Plant-based coagulants for wastewater treatment: Recent advances and applications

The increasing global demand for clean water and sustainable wastewater management has intensified interest in eco-friendly treatment technologies. Among these, plant-based coagulants have emerged as promising alternatives to conventional chemical coagulants due to their biodegradability, low toxicity, cost-effectiveness, and reduced sludge generation. This review presents a comprehensive overview of recent advances in developing, characterizing, and applying plant-based coagulants for wastewater treatment. It discusses the fundamental coagulation mechanisms, such as charge neutralization, polymer bridging, sweep flocculation, and double-layer compression. Furthermore, it highlights the bioactive compounds and functional groups responsible for coagulation activity in various plant species. Applications in treating textile, agricultural, tannery, oil mill, and emerging pollutant-containing wastewater are critically evaluated. Additionally, recent innovations, including hybrid systems, extraction and purification enhancements, and molecular modifications, are explored to improve the performance and stability of plant-based coagulants. Future perspectives emphasise standardization, genetic engineering, and commercial scalability to facilitate broader adoption. This review underscores the potential of plant-based coagulants as viable, sustainable solutions for modern wastewater treatment challenges.