Abstract

This study examines toxic metal concentration and bacteriological characteristics of effluents in some parts of southwestern Nigeria. Fourteen wastewaters were analyzed for their trace metal content using Inductive coupled plasma optical emission spectrometry (ICP-OES) while 72-samples were examined for the presence of bacterial load using Standard Microbiological methods (THC-Total viable count and TCC-Total coliform count). Isolates identities were confirmed with relevant biochemical tests. Elevated concentrations of Cu-0.299µg/l, Pb-0.10µg/l, Zn-4.62µg/l, Cr-0.20µg/l, As-0.3µg/l, Ni-0.192µg/l, Cd-0.02µg/l, Se-0.02µg/l, Co-0.099µg/l, V-1.71µg/l, U-0.50µg/l, Sr-1.81µg/l and Ba-0.82µg/l were observed in the cassava market/industry wastewater: signifying this as the most contaminated water in the area. Fe-24.8mg/l in the school wastewater may be geogenically sourced; indicating high degree of weathering with the presence of ferromagnesian minerals while Cu and As in cassava waste-water might be compositional based through bioavailability uptake/sources. Bacteriological analysis revealed Enterobacter spp. and Escherichia coli across all sampled sites; these were consistently present in the wastewaters and are primarily considered as indicators of faecal pollution capable of affecting human health via contamination of surrounding drinking water sources. These species have been associated with several clinical conditions such as pus formation, pneumonia, rheumatic fever and infections in immune compromised inhabitants while others cause severe illness such as respiratory and urinary tract infections in humans. Concentration of toxic metals in the cassava market/industry wastewater should be controlled or monitored and the wastewater made less toxic by constant treatment with adequate remediation facilities to remove the toxic constituents before discharging them to surface water bodies.

Key Words: Effluents, Metal burdens, Microbiological activities, Faecal pollution, Infections