenciou as trocas gasosas (fotossíntese, condutância estomática e concentração interna de CO 2 ), crescimento (matéria seca e total), produção (peso de grãos e produtividade) e nutrientes (relação K/Na), sem influência nos demais teores de minerais, nem tampouco no acúmulo destes sais no solo. A baixa influência da salinidade nas variáveis analisadas ocorreu, devido aos elevados índices de chuva (233,0 mm), durante o experimento. De um modo geral não foi observado efeito significativo na aplicação do biofertilizante via foliar, mostrando que aplicação não minorou o efeito da salinidade de irrigação. Devido à baixa influência do biofertilizante à salinidade da água, pode-se afirmar que, a aplicação pode não ser a recomendada para a cultura, necessitando de mais estudos, tanto na forma de aplicação, quanto na proporção a ser aplicado.

ASSIS JÚNIOR, José Otacílio de. Produtividade do feijão-de-corda e acúmulo de sais no solo em função da salinidade da água e da fração de lixiviação. 2007. 63 f. Dissertação (Mestrado em engenharia agrícola)- Universidade Federal do Ceará, Fortaleza-CE, 2007. / Submitted by Elineudson Ribeiro (elineudsonr@gmail.com) on 2016-06-23T19:20:43Z No. of bitstreams: 1 2007_dis_joassisjunior.pdf: 521347 bytes, checksum: 821b5d53b26acb580555447649a4aaa4 (MD5) / Approved for entry into archive by José Jairo Viana de Sousa (jairo@ufc.br) on 2016-07-21T20:16:46Z (GMT) No. of bitstreams: 1 2007_dis_joassisjunior.pdf: 521347 bytes, checksum: 821b5d53b26acb580555447649a4aaa4 (MD5) / Made available in DSpace on 2016-07-21T20:16:46Z (GMT). No. of bitstreams: 1 2007_dis_joassisjunior.pdf: 521347 bytes, checksum: 821b5d53b26acb580555447649a4aaa4 (MD5) Previous issue date: 2007 / The cowpea is a very important crop in the diet of the inferior social classes, but its productivity is very low, especially is non-irrigated areas. However, the irrigation in semi-arid areas has been associated to soil salinization. The study had the objective to evaluate the effect of water salinity and the leaching fraction on the growth and the productivity of grains of cowpea plants (Vigna unguiculata), cv, Epace 10. The experiment was set up in the experimental area of the Laboratório de Hidráulica e Irrigação/UFC, during the dry season. A completely randomized block design, with five repetitions, was adopted. Each experimental unit consisted of 4 lines of plantation of 5.0 m. The treatments studied were:: 1. Well water with ECw of 0.8 dS m-1 (without leaching fraction); 2. saline water with ECw of 5.0 dS m-1 (without leaching fraction); 3. saline water with ECw of 5.0 dS m-1 with leaching fraction of 0.14; and 4. saline water with ECw of 5.0 dS m-1 with leaching fraction of 0.28. During the flowering and fruit development four measurements of gas exchange and three determinations ion concentrations (Na+, Ca+2, K+, and Cl-) were performed. At the end of the crop cycle, some parameters of vegetative growth and plant yield, and salt accumulation in the soil were observed. The saline water application provoked salt accumulation in the soil profile, but this effect was partially reverted by the increase of the leaching fraction. Salinity reduced plant yield, but it did not affect its quality and caused a 10% increase in the harvest index. The reduction in plant yield was related, at least in part, to decrease in net assimilation of carbon during flowering and fruit development due to osmotic effects and to accumulation of potentially toxic ions. In general, the increase in leaching fraction did not reduce the effect of the salinity on plant development. / O feijão-de-corda é uma cultura muito importante na dieta das camadas sociais inferiores. O baixo rendimento dessa cultura faz com que cada vez mais a irrigação venha como ferramenta para auxiliar no aumento da produtividade. Porém, com o advento da irrigação o problema da salinidade aumentou bastante. Neste trabalho, avaliou-se o acúmulo de sais no solo e a produtividade do feijão-de-corda [Vigna unguiculata (L.) Walp.], cv. Epace 10, em função da fração de lixiviação e da salinidade da água de irrigação. O experimento foi realizado durante a estação seca na área experimental do Laboratório de Hidráulica e Irrigação/UFC, seguindo um delineamento em blocos ao acaso, com quatro tratamentos e cinco repetições, sendo que cada parcela consistiu de 4 linhas de plantio com o comprimento de 5,0m. No tratamento 1 as plantas foram irrigadas com água do poço (CEa = 0,8 dS m-1), sem fração de lixiviação; os tratamentos 2, 3 e 4, consistiram de água salina com CEa de 5,0 dS m-1, sem fração de lixiviação, com fração de lixiviação de 0,14 e 0,28, respectivamente. Durante as fases de floração e frutificação foram feitas quatro avaliações de trocas gasosas foliares e três determinações dos teores de Na+, Ca+2, K+ e Cl-. Ao final do ciclo foram determinadas parâmetros de crescimento vegetativo e reprodutivo, bem como o acumulo de sais no solo. A aplicação de água salina provocou acúmulo de sais no solo, porém esses efeitos foram parcialmente revertidos pelo aumento da fração de lixiviação; a salinidade reduziu a produtividade de grão, porém não afetou sua qualidade e provocou um aumento de 10% no índice de colheita; a redução na produtividade ocasionada pela salinidade da água deveu-se, em parte, à redução na assimilação líquida de carbono durante as fases de floração e frutificação, associada aos efeitos osmóticos e ao acúmulo de íons potencialmente tóxicos nos tecidos foliares; as frações de lixiviação não tiveram muita influência na superação dos danos provocados pela salinidade sobre a produtividade das plantas.

