This study presents a comparative and integrative evaluation of alum and Aloe vera as chemical and bio-based coagulants for turbidity removal from synthetic water. All experiments were conducted using bentonite based synthetic turbid water to ensure controlled assessment of coagulation behavior and to avoid overgeneralization to natural waters. Jar test experiments were performed by independently varying coagulant dose, solution pH, initial turbidity, slow mixing time, and settling duration. Alum exhibited consistently high turbidity removal across a broad pH range, while Aloe vera performed optimally under acidic conditions, achieving a maximum removal efficiency of 98.85%. A hybrid coagulant system combining alum and Aloe vera enhanced turbidity removal at higher initial turbidities (≥ 250 NTU), reaching up to 97.60% at a total dosage of 3 gm/L (each 1.5 gm/L of alum and Aloe vera ), suggesting complementary coagulation behavior. Zeta potential measurements indicated distinct mechanisms for alum and Aloe vera , consistent with charge neutralization and polymer-assisted flocculation, respectively. Although Aloe vera contributed slightly higher dissolved organic matter, its biodegradable nature highlights its potential as a partial coagulant substitute. Artificial neural network (ANN) models were applied as phenomenological predictors of turbidity removal, achieving high accuracy for alum (R² = 0.96) and moderate predictive performance for Aloe vera . Overall, the findings demonstrate the technical feasibility of integrating bio-based and hybrid coagulation strategies under controlled conditions, while highlighting the need for further mechanistic and sustainability assessments. • Aloe vera is a promising sustainable coagulant, achieving up to 98% turbidity removal at acidic pH. • ANN models effectively predicted turbidity removal, with alum-based models achieving R² = 0.96. • Zeta potential analyses revealed differing coagulation mechanisms, informing optimal coagulant selection.
Ghimire et al. (Sun,) studied this question.