Abstract:
The characterization of industrial effluents revealed that the nature and the volume of the pollution load were dependent on the type of industry. The value of BOD5 showed that the industries which use organic raw materials, for example,the beer breweries, the vegetable oil industries, and the textile mills, showed the highest pollution loads. The bottling companies which use "concentrates" as their raw materials generally showed intermediate values whereas the paint industries using inorganic raw materials showed the lowest BOD5 values. Estimation of the heavy metals revealed that Cd, Co, Ni,and Cr were below detection levels; Cu and Zn were within the WHO limits; Mn and Fe exceeded WHO maximum but fell below the maximum permissible level; while Pb was excessive (0.03mg/dm3) being above the highest desirable level. While Pb and Mn showed showed higher levels in the dry season than in the rainy season.The order of bio-accumulation of the metal ions in the predominant fish species: Synodontis membranaceus (catfish) and Oreochromis zilli (tilapia) in the study area was found to be Mn>Pb>Zn>Cu>Fe, indicating that both species of fish can be used to monitor Mn and Pb in water. Synodontis membranaceus was found to a better indicator for Mn while Oreochromis zilli was found to be better for Pb. The concentration levels for these metals are not such as to give cause for alarm since they are comparable to and sometimes, even lower than the levels in the mackerel fish samples(common in Nigerian diets). Presently, there is paucity of baseline data for many Nigerian rivers. It is hoped that the analytical data herein assembled would add to the growing Nigerian data bank
