Optimization of Ferrofluid Based Microplastics Removal: A Case Study of Kibangu River, Tanzania

Document Type : Original Research Paper

Authors

1 Hubei Key Laboratory of Construction and Management in Hydropower Engineering, China Three Gorges University, Yichang, China

2 College of Hydraulic and Environmental Engineering, China Three Gorges University, Yichang, China

3 Ardhi University, Dar Es Salaam, Tanzania

4 College of Electrical Engineering and New Energy, China Three Gorges University, Yichang, China

10.22059/poll.2025.389227.2767

Abstract

Microplastics (MPs) pollution has become a major global environmental concern, significantly affecting aquatic ecosystems. This study assessed MP contamination in the Kibangu River and developed a novel ferrofluid-based method for MP removal. MP abundance in the river ranges from 9 to 21 particles/l, with an average of 15 particles/l. The highest abundance was recorded at the Riverside Interchange (21 particles/l), while Nida Textiles exhibited the lowest (9 particles/l). Optimization experiments identified 3.2 g/l ferrofluid concentration and a 25-minute contact time as the most effective conditions for removal, beyond which no significant improvement was observed. Removal efficiency varied with MP size and polymer type; smaller particles (38 µm) exhibited higher removal rates due to their larger surface area to volume ratio. Polyethylene (PE) achieved a 93% removal rate, while polypropylene (PP) reached 88%. Fresh vegetable and castor oils significantly enhanced ferrofluid performance at lower concentrations (1–1.5 ml), with fresh vegetable oil showing the highest efficiency. However, higher oil concentrations and used oils were less effective. These findings underscore the importance of optimizing oil selection and operational parameters to enhance MP removal. This study presents a scalable, environmentally friendly solution to mitigate MP pollution, providing a foundation for further research and potential applications in water treatment and environmental management.

