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Abstract
This study aimed to thoroughly explore, optimize, and characterize a Bioflocculant produced by a novel Pseudomonas fluorescens PF-1 strain isolated from active sewage sludge. When examined under refined culture conditions, including an incubation temperature of 36°C, a neutral pH of 7, and the use of sucrose and yeast extract as the most effective carbon and nitrogen sources, respectively, this strain exhibited promising flocculating capabilities. An inoculum volume of 5% (v/v) further amplified Bioflocculant manufacturing. Under these conditions, the strain demonstrated remarkably high flocculating activity, reaching 87.4%. Biochemical composition analysis revealed that the extracted Bioflocculant principally comprised carbohydrates at 76.3% and proteins at 17.2%, indicating a polysaccharide-protein complex nature. FTIR spectroscopy supported the existence of functional groups, including carboxyl, hydroxyl, and amide, crucial for flocculation mechanisms. SEM imaging depicted a dense, interwoven fibril matrix perfectly suited for trapping and aggregating suspended particles. The Bioflocculant also manifested high thermal resilience up to 80°C and retained activity across a wide pH range from 4 to 8. Wastewater treatment tests employing genuine effluents showed outstanding pollutant removal proficiencies, with reductions in chemical oxygen demand (COD) and biological oxygen demand (BOD) achieving an impressive 90.2% and 88.6% respectively. These conclusions demonstrate strong potential as a Bioflocculant created by P. fluorescens PF-1 as an eco-friendly and highly effective replacement for conventional chemical flocculants in wastewater treatment applications.
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Copyright (c) 2025 Worood Younis Azawi, Imad Ahmed Rashid, Ezz El-Din Thabet Mahdi (Author)

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References
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References
Xia, S., Zhang, Z., Wang, X., Yang, A., Chen, L., Zhao, J., ... & Jaffrezic-Renault, N. (2008). Production and characterization of a bioflocculant by Proteus mirabilis TJ-1. Bioresource technology, 99(14), 6520-6527. https://doi.org/10.1016/j.biortech.2007.11.031
Campbell, A. (2002). The potential role of aluminium in Alzheimer’s disease. Nephrology Dialysis Transplantation, 17(Suppl 2), 17–20. https://doi.org/10.1093/ndt/17.suppl_2.17
Salehizadeh, H., & Shojaosadati, S. A. (2001). Extracellular biopolymeric flocculants: Recent trends and biotechnological importance. Biotechnology Advances, 19(5), 371–385. https://doi.org/10.1016/S0734-9750(01)00071-4
Sheng, G.P., Yu, H.Q., & Li, X.Y. (2010). Extracellular polymeric substances (EPS) of microbial aggregates in biological wastewater treatment systems: a review. Biotechnology Advances, 28(6), 882–894. https://doi.org/10.1016/j.biotechadv.2010.08.001
Li, Z., Zhong, S., Lei, H., Chen, R., Yu, Q., & Li, H. (2015). Production of a novel bioflocculant by Enterobacter cloacae and its application in removal of heavy metals from wastewater. Bioresource Technology, 196, 437–444. https://doi.org/10.1016/j.biortech.2015.07.101
Ghosh, S., Patra, P., & Dutta, S. (2014). Biodegradation of phenol by Pseudomonas fluorescens: effect of carbon and nitrogen supplementation. International Biodeterioration & Biodegradation, 94, 145–152. https://doi.org/10.1016/j.ibiod.2014.07.002
He, N., Li, Y., & Chen, J. (2010). Production of a novel polygalacturonic acid bioflocculant REA-11 by Citrobacter sp. and its application in dye wastewater treatment. Bioresource Technology, 101(4), 1044–1051. https://doi.org/10.1016/j.biortech.2009.08.095
Zhang, Z. Q., & Bo, L. (2007). Production and application of a novel bioflocculant by multiple-microorganism consortia using brewery wastewater as carbon source. Journal of Environmental Sciences, 19(6), 667-673. https://doi.org/10.1016/S1001-0742(07)60112-0
Gong, W. X., Wang, S. G., Sun, X. F., Liu, X. W., Yue, Q. Y., & Gao, B. Y. (2008). Bioflocculant production by culture of Serratia ficaria and its application in wastewater treatment. Bioresource Technology, 99(11), 4668–4674. https://doi.org/10.1016/j.biortech.2007.09.053
Zheng, Y., Ye, Z. L., Fang, X. L., Li, Y. H., & Cai, W. M. (2008). Production and characteristics of a bioflocculant produced by Bacillus sp. F19. Bioresource Technology, 99(16), 7686-7691. https://doi.org/10.1016/j.biortech.2008.01.068
Salehizadeh, H., & Yan, N. (2014). Recent advances in extracellular biopolymer flocculants. Biotechnology Advances, 32(8), 1506–1522. https://doi.org/10.1016/j.biotechadv.2014.10.004
More, T. T., Yadav, J. S. S., Yan, S., Tyagi, R. D., & Surampalli, R. Y. (2012). Extracellular polymeric substances of bacteria and their potential environmental applications. Journal of Environmental Management, 104, 1–12. https://doi.org/10.1016/j.jenvman.2012.03.021
Cosa, S., Mabinya, L. V., Olaniran, A. O., Okoh, O. O., Bernard, K., Deyzel, S., & Okoh, A. I. (2011). Bioflocculant production by Virgibacillus sp. Rob isolated from the bottom sediment of Algoa Bay in the Eastern Cape, South Africa. Molecules, 16(3), 2431-2442. https://doi.org/10.3390/molecules16032431
Wang, S. G., Gong, W. X., Liu, X. W., Tian, L., Yue, Q. Y., & Gao, B. Y. (2007). Production of a novel bioflocculant by culture of Klebsiella mobilis using dairy wastewater. Biochemical engineering journal, 36(2), 81-86. https://doi.org/10.1016/j.bej.2007.02.003
