Dissertations / Theses on the topic 'Continuous reactors'

Garlic secondary metabolites are organosulfur compounds that possess prophylactic properties. The chemical composition of garlic oil extracts consists of a combination of these compounds. The instability of a major component, allicin 5, limits the commercial viability of garlic oil extracts. The synthesis of garlics organosulfur compounds has been performed in batch reactors. In this thesis, flow reactors were utilised to improve the throughput, reduce the operating conditions. The thermolysis of allicin 5 is the solitary approach to produce the garlic metabolite, ajoene 14. Ajoene 14 has greater stability compared to allicin 5 that possesses interesting biological activity. The primary three-step synthesis investigated consisted of dialkyl polysulfide synthesis, subsequent oxidation and finally the terminal thermolysis. In addition, other garlic metabolites have also been produced. The synthesis of unsymmetrical monosulfides and their subsequent oxidation was investigated using novel heterogeneous packed-bed flow reactors. The stable amino acid, alliin 15, is the precursor of allicin 5. Alliin 15 was also synthesised in homogeneous flow mode. The telescoped synthesis of alliin 15 was successfully completed using a semi-batch reactor. Development of novel approaches to synthesise garlics organosulfur compounds is reported in this thesis. Finally, the flow reactor systems, experimental details and characterisation of the compounds are described.

<p> The control of pH is one of the most difficult chemical control schemes in industry. Often, large tanks are used to control pH. The pH in these large tanks frequently overshoots the desired pH set-point and usually takes a long time to reach the desired set-point. In this work, a conceptual pH control process was developed and tested by using two small continuous stirred tank reactors (CSTRs). In this two-step system, the bulk of the neutralization is carried out in the first reactor and then fine-tuned in the second reactor. The conceptual neutralization model was built by analyzing the chemistry behind pH. Because pH is a nonlinear function of hydrogen ion concentration (pH= -log [H⁺]), the hydrogen ion concentration was chosen as the process measured variable. The slope (Gain) was calculated from a titration curve obtained from a polynomial derived from neutralization chemistry and a practical titration. The process dynamics were then fitted into the classic proportional, integral, and differential (PID) controller using the Internal Model Control (IMC) tuning method. The robust tuning parameters produced by the IMC method were able to bring the pH in the first CSTR to the desired set-point. In addition, disturbances from vibrations produced by the pump and magnetic stirrer, slight variations in reactant concentration, and pH probe lags were easily eliminated. Most importantly, pH in the second CSTR settled on the desired neutral set-point of pH 7.0 after brief oscillations. The process was repeatable when the reactors where scaled up one hundred times using synthetic waste water. Autotune variation results produced similar process dynamics to those produced by calculating the slope from the titration curve. </p>

The polymerase chain reaction (PCR) is an enzyme catalyzed technique, used to amplify the number of copies of a specific region of DNA. This technique can be used to identify, with high-probability, disease-causing viruses and/or bacteria, the identity of a deceased person, or a criminal suspect. Even though PCR has had a tremendous impact in clinical diagnostics, medical sciences and forensics, the technique presents several drawbacks. For example, the costs associated with each reaction are high and the reaction is prone to contamination due to its inherent efficiency and high sensitivity. By employing microfluidic systems to perform PCR these advantages can be circumvented. This thesis addresses implementation issues that adversely affect PCR in microdevices and aims to improve the efficiency of the reaction by introducing novel materials and methods to existing protocols. Molecule-surface-interactions and temperature control/determination are the main focus within this work. Microchannels and microreactors are characterized by extremely high surface-to-volume ratios. This dictates that surfaces play a dominant role in defining the efficiency of PCR (and other synthetic processes) through increased molecule-surface interactions. In a multicomponent reaction system where the concentration of several components needs to be maintained the situation is particularly complicated. For example, inhibition of PCR is commonly observed due to polymerase adsorption on channel walls. Within this work a number of different surface treatments have been investigated with a view to minimizing adsorption effects on microfluidic channels. In addition, novel studies introducing the use of superhydrophobic coatings on microfluidic channels are presented. Specifically superhydrophobic surfaces exhibiting contact angles in excess of 1500 have been created by growing copper oxide and zinc oxide nanoneedles and silica-sol gel micropores on microfluidic channels. Such surfaces utilize additional surface roughness to promote hydrophobicity. Aqueous solutions in contact with superhydrophobic surfaces are suspended by bridging-type wetting, and therefore the fraction of the surface in contact with the aqueous layer is significantly lower than for a flat surface. An additional difficulty associated with PCR on microscale is the detennination and control of temperature. When perfonning PCR, the ability to accurately control system temperatures is especially important since both primer annealing to single-stranded DNA and the catalytic extension of this primer to form the complementary strand will only proceed in an efficient manner within relatively narrow temperature ranges. It is therefore imperative to be able to accurately monitor the temperature distributions in such microfluidic channels. In this thesis, fluorescence lifetime imaging (FLIM) is used as a novel method to directly quantify temperature within microchannel environments. The approach, which includes the use of multiphoton excitation to achieve optical sectioning, allows for high spatial and temporal resolution, operates over a wide temperature range and can be used to rapidly quantify local temperatures with high precision.

The aim of this work was to design novel reactors to increase the reaction conversion and enantioselectivity for the asymmetric transfer hydrogenation (ATH) of acetophenone. The reactor designs should also be amenable to scale-out for increase of productivity. Asymmetric transfer hydrogenation of acetophenone with isopropanol is a reversible reaction and backwards reaction limits the reaction conversion and enantioslectivity. Novel reactor design aims to efficient acetone removal, which is a byproduct in the reaction system. By gas stripping, reaction equilibrium can be shifted and hence conversion and enantioselectivity improved. Reaction conditions optimization was initially conducted in a laboratory batch reactor and a simple kinetic model was built. The catalyst deactivation, the effect of the temperature, substrate concentration, substrate/catalyst concentration ratio and acetone concentration on the ATH were investigated. The metal-ligand bifunctional mechanism was considered for the kinetic model. The gPROMS/gEST commercial software was used for kinetic parameters estimation. Three continuous reactors (tubular reactor, rotating disc reactor and micromesh reactor) were designed and fabricated, each one encompassing a different gas/liquid contacting method. In the tubular reactor, gas/liquid contact is achieved through slugs. In the rotating disc reactor, gas/liquid contact is achieved through a thin film formed on the disc which rotates. In the micromesh reactor, a micromesh forms and stabilizes the gas/liquid interface. Acetone removal and asymmetric transfer hydrogenation studies were carried out under different conditions in these reactors and the performance of the different reactors were compared. The tubular reactor showed similar performance as the batch reactor. The rotating disc reactor enhanced acetone removal, thus improved the conversion and enantioselectivity. Acetone was removed most efficiently in the micromesh reactor. Therefore, the highest conversion and enantioslectivity were also obtained in this reactor. By simplified calculations, it was established that in order to increase the acetone removal efficiency, the ratio of gas to liquid flowrate and the gas-liquid interfacial area has to be increased. The scale out/up concept was also demonstrated with the micromesh reactor. Scale out/up was achieved by increasing the number of meshes in parallel and enlarging the single mesh reactor. The conversion and enantioselectivity was slightly lower in the scaled out version reactor which is probably due to the fact that the flow distribution inside the reactor was not uniform.

