Browsing by Author "Santos, Ana"
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- Biodegradation rate constants in different NF/UF fractions of cork processing wastewatersPublication . Bernardo, Marisa; Santos, Ana; Cantinho, Paula; Minhalma, MiguelCork processing wastewater is an aqueous complex mixture of organic compounds that have been extracted from cork planks during the boiling process. These compounds, such as polysaccharides and polyphenols, have different biodegradability rates, which depend not only on the natureof the compound but also on the size of the compound. The aim of this study is to determine the biochemical oxygen demands (BOD) and biodegradationrate constants (k) for different cork wastewater fractions with different organic matter characteristics. These wastewater fractions were obtained using membrane separation processes, namely nanofiltration (NF) and ultrafiltration (UF). The nanofiltration and ultrafiltration membranes molecular weight cut-offs (MWCO) ranged from 0.125 to 91 kDa. The results obtained showed that the biodegradation rate constant for the cork processing wastewater was around 0.3 d(-1) and the k values for the permeates varied between 0.27-0.72 d(-1), being the lower values observed for permeates generated by the membranes with higher MWCO and the higher values observed for the permeates generated by the membranes with lower MWCO. These higher k values indicate that the biodegradable organic matter that is permeated by the membranes with tighter MWCO is more readily biodegradated.
- Cork industry wastewater characterization assessment of the biodegradability, reuse and of the relationship between BOD, COD and tannins with TOCPublication . Santos, Ana; Bernardo, Marisa; Vespeira, Carla; Cantinho, Paula; Minhalma, MiguelCork processing involves a boiling step to make the cork softer, which consumes a high volume of water and generates a wastewater with a high organic content, rich in tannins. An assessment of the final wastewater characteristics and of the boiling water composition along the boiling process was performed. The parameters studied were pH, color, total organic carbon (TOC), chemical and biochemical oxygen demands (COD, BOD5, BOD20), total suspended solids (TSS), total phenols and tannins (TP, TT). It was observed that the water solutes extraction power is significantly reduced for higher quantities of cork processed. Valid relationships between parameters were established not only envisaging wastewater characterization but also to provide an important tool for wastewater monitoring and for process control/optimization. Boiling water biodegradability presented decreasing values with the increase of cork processed and for the final wastewater its value is always lower than 0.5, indicating that these wastewaters are very difficult to treat by biological processes. The biodegradability was associated with the increase of tannin content that can rise up to 0.7 g/L. These compounds can be used by other industries when concentrated and the clarified wastewater can be reused, which is a potential asset in this wastewater treatment.
- Cork industry wastewater partition by ultra/nanofiltration: A biodegradation and valorisation studyPublication . Bernardo, Marisa; Santos, Ana; Cantinho, Paula; Minhalma, MiguelWastewater from cork processing industry present high levels of organic and phenolic compounds, such as tannins, with a low biodegradability and a significant toxicity. These compounds are not readily removed by conventional municipal wastewater treatment, which is largely based on primary sedimentation followed by biological treatment. The purpose of this work is to study the biodegradability of different cork wastewater fractions, obtained through membrane separation, in order to assess its potential for biological treatment and having in view its valorisation through tannins recovery, which could be applied in other industries. Various ultrafiltration and nanofiltration membranes where used, with molecular weight cut-offs (MWCO) ranging from 0.125 to 91 kDa. The wastewater and the different permeated fractions were analyzed in terms of Total Organic Carbon (TOC), Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD), Total Phenols (TP), Tannins, Color, pH and Conductivity. Results for the wastewater shown that it is characterized by a high organic content (670.5-1056.8 mg TOC/L, 2285-2604 mg COD/L, 1000-1225 mg BOD/L), a relatively low biodegradability (0.35-0.38 for BODs/COD and 0.44-0.47 for BOD20/COD) and a high content of phenols (360-410 mg tannic acid/L) and tannins (250-270 mg tannic acid/L). The results for the wastewater fractions shown a general decrease on the pollutant content of permeates, and an increase of its biodegradability, with the decrease of the membrane MWCO applied. Particularly, the permeated fraction from the membrane MWCO of 3.8 kDa, presented a favourable index of biodegradability (0.8) and a minimized phenols toxicity that enables it to undergo a biological treatment and so, to be treated in a municipal wastewater treatment plant. Also, within the perspective of valorisation, the rejected fraction obtained through this membrane MWCO may have a significant potential for tannins recovery. Permeated fractions from membranes with MWCO lower than 3.8 kDa, presented a particularly significant decline of organic matter and phenols, enabling this permeates to be reused in the cork processing and so, representing an interesting perspective of zero discharge for the cork industry, with evident environmental and economic advantages. (C) 2010 Elsevier Ltd. All rights reserved.
