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A combination of dye tests and simulations were conducted to characterize the process characteristics of a four-pass activated sludge aeration tank. The dye tests found that the tank had a more plug flow character than would have been expected from its geometry alone. The more pronounced plug flow character is considered by the authors to be the result of internal mixing in the tanks caused by fine bubble aeration. Simulations using the BioWin™ software were conducted to compare the process characteristics of tanks with different number of tanks-inseries. It was concluded that, even though the dye tests indicated that the tank under study had an equivalent number of tanks over 50, a 12-celled model could adequately explain available data. A custom carbon removal process model was developed to predict the impact of control from different locations within the tank on airflows and dissolved oxygen distribution. It was concluded that control of the tanks at two points, one in the middle of the four-pass tank and the second at the end of the tank, produced the best combination of low airflow and relatively even dissolved oxygen distribution.

Document Type: Research Article


Publication date: January 1, 2004

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  • Proceedings of the Water Environment Federation is an archive of papers published in the proceedings of the annual Water Environment Federation® Technical Exhibition and Conference (WEFTEC® ) and specialty conferences held since the year 2000. These proceedings are not peer reviewed.

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