Cork industry wastewater partition by ultra/nanofiltration: A biodegradation and valorisation study

Wastewater 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

Quem investirá na infraestrutura num contexto de tarifação fixa? Um contributo de análise ao sector das telecomunicações

Mestrado em EconomiaA generalização do acesso à Internet impactou decisivamente o sector das telecomunicações. O novo modelo de negócio dos operadores, assente numa flat rate implicou uma quebra das receitas operacionais, tendo como consequência o aumento dos níveis de risco e incerteza no sector. A problemática prende-se com o nível insuficiente de investimento na infraestrutura, tendo em conta o aumento exponencial do tráfego de dados. Tendo como instrumento de análise um exercício teórico, conclui-se que a hipótese de se alcançar uma situação de congestionamento da rede é suficientemente verosímil. Nesta grelha de análise sugere-se a intervenção do regulador, com o propósito de estabelecer uma parceria estratégica entre os vários intervenientes-chave, de forma a tornar sustentável o aumento esperado do tráfego.The widespread use of Internet access has had a decisive impact on the telecommunications sector. The new business model of operators based on a flat rate implied a fall in operating revenues, with the consequence of increasing levels of risk and uncertainty in the sector. The problem is the insufficient level of investment in infrastructure, given the exponential increase in data traffic. Having as theoretical analysis a theoretical exercise, it is concluded that the hypothesis of reaching a network congestion situation is plausible enough. This analysis grid suggests the intervention of the regulator, with the purpose of establishing a strategic partnership between the various key stakeholders, in order to make the expected increase in traffic sustainable.info:eu-repo/semantics/publishedVersio

Cork industry wastewater characterization assessment of the biodegradability, reuse and of the relationship between BOD, COD and tannins with TOC

Cork 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

Concentration polarization quantification and minimization in cork process wastewater ultrafiltration by an ozone pretreatment

Concentration polarization and membrane fouling have been identified as the main problems during the ultrafiltration treatment of cork processing wastewaters. These problems drastically reduce the permeate fluxes and, therefore, their potential applications. In this work, a soft ozonation pretreatment was applied to minimize these undesirable effects. A new systematic study was carried out for membranes with different molecular weight cut-offs and at different operating conditions to monitor and quantify the concentration polarization caused by the wastewater's remaining ozonated compounds. Film theory was used to correlate the mass transfer coefficient, k, and the intrinsic rejection coefficient, f ', with the resistance introduced by concentration polarization. The ultrafiltration treatment was carried out under varying hydrodynamic operating conditions (circulating flow rates of 100-200 L/h) and transmembrane pressures (1-3 bar) for a set of four cellulose acetate membranes covering a wide range of molecular weight cut-offs (5000-100,000 Da) and hydraulic permeabilities (25-110 kg/h/m(2)/bar). The ozone pretreatment (at wastewater pH) reduced the phenolic content selectively (direct oxidation) by more than 50%, reducing membrane fouling and concentration polarization and increasing permeate fluxes (by 22-45%) and mass transfer coefficients (up to six times).info:eu-repo/semantics/publishedVersio

Cork processing wastewater treatment/valorisation by nanofiltration

Nanofiltration process for the treatment/valorisation of cork processing wastewaters was studied. A DS-5 DK 20/40 (GE Water Technologies) nanofiltration membrane/module was used, having 2.09 m(2) of surface area. Hydraulic permeability was determined with pure water and the result was 5.2 L.h(-1).m(-2).bar(-1). The membrane presents a rejection of 51% and 99% for NaCl and MgSO4 salts, respectively. Two different types of regimes were used in the wastewaters filtration process, total recycling mode and concentration mode. The first filtration regime showed that the most favourable working transmembrane pressure was 7 bar working at 25 degrees C. For the concentration mode experiments it was observed a 30% decline of the permeate fluxes when a volumetric concentration factor of 5 was reached. The permeate COD, BOD5, colour and TOC rejection values remained well above the 90% value, which allows, therefore, the concentration of organic matter (namely the tannin fraction) in the concentrate stream that can be further used by other industries. The permeate characterization showed that it cannot be directly discharged to the environment as it does not fulfil the values of the Portuguese discharge legislation. However, the permeate stream can be recycled to the process (boiling tanks) as it presents no colour and low TOC (< 60 ppm) or if wastewater discharge is envisaged we have observed that the permeate biodegradability is higher than 0.5, which renders conventional wastewater treatments feasible

