The impact of industrial wastewater on the physicochemical and microbiological characteristics of groundwater in Ajao- Estate Lagos, Nigeria.

In Ajao Estate, it is believed that poor quality of its groundwater is unconnected to the dislodging of wastewater into the environment by food- and wine-producing industries operating in the area. To ascertain this claim, the impact of this wastewater on microbiological and physicochemical quality of the groundwater was evaluated. Microbiological result of water samples revealed decrease in Staphylococcus aureus, Clostridium spp., Escherichia coli, etc. count from the industrial wastewater dislodging point. Groundwater samples collected from areas under the influence of industrial wastewater showed higher concentration of physicochemical elements than those outside the area of influence (control) except pH (5.96) and Cl (19.80 ppm), while in soil samples, reverse was the case. In groundwater samples, most of the physicochemical parameters were not within the permissible limit for drinking water except zinc (Zn) (0.214 to 1.660 ppm) which falls within World Health and Nigerian limit of 3.0 ppm. The degree of contamination/pollution of all the heavy metals in the soil samples were neither polluted nor contaminated, even though the contamination factor (CF) and geoaccumulation index (I-geo) of cadmium (Cd) was the highest in main soil samples and in control. Negative correlations exist between all the heavy metals in soil samples and those in groundwater except copper (Cu). Reasonable concentrations of all these heavy metals with the exception of manganese (Mn) were seen in the sample of industrial wastewater, suggesting that industrial wastewater may be one of the possible sources of their concentration in groundwater even though there might be other sources.