Abstract:
Coagulation is a vital stage in treating contaminated water using coagulants that can be either synthetic or
natural. Currently, water is being treated by water treatment plants that use aluminum- or iron-based salts and
synthetic polymers for coagulation. However, these synthetic coagulants have flaws, including the production of
large amounts of chemical sludge, considerable effects on the pH of the purified water, relatively expensive to
use, and potentially toxic effects on the environment. The potential and constraints of replacing chemical co
agulants with natural plant extracts for water treatment are reviewed in this paper. Various natural coagulants
previously investigated for the removal of heavy metals, turbidity, pathogens, and other contaminants from
surface and synthetic water were analyzed based on dosage rates, active ingredients responsible for coagulation,
and extraction methods among other criteria. A comparative analysis was performed in studies in which both
conventional chemical coagulants and natural plant extracts were used for water treatment. Various studies have
shown that it is possible to replace chemical coagulants with plant-based extracts. It has been demonstrated that
it is possible to replace chemical coagulants with natural plant-based extracts because seed extracts such as those
of fenugreek can achieve turbidity removal efficiencies as high as 98% as compared to 85% for alum. The use of
natural coagulants may be beneficial for water treatment plants because they may produce less sludge than
chemical coagulants; this increases environmental sustainability while decreasing the cost of handling sludge.
They are less toxic than chemical coagulants and do not pose any adverse threats to the environment; therefore,
they are a safer alternative. However, studies are needed on how these plant-based coagulants can be
commercialized in the same way that chemical coagulants are readily available.
