This chapter comprehensively explores the structural, textural, and morphological characteristics of tannin-based natural coagulants, emphasizing their effectiveness in water and wastewater treatment applications. Tannins, belonging to a diverse class of polyphenolic compounds derived from various plant sources, have emerged as sustainable, eco-friendly, and cost-effective alternatives to synthetic coagulants. Their multifaceted nature and adaptability have made them a focal point in the quest for greener water management solutions. The chapter delves deeply into the mechanisms by which tannins facilitate coagulation and flocculation processes, elucidating their interaction with suspended particles and contaminants. Particular attention is given to their ability to neutralize charges and bridge particles, leading to the aggregation of flocs. Detailed analyses of the structural properties of tannins, including molecular weight, functional groups, and surface charge, highlight the pivotal roles these attributes play in determining coagulation efficiency. Textural characteristics, such as pore size distribution, porosity, and surface area, are also examined, shedding light on their influence on adsorption phenomena and particle bridging capabilities. Furthermore, the morphological aspects of tannin-based coagulants, such as their surface texture and floc formation behavior, are discussed to understand their contribution to the aggregation, growth, and sedimentation of flocs. By integrating these structural, textural, and morphological insights, the chapter provides a holistic understanding of the principles underpinning the performance of tannin-based coagulants. This comprehensive approach underscores their potential for sustainable water and wastewater treatment practices, contributing to eco-conscious water management strategies worldwide.
