Abstract
Water pollution and scarcity are escalating global challenges that necessitate the development of sustainable water treatment technologies. Coagulation-flocculation, a crucial method for water purification, has traditionally relied on chemical coagulants such as alum and ferric chloride. However, these chemical treatments are associated with significant drawbacks, including the generation of toxic sludge, disruption of water pH, high operational costs, and adverse environmental impacts. In response to these issues, natural coagulants derived from plants, animals, and microorganisms have emerged as promising eco-friendly alternatives. This review explores the mechanisms, applications, and environmental advantages of natural coagulants in water treatment. Studies demonstrate their effectiveness in removing turbidity, heavy metals, pathogens, and other pollutants from both surface and synthetic wastewater. Compared to chemical coagulants, natural alternatives produce less sludge, are less toxic, and offer a more sustainable and environmentally friendly solution to water treatment. However, challenges persist, particularly in terms of scalability, standardization, and cost-effectiveness. The performance of natural coagulants can vary depending on geographical origin, and the lack of standardized extraction methods hinders their large-scale application. Future research should focus on optimizing extraction processes, addressing scalability issues, and exploring hybrid systems that combine the benefits of both natural and chemical coagulants. The continued development of natural coagulants holds great promise for creating more sustainable, cost-effective, and environmentally friendly water treatment solutions. Graphical Abstract