Effective treatment of wastewater is an important process in reducing the environmental impact of industry and human activity. Although conventional water treatment systems can adequately remove the principle components of waste (i.e. substances that can be represented the majority of biological and chemical oxygen demand) several materials are poorly or slowly removed. Tertiary treatment polishing processes are therefore required to remove these contaminants to ensure complete wastewater treatment. This thesis reports investigations made using film reactors that are used to remove recalcitrant materials such as ammonia- nitrogen and endocrine disrupters that although present in low concentrations, if left untreated can have a strong impact on the environment. Film reactors potentially offer several process advantages over conventional activated sludge treatments systems as they allow very long residence time and contact with high concentrations of fixed microbes with the low concentrations of pollutants so enhancing kinetic performance and efficiency of the process. Two reactor configurations, a partial fixed bed (PFBR) and moving bed biofilm reactors (MBBR) were investigated. A thirty liter reactor with a working volume of 16 liters was constructed and contained fixed microbial films on either free suspended or fixed beds plastic packing (K2 AnoxKaldnes). The investigation of ammonia-nitrogen oxidation showed that after a suitable acclimation period (2 weeks) that ammonia was oxidise rapidly reducing the feed concentrations of 35 mg/L to < 2 mg/L in the effluent. To assess the performance for ammonia-nitrogen removal the reactors operated for long periods (up to 3 months) with continuous feed using the reactor in either PFBR or MBBR modes in addition of 17alpha-ethynylestradiol (EE2) and mestranol (MeEE2), the endocrine disrupting compounds commonly found in municipal wastewater. These substances is derived from a synthetic hormones if found in the natural environment can reduced the productivity of the fish as this can cause feminization in aquatic organisms with disastrous consequences on fish populations. The MBBR and PFBR systems were used to investigate the co-metabolism of ammonia-nitrogen, 17alpha-ethynylestradiol (EE2) and mestranol from model waste water feed containing 35 mg/L of ammonia-nitrogen and 100 mug/L of 17alpha-ethynylestradiol (EE2) and mestranol (MeEE2). A kinetic analysis of the systems were made and for the PFBR reactor, the specific growth rate, mumax of 7.092 d-1 with saturation constants, Ks of 1.574 mg/L. The kinetic analysis for the MBBR system was 6.329 d-1 for the mumax with the K.S of 0.652 mg/L. When the PFBR was used removal of EE2 represents 70% MeEE2 was removed. MBBR were shown to be more effective and efficient in removing ammonia-nitrogen reducing the levels under good conditions to > 2 mg/L while the PFBR could also achieve 2 mg/L. The MBBR system was also more competent in the removal of 17alpha-ethynylestradiol (EE2) and mestranol compared to PFBR. This work demonstrates that there are considerable advantages to using thin film reactors as polishing step for the tertiary treatment of waste waters when to compared to other processes in reducing the inorganic pollutants as endocrine disrupting compounds. The significance of these results is discussed in this context.

One of the most important boron minerals, colemanite is reacted with sulfuric acid to produce boric acid. During this reaction, gypsum (calcium sulfate dihydrate) is formed as a byproduct. In this study, the boric acid production was handled both in a batch and four continuously stirred slurry reactors (4-CFSSR&rsquo<br>s) in series system. In this reaction system there are at least three phases, one liquid and two solid phases (colemanite and gypsum). In a batch reactor all the phases have the same operating time (residence time), whereas in a continuous reactor all the phases may have different residence time distributions. The residence time of both the reactant and the product solids are very important because they affect the dissolution conversion of colemanite and the growth of gypsum crystals. The main aim of this study was to investigate the dynamic behavior of continuous flow stirred slurry reactors. By obtaining the residence time distribution of the solid and liquid components, the non-idealities in the reactors can be found. The experiments performed in the continuous flow stirred slurry reactors showed that the reactors to be used during the boric acid production experiments approached an ideal CSTR in the range of the stirring rate (500-750 rpm) studied. The steady state performance of the continuous flow stirred slurry reactors (CFSSR&rsquo<br>s) in series was also studied. During the studies, two colemanites having the same origin but different compositions and particle sizes were used. The boric acid production reaction consists of two simultaneous reactions, dissolution of colemanite and crystallization of gypsum. The dissolution of colemanite and the gypsum formation was followed from the boric acid and calcium ion concentrations, respectively. The effect of initial CaO/ SO42- molar ratio (1.00, 1.37 and 2.17) on the boric acid and calcium ion concentrations were searched. Also, at these initial molar ratios the colemanite feed rate was varied (5, 7.5, 10 and 15 g/min) to change the residence time of the slurry. Purity of the boric acid solution was examined in terms of the selected impurities, which were the magnesium and sulfate ion concentrations. The concentrations of them were compared at the initial molar ratios of 1.00 and 1.37 with varying colemanite feed rates. It was seen that at high initial CaO/ SO42- molar ratios the sulfate and magnesium ion concentrations decreased but the calcium ion concentration increased. The gypsum crystals formed in the reaction are in the shape of thin needles. These crystals, mixed with the insolubles coming from the mineral, are removed from the boric acid slurry by filtration. Filtration of gypsum crystals has an important role in boric acid production reaction because it affects the efficiency, purity and crystallization of boric acid. These crystals must grow to an appropriate size in the reactor. The growth process of gypsum crystals should be synchronized with the dissolution reaction. The effect of solid hold-up (0.04&ndash<br>0.09), defined as the volume of solid to the total volume, on the residence time of gypsum crystals was investigated and the change of the residence time (17-60 min) on the growth of the gypsum was searched. The residence time at each reactor was kept constant in each experiment as the volumes of the reactors were equal. The growth of gypsum was examined by a laser diffraction particle size analyzer and the volume weighted mean diameters of the gypsum crystals were obtained. The views of the crystals were taken under a light microscope. It was observed that the high residence time had a positive effect on the growth of gypsum crystals. The crystals had volume weighted mean diameters of even 240 &micro<br>m. The gypsum crystal growth model was obtained by using the second order crystallization reaction rate equation. The residence time of the continuous reactors are used together with the gypsum growth model to simulate the continuous boric acid reactors with macrofluid and microfluid models. The selected residence times (20-240 min) were modeled for different number of CSTR&rsquo<br>s (1-8) and the PFR. The simulated models were, then verified with the experimental data. The experimentally found calcium ion concentrations checked with the concentrations found from the microfluid model. It was also calculated that the experimental data fitted the microfluid model with a deviation of 4-7%.

Thesis (M.S.) -- University of Maryland, College Park, 2004.<br>Thesis research directed by: Dept. of Chemical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

The rapidly increasing prices of petroleum fuels and potential shortages, have created a need for renewable fuels derived from organic waste products. The objective of this research project is to produce advanced multipurpose, continuous microwave biofuelslchemical reactors to utilise waste vegetable oils. The heat transfer efficiency of the reactor was studied using pure vegetable oils to establish the reactor design, operating temperatures and controls necessary to produce First Generation biodiesel by advanced microwave technology. Water modelling was used to scale up the reactors from 200 W to 1.2 kW and then subsequently to 2 kW. Once the initial continuous reactor was optimised, the work was repeated using various grades of waste cooking oils provided by Longma Clean Energy Ltd. In order to achieve the required conversion to give 96.5% methyl esters, these oils needed larger quantities of both catalyst and methanol to reduce the viscosity of the crude oil. The system was then modified to carry out microwave assisted methanol extraction of free fatty acids, with the addition of a decanter to allow continuous phase separation. This process produced no glycerol, was energy efficient and the free fatty acids that were removed, were recovered in the methanol distillation unit. In the future, the waste frictional heat from the diesel engine could be used to grow algae, the waste heat from the exhaust gases could be used to heat the distillation unit and the carbon dioxide could be biofixated by microalgae. An industrial prototype 1.2 kW microwave de-acidification unit has now been built at the Longma Clean Energy site at Hereford. There is a surplus of poor quality biodiesel glycerol that is currently regarded as a waste product. The novel continuous microwave unit which was developed from the biodiesel reactor has been used to acetyl ate the glycerol with acetone at below 50°C to produce acetals for use as fuel additives. An atmospheric/vacuum fractional distillation column will be required to recover the methanol or acetone and to distil the acetal from the unreacted glycerol, which is then recycled. The technology developed can utilise any waste cooking oils, acidic seed oils or fats as biofuels for combined heat and power generation or to convert them to biodiesel fuels. This research work is the basis of an integrated, green, low carbon, microwave based refinery. 2

Includes abstract.<br>Includes bibliographical references (p. 84-87).<br>Fischer Tropsch Synthesis (FTS) is the conversion of syngas (CO and H2) to cleaner liquid transportation fuels. The modelling of such a supercritical, highly non-ideal, multi-component system requires the detailed knowledge of the reaction mechanism, reaction kinetics, phase-equilibrium and reactor technology. The objectives of this work were to: develop a complete Fischer Tropsch model, predict the hydrocarbon product distribution, determine what effect Vapour-Liquid Equilibrium (VLE) has on the product distribution, selectivity and kinetics, and determine whether the deviations from the 'ideal' Anderson-Schulz Flory (ASF) distribution can be attributed to VLE.

