Design Optimisation of a Water Treatment Plant for a University Campus in Sokoto State Using Response Surface Methodology

University campuses in Sokoto State, North West Nigeria, typically rely on groundwater abstraction systems that deliver water with elevated turbidity, total dissolved solids, and hardness requiring treatment before potable distribution. This study applies response surface methodology to optimise the design variables of a conventional coagulation-flocculation-sedimentation-filtration treatment train for a proposed 500 m3/day capacity water treatment plant for a university campus in Sokoto. Borehole water from the campus was characterised for turbidity, pH, total hardness, total dissolved solids, alkalinity, iron, manganese, and faecal coliforms. Jar test experiments were designed using a central composite design to evaluate the interactive effects of coagulant dose, flocculation speed, flocculation duration, and settling time on turbidity removal. A quadratic response surface model was fitted to turbidity removal data using ANOVA, and optimum operating conditions were identified by numerical optimisation. The model demonstrated excellent fit with an R2 of 0.947. Optimal conditions of 100 mg/L alum dose, 60 rpm flocculation speed, 20-minute flocculation time, and 30-minute settling time predicted 94.8% turbidity removal, validated experimentally at 93.6%. Process design calculations, equipment sizing, and capital cost estimation for the optimised treatment plant were completed, confirming technical feasibility within the campus capital budget allocation. The study provides a design template applicable to similar groundwater treatment projects at educational institutions across North West Nigeria. Keywords: response surface methodology, water treatment, coagulation, university campus, Sokoto State