Microbial Contaminant Effects of Pre-Treated Sewerage Wastewater on Receiving Surface Water in Ibadan, Nigeria

摘要

Microbial content of sewage wastewater and the impact on microbial population of receiving surface water was studied in university of Ibadan, Oyo State, Nigeria. Sewage wastewater samples were collected over 3 months period and examined for microbial content at the University of Ibadan surface water receiving pre-treated wastewaters from staff residential quarters, academic departments and students hostels. Surface water samples that were contaminated as a result of the sewage discharge were collected and analyzed for microbial content as compared to samples without sewage contamination 10 m upstream section from the point of discharge (control). Some physico-chemical parameters of the water samples were also examined. The sewage wastewater samples were highly contaminated; sewage wastewater showed mean faecal coliform count of 2.4x103 cfu/100 mL, mean total coliform count of 7.5x105 cfu/100 mL and mean total aerobic count of 6.7x107 cfu/100 mL. In the contaminated surface water sample, mean faecal coliform count (2.2x102 cfu/100 mL), total coliform count (3.1x105 cfu/100 mL) and total aerobic count (8.2x106 cfu/100 mL) are high compared to their respective values (1.1x102, 1.2x105 and 6.3x106 cfu/100 mL) for the control samples. These results were higher than Federal Environmental Protection Agency (FEPA) permissible limit of (500 cfu/100 mL). In this study, high microbial load in sewage wastewater with negative effects on microbial population in the receiving stream, further confirmed the need to pre-treat wastewater rather than discharging directly it to the environment.