Efeitos fisiológicos da hipóxia normobárica

Os estudos apresentados nesta dissertação pretendem descrever o efeito da exposição aguda à hipóxia normobárica (HN) na resposta fisiológica ao exercício. Numa primeira fase realizaram-se dois estudos metodológicos, um para determinar a diferença entre a utilização de uma ou de duas transições do repouso para o exercício no domínio pesado, na modelação da cinética do consumo de oxigénio (VO2cin) (estudo I) e outro para determinar a reprodutibilidade dos parâmetros da VO2cin para um intervalo de 48 horas e verificar se uma pausa de 105 minutos permite uma recuperação total do exercício prévio realizado no domínio de intensidade pesado (estudo II). Na segunda fase foram realizados três estudos. No estudo III foram analisados os efeitos fisiológicos de uma exposição passiva intermitente à HN (IHE) no exercício subsequente, no domínio de intensidade pesado. No estudo IV, caracterizou-se a influência da altitude simulada na resposta fisiológica aguda no exercício de carga constante, no domínio de intensidade moderado. No estudo V, descrevemos os efeitos agudos da altitude simulada na variabilidade da frequência cardíaca (HRV) em exercício de carga constante no domínio de intensidade moderado. Concluiu-se o seguinte: 1. Utilizar uma ou duas transições do repouso para o exercício no domínio pesado não levou a resultados diferentes na qualidade da modelação da VO2cin; 2. Uma pausa de 48 horas entre avaliações não assegura a reprodutibilidade dos parâmetros da VO2cin; 3. Quando as transições são executadas com pelo menos 105 min de intervalo, não é visível qualquer efeito do exercício prévio; 4. A exposição passiva à hipóxia intermitente, anula o efeito de recuperação total ao exercício prévio, mesmo que a pausa tenha uma duração de 105 minutos; 5.A exposição à HN durante o exercício de carga constante no domínio de intensidade moderado, altera a resposta metabólica, surgindo características de exercício pesado em relação à ventilação, frequência cardíaca, produção de dióxido carbono e concentração de lactato; 6. A HIE ao nível do mar é preditor do comportamento da SaO2 no teste de carga constante em altitude simulada; 7. A diminuição da FiO2 durante o exercício de carga constante causa a diminuição da variabilidade da frequência cardíaca, associada ao aumento da atividade simpática e inibição da atividade vagal. A conclusão final é a de que os efeitos agudos da exposição à hipoxia constituem um stress adicional que modifica a resposta fisiológica, com implicações para o planeamento do treino, nomeadamente, com necessidade de ajustar os tempos de recuperação após exposição passiva e o doseamento das cargas de treino em hipóxia.The five studies presented in this thesis aimed to describe the physiological responses to acute normobaric hypoxia (HN). Previously, two methodological studies were performed, study one intended to evaluate if modeling oxygen uptake kinetics (VO2cin) with only a transition from rest to exercise in heavy intensity domain is a procedure as valid as with two transitions; study two aimed to verify if an interval of 48 hours between evaluations allowed VO2cin parameters to be reproducible and to determine if a rest period of 105 minutes would allow a full recovery from a previous bout of heavy domain exercise. The third study aimed to determine the physiological effects of intermittent passive exposure to hypoxia (IHE) in subsequent normoxic exercise in heavy intensity domain. The fourth study intended to describe the effects of incremental simulated altitude (ISA) in the physiological responses of constant load exercise in moderate intensity domain and the fifth study aimed to analyze the heart rate variability (HRV) in the same experimental protocol of previous study. We concluded that 1. modelling VO2cin with one transition from rest to heavy intensity domain exercise does not differ from a procedure with two transitions; 2. A 48 hours interval between evaluation sessions showed low reproducibility; 3. A pause of 105 min between measurements is sufficient to prevent any prime effect. 4. One hour of IHE between bouts of exercise eliminates the full recovery effect observed after a pause of 105 minutes; 5. ISA during constant load exercise in moderate intensity domain imposes a change in the metabolic response to exercise with the same characteristics as heavy domain exercise; 6. Hypoxemia induced by exercise at sea level is a predictor of arterial oxygen saturation behavior during an ISA test; 7. ISA during moderate intensity exercise decreases HRV because of increased sympathetic nervous system activity and a withdrawal of vagal activity Overall conclusion is that acute exposure to simulated altitude promotes an additional stress and amplifies physiological responses to exercise. Recovery time between exercises and intensity adjustment of exercise in simulated altitude must be carefully planned

