Enzymatic Synthesis of Ampicillin: Nonlinear Modeling, Kinetics Estimation, and Adaptive Control

Nowadays, the use of advanced control strategies in biotechnology is quite low. A main reason is the lack of quality of the data, and the fact that more sophisticated control strategies must be based on a model of the dynamics of bioprocesses. The nonlinearity of the bioprocesses and the absence of cheap and reliable instrumentation require an enhanced modeling effort and identification strategies for the kinetics. The present work approaches modeling and control strategies for the enzymatic synthesis of ampicillin that is carried out inside a fed-batch bioreactor. First, a nonlinear dynamical model of this bioprocess is obtained by using a novel modeling procedure for biotechnology: the bond graph methodology. Second, a high gain observer is designed for the estimation of the imprecisely known kinetics of the synthesis process. Third, by combining an exact linearizing control law with the on-line estimation kinetics algorithm, a nonlinear adaptive control law is designed. The case study discussed shows that a nonlinear feedback control strategy applied to the ampicillin synthesis bioprocess can cope with disturbances, noisy measurements, and parametric uncertainties. Numerical simulations performed with MATLAB environment are included in order to test the behavior and the performances of the proposed estimation and control strategies

What makes Yarrowia lipolytica well suited for industry?

Yarrowia lipolytica possesses natural and engineered traits that make it a good host for the industrial bioproduction of chemicals, fuels, foods, and pharmaceuticals. In recent years, academic and industrial researchers have assessed its potential, developed synthetic biology techniques, improved its features, scaled its processes, and identified its limitations. Both publications and patents related to Y. lipolytica have shown a drastic increase during the past decade. Here, we discuss the characteristics of this yeast that make it suitable for industry and the remaining challenges for its wider use at large scale. We present evidence herein that shows the importance and potential of Y. lipolytica in bioproduction such that it may soon be one of the preferred choices of industry

Systems and control : 21th Benelux meeting, 2002, March 19-21, Veldhoven, The Netherlands

