Assessing the coagulation efficiency and anti-microbial properties of fruit waste derived biomaterials for the treatment of surface water in Addis Ababa, Ethiopia

Access to safe drinking water remains a critical challenge in developing countries, largely due to contamination and the limited availability of chemical coagulants, which are often costly. In this study, we investigated the coagulation and antibacterial potential of readily available indigenous fruit wastes, mango seeds, papaya seeds, and orange peels compared to aluminum sulfate (alum). Fruit-based water treatment materials were aseptically prepared and evaluated in jar tests across dosages of 0–300 mg/L for turbidity removal, with water quality assessed before and after treatment. Antibacterial activity was tested against Escherichia coli and Staphylococcus aureus using the agar well diffusion method. All fruit-based coagulants exhibited dose-dependent turbidity reduction, achieving 3.4–4.3 NTU, which falls within the WHO permissible limit of <5 NTU and is comparable to alum (4 NTU), with minimal impact on pH. One-way analysis of variance (ANOVA) results also showed no significant differences among treatments at any dosage (p > 0.05). The antibacterial assays revealed inhibition zones of 14 mm (papaya), 12 mm (orange peel), and 11 mm (mango), indicating significant antimicrobial activity. These results demonstrate that fruit wastes can serve as low-cost, environmentally sustainable alternatives for water purification, aligning with circular economy principles and supporting progress toward the Sustainable Development Goals.