O crescimento acelerado da população mundial e o consequente aumento da produção de bens de consumo tem impulsionado uma crise na disponibilidade de recursos naturais, principalmente os hídricos. Diante da escassez de recursos hídricos, processos de tratamento de efluentes industriais e domésticos que visam o descarte zero de líquido (ZLD - Zero Liquid Discharge) vêm sendo cada vez mais estudados. Atualmente, diversos processos têm sido empregados com este propósito. No entanto, ainda há a geração, juntamente com a água recuperada, de uma corrente composta por uma solução salina concentrada, cuja composição normalmente é constituída por diferentes tipos de sais inorgânicos. Uma das formas de alcançar o descarte zero de líquidos é por meio da implementação de um processo adicional de separação, sendo a cristalização evaporativa considerada viável para essa finalidade. O emprego deste processo é limitado ao controle das características morfológicas das partículas obtidas, visto que estas influenciam diretamente na efetividade de separação dos processos subsequentes à cristalização (filtração, centrifugação). Além disso, efluentes industriais são soluções complexas, e a utilização da cristalização envolve a presença de mais de um sal em solução (co-cristalização). Este processo é pouco investigado na literatura científica, logo, a determinação de condições de processos visando controlar a características destas partículas não é trivial. Neste trabalho, foram estudados o efeito da taxa de evaporação e da presença de sementes na morfologia, composição, tamanho e hábito de partículas de cloreto de sódio e sulfato de cálcio obtidas por co-cristalização evaporativa em bateladas. Os resultados serviram para a determinação de parâmetros de operação para a co-cristalização visando a obtenção de partículas com elevado tamanho médio e baixa dispersão de tamanhos. Taxas de evaporação elevadas favoreceram a obtenção de aglomerados de partículas. A presença de sulfato de cálcio em solução resultou em partículas maiores, menos polidispersas e com menor grau de aglomeração. Tal resultado foi considerado positivo, visto que, estas características são desejáveis para a separação dos cristais da solução mãe. Foi também observado que as sementes de hemihidrato atuam inibindo a aglomeração dos cristais de NaCl. O aumento da quantidade de sementes destes sais culminou na obtenção de partículas menos aglomeradas, porém houve um alargamento das distribuições de tamanho de partículas. Nos experimentos em que foram utilizadas sementes de ambos os sais, o mesmo efeito na aglomeração foi observado. Em todos os experimentos com semeadura de hemihidrato, foi observada a aglomeração deste sal com o NaCl, que foi intensificada com o aumento da taxa de evaporação e com o aumento da concentração de sementes. Foi identificada a possibilidade de recuperação de ambos os sais e obtenção - em determinadas condições - de mais de 90% do NaCl com até 99,50% de pureza. / The accelerated growth of the world population and the consequent increase in the production of consumer goods, has driven to a crisis in the availability of natural resources, especially water. Due to the scarcity of water resources, industrial and domestic wastewater treatment processes that aim the Zero Liquid Discharge (ZLD) have been increasingly studied. Nowadays, several processes have been used for this purpose. However, in all of them, there is still the generation of a brine composed of a concentrated salt solution, concomitantly with the recovered water, whose composition is normally constituted by different types of inorganic salts. One way to achieve the ZLD is through the implementation of an additional separation process, for which the evaporative crystallization is considered technically viable for this purpose. The use of this process is limited to the control of the morphological characteristics of the particles obtained, since this influences directly the separation effectiveness of the downstream processes to crystallization (filtration, centrifugation). Besides, industrial effluents are complex solutions and its crystallization involves the presence of more than one salt in solution (cocrystallization). This process is still not well investigated on scientific literature, thus, the determination of process conditions aiming to control the characteristics of these particles is not trivial. In this work, the effect of the evaporation rate and the presence of seeds on the morphology, composition, size and habit of sodium chloride and calcium sulfate particles obtained by batch evaporative co-crystallization were studied. The results were used to determine the operating parameters for the cocrystallization in order to obtain particles with high average size and narrow dispersion of sizes. High evaporation rates favored the obtaining of agglomerated particles. The presence of calcium sulfate in solution resulted in larger particles, less polydisperse and with less degree of agglomeration. Such result was considered positive, since, these characteristics are desirable for the separation of the crystals from the solution. Seeds of hemihydrate inhibited the agglomeration of the NaCl crystals. The increase in seed load of hemihydrate culminated in obtaining less agglomerated particles, but there was an increase in particle size distributions. In the experiments in which seeds of both salts were used, the same effect in the agglomeration was observed. In all experiments with seeds of hemihydrate, agglomeration of this salt with NaCl was observed, which was intensified with increasing evaporation rate and increasing seed amount. It was identified the possibility of recovery of both salts and, for certain conditions, obtaining more than 90% of NaCl with up to 99.50% purity.

