Tratamento de efluentes da indústria de conservas de peixe por coagulação-floculação com diferentes coagulantes

Os principais problemas ambientais das indústrias de conservas de peixe são o elevado consumo de água e o elevado conteúdo de matéria orgânica, óleos e gorduras e sais nos seus efluentes. Cada vez mais há uma necessidade de se considerar o tratamento deste tipo de efluentes de forma a que estes cumpram os requisitos de qualidade ditados pela legislação. Assim, este trabalho tem como objectivo o estudo do tratamento primário de efluentes da indústria de conservas de peixe através de um tratamento por coagulação-floculação química. Para tal, testaram-se quatro coagulantes diferentes (um orgânico e três inorgânicos) e várias concentrações de cada um deles (100, 200 e 400 mg/L), de forma a seleccionar as melhores condições do processo. Contudo, observou-se que não existe um único coagulante óptimo, tudo depende do objectivo pretendido. Entre as condições estudadas pode-se afirmar que, se o objectivo for a maximização da remoção de óleos e gorduras, a melhor opção será a utilização de 200 mg/L de cloreto de polialumínio, atingindo remoções de 99,5%. Se o pretendido for a remoção de sólidos suspensos totais, é recomendada a utilização de 400 mg/L de cloreto de ferro, obtendo remoções de 85,8%.Este trabalho é parcialmente financiado pela FCT –Fundação para a Ciência e a Tecnologia e pelo FEDER sob o programa COMPETE (Projecto PEst-C/EQB/LA0020/2013) e pelo projecto ValorPeixe –Valorização de subprodutos e águas residuais da indústrias de conservas de peixe, projecto em co-promoção I&DT QREN, nº 13634, financiado pelo FEDER através do POFC – Programa Operacional Factores de Competitividade, pelos quais os autores estão agradecidos. Os autores querem também agradecer à indústria de conservas de peixe em estudo pelas amostras de efluente e à Rivaz Química (Maia, Portugal) por cederem gentilmente o coagulante orgânico RIPOL 070. A autora Raquel O. Cristóvão quer também agradecer à FCT pela sua bolsa de pós-doutoramento (SFRH/BPD/81564/2011).info:eu-repo/semantics/publishedVersio

Tratamento de efluentes da indústria de conservas de peixe com vista à sua reutilização

É de grande interesse ambiental e económico estudar o tratamento de efluentes da indústria de conservas de peixe de forma a obter uma água com os requisitos de qualidade necessários para considerar a sua reutilização e/ou reciclagem para a unidade industrial. No entanto, o elevado conteúdo de sal tem sido um fator limitante, pois persiste mesmo após o tratamento convencional dos efluentes. Assim, foi estudado e otimizado um processo de clarificação por filtração rápida, osmose inversa e desinfeção UV, como tratamento de afinação do efluente previamente tratado, de modo a remover sólidos, sais e microrganismos remanescentes. Este tratamento de afinação permitiu alcançar eficiências de remoção de 78% de sólidos suspensos totais, 97,3% de carbono orgânico dissolvido, 99,8% de azoto total solúvel, 99,1% de condutividade, acima de 96% de aniões e catiões e 100% de bactérias heterotróficas (UFC), atingindo-se, como pretendido, água com os requisitos de qualidade necessários para ser reutilizada ou reciclada para a unidade industrial. Consequentemente, é possível uma redução da descarga de efluentes, uma limitação do uso de água e uma redução dos custos associados.Este trabalho é parcialmente suportado pelo projeto PEst C/EQB/LA0020/2013, financiado pela FEDER através do Programa Operacional Fatores de Competitividade –COMPETE e pela Fundação para a Ciência e a Tecnologia –FCT e pelo projeto em co-promoção I&DT QREN nº 13634, ValorPeixe – Valorização de Subprodutos e Águas Residuais da Indústria de Conservas de Peixe, financiado pela FEDER através do Programa Operacional Fatores de Competitividade POFC aos quais os autores se encontram agradecidos. Os autores querem também agradecer à indústria de conservas em estudo pelas amostras de efluente. A autora Raquel O. Cristóvão agradece também à FCT pela bolsa de Pós-doutoramento (SFRH/BPD/81564/2011).info:eu-repo/semantics/publishedVersio

