Optimization of rice husk ash, Moringa oleifera powder, biochar, and okra seed powder for turbidity and color removal in the Turag and Buriganga Rivers using response surface methodology

• Optimized natural coagulants for polluted river water treatment. • Response Surface Methodology improved coagulant performance predictions. • RHA and MOP showed the highest color and turbidity removal efficiency. • Dosage and treatment duration significantly influenced water quality. • Eco-friendly alternative to conventional chemical coagulants. Water pollution from untreated industrial and municipal effluents poses a growing concern in developing countries, particularly in major rivers such as the Turag and Buriganga in Bangladesh. This study evaluates the use of natural coagulants, including Rice Husk Ash (RHA), Moringa oleifera powder (MOP), Biochar (BC), and Okra Seed Powder (OSP), to remove turbidity and color from polluted waters. Using Response Surface Methodology (RSM), optimal coagulant dosages and post-filtration durations were identified. The study also…