Development and scale-up studies of bio-based poly(ester-amide)s

Plastics are polymers of conventional and extensive use in our day-to-day life. This is due to their light weight, adaptability to different uses and low prices. A downside of such extensive use is the environmental pollution arising from plastic production and disposal. Indeed, many commodity polymers are produced from non-renewable resources while other do not bio-degrade after their end-of-life disposal. Consequently, the ideal polymer comes from renewable raw materials and bio-degrades after its disposal, meaning that it would do little or no harm to the environment from the beginning to the end of its life cycle. In this thesis project a class of bio-based and bio-degradable co-polymers, namely poly(ester-amide)s, was investigated because of their tunable mechanical and bio-degradation properties as well as their renewable origin. Such polymers were synthetized and characterized thermically and mechanically. Furthermore, a scale-up procedure was developed and applied to one polymer and processing trials were made with the material obtained after scale-up.

Life cycle assessment (LCA) of a bio-fuel cell fed with waste biomass: potential for scale-up and process optimization

In this Thesis, a life cycle analysis (LCA) of a biofuel cell designed by a team from the University of Bologna was done. The purpose of this study is to investigate the possible environmental impacts of the production and use of the cell and a possible optimization for an industrial scale-up. To do so, a first part of the paper was devoted to studying the present literature on biomass, and fuel cell treatments and then LCA studies on them. The experimental part presents the work done to create the Life Cycle Inventory and Life Cycle Impact Assessment. Several alternative scenarios were created to study process optimization. Reagents and energy supply were changed. To examine whether this technology can be competitive, a comparison was made with some biofuel cell use scenarios with traditional biomass treatment technologies. The result of this study is that this technology is promising from an environmental point of view in case it is possible to recover nutrients in output, without excessive energy consumption, and to minimize the use of energy used to prepare the solution.

Modeling, characterization and microalgal cultivation in an airlift panel photobioreactors.

Microalgae cultures are attracting great attentions in many industrial applications. However, one of the technical challenges is to cut down the capital and operational costs of microalgae production systems, with special difficulty in reactor design and scale-up. The thesis work open with an overview on the microalgae cultures as a possible answer to solve some of the upcoming planet issues and their applications in several fields. After the work offers a general outline on the state of the art of microalgae culture systems, taking a special look to the enclosed photobioreactors (PBRs). The overall objective of this study is to advance the knowledge of PBRs design and lead to innovative large scale processes of microalgae cultivation. An airlift flat panel photobioreactor was designed, modeled and experimentally characterized. The gas holdup, liquid flow velocity and oxygen mass transfer of the reactor were experimentally determined and mathematically modeled, and the performance of the reactor was tested by cultivation of microalgae. The model predicted data correlated well with experimental data, and the high concentration of suspension cell culture could be achieved with controlled conditions. The reactor was inoculated with the algal strain Scenedesmus obliquus sp. first and with Chlorella sp. later and sparged with air. The reactor was operated in batch mode and daily monitored for pH, temperature, and biomass concentration and activity. The productivity of the novel device was determined, suggesting the proposed design can be effectively and economically used in carbon dioxide mitigation technologies and in the production of algal biomass for biofuel and other bioproducts. Those research results favored the possibility of scaling the reactor up into industrial scales based on the models employed, and the potential advantages and disadvantages were discussed for this novel industrial design.

Espressione della proteina CRM197 in escherichia coli e purificazione mediante cromatografia di affinità