Fish canning industry wastewater treatment for water reuse – a case study

The valorization of wastewaters from the fish canning industry is of great concern, not only because of the high quantities generated, but also economic and environmental benefits may result from a proper treatment approach of the waste generated while reducing costs related to wastewater discharge. A limiting factor for reuse and recycling treated fish canning wastewater into an industrial plant and also for other uses is the high salt content, which persists even after conventional treatment. So, the reuse of fish canning industrial wastewater was assessed by combining conventional treatments, such as sedimentation, chemical coagulation-flocculation and aerobic biological degradation (activated sludge process) followed by a polishing step by reverse osmosis (RO) and ultraviolet (UV) disinfection. In this investigation all these processes were optimized in order to remove essentially the effluent suspended particles (primary treatment), the organic matter content in the biological aerated reactor (secondary treatment) and, finally, the remaining salts and microorganisms (tertiary treatment). The overall removal efficiencies obtained were: 99.9% for dissolved organic carbon (DOC), 99.8% for oil and grease (O&G), 98.4% for total suspended solids (TSS), above 96% for anions and cations and 100% for heterotrophic bacteria expressed as colony-forming units (CFU). The final clarified effluent was found to have the quality requirements to be recycled or reused in the industrial plant, allowing the reduction of the effluent to be discharged, the water use and the costs of tap water for industrial use. As regards the energy and chemicals costs, to obtain a treated effluent to be reused in the process costs 0.85 V/m3. This value can be reduced by about 60% if the goal is only to meet the legislated standards for the effluent discharge into water bodies. Tap water for the industrial plant costs about 2.1 V/m3.This work is partially supported by project PEst-C/EQB/LA0020/2013,financed by FEDER through COMPETE - Programa Operacional Factores de Competitividade and by FCT - Fundação para a Ciência e a Tecnologia and by ValorPeixe - Valorizaçãode Sub-produtos e Águas Residuais da Indústria de Conservas de Peixe, project in co-promotion I&DT QREN, nº13634,financed by FEDER through POFC - Programa Operacional Factores de Competitividade for which the authors are thankful. Raquel O. Cristóvão thanks FCT for the Post-doc Scholarship (SFRH/BPD/81564/2011).info:eu-repo/semantics/publishedVersio

Primary treatment optimization of a fish canning wastewater from a Portuguese plant

A sequence with three stages was optimized as a primary treatment for wastewaters from a fish canning industry of northern Portugal. Sedimentation tests were assessed at different times. The removal of a high fraction (75%) of oil and grease (O&G) and of some (48%) total suspended solids (TSS) occurred after a settling time of 1.5h. Coagulant dosage and pH value were optimized in the coagulation/flocculation treatment using several organic and inorganic coagulants. Best removal efficiencies (99.2% O&G, 85.8% TSS and 25.2% dissolved organic carbon (DOC)) were reached using 400mg/L of FeCl3 at raw pH wastewater. DAF was also tested, optimizing chamber pressure and recycle ratio. Removals of 94% for O&G and 43% for TSS were achieved. The coupling of the latter two processes was also investigated, but no improvement of the previous results was observed. The best approach proved to be a decantation process followed by coagulation/flocculation treatment. © 2014 The Authors

Nugget Formation and Mechanical Behaviour of Friction Stir Welds of Three Dissimilar Aluminum Alloys

The aim of this research was to investigate the influence of the properties of the base materials and welding speed on the morphology and mechanical behavior of the friction stir welds of three dissimilar aluminum alloys in a T-joint configuration. The base materials were the AA2017-T4, AA5083-H111, and AA6082-T6 alloys in 3 mm-thick sheets. The AA6082-T6 alloy was the stringer, and the other alloys were located either on the advancing or retreating sides of the skin. All the T-joint welds were produced with a constant tool rotation speed but with different welding speeds. The microstructures of the welds were analyzed using optical microscopy, scanning electron microscopy with energy dispersive spectroscopy, and the electron backscatter diffraction technique. The mechanical properties were assessed according to micro-hardness, tensile, and fatigue testing. Good quality welds of the three dissimilar aluminum alloys could be achieved with friction stir welding, but a high ratio between the tool's rotational and traverse speeds was required. The welding speed influenced the weld morphology and fatigue strength. The positioning of the skin materials influenced the nugget morphology and the mechanical behavior of the joints. The joints in which the AA2017 alloy was positioned on the advancing side presented the best tensile properties and fatigue strength.info:eu-repo/semantics/publishedVersio

Fish canning wastewater treatment by activated sludge: Application of factorial design optimization. Biological treatment by activated sludge of fish canning wastewater.

The optimization of hydraulic retention time (HRT) and initial organic matter concentration for dissolved organic carbon (DOC) abatement of wastewater from a fish canning industry of northern Portugal by activated sludge was investigated using response surface methodology (RSM). The two parameters were chosen since it was found that the treatment efficiency is mainly influenced by them. The experimental data on DOC r emoval were fitted into a quadratic polynomial model using factorial design and RSM. The optimum process conditions were determined by analyzing the response surface of a three-dimensional plot and by solving the regression model equation. The obtained results showed a HRT of 6.4. h and an initial DOC of 406.2. mg/L as the best treatment conditions. Under these conditions, the maximum predicted DOC removal was 88.0%, confirming the feasibility and the reliability of fish canning wastewater treatment by activated sludge for organic content removal.This work is partially supported by project PEst-C/EQB/LA0020/2011, financed byFEDER through COMPETE – Programa Operacional Factores de Competitividade and by FCT – Fundação para a Ciência e a Tecnologia and by project Valor Peixe – Valorização de Subprodutos e Águas Residuais da Indústria de Conservas de Peixe, projectinco-promotion I&DTQREN, No.13634, financed by FEDER through POFC – Programa Operacional Factores de Competitividade for which the authors are thankful.The authors also wish to thank the cannery in study for wastewater samples.Authors also thank FCT for the Post- doc Scholarship (SFRH/BPD/81564/2011).info:eu-repo/semantics/publishedVersio