A suboptimal controller has been developed for a Boiling Water Reactor Nuclear Power Plant, using the DARE P Continuous Simulation Language, which was developed in the Electrical Engineering Department at the University of Arizona. A set of 48 nonlinear first-order differential equations and a large number of algebraic equations has been linearized about the equilibrium state. Using partitioning, the linearized equations were transformed into a block triangular form. The concept of optimal control and a square performance index reflecting the desired plant behavior have been applied on the slow subsystem to develop a suboptimal controller. The obtained feedback law is shown by simulation to be able to compensate for a variety of plant disturbances. A large variety of responses can be obtained by changing the weighting matrices. The control is basically a regulator approach to speed up response during load demand changes. Several simulations are included to demonstrate the control performance. The variables to be controlled have mainly been the average neutron density and the average coolant temperature. Simplifications have been suggested, thus obtaining considerable savings in the computations and ease in design.

Biocatalytic membranes (BMs) have promising applications in a diversity of fields including food, pharmaceutical and water treatment industries. Of particular relevance, Alcalase is a commercially important protease that has been applied for the production of peptides from the hydrolysis of proteins. In this study, two different approaches were applied for the modification of electrospun polyacrylonitrile nanofibrous membranes (EPNMs) for Alcalase immobilization. The first approach is alkali modification of EPNMs followed by EDC/NHS coupling for covalent bonding with Alcalase, whereas the other is based on polydopamine coating with or without glutaraldehyde grafting as a covalent linker. Immobilized Alcalase on these prepared BMs were studied and compared with free enzymes. It was found that the stabilities of Alcalase on BMs created using both approaches were improved, which enabled their reuse of 10 cycles with significant retention of enzymatic activity. A continuous reactor housing BMs were tested for hydrolysis of both model substrate, azo-casein and soybean meal protein (SMP). It was found that decreasing flux could improve the extent of hydrolysis and that a single-layer reactor can hydrolyze about 50% of the substrate to peptides with the molecular weight of 10 kDa or less. Hydrolysis of SMPs was demonstrated in a continuous five-layer BM reactor and both BMs showed excellent hydrolysis capacity. This study provides the groundwork for the development of high-efficiency BM for continuous and cost-effective protein hydrolysis for the production of value-added peptides.

This study has developed a new empirical substrate removal model for continuous flow stirred tank reactor (CFSTR) and sequencing batch reactor (SBR) systems. In this model, an exponential function of volatile suspended solids (VSS) was introduced to express active biomass in substrate utilization kinetics. The proposed empirical substrate removal model is expressed as: dS/dt = $\rm -K\sp\prime X\sb{v}\sp{n}S.$ The kinetic constants K$\sp\prime$ and n in the model were estimated from batch tests. Then, this model was validated for CFSTR and SBR continuous flow systems. The results obtained from batch tests, conducted with sludge from the CFSTR and SBR systems, showed that the exponential model can more accurately express the substrate removal rate in a batch reactor than the conventional first order equation. A comparison of the new exponential and the first order model indicates that the exponential model can more accurately predict the effluent COD concentrations for both CFSTR and SBR continuous flow systems. The first order rate constants (K) for both CFSTR and SBR systems were affected by the reactor sludge age, the influent COD and the biomass concentrations. The kinetic constants K, yield factor (Y), and endogenous decay coefficient $\rm (k\sb{d})$ obtained for SBR system were higher than those for CFSTR. The statistical analysis results indicated that SBR system performed at a higher substrate removal efficiency compared to the CFSTR. Also the sludge grown in the SBR reactors had a better settleability than that produced in the CFSTR. The optimal organic loadings for controlling sludge bulking in the CFSTR and SBR were found to be less than 0.7 mg COD/mg VSS/d and 1.2 mg COD/mg VSS/d, respectively. In addition, the SBR reactor could be operated at an F/M ratio of 1.4 mg COD/mg VSS/d, which was twice the F/M ratio in the CFSTR without a significant decrease in treatment efficiency.

The prevalence of chiral amines in pharmaceutical compounds means that efficient synthetic methods are highly desirable. Asymmetric catalysis offers the opportunity for enantioselective synthesis of chiral amines under milder reaction conditions. Chemical and biological catalysts both offer specific advantages and disadvantages that are different to the other catalyst type. Therefore, the combination of catalysts would allow for the advantages of each to be exploited, whilst overcoming the associated disadvantages. This research investigates the combination of chemical and biological catalysts for the production of chiral amines and essential medicines using continuous reactors. Continuous reactors are increasingly seen as a method to improve synthesis routes due to their improved productivity and safety compared to batch reactors. In addition to continuous reactors, immobilised catalysts and design of experiments (DoE) strategies were employed for the development of optimised procedures. Firstly, the enzymatic kinetic resolution of a chiral primary amine was studied in a continuous packed bed reactor (PBR) using an immobilised lipase enzyme. Optimum reaction conditions were determined using a one variable at a time (OVAT) approach to give the maximum 50% conversion with high product ee in only a 6 min residence time (tRes). The PBR system was then applied to an expanded substrate set, including chiral amines and alcohols, to act as a comparison to the standard amine. Secondly, metal catalysed racemisation was investigated as a method to utilise the waste enantiomer from the enzymatic resolution in a dynamic kinetic resolution process (DKR). Homogeneous and heterogeneous Ir, Ru and Pd catalysts were tested for the amine racemisation step. However, the amount of racemisation observed was not sufficient and uncontrolled dimerisation primarily occurred. Next, the enzymatic PBR was applied to the production of essential medicines via enzymatic ammoniolysis. The development of cheaper more efficient methods to produce essential medicines is vital to make them more affordable and accessible to the developing world. In this instance, the reaction conditions were optimised using DoE with the objective being to maximise conversion. Nicotinamide and pyrazinamide were produced in 94% and 100% yields with a tRes of 60 min and 20 min, respectively. The ammoniolysis of a chiral substrate was also tested; however, this was not successful using the experimental conditions described. Finally, metal catalysed N-alkylation using Ir was investigated for the N-alkylation of the chiral primary amine as an alternative method to utilise the waste enantiomer from the continuous resolution. DoE and microwave heating techniques were employed to optimise the reaction conditions and reduce the amount of waste associated with development. In this example, the formation of un-desired dimeric products was problematic and so the optimisation objectives were both maximum conversion and maximum selectivity for the desired product. Overall, the transferal of processes into continuous PBR and optimisation techniques allowed for the intensification of reaction conditions, which led to more productive, efficient routes. However, the difficulties in combining chemical and biological catalysts were also highlighted when the combination of reactions was attempted.

Le furfural, identifié comme l'un des 30 principaux produits chimiques biologiques, est une molécule importante en terme de chimie verte et développement durable. L'objectif de ce travail de doctorat est de réaliser la synthèse et la conversion du furfural en flux continu et par lots. Ici, nous avons développé des méthodes plus éco-efficiente pour la synthèse du furfural, et valorisé le furfural en produits à haute valeur ajoutée, tels que le 2-furonitrile, l'alcool furfurylique, etc... Plusieurs questions clés ont été identifiées afin de concevoir des processus plus écologiques que les processus actuels. En détail, des expériences de synthèse du furfural ont été réalisées dans l'eau pure ou dans un mélange eau-solvants organiques lorsque des co-solvants (verts ou écologiques) sont nécessaires. L'irradiation par micro-ondes a été choisie comme méthode de chauffage pour accélérer le processus de déshydratation, et un réacteur à flux continu à micro-ondes a également été utilisé pour améliorer la productivité du furfural. En partant du furfural pour produire des produits chimiques à haute valeur ajoutée, des réacteurs à flux efficace, tels que Pheonix, H-cube Pro ainsi que des micro-ondes à flux continu avec micro-réacteur, ont également été identifiés comme des alternatives intéressantes pour améliorer la productivité des composés cibles. En conséquence, certains résultats prometteurs ont été obtenus du point de vue de l'industrie<br>Furfural, which has been identified as one of top 30 bio-based chemicals, is an important green platform molecule, The aim of this PhD work is to realize the synthesis and conversion of furfural in batch and continuous flow. Here, we developed sorne greener methods for furfural synthesis, and valorized furfural into high value-added products, such as 2-furonitrile, furfuryl alcohol etc. Several keys issues were identified in order to design processes greener than the current ones. ln detail, experiments for furfural synthesis were performed in water or in water and organic solvent when co-solvents (green or eco-friendly) are necessary. Microwave irradiation has been chosen as the heating method to accelerate the dehydration process, and microwave continuous flow reactor was also applied to improve furfural productivity. When starting from furfural to produce high value-added chemicals, efficient flow reactors, suc as Pheonix, H-cube Pro as well as microwave continuous flow With micro-reactor, were also identified as interesting alternatives to improve the productivities of target compounds. As a result, some promising results were obtained in the viewpoint of industry

