Effectiveness of natural coagulants from non-plant-based sources for water and wastewater treatment-a review

The natural polymers used in water and wastewater treatment systems include starches, galactomannans, cellulose derivatives, chitosan, microbial polysaccharides, gelatin, glues, and alginate. These natural coagulants are capable of treating water from high to low turbid water and having removal efficiency of sometimes more than 98% that can be used for drinking purposes. Naturally occurring coagulants are usually presumed safe for human health, while there is a fear that using aluminum salts may induce Alzheimer's disease. These natural coagulants are usually used as coagulant aid in combination with some synthetic coagulants, their effectiveness as the primary coagulant is still in beginnings. The mechanisms of treatment in these coagulants include intermolecular bridging, complexation process, adsorption, and charge neutralization. A review of non-plant-based natural coagulants, coagulating mechanisms, effectiveness, and its applications has been presented.