Exploring the potential of vegetation corridors in forest fire hazard reduction at the landscape level: examples from Portugal

In north-eastern Portugal, holm oak (Quercus rotundifolia) woodlands have persisted in the landscape despite the occurrence of frequent fires. The hypothesis that these elements have a role in fire related processes has been proposed by foresters and scientists but only recently it has been addressed. In this research we analysed the current distribution of holm oak remnants in the region in terms of features such as slope, aspect, distance to streams, and position in the slope. We also compared their distribution in relation to the distribution of areas burned in the last decades. We found that holm oak woodlands are often adjacent to burned areas suggesting a barrier effect of these vegetation structures. Also, the woodlands are often located towards the bottom of very steep slopes. Additionally, we tested the hypothesis that these patches arrest wildfires based on a modeling and simulation approach using field data collected in edges of holm oak woodlands. Computer simulated fire behaviour provided evidence that variations in intensity and velocity across holm oak edges make it possible for these woodlands to affect significantly fire spread. Founded on these results we explored the potential for holm oak corridors to be used in fire hazard reduction planning

Bond energy/eond order relationships for N-O linkages and a quantitative measure of ionicity: the rôle of nitro groups in hydrogen bonding

The nitro group is active in metabolic systems and can be found as an integral part of a number of useful curative drugs and many toxic substances. The basis for much of this activity is not fully understood. It is not necessarily caused directly by through-bond electronic effects but may also be due to direct H-bonding to nitro or to indirect interference by the nitro group with existing H-bonding. An unusual effect of a nitro substituent on kinetic results from urethane addition/elimination reactions (Scheme 1) has been ascribed to some form of self-association, which was neither specified nor quantified. To investigate self-association phenomena caused by a nitro group, a bond energy/bond order formula for N–O bonds has been developed and then used to interpret relative amounts of covalent and ionic contributions to total N–O bond energy. Calculated bond energies were then used to obtain enthalpies of formation for H-bonds to nitro groups in crystals and in solution. Similar results from solution data reveal that direct H-bonding to nitro is much weaker than in crystals, unless intramolecular H-bonding can occur. The results revealed that the 'self-association' effects observed for nitro substituents in urethanes (Scheme 1) were not caused by nitro participating directly in intermolecular bonding to NH of another urethane but by an indirect intramolecular action of the nitro group on pre-existing normal NH–O amide/amide type H-bonding

3-( E )-But-2-enoxy-1,2-benzisothiazole 1,1-dioxide: unusual C—O—C ether bond lengths and reactivity

Ethers such as the title compound, C~HIINO3S, (1), rearrange thermally to give N-allyl isomers, (2), in high yield. The X-ray structure determination of the title ether shows a central C--O--C linkage which has one very short (notional) C--O single bond and one exceptionally long single C--O bond. The thermal migration of allyl from the O to the N atom involves the breaking of one of the ether bonds in (1) and a shortening of the other as it becomes a formal carbonyl group in the product (2). The rearrangement is thus considerably assisted by the ground-state structure of the starting ether, in which the bond to be broken is already stretched and the one that is to form a carbonyl group is already a substantial partial double bond

Evaluation of the joint effect of glyphosate and dimethoate using a small-scale terrestrial ecosystem

In the present work a small-scale terrestrial ecosystem (STEM) containing a soil collected from an agricultural field in Central Portugal was used to evaluate the effects of the combination of the herbicide glyphosate and the insecticide dimethoate. Earthworms (Eisenia andrei), isopods (Porcellionides pruinosus), turnip seeds (Brassica rapa), and bait-lamina strips were placed in the STEM. The results showed that the application of the recommended field dose of both pesticides did not cause any effect on the weight variation of earthworms and growth of the plants. The application of the herbicide, even at 5 and 10 times the field dose, increased feeding activity in soil (bait-lamina test), although the application of dimethoate led to a decrease in feeding activity in all concentrations tested. The binary mixtures performed showed that according to the Independent Action model, synergism (higher effect than expected from the single exposures) was observed in both the shoot length and fresh weight of B. rapa at 5 times the field dose, but antagonism was observed at 10 times the field dose. Regarding the germination success, synergism was observed at the field dose, but antagonism was detected at 5 times and 10 times the field dose. There was a decrease on the earthworm's weight in all concentrations tested, although no statistical differences were observed in any of the treatments made. Regarding depth distribution of E. andrei, worms were found in the upper layer more than it was predicted for all concentrations. In the mixtures with the field and 5 times the field dose there was a decrease in the feeding activity (bait-lamina consumption) by the soil fauna. From the four biomarkers assessed on the isopods (Catalase, Acetylcholinesterase, Glutathione-S-transferase, and Lipid peroxidation), only a significant decrease in the Acetylcholinesterase activity upon dimethoate and the binary mixtures exposures performed with the field dose was observed and on Lipid peroxidation at the field doses of single and binary exposures. (C) 2011 Elsevier Inc. All rights reserved