Original scientific paper

https://doi.org/10.15255/KUI.2024.034

Denitrifying Dephosphatation via Nitrite under Anoxic Conditions

Andrijana Brozinčević orcid.org/0009-0008-0053-7306 ; Plitvice Lakes National Park, Dr. Ivo Pevalek Scientific Research Centre, Josipa Jovića 19, 53 231 Plitvička Jezera, Croatia
Dijana Grgas orcid.org/0000-0003-0687-6524 ; University of Zagreb, Faculty of Food Technology and Biotechnology, Pierottijeva 6, 10 000 Zagreb, Croatia *
Irena Landeka Jurčević ; University of Zagreb, Faculty of Food Technology and Biotechnology, Pierottijeva 6, 10 000 Zagreb, Croatia
Mirna Habuda-Stanić orcid.org/0000-0002-0089-9488 ; J. J. Strossmayer University of Osijek, Faculty of Food Technology Osijek, F. Kuhača 18, 31 000 Osijek, Croatia
Bruno Zelić orcid.org/0000-0003-3210-2960 ; University of Zagreb Faculty of Chemical Engineering and Technology, Trg Marka Marulića 19, 10 000 Zagreb, Croatia
Tibela Landeka Dragičević ; University of Zagreb, Faculty of Food Technology and Biotechnology, Pierottijeva 6, 10 000 Zagreb, Croatia

* Corresponding author.

Abstract

Denitrifying dephosphatation is a cost-effective method for simultaneously removing nitrogen and phosphorus due to its lower chemical oxygen demand (COD) requirement, reduced aeration, and decreased sludge production. In batch experiments, denitrifying dephosphatation of 20 ± 1 mg PO₄-P/l using nitrite was studied at N/P ratios of 2, 3, and 4. The effects of both limiting and non-limiting COD, provided by sodium acetate as a carbon source, on the activity of denitrifying phosphorus-accumulating organisms (DPAOs) were investigated. In all batch tests, at ratios N/P of 2, 3, 4, increasing the C/N ratio led to higher NO₂-N and P removal rates and efficiencies. In all batch tests, at ratios N/P of 2, 3, 4, the highest denitrification and anoxic phosphorus uptake rates were recorded under the following conditions: at C/N ratio of 4 and N/P ratio of 2, C/N ratio of 3 and N/P ratio of 3, and C/N ratio of 2 and N/P ratio of 4. In tests with limited carbon sources (N/P of 2 and C/N < 4, N/P of 3 and C/N < 3, and N/P of 4 and C/N < 2), both denitrification and P uptake rates and efficiencies increased with rising C/N ratios. However, the batch tests with COD overdose resulted in increased denitrification rate but deteriorated P removal rate and efficiency. In the tests with a C/N ratio of 7, the P removal efficiencies were 75 ± 3 %, 68 ± 2 %, and 62 ± 4 % at N/P ratios of 2, 3, and 4, respectively.

Keywords

denitrification; nitrite; phosphate uptake; anoxic conditions; denitrifying phosphorus-accumulating organisms

Hrčak ID:

327848

URI

https://hrcak.srce.hr/327848

Publication date:

18.3.2025.

Article data in other languages: croatian

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