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Water Res. 2017 Sep 15;121:72-85. doi: 10.1016/j.watres.2017.05.029. Epub 2017 May 13.

Pilot plant demonstration of stable and efficient high rate biological nutrient removal with low dissolved oxygen conditions.

Author information

1
Department of Civil and Environmental Engineering, University of Wisconsin-Madison, USA. Electronic address: natkee25@gmail.com.
2
Madison Metropolitan Sewerage District, USA. Electronic address: reu2015@att.net.
3
Department of Civil and Environmental Engineering, University of Wisconsin-Madison, USA. Electronic address: scarborough.matthew@gmail.com.
4
Madison Metropolitan Sewerage District, USA. Electronic address: alang@madsewer.org.
5
Madison Metropolitan Sewerage District, USA. Electronic address: matts@madsewer.org.
6
Water Supply and Water Resources Division, Environmental Protection Agency, Cincinnati, OH, USA. Electronic address: santodomingo.jorge@epa.gov.
7
Department of Civil and Environmental Engineering, University of Wisconsin-Madison, USA. Electronic address: noguera@engr.wisc.edu.

Abstract

Aeration in biological nutrient removal (BNR) processes accounts for nearly half of the total electricity costs at many wastewater treatment plants. Even though conventional BNR processes are usually operated to have aerated zones with high dissolved oxygen (DO) concentrations, recent research has shown that nitrification can be maintained using very low-DO concentrations (e.g., below 0.2 mg O2/L), and therefore, it may be possible to reduce energy use and costs in BNR facilities by decreasing aeration. However, the effect of reduced aeration on enhanced biological phosphorus removal (EBPR) is not understood. In this study, we investigated, at the pilot-scale level, the effect of using minimal aeration on the performance of an EBPR process. Over a 16-month operational period, we performed stepwise decreases in aeration, reaching an average DO concentration of 0.33 mg O2/L with stable operation and nearly 90% phosphorus removal. Under these low-DO conditions, nitrification efficiency was maintained, and nearly 70% of the nitrogen was denitrified, without the need for internal recycling of high nitrate aeration basin effluent to the anoxic zone. At the lowest DO conditions used, we estimate a 25% reduction in energy use for aeration compared to conventional BNR operation. Our improved understanding of the efficiency of low-DO BNR contributes to the global goal of reducing energy consumption during wastewater treatment operations.

KEYWORDS:

Accumulibacter; BNR; Dissolved oxygen; EBPR; Energy reduction; Nitrification

PMID:
28521237
DOI:
10.1016/j.watres.2017.05.029
[Indexed for MEDLINE]

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