Efficacy of Citrullus Lanatus (Water Melon Seed) Extract as Natural Bio-Coagulant for Physiochemical Characterization in Water Treatment System

Abstract

There has been a growing concern for environmental and health associated conventional chemical coagulants such as alum and the search for sustainable plant-based alternatives for water treatment process have intensified. Consequently, the objective of this paper investigated the efficacy of WMS extract as a natural bio-coagulant for physicochemical characterization in water treatment system. WMS powder was characterized using FTIR spectroscopy (Agilent Cary 630, ATR mode) and XRF spectrometry (CrossRoads Scientific XRS-FP) to identify functional groups and elemental composition relevant to the coagulation mechanism. Coagulation performance was assessed using the standard jar test method at different dosages of 10, 20, 30, and 40 mg/L respectively applied to synthetic turbid water (115 NTU, kaolin based), with alum as the reference coagulant. FTIR analysis confirmed a multi-functional composition comprising proteins (Amide I: 1621-1636 cm⁻¹; Amide II: 1509-1543 cm⁻¹), polysaccharides (C-O-C: 1040-1065 cm⁻¹), lipids (C-H: 2850-2930 cm⁻¹), phosphate groups (965-995 cm⁻¹), and hydroxyl/amine groups (3200-3500 cm⁻¹). XRF analysis identified major element constituents as SO3 (25.783 wt %), K2O (17.615 wt%), SiO2 (17.542 wt%), P2O5 (9.814 wt%), Al2O3 (8.960 wt%), CaO (7.934 wt%), and Fe2O3 (4.720 wt%), indicating synergistic organic and inorganic coagulation contributions. WMS achieved a maximum turbidity removal efficiency of 97.5% at 30 mg/L (3 NTU), compared to alum's 98.4% at 20 mg/L, meeting the WHO guideline of 5 NTU in both case. Lower volume sludge amenable to agricultural reuse. These findings establish WMS as a sustainable alternative to alum.