Due to their small particle size, nanoparticles ( < 100 nm in diameter) have an increased surface area to volume ratio compared to larger particles, meaning that surface attributes become increasingly important over bulk properties. Chemically, this means more atoms in the material have unsatisfied coordination environments compared to atoms in the bulk of the particle. In many cases, this leads to materials with significantly different bulk properties compared to much larger particles; some of these unique properties are desirable in high technology applications such as sun screens, catalysts, etc. This thesis explores the use of Continuous Hydrothermal Flow Synthesis (CHFS) reactors as a niche technology to controllably produce nanoparticles at different process scales. In CHFS, a metal ion feed is mixed with superheated water (the latter is typically above the critical temperature and pressure of water, i.e. 374 °C, 22.1 MPa), and nanoparticles are precipitated. This thesis presents data relevant to an evaluation of a laboratory scale CHFS process (able to produce ca. 100 g a day of nanoparticles). This included the development of a new type of mixer for this type of process suitable for the continuous precipitation of nanoparticles. The knowledge gained from in situ measurements and particle property measurements was then applied to the successful scale up of the technology to produce up to ca. 2 kg per hour of nanoparticles. It was demonstrated that the versatility of a flow process and the rapid crystallising environment in a CHFS system could be effectively exploited for the production of target nanoparticles when appropriate synthesis conditions were used. This thesis has also demonstrated the versatility of CHFS in that as formed particles could be surface functionalised in flow by use of an additional feed in process. The outcomes of this thesis have been demonstrated using a variety of material compositions; Hydroxyapatite, ZnO, iron oxides, yttrium oxyhydroxide, yttrium oxide and the binary oxide series Ce-Zn. Where each material composition was used to probe different aspect of the continuous hydrothermal process reported in this work. In summary, the CHFS process has been evaluated and developed to allow for synthesis of a wide range of nanoparticle compositions with different particle properties. Process modifications have been evaluated and shown to be suitable for the synthesis of target materials.

This research is dedicated to develop a fully integrated system for heavy metals determination in water samples based on micro fluidic plasma atomizers. Several configurations of dielectric barrier discharge (DBD) atomizer are designed, fabricated and tested toward this target. Finally, a combination of annular and rectangular DBD atomizers has been utilized to develop a scheme for heavy metals determination. The present thesis has combined both theoretical and experimental investigations to fulfil the requirements. Several mathematical studies are implemented to explore the optimal design parameters for best system performance. On the other hand, expanded experimental explorations are conducted to assess the proposed operational approaches. The experiments were designed according to a central composite rotatable design; hence, an empirical model has been produced for each studied case. Moreover, several statistical approaches are adopted to analyse the system performance and to deduce the optimal operational parameters. The introduction of the examined analyte to the plasma atomizer has been achieved by applying chemical schemes, where the element in the sample has been derivitized by using different kinds of reducing agents to produce vapour species (e.g. hydrides) for a group of nine elements examined in this research individually and simultaneously. Moreover, other derivatization schemes based on photochemical vapour generation assisted by ultrasound irradiation are also investigated. Generally speaking, the detection limits achieved in this research for the examined set of elements (by applying hydroborate scheme) are found to be acceptable in accordance with the standard limits in drinking water. The results of copper compared with the data from other technologies in the literature, showed a competitive detection limit obtained from applying the developed scheme, with an advantage of conducting simultaneous, fully automated, insitu, online- real time analysis as well as a possibility of connecting the proposed device to control loops.

