Plant-based coagulants for sustainable treatment: Insights from a systematic review and their potential application...

Beyond their well-known role in air purification, plants can also act as natural coagulants for water, wastewater, and effluent treatment. This systematic review examined research on plant-based coagulants published between 2000 and 2024 across four databases (Web of Science, Scopus, ScienceDirect, and Taylor & Francis). Of the 895 retrieved articles, 175 met the eligibility criteria and were analyzed by plant species, preparation method, treatment matrix, application scale, and efficiency. Plant-based coagulants showed broad applicability in effluents, followed by water and wastewater, with high removal efficiencies for turbidity (up to 100%), microbiological parameters (80-98%), heavy metals (78-90%), and emerging contaminants (70-88%). Most studies investigated individual coagulants using simple preparation methods such as drying and grinding, though some species (e.g., Moringa oleifera, Aloe vera) enable even more accessible processing. Research remains largely at the bench-scale, with limited pilot applications, underscoring the need for scale-up and real-world validation. Reported benefits include low toxicity, reduced sludge production, and opportunities for using agricultural residues or invasive species. Despite Brazil's vast biodiversity and technical capacity as a BRICS country, few studies have explored its potential, highlighting the need for targeted research to foster sustainable water treatment solutions. Exploring the viability of plant-based coagulants represents not only a scientific challenge but also a strategic opportunity to advance sustainable, low-cost, and locally driven treatment solutions, particularly for biodiversity-rich countries like Brazil.