A carregar...
Publicação
Avaliação da eficiência de remoção de Diclofenac da água utilizando Lamas provenientes de Es- tação de Tratamento de Água
| Nome: | Descrição: | Tamanho: | Formato: | |
|---|---|---|---|---|
| 2.17 MB | Adobe PDF |
Orientador(es)
Resumo(s)
A presença de poluentes de preocupação emergente (PPE) no ambiente, especialmente nos ecossistemas
aquáticos têm gerado uma preocupação crescente, principalmente, junto da comunidade científica. A
presença em ambientes aquáticos de compostos como o Diclofenac (DCF), anti-inflamatório utilizado
no tratamento de inflamações em humanos e animais, pode ter consequências graves para organismos
aquáticos, mas também, potencialmente, para a saúde humana. As estações de tratamento de águas re-
siduais (ETAR) são consideradas um dos principais pontos de entrada de DCF no ambiente, uma vez
que os métodos convencionais de tratamento de água residual não são capazes, nem foram concebidos
para remover este composto. Torna-se, por isso, importante estudar sistemas de tratamento complemen-
tares para a remoção deste composto, especialmente, com o aumento do incentivo à reutilização de águas
residuais tratadas promovido nos Objetivos para o Desenvolvimento Sustentável (ODS) das Nações
Unidas.
Dos diversos tratamentos complementares que possibilitam a remoção de PPE, os processos de adsorção
são considerados dos mais promissores devido a sua elevada eficiência na remoção deste tipo de conta-
minantes e facilidade de operação, possibilidade de recuperação e reutilização de resíduos, e/ou subpro-
dutos reduzida formação de subprodutos, para além de ser uma tecnologia ambientalmente sustentável
pois necessita de menos energia quando comparado com outros sistemas de tratamento complementares,
como é o caso das membranas.
Os adsorventes de baixo custo têm sido estudados para a remoção de PPE, pois, para além de terem
ainda capacidade de utilização para este uso, podem constituir soluções eficazes para a gestão de resí-
duos e remediação ambiental, e ainda serem economicamente vantajosos. As lamas das estações de
tratamento de água (LETA) têm vindo a ser referidas como um possível material adsorvente devido as
suas características físico-químicas, tendo já sido reportada a sua capacidade para a remoção de metais
pesados e nutrientes. Contudo, a sua utilização na remoção de PPE ainda não foi suficientemente estu-
dada, verificando-se a necessidade de desenvolver mais estudos que permitam compreender os meca-
nismos de adsorção responsáveis pela adsorção de PPE.
A presente dissertação teve como objetivo a avaliação da utilização de LETA como adsorvente de DCF.
Para esse efeito procedeu-se à realização de ensaios de massa, de estudos de cinética e de isotérmicas
de adsorção com recurso a uma LETA previamente caracterizada. Através de ensaios de massa, foi
possível identificar que a concentração ideal de lamas para remoção de DCF foi de 1 g/L, pois esta
concentração apesar de apresentar menor eficiência de remoção quando comparado com a concentração
de 2 g/L, apresentou uma melhor capacidade de adsorção. Os resultados obtidos no ensaio de cinética
mostraram que o equilíbrio foi alcançado próximo das 24 horas. Com base nos resultados do ensaio de
cinética foi possível verificar que o modelo de pseudo-segunda ordem foi o que melhor explicou o pro-
cesso de adsorção (R2 de 0,9888). Dos modelos isotérmicos avaliados, o modelo de Langmuir foi o que
melhor descreveu os dados experimentais com uma capacidade máxima de adsorção de 18,44 mg/g.
Estes resultados evidenciaram uma nova abordagem na gestão deste outrora resíduo contribuindo desta
forma para a economia circular no sector do tratamento da água, assim como, e uma forma sustentável,
de remoção de PPE.
