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Phosphorus release during treatment of sludge derived from a bench-scale EBPR plant

This thesis describes the development of enhanced biological phosphorus removal (EBPR) in a lab-scale sequencing batch reactor (SBR) and the release of phosphorus during the storage and thickening of sludge produced in this reactor. In the first phase of the experimental work a fast start-up method for EBPR development was established by the addition of a pure culture of Acinetobacter lwoffi to a conventional activated sludge. Investigations revealed that the performance EBPR depended on the combination of influent COD and phosphorus values and that in the investigated range, EBPR functioned independently of the sludge retention time. Low dissolved oxygen levels had no effect on the phosphorus removal properties of the sludge. The second phase of the experimental work involved the investigation of the phosphorus released during sludge handling. It was found that phosphorus resolubilisation during sludge treatment took place in three distinct phases which included an initial period of extremely low phosphorus release. Alterations of the reactor influent and operational parameters and the sludge characteristics, affected the amount of phosphorus released during anaerobic storage and gravity thickening. It was found that for short retention times in the sludge processing units (1-48 hours), decreasing the influent phosphorus concentration, increasing the oxidised nitrogen content of the excess sludge and wasting the excess sludge from the aeration tank decreased the amount of phosphorus resolubilised. For longer retention times (2-7 days), it was found that increasing the influent COD, having a lower total phosphorus sludge content, higher sludge "stabilisation" rates and quiescent conditions of storage, decreased the amount of phosphorus released.

Identiferoai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:339045
Date January 2002
CreatorsBelia, Evangelia
PublisherUniversity of Strathclyde
Source SetsEthos UK
Detected LanguageEnglish
TypeElectronic Thesis or Dissertation
Sourcehttp://digitool.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=28864

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