- Eficácia da música no controlo da ansiedade durante o exame de PET/TCPublication . Santos, Ana; Martins, Ana; Sousa, Carolina; Vieira, Lina; Grilo, Ana Monteiro; Carolino, Elisabete; Castro, Maria; Alonso, JuanIntrodução – Em exames de tomografia de emissão de positrões (PET, do acrónimo inglês Positron Emission Tomography) com tomografia computadorizada (TC) a ansiedade pode interferir com a experiência do paciente e até com o diagnóstico. A música tem vindo a ser utilizada para controlo da ansiedade dos pacientes em inúmeros contextos clínicos. Objetivo – Verificar o efeito da música no controlo da ansiedade dos pacientes durante exames PET/TC. Métodos – Estudo exploratório onde foram incluídos 22 pacientes no grupo de controlo (GC) e 23 no grupo experimental (GE) que realizaram exame de PET/TC com fluorodesoxiglucose marcada com flúor-18 (18F-FDG). Os pacientes do GE ouviram música durante a aquisição de imagens, enquanto os do GC não. Todos os pacientes responderam a questionários sobre a experiência do exame (QEE) e a uma versão reduzida do questionário State-Trait Anxiety Inventory-State (STAI-S) antes do exame (AE) e depois do exame (DE). Procedeu-se ainda à medição da pressão arterial sistólica (PAS) e diastólica (PAD) AE e DE. Resultados – Os valores do STAI-S não diferiram significativamente entre grupos, quer AE quer DE. Contudo, do AE para o DE verificou-se um aumento destes valores no GC e, em oposição, uma diminuição no GE. Comparando as PA entre o GE e o GC constatou-se que não existem diferenças significativas AE, mas existem DE, sendo que no GE os valores são inferiores aos do GC. No GE 91,3% dos pacientes relatou que a música é um auxílio durante o exame, classificando em média o nível de utilidade em 4,4 (0 a 5, sendo 5 o máximo). Conclusões – No presente estudo ouvir música parece ser eficaz no controlo da ansiedade em exames de PET/TC, mostrando-se os pacientes satisfeitos quanto à utilização desta técnica.
- Futuros sobre produtos energéticos: caso especial do petróleo brutoPublication . Santos, Ana; Ferreira, Domingos da SilvaNo âmbito da conclusão da segunda fase do Mestrado em Contabilidade do ISCAL (Instituto Superior de Contabilidade e Administração de Lisboa) foi elaborado um trabalho de dissertação no âmbito das matérias dadas nas unidades curriculares constituintes deste mestrado. O tema escolhido para objecto do meu estudo foi os Futuros sobre Produtos Energéticos. Na realização do meu trabalho, será apresentado numa primeira fase a elaboração de um estudo teórico sobre os derivados em geral e os futuros em particular. Numa segunda fase serão apresentados os resultados e conclusões da análise às cotações diárias ao longo de seis meses do preço à vista do brent crude oil e dos cinco primeiros contratos de futuros sobre aquele activo subjacente. De forma a entender melhor o tema, está a ser realizada uma recolha e análise de dados gerais relacionados com o tema através de pesquisas bibliográficas e na internet.