The biological treatment of metalworking fluids (MWFs) is a cost effective alternative to conventional waste disposal processes. While research has proven that this process is capable of treating large volumes of wastes with high organic concentrations, there are uncertainties about the mechanisms by which the treatment occurs, and there are limitations that must be overcome. There is a need to understand the importance of the mechanisms by which carbon (and hence COD) is removed from the wastewater. This will allow for waste practitioners to make better decisions for optimizing the process, and for disposing of waste (i.e sludge) that is generated. The biological treatment process is also susceptible to biocides present within formulations. These compounds either need to be removed before the treatment process, or the bioreactors need to be made more resistant to them to ensure that their presence does not hinder the reactor functioning. This study aims to answer the uncertainties about the carbon removal mechanisms involved in the treatment of oil-containing MWFs. In the first experimental chapter, it is shown that the predominant mechanism of carbon removal is oil/water separation induced by emulsifier degradation, and hence the bioprocess treatment rate is significantly affected by the biodegradability of surfactants and by the presence of cations found naturally in the water that used to prepare the emulsions. The study then provides insights into the potential that coagulation and coalescence has for removing inhibitory components commonly found in MWFs. Coagulation and coalescence is shown to effectively remove biocides with low aqueous solubility (iodopropynyl butylcarbamate) and those that partition themselves into the oil phase (o-phenyl phenate and its sodium salt). Finally, to improve the resistance of reactors to inhibitory compounds, factors influencing the development of fixed-film reactors are investigated. A micro-cosmic system is used to study the both physico-chemical effects and nutritional factors on the development of biofilm reactors. It is shown that biofilm yields can be controlled through pH adjustment, and that these yields are maximized with phosphate stimulation and ammonium limitation. It is then shown that fixed-film reactors are able to treat metalworking fluids even under conditions deemed to be inhibitory. In summary, this project provides insights into further understanding and enhancing the biological treatment of MWFs.

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Produced water (PW) is an oil and gas extraction byproduct that contains a variety of contaminants. PW was traditionally disposed of in deep injection wells or released into the environment. However, these practices may have environmental consequences. The reuse of PW for power water injection (PWI) can help to reduce these impacts by providing a renewable source of water that can be used to maintain production pressure and increase oil recovery. Additionally, the reuse of PW can save oil companies money on water treatment, transporting and disposal costs. Ultrafiltration membranes are used to separate oil from water in produced water. However, ultrafiltration membranes are susceptible to severe fouling by oil molecules, which can reduce their performance. This research investigated the use of Pebax® coating to improve the performance of ultrafiltration membranes for oily-water mixture. The results showed that Pebax® coating can enhance the resistance of membranes to fouling to fouling. The optimal balance between fouling resistance and water flux was found to be achieved by applying very thin coating layers and using appropriate solvents (e.g., n-Butanol). The Pebax® coating creates an essentially defect-free layer on the membrane surface, as seen by the SEM images. Additionally, the coated membranes outperformed the untreated membranes in terms of fouling resistance. This result demonstrated that oil molecules showed less adhesion on the surface and penetration inside membrane pores, thus reducing fouling. Overall, the findings of this research point to PEBAX® coating as a potential means of enhancing the ability of ultrafiltration membranes to resist fouling in the process of separating oil from water. To analyze the long-term performance of coated membranes and to optimize the coating procedure, additional research is required.

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This dissertation delves into the theory, design and fabrication, and practical uses of synthetic trees that replicate the transpiration mechanisms of natural trees. The first chapter provides an in-depth explanation of how natural trees utilize hydraulic mechanisms to draw water from the soil, through their roots, and up to their leaves, sustaining hydration through transpiration. This process is reliant on the difference in relative humidity between the leaf and the ambient to promote evaporation, and synthetic trees replicate this cycle by integrating reservoirs and conduits with wetted nanopores, mimicking the negative Laplace pressure seen in natural trees. Chapter 2 presents a detailed theoretical framework for transpiration in synthetic trees. These trees feature a vertical array of tubes connected to a nanoporous synthetic leaf. Our model considers the impact of convective gas flow on the leaf, minimizing the