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Aerating a High Rate Low SRT Activated Sludge Reactor: Coarse or Fine Bubble Aeration---How About a Hybrid?

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The Western Branch wastewater treatment plant (WWTP) has four parallel trains of identically sized complete-mix high rate activated sludge (HRAS) treatment processes, each maintaining a solids retention time (SRT) less than two days treating wastewater receiving no primary treatment. One treatment train uses coarse bubble aeration while the other three use fine bubble. The coarse bubble train and one of the fine bubble trains were investigated relative to process performance, aeration, and maintenance requirements. The coarse and fine bubble alphas were estimated at about 0.59 and 0.30, respectively. It has been estimated that a coarse to fine bubble retrofit results in a decrease in aeration requirements of about 25%, which is substantially less than what can be expected from a similar retrofit for a low rate, long SRT process that treats primary effluent. It has been estimated that a 9% decrease in aeration requirements can be expected by operating the first zone of a kinetics-based staged selector reactor anaerobically.

Keywords: Aeration; alpha; coarse bubble; fine bubble; standard oxygen transfer efficiency

Document Type: Research Article


Publication date: January 1, 2009

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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 These proceedings are not peer reviewed.

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