Comparison of technical and economic efficiency of extended aeration and sequencing batch reactors processes in hospital wastewater treatment

Document Type : Original Article


1 Health Center of Gorgan, Gorgan, Iran

2 Department of Environmental Health Engineering, Environmental Health Research Center, School of Health AND Cereal Health Research Center, Golestan University of Medical Sciences, Gorgan, Iran

3 Environmental Health Research Center, Golstan University of Medical Sciences, Gorgan, Iran

4 Hakim Jorjani Hospital, Gorgan, Iran

5 Manager of Falsafi Hospital, Gorgan, Iran

6 Health Center of Aq Qala, Golestan, Iran

7 Pazhab Tadbir Consulting Engineers, Gorgan, Iran


Wastewater of hospitals can cause many risks to public health due to having a variety of pathogenic microorganisms, pharmaceutical substances, and other hazardous toxic substances. The aim of this study was to evaluate the chemical quality of effluents from wastewater treatment plant of Falsafi Hospital and Hakim Jorjani Hospital in Gorgan, Iran, and to compare them technically and economically. This descriptive-analytical study was performed on 64 samples of raw wastewater entrance and output effluent obtained from treatment plants using extended aeration process and sequencing batch reactors (SBR) in two hospitals in Gorgan. All experiments for determination of pH, free residual chlorine, biochemical oxygen demand (BOD), chemical oxygen demand (COD), and total suspended solids (TSS) were performed using standard methods. Finally, the obtained data were analyzed using t-test and Mann-Whitney test in SPSS software. Based on the results, the removal efficiency of BOD, COD, and TSS of the extended aeration system was 91, 90.8, and 95.7 percent, respectively, while these values for the SBR system were found to be 91.7, 91.9, and 95.3 Percent, respectively. Moreover, in the output of the two hospitals, pH values were recorded as 6.69 ± 0.26 and 7.33 ± 0.2 and the average amount of free residual chlorine was 0.12 and 0.13 mg/l, respectively. This study demonstrates good performances of the extended aeration activated sludge system and the SBR system in terms of reduction of pollution load to its standard limits for agriculture and irrigation purposes. However, due to slightly better efficiency, lower cost of investment, and operation compared to other methods, the SBR system is recommended. 


1. Amouei A, Asgharnia HA, Mohammadi AA, Fallahm H, Dehghani R, Miranzadeh MB. Investigation of hospital wastewater treatment plant efficiency in north of Iran during 2010-2011. International Journal of Physical Sciences 2012; 7(31): 5213-7.
2. Lin AY, Wang XH, Lin CF. Impact of wastewaters and hospital effluents on the occurrence of controlled substances in surface waters. Chemosphere 2010; 81(5): 562-70.
3. Kovalova L, Siegrist H, von Gunten U, Eugster J, Hagenbuch M, Wittmer A, et al. Elimination of micropollutants during post-treatment of hospital wastewater with powdered activated carbon, ozone, and UV. Environ Sci Technol 2013; 47(14): 7899-908.
4. Rezaee A, Ansari M, Khavanin A, Sabzali A, Aryan M. Hospital Wastewater Treatment Using an Integrated Anaerobic Aerobic Fixed Film Bioreactor. Am J Environ Sci 2005; 1(4): 259-63.
5. Fijan S, Poljsak-Prijatelj M, Steyer A, Koren S, Cencic A, Sostar-Turk S. Rotaviral RNA found in wastewaters from hospital laundry. Int J Hyg Environ Health 2006; 209(1): 97-102.
6. Luo Y, Guo W, Ngo HH, Nghiem LD, Hai FI, Zhang J, et al. A review on the occurrence of micropollutants in the aquatic environment and their fate and removal during wastewater treatment. Sci Total Environ 2014; 473-474: 619-41.
7. Prado T, Silva DM, Guilayn WC, Rose TL, Gaspar AM, Miagostovich MP. Quantification and molecular characterization of enteric viruses detected in effluents from two hospital wastewater treatment plants. Water Res 2011; 45(3): 1287-97.
8. Kajitvichyanukul P, Suntronvipart N. Evaluation of biodegradability and oxidation degree of hospital wastewater using photo-Fenton process as the pretreatment method. J Hazard Mater 2006; 138(2): 384-91.
9. De Witte B, Van Langenhove H, Demeestere K, Saerens K, De Wispelaere P, Dewulf J. Ciprofloxacin ozonation in hospital wastewater treatment plant effluent: effect of pH and H2O2. Chemosphere 2010; 78(9): 1142-7.
10. Liu Q, Zhou Y, Chen L, Zheng X. Application of MBR for hospital wastewater treatment in China. Desalination 2010; 250(2): 605-8.
11. Yang Z, Zeng G, Gao F, Chen J. Study on Piggery Wastewater Treatment by Screening-UASB-SBR Processes. Journal of Hunan University (Naturnal Science) 2002; (29): 95-9.
12. World Health Organization. Guidelines for the safe use of wastewater, excreta and greywater - Volume 1: Policy and regulatory aspects [Online]. [cited 2006]; Available from: URL: 2016.
13. Tchobanoglous G, Burton FL, Stensel D. Wastewater engineering: treatment and reuse. New York, NY: McGraw-Hill Education; 2003.
14. Yuan S, Jiang X, Xia X, Zhang H, Zheng S. Detection, occurrence and fate of 22 psychiatric pharmaceuticals in psychiatric hospital and municipal wastewater treatment plants in Beijing, China. Chemosphere 2013; 90(10): 2520-5.
15. Gros M, Rodriguez-Mozaz S, Barcelo D. Rapid analysis of multiclass antibiotic residues and some of their metabolites in hospital, urban wastewater and river water by ultra-high-performance liquid chromatography coupled to quadrupole-linear ion trap tandem mass spectrometry. J Chromatogr A 2013; 1292: 173-88.
16. Golbabaei Kootenaei F, Amini Rad H. Bioreactor Membrane Filtration-Nano Novel by Wastewater
Hospital of Treatment. Iranica J Energy & Environ 2013; 4(1): 60-7.
17. Sarafraz S, Khani MR, Yaghmaeian K. Quality and quantity survey of hospital wastewaters in Hormozgan province. Iran Environ Health Sci Eng 2007; 4(1): 43-50.
18. Fernandes H, Jungles MK, Hoffmann H, Antonio RV, Costa RH. Full-scale sequencing batch reactor (SBR) for domestic wastewater: performance and diversity of microbial communities. Bioresour Technol 2013; 132: 262-8.
19. Eaton AD, Franson MA. Standard Methods for the Examination of Water & Wastewater. Washington, DC: American Public Health Association; 2005.
20. Meo MI, Haydar S, Nadeem O, Hussain G, Rashid H. Characterization of hospital wastewater,risk waste generation and management practices in lahore. Proceedings of the Pakistan Academy of Sciences 2014; 51(4): 317-9.
21. Majlesi Nasr M, Yazdanbakhsh AR. Study on wastewater treatment systems in hospitals of Iran. J Environ Health Sci Eng 2008; 5(3): 211-5.
22. Iranian Environmental Protection Agency (IEPA). Environmental regulations and standards of Iran. Tehran, Iran: Iran Global Environmental Law; 2008. p. 234-39. [In Persian].