Full-Scale Evaluation of a Hospital Wastewater Treatment Plant Upgrade: Retrofit from Extended Aeration to Moving Bed Biofilm Reactor Technology

Sadri Moghaddam, Shabnam; Mahmoudisharabiani, Hassan

doi:10.61882/NMCE.2601.1123

Full-Scale Evaluation of a Hospital Wastewater Treatment Plant Upgrade: Retrofit from Extended Aeration to Moving Bed Biofilm Reactor Technology

Document Type : Case Study

Authors

Shabnam Sadri Moghaddam ¹

Hassan Mahmoudisharabiani ²

¹ Assistant Professor, Department of Civil Engineering, K.N. Toosi University of Technology, Tehran, Iran.

² Ph.D. Candidate, Department of Civil Engineering, K.N. Toosi University of Technology, Tehran, Iran.

10.61882/NMCE.2601.1123

Abstract

This study presents a full-scale before–after evaluation of upgrading the Nikan Hospital (Tehran, Iran) wastewater treatment plant from an Extended Aeration (EA) activated-sludge process to a Moving Bed Biofilm Reactor (MBBR) by retrofitting the existing aeration tank with Kaldnes K3 carriers (40% fill) and introducing upstream screening/equalization and an anoxic zone. Over a six-month monitoring program (3 months under EA and 3 months under MBBR; composite sampling three times per week), conventional performance indicators (COD, BOD₅, NH₄⁺-N, TN, TP, and TSS) were measured and compared statistically. The results showed that the retrofit produced higher and more stable removals after start-up stabilization: COD and BOD₅ > 90%, NH₄⁺-N 70–85%, TN 65–75%, and TP 50–60%, with effluent TSS of 25–30 mg/L. Excess sludge yield decreased by 75% (0.50–0.60 to 0.12–0.15 kg VSS kg⁻¹ COD removed), lowering sludge handling frequency and contributing to an overall OPEX reduction of 35–40%. Specific aeration energy increased modestly (from 0.74 to 0.83 kWh m⁻³) due to carrier-mixing requirements, but energy intensity per kg COD removed decreased slightly because of improved removal. A first-order CSTR kinetic model was calculated from the full-scale data and was applied to estimate apparent rate constants and the HRT required to meet target effluent concentrations, supporting the observed capacity gain (effective HRT from 24 h to 9 h) within the same footprint.

Keywords

Hospital wastewater

Moving bed biofilm reactor (MBBR)

Extended aeration

Kinetic modelling

Multi-criteria assessment

Sludge reduction

Subjects

Environmental Engineering

[1] Verlicchi, P., Galletti, A., Petrovic, M., Barceló, D. (2010). Hospital effluents as a source of emerging pollutants: An overview of micropollutants and sustainable treatment options. Journal of Hydrology, 389(3–4), 416–428.

[2] Verlicchi, P., Al Aukidy, M., Zambello, E. (2015). What have we learned from worldwide experiences on the management and treatment of hospital effluent? An overview and a discussion on perspectives. Science of the Total Environment, 514, 467–491.

[3] Khan, M.T., Shah, I.A., Ihsanullah, I., Naushad, M., Ali, S., Shah, S.H.A., Mohammad, A.W. (2021). Hospital wastewater as a source of environmental contamination: An overview of management practices, environmental risks, and treatment processes. Journal of Water Process Engineering, 41, 101990

[4] Al Aukidy, M.K., Verlicchi, P., Voulvoulis, N. (2014). A framework for the assessment of the environmental risk posed by pharmaceuticals originating from hospital effluents. Science of the Total Environment, 493, 54–64.

[5] Verlicchi, P. (Ed.). (2018). Hospital Wastewaters: Characteristics, Management, Treatment and Environmental Risks. Springer, Cham.

[6] Bartoli, E., El Bachawati, M. (2025). Sustainability Assessment of Hospital Wastewater Treatment Techniques: A Comprehensive Review and Future Prospects. Sustainability, 17(11), 4930.

[7] Yuan, T., Pian, Y. (2022). Hospital wastewater as hotspots for pathogenic microorganisms spread into aquatic environment: A review. Frontiers in Environmental Science, 10, 1091734.