Book of abstract

Respirometric techniques applied to aerobic microbial processes

Tese de doutoramento em Chemical and Biological Engineeringerobic microbial processes are extremely important in environmental biotechnology, namely in biological wastewater treatment where activated sludge process represents nowadays the most widespread technology for wastewater purification. The availability of reliable, cheap and versatile real-time monitoring tools providing information on the biological activity is of crucial importance for monitoring and control of bioprocesses, avoiding possible operational troubles through early detection of problems. This thesis aimed to develop and apply respirometric techniques for the estimation of kinetic and stoichiometric parameters in different systems with increasing complexity. The first process – nitrification, was chosen for its simplicity. In this process, substrate consumption is related only with growth and energy, no storage phenomena occur. The ASM1 model was used to fit the respirometric data, and an in situ pulse respirometric method was validated for the determination of kinetic and stoichiometric parameters of the system at steady state: the maximum exogenous oxygen uptake rate was determined respirometrically [61.15 (4.09) mg O2 L-1 h-1] through the injection of increasing substrate concentration pulses; the biomass growth yield was estimated from respirometric data and by the traditional COD (Chemical Oxygen Demand) mass balance method, and both methods gave similar values [0.10 (0.07) and 0.09 (0.04) g X-COD g NOD-1, respectively]; the affinity constant was indirectly estimated after fitting the ascending part of the respirogram to a theoretical model, and an average value of 0.48 (0.08) mg NH4-N L-1 was obtained. Model adjustment was successfully applied to a portion of the respirogram, but not to the complete respirogram. It was concluded that a more complex model, taking into account biological and electrode response time, should give better correlation. Additionally, two methods for the determination of the oxygen volumetric mass transfer coefficient were tested and it was concluded that the dynamic method was the most adequate. The results obtained allowed to establish the basic pulse respirometric methodology, and also the best method for estimating the oxygen mass transfer coefficient. Then a Pseudomonas putida pure culture system was chosen to test the applicability of pulse respirometry on biomass with storage ability ASM3 was used for fitting the obtained data. The model included terms which took into account the biological and electrode response time, thus the entire respirogram could be successfully used for model fitting. The pulse respirometric method was validated for estimation of kinetic and stoichiometric parameters in pure cultures by comparison with the traditional chemostat method. No significance difference was observed between parameters estimated by chemostat and respirometric methods: biomass growth yield was 0.41(0.05) and 0.51 (0.04) g COD-X g COD-S-1; affinity constant was 4.86 (0.70) and 5.13 (1.99) mg COD-S L-1; maximum specific growth rate was 0.20 (0.05) and 0.16 (0.01) h-1, with chemostat and respirometry respectively. Pulse respirometry was then applied to a continuous suspended activated sludge process, fed with a complex synthetic medium. In this stage, a multiple pulses respirometric method was tested and validated by comparison with chemostat method and with ASM1 model fitting: biomass growth yield was in the range of 0.37 – 0.76, and 0.37 – 0.65 g COD-X g COD-S-1; maintenance coefficient was 0.012 (0.012) and 0.010 (0.006) h-1, by COD mass balance and by respirometry, respectively; affinity constant and maximum specific oxygen consumption rate were estimated with the multiple concentration pulses respirometric method to be 15.5 (2.4) mg COD-S L-1 and 0.12 (0.01) h-1, respectively. Considering the assessment and comparison of the experimental and calculation methods, it was concluded that the estimation of kinetic and stoichiometric parameters in mixed aerobic cultures should preferentially be performed by using respirometric techniques, being the most adequate method the multiple concentration pulses injection method, with several advantages such as a simpler experimental data interpretation, and results with better confidence. The developed multiple pulses respirometric method was finally applied to an aerobic granular system. The method proved to be adequate for parameter estimation on this system, and allowed the successful monitoring of aerobic granulation. In a short time and using low cost equipment, the method allowed an exhaustive characterisation of the process in real-time through the determination of six central parameters: (i) biomass growth yield, (ii) specific endogenous respiration rate, (iii) substrate affinity constant, (iv) maximum specific oxygen consumption rate, (v) maximum specific