In questo lavoro di tesi sono stati confrontati diversi protocolli per la purificazione della proteina CRM197 mediante cromatografia di affinità a cationi divalenti. Il CRM197 è una variante della tossina difterica caratterizzata da stessa massa molecolare e struttura. A causa di un’unica mutazione (G52E), tale variante è atossica e presenta numerose applicazioni in campo farmaceutico (in particolare nella preparazione di vaccini coniugati). Fino ad ora, per la produzione del CRM197 è stato utilizzato il ceppo originale di derivazione, cioè Corynebacterium diphteriae, e la produzione eterologa nel batterio Escherichia coli ha mostrato notevoli difficoltà. In particolare, mentre è stato possibile definire un valido protocollo di sovraespressione e di estrazione proteica, le fasi successive di purificazione e di refolding (rinaturazione) sono ancora problematiche e causano basse rese finali, ostacolando le prospettive di scale-up su scala industriale. Il CRM197, infatti, per le sue caratteristiche strutturali, come l’elevata percentuale di amminoacidi idrofobici e la presenza di foglietti β esposti al solvente, è suscettibile alla formazione di aggregati insolubili che impone, lungo tutto il processo, il controllo delle interazioni idrofobiche (con agenti denaturanti e/o detergenti). In un precedente lavoro di tesi, è stato sviluppato un protocollo valido per ottenere un’elevata espressione proteica intracellulare. Il primo passaggio di purificazione prevede una cromatografia di affinità su colonna che viene sfruttata anche per eseguire il refolding proteico. Tuttavia, durante la messa a punto di tale processo, sono stati osservati evidenti fenomeni di aggregazione della proteina, oltre all’instaurarsi di legami aspecifici proteina-proteina o proteina-resina cromatografica. In questo lavoro di tesi sono state affrontate alcune problematiche legate a tale passaggio di purificazione per cercare di individuare le condizioni ottimali per ottenere il CRM197 in forma nativa e biologicamente attiva.

Microfluidic microbial fuel cell fabrication and rapid screening of electrochemically microbes

The demand for novel renewable energy sources, together with the new findings on bacterial electron transport mechanisms and the progress in microbial fuel cell design, have raised a noticeable interest in microbial power generation. Microbial fuel cell (MFC) is an electrochemical device that converts organic substrates into electricity via catalytic conversion by microorganism. It has represented a continuously growing research field during the past few years. The great advantage of this device is the direct conversion of the substrate into electricity and in the future, MFC may be linked to municipal waste streams or sources of agricultural and animal waste, providing a sustainable system for waste treatment and energy production. However, these novel green technologies have not yet been used for practical applications due to their low power outputs and challenges associated with scale-up, so in-depth studies are highly necessary to significantly improve and optimize the device working conditions. For the time being, the micro-scale MFCs show great potential in the rapid screening of electrochemically active microbes. This thesis presents how it will be possible to optimize the properties and design of the micro-size microbial fuel cell for maximum efficiency by understanding the MFC system. So it will involve designing, building and testing a miniature microbial fuel cell using a new species of microorganisms that promises high efficiency and long lifetime. The new device offer unique advantages of fast start-up, high sensitivity and superior microfluidic control over the measured microenvironment, which makes them good candidates for rapid screening of electrode materials, bacterial strains and growth media. It will be made in the Centre of Hybrid Biodevices (Faculty of Physical Sciences and Engineering, University of Southampton) from polymer materials like PDMS. The eventual aim is to develop a system with the optimum combination of microorganism, ion exchange membrane and growth medium. After fabricating the cell, different bacteria and plankton species will be grown in the device and the microbial fuel cell characterized for open circuit voltage and power. It will also use photo-sensitive organisms and characterize the power produced by the device in response to optical illumination.

Hydraulic evaluation of the gyro electric wave energy converter

Motivation Thanks for a scholarship offered by ALma Mater Studiorum I could stay in Denmark for six months during which I could do physical tests on the device Gyro PTO at the Departmet of Civil Engineering of Aalborg University. Aim The goal of my thesis is an hydraulic evaluation of the device: Gyro PTO, a gyroscopic device for conversion of mechanical energy in ocean surface waves to electrical energy. The principle of the system is the application of the gyroscopic moment of flywheels equipped on a swing float excited by waves. The laboratory activities were carried out by: Morten Kramer, Jan Olsen, Irene Guaraldi, Morten Thøtt, Nikolaj Holk. The main purpose of the tests was to investigate the power absorption performance in irregular waves, but testing also included performance measures in regular waves and simple tests to get knowledge about characteristics of the device, which could facilitate the possibility of performing numerical simulations and optimizations. Methodology To generate the waves and measure the performance of the device a workstation was created in the laboratory. The workstation consist of four computers in each of wich there was a different program. Programs have been used : Awasys6, LabView, Wave lab, Motive optitrack, Matlab, Autocad Main Results Thanks to the obtained data with the tank testing was possible to make the process of wave analisys. We obtained significant wave height and period through a script Matlab and then the values of power produced, and energy efficiency of the device for two types of waves: regular and irregular. We also got results as: physical size, weight, inertia moments, hydrostatics, eigen periods, mooring stiffness, friction, hydrodynamic coefficients etc. We obtained significant parameters related to the prototype in the laboratory after which we scale up the results obtained for two future applications: one in Nissun Brending and in the North Sea. Conclusions The main conclusion on the testing is that more focus should be put into ensuring a stable and positive power output in a variety of wave conditions. In the irregular waves the power production was negative and therefore it does not make sense to scale up the results directly. The average measured capture width in the regular waves was 0.21 m. As the device width is 0.63 m this corresponds to a capture width ratio of: 0.21/0.63 * 100 = 33 %. Let’s assume that it is possible to get the device to produce as well in irregular waves under any wave conditions, and lets further assume that the yearly absorbed energy can be converted into electricity at a PTO-efficiency of 90 %. Under all those assumptions the results in table are found, i.e. a Nissum Bredning would produce 0.87 MWh/year and a North Sea device 85 MWh/year.

