PHYSICOCHEMICAL ANALYSIS OF STORMWATER RUNOFF FROM A CEMENT MANUFACTURING PLANT IN NIGERIA

Abstract

This study evaluates the physicochemical characteristics of stormwater runoff from a cement manufacturing plant in Kogi State, Nigeria, during the rainy season (June to August 2024). The objective was to assess the environmental impact of cement production processes on stormwater quality. The parameters analyzed include pH, electrical conductivity (EC), total suspended solids (TSS), total dissolved solids (TDS), dissolved oxygen (DO), biochemical oxygen demand (BOD), chemical oxygen demand (COD), chloride and sulphate ions, and heavy metal concentrations. Results revealed pH values ranging from 6.52 to 11.50, with alkaline runoff exceeding regulatory limits during peak production activities. The TSS levels (288 ± 2.65 to 420 ± 5.57 mg/L) and TDS concentrations (200 ± 2.74 to 312 ± 3.21 mg/L) were within the permissible limits of the National Environmental Standards and Regulations Enforcement Agency (NESREA) of Nigeria. The BOD and COD values occasionally exceeded thresholds, indicating organic pollution during certain conditions. Sulphate levels were significantly elevated (up to 540 mg/L), suggesting atmospheric deposition of industrial emissions. Heavy metal analysis revealed variable concentrations of Fe, Zn, Cu, Pb, and Mn ions, with some samples exceeding NESREA limits for Fe and Cu. The findings underscore the need for effective stormwater management strategies in cement plants to mitigate environmental impacts and ecological risks associated with industrial stormwater discharges in Nigeria, and to ensure compliance with regulatory standards.