abstract: Hydrogel polymers have been the subject of many studies, due to their fascinating ability to alternate between being hydrophilic and hydrophobic, upon the application of appropriate stimuli. In particular, thermo-responsive hydrogels such as N-Isopropylacrylamide (NIPAM), which possess a unique lower critical solution temperature (LCST) of 32°C, have been leveraged for membrane-based processes such as using NIPAM as a draw agent for forward osmosis (FO) desalination. The low LCST temperature of NIPAM ensures that fresh water can be recovered, at a modest energy cost as compared to other thermally based desalination processes which require water recovery at higher temperatures. This work studies by experimentation, key process parameters involved in desalination by FO using NIPAM and a copolymer of NIPAM and Sodium Acrylate (NIPAM-SA). It encompasses synthesis of the hydrogels, development of experiments to effectively characterize synthesized products, and the measuring of FO performance for the individual hydrogels. FO performance was measured using single layers of NIPAM and NIPAM-SA respectively. The values of permeation flux obtained were compared to relevant published literature and it was found to be within reasonable range. Furthermore, a conceptual design for future large-scale implementation of this technology is proposed. It is proposed that perhaps more effort should focus on physical processes that have the ability to increase the low permeation flux of hydrogel driven FO desalination systems, rather than development of novel classes of hydrogels / Dissertation/Thesis / Masters Thesis Mechanical Engineering 2019

Future nanofiltration (NF) membranes used for selective separations of ions and small organic molecules must maintain performance in environments where high concentrations of total dissolved solvents or foulants are present. These challenges can be addressed through the development of composite membranes, as well as the engineering of enhanced surface properties and operating conditions for existing commercial membranes. In this work, ion transport through commercial thin film composite (TFC) polyamide NF membranes were studied in both lab-prepared salt solutions and industrial wastewater. The dependence of several variables on ion rejection was investigated, including ion radius, ion charge, ionic strength, and temperature. The impact of scaling and increasing ionic concentration on membrane performance during recovery of industrial wastewater was investigated. Fouling of the membrane surface was reduced by enhancing commercial NF membrane surfaces via aqueous-phase esterification of lignin sulfonate. NF membranes were also created utilizing an ionic liquid solvent (1-ethyl-3-methylimidazolium acetate) to integrate composite materials into cellulose. Composite materials such as graphene oxide quantum dots, iron III particles, and lignin have been shown to be interact strongly with cellulose in solution with ionic liquid and bind together cellulose chains via hydrogen bonds following nonsolvent induced phase inversion. Studies suggest the composite materials modify membrane surface chemistry and improve selectivity of small organic molecules (~300 nm) while allowing for the complete passage of ions.

Renewable energy is one of the most reliable resource that can be used to generate the electricity. It is expected to be the most highly used resource for electricity generation in many countries in the world in the next few decades. Renewable energy resources can be used in several purposes. It can be used for electricity generation, water desalination and mining. Using renewable resources to desalinate the water has several advantages such as reduce the emission, save money and improve the public health. The research described in the thesis focuses on the analysis of using the renewable resources such as solar and wind turbines for desalination plant. The output power from wind turbine is connected through converter and the excess power will be transfer back to the main grid. The photo-voltaic system (PV) is divided into several sections, each section has its own DC-DC converter for maximum power point tracking and a two-level grid connected inverter with different control strategies. The functions of the battery are explored by connecting it to the system in order to prevent possible voltage fluctuations and as a bu er storage in order to eliminate the power mismatch between PV array generation and load demand. Computer models of the system are developed and implemented using the PSCADTM / EMTDCTM software.