[8] von Sperling, M. (2007). Wastewater Characteristics, Treatment and Disposal. IWA Publishing, London, UK. https://doi.org/10.2166/9781780402086

[9] Henze, M., van Loosdrecht, M.C.M., Ekama, G.A., Brdjanovic, D. (2008). Biological Wastewater Treatment: Principles, Modelling and Design. IWA Publishing, London, UK.

[10] Tchobanoglous, G., Stensel, H.D., Tsuchihashi, R., Burton, F.L. (2014). Wastewater Engineering: Treatment and Resource Recovery (5th ed.). McGraw-Hill Education, New York, NY.

[11] Longo, S., d’Antoni, B.M., Bongards, M., Chaparro, A., Cronrath, A., Fatone, F., Lema, J.M., Mauricio-Iglesias, M., Soares, A., Hospido, A. (2016). Monitoring and diagnosis of energy consumption in wastewater treatment plants: A state of the art and proposals for improvement. Applied Energy, 179, 1251–1268.

[12] Ødegaard, H., Rusten, B., Westrum, T. (1994). A new moving bed biofilm reactor: Applications and results. Water Science and Technology, 29(10–11), 157–165.

[13] Rusten, B., McCoy, M., Proctor, R., Siljudalen, J.G. (1998). The innovative moving bed biofilm reactor/solids contact reaeration process for secondary treatment of municipal wastewater. Water Environment Research, 70(5), 1083–1089.

[14] Ødegaard, H. (2006). Innovations in wastewater treatment: The moving bed biofilm process. Water Science and Technology, 53(9), 17–33. https://doi.org/10.2166/wst.2006.284

[15] McQuarrie, J.P., Boltz, J.P. (2011). Moving bed biofilm reactor technology: process applications, design, and performance. Water Environment Research, 83(6), 560–575.

[16] Leyva-Díaz, J.C., Monteoliva-García, A., Martín-Pascual, J., Munio, M.M., García-Mesa, J.J. (2020). Moving bed biofilm reactor as an alternative wastewater treatment process for nutrient removal and recovery in the circular economy model. Bioresource Technology,299,122631.

[17] Hem, L.J., Rusten, B., Ødegaard, H. (1994). Nitrification in a moving bed biofilm reactor. Water Research, 28, 1425–1433.

[18] Rusten, B., Hem, L.J., Ødegaard, H. (1995). Nitrogen removal from dilute wastewater in cold climate using moving-bed biofilm reactors. Water Environment Research, 67(1), 65–74.

[19] Rusten, B., Hem, L.J., Ødegaard, H. (1995). Nitrification of municipal wastewater in moving-bed biofilm reactors. Water Environment_Research,67(1),75–86.

[20] Rusten, B., Eikebrokk, B., Ulgenes, Y., Lygren, E. (2006). Design and operations of the Kaldnes moving bed biofilm reactors. Aquacultural Engineering, 34(3), 322–331.

[21] Ooi, G.T.H., Tang, K., Chhetri, R.K., Kaarsholm, K.M.S., Sundmark, K., Kragelund, C., Litty, K., Christensen, A., Lindholst, S., Sund, C., Christensson, M., Bester, K., Andersen, H.R. (2018). Biological removal of pharmaceuticals from hospital wastewater in a pilot-scale staged moving bed biofilm reactor (MBBR) utilising nitrifying and denitrifying processes. Bioresource Technology, 267, 677–687.

[22] Escolà Casas, M., Chhetri, R.K., Ooi, G.T.H., Kaarsholm, K.M.S., Litty, K., Christensson, M., Kragelund, C., Andersen, H.R., Bester, K. (2015). Biodegradation of pharmaceuticals in hospital wastewater by staged Moving Bed Biofilm Reactors (MBBR).Water_Research,83,293–302.

[23] Regmi, P., Thomas, W., Schafran, G., Bott, C., Rutherford, B., Waltrip, D. (2011). Nitrogen removal assessment through nitrification rates and media biofilm accumulation in an IFAS process demonstration study. Water Research, 45(20), 6699–6708.

