Assessment of on-site wastewater treatment in Urban Coastal Area of Lagos Island, Lagos State, Nigeria

Abstract

On-site wastewater management is a system being used to manage most of the domestic wastewater in all sectors of a nation’s economy where central wastewater treatment is not available. It is assumed that this system proffers treatment solution to the domestic wastewater in the households that do not have the central wastewater treatment plant. Hence, there is need to assess the On-site Wastewater Treatment (OSWT) in urban coastal areas of Lagos Island, Lagos State, in order to know the quality of the effluents being discharged into porous media with high water table. The following parameters, Acidity or alkalinity (pH), Temperature, Dissolved Oxygen (DO), Total Suspended Solid (TSS), Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Total Nitrogen (TN), Ammonium Nitrogen (NH4-N), NitrateNitrogen (NO3N), Ammonia Nitrogen (NH3-N),Phosphate (PO4-P) and Total Coliforms, were tested for. Results revealed that the average values recorded for TSS, BOD, COD, TN, NH4-N, NO3-N and PO4-P are 68.85, 142, 345.9, 56.6, 49.21, 0.19, 14.14 mg/L respectively, while the Total Coliform has 2.13E+08 col/100 mL. The values recorded for BOD, COD and Total Coliform are above the recommended values allowed by World Health Organisation (WHO) for the effluent discharge into the environment, this will be a threat to groundwater in the area.