Esta tesis doctoral versa sobre la eliminación simultánea de compuestos fenólicos con reactores de biomasa granular trabajando en continuo. El estudio está dividido en dos partes principales; el primer tema trata sobre la modelización de la nitritación, mientras que el otro está dedicado al trabajo experimental sobre la nitritación y eliminación simultánea de compuestos fenólicos. En el estudio de modelización, se desarrolló un modelo matemático de biopelícula para describir la nitritación en reactores de biomasa granular aerobia operando en continuo. El modelo incorpora una estrategia de control del ratio [DO]/[TAN], para mantener un valor deseado de la relación entre las concentraciones de oxígeno disuelto (DO) en el efluente del reactor y nitrógeno amoniacal total [TAN]. El modelo se validó con un gran número de datos experimentales previamente publicados en la bibliografía, así como con datos obtenidos de reactores granulares tratando agua de rechazo a escala laboratorio y piloto. El modelo se utilizó para estudiar el efecto de: a) las consignas de DO y TAN, b) la temperatura de operación, c) las características de la biopelícula (tamaño de partícula, densidad) y d) la concentración de amonio en el afluente, sobre la consecución de la nitritación completa. Los resultados indicaron que la nitritación completa se mantuvo estable y se potenció usando la estrategia de control de la proporción [DO]/[TAN] en la operación del reactor de biomasa granular aerobia. Además, el modelo predijo que gránulos aerobios mayores a 1.5 mm y concentraciones altas de amonio en el afluente potenciaba la obtención de nitritación completa estable, mientras que la densidad de biopelículas tenía poca influencia en este estudio. Además se demostró que era posible la nitritación total a bajas temperaturas con reactores de biomasa granular. Para el trabajo experimental, se utilizó un reactor tipo airlift. Para la puesta en marcha del reactor, se utilizó como inóculo biomasa de un reactor de biomasa granular aerobia que realizaba eliminación de nutrientes. Como alimento del reactor se utilizó un agua residual sintética con un alto contenido de amonio (950 ± 25 mg N L-1). El reactor se operó hasta la obtención de nitritación parcial. Una vez obtenida la nitritación parcial, el reactor se bioaumentó con un lodo activo que contenía biomasa degradadora de p-nitrofenol (PNP) para mejorar el crecimiento de microorganismos degradadores de fenol sobre los gránulos nitrificantes. Acto seguido, mientras el reactor trataba una carga elevada de amonio, se añadieron progresivamente al afluente o-cresol (hasta 100 mg L-1) o PNP (hasta 15 mg L-1), siendo éstos alimentados al reactor con el objetivo de estudiar la nitritación parcial simultánea a la eliminación de o-cresol o de PNP. En el estudio de la nitritación parcial simultánea a la eliminación de o-cresol, se mantuvo el proceso de nitritación parcial estable durante más de 100 días de operación. Además, se obtuvo una biodegradación completa de o-cresol durante todo el periodo experimental. También se realizaron choques de carga de o-cresol, durante los cuales el proceso de nitritación parcial se mantuvo estable y sin verse afectado por esos eventos. Las cargas volumétricas obtenidas de nitrógeno (NLRV) y de o-cresol (CLRV) fueron de 1.1 g N L-1 d-1 y 0.11 g o-cresol L-1 d-1, respectivamente. El análisis de hibridación in situ de fluorescencia (FISH) indicó que en los gránulos había presencia del género Acinetobacter, de bacterias amonio-oxidantes betaproteobacteriales y de Nitrobacter sp. Posteriormente, se continuó con la operación del reactor, y se llevó a cabo un experimento relacionado con el funcionamiento del reactor bajo tres escenarios de alternancia secuencial de contaminantes (SAP). En cada uno de los escenarios SAP se añadieron 15 mg L-1 de compuestos fenólicos secundarios (i.e. PNP, fenol y 2-clorofenol (2CP)) al afluente por un periodo de tiempo corto (entre 20 y 25 años). Los resultados ilustraron que se mantuvo la nitritación parcial y la biodegradación de o-cresol sin mostrar ningún signo de inhibición por la presencia de PNP o de fenol. Sin embargo, en presencia de 2CP en el afluente, se registró durante tres días un 90% de la nitritación parcial y un 25% de la degradación de o-cresol. Estos resultados sugieren que las bacterias amonio oxidantes (AOB) son mas sensibles a la inhibición por 2CP que las heterótrofas (degradadoras de o-cresol). En el estudio de la nitritación simultánea a la eliminación de PNP, se mantuvo la nitritación durante la mayor parte del periodo operacional, obteniéndose un efluente adecuado para la desnitrificación heterotrófica. Sin embargo, durante los primeros 175 días, la biodegradación de PNP fue inestable, observándose diversos episodios de acumulación de PNP. Esta acumulación se determinó que era debida a las condiciones limitantes de DO. El incremento de la concentración de DO en el reactor de 2 a 4 mg O2 L-1 permitió obtener eliminación completa y estable de PNP hasta el fin del periodo experimental. Las NLRV y la carga de PNP obtenidas fueron de 1.0 g N L-1 d-1 y 16 mg PNP L-1 d-1, respectivamente. Además, se evaluó el funcionamiento del reactor realizando dos estudios de hambruna, i) hambruna de PNP y ii) hambruna total (parada del reactor). Los resultados mostraron que 2 días después al fin del periodo de hambruna se obtuvo una recuperación total de la degradación de PNP, mientas que la recuperación total de la nitritación simultánea a la eliminación de PNP se consiguió solo 11 después de volver a poner en marcha el reactor. En conclusión, el uso de reactores de biomasa granular aerobia para realizar nitritación simultánea a la eliminación de compuestos fenólicos es factible. Ésta podría ser considerada la mejor técnica disponible para el tratamiento aguas residuales industriales complejas con contenido de amonio en alta carga y compuestos fenólicos. Se ha probado que la biomasa granular aerobia es resistente a sobrecargas puntuales, a presencia alterna de compuestos recalcitrantes y a periodos de hambruna; estas condiciones, debido a los cambios de planificación de la producción, pueden encontrarse frecuentemente en plantas de tratamiento de aguas residuales industriales. En un futuro próximo, proponemos que la nitritación simultánea a la eliminación de compuestos fenólicos podría combinarse tanto con la desnitrificación heterotrófica o con el proceso anammox para una eliminación sostenible del nitrógeno.<br>The simultaneous nitritation and phenolic compounds removal using aerobic granular reactors in continuous mode were studied in this Ph.D. thesis. The study is divided into two main subjects; the first one is devoted to the modeling of nitritation while the other part is dedicated to the experimental work of simultaneous nitritation and phenolic compounds removal using granular reactors. In the modeling study, a mathematical biofilm model was developed to describe nitritation in aerobic granular reactors operating in continuous mode. The model incorporated a [DO]/[TAN] ratio control strategy to maintain the proportion between the concentrations of dissolved oxygen (DO) and total ammonia nitrogen (TAN) in the reactor effluent to a desired value. The model was validated with a large set of experimental results previously reported in the literature, as well as, data gathered from laboratory scale and pilot plant granular reactors treating reject water. The model was used to study the effect of: a) DO and TAN setpoints, b) operating temperature, c) biofilm characteristics (granules size, density) and d) ammonium concentrations in the influent on the achievement of full nitritation. The results indicated that full nitritation was stably maintained and enhanced by applying the [DO]/[TAN] ratio control strategy in the operation of aerobic granular sludge reactor. Moreover, the model predicted that aerobic granules size larger than 1.5 mm and high ammonium concentrations in the influent enhanced the achievement of stable full nitritation, while poor influence of the biofilm density was found with the simulation study. Furthermore, at low temperature, full nitritation with granular reactors was demonstrated to be possible. In the experimental work, an airlift reactor was employed. In the reactor start-up, granular sludge from a reactor performing biological nutrient removal was used as inoculum. A synthetic wastewater containing high-strength ammonium concentrations (950 ± 25 mg N L- 1) was fed into the airlift reactor. The reactor was operated until partial nitritation was obtained. Once partial nitritation was achieved, the airlift reactor was bioaugmented with pnitrophenol (PNP)-degrading activated sludge to enhance the growth of phenolic-degraders over the nitrifying granules. Immediately, o-cresol (up to 100 mg L-1) or PNP (up to 15 mg L- 1) were progressively added to the high-strength ammonium influent and fed into the reactor with the objective of studying the simultaneous partial nitritation and o-cresol removal and the simultaneous nitritation and (PNP) removal. First, in the study of simultaneous partial nitritation and o-cresol removal, a stably partial nitritation process was maintained for more than 100 days of operation. Moreover, full biodegradation of o-cresol was achieved during the whole experimental period. Also, o-cresol shock load events were applied and the partial nitritation process was kept stable and unaffected during these events. The achievable nitrogen loading rate (NLRv) and o-cresol loading rate (CLRv) were ca. 1.1 g N L-1d-1 and 0.11 g o-cresol L-1d-1, respectively. Analysis of fluorescent in-situ hybridization (FISH) indicated that Acinetobacter genus, betaproteobacterial ammonia-oxidizing bacteria and Nitrobacter sp. were present into the granules. Later, the operation of the reactor was continued, and an experiment devoted to the performance of the reactor under three sequentially alternating pollutant (SAP) scenarios was executed. In each one of the SAP scenarios, 15 mg L-1 of the secondary phenolic compounds (i.e. p-nitrophenol (PNP), phenol and 2-chlorophenol (2CP)) were added in the regular influent for a short period of time (between 20 to 25 days). The results illustrated that partial nitritation and o-cresol biodegradation were maintained without exhibiting any sign of inhibition by the presence of PNP or phenol. However, when 2CP was present in the influent, 90 % of the partial nitritation and 25 % of the o-cresol degradation was inhibited within three days. This finding suggests that the ammonia oxidizing bacteria (AOB) is more sensitive to 2CP inhibition than heterotrophs (o-cresol-degraders). Second, in the study of simultaneous nitritation and PNP removal, nitritation was maintained during most of the operation period producing an effluent suitable for heterotrophic denitrification. However, in the first 175 days, PNP biodegradation was unstable and several accumulation episodes occurred. The oxygen limiting condition was found to be the main explanation of these events. The increase of dissolved oxygen concentration (DO) in the reactor from 2 to 4 mg O2 L-1 permitted to achieve complete and stable PNP removal till the end of the experimental period. The achieved NLRv and PNP loading rate (PNP-LRv) were ca. 1.0 g N L-1d-1 and 16 mg PNP L-1d-1, respectively. Besides, the performance of the reactor was further assessed by performing two starvation studies, i) PNP starvation and ii) total starvation period (reactor shutdown). Results show that full recovery of PNP degradation was achieved within 2 days after the PNP starvation period ended, while full recovery of simultaneous nitritation and PNP removal was accomplished in just 11 days after the restart of the reactor. In conclusion, the use of continuous aerobic granular reactors for the simultaneous nitritation and phenolic compounds removal is feasible. This could be regarded as a best available technique for the treatment of complex industrial wastewaters containing high-strength ammonium concentrations and phenolic compounds. Aerobic granules are proven to be resistant and resilient to the shock loads, to the alternating presence of recalcitrant compounds and to starvation periods; conditions frequently found in industrial wastewater treatment plants due to changes on the industrial production schedules. In the near future, we propose the simultaneous nitritation and phenolic compounds removal should be combined with either heterotrophic denitrification or Anammox for sustainable nitrogen removal.

Continuous flow reaction using micro-reactors is a valued technology due to its excellent mass and heat transfer performance, reduced reactor volume, handling capacity of hazardous reactions, and many other process intensifications. These intensifications opportunities interest the fine chemicals, pharmaceuticals producers and other multiphase reaction users who currently use batch processes or already use continuous flow. In this thesis, elements of passive and active mixing are investigated for the application of immiscible liquid-liquid systems. In the first study, the effects of geometrical arrangements of a residence time between mixing units on the interphase mass transfer rates are evaluated with four different immiscible liquid-liquid systems. A presentation of an algorithm for the optimal selection of a reactor and its operating conditions is given in order to enable easy and improved use of one’s micro-reactor. In the second study, the impact of a secondary pulse flow on interphase mass transfer is investigated. A coil without internal baffles is used as the oscillatory-flow coil reactor with a continuous active mixing source. The best application for the reactor is determined using a comparison to other complementary continuous flow platforms in the toolbox approach. The novel advancements presented here will help lead new molecular discoveries and connect the laboratory science scale to the process engineering production scale.

