Microalgae technology: sustainable transformation of emerging pollutants

Tese no âmbito de Doutoramento em Química, ramo de Fotoquímica e apresentada ao Departamento de Química da Faculdade de Ciências e Tecnologia da Universidade de Coimbra.Os efeitos adversos das actividades humanas têm levado à contaminação da água por uma gama cada vez mais complexa de poluentes emergentes. Estes não são eliminados pelos métodos convencionais de tratamento de água e, através do ciclo hidrológico urbano, podem entrar em águas subterrâneas e superficiais, persistir no meio ambiente, bioacumular-se através da cadeia alimentar e chegar à água potável. Incluem-se nos poluentes emergentes fármacos, pesticidas, plastificantes e vários outros grupos de contaminantes; são revistos nesta tese, alguns dos mais relevantes. A combinação de diferentes tecnologias de tratamento de água pode reduzir significativamente a ocorrência de poluentes no ambiente aquático, diminuindo a exposição aos contaminantes e consequentes condições médicas associadas, levando a uma melhoria da saúde e bem-estar. Esta tese aborda a necessidade de uma solução para o problema da poluição da água. Propõe a descontaminação de águas residuais recorrendo a microalgas, com uma abordagem baseada na geração de biomassa e na sua valorização económica, através de potenciais produtos de valor acrescentado. Esses produtos podem atrair investimentos na tecnologia e, portanto, acelerar o seu desenvolvimento. Em primeiro lugar, avaliou-se a eficácia e eficiência do uso de microalgas na biorremediação de substâncias químicas sintéticas. Foram selecionados para o estudo os fármacos mais frequentemente detectados no ambiente e um representante do principal grupo de pesticidas, caracterizado pela sua toxicidade em insectos benéficos e pela exposição a que está sujeita a população em geral. Subsequentemente, avaliou-se a viabilidade da transformação de biomassa proveniente da biorremediação em produtos ecológicos inovadores. Paralelamente, diferentes métodos analíticos foram optimizados e desenvolvidos para a análise e avaliação de processos e produtos. Dentre estes, destaque-se o desenvolvimento de um método simples e confiável com resposta rápida para detecção e quantificação de lípidos, combinando uma nova sonda fluorescente altamente lipofílica, BODIPY BD-C12, e análise de imagem para determinar o conteúdo lipídico de algas e a produção de lípidos na microalga Nannocloropsis sp .. Os estudos de biorremediação revelaram que a microalga marinha Nannochloropsis sp. remove paracetamol, ibuprofeno, olanzapina, sinvastatina e imidacloprida, apresentando diferentes eficiências. A remoção do paracetamol e ibuprofeno foi significativamente maior em células imobilizadas em álcool polivinílico do que em células livres, após as primeiras 24 horas de cultura. No grupo das células livres, a remoção de olanzapina revelou maior eficiência, sugerindo uma maior afinidade das células à molécula de olanzapina do que ao paracetamol e ibuprofeno. Os estudos de imobilização das células mostraram que, embora o álcool polivinílico seja considerado biocompatível, este inibe a proliferação celular. Experiências com o polímero mostraram a libertação de células das esferas e sua desintegração devido à dissolução do álcool polivinílico. Após o processo de biorremediação, a produção de produtos específicos foi avaliada e otimizada; com a otimização das condições, foi possível alcançar um elevado rendimento de 74% do teor de lípidos na espécie Nannochloropsis sp. e, com as partes restantes das células, foi possível demonstrar a sua aplicação em produtos ópticos avançados. Estes encontram aplicações em lentes oftálmicas, que podem ser usadas em óculos graduados e de sol, tendo potencial para ser a primeira lente verde no mercado. Este estudo fornece um importante primeiro passo na tecnologia de biorremediação recorrendo a microalgas, um entendimento sobre a viabilidade da sustentabilidade num conceito de biorrefinaria de microalgas, com base na economia circular.Adverse effects of human activity are leading to water contamination by an increasingly complex range of emerging pollutants, which are not readily treated by conventional means, and, through the urban water cycle, can enter ground and surface waters, can persist in the environment, bioaccumulate through the food chain and reach drinking water. These include pharmaceuticals, pesticides, plasticisers and several other groups of contaminants. Some of these compounds are reviewed in this thesis. The combination of different water treatment technologies could significantly reduce the occurrence of pollutants in the aquatic environment, which leads to an improvement of health and well-being by preventing exposure to chemicals and the related diseases arising from contaminated water. This thesis addresses the need for a solution to the problem of treatment of emerging pollutants, and proposes the decontamination of wastewaters using microalgae, with an approach based on the generation of biomass, and on the respective economic valorization. It aims to study the potential of obtaining high value-added products that could attract investment in this field and therefore, accelerate the development of microalgae technology. In the first part of the Thesis, the effectiveness and efficiency of using microalgae in the bioremediation of synthetic chemicals were evaluated. The most frequent pharmaceuticals detected in the environment, and a representative of the major group of pesticides, were selected for the study, based on their respective toxicity to beneficial insects and ubiquitous exposure of the general population. The second stage assessed the feasibility of the transformation of the biomass from bioremediation into innovative bio-based products. In parallel, various methods were optimised and developed for the analysis and evaluation of processes and products. Of these, the most significant one is a simple reliable method with fast response for lipid detection and quantification, combining a new highly lipophilic fluorescent probe BODIPY BD-C12 and image analysis to determine the algal lipid content and the lipid production in the microalga Nannochloropsis sp.. The bioremediation experiments revealed that the marine microalga Nannochloropsis sp. removes the pollutants paracetamol, ibuprofen, olanzapine, simvastatin and imidacloprid with different efficiencies. The removal of paracetamol and ibuprofen after the first 24 hours of culture was significantly higher in polyvinyl alcohol immobilised cells than in free cells. In the group of free cells, the removal of olanzapine revealed a higher efficiency, suggesting more affinity of cells to the molecule of olanzapine than to paracetamol and ibuprofen. The immobilisation experiments showed that, although polyvinyl alcohol is considered to be biocompatible, it inhibits cell proliferation. Also, experiments with the polymer showed the leakage of cells from the beads, and its disintegration due to dissolution of polyvinyl alcohol. After the bioremediation process, the formation of specific products was assessed, and with the optimisation of the conditions it was possible to achieve a high yield of 74 % of lipid content in Nannochloropsis sp. and, with the remaining parts of the cells, it was possible to demonstrate the application of products from microalgae bioremediation in advanced optical products. These find applications in ophthalmic lenses, which can be used on prescription glasses and sunglasses, having potential to be the first green lens in the market. This study provides an important first step in bioremediation using microalgae, and an understanding toward the feasibility and sustainability of the microalgae biorefinery concept, based on the circular economy.Fundação para a Ciência e a Tecnologia (FCT