[24] Barry, U., Choubert, J.-M., Canler, J.-P., Pétrimaux, O., Héduit, A., Lessard, P. (2017). A one dimensional moving bed biofilm reactor model for nitrification of municipal wastewaters. Bioprocess and Biosystems Engineering, 40, 1141–1149.

[25] McQuarrie, J.P., Boltz, J.P., Daigger, G.T. (2010). Interactions between suspended biomass and biofilm in integrated fixed-film activated sludge (IFAS) bioreactors: Process design implications for IFAS systems. Proceedings of the Water Environment Federation, WEFTEC 2010, 2010(7), 197–211.

[26] APHA/AWWA/WEF. (2017). Standard Methods for the Examination of Water and Wastewater (23rd ed.). American Public Health Association, American Water Works Association, Water Environment Federation, Washington, DC.

[27] Shokoohi, R., Asgari, G., Leili, M., Khiadani, M., Foroughi, M., Sedighi Hemmat, M. (2017). Modelling of moving bed biofilm reactor (MBBR) efficiency on hospital wastewater (HW) treatment: A comprehensive analysis on BOD and COD removal. International Journal of Environmental Science and Technology, 14, 841–852.

[28] WHO. (2006). Guidelines for the Safe Use of Wastewater, Excreta and Greywater. Volume 2: Wastewater Use in Agriculture. World Health Organization, Geneva, Switzerland.

[29] Sabet, H., Sadri Moghaddam, S., Ehteshami, M. (2023). A comparative life cycle assessment (LCA) analysis of innovative methods employing cutting-edge technology to improve sludge reduction directly in wastewater handling units. Journal of Water Process Engineering, 51, 103354.

[30] Falletti, L., Conte, L., Maestri, A. (2014). Upgrading of a wastewater treatment plant with a hybrid moving bed biofilm reactor (MBBR). AIMS Environmental Science, 1(2), 45–52.

[31] Qaderi, F., Ayati, B., & Ganjidoust, H. (2011). Role of moving bed biofilm reactor and sequencing batch reactor in biological degradation of formaldehyde wastewater. Journal of Environmental Health Science and Engineering, 8, 295–306.

[32] Qaderi, F., Sayahzadeh, A. H., & Azizi, M. (2018). Efficiency optimization of petroleum wastewater treatment by using serial moving bed biofilm reactors. Journal of Cleaner Production, 192, 665–677.

[33] Babanezhad, E., Amini Rad, H., Hosseini Karimi, S. S., & Qaderi, F. (2017). Investigating nitrogen removal using simultaneous nitrification–denitrification in transferring wastewater through collection networks with small-diameter pipes. Water Practice and Technology, 12, 396–405.

[34] Qaderi, F., Sayahzadeh, A. H., Azizpour, F., & Vosughi, P. (2019). Efficiency modeling of serial stabilization ponds in treatment of phenolic wastewater by response surface methodology. International Journal of Environmental Science and Technology, 16(8), 4193–4202.

[35] Asadi, P., Amini Rad, H., & Qaderi, F. (2019). Comparison of Chlorella vulgaris and Chlorella sorokiniana PA.91 in post-treatment of dairy wastewater treatment plant effluents. Environmental Science and Pollution Research.

[36] Qaderi, F., Sayahzadeh, A. H., & Ebrahimi Ghadi, M. (2019). Optimization of effective environmental parameters on Astrazon Red GTL removal by dominant species Bacillus and Aeromonas: in a concurrent culture study. Journal of Molecular and Cellular Research, 32(1), 1–15.

[37] Gupta, B., Gupta, A. K., Ghosal, P. S., Lal, S., & Upadhyay, M. (2022). Recent advances in application of moving bed biofilm reactor for wastewater treatment: insights into critical operational parameters, modifications, field-scale performance, and sustainable aspects. Journal of Environmental Chemical Engineering, 10(3), 107742.

[38] Bhandari, G., Chaudhary, P., Gangola, S., Gupta, S., Gupta, A., Rafatullah, M., & Chen, S. (2023). A review on hospital wastewater treatment technologies: Current management practices and future prospects. Journal of Water Process Engineering, 56, 104516.