<p>U okviru ove doktorske disertacije prikazan je holistiĉki pristup proučavanju objekata kulturnog nasleđa, koji je podrazumevao postavljanje metodologije ispitivanja originalnih istorijskih materijala, simulacije procesa degradacije na laboratorijski pripremljenim model supstratima, kao i razvoj novih materijala koji imaju funkciju či&scaron;ćenja degradiranih struktura. Kroz multidisciplinaran istraživački rad je izvr&scaron;ena je detaljna dijagnostika stanja srednjevekovne tvrđave Bač, procesirani su (proizvedeni i ve&scaron;tački ostareni) model supstrati opeka tako da poseduju slične karakteristike kao i ispitivani istorijski materijali, razvijene su i primenjenje glinene pulpe i na bazi njih projektovani su bioaktivni sistemi za uklanjanje nitratnih soli. Ovi novorazvijeni sistemi predstavljaju kombinaciju glinenih pulpi srednje efikasnosti koje imaju ulogu nosača bakterijske kulture Pseudomonas stutzeri, koja povećava kapacitet či&scaron;ćenja razvijenih glinenih pulpi. Rezultati ispitivanja efikasnosti bioaktivnih sistema pokazali su da upotreba suspenzije P.stutzeri (direktno naneta ili ume&scaron;ana u projektovane pulpe) dovodi do značajnog povećanja kapaciteta či&scaron;ćenja polaznih pulpi, odnosno do formiranja sistema visoke efikasnosti za proces desalinacije nitratnih soli. Pored laboratorijske primene, novorazvijeni bioaktivni sistem primenjen je u realnim uslovima na severoistočnom bedemu Tvrđave Bač varijacijom procedura nano&scaron;enja (jednostepene, dvostepene i trostepene primene). Ovaj sistem pokazao je vi&scaron;e pozitivnih performansi u realnim uslovima primene u odnosu na očekivanja bazirana na laboratorijskim istraživanjima. Na osnovu svih eksperimentalnih podataka dobijenih u okviru laboratorijskih istraživanja razvijen je algoritam (Matematičko modelovanje ve&scaron;tačkih neuronskih mreža). Ovaj algoritam bi u budućnosti svoju primenu mogao naći u predviđanju pona&scaron;anja razvijenih sistema na drugim supstratima čija je poroznost poznata, čime se skraćuje vreme projektovanja desalinacionih sistema za druge objekte.</p> / <p>The research approach to cultural heritage degradation and protection, presented in this thesis is a holistic one. It involved establishment of methodology for the investigation of original historical materials, the simulation of the degradation processes on laboratory prepared model substrates, as well as the development of novel materials with cleaning function for degraded structures. The thesis encompasses a detailed diagnostics of the medieval Baĉ Fortress, processing (manufacturing and artificial weathering) of brick model substrates with the characteristics similar to the investigated historical materials, and finally, the development and application of clay poultices which were the basis for the design of bioactive systems for the reduction of nitrate salts. These newly developed systems present a combination of moderately efficient clay poultices that are used as a carrier for bacterial culture Pseudomonas stutzeri. These bacteria had a role of increasing the cleaning capacity of the developed clay poultices. The results of the investigation of the efficacy of the developed systems showed that the use of P. stutzeri suspension (directly applied or mixed in the designed poultices) leads to a significant increase of the cleaning capacity of the developed poultices and to the formation of highly efficient bioactive systems for desalination of nitrate salts. Apart from laboratory application, the most efficient newly developed bioactive system was applied in real environmental conditions on the north-eastern rampart of Baĉ fortress, by varying the application procedure (one-step, two-step and three-step application). This system showed more positive performances in real environmental conditions of application compared to the expectations based on laboratory investigations. Based on all the experimental data obtained within laboratory investigations, an algorithm (mathematical modelling of artificial neuron networks) was programed. The developed model could find its application in the assessment of the application parameters of the developed systems on other substrates with known porosity. This would greatly decrease the time needed for the design of desalination systems for other objects.</p>

