Characterization and Performance of Pineapple Stem Cationic Starch as an Eco-Friendly Flocculant for Phosphate Removal from Wastewater

Municipal wastewater contains high levels of phosphate, which contributes to eutrophication in aquatic ecosystems. While coagulation-flocculation is a widely used method for phosphate removal, conventional coagulants often present challenges related to environmental sensitivity and performance under varying pH. This study investigates the use of a starch-based cationic coagulant derived from pineapple stem waste for phosphate removal in simulated municipal wastewater. The starch was chemically modified through etherification with glycidyltrimethylammonium chloride (GTAC), introducing quaternary ammonium groups to improve coagulation efficiency. Structural modifications were confirmed using Fourier Transform Infrared Spectroscopy (FTIR), which showed successful substitution of hydroxyl groups with ammonium functionalities. Coagulation-flocculation experiments were conducted to evaluate the effects of pH and coagulant dosage on phosphate removal. The modified starch achieved the highest phosphate removal efficiency at a dosage of 1.0 g/L and pH 5, significantly outperforming unmodified starch. The results demonstrate that chemical modification enhanced the starch’s performance as a coagulant under acidic conditions. This study highlights the potential of utilizing modified starch from agricultural waste as an effective and sustainable alternative for phosphate removal, offering a promising approach for improving wastewater treatment technologies.