ABSTRACT
In Nigeria, the practice of discharging industrial wastewater that is not in compliance with required standards as stipulated by the National Environmental Standards and Regulation Enforcement Agency (NESREA) has been a reoccurring problem. This unsafe practice has led to a continuous decline in freshwater quality with severe health and environmental implications. The need for continuous monitoring of industrial wastewater being discharged from industries has been emphasized. This study aimed to assess the quality of wastewater from selected industries in Benin City, Edo State, Nigeria. Wastewater samples were collected from Agricultural, Bakery, Carbonated soft drink and Textile industries. Physicochemical parameters such as pH, Electrical Conductivity (EC), Total Dissolved Solids (TDS), Total Hardness (TH), Chemical Oxygen Demand (COD), Hydrogen Bicarbonate, Nitrate, Sulphate, Chloride, Iron, Lead, Zinc, Copper, Cadmium, Chromium, Ammonium Nitrogen and Coliforms were analysed in the samples. The data from this study were analysed using statistical methods, including descriptive and inferential statistics (correlation analysis) in Microsoft Excel (2016). The study showed that the wastewater quality from the selected industries is very poor, and contained excessively high levels of Chloride (151.2mg/l-12101mg/l), COD (10.3mg/l5125mg/l) and heavy metals indicating gross contamination and pollution. The pH levels (6.4 and 5.8) of the effluents from the Agricultural and Bakery industries were lower than the minimum acceptable limit of 6.5 indicating acidic wastewater while Textile industry effluent with a pH mean value of 9.5 was higher than the maximum acceptable limit of 8.5 indicating alkaline wastewater, only the Carbonated soft drink industry falls within the NESREA acceptable limit. Correlation analysis carried out for the wastewater parameters from the Agricultural, Bakery and Textile industries indicated extremely strong positive correlation (0.99) between TDS and EC suggesting a high contamination load. There is therefore need for these considered industries to have a more effective wastewater management strategy. Regular monitoring and enforcement of regulatory standards to mitigate the environmental and health impacts of industrial wastewater pollution in Benin City is also strongly advised.
