Coconut Husk as a Natural Coagulant for Removing Colloidal Particles from Raw Water in River of Mendana Strait

The escalating global water quality crisis necessitates sustainable and efficient treatment solutions, particularly for challenging raw water sources. This study investigates the potential of coconut husk, an abundant agricultural byproduct, as a natural coagulant for treating raw water from the Mendana Strait River in Johor, Malaysia. A systematic jar test approach was employed to comprehensively optimize key coagulation parameters, revealing an optimal coagulant dosage of 1.2 g, a contact time of 40 minutes, an agitation speed of 80 rpm, and a remarkably high optimal pH of 11.13. This unique alkaline preference, distinct from conventional coagulants like alum (optimal pH 6–8), suggests novel underlying mechanisms, potentially involving surface modification and the release of active components from the lignocellulosic husk. The optimized process achieved an exceptional turbidity removal efficiency of up to 95.16%, demonstrating coconut husk’s strong potential in clarifying highly turbid water. Furthermore, detailed characterization using Fourier Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM), and Elemental Microanalysis (CHNS) provided crucial insights into the material’s physicochemical changes and its active role in contaminant removal, including nitrogenous compounds. Beyond its technical performance, coconut husk offers significant environmental and economic advantages by minimizing chemical usage, valorizing agro-waste, and reducing treatment costs, making it a highly promising and sustainable solution for water purification, particularly in resource-constrained and rural settings.