Synthesis and organocatalyzed enantioselective transfer-hydrogenation of beta-amino nitroolefins

The importance of the β-amino nitroalkanes is due to their high versatility allowing a straightforward entry to a variety of nitrogen-containing chiral building blocks; furthermore obtaining them in enantiopure form allows their use in the synthesis of biologically active compounds or their utilization as chiral ligands for different uses. In this work, a reaction for obtaining enantiopure β-amino nitroalkanes through asymmetric organocatalysis has been developed. The synthetic strategy adopted for the obtainment of these compounds was based on an asymmetric reduction of β-amino nitroolefins in a transfer hydrogenation reaction, involving an Hantzsch ester as hydrogen source and a chiral thiourea as organic catalyst. After the optimization of the reaction conditions over the β-acyl-amino nitrostyrene, we tested the reaction generality over other aromatic compound and for Boc protected substrate both aromatic and aliphatic. A scale-up of the reaction was also performed.

Crescita della Chlorophyta Haematococcus pluvialis in risposta alla variazione di componenti chimici del terreno di coltura

Haematococcus pluvialis è una delle specie microalgali di maggior interesse biotecnologico, poiché rappresenta la maggior fonte naturale del pigmento astaxantina, carotenoide molto ricercato nell’ industria mangimistica, nutraceutica, cosmetica e farmacologica. La produzione massiva di questa specie è ancora caratterizzata da numerose limitazioni allo scale-up; il principale collo di bottiglia della coltivazione è rappresentato dalla crescita lenta e dal relativamente basso numero di cellule finali che vengono raggiunte, traducendosi in una minore quantità di astaxantina prodotta. Lo scopo di questo lavoro è stato quello di provare ad incrementare le velocità di crescita della fase iniziale dello stadio vegetativo dell’alga, utilizzando sostanze di crescita quali fitoormoni, sostanza organica, vitamine e medium formulati con diversi rapporti N/P, in modo tale da ottenere un maggiore numero di cellule che possono essere indotte a produrre astaxantina. Alcune condizioni hanno mostrato effetti sulla crescita, tuttavia la condizione che ha fornito un maggior incremento come numero di cellule è stata quella caratterizzata dall’utilizzo di un basso valore del rapporto N/P, rispetto al valore solitamente utilizzato per questa specie. Nonostante siano necessari ancora diversi sforzi per individuare i fattori biotici e abiotici che regolano la crescita di H. pluvialis nell’ottica di una produzione massiva, il principale collo di bottiglia di questo processo può essere quindi ridotto con l’utilizzo delle sostanze stimolanti la crescita sperimentate in questo lavoro e dalla formulazione di medium di crescita che forniscano un compromesso tra un alto numero di cellule finali e costi di produzione relativamente contenuti.