Nanofiltration of surface water for the removal of endocrine disruptors

The assessment of surface water nanofiltration (NF) for the removal of endocrine disruptors (EDs) Nonylphenol Ethoxylate (IGEPAL), 4-Nonylphenol (NP) and 4-Octylphenol (OP) was carried out with three commercial NF membranes - NF90, NF200, NF270. The permeation experiments were conducted in laboratory flat-cell units of 13.2 x 10(-4) m(2) of surface area and in a DSS Lab-unit M20 with a membrane surface area of 0.036 m2. The membranes hydraulic permeabilities ranged from 3.7 to 15.6 kg/h/m(2)/bar and the rejection coefficients to NaCl, Na2SO4 and Glucose are for NF90: 97%, 99% and 97%, respectively; for NF200: 66%, 98% and 90%, respectively and for NF270: 48%, 94% and 84%, respectively. Three sets of nanofiltration experiments were carried out: i) NF of aqueous model solutions of NP, IGEPAL and OP running in total recirculation mode; ii) NF of surface water from Rio Sado (Settibal, Portugal) running in concentration mode; iii) NF of surface water from Rio Sado inoculated with NP, IGEPAL and OP running in concentration mode. The results of model solutions experiments showed that the EDs rejection coefficients are approximately 100% for all the membranes. The results obtained for the surface water showed that the rejection coefficients to natural organic Matter (NOM) are 94%, 82% and 78% for NF90, NF200 and NF 270 membranes respectively, with and without inoculation of EDs. The rejection coefficients to EDs in surface water with and without inoculation of EDs are 100%, showing that there is a fraction of NOM of high molecular weight that retains the EDs in the concentrate and that there is a fraction of NOM of low molecular weight that permeates through the NF membranes free of EDs

Assessment of saccharide fractionation by ultrafiltration and nanofiltration

This paper addresses the investigation of the fractionation of saccharide mixtures and saccharide mixtures with calcium using ultrafiltration (UF) and nanofiltration (NF). A set of cellulose acetate membranes covered a wide range of molecular weight cut-off (MWCO) ranging from 250 to 46,000 Da and the total feed concentration of saccharides mixtures varied from 1550 to 4700 ppm with the ratio of the two saccharides-solutes (glucose to raffinose) being kept constant at the value of 1.8. The evolution pattern of the saccharide concentration ratio in the UF/NF permeate streams displayed a dependence on the membrane MWCO, on the total sugar concentration and on the presence of calcium ions. For the highest total sugar content, the membranes with MWCO from 2000 to 7000 Da showed saccharide fractionation capability that was enhanced in the presence of calcium. The Steric Pore Flow Model was used to predict individual solute permeation behaviours and to assess the deviations to steric hindered transport of the solutes in multi-component saccharide solutions. (C) 2008 Elsevier B.V. All rights reserved

A responsabilidade dos administradores para com a sociedade: o princípio da "business judgment rule" e a sua transposição para o ordenamento jurídico português