Keywords

Main Subjects


Abdellatif, G., Mahmoud, A., Peters, R., & Mostafa, M. (2021). Waste Plastics and Microplastics in Africa: Negative Impacts and Opportunities. 
Abidli, S., Toumi, H., Lahbib, Y., & El Menif, N. (2017). The first evaluation of micro- plastics in sediments from the complex lagoon-channel of Bizerte (Northern Tunisia). Water Air Soil Pollut, 228 (7), 262.  doi: 10.1007/s11270-017-3439-9.
Akarsu, C., Kumbur, H., & Kideys, A.E. (2021). Removal of microplastics from wastewater through electrocoagulation-electroflotation and membrane filtration processes. Water science and technology: a journal of the International Association on Water Pollution Research, 84(7), 1648–1662. doi: 10.2166/wst.2021.356. 
Alalwan, H.A., Mohammed Ali, N., Mohammed, M.M., Mohammed, M.F., & Alminshid, A.H. (2023). A comparison study of methyl green removal by peroxi-coagulation and peroxi-electrocoagulation processes. Cleaner Engineering and Technology, 13, 100623. doi: 10.1016/j.clet.2023.100623. 
Al-Amshawee, S.K., Mohd, Y.M., Alalwan, H.A., Lee, W.H., & Dai, F. (2022). Experimental investigation of biofilm carriers of varying shapes, sizes, and materials for wastewater treatment in fixed bed biofilm reactor: a qualitative study of biocarrier performance. Journal of Chemical Technology & Biotechnology, 97 (9), 2592-2606. doi: 10.1002/jctb.7131.
Alimi, O., Fadare, O., & Okoffo, E. (2021). Microplastics in African ecosystems: current knowledge, abundance, associated contaminants, techniques, and research needs, Science of the Total Environment, Vol. 755, 142422. doi: 10.1016/j.scitotenv.2020.142422 
Allan, T., & Nelson, R. (2022). The past, present, and future of plastic pollution, Marine Pollution Bulletin Volume, 176,113429, ISSN 0025-326X. doi: 10.1016/j.marpolbul.2022.113429.
Aragaw, T. (2020). Surgical face masks as potential source for microplastic pollution in the COVID 19 scenario. Marine Pollution Bulletin, 159,111517. doi: 10.1016/j.marpolbul.2020.111517
Babayemi, J., Nnorom, I., Osibanjo, O., & Weber, R. (2019). Ensuring sustainability in plastics use in Africa: consumption, waste generation, and projections. Environ Sci Eur, 31, 60. doi: 10.1186/s12302-019-0254-5.
Babel S., & Dork H. (2021). Identification of micro-plastic contamination in drinking water treatment plants in Phnom Penh, Cambodia. Journal of Engineering and Technological Sciences, 53 (3), 210307. doi: 10.5614/j.eng.technol.sci.2021.53.3.7. 
Bellasi, A., Binda, G., Pozzi, A., Galafassi, S., Volta, P., & Bettinetti, R. (2020). Microplastic Contamination in Freshwater Environments: A Review, Focusing on Interactions with Sediments and Benthic Organisms. Environments, 7(4):30. doi: 10.3390/environments7040030.
Bucci, K., & Rochman, C. (2020). Micro-plastic pollution is everywhere, but scientists are still learning how it harms wildlife.  Accessed 29 November 2024. 
Campanale, C., Massarelli, C., Savino, I., Locaputo, V., & Uricchio, V.F. (2020). A Detailed Review Study on Potential Effects of Microplastics and Additives of Concern on Human Health. International journal of environmental research and public health, 17(4), 1212. doi: 10.3390/ijerph17041212.  
Chen, C., Deng, J., & Zhang, Q. (2023). Microplastic pollution and characteristics in the surface waters of the middle and lower reaches of the Han River along Hubei Province, China. Int. J. Environ. Sci. Technol, 20, 10205–10216. doi: 10.1007/s13762-022-04559-0. 
Chiani, M., Rasta, M., Taleshi, M., & Elmi, F. (2025). The role of organisms’ size in microplastic pollution monitoring: Insights from Mytilaster lineatus and Amphibalanus improvisus. Marine Environmental Research, 204, 106863. doi: 10.1016/j.marenvres.2024.106863. 
Choong, W., Hadibarata, T., & Tang, D. (2020). Abundance and Distribution of Microplastics in the Water and Riverbank Sediment in Malaysia – A Review. Biointerface Research in Applied Chemistry: n. pag. Doi: 10.33263/briac114.1170011712