Sviluppo e applicazione di un reattore di prepolimerizzazione in continuo

Presso lo stabilimento DOW di Correggio (che è una system house per la produzione di prepolimeri poliuretanici) la ricerca è attualmente incentrata sullo sviluppo su scala industriale di un reattore pilota continuo di tipo plug flow che andrà a sostituire i tradizionali processi BATCH, con un guadagno in termini di sicurezza e costi di investimento. In particolare, il progetto prevedeva di sperimentare le “ricette” attuali di prepolimeri per applicazioni nel settore della calzatura per valutarne l’equivalenza con quelli fatti in BATCH, e di calibrare un modello del reattore pilota che permetta di prevedere le prestazioni del reattore e supporti lo scale-up attraverso la raccolta di dati sperimentali (profili di temperatura, tempi di residenza, titolo di NCO del prodotto, ecc...). Alla conclusione del progetto è possibile affermare che la tecnologia è robusta, scalabile e rispetto ai sistemi di produzione attuale presenta una maggiore produttività, sicurezza e minori costi di investimento. At the DOW plant in Correggio, which is a system house for the production of polyurethane prepolymers, the research is currently focused on the develompment and application of a plug flow type continuos reactor that will replace the traditional BATCH processes, with advantages in terms of process safety an investment costs. In particular, the project aims were to test in the pilot plant the prepolymer receipts for footwear application, find out if the result products were similar or better than the ones made with BATCH reactor and harvest experimental data (such as temperatures profiles, reaction time, residual NCO value, etc...) in order to calibrate a model that will support the scale-up to the industrial plant. Now that the project is ended, it is possibile to assert that this tecnology is reliable, scalable, safer and cheaper than the old processes.

Nuovi processi catalitici per la produzione di syngas

The study of the combined Steam/Dry Reforming (S/DR) process for the production of syngas (CO + H2) from clean biogas was carried out using Ni/Ir bimetallic catalysts on Mg and Al mixed-oxides, obtained by calcination of hydrotalcite-type precursors (Ht) prepared by co-precipitation. The presence of small amounts of Ir promoted the catalytic activity and limited the deactivation phenomena through the formation of a bimetallic alloy, which does the catalyst very active even at lowest temperature and in lack of steam. By integrating a High Temperature–WGS unit (HTS) after the S/DR reactor it was possible to increase the H2 yield of the process. The performance of the Zn/Al/Cu-based catalyst was improved using a templating agent during the synthesis of the catalyst, which increased the catalyst’s structural properties and activity especially at lowest temperatures and at highest contact times. Finally, starting from the laboratory data, it was possible to simulate the S/DR process on industrial scale, evaluating its scalability and environmental impact. The results showed that, using the S/DR technology instead of the current processes, it was possible to reduce the energy costs and the atmospheric emissions of the plant.

Studio del reforming combinato del biogas su nanoparticelle bimetalliche supportate

The study of the combined reforming (CR) process to produce synthesis gas (CO + H2) feeding Clean Biogas (CB, biogas in which the main pollutants have been removed) has been performed on Ni-based bimetallic catalysts promoted by small amounts of Rh or Cu, prepared by incipient wetness impregnation or coprecipitation of different precursors on mixed oxides Mg/Al/O obtained by calcination of hydrotalcite-type (Ht) coprecipitates. It has been observed as the formation of bimetallic particles promoted the catalytic activity and limited the deactivation phenomena, allowing to operate at lower temperature and feeding lower amounts of steam. By this way, it was possible to define the best promoter, to tune its amount and the formation of the bimetallic nanoparticles. Finally, it has been simulated the scale-up of the CR process to industrial level, evaluating the feasibility and economic degree by comparison with the industrially exploited Autothermal reforming (ATR) process, evidencing the possible scalability and the advantages at environmental and energetic level in comparison to the current reforming processes.

Valorizzazione della sansa d'oliva: estrazione ed analisi della frazione fenolica

Il presente elaborato di tesi espone uno studio scientifico che ha come obbiettivo quello di valutare un metodo sostenibile per il recupero della frazione fenolica presente nella sansa d’oliva vergine, il sottoprodotto solido dell’industria olearia. L’attività di ricerca ha riguardato prove sperimentali di estrazione di tali composti minori polari da sanse d’oliva vergini successivamente caratterizzate con metodi analitici (Folin-Ciocâlteu, UHPLC-DAD). Lo scopo finale di questo studio è l’ottenimento di un estratto idroalcolico caratterizzato per il contenuto in componenti polari ad attività riducente, quali le molecole fenoliche; si intende quindi ottenere un semilavorato ad alto valore aggiunto che possa essere conferito successivamente all’industria alimentare, cosmetica, farmaceutica, per la produzione di prodotti funzionali con proprietà bioattive. Questo studio è orientato verso un concetto di innovazione di metodi efficaci per la valorizzazione di questi scarti. Il lavoro compiuto ha confermato la possibilità di valorizzare la sansa d’oliva in maniera sostenibile in un’ottica di economia circolare, con ottenimento di estratti idro-alcolici interessanti in termini di contenuto in composti ad attività riducente riconducibili, con molta probabilità, soprattutto a molecole a struttura fenolica. Gli studi preliminari sulle sanse hanno permesso di individuare il campione ideale da sottoporre al processo di valorizzazione, ovvero la sansa trifasica ma, salvo un costo maggioritario in termini energetici durante la fase di evaporazione dell’estratto filtrato, grazie al metodo messo a punto, possono essere valorizzate sanse sia bifasiche che trifasiche denocciolate. Le tecnologie considerate, quali ad esempio presse, sistemi di centrifugazione ed evaporazione e solventi “green’’ quali l’etanolo, suggeriscono la possibilità di uno scale-up a livello industriale per la produzione di estratti caratterizzati per il contenuto in composti riducenti e fenolici.