substrate consumption rate, and (vi) maximum specific growth rate. The pulse respirometric method presented the advantage of the determined parameters being those actually prevailing in the system under actual operating conditions, i.e. apparent parameters, which is of major interest for control and process operation. At steady state the biomass growth yield was estimated to be 0.6 g COD-X g COD-S-1, the specific endogenous respiration rate was 0.1 g O2 g COD-X-1 d-1, the affinity constant was approximately 20 mg COD-S L-1, maximum specific oxygen consumption rate and maximum specific substrate consumption rate were 0.06 g O2 g COD-X-1 h-1 and 0.17 g COD-S g CODX- 1 h-1, respectively, and the maximum specific growth rate was roughly 2.5 d-1. The potential of the proposed multiple concentration pulses respirometric method was investigated for monitoring aerobic granular sludge systems, and controlling aeration in an efficient mode. Additionally the multiple concentration pulses respirometric method was applied in two aerobic granular sludge systems operated under different aeration rates (5.0 and 6.6 L min-1), and allowed to assess the influence of shear stress on the biomass kinetic and stoichiometric parameters: the biomass growth yield was higher for the sludge cultivated under higher shear stress [0.6 (0.02) versus 0.5 (0.02) g COD-X g COD-S-1 at lower shear stress]; biomass subjected to the higher shear stress presented a higher substrate affinity constant [16.4 (2.6) and 9.1 (0.2) mg COD-S L-1, at higher and lower shear stress, respectively]; and also a higher maximum specific substrate consumption rate [5.4 (0.9) and 2.5 (0.5) g COD-S g COD-X d-1, at higher and lower shear stress, respectively] at the end of the aerobic granulation process. The global conclusion withdrawn from this thesis is that respirometry, especially pulse respirometry, is a valid and promising technique for kinetic and stoichiometric characterisation of aerobic microbial processes, whether these are pure or mixed cultures, and suspended or aggregated cultures. A respirometric method was developed, the multiple concentration pulses method, which allows an exhaustive characterisation of aerobic microbial processes in a short time period, using low cost material and requiring low computational power.Os processos microbianos aeróbios são extremamente importantes em biotecnologia ambiental, nomeadamente nos sistemas biológicos de tratamento de águas residuais onde o processo de lamas activadas representa actualmente a tecnologia mais generalizada de purificação de água. A disponibilidade de ferramentas de monitorização em tempo real confiáveis, baratas e versáteis, que forneçam informações sobre a actividade biológica, é de importância crucial para a monitorização e controlo de processos biológicos, evitando problemas operacionais através da detecção precoce de problemas. Esta tese teve como objectivo desenvolver e aplicar técnicas respirométricas para a determinação de parâmetros cinéticos e estequiométricos em diferentes sistemas com complexidade crescente. O primeiro processo – nitrificação, foi escolhido pela sua simplicidade. Neste processo, o consumo de substrato está relacionado apenas com o crescimento e produção de energia, nenhum fenómeno de armazenamento de substrato ocorre e um método respirométrico in situ foi validado para a determinação de parâmetros cinéticos e estequiométricos em sistemas em estado estacionário: a taxa máxima específica de consumo de oxigénio foi determinada respirometricamente [61.15 (4.09) mg O2 L-1 h-1] através da injecção de pulsos de concentração de substrato crescente; o rendimento de crescimento da biomassa foi estimado a partir de dados respirométricos e a partir do método tradicional de balanço de massa à CQO (Carência Química de Oxigénio) e ambos os métodos deram resultados similares [0.10 (0.07) e 0.09 (0.04) g X-COD g NOD-1, respectivamente]; a constante de afinidade do substrato foi determinada indirectamente após ajuste de um modelo teórico à porção ascendente do respirograma e um valor médio de 0.48 (0.08) mg NH4-N L-1 foi determinado. O ajuste de um modelo foi bem sucedido com uma porção do respirograma, mas não com o respirograma inteiro. Foi concluído que um modelo mais complexo, que tome em consideração os tempos de resposta do eléctrodo e da biomassa, deverá ajustar melhor ao respirograma. Adicionalmente, dois métodos para a determinação do coeficiente volumétrico de transferência de massa do oxigénio foram testados e concluiu-se que o método mais adequado é o método dinâmico. Os resultados obtidos permitiram estabelecer os princípios básicos da metodologia da respirometria de pulsos e o melhor método para determinação do coeficiente volumétrico de transferência de massa do oxigénio. Seguidamente um sistema de cultura pura de Pseudomonas putida foi seleccionado para testar a aplicabilidade da respirometria de pulso numa biomassa com capacidade de armazenar