Bioplastics: Innovation for Green Transition

Bioplastics are one of the possible alternative solutions to the polymers of petrochemical origins. Bioplastics have several advantages over traditional plastics in terms of low carbon footprint, energy efficiency, biodegradability and versatility. Although they have numerous benefits and are revolutionizing many application fields, they also have several weaknesses, such as brittleness, high-water absorption, low crystallization ability and low thermal degradation temperature. These drawbacks can be a limiting factor that prevents their use in many applications. Nonetheless, reinforcements and plasticizers can be added to bioplastic production as a way to overcome such limitations. Bioplastics materials are not yet studied in depth, but it is with great optimism that their industrial use and market scenarios are increasing; such growth can be a positive driver for more research in this field. National and international investments in the bioplastics industry can also promote the green transition. International projects, such as EcoPlast and Animpol, aim to study and develop new polymeric materials made from alternative sources. One of their biggest problems is their waste management; there is no separation process yet to recycle the nonbiodegradable bioplastics, and they are considered contaminants when mixed with other polymers. Some materials use additives, and their impact on the microplastics they leave after breaking apart is subject to debate. For this reason, it is important to consider their life cycle analysis and assess their environmental viability. These are materials that can possibly be processed in various ways, including conventional processes used for petrochemical ones. Those include injection moulding and extrusion, as well as digital manufacturing. This and the possibility to use these materials in several applications is one of their greatest strengths. All these aspects will be discussed in this review