Testing of subgrid scale (SGS) models for large-eddy simulation (LES) of turbulent channel flow

Sub-grid scale (SGS) models are required in order to model the influence of the unresolved small scales on the resolved scales in large-eddy simulations (LES), the flow at the smallest scales of turbulence. In the following work two SGS models are presented and deeply analyzed in terms of accuracy through several LESs with different spatial resolutions, i.e. grid spacings. The first part of this thesis focuses on the basic theory of turbulence, the governing equations of fluid dynamics and their adaptation to LES. Furthermore, two important SGS models are presented: one is the Dynamic eddy-viscosity model (DEVM), developed by \cite{germano1991dynamic}, while the other is the Explicit Algebraic SGS model (EASSM), by \cite{marstorp2009explicit}. In addition, some details about the implementation of the EASSM in a Pseudo-Spectral Navier-Stokes code \cite{chevalier2007simson} are presented. The performance of the two aforementioned models will be investigated in the following chapters, by means of LES of a channel flow, with friction Reynolds numbers $Re_\tau=590$ up to $Re_\tau=5200$, with relatively coarse resolutions. Data from each simulation will be compared to baseline DNS data. Results have shown that, in contrast to the DEVM, the EASSM has promising potentials for flow predictions at high friction Reynolds numbers: the higher the friction Reynolds number is the better the EASSM will behave and the worse the performances of the DEVM will be. The better performance of the EASSM is contributed to the ability to capture flow anisotropy at the small scales through a correct formulation for the SGS stresses. Moreover, a considerable reduction in the required computational resources can be achieved using the EASSM compared to DEVM. Therefore, the EASSM combines accuracy and computational efficiency, implying that it has a clear potential for industrial CFD usage.

Outdoor production of Isochrysis galbana (T-iso) in industrial scale photobioreactors and modelling of its photosynthesis and respiration rate

Isochrysis galbana is a widely-used strain in aquaculture in spite of its low productivity. To maximize the productivity of processes based on this microalgae strain, a model was developed considering the influence of irradiance, temperature, pH and dissolved oxygen concentration on the photosynthesis and respiration rate. Results demonstrate that this strain tolerates temperatures up to 35ºC but it is highly sensitive to irradiances higher than 500 µE·m-2·s-1 and dissolved oxygen concentrations higher than 11 mg·l-1. With the researcher group of the “Universidad de Almeria”, the developed model was validated using data from an industrial-scale outdoor tubular photobioreactor demonstrating that inadequate temperature and dissolved oxygen concentrations reduce productivity to half that which is maximal, according to light availability under real outdoor conditions. The developed model is a useful tool for managing working processes, especially in the development of new processes based on this strain and to take decisions regarding optimal control strategies. Also the outdoor production of Isochrysis galbana T-iso in industrial size tubular photobioreactors (3.0 m3) has been studied. Experiments were performed modifying the dilution rate and evaluating the biomass productivity and quality, in addition to the overall performance of the system. Results confirmed that T-iso can be produced outdoor at commercial scale in continuous mode, productivities up to 20 g·m-2·day-1 of biomass rich in proteins (45%) and lipids (25%) being obtained. The utilization of this type of photobioreactors allows controlling the contamination and pH of the cultures, but daily variation of solar radiation imposes the existence of inadequate dissolved oxygen concentration and temperature at which the cells are exposed to inside the reactor. Excessive dissolved oxygen reduced the biomass productivity to 68% of maximal, whereas inadequate temperature reduces to 63% of maximal. Thus, optimally controlling these parameters the biomass productivity can be duplicated. These results confirm the potential to produce this valuable strain at commercial scale in optimally designed/operated tubular photobioreactors as a biotechnological industry.