The Fate of Heavy Metals in Pilot-Plant Scale Upflow Sludge-Blanket Clarifiers |
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| Authors: | M HUNTER BSc PhD MIBiol T STEPHENSON BSc PhD MIBiol MRSC J N LESTER MSc PhD MIBiol |
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| Affiliation: | Dr Hunter is a Post Doctoral Research Assistant in Public Health Engineering. and Dr Lester is Reader in Public Health Engineering. Department of Civil Engineering. Imperial College of Science and Technology, London. Dr Stephenson is Senior Lecturer in Biochemical Engineering. North East Biotechnology Centre. Department of Chemical Engineering. Teesside Polytechnic: Mid-dlesbrought: he was formerly at Imperial College. |
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| Abstract: | T he R emoval of heavy metals and aluminium residuals during upflow sludge-blanket clarification was investigated using a pilot-plant system. Pilot units treating predosed raw water on site were assessed for sludge-blanket formation and stabilization, and were found to produce clarified water of a comparable quality to the main works units after the start-up and stabilization periods were complete. The heavy metals Cr, Fe, Mn, and Ni were the only heavy metals detectable at the investigation site and these occurred at concentrations well below guidelines values for potable abstraction and supply.
Mean removals of Fe, Mn, Cr, and Ni were about 98, 89, 51, and 30 per cent respectively, during steady-state operation, and Fe, Mn, and Cr all displayed reduced removals during transient changes in surface load, whereas Ni removal appeared to be relatively independent. Aluminium residuals derived from the dosed alum coagulant also showed decreases in removal from about 83 per cent during steady-state operation to between 40 and 50 per cent during transient experiments. |
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