Reverse Osmosis (RO) is widely accepted as an alternative method to produce freshwater from different feed water sources. This technology competitively substitutes the thermal processes in the near future because of several advantages particularly in energy saving. The success of RO operation will, however, depends largely on the overall membrane performance. Deposit or build-up of solute is one of the main reasons for membrane operation failure. Build-up of solute or deposit which is known as fouling and scaling will decrease the permeate flux and increase the energy consumption in particular after prolonged operation of RO. The thesis presents the experimental results obtained in a small-scale RO system. The aim of this study is to investigate the effect of sodium chloride and calcium carbonate on the membrane performance and subsequent build-up of solute on the membrane surface. The experiments were carried out in a small-scale of RO (2 m3/day capacity) with spiral wound membrane using simulated feed water, secondary effluent, and groundwater samples. The parameters chosen for the experiments are applied pressure (1250-4750 kPa), and concentration of sodium chloride (l00-5000 mg/L) and calcium carbonate (50-100 mg/L). / The results from feedwater runs indicated that initial sodium chloride and calcium carbonate in feed water and applied pressure affects the overall membrane performance. However, there is no significant effect on membrane performance for sodium chloride with concentration below 1200 mg/L and applied pressure lower than 2250 kPa. Applied pressure appears to have an impact on build-up of sodium and calcium on the membrane surface for pressures greater than 2750 kPa. For typical small-scale RO system used in this experiment, build-up of calcium will slightly decrease with given pressure caused by the characteristic of membrane that easily removes the divalent ions. The osmotic pressure of solution also strongly affects the permeate flow rate in particular for relatively higher sodium concentration (> 2500 mg/L). As a consequence of higher osmotic pressure, zero permeate flux is achieved when sodium chloride concentration was greater than 5000 mg/L and applied pressure lower than 1750 kPa. Results also indicated that fouling might pose a potential problem in small-scale RO operation. In order to investigate the membrane performance, experiments with secondary effluent samples were also performed. Results indicated that water recovery percentages and permeate flux also linearly increase with applied pressure. However, effectiveness of membrane decreases less than 98% otherwise build-up of solute tends to increase. It is suggested that lower values of the water recovery percentage (WRP) and permeate flux (Jw) are caused by the characteristic of secondary effluent that have high-suspended solids, organic carbon, and minerals. Further, the membrane performance also examined with ground water as feed water sample. / Results showed that both water recovery percentage and permeate flux linearly increased with operating pressure. However, intensive pretreatment are required as a result of higher concentration of humic acid and iron in raw feed. Percentages of ion rejection for sodium and calcium are greater than 98 and 99% respectively. The high ion rejections are mainly due to the characteristics of groundwater with low TDS and EC. Sodium and calcium build-up in a small-scale RO system considered appears to be affected by the applied pressure. Build-up of solute in small-scale of RO system has been predicted using the empirical model proposed in this work. Two ions namely sodium and calcium in feed water considered as predominant ions responsible for fouling and scaling on the membrane surface. Four main parameters namely, applied pressure (P), permeate flux (Jw), membrane resistance (Rm), and feed concentration (Cf) are considered which strongly affect the overall membrane performance. The empirical correlations derived from experimental observation among these parameters can be expressed as follows: In Md NaCI = O. 77 In P + 0.67 In Jw + 0.19 In Rm + 0.171n Cf In Md CaCO3= 0.96 In P + 0.75 In Jw + 0.2 In Rm - 0.07 In Cf / The empirical models proposed in this thesis may be useful for predicting the buildup of solute on the membrane surfaces. In the present work, an attempt has been made to estimate the energy consumption and unit cost for desalting of different feed water samples in a small-scale RO system. In RO plants, unit cost of water production from feed water is primarily governed by the energy required for pumping raw water. Estimates of specific energy consumption (SEC) for desalting of sodium chloride, combined sodium and calcium carbonate solutions were found to be in the range of 0.79 - 3.21 and 0.81 - 3.22 kwh/m3 respectively. For groundwater and secondary effluent, they are estimated to 0.63 - 1.71 and 0.79 - 2.02 kWh/m3 respectively. Moreover, energy consumption for different feed water samples was used to estimate the unit cost for water production. Estimation of unit costs for combined sodium chloride and calcium carbonate solution, groundwater, and secondary effluent runs are $2.06 - 3.22, $1.98 - 2.57 and $1.56- 2.66 respectively. In this work, unit cost is still higher due to greater energy consumption .by the pumping system which is required in a small-scale RO operation. Based on the experimental results, it appears that the characteristics of feed water samples affect the membrane performance and their effects must be taken into account in the design of RO units so as to reduce the unit cost for water production. / The findings from the present experimental and modelling work are of practical significance in not only providing the knowledge base in the area of desalination but also paves the way for developing tools for the prediction of build-up of solutes on membrane surface in full scale reverse osmosis operations.