Choong, W., Hadibarata, T., Yuniarto, A., Tang, K., Abdullah, F., Syafrudin, M., Al Farraj, D., & Al-Mohaimeed, A. (2021). Characterization of microplastics in the water and sediment of Baram River estuary, Borneo Island. Marine pollution bulletin, 172, 112880. doi: 10.1016/j.marpolbul.2021.112880. 
De-la-Torre, G., & Aragaw, T. (2021). What we need to know about PPE associated with the COVID-19 pandemic in the marine environment. Marine pollution bulletin, 163, 111879. doi: 10.1016/j.marpolbul.2020.111879. 
Dey, T. K., Uddin, M. E., & Jamal, M. (2021). Detection and removal of microplastics in wastewater: evolution and impact. Environmental science and pollution research international, 28(14), 16925–16947. doi: 10.1007/s11356-021-12943-5. 
Ding, L., Mao, F., Guo, X., Yang, X., Zhang, Q., & Yang, C. (2019). Microplastics in surface waters and sediments of the Wei River, in the northwest of China. The Science of the total environment, 667, 427–434. doi: 10.1016/j.scitotenv.2019.02.332. 
Ding, N., An, D., Yin, X., & Sun, Y. (2020). Detection and evaluation of microbeads and other microplastics in wastewater treatment plant samples. Environ Sci Pollut Res, 27, 15878–15887. doi: 10.1007/s11356-020-08127-2.  
East African Community. (2022). Draft East African Standard: Portable water – Specification (Fourth Edition 2022). 
Enfrin, M., Dumée, L.F., & Lee, J. (2019). Nano/microplastics in water and wastewater treatment processes - Origin, impact and potential solutions. Water research, 161, 621–638. doi: 10.1016/j.watres.2019.06.049. 
Grbic, J., Nguyen, B., Guo, E., Bem, Y.J., Sinton, D., & Rochman, C.M. (2019). Magnetic Extraction of Microplastics from Environmental Samples. Environ. Sci. Technol. Lett. doi: 10.1021/acs.estlett.8b00671. 
Habl, A. M., Amooey, A. A., Mohammed M. M., & Alalwan, H. M. (2024). Electro Oxidation Process for Wastewater Treatment in Petroleum Refineries. Pollution, 10 (2), 819-832. doi: 10.22059/poll.2024.371677.2236. 
Hamzah, S., Ying, L., Azmi, A., Razali, N., Hairom, N., Mohamad, N., & Che Harun, M. (2021). Synthesis, Characterisation and Evaluation on the Performance of Ferrofluid for Microplastic Removal from Synthetic and Actual Wastewater. Journal of Environmental Chemical Engineering, doi: 10.1016/j.jece.2021.105894. 
Henriques, K. (2022). Analysis of the microplastic removal efficiency of synthesized ferrofluids and the development of an automated prototype for aquatic environments. The Columbia Junior Science Journal: 1-5. 
International Union for Conservation of Nature I. (2021). Marine Plastic Pollution. Accessed 20 October 2024.
Kankanige D., & Babel S. (2021). Contamination by ≥6.5 μm-sized microplastics and their removability in a conventional water treatment plant (WTP) in Thailand. Journal of Water Process Engineering 40, 101765. doi: 10.1016/j.jwpe.2020.101765. 
Kankanige, D., & Babel, S. (2020). Smaller-sized micro-plastics (MPs) contamination in single-use PET-bottled water in Thailand. The Science of the total environment, 717, 137232. doi: 10.1016/j.scitotenv.2021.147656. 
Katrivesis, F. K., Sygouni, V., Paraskeva, C. A., & Papadakis, V. G. (2021). A Performance Comparison of Pilot-Scale Sand Filtration and Membrane Filtration of Glafkos River Water. Journal of Marine Science and Engineering, 9(2), 203. doi: 10.3390/jmse9020203. 
Khalik, W., Ibrahim, Y., Tuan, S., Govindasamy, S., & Baharuddin, N. (2018). Microplastics analysis in Malaysian marine waters: A field study of Kuala Nerus and Kuantan. Marine pollution bulletin, 135, 451–457. doi: 10.1016/j.marpolbul.2018.07.052. 
Khan, F.R., Shashoua, Y., Crawford, A., Drury, A., Sheppard, K., Stewart, K., & Sculthorp, T. (2020). The Plastic Nile’: First Evidence of Microplastic Contamination in Fish from the Nile River (Cairo, Egypt). Toxics, 8(2), 22. Doi: 10.3390/toxics8020022. 
Khan, M. T.; Ahmad, M.; Hossain, M. F.; Nawab, A.; Ahmad, I.; Ahmad, K., & Panyametheekul, S. (2023). Microplastic removal by coagulation: a review of optimizing the reaction conditions and mechanisms. Water Emerg. Contam. Nanoplastics 2023, 2, 22. doi: 10.20517/wecn.2023.39.