diffusive boundary layer and directly influencing the leaf's negative Laplace pressure. We next analyze how the rate of evaporation and tree morphology affect the required Laplace pressure for mass conservation, in an ambient environment with an appreciable diffusive boundary layer. Our model considers the changing dynamics of the menisci, including their capability to adjust their contact angle and withdraw into nanopores to self-stabilize. We then determine conditions where transpiration is limited by evaporation or constrained by the leaf's maximum Laplace pressure, across various tree geometries and ambient conditions. In Chapter 3, the focus shifts to a practical application, as the insights from the previous chapters guide the creation of a synthetic tree for water harvesting. Solar steam generation employing a porous evaporator, with a 3D design extending beyond the free surface to mitigate heat losses, is used to demonstrate how transpiration, rather than capillarity, can raise water up glass tubes, and improve liquid transport heights over conventional methods. Chapter 4 expands on the synthetic tree concept, proposing a mobile desalination water container driven by transpiration. The container features a ring-shaped fin designed to absorb solar heat, increasing water evaporation from a nanoporous synthetic leaf. This approach combines reverse osmosis and thermal evaporation, offering a promising solution for obtaining fresh water from seawater. In Chapter 5, the study explores transpiration-powered oil-water filtration using synthetic trees. Our approach showcases the potential for natural separation of oil and water in various applications, without the need for a pump and in opposition to gravity. Chapter 6 modifies the synthetic tree design to selectively absorb and retain oil from oil-water emulsions. When water evaporates from the synthetic leaf, enabled by the generated negative suction within, oil is then drawn and contained within the system through oleophilic and hydrophobic membranes. This approach offers a sustainable method for oil spill clean-up, oil extraction and purification. Chapter 7 experimentally investigates how to eliminate the capillary driving force in synthetic trees. By over-filling the synthetic leaf's top surface to remove existing concave menisci, the study hypothesizes gravity as a replacement mechanism for negative pressure, with the water in hydrostatic columns held in tension by the overlying water supported within the porous leaf. In summary, these engineered hydraulic systems offer novel approaches to water harvesting, desalination, oil-water filtration, and the cleanup of oil spills, and the study of synthetic trees opens up a realm of possibilities for sustainable water management and environmental remediation, showcasing the potential of biomimicry in solving pressing global challenges. / Doctor of Philosophy / This dissertation explores the concept of synthetic trees designed to mimic the transpiration cycle of natural trees for various applications. The first chapter provides a detailed explanation on how this is achieved. The second chapter introduces the theoretical model, highlighting the interplay between suction pressure, spontaneous flow, and tree geometry in surface tension powered water flow. In Chapter 3, the findings inform the design of a synthetic tree for water harvesting through solar steam generation. Overcoming constraints of floating evaporators, this tree demonstrates enhanced water condensation compared to traditional reservoirs, and the use of transpiration in the tubes allow for greater height flexibility. Chapter 4 presents a theoretical design for a portable desalinating water bottle powered by transpiration. Inspired by mangrove trees, the bottle utilizes solar heat absorption, a nanoporous synthetic leaf, and reverse osmosis to spontaneously enable desalination. The hybrid approach enhances thermal evaporation and pre-filters salt, potentially producing a daily extraction of one liter of fresh water from seawater. Chapter 5 explores oil-water filtration using surface tension power in synthetic trees. Operating without pumps and against gravity, this spontaneous phase separation demonstrates potential applications in oil spill cleanup, wastewater purification, and oil extraction. In Chapter 6, the synthetic tree is further modified to selectively take up and contain only oil from an oil-water emulsion. Driven by the surface tension mechanism, oil enters the tree through oil loving and water membranes, yielding high-purity oil samples, and offering innovative solutions for various environmental and industrial challenges. Chapter 7 investigates how to stop capillary forces in synthetic trees. When water evaporates from the leaves, it creates suction, pulling water from the soil through the xylem to keep the tree hydrated. We filled the top of the synthetic leaf to remove the curved surfaces that cause capillary tension. Surprisingly, water in the vertical tubes still held against gravity. This led us to consider a new idea: gravity might be replacing surface tension, with columns of water in the tree held in tension by the water above them in the leaf. Overall, this research on synthetic trees suggests exciting new ways to address environmental issues and manage water resources sustainably, underlying the power of nature-inspired solutions.