substrato. O modelo ASM3 foi usado para ajuste aos dados experimentais. O modelo incluiu termos que consideravam os tempos de resposta do eléctrodo e da biomassa, assim o respirograma inteiro pôde ser usado para ajuste do modelo. O método respirométrico de pulsos foi validado para a determinação de parâmetros cinéticos e estequiométricos em culturas puras por comparação com o método tradicional de quimiostato, visto que as diferenças dos parâmetros determinados pelos dois métodos não foram significativas: o rendimento em biomass 0.41 (0.05) e 0.51 (0.04) g COD-X g COD-S-1; a constante de afinidade do substrato 4.86 (0.70) e 5.13 (1.99) mg COD-S L-1; a taxa máxima específica de crescimento 0.20 (0.05) e 0.16 (0.01) h-1, com o método do quimiostato e respirométrico, respectivamente. A respirometria de pulso foi depois aplicada a um processo de lamas activadas suspensas alimentado com meio sintético complexo. Nesta etapa, um método respirométrico de pulsos múltiplos foi testado e validado por comparação com o método do quimiostato e com ajuste do modelo ASM1: o rendimento em biomassa estava na gama 0.37 – 0.76 e 0.37 – 0.65 g COD-X g COD-S-1; o coeficiente de manutenção 0.012 (0.012) e 0.010 (0.006) h-1, por balanço mássico de CQO e por respirometria, respectivamente; a constante de afinidade do substrato e a taxa máxima específica de consumo de oxigénio foram determinadas com o método respirométrico de pulsos múltiplos obtendo-se os valores 15.5 (2.4) mg COD-S L-1 e 0.12 (0.01) h-1, respectivamente. Considerando a acessibilidade e comparação dos métodos experimentais e de cálculo, foi concluído que a determinação de parâmetros cinéticos e estequiométricos em culturas mistas aeróbias deve ser preferencialmente feita usando técnicas respirométricas, sendo o método respirométrico de pulsos múltiplos o mais adequado com várias vantagens tais como uma mais simples interpretação dos dados experimentais e obtenção de resultados mais exactos. O método respirométrico de pulsos múltiplos desenvolvido foi finalmente aplicado a um sistema de grânulos aeróbios. O método mostrou ser adequado para determinação de parâmetros neste tipo de sistema e permitiu a monitorização do processo de granulação aeróbia. Num curto tempo e usando equipamento de baixo custo o método permitiu a caracterização exaustiva do processo em tempo real através da determinação de seis parâmetros centrais: (i) rendimento em biomassa; (ii) taxa específica de respiração endógena; (iii) constante de afinidade do substrato; (iv) taxa máxima específica de consumo de oxigénio; (v) taxa máxima específica de consumo de substrato e (vi) taxa máxima específica de crescimento. O método respirométrico de pulsos múltiplos apresentou ainda a vantagem de fornecer parâmetros relacionados com os que realmente estão a ocorrer no sistema sobre as reais condições operacionais, i.e. os parâmetros aparentes, o que é de maior interesse para controlo e operação. Em estado estacionário o rendimento em biomassa foi estimado como sendo de 0.6 g COD-X g COD-S-1, a taxa específica de respiração endógena 0.1 g O2 g COD-X-1 d-1, a constante de afinidade do substrato aproximadamente 20 mg COD-S L-1, a taxa máxima específica de consumo de oxigénio e a taxa máxima específica de consume de substrato 0.06 g O2 g COD-X-1 h-1 e 0.17 g COD-S g COD-X-1 h-1, respectivamente, e a taxa máxima específica de crescimento 2.5 d-1. O potencial do método respirométrico de pulsos múltiplos proposto foi investigado para monitorização de sistemas de grânulos aeróbios e para o controlo eficiente da taxa de arejamento. Adicionalmente, o método respirométrico de pulsos múltiplos foi aplicado a dois sistemas de grânulos aeróbios operados a diferentes taxas de arejamento (5.0 e 6.6 L min-1), permitindo verificar a influência da tensão de corte nos parâmetros cinéticos e estequiométricos: o rendimento em biomassa foi maior na biomassa cultivada na tensão de corte mais alta [0.6 (0.02) versus 0.5 (0.02) g COD-X g COD-S-1 a tensão de corte mais baixa]; a biomassa sujeita a uma tensão de corte mais elevada apresentou uma constante de afinidade do substrato mais alta [16.4 (2.6) e 9.1 (0.2) mg COD-S L-1, a tensão de corte mais alta e mais baixa, respectivamente] e também uma taxa máxima específica de consumo de substrato mais alta [5.4 (0.9) e 2.5 (0.5) g COD-S g COD-X d-1, a tensão de corte mais alta e mais baixa, respectivamente] no fim do processo de granulação aeróbia. A conclusão global retirada desta tese é que a respirometria, especialmente a respirometria de pulsos, é uma técnica válida e promissora para a caracterização cinética e estequiométrica de processos aeróbios, quer sejam culturas puras ou mistas, culturas suspensas ou agregadas. Um método respirométrico foi desenvolvido, o método respirométrico de pulsos múltiplos, que permite a caracterização exaustiva de processos microbianos aeróbios num curto tempo, usando equipamento de baixo custo e requerendo baixo poder computacional