Kundu, M.N., Komakech, H.C., & Lugomela, G. (2022). Analysis of Macro- and Microplastics in Riverine, Riverbanks, and Irrigated Farms in Arusha, Tanzania. Archives of environmental contamination and toxicology, 82(1), 142–157. doi: 10.1007/s00244-021-00897-1.
Kuok, H., & Tang, D. (2021). Abundance and Distribution of Microplastics in the Water and Riverbank Sediment in Malaysia - A Review. Biointerface Research in Applied Chemistry, 11. 11700-11712. Doi: 10.33263/BRIAC114.1170011712. 
Kyara, V.C., Rahman, M.M., & Khanam, R. (2021). Tourism expansion and economic growth in Tanzania: A causality analysis. Heliyon, 7(5), e06966. Doi: 10.1016/j.heliyon.2021.e06966.
Lehel, J., & Murphy, S. (2021). Microplastics in the Food Chain: Food Safety and Environmental Aspects. Reviews of environmental contamination and toxicology, 259, 1–49. doi: 10.1007/398_2021_77.
Li, D., Liu, K., Li, C., Peng, G., & Zhu, W. (2020). Profiling the vertical transport of microplastics in the West Pacific Ocean and East Indian Ocean with a novel in situ filtration tech- nique. Environ. Sci. Technol, 54 (20), 12979–12988. doi: 10.1021/acs.est.0c02374 
Li, J., Huang, W., Xu, Y., Jin, A., Zhang, D., & Zhang, C. (2020). Microplastics in sediment cores as indicators of temporal trends in microplastic pollution in Andong salt marsh, Hangzhou Bay, China. Regional Studies in Marine Science, 35: 101149. doi: 10.1016/j.rsma.2020.101149 
Li, L., Cheng, L., & Kai, I. (2021). Study of Ferrofluid and Magnetic Fields. Proceedings of the International Conference on Industrial Engineering and Operations Management.  doi: 10.46254/AN11.20211159.  
Ma, M., Liu, S., Su, M., Wang, C., Ying, Z., Huo, M., Lin, Y., & Yang, W. (2022). Spatial distribution and potential sources of microplastics in the Songhua River flowing through urban centers in Northeast China. Environmental Pollution, 292: 118384. doi: 10.1016/j.envpol.2021.118384.  
Malale, M. P., & Munishi, S. (2018). Surface Water Quality In peri-Urban Areas in Dar Es Salaam, Tanzania: The Case of Ng’ombe River. Tanzania Journal of Engineering and Technology, 37(1). doi: 10.52339/tjet.v37i1.481. 
Mao, Y., Li, H., Gu, W., Yang, G., Liu, Y., & He, Q. (2020). Distribution and characteristics of microplastics in the Yulin River, China: Role of environmental and spatial factors. Environmental pollution (Barking, Essex: 1987), 265(Pt A), 115033. doi: 10.1016/j.envpol.2020.115033. 
Martinez, L., & Kim, B. (2020). Removal of microplastics in water using oil-based ferrofluid solution. New Jersey City University. 
Mayoma, B.S., Sørensen, C., Shashoua, Y., & Khan, F.R. (2020). Microplastics in beach sediments and cockles (Anadara antiquata) along the Tanzanian coastline. Bulletin of environmental contamination and toxicology, 105(4), 513–521. doi: 10.1007/s00128-020-02991-x.
Nabeel, M., Kutty, R., & Hemalatha, J. (2014). Novel Coconut Oil Based Magnetite Nanofluid as an Ecofriendly Oil Spill Remover. Industrial & Engineering Chemistry Research, 53(40), 15725–15730. doi: 10.1021/ie502150g.
Nayebi, R., & Shemirani, F. (2021). Ferrofluids-based microextraction systems to process organic and inorganic targets: The state-of-the-art advances and applications. TrAC Trends in Analytical Chemistry, 138. 116232. doi: 10.1016/j.trac.2021.116232. 
Nchimbi, A.A., Kosore, C.M., Oduor, N., Shilla, D.J., Shashoua, Y., Khan, F.R., & Shilla, D.A. (2022). Microplastics in Marine Nearshore Surface Waters of Dar es Salaam and Zanzibar, East Africa. Bulletin of environmental contamination and toxicology, 109(6), 1037–1042. doi: 10.1007/s00128-022-03620-5.
Nejat, N., Sattari, M., Mohsenpour, R., Shi, X., & Rasta, M. (2024). Microplastics abundance, distribution and composition in surface waters, sediments and fish species from Amir˗ Kalayeh Wetland, Northern Iran. Environmental Science and Pollution Research, 31(14), 22024-22037. doi: 10.1007/s11356-024-32627-0. 
Nizam, N., Mohanasunthar, S., Azmi, A., Tuan, A., Ibrahim, S., & Wan, M. (2023). Removal Efficiency for Micro-Polystyrene in Water by the Oil-Based Ferrofluid Employ Response Surface Methodology. Sains Malaysiana.  Doi: 10.17576/jsm-2023-5208-03.
