Evaluating the Impacts of Sewage Disposal on Groundwater Composition in the Peri-Urban Community: A Case of Ikoto- Ijebu, Ogun State, Nigeria

Abstract

Groundwater is an essential resource that requires sufficient protection from human-induced pollution sources, assessments of water quality is an essential tool for water resources management strategies. the Physicochemical parameters measured were Hydrogen ion concentration (pH), Temperatures (oC), and electrical conductivity (EC), total bacteria and faecal coliform counts (Tb/fcc) were determined using the membranefiltration method; pH values was measure using a pH meter (Hach), the pH meter sensitivity was determined using buffers with a pH of 4.0 and pH of 9.0 and electrical conductivity values were taken, the TDS, total dissolved solids, measured using a meter; the SO42-, Fe2+ and NO3- were determined using Hach DR/2000 spectrophotometer. The water sampled temperatures range between 25.80 °C and 27.90 °C and arithmetic mean of 25.85 °C. The pH values of sampled wells and boreholes were in the acceptable pH range of 6.5 – 8.5, electrical conductivity values measured from the samples ranged from 94 μS per cm to 1418 μS per cm, having an arithmetic average of 370 μS/ cm; it is just one well that exceeded the permissible limit of 1000 μS per cm. The Total Dissolved Solids values ranged from 73 mg per Litre to 528 mg per Litre, an arithmetic average of 370 mg per Litre. The maximum value of 528 mg per Litre from zone B exceeded the acceptable limit of 500 mg per Litre. The concentrations are from 5 to 27×10 cfu / mL for total coliform counts and 0 to 12×10 cfu / mL for E. coli.77.2% of the samples fall within BOD values >3 mg per Litre, and 32.8% had BOD > 5 mg per Litre, signifying biogenic pollution and a possible seepage of mildly treated wastewater from sewage tanks near the wells. BOD and the bacteriological studies, for assessing biogenic pollution in water, indicated water samples are contaminated with wastewater.