Book of abstracts of the 10th International Chemical and Biological Engineering Conference: CHEMPOR 2008

This book contains the extended abstracts presented at the 10th International Chemical and Biological Engineering Conference - CHEMPOR 2008, held in Braga, Portugal, over 3 days, from the 4th to the 6th of September, 2008. Previous editions took place in Lisboa (1975, 1889, 1998), Braga (1978), Póvoa de Varzim (1981), Coimbra (1985, 2005), Porto (1993), and Aveiro (2001). The conference was jointly organized by the University of Minho, “Ordem dos Engenheiros”, and the IBB - Institute for Biotechnology and Bioengineering with the usual support of the “Sociedade Portuguesa de Química” and, by the first time, of the “Sociedade Portuguesa de Biotecnologia”. Thirty years elapsed since CHEMPOR was held at the University of Minho, organized by T.R. Bott, D. Allen, A. Bridgwater, J.J.B. Romero, L.J.S. Soares and J.D.R.S. Pinheiro. We are fortunate to have Profs. Bott, Soares and Pinheiro in the Honor Committee of this 10th edition, under the high Patronage of his Excellency the President of the Portuguese Republic, Prof. Aníbal Cavaco Silva. The opening ceremony will confer Prof. Bott with a “Long Term Achievement” award acknowledging the important contribution Prof. Bott brought along more than 30 years to the development of the Chemical Engineering science, to the launch of CHEMPOR series and specially to the University of Minho. Prof. Bott’s inaugural lecture will address the importance of effective energy management in processing operations, particularly in the effectiveness of heat recovery and the associated reduction in greenhouse gas emission from combustion processes. The CHEMPOR series traditionally brings together both young and established researchers and end users to discuss recent developments in different areas of Chemical Engineering. The scope of this edition is broadening out by including the Biological Engineering research. One of the major core areas of the conference program is life quality, due to the importance that Chemical and Biological Engineering plays in this area. “Integration of Life Sciences & Engineering” and “Sustainable Process-Product Development through Green Chemistry” are two of the leading themes with papers addressing such important issues. This is complemented with additional leading themes including “Advancing the Chemical and Biological Engineering Fundamentals”, “Multi-Scale and/or Multi-Disciplinary Approach to Process-Product Innovation”, “Systematic Methods and Tools for Managing the Complexity”, and “Educating Chemical and Biological Engineers for Coming Challenges” which define the extended abstracts arrangements along this book. A total of 516 extended abstracts are included in the book, consisting of 7 invited lecturers, 15 keynote, 105 short oral presentations given in 5 parallel sessions, along with 6 slots for viewing 389 poster presentations. Full papers are jointly included in the companion Proceedings in CD-ROM. All papers have been reviewed and we are grateful to the members of scientific and organizing committees for their evaluations. It was an intensive task since 610 submitted abstracts from 45 countries were received. It has been an honor for us to contribute to setting up CHEMPOR 2008 during almost two years. We wish to thank the authors who have contributed to yield a high scientific standard to the program. We are thankful to the sponsors who have contributed decisively to this event. We also extend our gratefulness to all those who, through their dedicated efforts, have assisted us in this task. On behalf of the Scientific and Organizing Committees we wish you that together with an interesting reading, the scientific program and the social moments organized will be memorable for all.Fundação para a Ciência e a Tecnologia (FCT

Degradation of pharmaceuticals in hospital wastewater by solar photo-Fenton processes

