After 100 years, Quo vadis** coagulation-flocculation?

Water treatment through coagulation-flocculation with chemicals like metal salts or biopolymer materials has been applied for small-scale applications throughout human history. Industrialization and the need to provide potable water for communities has led to widespread use of coagulation-flocculation (CF), mostly with metal salts. With the introduction of synthetic polymers, questions about their health effects have risen, necessitating research into natural alternatives versus established synthetic materials. This shift is projected to be as significant as the introduction of synthetic coagulant/flocculant aides nearly a century ago. While the advent of such aids has led to improvements and important technical innovations, the CF process has remained largely unchanged. More recent developments include ballasted flocculation and research on sustainable alternatives (lignocellulose biomass, coated fibers, mineral particles etc.), which present a major opportunity to shift the CF process toward sustainability and circularity. Sustainable alternatives like biopolymer solids could supplant dissolved coagulants and flocculants, while drastically improving both the efficacy and economy of the water treatment process with potentially reusable CF-materials that adopt a “coagulation-like” process to achieve sustainability and circularity in water treatment processes.