Oehlsen, O., Cervantes-Ramírez, I., Cervantes-Avilés, P., & Medina-Velo, A. (2022). Approaches on Ferrofluid Synthesis and Applications: Current Status and Future Perspectives. ACS omega, 7(4), 3134–3150. doi: 10.1021/acsomega.1c05631. 
Othman, A., Hasan, H., Muhamad, M., Ismail, N., & Abdullah, S. (2021). Microbial degradation of microplastics by enzymatic processes: a review. Environ Chem Lett, 19, 3057–3073. Doi: 10.1007/s10311-021-01197-9. 
Park, J.W., Lee, S.J., Hwang, D.Y., & Seo, S. (2020). Recent Purification Technologies and Human Health Risk Assessment of Microplastics. Materials (Basel, Switzerland), 13(22), 5196. doi: 10.3390/ma13225196.
Rasta, M., Khodadoust, A., Taleshi, S., Lashkaryan, S., & Shi, X. (2024). Potential use of gammarus (Pontogammarus maeoticus) and shrimp (Palaemon elegans) as biomonitors of microplastics pollution in coastal environments. Environmental Pollution, 362, 124959. doi: 10.1016/j.envpol.2024.124959. 
Sharma, S., Sharma, V., & Chatterjee, S. (2021). Microplastics in the Mediterranean Sea: Sources, Pollution Intensity, Sea Health, and Regulatory Policies. Frontiers in Marine Science, 8, 634934. Doi: 10.3389/fmars.2021.634934. 
Sturm, M., Horn, H., & Schuhen, K. (2021). The potential of fluorescent dyes-comparative study of Nile red and three derivatives for the detection of microplastics. Analytical and bioanalytical chemistry, 413(4), 1059–1071. doi: 10.1007/s00216-020-03066-w.
Talvitie J., Mikola A., Koistinen A. & Setälä O. (2017). Solutions to microplastic pollution – removal of microplastics from wastewater effluent with advanced wastewater treatment technologies. Water Research 123, 401–407. doi:10.1016/j.watres.2017.07.005. 
Uwaegbulam, C., Nwannekanma, B., & Gbonegun, V. (2018). Producer’s Responsibility and Plastic Pollution Crisis. The Guardian. 
Wallyn, J., Anton, N., & Vandamme, T.F. (2019). Synthesis, Principles, and Properties of Magnetite Nanoparticles for In Vivo Imaging Applications-A Review. Pharmaceutics, 11(11), 601. doi: 10.3390/pharmaceutics11110601. 
Wang, C., Wang, H., & Liu, Y. (2014). Separation of polyethylene terephthalate from municipal waste plastics by froth flotation for recycling industry. Waste management (New York, N.Y.), 35, 42–47. doi: 10.1016/j.wasman.2014.09.025.
Wang, X., Bolan, N.S., Tsang, D.C., Sarkar, B., Bradney, L., & Li, Y. (2020). A review of microplastics aggregation in aquatic environment: Influence factors, analytical methods, and environmental implications. Journal of hazardous materials, 402, 123496. doi: 10.1016/j.jhazmat.2020.123496. 
Wang, Z., Lin, T., & Chen, W. (2020). Occurrence and removal of microplastics in an advanced drinking water treatment plant (ADWTP). The Science of the total environment, 700, 134520. doi: 10.1016/j.scitotenv.2019.134520. 
Westphalen, H., & Abdelrasoul, A. (2018). Challenges and Treatment of Microplastics in Water. InTech. doi: 10.5772/intechopen.71494.
Yang, L., Li, K., Cui, S., Kang, Y., An, L., & Lei, K. (2019). Removal of microplastics in municipal sewage from China’s largest water reclamation plant. Water research, 155, 175–181. Doi: 10.1016/j.watres.2019.02.046.
Yang, Z., Lü, F., Zhang, H., Wang, W., Shao, L., Ye, J., & He, P. (2021). Is incineration the terminator of plastics and microplastics? Journal of Hazardous Materials, 401, 123429. doi: 10.1016/j.jhazmat.2020.123429.
Zhang, Y., Jiang, H., Bian, K., Wang, H., & Wang, C. (2021). A critical review of control and removal strategies for microplastics from aquatic environments. Journal of environmental chemical engineering, 9, 105463.  doi: 10.1016/j.jece.2021.105463. 
Zhao, H.; Zhou, Y., Han, Y., Sun, Y., Ren, X., Zhang, Z., & Wang, Q. (2022). Pollution status of microplastics in the freshwater environment of China: a mini review. Water Emerg. Contam. Nanoplastics, 1:5. doi: 10.20517/wecn.2021.05. 
Zhou, G., Wang, Q., Zhang, J., Li, Q., Wang, Y., Wang, M., & Huang, X. (2020). Distribution and characteristics of microplastics in urban waters of seven cities in the Tuojiang River basin, China. Environmental research, 189, 109893. doi: 10.1016/j.envres.2020.109893.