The presence of pharmaceuticals in wastewater represents a serious environmental issue that can contribute toward sanitary and health problems. One of the main points behind this matter, is the low efficiency of degradation in conventional wastewater treatment plants (WWTP), or the direct discharge of untreated effluents into water bodies. To overcome this concern, Advanced Oxidation Processes (AOPs) have been widely used due to their generation of highly reactive hydroxyl radicals (HO•), which oxidize the abundant organic contents present in wastewaters. Within AOPs, the Fenton process is widely recognized for its versatility, as there are different ways to produce HO•, facilitating compliance with the specific treatment requirements. The Fenton process is based on the use of iron and hydrogen peroxide for the production of HO• and other radical oxygen species. This process is of particular interest, as sunlight can be used to improve its efficiency in removing emerging pollutants. Despite this, more research is still needed for its application in large scale wastewater treatment. This study was subsequently developed to evaluate different operational strategies of solar photo- Fenton to remove pharmaceuticals in hospital wastewater. To achieve this goal, the solar photo-Fenton processes were studied using Fe0, Fe2+/3+-alginate and Fe3+:EDDS under optimized experimental conditions. In addition, analytical monitoring of treatment processes, identification of transformation products (TPs) using LC-QTOF MS, coupled with the use of a purpose-designed database and toxicological/biodegradable predictions using (Q)SAR tools were performed in this research. A batch reactor (1L) and a raceway pond reactor (10 L) made with low-cost materials were operated at pH close to neutrality. Additionally, three types of wastewater were worked on: distilled water (DW), simulated wastewater (SWW) and raw hospital wastewater (RHWW) fortified with a mixture of pharmaceuticals (Dipyrone-DIP, Diazepam-DZP, Fluoxetine-FXT, Furosemide-FRS, Gemfibrozil-GFZ, Nimesulide- NMD and Progesterone-PRG) as a model of micropollutants with different initial concentrations (500 μg L-1 and 50 μg L-1), then treated by the solar processes mentioned above. The experiments being carried out on sunny days at noon, the measured solar UV radiation was used to calculate t30W, which allows the comparison of solar experiments carried out on different days, months and seasons throughout the year. 5 The systems with Fe0 and Fe3+:EDDS showed rapid degradation of the pharmaceuticals in a reaction time of less than 60 minutes.Fe3+ immobilized in alginate was the most efficient strategy for a constant supply of iron into the solution with a consecutive reuse capacity of 3 times. The total consumption of H2O2 was observed in SWW and RHWW for all systems, and the final concentrations of dissolved iron are in accordance with the maximum level allowed by Brazilian legislation (<15 mg L-1). The raceway pond reactor was used with Fe3+:EDDS on a larger scale (10L), with the results demonstrating the best efficacy in Fe3+:EDDS (1:2) for the degradation of pharmaceuticals within a short time-frame. Moreover, a more specific study of the TPs generated and degradation pathway proposals, using different proportions of iron and complexing agent, was performed. Furthermore, in an additional study, the use of an App (PhotoMetrix PRO®) for the quantification of H2O2 and Fe species, in loco, was successfully validated. Finally, the use of different operational strategies of solar photo-Fenton proved to be efficient in the removal of pharmaceuticals and, in some cases, also that of their transformation products at circumneutral pH in simulated and hospital wastewater. In most cases, during the solar treatments, TPs showed high to moderate toxicity and persistence, but throughout the process(es), these TPs are converted to simpler and less harmful structures. At the same time, the treatments tested presented advantages and disadvantages, such as environmental or economic issues related to the reagents used and the TPs generated, among others. Nevertheless, this research highlights the need for further studies in the area of wastewater treatment using sunlight and real wastewater matrices.A presença de fármacos em águas residuais representa um grave problema ambiental que pode contribuir como um dos fatores de problemas sanitários e de saúde pública. Um dos principais fatores, além da frequência dos fármacos no meio ambiente, é a baixa eficiência de degradação destes em sistemas de tratamento convencionalmente empregados para águas residuais. Para superar esse problema, muitos estudos têm focado sua atenção no uso dos Processos Avançados de Oxidação (PAOs) para alcançar a oxidação de diferentes microcontaminantes mediante a geração, majoritariamente, de radicais hidroxila (HO•), os quais são espécies altamente reativas. Dentro dos PAOs, o processo Fenton é amplamente reconhecido por sua versatilidade, pois existem diferentes formas de produção de HO•, facilitando o cumprimento dos requisitos específicos de tratamento. O processo Fenton é baseado na utilização de ferro e peróxido de hidrogênio para a produção de HO• e outras espécies de oxigênio radicais. Este processo é de particularmente interessante, pois a luz solar pode ser usada para melhorar sua eficiência na remoção de contaminantes emergentes. No entanto, ainda são necessários mais estudos para sua aplicação no tratamento de águas residuais em larga escala. Este estudo foi desenvolvido para avaliar diferentes estratégias operacionais do processo foto-Fenton solar para viabilizar a remoção de fármacos em matrizes como é o caso de efluentes hospitalares. Para este fim, os processos foto-Fenton solares foram estudados usando Fe0, Fe2+/3+-alginato e Fe3+:EDDS em condições experimentais otimizadas. Da mesma forma, o acompanhamento analítico dos processos, a identificação de produtos de transformação (TPs) mediante LC-QTOF MS e o uso de uma base de dados especialmente elaborada para essa finalidade acoplado com a predição toxicológica e da biodegradabilidade empregando ferramentas de análise de risco in sílico ((Q)SAR) foram empregados nesta tese. Um reator de batelada em escala de laboratório (1L) e um reator “raceway pond” (10 L) feito com materiais de baixo custo foram operados na maioria das experiências em pH próximo á neutralidade. Adicionalmente, foram avaliadas três matrizes aquosas: água destilada (DW), efluente simulado (SWW) e efluente hospitalar real (RHWW) fortificadas com uma mistura de fármacos (Dipirona-DIP, Diazepam-DZP, Fluoxetina- FXT, Furosemida-FRS, Genfibrozila-GFZ, Nimesulida-NMD e Progesterona-PRG), 7 como micropoluentes modelo, em diferentes concentrações iniciais (500 μg L-1 e 50 μg L-1). Em seguida, tais soluções foram tratadas pelos processos destacados anteriormente. Os experimentos foram realizados em dias de sol ao meio-dia, a radiação UV medida foi utilizada para calcular t30W, a qual permite a comparação de experimentos solares realizados em diferentes dias, meses e estações ao longo do ano. Os sistemas com Fe0 e Fe3+:EDDS apresentaram rápida degradação dos fármacos em um tempo de reação inferior a 60 minutos. Fe3+ imobilizado em alginato foi a estratégia mais eficiente para um fornecimento constante de ferro na solução com uma capacidade de reutilização consecutiva de 3 vezes. O consumo total do H2O2 foi atingido para matrizes como SWW e RHWW em todos os processos, e os níveis finais de ferro dissolvido estão em acordo com o nível máximo permitido pela legislação Brasileira (< 15 mg L-1). O reator do tipo “raceway pond” foi utilizado com Fe3+:EDDS em escala superior (10 L). Os resultados demonstram a eficácia do complexo de Fe3+:EDDS (1:2) para a degradação de fármacos em um pequeno tempo de tratamento, bem como, um estudo mais específico dos TPs gerados usando diferentes proporções de ferro e agente complexante. Adicionalmente, foi validado com sucesso o uso de um aplicativo (PhotoMetrix PRO) para a quantificação, in loco, de H2O2 e Fe. Finalmente, as diferentes estratégias operacionais do foto-Fenton solar mostraram-se eficientes na remoção de fármacos e, em alguns casos, também para seus TPs empregando pH próximo à neutralidade, tanto em SWW quanto em RHWW. Na maioria dos casos, os TPs apresentaram toxidade classificada como alta a moderada e persistência no ambiente. Porém, ao longo do(s) processo(s), tais TPs são convertidos a estruturas mais simples e menos nocivas. Ao mesmo tempo, os diferentes tipos de tratamentos testados apresentaram vantagens e desvantagens, como questões ambientais ou econômicas relacionadas aos reagentes utilizados e aos TPs gerados, dentre outros fatores. Por outro lado, ressalta-se a necessidade de estudos adicionais na área de tratamento de efluentes usando luz solar e matrizes reais

