Abstract: The discharge of untreated wastewater constitutes a growing environmental and public health burden in developing regions where conventional treatment infrastructure is limited. This study evaluated the coagulation–flocculation performance of three agricultural waste-derived bio-coagulants: cassava peel (Manihot esculenta); banana peel (Musa paradisiaca); and Acacia seeds, in treating domestic and industrial wastewater from Oyo State, Nigeria. Wastewater from a university hostel and a garri processing industry was subjected to a standard jar test at two dosages (40 g/800 mL and 80 g/800 mL) over contact periods of 48 and 72 hours. Physicochemical parameters (BOD₅, TDS, TSS, EC, turbidity, pH, temperature), heavy metal concentrations (Pb, Cu, Zn), and microbiological indicators (total bacterial count, total coliform, faecal coliform) were measured alongside an untreated control. All three bio-coagulants significantly improved wastewater quality, with greater efficacy at higher dosage and longer contact time. Acacia seeds achieved the highest overall efficiency, recording turbidity reductions of up to 90.3% and BOD₅ reductions of up to 43.5% in industrial wastewater. Banana peel demonstrated the strongest BOD₅ removal from domestic wastewater (55.3% at 80 g, 72 h) and the greatest microbial load reduction. Cassava peel showed moderate but consistent performance across all parameters. TDS and electrical conductivity increases in several treatments are attributed to leaching of soluble organics from coagulant biomass; practical mitigation strategies are discussed. The strong acidity of both wastewater sources is contextualised relative to the garri processing environment. These findings support locally available agricultural wastes as cost-effective, biodegradable alternatives to chemical coagulants in low-income communities across sub-Saharan Africa.

Keywords: Acacia seeds, banana peel, bio-coagulant, cassava peel, coagulation–flocculation, heavy metals, jar test, natural coagulant, turbidity, wastewater treatment

Pages: 167-181

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