Dosage-based application versus ratio-based approach for metal- and plant-based coagulants in wastewater treatment: Merits, limitations, and applicability

The crisis on water resource and environmental pollution are forcing to upgrade conventional technology of wastewater treatment for water recycle and reuse. Coagulation-flocculation is the common wastewater treatment that has shown efficient removal performance based on various coagulants from metal-to plant-based compounds. Dosage application is the widely used method to apply coagulant in coagulation-flocculation treatment. This study introduces a new ratio-based approach using theoretical calculation for coagulant dosing in wastewater treatment. A comparative study of total suspended solid removal performance by dosage-based application versus ratio-based approach is performed by evaluating the R-2 value. A demonstration on the dosage-based application versus ratio-based approach efficiencies is presented through a simulation of sludge production. Comparative analysis and simulation indicate that ratio-based approach has higher R-2 value and lower sludge production with low coagulant usage compared with dosage-based application for the same influent characteristic. Merits, limitations, applicability, and future approaches for ratio-based approach are detailed for upcoming research directions and technological development.