Industrial Effluent Characterization and Biochemical Toxicity Assessment for Environmental Compliance in Ogun State

Industrial effluent discharge into water bodies in Ogun State's industrial zones poses significant biochemical toxicity risks to aquatic organisms and downstream human populations, yet systematic biochemical characterization for environmental regulatory compliance is inconsistently applied. This study performs industrial effluent characterization and biochemical toxicity assessment at six manufacturing facilities in the Sagamu and Ota industrial axes of Ogun State. Effluent samples were collected over four weeks at inlet, treatment, and outlet points of each facility's wastewater management system. Physicochemical parameters including pH, biochemical oxygen demand, chemical oxygen demand, dissolved oxygen, total dissolved solids, and total suspended solids were measured by APHA standard methods. Heavy metal concentrations in effluents were determined by atomic absorption spectrophotometry. Acute toxicity testing was performed using brine shrimp (Artemia salina) lethality assay, and sub-lethal biochemical toxicity in Clarias gariepinus (catfish) was assessed after ninety-six-hour laboratory exposure, measuring liver enzyme activities, oxidative stress parameters, and plasma cortisol as a stress biomarker. Results show that effluents from four of the six facilities exceeded FMENV discharge standards for at least two parameters. Heavy metal concentrations, particularly chromium and lead, exceeded acceptable limits in two textile-related facilities. Brine shrimp LC50 values were below 100 micrograms per millilitre for three effluents, indicating significant acute toxicity. Catfish exposed to diluted effluents showed significantly elevated liver enzymes, MDA, and plasma cortisol. The study provides the evidence base for improved regulatory enforcement of effluent standards. Keywords: industrial effluent, biochemical toxicity, environmental compliance, Ogun State, heavy metals.