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Submitted by Kilvya Braga (kilvyabraga@hotmail.com) on 2018-04-19T12:49:52Z No. of bitstreams: 1 ANTUSIA DOS SANTOS BARBOSA - TESE (PPGEQ) 2015.pdf: 4188064 bytes, checksum: b6d46e877c5fce328aa4e68c61e9dcb9 (MD5) / Made available in DSpace on 2018-04-19T12:49:52Z (GMT). No. of bitstreams: 1 ANTUSIA DOS SANTOS BARBOSA - TESE (PPGEQ) 2015.pdf: 4188064 bytes, checksum: b6d46e877c5fce328aa4e68c61e9dcb9 (MD5) Previous issue date: 2015 / As membranas zeolíticas têm despertado interesse nos pesquisadores em processos de separação e catálise, uma vez que elas apresentam elevada estabilidade térmica e química, são altamente seletivas, devido ao potencial no peneiramento molecular. A inovação deste estudo se dá na síntese da membrana zeolítica Y/ɣ-alumina para separação óleo/água. Este trabalho teve como objetivos: preparar a zeólita Y via síntese hidrotérmica, ɣ-alumina pelas decomposições do sulfato de alumínio e acetato de alumínio e membranas zeolíticas utilizando 3 métodos distintos: transporte a vapor e crescimento secundário: dip-coating e rubbing. Os produtos obtidos foram caracterizados por DRX, Adsorção Física de Nitrogênio, MEV, ATD e TG, FRX-ED e Porosimetria de Mercúrio. Além da síntese e caracterização, numa segunda etapa as membranas zeolíticas foram avaliadas no processo de remoção óleo/água de um efluente sintético, utilizando uma coluna de separação por membrana. Os ensaios foram realizados nas condições de concentração inicial do óleo 500 mg.L-1, Temperatura igual a 25 °C e Pressão atmosférica, permitindo observar a variação da concentração do permeado em (mg.L-1) e o coeficiente de rejeição (R%). Para síntese da alumina foram utilizadas os precursores sulfato de alumínio e acetato de alumínio, utilizando temperaturas de decomposição de 1000 ºC e 850 °C, respectivamente. Foi selecionada a alumina que obteve menor custo operacional, ou seja, ɣ-alumina oriunda da decomposição térmica do sulfato de aluminio. A zeólita Y e as membranas zeolíticas Y/ɣ-alumina foram preparadas em condições hidrotérmica, com temperatura de 90 ºC, durante 7 horas. Foram realizadas modificações térmicas (500, 600, 700, 750, 800, 900, 950, 1000 e 1100 °C) por período de 1 e 2 horas no sulfato de alumínio (após moagem, conformação e compactação). Baseado nos resultados de DRX pode-se concluir que: (i) os materiais de partida (sulfato de alumínio e acetato de alumínio), evoluem termicamente, resultando como produto final em ɣ-alumina; (ii) é possível obter a zeólita Y; observou-se também a formação dos suportes cerâmicos ɣ-alumina, após sinterização. O estudo térmico realizado no suporte cerâmico (DTSA) evidenciou que a temperatura ótima deve limitar-se em valores entre 700-750 °C/1h. O maior valor de cristalinidade foi observada para o suporte tratado a 700 °C/1h. O mesmo foi classificado como um material mesoporoso podendo ser utilizados em processos de ultrafiltração (UF). Os resultados obtidos por caracterização das membranas zeolíticas evidenciaram que as mesmas foram obtidas com sucesso independente do método utilizado. Dos testes de separação da emulsão óleo/água pode-se concluir que a inserção da zeólita (Y) ao suporte cerâmico (ɣ-alumina) melhorou o processo de separação da emulsão óleo/água. Como conclusão geral, as membranas zeolíticas obtidas utilizadas em coluna de separação por membrana são bastante promissoras no processo de separação emulsão óleo/agua. / The zeolite membranes have attracted attention of researchers in separation processes and catalysts since they have high thermal and chemical stability, are highly selective because of the potential on the molecular sieve. The innovation of this study gives the synthesis of zeolite membrane Y/ɣ-alumina for oil/water separation. This study aimed to: prepare the zeolite Y via hydrothermal synthesis, ɣalumina by decomposition of aluminum sulfate and ethyl aluminum and zeolite membranes using three different methods: steam transportation and secondary growth: dip-coating and rubbing. The products obtained were characterized by XRD, nitrogen adsorption of Physics, SEM, DTA and TG, ED-XRF and Porosimetry Mercury. In addition to the synthesis and characterization in a second step the zeolite membranes were evaluated in the process of removing oil/water of a synthetic effluent using a column separation membrane. Assays were performed under the conditions of the initial oil concentration 500 mg.L-1, temperature of 25 °C and atmospheric pressure, allowing to observe the change in concentration of the permeate (mg.L-1) and the rejection coefficient ( R%). For synthesis of the precursors used were alumina aluminum sulfate and aluminum acetate using decomposition temperatures of 1000 °C and 850 °C respectively. Was selected alumina which had lower operating costs, so, ɣ-alumina originating from the thermal decomposition of aluminum sulfate. The zeolite Y and zeolite membranes Y/ɣ-alumina were prepared in hydrothermal conditions, with a temperature of 90 for 7 hours. Thermal changes were performed (500, 600, 700, 750, 800, 900, 950, 1000 and 1100 °C) per period of 1 hour and 2 hours in aluminum sulphate (after milling, shaping and compacting). Based on the XRD results it can be concluded that: (i) the starting materials (aluminum sulphate and aluminum acetate) to evolve heat, resulting in a finished product ɣ alumina; (ii) it can get the zeolite Y; It also noted the formation of ɣ-alumina ceramic brackets after sintering. Thermal study on ceramic support (DTSA) showed that the optimum temperature should be limited to values between 700-750 °C/1h. The greatest amount of crystallinity was observed for material treated at 700 °C/1h. The same was classified as a mesoporous materials can be used in ultrafiltration process (UF). The results of the characterization of the zeolite membranes showed that they were obtained with successful independent of the method used. From tests separation of the emulsion oil/water can be concluded that the insertion of zeolite (Y) to the ceramic support (ɣ-alumina) improved separation process of the oil/water emulsion. As a general conclusion, the obtained zeolite membranes used in membrane separation column are very promising in the separation process oil / water emulsion.