1,070 research outputs found

    Effect of ultrasound, low-temperature thermal and alkali pre-treatments on waste activated sludge rheology, hygienization and methane potential

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    Waste activated sludge is slower to biodegrade under anaerobic conditions than is primary sludge due to the glycan strands present in microbial cell walls. The use of pre-treatments may help to disrupt cell membranes and improve waste activated sludge biodegradability. In the present study, the effect of ultrasound, low-temperature thermal and alkali pre-treatments on the rheology, hygienization and biodegradability of waste activated sludge was evaluated. The optimum condition of each pre-treatment was selected based on rheological criteria (reduction of steady state viscosity) and hygienization levels (reduction of Escherichia coli, somatic coliphages and spores of sulfite-reducing clostridia). The three pre-treatments were able to reduce the viscosity of the sludge, and this reduction was greater with increasing treatment intensity. However, only the alkali and thermal conditioning allowed the hygienization of the sludge, whereas the ultrasonication did not exhibit any notorious effect on microbial indicators populations. The selected optimum conditions were as follows: 27,000 kJ/kg TS for the ultrasound, 80 °C during 15 min for the thermal and 157 g NaOH/kg TS for the alkali. Afterward, the specific methane production was evaluated through biomethane potential tests at the specified optimum conditions. The alkali pre-treatment exhibited the greatest methane production increase (34%) followed by the ultrasonication (13%), whereas the thermal pre-treatment presented a methane potential similar to the untreated sludge. Finally, an assessment of the different treatment scenarios was conducted considering the results together with an energy balance, which revealed that the ultrasound and alkali treatments entailed higher costs

    Biocompatibility Assessment of Poly(lactic acid) Films after Sterilization with Ethylene Oxide in Histological Study In Vivo with Wistar Rats and Cellular Adhesion of Fibroblasts In Vitro

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    Biomaterials must meet certain fundamental requirements for their usage in living beings, such as biocompatibility, bifunctionality, and sterilizability, without having chemical and structural changes. The biocompatibility of poly(lactic acid) (PLA) films, shaped by compression, was evaluated after sterilization by ethylene oxide by a histological in vivo test with Wistar rats and cytotoxicity in cell adhesion in vitro. The cytotoxicity test was performed by the reduction of tetrazolium salt (MTT). Thermal and chemical changes in PLA films concerning the proposed sterilization process and characteristics were not observed to evidence polymer degradation due to sterilization. The analysis of the cytotoxicity by the MTT method has shown that the sterilized PLA films are not cytotoxic. The adhesion and proliferation of fibroblasts on PLA films were homogeneously distributed over the evaluation period, showing an elongated appearance with unnumbered cytoplasmic extensions and cell-cell interactions. By examining the biocompatibility in a histological study, a mild tissue inflammation was observed with the presence of fibrosis in the samples that had been exposed for 21 days in the rats’ bodies. PLA films sterilized with ethylene oxide did not exhibit cell adhesion in vitro and toxicity to the surrounding tissue in vivo and they may be used in future in vivo testing, according to histological findings in Wistar rats in the present study

    Hygienization and control of Diplodia seriata fungus in vine pruning waste composting and its seasonal variability in open and closed systems

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    After the ban on sodium arsenite, waste management alternatives to the prevalent burning method, such as the hygienization and biodegradation in solid phase by composting, are required for the pruned material from grapevines affected by various fungi. In this work the dynamics of a fungus associated with vine decay (Diplodia seriata) during the composting process of a mixture of laying hen manure and vine pruning waste (2:1 w/w) have been investigated in an open pile and a discontinuous closed biodigester. Through the optimization of the various physical–chemical parameters, hygienization of the infected waste materials was attained, yielding class-A organo-mineral fertilizers. Nevertheless, important differences in the efficiency of each system were observed: whereas in the open pile it took 10 days to control D. seriata and 35 additional composting days to achieve full inactivation, in the discontinuous biodigester the fungus was entirely inactivated within the first 3–7 days. Finally, the impact of seasonal variability was assessed and summer temperatures shown to have greater significance in the open pile

    Enhancing anaerobic digestion in urban wastewater management

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    The thesis investigates how anaerobic digestion could be utilized to improve wastewater management,specifically in regards to future expected regulation on sludge management in Sweden.Two possible paths of applying anaerobic digestion are investigated. First, the usage of thermophilic anaerobicdigestion of sludge in order to achieve pathogen hygienization. Second, the usage of anaerobic digestion totreat wastewaters at decreased temperature. The evaluation of each path was made through practical labscale experiments. Additionally, the benefits of each path was compared through desk top environmentalimpact studies and economic analysis.The results for the first path showed that thermophilic anaerobic digestion renders high pathogen hygienizationeven at relative short exposure times. However no additional beneficial impact on biogas production or thereduction of organic micropollutants was found. The results for the second path showed that the difficulty ofoperating the sensitive anaerobic digestion process at low temperatures can be partly overcome by simpleengineering batch tests. Furthermore, the dissolved methane in the effluent wastewaters can be extractedusing membrane contactors. Finally, the environmental impact assessment showed that increased resourcerecovery from wastewater, as well as decreased climate impact, can be achieved by applying anaerobicdigestion on source separated domestic wastewaster.The economic evaluation of the two paths showed that the implementation of source separation systems isexpensive compared to implementing the needed thermophilic hygienization. However, source separationsystems would greatly boost nutrient recovery from cities to agriculture which complies well with the goals ofthe Swedish Environmental Protection Agency

    Knowledge, attitudes and practices evaluation on food hygiene and safety among perishable food handlers from a hypermarket in Portugal

