Role of Solids Retention Time in Ammonia-Based Feedback Aeration Control
Publication: Journal of Environmental Engineering
Volume 142, Issue 7
Abstract
Ammonia-based feedback aeration control could avoid an unnecessary air supply and, therefore, save energy. However, this control method could be impacted by many factors such as solids retention time (SRT), nitrite oxidation rate, dissolved oxygen (DO) variation, influent load, temperature, and regular low DO operation. This study indicated that, with an unlimited DO (), the minimal SRT required to achieve complete nitrification was between 5 and 10 days. If the SRT was , reducing the DO could result in accumulation of nitrite. Nitrite could also accumulate under a peak ammonia load with a SRT of less than 15 days. In contrast, ammonia-based feedback control resulted in regular low DO operation. Because low DO enriches nitrifiers and selects nitrite-oxidizing bacteria (NOB) with a greater oxygen affinity, the required SRT to avoid the accumulation of nitrite can be substantially reduced. The authors recommend using a minimal SRT of 20 days to start a system. When the system reaches a stable condition, the minimal SRT can be reduced to 15 days, if needed. A pilot-scale field experiment indicated that the adverse effect of a low temperature can be overcome by extending the SRT.
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Acknowledgments
This research was partially supported by a grant from the Army Research Lab (ARL) through Leonard Wood Institute (LWI) and Frontier Environmental Technology, LLC. Other supports from the Environmental Research Center (ERC) at Missouri University of Science and Technology (Missouri S&T) and from the Rolla Southeast Wastewater Treatment Plant are greatly appreciated.
At the time this research was initially conducted, Guoqiang Liu was a Graduate Research Assistant at Missouri S&T. On receiving his Ph.D., Guoqiang Liu’s appointment has changed to Senior Research Engineer at Frontier Environmental Technology and Adjunct Assistant Professor at Missouri S&T while working on the same research.
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Published In
Journal of Environmental Engineering
Volume 142 • Issue 7 • July 2016
Copyright
© 2016 American Society of Civil Engineers.
History
Received: Dec 4, 2014
Accepted: Dec 1, 2015
Published online: Feb 18, 2016
Published in print: Jul 1, 2016
Discussion open until: Jul 18, 2016
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