The presence of emerging concern pollutants (ECP) in the environment, particularly in aquatic ecosys- tems, has raised increasing concerns, especially among the scientific community. The occurrence of compounds such as Diclofenac (DCF), a non-steroidal anti-inflammatory drug used to treat inflamma- tion in humans and animals, in aquatic environments can have serious consequences for aquatic organ- isms and potentially for human health as well. Wastewater treatment plants are considered one of the primary sources of DCF into the environment, as conventional wastewater treatment systems are neither capable nor designed to remove this compound. Therefore, it is essential to study complementary treat- ment systems for the removal of DCF, especially in light of the growing emphasis on wastewater reuse promoted by the United Nations Sustainable Development Goals (SDGs). Among the complementary treatments available for the removal of ECP, the adsorption process is high- lighted as one of the most promising due to its high efficiency in eliminating such contaminants, ease of operation, potential for recovery and reuse of waste produced, and minimal to no formation of by- products. Moreover, this treatment is environmentally friendly, as it requires less energy than other complementary treatment systems, such as membrane technologies. Extensive research has been con- ducted on low-cost adsorbents for the removal of emerging pollutants, as they have been showing ca- pacity for the removal of these compounds. Additionally, these adsorbents can offer effective solutions for waste management and environmental remediation while also providing economic benefits. The sludge from drinking water treatment plants (DWTP) has been identified as a potential adsorbent mate- rial due to its physico-chemical characteristics, and its capacity for removing heavy metals and nutrients has already been documented. Nonetheless, the application of this method to remove emerging pollu- tants has not been adequately studied, underscoring the necessity for further research to comprehend the adsorption mechanisms involved in the elimination of these pollutants. This dissertation aimed to evaluate the use of DWTP sludge as an adsorbent for DCF. To this end, mass tests, kinetic studies, and adsorption isotherm studies were performed using DWTP sludge previously characterised. Mass tests revealed that the optimal sludge concentration for DCF removal was 1 g/L; although this concentration showed lower removal efficiency than 2 g/L, it exhibited a better adsorption capacity. The results obtained from the kinetic study showed that equilibrium was reached around 24 hours. According to the results of the kinetic study, the pseudo-second-order model was found to best describe the adsorption process (R² = 0.9888). Among the evaluated isotherm models, the Langmuir model showed the best fit for the experimental data, with a maximum adsorption capacity of 18.44 mg/g. These results highlight a novel approach to DWTP sludge management, thereby promoting the circular economy in the water treatment sector and providing a sustainable method for the removal of emerging concern pollutants.
The presence of emerging concern pollutants (ECP) in the environment, particularly in aquatic ecosys- tems, has raised increasing concerns, especially among the scientific community. The occurrence of compounds such as Diclofenac (DCF), a non-steroidal anti-inflammatory drug used to treat inflamma- tion in humans and animals, in aquatic environments can have serious consequences for aquatic organ- isms and potentially for human health as well. Wastewater treatment plants are considered one of the primary sources of DCF into the environment, as conventional wastewater treatment systems are neither capable nor designed to remove this compound. Therefore, it is essential to study complementary treat- ment systems for the removal of DCF, especially in light of the growing emphasis on wastewater reuse promoted by the United Nations Sustainable Development Goals (SDGs). Among the complementary treatments available for the removal of ECP, the adsorption process is high- lighted as one of the most promising due to its high efficiency in eliminating such contaminants, ease of operation, potential for recovery and reuse of waste produced, and minimal to no formation of by- products. Moreover, this treatment is environmentally friendly, as it requires less energy than other complementary treatment systems, such as membrane technologies. Extensive research has been con- ducted on low-cost adsorbents for the removal of emerging pollutants, as they have been showing ca- pacity for the removal of these compounds. Additionally, these adsorbents can offer effective solutions for waste management and environmental remediation while also providing economic benefits. The sludge from drinking water treatment plants (DWTP) has been identified as a potential adsorbent mate- rial due to its physico-chemical characteristics, and its capacity for removing heavy metals and nutrients has already been documented. Nonetheless, the application of this method to remove emerging pollu- tants has not been adequately studied, underscoring the necessity for further research to comprehend the adsorption mechanisms involved in the elimination of these pollutants. This dissertation aimed to evaluate the use of DWTP sludge as an adsorbent for DCF. To this end, mass tests, kinetic studies, and adsorption isotherm studies were performed using DWTP sludge previously characterised. Mass tests revealed that the optimal sludge concentration for DCF removal was 1 g/L; although this concentration showed lower removal efficiency than 2 g/L, it exhibited a better adsorption capacity. The results obtained from the kinetic study showed that equilibrium was reached around 24 hours. According to the results of the kinetic study, the pseudo-second-order model was found to best describe the adsorption process (R² = 0.9888). Among the evaluated isotherm models, the Langmuir model showed the best fit for the experimental data, with a maximum adsorption capacity of 18.44 mg/g. These results highlight a novel approach to DWTP sludge management, thereby promoting the circular economy in the water treatment sector and providing a sustainable method for the removal of emerging concern pollutants.
Descrição
Palavras-chave
Tratamento de Água Adsorção Diclofenac Lamas das Estações de Tratamento de Água Reutilização Economia circular