Simultaneous nitrification-denitrification in SBR with floating EPS carriers for dairy wastewater
DOI:
https://doi.org/10.36910/6775-2410-6208-2026-15(25)-09Keywords:
simultaneous nitrification-denitrification, IFAS-SBR, expanded polystyrene, biofilm, ASM3, dairy wastewaterAbstract
The article presents the results of an experimental study and mathematical modelling of simultaneous nitrification-denitrification (SND) in an IFAS-SBR system with floating expanded polystyrene (EPS) carriers for treatment of dairy wastewater characterised by a low C/N ratio of 3.0–3.5. The relevance of the study is justified by the need to comply with EU Council Directive 91/271/EEC concerning nitrogen discharges and by the lack of systematic data in the literature on the performance of IFAS systems in the C/N < 4 range typical for dairy wastewater. Two parallel laboratory reactors — one loaded with 30 % by volume of EPS carriers (specific surface area 550 m²/m³, granule diameter 3–5 mm) and a control reactor without EPS — were compared using real wastewater from the SE «Ruzhyn-Moloko» dairy enterprise (capacity 300 m³/day) during 2023–2024 at a stable temperature of 20 °C, MLSS = 3.5 g/L and an SBR cycle duration of 6 h. The optimal range of dissolved oxygen concentration was determined as DO = 0.8–1.2 mg/L (with the maximum efficiency at DO = 1.0 mg/L), at which a stable two-layer biofilm structure is formed: an outer aerobic layer (0–100 µm) hosting nitrifiers and an inner anoxic layer (100–300 µm) hosting denitrifiers. Total nitrogen removal efficiency reached 86.5 % (compared to 76.0 % in the control reactor without EPS); effluent concentrations of NH₄⁺-N = 1.5 mg/L and TN = 6.5 mg/L meet the requirements of DSTU 7525:2014. Operation under low DO conditions reduced specific aeration energy consumption by 37.5 % compared to conventional schemes. The process was described by the modified activated sludge model ASM3_2N verified in AQUASIM 2.0 with RMSE ≤ 12.3 % and NSE ≥ 0.86. The obtained results may be used for the design and modernisation of local wastewater treatment plants of small and medium capacity at dairy processing enterprises.
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References
1. European Environment Agency. European waters: assessment of status and pressures 2018 : EEA Report No 7/2018. Luxembourg : Publications Office of the European Union, 2018. 90 p.
2. Директива Ради 91/271/ЄЕС від 21.05.1991 про очистку міських стічних вод. Офіційний вісник Європейських Співтовариств. 1991. L 135/40. 8 с.
3. Henze M., van Loosdrecht M.C.M., Ekama G.A., Brdjanovic D. Biological Wastewater Treatment: Principles, Modelling and Design. London : IWA Publishing, 2008. 528 p. URL: https://doi.org/10.2166/9781780401867
4. Pochana K., Keller J. Study of factors affecting simultaneous nitrification and denitrification (SND). Water Science and Technology. 1999. Vol. 39, № 6. P. 61–68. URL: https://doi.org/10.2166/wst.1999.0259
5. Liu Y., Tay J.-H. The essential role of hydrodynamic shear force in the formation of biofilm and granular sludge. Water Research. 2002. Vol. 36, № 7. P. 1653–1665. URL: https://doi.org/10.1016/S0043-1354(01)00379-7
6. Germain E., Bancroft L., Dawson A., Hinton C., Holloway J., Pearce P. Evaluation of hybrid processes for nitrification by comparing MBBR/AS and IFAS configurations. Water Science and Technology. 2007. Vol. 55, № 8–9. P. 43–49. URL: https://doi.org/10.2166/wst.2007.240
7. McQuarrie J.P., Boltz J.P. Moving bed biofilm reactor technology: process applications, design, and performance. Water Environment Research. 2011. Vol. 83, № 6. P. 560–575. URL: https://doi.org/10.2175/106143010X12851009156286
8. Rusten B., Ødegaard H. Nitrogen removal in moving-bed biofilm reactor plants at low temperatures: experiences from Norway. Water Science and Technology. 2023. Vol. 87, № 10. P. 2432–2440. URL: https://doi.org/10.2166/wst.2023.154
9. Bhattacharya R., Mazumder D. Performance evaluation of moving bed bioreactor for simultaneous nitrification denitrification and phosphorus removal. Environmental Science and Pollution Research. 2023. Vol. 30, № 17. P. 49060–49074. URL: https://doi.org/10.1007/s11356-023-25708-z
10. Bhattacharya R., Mazumder D. Development of a simplistic mathematical model for SND in moving bed bioreactor. Environmental Modeling & Assessment. 2023. Vol. 28, № 5. P. 873–887. URL: https://doi.org/10.1007/s10666-023-09874-5
11. Münch E.V., Lant P., Keller J. Simultaneous nitrification and denitrification in bench-scale sequencing batch reactors. Water Research. 1996. Vol. 30, № 2. P. 277–284. URL: https://doi.org/10.1016/0043-1354(95)00200-6
12. Lúcio D.S.G., Dias M.E.S., Ribeiro R., Tommaso G. Evaluating the potential of a new reactor configuration to enhance simultaneous organic matter and nitrogen removal in dairy wastewater treatment. Environmental Science and Pollution Research. 2023. Vol. 30. P. 56741–56755. URL: https://doi.org/10.1007/s11356-023-26341-6
13. Metcalf & Eddy Inc., Tchobanoglous G., Stensel H.D., Tsuchihashi R., Burton F. Wastewater Engineering: Treatment and Resource Recovery. 5th ed. New York : McGraw-Hill, 2014. 2048 p.
14. ДСТУ EN ISO 5667-3:2025. Якість води. Відбирання проб. Частина 3. Консервування та поводження зі зразками води. Київ : ДП «УкрНДНЦ», 2025. 35 с.
15. ДСТУ 7525:2014. Вода питна. Вимоги та методи контролювання якості. Київ : Мінекономрозвитку України, 2014. 25 с.
16. Iacopozzi I., Innocenti V., Marsili-Libelli S., Giusti E. A modified Activated Sludge Model No. 3 (ASM3) with two-step nitrification-denitrification. Environmental Modelling & Software. 2007. Vol. 22, № 6. P. 847–861. URL: https://doi.org/10.1016/j.envsoft.2006.04.008
17. Monod J. The growth of bacterial cultures. Annual Review of Microbiology. 1949. Vol. 3. P. 371–394. URL: https://doi.org/10.1146/annurev.mi.03.100149.002103