Removal of Pharmaceuticals from Water by Free and Imobilised Microalgae

Pharmaceuticals and their metabolites are released into the environment by domestic, hospital, and pharmaceutical industry wastewaters. Conventional wastewater treatment technology does not guarantee effluents of high quality, and apparently clean water may be loaded with pollutants. In this study, we assess the performance and efficiency of free and immobilised cells of microalgae Nannochloropsis sp. in removing four pharmaceuticals, chosen for their occurrence or persistence in the environment. These are paracetamol, ibuprofen, olanzapine and simvastatin. The results showed that free microalgae cells remain alive for a longer time than the immobilised ones, suggesting the inhibition of cell proliferation by the polymeric matrix polyvinyl alcohol. Both cells, free and immobilised, respond differently to each pharmaceutical. The removal of paracetamol and ibuprofen by Nannochloropsis sp., after 24 h of culture, was significantly higher in immobilised cells. Free cells removed a significantly higher concentration of olanzapine than immobilised ones, suggesting a higher affinity to this molecule than to paracetamol and ibuprofen. The results demonstrate the effectiveness of Nannochloropsis sp. free cells for removing olanzapine and Nannochloropsis sp. immobilised cells for removing paracetamol and ibuprofen

Removal of Pharmaceuticals from Water by Free and Imobilised Microalgae

Pharmaceuticals and their metabolites are released into the environment by domestic, hospital, and pharmaceutical industry wastewaters. Conventional wastewater treatment technology does not guarantee effluents of high quality, and apparently clean water may be loaded with pollutants. In this study, we assess the performance and efficiency of free and immobilised cells of microalgae Nannochloropsis sp. in removing four pharmaceuticals, chosen for their occurrence or persistence in the environment. These are paracetamol, ibuprofen, olanzapine and simvastatin. The results showed that free microalgae cells remain alive for a longer time than the immobilised ones, suggesting the inhibition of cell proliferation by the polymeric matrix polyvinyl alcohol. Both cells, free and immobilised, respond differently to each pharmaceutical. The removal of paracetamol and ibuprofen by Nannochloropsis sp., after 24 h of culture, was significantly higher in immobilised cells. Free cells removed a significantly higher concentration of olanzapine than immobilised ones, suggesting a higher affinity to this molecule than to paracetamol and ibuprofen. The results demonstrate the effectiveness of Nannochloropsis sp. free cells for removing olanzapine and Nannochloropsis sp. immobilised cells for removing paracetamol and ibuprofen

Development and validation of a RP-HPLC method for the simultaneous analysis of paracetamol, ibuprofen, olanzapine, and simvastatin during microalgae bioremediation

A rapid reverse phase high-performance liquid chromatography (RP-HPLC) method was developed and validated for the simultaneous quantification of paracetamol, ibuprofen, olanzapine, simvastatin and simvastatin acid in the context of microalgae bioremediation. The method was validated according to the guidelines of the US Food and Drug Administration (FDA), the International Conference on Harmonization (ICH), and Eurachem with respect to system suitability, linearity, accuracy, precision, recovery, limits of detection and quantification, ruggedness, selectivity and specificity. The estimated limits of detection and quantification were, respectively, 0.03 and 0.10 µg mL-1 for paracetamol, 0.03 and 0.09 µg mL-1 for ibuprofen, 0.04 and 0.13 µg mL-1 for olanzapine, 0.27 and 0.83 µg mL-1 for simvastantin, and 0.05 and 0.14 µg mL-1 for simvastantin acid. The inter-day and intra-day precision results were within the acceptance limit of relative standard deviation (%RSD) of less than 2, and the percentage recovery was found to be within the required limits of 80-110%. The developed method is rapid, linear, precise, robust and accurate, and has been successfully applied to the determination of the above common pharmaceutical products during microalgae bioremediation