O processo de transesterificação de óleos vegetais para a síntese de biodiesel por catálise básica tem sido utilizado largamente em escala industrial e altas conversões são obtidas. Entretanto, uma grande quantidade de água é necessária para a purificação dos ésteres, gerando altos volumes de rejeitos aquosos inadequados para descarte, e dessa forma, a utilização de síntese enzimática catalisada por lipases imobilizadas destaca-se como uma alternativa ao método alcalino. Este trabalho teve como objetivo aperfeiçoar a produção de biodiesel a partir de diferentes fontes de óleos vegetais por diferentes lipases imobilizadas comercialmente. Na primeira fase do trabalho foi realizada uma análise dos principais fatores envolvidos na síntese enzimática de biodiesel, com foco nos parâmetros envolvidos na escolha e na configuração dos reatores. Uma extensa discussão foi apresentada sobre as vantagens e desvantagens de cada tipo de reator e seu modo de funcionamento. O cenário atual do mercado de síntese enzimática de biodiesel e algumas perspectivas futuras também foram apresentadas. Na segunda etapa desta pesquisa foi testado o conceito “combi-lipase”, que se baseia no uso de misturas de lipases com diferentes especificidades para a cadeia molecular de um óleo em particular (o substrato). Neste caso, foram utilizadas as lipases comerciais imobilizadas Novozym 435 (CALB), Lipozyme TL-IM (TLL), e Lipozyme RM-IM (RML) como biocatalisadoras na síntese de biodiesel via transesterificação enzimática dos óleos de oliva e palma, com etanol como aceptor acila. Repetidas reações em batelada foram realizadas para testar a estabilidade operacional do sistema combi-lipase, em que elas puderam ser usadas em pelo menos sete ciclos, mantendo em torno de 80 % da sua atividade inicial. Dando sequencia ao conceito de combi-lipase, na terceira etapa dessa pesquisa, foi avaliada a utilização de substratos alternativos, como os provenientes de fritura doméstica e comercial, comparada ao óleo de soja. As reações foram conduzidas em banho de ultrassom, com a otimização dos parâmetros razão molar etanol:óleo, quantidade de água adicionada na reação e quantidade de biocatalisador (previamente à definição da composição do combi-lipase). O uso de tecnologia de ultrassom, concomitante com a aplicação de misturas de enzimas com diferentes preços de aquisição e uso de óleos residuais apresentou excelentes rendimentos, com 90 % (com óleo de soja) e 70 % (com óleo residual) de conversão de biodiesel. Na última etapa deste trabalho, foi conduzida a síntese contínua de biodiesel em um reator de leito empacotado (PBR) com o uso de etanol e dos substratos óleos de soja e óleo residual, utilizando combi-lipase com biocatalisador. Após a otimização de alguns parâmetros de reação, foram definidas as seguintes condições: utilização de pérolas de vidro misturada ao combi-lipase para compor o leito enzimático; uso de terc-butanol como solvente de reação e velocidade de fluxo de 0,08 mL min-1. O combi-lipase apresentou excelente estabilidade operacional, e o reator manteve-se operando continuamente por 30 dias em estado estacionário. Independente do tipo de substrato empregado, o rendimento de conversão manteve-se em torno de 50 %, com produtividade de 1,94 gbiodiesel gsubstrato-1 h-1.<br>The process of transesterification of vegetable oils for biodiesel synthesis catalyzed by alkalis has been widely used on an industrial scale and high conversions are obtained. However, a large amount of water is required for the purification of esters, generating large amounts of aqueous wastes, unsuitable for disposal. Therefore, the enzymatic synthesis of biodiesel using immobilized lipases as biocatalysts stands as an alternative to the alkaline method. This work aimed at enhancing the production of biodiesel from different sources of vegetable oils using different immobilized commercially available lipases. In the first step of the work, an analysis of the main factors involved in enzymatic synthesis of biodiesel was carried out, focusing on choices of immobilization protocol and parameters involved in the selection and configuration of the reactors. An extensive discussion is presented on the advantages and disadvantages of each type of reactor and its operation. The current scenario of the enzymatic synthesis of biodiesel market and some future prospects are also presented. In the second stage of this study it was tested the concept "combi-lipase", which is based on the use of lipase mixtures with different specificities for a particular oil, the substrate. The immobilized commercial lipases Novozym 435 (CALB), Lipozyme TL-IM (TLL), and Lipozyme RM-IM (RML) were used as biocatalysts in enzymatic transesterification of biodiesel from olive and palm oils, with ethanol as acyl acceptor. Repeated batches of reaction were carried out in order to test the operational stability of the combi-lipase systems, with results showing that they could be used for at least seven cycles keeping higher than 80 % of their initial activities. Following the concept of combi-lipase, in the third stage of this research, it was evaluated the use of alternative substrates, such as waste frying oils, compared to soybean oil. The reactions were conducted in an ultrasonic bath, with the optimization of the molar ratio of ethanol: oil, amount of water added in the reaction and amount of biocatalyst (prior to the definition of the combi-lipase composition). The use of ultrasonic technology, concomitant with the application of mixtures of enzymes with different acquisition and use prices of residual oils presented excellent yields, with 90 % (with soybean oil) and 70 % (with residual oil) of biodiesel conversion. Finally, in the last stage of this work, the combi-lipase concept was applied in the continuous ethanolysis of biodiesel in a packed bed reactor (PBR) with the use of soybean and waste oils as substrates. After optimization of some reaction parameters, the following conditions were defined: use of glass beads mixed with lipases to compose the enzymatic bed; Use of tert-butanol as reaction solvents and flow rate of 0.08 mL min-1. The combi-lipase presented excellent operational stability, and the reactor was continuously operated for 30 days at steady state. Regardless of the type of substrate used, the conversion yield remained around 50 %, with productivity of 1.94 gbiodiesel gsubstrate-1 h-1.

Le furfural (FF) et le 5-hydroxyméthylfurfural (HMF) ont été identifiés comme d'importants produits chimiques polyvalents d'origine biologique. Leurs produits d'oxydation, de réduction, d'hydrolyse et de polymérisation ont suscité un grand intérêt pour leur haute valeur ajoutée et leurs vastes applications. L'objectif de ce travail de doctorat est de réaliser la conversion du FF et du HMF en produits de haute valeur en aval dans des procédés conventionnels et d'intensification. La comparaison entre le chauffage conventionnel et la méthode de chauffage par micro-ondes, par lots avec un régime d'écoulement continu a été explorée en ce qui concerne les dérivés des FF et la réaction de valorisation du HMF. Le développement de catalyseurs plus écologiques, durables et efficaces pour réaliser la conversion des composés d'origine biologique a été étudié. Des composés cibles tels que le lévulinate de méthyle (ML), la gamma-valérolactone (GVL), l'acide 5-hydroxyméthyl-2-furancarboxylique (HMFCA), l'acide 2,5-furandicarboxylique (FDCA) ont été étudiés. En même temps, l'application du FDCA a également été effectuée, la production de trois différents types de polyesters à base de furanne : le polyéthylène-2,5-furandicarboxylate (PEF), le polyhydropropyl-2,5-furandicarboxylate (PHPF) et le polydiglycérol-2,5-furandicarboxylate (PDGF) ont été réalisés par polytransestérification entre le diéthyl furane-2,5-dicarboxylate (DEFDC) et un prépolymère défini à base de diol-furanne ou de diglycérol pur. Plusieurs questions importantes ont été soulevées afin de concevoir des processus plus écologiques que les processus actuels. Par exemple, les expériences pour l'oxydation du HMF ont été réalisées dans l'eau. L'irradiation par micro-ondes a été choisie comme méthode de chauffage pour accélérer la réaction. Les réacteurs à flux continu, tels que Pheonix, H-cube Pro ainsi que les micro-ondes à flux continu ont été identifiés comme des alternatives intéressantes pour améliorer la productivité des composés cibles. En conséquence, des résultats prometteurs ont été obtenus du point de vue de l'industrie<br>Furfural (FF) and 5-hydroxymethylfurfural (HMF) have been identified as important bio-based versatile chemicals, their oxidation, reduction, hydrolysis and polymerization products attracted more interests for the high value and Wide applications. The aim of this PhD work is to realize the conversion of FF and HMF into high value downstream products in both conventional and intensification processes. Therefore, the comparation between conventional heating and microwave heating method, batch With continuous flow regime was explored regarding FF derivatives and HMF valorization reaction in my work. The development of greener, durable and efficient catalysts to realize the conversion of bio-based compounds has been employed. Target compounds such as methyl levulinate (ML), gamma-valerolactone (GVL), 5-hydroxymethyl-2-furancarboxylic acid (HMFCA), 2,5-furandicarboxylic acid (FDCA) were investigated. At the same time, the application of FDCA was also performed, the production of three differen kinds of furan-based polyesters: polyethylene-2,5-furandicarboxylate (PEF), polyhydropropyl-2,5furandicarboxylate (PHPF) and polydiglycerol-2,5-furandicarboxylate (PDGF) were realized through polytransesterification between diethyl furan-2,5-dicarboxylate (DEFDC) and a defined diol furan-based prepolyme or pure diglycerol. Several important issues were identified in order to design processes greener than the current ones. For instance, the experiments for HMF oxidation were performed in water. Microwave irradiation has been chosen as the heating method to accelerate the reaction. Continuous flow reactors, such as Pheonix, H-cube Pro as well as microwave continuous flow were identified as interesting alternatives to improve the productivities of target compounds. As a result, some promising results were obtained in the viewpoint of industry

