Oxygen Control and Improved Denitrification Efficiency by Means of a Post-Anoxic Reactor

Giordano Urbini, Renato Gavasci and Paolo Viotti
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Giordano Urbini: Department of Biotechnologies and Life Sciences, University of Insubria, Via G.B. Vico 46, I-21100 Varese, Italy
Renato Gavasci: Department of Civil Engineering and Computer Science Engineering, University of Rome "Tor Vergata", Via Politecnico 1, I-00133 Roma, Italy
Paolo Viotti: Department of Civil and Environmental Engineering, University of Rome "La Sapienza", Via Eudossiana 18, I-00184 Rome, Italy

Sustainability, 2015, vol. 7, issue 2, 1-12

Abstract: The presence of dissolved oxygen (DO) in biological denitrification reactors determines inhibition effects on the denitrification rate. The article shows the results of an experimental study to control the DO concentration in the pre-denitrification stage by a post-anoxic reactor. The results demonstrate that the post-anoxic reactor is very effective in improving the nitrogen removal efficiency because it causes a considerable reduction of the DO content in the mixed liquor recycle sent to the pre-denitrification reactor. This reduction is influenced by both the retention time and the F : M ratio (referred to the denitrification and the oxidation-nitrification volume). In fact, a retention time and a F : M ratio equal to 1.5 h and 0.130 kgBOD 5 kgMLVSS −1 ·day −1 , respectively, allow to limit DO in the post-anoxic reactor at 0.31 mgO 2 ·L −1 . Such concentration determines a DO concentration of 0.11 mgO 2 ·L −1 in the pre-denitrification reactor and, consequently, a denitrification efficiency of 91%. Moreover, the contribution of the endogenous denitrification to the whole denitrification efficiency was found negligible. The paper contributes to the progress in nitrogen removal from sewage, a fundamental issue for a sustainable management of water resources.

Keywords: activated sludge; denitrification; nitrogen removal; pre-denitrification; post-denitrification; sewage treatment (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2015
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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Persistent link: https://EconPapers.repec.org/RePEc:gam:jsusta:v:7:y:2015:i:2:p:1201-1212:d:45040

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