A responsabilidade civil dos administradores para com a sociedade constitui um tema de grande importância, dada a crescente globalização do mercado internacional e a consequente necessidade de promover a liberdade de escolha, a criatividade, a inovação e o empreendedorismo dos administradores na tomada de decisões empresariais que visam a obtenção de lucro. A discricionariedade empresarial deve ser limitada por critérios gerais de conduta exigíveis aos administradores, com o intuito de evitar os atos negligentes de má gestão societária, e encontram-se consagrados no atual artigo 64.º do Código das Sociedades Comerciais. Os princípios da "corporate governance" de origem norte-americana, influenciaram a consagração dos deveres gerais dos administradores na lei societária portuguesa, correspondendo ao regime substantivo utilizado para aferir a responsabilidade civil dos administradores para com a sociedade. A regra da business judgment rule oriunda da jurisprudência norte-americana, que visa excluir a valoração do mérito das decisões empresariais dos administradores, independentemente do seu resultado, foi transposta para o ordenamento jurídico português no n.º 2, do artigo 72.º do Código das Sociedades Comerciais. A forma dessa transposição e o sentido da "business judgment rule" dado pela introdução do novo preceito, tem sido alvo de grande controvérsia na doutrina portuguesa, dado que parece elencar uma causa de exclusão da responsabilidade dos administradores. Para afastar a responsabilidade civil dos administradores, é necessário conjugar o n.º 2, do artigo 72.º do Código das Sociedades Comerciais, com o regime substantivo dos deveres gerais dos administradores previsto no artigo 64.º do Código das Sociedades Comerciais.The civil liability of the directors to the society is a very important theme, given the increasing of international market globalization and the consequent need to promote the freedom of choice, the creativity, the innovation and the entrepreneurship of directors in the corporate decision taking to obtain profit. The corporate discretion must be limited by general criteria of conduct due the directors, to avoid the negligent acts of corporate mismanagement, that are established on the actual article 64.º of the Commercial Company Code. The Principles of Corporate Governance originally from North America, influenced the establishment of the director´s general duties in the portuguese corporate law, that corresponds to the substantive regime used to assess the civil liability of the directors to the society. The business judgment rule originally from the North America case law, that intends to exclude the evaluation of the merit of the director’s corporate decisions, in spite of its results, was transposed to the portuguese law system to the n. º 2, of article 72.º of the Commercial Company Code. The transposition form and the meaning of the business judgment rule introduced by the new rule, has been a matter of controversy in the portuguese doctrine, because it seems to establish a cause of exclusion of director’s civil liability. To remove the director’s civil liability, it´s necessary to combine the n. º 2, of article 72.º of Commercial Company Code, with the substantive regime of directors general duties established in the article 64.º of Commercial Company Code

Análise modal de um edifício de paredes de alvenaria resistente

O parque habitacional em Portugal é composto por um elevado número de edifícios antigos constituídos por paredes de alvenaria resistente. Nos últimos anos tem-se constatado um interesse crescente na preservação e reutilização dessas construções, por se encontrarem frequentemente em zonas históricas privilegiadas, e com potencial interesse de exploração económica. Estes motivos têm levado à realização de intervenções estruturais nesses edifícios, com vista à reorganização dos espaços, podendo desencadear alterações no seu comportamento estrutural. O objetivo primordial deste estudo é avaliar as alterações da resposta modal de um edifício de paredes de alvenaria resistente, sujeito a uma intervenção de remoção das paredes num dos seus fogos. Para tal, realizaram-se duas campanhas experimentais de identificação modal à vibração ambiente, com o intuito de determinar as propriedades dinâmicas da estrutura, antes e após a intervenção. Procedeu-se à elaboração de um modelo de elementos finitos da estrutura recorrendo ao programa de análise de estruturas SAP2000, que permitiu efetuar também a correspondente análise numérica do problema. Foi ainda realizada uma análise ao comportamento modal do edifício, onde se identificaram diversas hipóteses que influenciam a resposta dinâmica da estrutura, tendo sido desenvolvidos alguns modelos numéricos, com o objetivo de examinar nomeadamente a influência dos edifícios adjacentes, e da interação solo-estrutura, no comportamento global do edifício analisado