Magnesium requirement for biological removal of phosphate by activated sludge |
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| Institution: | 1. Department of Chemical Process Engineering, Faculty of Engineering, Hokkaido University, Sapporo 060, Japan;2. Nippon Light Metal Company Ltd., Miho, Shimizu 424, Japan;1. Department of Environmental and Natural Resources Management, School of Engineering, University of Patras, 2 Seferi Str., 30100 Agrinio, Greece;2. Università di Napoli Federico II, Centro Interdipartimentale di Ricerca sulla Risonanza Magnetica Nucleare (CERMANU), Via Università 100, 80055 Portici, Italy;3. Department of Physics, University of Ioannina, 45110 Ioannina, Greece;1. Department of Plant Production, Desert Research Center, Cairo, Egypt;2. Department of Genetics, Faculty of Agriculture and Natural Resources, University of Aswan, Aswan, Egypt;1. Plateforme d''Analyse Moléculaire Biodiversité-Environnement, IUT, 85035 La Roche sur Yon, France;2. IRSTV-AGROCAMPUS OUEST, UP EPHor, 49042 Angers, France;3. FLORENTAISE company, 44850 Saint-Mars du Désert, France;4. UMR 6112CNRS, LPG, 44322 Nantes, France;1. Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA, United Kingdom;2. Department of Civil, Environmental Geomatic Engineering, ETH Zurich, Stefano-Franscini-Platz 5, 8093 Zurich, Switzerland;1. Department of Physics, University of Allahabad, Allahabad, India;2. Department of Biochemistry, University of Allahabad, Allahabad, India;3. School of Materials Science and Technology, Indian Institute of Technology, Banaras Hindu University, Varanasi, India;4. Department of Applied Chemistry, University of Johannesburg, Johannesburg 2028, South Africa;1. Laboratory of Plant Pathology, Area of Sustainable Crop Protection, Andalusian Institute of Agricultural Research and Training (IFAPA), Centro ‘Alameda del Obispo’, Apartado 3092, 14080 Córdoba, Spain;2. Department of Agricultural and Forestry Sciences and Resources, University of Cordoba, Spain |
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| Abstract: | The effects of magnesium on excess uptake of phosphate in an aerobic-anaerobic activated sludge process were examined by the fill and draw procedure. The alternation of anaerobic and aerobic conditions in one cycle of fill and draw process was varied many ways.The presence of sufficient magnesium was necessary for uptake of excess phosphate. When sludge contained more phosphorus than the upper limit of phosphorus content in the usual aerobic activated sludge, 2.5% by weight, magnesium was also contained in more than an ordinary amount (0.5%). Their contents in the sludge at the end of each cycle of the process were correlated with each other by a linear equation with the correlation coefficient of 0.99. When magnesium concentration was insufficient for the uptake of excess phosphate, its concentration in the treated water was of the order of 0.1 mg/l.In the first anaerobic period both phosphate and magnesium were released, and in a successive aerobic period they were taken up again. The weight ratio of differential amounts of phosphorus and magnesium released or taken up changed with time in one cycle.Dynamic behaviors of phosphate and magnesium removal against the step change of feed magnesium concentration also showed a stoichiometric relationship supporting the correlation equation above mentioned. |
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