968 resultados para Anaerobic waste treatment


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Mode of access: Internet.

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"Contract no. 68-03-2940."

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Photocopy of typescript.

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Mode of access: Internet.

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Generator 82 annual report; alphabetic list of hazardous waste generators -- Facility 82 annual report; alphabetic list of hazardous waste facilities.

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The spatial arrangement and metabolic activity of 'Candidatus Competibacter phosphatis' was investigated in granular sludge from an anaerobic-aerobic sequencing batch reactor enriched for glycogen-accumulating organisms. In this process, the electron donor (acetate) and the electron acceptor (oxygen) were supplied sequentially in each phase. The organism, identified by fluorescence in situ hybridisation, was present throughout the granules; however, metabolic activity was limited to a 100-mum-thick layer immediately below the surface of the granules. To investigate the cause of this, oxygen microsensors and a novel microscale biosensor for volatile fatty acids were used in conjunction with chemical staining for intracellular storage polymers. It was found that the limited distribution of activity was caused by mass transport limitation of oxygen into the granules during the aerobic phase. (C) 2003 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.

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Siloxanes are widely used in personal care and industrial products due to their low surface tension, thermal stability, antimicrobial and hydrophobic properties, among other characteristics. Volatile methyl siloxanes (VMS) have been detected both in landfill gas and biogas from anaerobic digesters at wastewater treatment plants. As a result, they are released to gas phase during waste decomposition and wastewater treatment. During transformation processes of digester or landfill gas to energy, siloxanes are converted to silicon oxides, leaving abrasive deposits on engine components. These deposits cause increased maintenance costs and in some cases complete engine overhauls become necessary. The objectives of this study were to compare the VMS types and levels present in biogas generated in the anaerobic digesters and landfills and evaluate the energetics of siloxane transformations under anaerobic conditions. Siloxane emissions, resulting from disposal of silicone-based materials, are expected to increase by 29% within the next 10 years. Estimated concentrations and the risk factors of exposure to siloxanes were evaluated based on the initial concentrations, partitioning characteristics and persistence. It was determined that D4 has the highest risk factor associated to bioaccumulation in liquid and solid phase, whereas D5 was highest in gas phase. Additionally, as siloxanes are combusted, the particle size range causes them to be potentially hazardous to human health. When inhaled, they may affix onto the alveoli of the lungs and may lead to development of silicosis. Siloxane-based COD-loading was evaluated and determined to be an insignificant factor concerning COD limits in wastewater. Removal of siloxane compounds is recommended prior to land application of biosolids or combustion of biogas. A comparison of estimated costs was made between maintenance practices for removal of siloxane deposits and installation/operation of fixed-bed carbon absorption systems. In the majority of cases, the installation of fixed-bed adsorption systems would not be a feasible option for the sole purpose of siloxane removal. However they may be utilized to remove additional compounds simultaneously.