AQUINO, Alexandre José Silva de. Avaliação do crescimento e de mecanismos de tolerância à salinidade em plantas de sorgo forrageiro irrigados com águas salinas. 2005. 89 f. : Dissertação ( mestrado) - Universidade Federal do Ceará, Centro de Ciências Agrárias, Curso de Mestrado em Agronomia, Fortaleza-CE, 2005. / Submitted by demia Maia (demiamlm@gmail.com) on 2016-06-02T13:25:52Z No. of bitstreams: 1 2005_dis_ajsaquino.pdf: 426079 bytes, checksum: 0a30bd700ba37eab5d425f683fa5d132 (MD5) / Approved for entry into archive by demia Maia (demiamlm@gmail.com) on 2016-06-02T13:26:22Z (GMT) No. of bitstreams: 1 2005_dis_ajsaquino.pdf: 426079 bytes, checksum: 0a30bd700ba37eab5d425f683fa5d132 (MD5) / Made available in DSpace on 2016-06-02T13:26:22Z (GMT). No. of bitstreams: 1 2005_dis_ajsaquino.pdf: 426079 bytes, checksum: 0a30bd700ba37eab5d425f683fa5d132 (MD5) Previous issue date: 2005 / This work studied the tolerance of two genotypes of forrage sorghum (Sorghum bicolor (L) Moench), one salt sensitive (CSF 18) and another salt tolerant (CSF 20). Selected seeds were germinated in vases containing 12 Kg of sandy soil under greenhouse conditions. Ten days after seeding, plants were irrigated with different salt concentration water. For prepairing saline solutions, NaCl, CaCl2.2H2O e MgCl2.6H2O salts were used solved in destyled water, on proportion 7:2:1. the randomized completely design was used, and the treatments were outlined according to a 2 x 5 factorial arrangment, composed with two genotypes and five tratments of increasing salinity (0.5, 2.0 , 4.0, 6.0 e 8.0 dS.m-1), with five replicates. During vegetative growth measures of photosyntesis and gas exchanges were made. Fourty four days after germination, plants were harvested. The contents measured were morpholocial characteristics, shoot fresh and dry matter production (leaves, blades and colms) and water potential. Roots were colected with soil samples in three deaphts (10, 20 e 30 cm). Solute contents of shoot and soil samples were determinated. The genotype CSF 20 showed higher values of internode number, plant height and colm diameter. The reductions of growth were higher for CSF 18 genotype, when plants were exposed to the higher salt levels irrigation water. The relation of K+ in colms and leaves were lower in genotype CSF 20, sugesting that this genotype shows a higher capacity of distribution of K+ in leaves. The genotype CSF 20 showed higher accumulation of soluble carbohydrates in leaves. Results showed that CSf 18 genotype was most sensible to water salinity and CSF 20 was most tolerant to water salinity. / Neste trabalho foi avaliada tolerância de dois genótipos de sorgo forrageiro (Sorghum bicolor (L) Moench), considerados sensível (CSF 18) tolerante (CSF 20) ao estresse salino. Sementes selecionadas foram germinadas em vasos contendo 12 kg de solo arenoso em condições casa de vegetação. Dez dias após a semeadura as plantas passaram a ser irrigadas com água de diferentes concentrações de sais. Para o preparo das soluções salinas, foram utilizados os sais de NaCl, CaCl2.2H2O e MgCl2.6H2O dissolvidos em água destilada, na proporção de 7:2:1. O delineamento experimental foi inteiramente casualizado, em esquema fatorial 2 x 5, composto por dois genótipos, cinco tratamentos em doses crescentes de água salina (0.5, 2.0 , 4.0, 6.0 e 8.0 dS.m-1) e cinco repetições. Durante a fase de crescimento vegetativo foram realizadas medições de fotossíntese e trocas gasosas nas plantas. A coleta das plantas teve início quarenta e quatro disa após o início dos tratamentos. Foram realizadas medições de características morfológicas, massas seca e fresca das partes aéreas das plantas (limbos, bainhas e colmos) e potencial hídrico. As raízes foram coletadas, juntamente com amostras de solo em três profundidades (0.10, 0.20 e 0.30 m). Foram determinados os teores de íons das partes aéreas e das amostras de solo. O genótipo CSF 20 apresentou maiores valores de número de entrenós, altura da planta, diâmetro do colmo. As reduções dos padrões de crescimento foram maiores para o genótipo CSF 18, quando as plantas foram expostas aos maiores níveis de salinidade da água de irrigação. A relação entre os teores de K+ nos colmos e nos limbos foliares foram bem menores no genótipo CSF 20, sugerindo que esse genótipo apresenta maior capacidade de distribuição de K+ para as folhas. Os maiores valores na relação Na+/K+ foram observados no genótipo CSF 18 em função de sua menor capacidade de acumular K+ nas folhas. O genótipo CSF 20 acumulou maior quantidade de carboidratos solúveis nas folhas. Os resultado mostraram que o genótipo CSF 18 mostrou-se sensível à salinidade, enquanto que o genótipo CSF 20 mostrou-se tolerante à salinidade.