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Abstract(s)
Nos últimos anos, têm sido detetadas várias classes de fármacos em águas superficiais. Embora a sua concentração esteja na ordem dos ng/L e µg/L, a sua presença no ambiente é considerado um problema de caráter emergente. Isto deve-se principalmente ao facto de as estações de tratamento de águas residuais não terem sido projetadas para a remoção deste tipo de contaminantes, tornando-se necessário desenvolver tratamentos complementares que sejam sustentáveis e económicos. A presente dissertação teve como objetivo o estudo da remoção de fluoxetina (FLX), um dos antidepressivos mais consumidos a nível mundial, utilizando um biomaterial – substrato colonizado com Pleurotus ostreatus. Foram realizados ensaios em sistema fechado (50 g de substrato colonizado, concentração inicial de FLX 600 µg/L, pH 7, 20-25 ºC) para estudar a contribuição dos vários mecanismos de remoção, nomeadamente, oxidação por enzimas extracelulares, degradação intracelular pelo citocromo P450 (CP450) e sorção. Concluiu-se que a participação do CP450 foi negligenciável e que a sorção foi responsável por 45% da remoção do fármaco. Além disso, verificou-se que a remoção abiótica foi cerca de 8%. A remoção total de FLX foi alcançada num ensaio utilizando substrato colonizado sem qualquer tratamento prévio, salientando a contribuição das enzimas extracelulares e do mecanismo de sorção. Pelo contrário, nos ensaios com extratos enzimáticos, realizados em sistema fechado (concentração inicial de FLX 600 µg/L, pH 6 e 7, 24-25 ºC) removeuse apenas 22% do fármaco, sendo considerados pouco eficazes. No ensaio em contínuo (coluna de leito fixo, 12 g de substrato colonizado, concentração inicial de FLX 600 µg/L, pH 7, 23-26 ºC), verificou-se a remoção total durante os primeiros 20 min, sendo a remoção superior a 70% no tempo restante de experiência. A utilização de substrato colonizado permitiu remover completamente a FLX em ambos os ensaios (sistema fechado e em contínuo), demonstrando o seu potencial na descontaminação de águas. Apesar de apresentar inúmeras vantagens, a sua implementação em larga escala enfrenta ainda muitos desafios.
In the last years, different classes of pharmaceuticals have been detected in surface waters. Even though they are found in the concentration of ng/L and ug/L, their presence in the environment is considered an emergent problem. It may be attributed to the fact that wastewater treatment plants have not been designed for the removal of this type of contaminant, becoming necessary to develop complementary treatments that should be sustainable and economical. The present dissertation aim was to study the removal of fluoxetine (FLX), one of the most consumed antidepressants in the world, using a biomaterial – colonized substrate with Pleurotus ostreatus. The batch assays (50 g of colonized substrate, initial concentration of FLX 600 µg/L, pH 7, 20-25 ºC) were carried out to study the contribution of the different mechanisms of removal, namely, extracellular enzymes oxidation, intracellular degradation by cytochrome P450 (CP450) and sorption. It was concluded that the participation of CP450 was negligible, and the sorption was responsible for 45% of the pharmaceutical removal. Furthermore, the abiotic removal was about 8%. The complete removal of FLX was achieved in an experiment using colonized substrate without any previous treatment, highlighting the contribution of extracellular enzymes and the sorption mechanism. On the other hand, the crude enzyme assays carried out in batch system (initial concentration of FLX 600 µg/L, pH 6 e 7, 24-25 ºC) removed only 22% of FLX, being considered less effective. In the continuous assay (fixed-bed column, 12 g of colonized substrate, initial concentration of FLX 600 µg/L, pH 7, 23-26 ºC), the total removal was achieved during the first 20 min, being higher than 70% in the remaining time of experience. The use of colonized substrate allowed the complete removal of FLX in both assays (batch system and in continuous), demonstrating its potential in the decontamination of waters. Although it has many advantages, its large-scale implementation faces several challenges yet.
In the last years, different classes of pharmaceuticals have been detected in surface waters. Even though they are found in the concentration of ng/L and ug/L, their presence in the environment is considered an emergent problem. It may be attributed to the fact that wastewater treatment plants have not been designed for the removal of this type of contaminant, becoming necessary to develop complementary treatments that should be sustainable and economical. The present dissertation aim was to study the removal of fluoxetine (FLX), one of the most consumed antidepressants in the world, using a biomaterial – colonized substrate with Pleurotus ostreatus. The batch assays (50 g of colonized substrate, initial concentration of FLX 600 µg/L, pH 7, 20-25 ºC) were carried out to study the contribution of the different mechanisms of removal, namely, extracellular enzymes oxidation, intracellular degradation by cytochrome P450 (CP450) and sorption. It was concluded that the participation of CP450 was negligible, and the sorption was responsible for 45% of the pharmaceutical removal. Furthermore, the abiotic removal was about 8%. The complete removal of FLX was achieved in an experiment using colonized substrate without any previous treatment, highlighting the contribution of extracellular enzymes and the sorption mechanism. On the other hand, the crude enzyme assays carried out in batch system (initial concentration of FLX 600 µg/L, pH 6 e 7, 24-25 ºC) removed only 22% of FLX, being considered less effective. In the continuous assay (fixed-bed column, 12 g of colonized substrate, initial concentration of FLX 600 µg/L, pH 7, 23-26 ºC), the total removal was achieved during the first 20 min, being higher than 70% in the remaining time of experience. The use of colonized substrate allowed the complete removal of FLX in both assays (batch system and in continuous), demonstrating its potential in the decontamination of waters. Although it has many advantages, its large-scale implementation faces several challenges yet.
Description
Keywords
Biorremediação Fluoxetina Lacase Pleurotus ostreatus Sorção Bioremediation Fluoxetine Laccase Pleurotus ostreatus Sorption