Mechanistic understanding of mixed-culture fermentations by metabolic modelling

Biorefineries are set to become an important agent in the shift towards a circular economy due to their potential to valorise organic wastes into marketable products. Anaerobic fermentations yielding volatile fatty acids are a key process in this production scheme as their products act as intermediates between the organic wastes and the final biorefinery products. However, their product selectivity is highly influenced by the environmental conditions and the mechanisms governing the process remain unknown. In this thesis, predictive tools were developed with the objective of understanding the mechanisms governing anaerobic fermentations and of designing processes targeting specific volatile fatty acids with high productivity

Continuous Biochemical Processing: Investigating Novel Strategies to Produce Sustainable Fuels and Pharmaceuticals

Biochemical processing methods have been targeted as one of the potential renewable strategies for producing commodities currently dominated by the petrochemical industry. To design biochemical systems with the ability to compete with petrochemical facilities, inroads are needed to transition from traditional batch methods to continuous methods. Recent advancements in the areas of process systems and biochemical engineering have provided the tools necessary to study and design these continuous biochemical systems to maximize productivity and substrate utilization while reducing capital and operating costs. The first goal of this thesis is to propose a novel strategy for the continuous biochemical production of pharmaceuticals. The structural complexity of most pharmaceutical compounds makes chemical synthesis a difficult option, facilitating the need for their biological production. To this end, a continuous, multi-feed bioreactor system composed of multiple independently controlled feeds for substrate(s) and media is proposed to freely manipulate the bioreactor dilution rate and substrate concentrations. The optimal feed flow rates are determined through the solution to an optimal control problem where the kinetic models describing the time-variant system states are used as constraints. This new bioreactor paradigm is exemplified through the batch and continuous cultivation of β-carotene, a representative product of the mevalonate pathway, using Saccharomyces cerevisiae strain mutant SM14. The second goal of this thesis is to design continuous, biochemical processes capable of economically producing alternative liquid fuels. The large-scale, continuous production of ethanol via consolidated bioprocessing (CBP) is examined. Optimal process topologies for the CBP technology selected from a superstructure considering multiple biomass feeds, chosen from those available across the United States, and multiple prospective pretreatment technologies. Similarly, the production of butanol via acetone-butanol-ethanol (ABE) fermentation is explored using process intensification to improve process productivity and profitability. To overcome the inhibitory nature of the butanol product, the multi-feed bioreactor paradigm developed for pharmaceutical production is utilized with in situ gas stripping to simultaneously provide dilution effects and selectively remove the volatile ABE components. Optimal control and process synthesis techniques are utilized to determine the benefits of gas stripping and design a butanol production process guaranteed to be profitable