https://doi.org/10.15255/KUI.2024.057
Published: Kem. Ind. 74 (7-8) (2025) 301–310
Paper reference number: KUI-57/2024
Paper type: Original scientific paper
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Nitrogen and Phosphorus Removal from Low Carbon/Nitrogen Wastewater in an Anaerobic/Oxic/Anoxic Process with Endogenous Denitrification at Different DO Concentrations

T. Štefanac, D. Grgas, I. Landeka Jurčević, S. Radman, M. Habuda-Stanić and T. Landeka Dragičević

Abstract

The effect of selected dissolved oxygen (DO) concentrations (DO ≥ 2 mg l⁻¹ and DO ≈ 1 mg l⁻¹) on nitrogen (N) and phosphorus (P) removal was investigated in the treatment of wastewater with a low C/N ratio using an anaerobic/oxic/anoxic (A/O/A) process with endogenous denitrification. The selected DO significantly influenced the efficiency and rate of N removal. The N loss of 43 and 71 %, due to simultaneous nitrification and denitrification in the oxic phase of the A/O/A process, were observed at ≥ 2 mg DO l⁻¹ and ≈ 1 mg DO l⁻¹, respectively. The NH₄-N removal rate of 11.2 mg NH₄-N lh⁻¹ and the PO₄-P uptake rate of 9 mg PO₄-P lh⁻¹, and NH₄-N removal rate of 9.4 mg NH₄-N lh⁻¹ and PO₄-P uptake rate of 9.4 mg PO₄-P lh⁻¹ at ≥ 2 mg DO l⁻¹ and ≈ 1 mg DO l⁻¹, were determined. P removal of 78.5 % and N removal of 76.6 % (in the A/O/A process at DO ≥ 2 mg l⁻¹), and P removal of 77.9 % and N removal of 95.3 % (in the A/O/A process at DO ≈ 1 mg l⁻¹) were achieved.

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Keywords

nitrification, denitrification, phosphorus removal, endogenous denitrification, dissolved oxygen, wastewater with low C/N ratio