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.

Fault diagnosis of sensors, devices, and equipment is an important topic in the nuclear industry for effective and continuous operation of nuclear power plants. All the fault diagnostic approaches depend critically on the sensors that measure important process variables. Whenever a process encounters a fault, the effect of the fault is propagated to some or all the process variables. The ability of the sensor network to detect and isolate failure modes and anomalous conditions is crucial for the effectiveness of a fault detection and isolation (FDI) system. However, the emphasis of most fault diagnostic approaches found in the literature is primarily on the procedures for performing FDI using a given set of sensors. Little attention has been given to actual sensor allocation for achieving the efficient FDI performance. This dissertation presents a graph-based approach that serves as a solution for the optimization of sensor placement to ensure the observability of faults, as well as the fault resolution to a maximum possible extent. This would potentially facilitate an automated sensor allocation procedure. Principal component analysis (PCA), a multivariate data-driven technique, is used to capture the relationships in the data, and to fit a hyper-plane to the data. The fault directions for different fault scenarios are obtained from the prediction errors, and fault isolation is then accomplished using new projections on these fault directions. The effectiveness of the use of an optimal sensor set versus a reduced set for fault detection and isolation is demonstrated using this technique. Among a variety of desalination technologies, the multi-stage flash (MSF) processes contribute substantially to the desalinating capacity in the world. In this dissertation, both steady-state and dynamic simulation models of a MSF desalination plant are developed. The dynamic MSF model is coupled with a previously developed International Reactor Innovative and Secure (IRIS) model in the SIMULINK environment. The developed sensor placement design and fault diagnostic methods are illustrated with application to the coupled nuclear desalination system. The results demonstrate the effectiveness of the newly developed integrated approach to performance monitoring and fault diagnosis with optimized sensor placement for large industrial systems.

El objetivo de ésta tésis fue la caracterización y optimización de una planta piloto EDR IONICS Tipo Aquamite I, con dos etapas eléctricas y seis etapas hidráulicas, buscando las condiciones de funcionamiento para una máxima eficacia del dispositivo.

Esta tesis explica com mejorar la eficiencia del proceso de ultrafiltración en la desalinización de agua de mar. Esto se consigue optimizando diferentes procesos de limpieza como los contralavados y las limpiezas químicas mejoradas. Para conseguirlo se siguen diferentes estrategias como reducir el número de pasos de los contralavados, reducir la frecuencia de los contralavados, usar salmorra proveniente del concentrado de osmosis y reducir el consumo de químicos. Se propone una nueva metodología para analizar los ciclos de limpieza mediante la modelización del proceso. Diferentes tipos de fibra son analizados mediante su permeabilidad y tolerancia a la suciedad. Se presenta una nueva metodología para prevenir la cloración de las membranas de osmosis inversa causadas por las limpiezas químicas mejoradas que se llevan a cabo aguas arriba. Todos los descubrimientos son validados con datos obtenidos de plantas reales. Estas mejoras aumentan la eficiencia del proceso hasta al 98% y reducen el coste de operación de la ultrafiltración en un 7%. / This thesis gives an overview on how to improve efficiency of the ultrafiltration filtration process in seawater desalination. This is achieved by optimizing different cleaning processes such as the backwash and the chemical enhanced backwash. Key success factors rely on reducing the number of backwash steps, improving the backwash frequency, using reverse osmosis brine for backwashing and reducing the chemical consumption. A new methodology to analyze these cleanings cycles is proposed through modeling the process. Different fibers types are also analyzed according to its permeability and its fouling tolerance. A methodology to prevent reverse osmosis chlorination from upstream chemical enhanced backwash cleaning is presented. All the findings are validated through real plant operating data. The proposed improvements increase the process efficiency to 98% and lead to a 7% cost reduction in the ultrafiltration process.