Orientador: Silvio Roberto Andrietta<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica<br>Made available in DSpace on 2018-08-10T10:19:18Z (GMT). No. of bitstreams: 1 Galassi_GabrielRamos_M.pdf: 1009774 bytes, checksum: 86a841b010532edff0ac4939c19472f4 (MD5) Previous issue date: 2007<br>Resumo: Este trabalho tem por objetivo a realização de um estudo aprofundado do processo de fermentação alcoólica contínua em que são utilizados reatores tubulares tipo torre e células auto-imobilizadas. Buscou-se nesse projeto a seleção entre quatro cepas com características floculantes e perfis metabólicos adequados ao trabalho em tais reatores. O anseio por melhorias no sistema de fermentação contínua com células auto-imobilizadas se dá em função da busca por métodos com reduzido custo de produção do etanol, o que ocorre nesse sistema, onde inexiste a necessidade da utilização de unidades de separação de células (centrifugas), reduzindo assim em torno de 15% o custo final do preço do produto acabado. As linhagens utilizadas foram quatro cepas do gênero Saccharomyces cerevisiae com características floculantes e formadoras de partículas esféricas (pellets) quando cultivadas em mesa agitadora circulatória. Duas dessas cepas selecionadas foram obtidas da unidade de fermentação industrial da Usina Junqueira (Igarapava/SP), isoladas durante a safra de janeiro de 2000, são elas as cepas JU C2 e JU C4, outras duas cepas foram obtidas através de recentes isolamentos no Departamento de Biotecnologia e Processos do CPQBA/Unicamp, cepas G1 e G2. No processo de otimização foram utilizados dois reatores tubulares em série, um primeiro reator (R1) recebia um substrato concentrado de sacarose, diluído em linha visando atingir concentrações pré-determinadas para o uso nos experimentos e um segundo reator (R2) que recebia o efluente (vinho fermentado) proveniente de R1. Foram realizados quatro experimentos, cada qual com uma linhagem diferente. Os experimentos tiveram entre 20 a 25 dias de duração cada, porém, para fins de padronização foram selecionados 12 dias de ensaios. Durante os experimentos, diferentes vazões de alimentação aos reatores foram testadas, estas alternaram de forma crescente entre 1,2; 1,5; 1,8 e 2,1 L/h de substrato. Amostras foram retiradas do sistema e analisadas quanto à quantidade de sólidos solúveis, quantidade de ART, etanol produzido e vazão real do sistema. Ao término de cada experimento foram realizadas análises de cariotipagem, potencial de floculação por absorbância e determinação da floculação pela expressão dos genes FLO5 e FLO10. De forma geral, todas as linhagens estudadas mostraram-se hábeis ao trabalho em biorreatores fluidizados, desde que sejam respeitados seus limites metabólicos atuando nesse tipo de reatores. As linhagens JU C4 e G1 sobressaíram-se entre as demais pelo comportamento flexível e adaptável diante das situações impostas ao longo do projeto. Foram capazes de formar leitos celulares estáveis e com bom desempenho na conversão de açúcares á etanol. As linhagens JU C2 e G2 apresentaram também bons resultados na produção de etanol, no entanto, seus perfis como linhagens floculantes exigem uma maior cautela na utilização das mesmas em processos fermentativos. JU C2 com baixo poder floculante, formando por vezes leitos pouco estáveis e G2 com grande poder floculante, formando por vezes leitos compactos com canais preferenciais de passagem de substrato<br>Abstract: using flocculation yeasts of Saccharomyces cerevisiae in fixed bed tower reactors for ethanol production. We sought, through this job, the selection between four flocculent yeasts strains with appropriate metabolic profile to work in this kind of reactor. The selected yeasts strains present strong flocculent characteristics and there is no need to use cell separation unity (centrifuge) after the fermentation process reducing around 15% the costs of ethanol production. Two of these strains, JU C2 and JU C4, were collected from an industrial fermentation unity at Usina Junqueira (Igarapava/SP) during the crop of 2000. The other two strains, G1 and G2, were collected from CPQBA/Unicamp. In the operational optimization were used two fixed bed type tower reactors connected in series, a first one (R1) receive a concentrated sucrose medium diluted in line for reach predetermined concentrations and a second one (R2), that receive fermented wine from the first (R1). The fermentations experiments had between 20 or 25 days, but for standardization of the work 12 days of assays were selected. During the experiments, different feed outflow were tested in the reactors, these had been alternated in a increasing way between 1,2; 1,5; 1,8 and 2,1 L/h of medium. Samples were collected from the system and analyzed the amount of soluble solids, amount of reducing sugars, ethanol and real outflow of the system. In the ending of each experiment were analyzed the karyotyping profile and flocculating potential by absorbance method and expression of the FLO1 and FLO10 genes. The results confirm that all the studied strains are able to work in fluidized bioreactors since their metabolic limits where respected. The best results were obtained with JU C4 and G1 strains. They show a flexible and adaptable behavior ahead the tested situations in this job. They were capable to form steady beds and demonstrate good performance in sugar conversion to ethanol. The other strains, JU C2 and G2, showed nice results in the production of ethanol, however their flocculent profiles demand caution when used in fermentation processes. JU C2 has a low flocculent power forming sometimes unstable cell beds and G2 has a high flocculent power forming sometimes compact cell beds with preferential channels of medium passage<br>Mestrado<br>Desenvolvimento de Processos Biotecnologicos<br>Mestre em Engenharia Química

A sacarose é uma matéria-prima, cuja produção é considerada ecologicamente correta, sendo o Brasil seu maior produtor e exportador. O dissacarídeo pode ser convertido, através de um processo multienzimático, em substâncias de maior valor agregado: frutose e ácido glicônico, as quais são importadas pelo Brasil, tendo amplo uso nos setores químico, farmacêutico e alimentício. A conversão foi feita através da ação da invertase, glicose oxidase e catalase, utilizando os reatores descontínuo e contínuo. No procedimento utilizando reator descontínuo, o tempo de residência é igual para reagentes, produtos e catalisador. Neste caso as enzimas foram adicionadas seqüencialmente, em um primeiro momento, e na segunda etapa foram adicionadas simultaneamente. Os parâmetros de partida, a saber, concentração inicial de sacarose, pH, temperatura e atividades enzimáticas, foram testados em diferentes quantidades no intuito de encontrar a mistura inicial mais eficiente na conversão do substrato. No procedimento contínuo, utilizou-se reator com membrana, da marca MILLIPORE®, que permite integrar em uma única etapa a conversão catalítica, a separação/concentração do produto e a recuperação do biocatalisador. A temperatura foi controlada por circulação de água, tendo acoplado uma bomba peristáltica (para controlar a vazão de alimentação do substrato) e um sistema de pressurização. O reator operou com membrana de ultrafiltração (corte molecular = 100 kDa) e foi mantido sob agitação constante. Os parâmetros de partida, neste reator, foram fixados de acordo com os valores otimizados no reator descontínuo com o emprego simultâneo das enzimas.<br>Sucrose is produced in large amount in Brazil, being a worldwide commercialized commodity. However, it can be converted into more valuable products such as fructose and gluconic acid, both used largely in the chemical, pharmaceutical and food industry. Conversion occurred through the action of invertase, glucose oxidase and catalase, using the discontinuous and continuous reactors. In the batch reactor, the residence time is equal to reactants, products and catalyst. In this case, enzymes were added sequentially, at first, and in the second step were added simultaneously. Boot parameters, initial sucrose concentration, pH, temperature and enzyme activities were tested in different amounts in order to find the most efficient initial mixture to the conversion of the substrate. In continuous process, we used the membrane reactor, MILLIPORE®, which allows for one-step catalytic conversion, the separation / concentration of the product and recovery of the biocatalyst. The temperature was controlled by circulation of water, coupled with a peristaltic pump (to control the feed flow of the substrate) and a pressurization system. The reactor was operated with ultrafiltration membrane (molecular cutoff = 100 kDa) and was kept under constant agitation. The initial parameters in this reactor were set according to the values optimized in the batch reactor with the simultaneous use of enzymes.

