Physicochemical Analysis and PAHs Determination of Waste Water Discharged from Romi River, Kaduna State, Nigeria

This study evaluated the physicochemical properties and polycyclic aromatic hydrocarbon (PAH) contamination of Romi River, which receives effluent from the Kaduna Petroleum Refinery Company (KPRC). Water samples collected from selected upstream, discharge, and downstream locations were analyzed using standard physicochemical procedures and Gas Chromatography–Mass Spectrometry (GC–MS). The findings revealed acidic water conditions (pH 5.63 ± 0.26), high turbidity (455.00 ± 20.82 NTU), and elevated biochemical and chemical oxygen demand (BOD₅: 19.50 ± 9.85 mg/L; COD: 71.75 ± 37.04 mg/L), suggesting considerable organic pollution. The dissolved oxygen concentration (4.68 ± 1.23 mg/L) also indicated potential oxygen depletion, while detectable oil and grease (1.20 ± 0.50 mg/L) suggested petroleum-related contamination. GC–MS analysis identified six out of thirteen targeted PAHs, with a total concentration of 368.945 µg/L. Naphthalene was the predominant compound (360.443 µg/L), exceeding the stated World Health Organization drinking-water guideline, while the remaining detected PAHs occurred at considerably lower concentrations. The dominance of low-molecular-weight PAHs suggests petroleum-related contamination. Overall, the findings indicate that Romi River is affected by physicochemical deterioration and hydrocarbon pollution despite the prolonged inactivity of the refinery. The study therefore emphasizes the need for regular water quality monitoring, effective effluent management, and improved wastewater treatment to mitigate potential ecological and public health risks.