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    The main objective of this study was to evaluate in loco the practices followed by the food handlers in three sections of a hypermarket, namely, butcher’s, charcuterie and fishery, as well as their level of knowledge, attitudes and practices in food hygiene and safety through the application of questionnaires. At the end it was also intended to relate the results with the training and professional experience, as well as demographic characteristics, such as sex, age and education level of food handlers. Regarding the in loco evaluation of the good personal hygiene and manufacturing practices followed by food handlers common failures were observed in the three sections studied, regarding clothing (incorrect placement of the cap and the use of adornments and jewelry), not frequent hand washing during peak flow of customers, use of cleaning and disinfecting products not indicated in the Hygienization Plan, and the use of textile fabrics. Concerning knowledge, attitudes and practices, in most situations no significant differences between the results obtained and the demographic characteristics of the food handlers were found. A high number of wrong answers were observed on topics related to microbiological knowledge and on some attitudes and hygiene practices. Therefore, these subjects should appear as priority issues in future training activities.Authors acknowledge CIMO through the Project PEst-OE/AGR/UI0690/2014info:eu-repo/semantics/publishedVersio

    Evaluation of the pH of solid residues generated in the cellulose industry adequate to the sludge hygienization for use in agriculture

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    This paper looks into the possibility of using solid residues generated in the cellulose production process to hygienize sewage sludge for fertilization. During the cellulose fabrication process, dregs, grits and vegetable biomass ashes are generated. Seven experiments were conducted in the Hydraulic Research Institute´s laboratory at UFRGS, in order to determine the pH values of the three residues in analysis-ashes, dregs, grits and the combinations of sludge/ash, sludge/grits and sludge/dregs- at the beginning (IT) and at the end (after two hours-FT). The preparation of the dregs, grits and ash solutions consisted of the weighing of 20 g of each residue and its dissolution in 80 ml of water, thus obtaining the solutions of grits, dregs and ashes. The pH values of the samples were analyzed using bench pH-meter. The ashes, grits, the mixture sludge/ash and sludge/grits displayed an accentuated basic character due to their pH values which were ≥12. The dregs and the mixture sludge/dregs presented a less accentuated basic character than the ashes and the grits, with a pH equal to 9. The results show that the ashes and the grits can be used in the hygienization of sewage sludge

    Avaliação da conformidade da prática assistencial de manutenção do cateter temporário duplo lúmen para hemodiálise

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    OBJECTIVE: to evaluate the conformity of the assistential practice in the maintenance of the temporary double-lumen catheter for hemodialysis, by means of the use of the process indicator, in the University Hospital of the University of São Paulo. METHOD: a quantitative, exploratory-descriptive and observational study. The sample was made up of 155 observations of persons with temporary double-lumen catheters, in the period March - November 2011, using the Indicator of the Maintenance of the Temporary Double Lumen Catheter for Hemodialysis. RESULTS: the rate of general conformity of the assistential practice corresponded to 65.8%. Of the practice's 13 components, 9 (69.2%) attained 100% conformity. The hygienization of hands by the professionals and the use of a mask by the patients during the disconnection from the hemodialysis had the worst rates (83.9%). CONCLUSION: although the actions evaluated are implemented in the unit, it is necessary to propose and apply educational strategies with the health team, as well as to institute periodical assessments, so as to raise the conformity rates, ensuring the quality of the hemodialysis services.OBJETIVO: evaluar la conformidad de la práctica asistencial de mantenimiento del catéter temporario duplo lumen para hemodiálisis, por medio del empleo del indicador de proceso, en el Hospital Universitario de la Universidad de Sao Paulo. MÉTODO: estudio cuantitativo, exploratorio descriptivo y observacional. La casuística se compuso de 155 observaciones de portadores de catéter temporario de duplo lumen, en el período de marzo a noviembre de 2011, empleándose el Indicador de Mantenimiento del Catéter Temporario Duplo Lumen para Hemodiálisis. RESULTADOS: el índice de la conformidad general de la práctica asistencial correspondió a 65,8%. De los 13 componentes de la práctica, 9 (69,2%) alcanzaron 100% de conformidad. La higiene de las manos por el profesional y el uso de máscara por el paciente en la desconexión de la hemodiálisis, presentaron los peores índices (83,9%). CONCLUSIÓN: a pesar de que las acciones evaluadas estén implementadas en la unidad, existe la necesidad de proponer y aplicar estrategias educativas al equipo de salud, así como instituir evaluaciones periódicas, en el sentido de elevar los índices de conformidad garantizando la calidad de los servicios en la hemodiálisis.OBJETIVO: avaliar a conformidade da prática assistencial de manutenção do cateter temporário duplo lúmen para hemodiálise, por meio do emprego do indicador de processo, no Hospital Universitário da Universidade de São Paulo. MÉTODO: estudo quantitativo, exploratório-descritivo, observacional. A casuística compôs-se de 155 observações de portadores de cateter temporário de duplo lúmen, no período de março a novembro de 2011, empregando-se o Indicador de Manutenção do Cateter Temporário Duplo Lúmen para Hemodiálise. RESULTADOS: o índice da conformidade geral da prática assistencial correspondeu a 65,8%. Dos 13 componentes da prática, 9 (69,2%) atingiram 100% de conformidade. A higiene das mãos pelo profissional e o uso de máscara pelo paciente, na desconexão da hemodiálise, apresentaram os piores índices (83,9%). CONCLUSÃO: embora as ações avaliadas estejam implementadas na unidade, há necessidade de propor e aplicar estratégias educativas à equipe de saúde, bem como instituir avaliações periódicas, no sentido de elevar os índices de conformidade garantindo a qualidade dos serviços na hemodiálise
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