<p>Käppala wastewater treatment plant situated on the island of Lidingö northeast of Stockholm is running a project during 2004 and 2005 with the purpose to map out the capacity of anaerobic digestion in the digesters that treat primary and excess sludge. The purpose of this thesis work, which is part of that project, was to characterize the present anaerobic digestion process and to investigate its capacity to treat other organic wastes such as restaurant waste and waste from water works. To decide the potential of both methane and biogas production from different substrates batch laboratory tests were carried out. To imitate the anaerobic digestion process at Käppala continuous tests with small scale reactors were carried out. These reactors were later fed with restaurant waste.</p><p>The batch laboratory tests showed that primary sludge had a potential biogas and methane production of 0,62 and 0,35 Ndm3/g VS respectively after 40 days of digestion. After 15 to 20 days of digestion (average retention time in the digester at Käppala wastewater treayment plant that treats primary sludge) the biogas production was between 0,55 and 0,60 Ndm3/g VS, which is within the range of the production at the digester that treats the primary sludge. This leads to the conclusion that the digestion of primary sludge is well functioning at the plant.</p><p>Batch laboratory tests showed that excess sludge had a potential biogas and methane production of 0,31 and 0,16 Ndm3/g VS respectively after 40 days of digestion.</p><p>Batch laboratory tests with restaurant waste showed a potential biogas and methane production of 0,81 and 0,38 Ndm3/g VS respectively after 47 days of digestion. This means that the total production of methane gas can increase with 7-8 per cent with an annual load of 3500 tonnes of restaurant waste (estimated amount of available restaurant waste). Tests to imitate transport of restaurant waste with influent wastewater showed that 35-60 per cent of the increase of gas production would be “washed out” if the waste was tranported this way to the plant.</p><p>Batch laboratory tests with waste from water works showed that no gas was produced from this substrate.</p><p>The continuous tests with small scale reactors which were fed with restaurant waste resulted in an increase of biogas production with 12 per cent (corresponding to an annual load of 3500 tonnes of restaurant waste) compared to the present process.</p><br><p>Avloppsreningsverket Käppalaverket på Lidingö driver under år 2004-2005 ett projekt med syftet att kartlägga rötningskapaciteten i den befintliga anläggningen där primär- och överskottsslam behandlas i två rötkammare. Syftet med examensarbetet, som är en del av kartläggningsprojektet, var att karakterisera Käppalaverkets nuvarande rötningsprocess och undersöka processens kapacitet att behandla organiskt avfall i form av restaurangavfall och vatttenverksslam. För att bestämma potentialen hos olika substrat har satsvisa utrötningar genomförts. För att efterlikna processen på Käppalaverket har kontinuerliga försök med små reaktorer bedrivits. Till dessa reaktorer har sedan restaurangavfall tillsats.</p><p>De satsvisa utrötningarna av primärslam visade en potentiell bio- respektive metangasproduktion om 0,62 respektive 0,35 Ndm3/g VS efter 40 dagars utrötning. Efter 15-20 dagars utrötning (som är den genomsnittliga uppehållstiden i Käppalaverkets rötkammare där primärslammet behandlas) var biogasproduktionen mellan 0,55 och 0,60 Ndm3/g VS, vilket är inom samma intervall som vid den verkliga driften av rötkamrarna vid Käppalaverket. Detta betyder att utrötningen av primärslammet fungerar bra vid Käppalaverket.</p><p>De satsvisa utrötningarna av överskottsslammet visade en potentiell bio- respektive metangasproduktion om 0,31 respektive 0,16 Ndm3/g VS efter 40 dagars utrötning.</p><p>För restaurangavfallet visade de satsvisa utrötningarna på en potentiell bio- respektive metangasproduktion om 0,81 respektive 0,38 Ndm3/g VS efter 47 dagars utrötning.</p><p>Detta innebär att den totala metangasproduktionen vid Käppalaverket skulle kunna ökas med 7-8 procent om 3500 ton restaurangavfall skulle tas emot årligen (uppskattad mängd restaurangavfall som finns att tillgå). Försök att efterlikna transport av restaurangavfallet via avloppsledningsnätet visade dock att 35-60 procent av den ökade metangasproduktionen skulle ”tvättas ur” om avfallet fördes till verket via avloppsledningsnätet.</p><p>Försöken med satsvis utrötning av vattenverksslam visade att detta substrat inte bidrar med någon produktion av biogas eller metangas.</p><p>De kontinuerliga försöken med tillsats av restaurangavfall (motsvarande en årlig belastning med 3500 ton) resulterade i en ökning av biogasproduktionen med 12 procent.</p>

This Thesis describes how continuous flow reactors and heterogeneous catalysts have been used in conjunction with supercritical fluid solvents to develop a new process for carrying out catalytic organic reactions. The process exploits both the advantages of supercritical fluids (e.g. solvent tunability allowing facile product separation from the solvent) and heterogeneous catalysts and can be considered a 'Green' method of chemistry. Various reaction types have been explored, namely noble-metal catalysed hydrogenation reactions, supported-acid catalysed Friedel-Crafts alkylation reactions and supported-acid catalysed Friedel-Crafts acylation reactions. Chapter 1: Introduction This Chapter begins with an introduction to the concept of 'Green Chemistry' and its significance at the present time. The problems with the use of conventional solvents are highlighted, and examples of two 'greener' solvent systems - ionic liquids and supercritical fluids - are described. For each of these solvent systems, a brief review .of their use in more recent reaction chemistry is included. Chapter 2: Experimental This Chapter begins by describing the supercritical flow equipment developed at Nottingham in some detail, and includes equipment modifications which were made both to improve the effectiveness and safe operation of the equipment. The final sections of the Chapter describe the catalysts and analytical techniques used during the course of the research. Chapter 3: Continuous Hydrogenation in Supereritical Fluids This Chapter opens with a summary of some initial hydrogenation work carried out at Nottingham prior to this research. The results section reports a range of non-selective hydrogenation reactions, commencing with a detailed study of the hydrogenation of cyclohexene which was used to explore the capabilities of the equipment. Chapter 4: Continuous Selective Hydrogenation in Supercritical Fluids This Chapter is a continuation of Chapter 3 and begins with an introduction to different types of selective hydrogenation, then highlights some literature examples of selective hydrogenations conducted in supercritical fluids. The results section reports several selective hydrogenation reactions conducted at Nottingham. Chapter 5: Continuous Friedel-Crafts Alkylation and Acylation Reactions This Chapter begins with a discussion of the problems associated with conventional Friedel-Crafts chemistry, most of which are associated with the homogeneous catalysts normally used. A review of the use of various solid acid materials investigated for Friedel-Crafts type activity follows and this section concludes with literature examples of some supercritical Friedel-Crafts processes. The results section begins by reporting Friedel-Crafts alkylation reactions and closes with a brief amount ofFriedel-Crafts acylation.

In the last few decades, numerous studies have been conducted on xenobiotic compounds due to their vast use in industries, households, etc. and consequently high exposure of these compounds. The main focus of this study is nonylphenol compounds such as nonylphenol monoethoxylate (NP1EO), nonylphenol diethoxylate (NP2EO), nonylphenoxy acetic acid (NP1EC) and nonylphenol (NP), which are among the harmful xenobiotic compounds that can cause endocrine disruption, cancer and other health problems and which are used widely in the production of surfactants and personal care products. In this study, laboratory scale aerobic semi continuous reactors containing Waste Activated Sludge (WAS) spiked with NP2EO were operated for a period of 91 days, to inspect the decomposition of NP2EO in solid and liquid phases. The results obtained on the final day of operation (91st day) showed that NP2EO degraded into product compounds among which NP1EC contributed to 90% of molar mass. In general, NP2EO showed a sharp degradation while NP1EC was produced rapidly. NP1EO also showed a steady degradation. However, NP was accumulated in the reactor. During the study, TS, VS, TSS and VSS degradation was also monitored and the percentage removals were found to be between 40-60%. COD removal on the other hand was between 64-66%.